Fig. 1.3 Left: Wilhelm Conrad Röntgen (1845–1923), a portrait by Nicola Perscheid, circa 1915. Right: The first roentgenogram—the hand of Röntgen’s wife after its irradiation with X-rays (Dec 22, 1895)


Fig. 1.4 Philipp Eduard Anton von Lenard (1862–1947)


Fig. 1.5 Left: Henri Becquerel (1852–1908), circa 1905. Right: Becquerel’s photographic plate exposed to a uranium salt


Fig. 1.6 Left: Ernest Rutherford (1871–1937). Right: Rutherford in his laboratory at McGill University (Canada), 1905. (Reproduced with permission)


Fig. 1.7 Marie and Pierre Curie in their Laboratory, circa 1904


Fig. 1.8 Marie Curie in a mobile military X-ray unit during the Great War (WWI), circa 1915


Fig. 1.9 Radiation injury. (Sources: left—Finzi [26], right) https://wellcomecollection.org/works/g94c5mtb


Fig. 1.10 A bottle of Radithor—one of the most famous varieties of radium-infused water commercially available in the USA in the 1920s


Fig. 1.11 Bergonié, Tribondeau, and Regaud


Fig. 1.12 Cartoon from “Life,” February 1896. The New Roentgen Photography. “Look pleasant, please”


Fig. 1.14 Mask to hold the radium needles for treatment of skin cancer [79]


Fig. 1.2 Crookes, or cathode ray, tube. (Source: Wikimedia. Reproduced with permission)


Fig. 2.1 Plot of the projectile kinetic energy vs. the de Broglie wavelength. The sizes of a nucleon, uranium nucleus, lead orbitals and water molecule are also reported. (Courtesy of Dr. Marc Verderi, Laboratoire Leprince-Ringuet, CNRS/IN2P3, Ecole Polytechnique, Institut Polytechnique de Paris, France)


Fig. 2.3 The Compton process. The incident photon (γ-ray) interacts with an electron initially at rest resulting in a scattered photon (at angle θ) and electron (at angle Φ). The energy (E) and momentum (p) of the photon and electron before and after (marked with ′) scattering are given in the figure (Created with BioRender)


Fig. 2.4 A typical example of a sequence of energy deposits. The energy of an original 1.25 MeV photon is deposited in five subsequent Compton processes with a final energy deposition in the form of a photoelectric process. The figure shows the mean range in water (dotted arrows) for the incoming photon and the reduced-energy photons emitted for each Compton process. The scale shown in the bottom left only applies to photons. The electron mean range is much shorter starting at about 2 mm going down to about 36 μm in the last Compton scattering (which is still larger than a typical cell diameter) (Created with BioRender)


Fig. 2.5 Visualization of the electronic interactions (left) and the nuclear interaction (right) of a particle with atomic number z, mass m, and energy E with matter with atomic number Z, mass number A, and density ρ (Created with BioRender)


Fig. 2.6 (a) Energy loss for protons (purple) and carbon (blue) ions depends on ion type and ion energy. For lower energies, the nuclear energy loss (dotted lines) starts to get an influence. At energies above ~0.0005 MeV/u for protons and ~0.005 MeV/u for carbon ions, the electronic energy loss is dominant (dashed lines) and the nuclear energy loss can be even neglected for higher energies. E/A is the energy divided by mass number. (b) Energy loss for a proton with initial energy of Ein = 200 MeV with a range in water of 256 mm on the left and for a carbon ion with initial energy of Ein = 375 MeV/u with a range in water of 251 mm on the right: at the end of range at a path length, the energy loss is increasing and rapidly goes to zero when the ion stops. The curve shape for the carbon ion is the same as for the proton but with a higher energy loss at all times. Energy losses are calculated via SRIM (SRIM—The Stopping and Range of Ions in Matter, J. Ziegler, http://www.srim.org/). (c) Stopping power of electrons depending on electron energy simulated using estar (https://physics.nist.gov/PhysRefData/Star/Text/ESTAR.html). (d) Energy loss of electrons in adipose tissue with penetration depth (inspired by Hazra et al. 2019) (licensed under CC-BY-4.0) [26]


Fig. 2.7 Quark structure of proton and neutron, with binding gluons shown (Created with BioRender)


Fig. 2.8 Natural sources of ionizing radiation and their pathways (Figure from European Commission, Joint Research Centre—Cinelli, G., De Cort, M. & Tollefsen, T., European Atlas of Natural Radiation, Publication Office of the European Union [41]) (licensed under CC-BY-4.0)


Fig. 2.10 Mechanism and critical targets for ionizing radiation to produce biological damage through direct and indirect effects (Created with BioRender)


Fig. 2.11 Uranium, 238U/radium, 226R (4n + 2) decay series. Radioactive decay series. (2020, September 8). [Retrieved August 16, 2021, from https://chem.libretexts.org/@go/page/86256 (open-source CC-BY textbook)]


Fig. 2.12 Hypothetical decay series involving four nuclides A, B, C, and D, with various different decay constants λA, λB, etc. (a) Radioactive equilibrium. (b) Transient equilibrium


Fig. 2.13 (a) Schematic representation of the complete Karlsruhe radionuclide chart. (b) Detailed representation of different radionuclide boxes. (c) Different colors of boxes representing the different decay modes, from left to right: stable isotope, proton emission (p), alpha decay (α), electron capture or beta-plus decay (ε or β+), isomeric transition (IT), beta-minus decay (β−), spontaneous fission (SF), cluster decay (CE), and neutron decay (n). [(Figure adapted from Soti et al., 2019) (licensed under CC-BY-4.0)]


Fig. 2.14 General principle of the radioimmunoassay (Created with BioRender)


Fig. 2.15 Schematic representation of the mechanism of action of radionuclide therapy. The blue line represents the path of ionizing radiation (Created with BioRender)


Fig. 2.16 Schematic representation of the energy deposition of the ionizing radiation and tissue range of the different emission types used for targeted radionuclide therapy, being β−, α, and Auger electron emitters (Created with BioRender)


Fig. 2.17 Comparison of the SPECT (a) and PET (b) imaging techniques used for clinical diagnostic (adapted with permission of Hicks and Hofman, 2012) [75]


Fig. 2.18 Metabolization of glucose and its radioactive analogue [18F]FDG (Created with BioRender)


Fig. 2.19 Dose and LET distribution for proton beams of various energy in water (simulated using TOPAS MC)


Fig. 2.20 RBE variation with LET. RBE increases as LET increases, up to a maximum LET value of about 100 keV/μm. An “overkilling” effect is observed for higher LET values (Created with BioRender)


Fig. 2.22 Effects of the dose rate on clonogenic cell survival for a human melanoma cell line irradiated at dose rates of 1.6, 7.6, and 150 cGy/min. At equal biological effectiveness, e.g., 0.01 cell survival (broken line), high-dose-rate irradiation has larger relative biological effect than low-dose irradiation, resulting in a dose reduction of approximately 5 Gy, i.e., a DRF of 1.6 (12.8/7.7). Dotted lines: (A) no repair; (B) condition of full repair at infinitely low dose rate. (Figure adapted from Steel [107], with permission)


Fig. 2.23 OER as a function of LET (Created with BioRender)


Fig. 2.24 Radiation syndrome phases (Created with BioRender)


Fig. 2.25 The dominant syndromes leading to death vary with dose and time postexposure. Therapy is possible for doses lower than approximately 8–10 Gy (depending on medical resources) (Created with BioRender)


Fig. 2.26 Smoking effects on solid cancer baseline rates. (a) Smoking ERR as a function of attained age for males (black curves) and females (gray curves). The solid curves represent lifelong smokers, while the dashed curves represent past smokers from the age at which they quit (shown are male past smokers quitting at age 50 years and female past smokers quitting at age 55 years). (b) Total smoking risk for current smokers, past smokers, and those who never smoked (thin solid curves) for males and females. The curves represent typical smoking histories. Male smokers started at age 20 years and smoked 20 cigarettes per day, while female smokers started at 30 years and smoked 10 cigarettes per day (reproduced with permission from Grant et al. © 2017 Radiation Research Society) [53]


Fig. 2.28 Low-dose hyper-radiosensitivity (HRS) can be observed in a typical survival curve. The dashed line represents the linear-quadratic (LQ) model, while the solid line shows the induced repair (IR) model


Fig. 2.29 Probable players driving the non-targeted effects of radiation


Fig. 2.31 Clastogenic factors (created with BioRender)


Fig. 2.32 Mechanisms involved in radiation-induced genomic instability (Created with BioRender)


Fig. 3.2 The four DNA bases with respective hydrogen bonds (dashed lines). G guanine, C cytosine, A adenine, T thymine


Fig. 3.3 Examples of DNA base damages. In base lesions, the chemical structure of any DNA base is modified (highlighted with yellow and red), whereas in abasic sites, the N-glycosidic bond between the DNA base and the 2-deoxyribose is broken (as shown with red arrow). G guanine, C cytosine, A adenine, T thymine, H-bond hydrogen bond, P phosphate


Fig. 3.4 Examples of DNA cross-links. Chemical bonds (yellow) are created between two DNA bases within the same DNA strand (intra cross-link) or opposite strands of double-stranded DNA (inter cross-link). Proteins (blue) can become cross-linked to DNA to form DNA-protein cross-link (DPC). G guanine, C cytosine, A adenine, T thymine, H-bond hydrogen bond, P phosphate


Fig. 3.5 Single-strand breaks (SSB): an illustration of a single-strand break in DNA. G guanine, C cytosine, A adenine, T thymine, H-bond hydrogen bond, P phosphate


Fig. 3.6 Double-strand breaks (DSB): an illustration depicting different types of double-strand breaks in DNA. G guanine, C cytosine, A adenine, T thymine, H-bond hydrogen bond, P phosphate


Fig. 3.7 Short and long patch base excision repair: recognition of the DNA lesion occurs by a specific DNA glycosylase which removes the damaged base by hydrolyzing the N-glycosidic bond. The remaining AP site is processed by APE. Depending on the cleavability of the resulting 5′dRP by Polβ, repair is performed via the short or long patch BER pathway. Reproduced with permission from [24]. AP-endonuclease apurinic/apyrimidinic endonuclease, AP-lyase apurinic/apyrimidinic lyase, OH hydroxide, P phosphate, 5’dRP 5′ deoxyribose phosphate, Lig III ligase III, XRCC1 X-ray repair cross-complementing 1, RF-C replication factor C, Fen1 flap structure-specific endonuclease 1, PCNA proliferating cell nuclear antigen, Lig I ligase I


Fig. 3.8 Nucleotide excision repair (NER) pathway: during global genomic repair (GGR), recognition of the DNA lesion occurs by XPC–HR23B, RPA–XPA, or DDB1–DDB2. DNA unwinding is performed by the transcription factor TFIIH and excision of the lesion by XPG and XPF–ERCC1. Finally, resynthesis occurs by Polδ or Polε and ligation by DNA ligase I. During transcription-coupled repair (TCR), the induction of the lesion results in blockage of RNAPII. This leads to assembly of CSA, CSB, and/or TFIIS at the site of the lesion, by which RNAPII is removed from the DNA or displaced from the lesion, making it accessible to the exonucleases XPF–Ercc1 and XPG cleaving the lesion-containing DNA strand. Resynthesis again occurs by Polδ or Polε and ligation by DNA ligase I. 23B: Reproduced with permission from Christmann et al. [24]. DDB1 DNA damage-binding protein 1, DDB2 DNA damage-binding protein 2, RPA replication protein A, TFIIH transcription factor IIH, ERCC1 excision repair cross-complementing group 1 protein, Polyδ/ε DNA polymerase delta/epsilon, PCNA proliferating cell nuclear antigen, Lig1 DNA ligase 1, RNAPII RNA polymerase II, CSA and CSB Cockayne syndrome factors A and B, TFIIS transcription initiation factor IIS, HR23B homologous recombinational repair group 23B


Fig. 3.9 Overview of eukaryotic mismatch repair system. In the human cell, the predominantly found MutSα (MSH2–MSH6) or the MutSβ recognizes the DNA mismatch repair and initiates its repair. Some of the crucial molecules which participate in the repair are the MutLα (MLH1-PMS2), the proliferating cell nuclear antigen (PCNA), and the replication factor (RCF). EXO1 catalyzes the repair, and ligase finally ligates the repaired DNA


Fig. 3.10 Overview of homologous recombination (HR) pathways in double-strand break repair. When cells suffer a DSB (purple lines), they can repair them either by HR, with the help of a template that is homologous (turquoise lines), or by the NHEJ pathway. (a) BRCA1 promotes the HR pathways, whereas the Shieldin complex, RIF1, and 53BP1 promote the NHEJ pathway. (b) The resection process is performed by the MRN complex along with CtIP, EXO1, BLM, and DNA2 that form the 3′ ssDNA overhangs. These overhangs are then coated with the RPA (green boxes), which is later shifted by the RAD51 (brown circles). On the other hand, single-strand annealing occurs in case of the RAD-independent repair process, where annealing of the complementary DNA sequences takes place followed by overhangs cleaved by the flap endonuclease and finally the ends of the DNA are ligated. (c) Positive regulators of RAD51 such as RAD51 paralogs, BRCA2, and PALB2 aid in the formation of the RAD51 filament, whereas RECQL5 and FBH2 negatively regulate RAD51. (d) The RAD51 paralogs and RAD54A-B support the RAD51-mediated homology searching and strand invasion. At the same time, FANCM and RTEL negatively govern the RAD51-mediated D loops. (e) The homologous template in the form of sister chromatid or a homologous chromosome is used by the DNA polymerases to copy the missing sequence. (f) The DNA is resolved into a noncrossover product when SDSA dislodges the D loop. (g) In case there is an extension of the heteroduplex and development of Holliday junction created by the second-end capture, the intermediate states can be resolved by either resolution or dissolution. (h) The outcome of resolution is both the crossover and noncrossover products. (i) The outcome of dissolution is a noncrossover product. Adapted with permission (CCBY) from Sullivan and Bernstein [35]. Abbreviations: DSB double-strand DNA break, HR homologous recombination, NHEJ Non-homologous end joining, BRCA1 breast cancer gene 1, RIF1 Rap1-interacting factor 1, 53BP1 p53-binding protein 1, MRN MRE11–RAD51–NBS1 complex, CtIP CtBP-interacting protein, EXO1 exonuclease 1, BLM Bloom’s syndrome helicase, RecQ helicase-like gene, DNA2 DNA replication helicase/nuclease 2, ssDNA single-stranded DNA, RPA replication protein A, RAD51 RAD51 recombinase, PALB2 partner and localizer of BRCA2, RECQL5 RecQ-like helicase 5, FBH2 also GNA11, G protein subunit alpha 11, FANCM FA complementation group M, RTEL regulator of telomere elongation helicase 1, SDSA synthesis-dependent strand annealing


Fig. 3.11 Schematic of the principal steps of NHEJ. (I) IR triggers the formation of DNA DSB in the cell nucleus. (II) To act on these, the NHEJ pathway commences with the movement of Ku (Ku70/Ku80) proteins towards the loose ends in the DNA DSB. (III) Ku70/Ku80 forms a complex embracing the ends protecting DNA integrity. DNA DSBs with noncomplex termini can be ligated directly after this step as end processing is not required. (IV) When the ends in the DSB require end trimming, the DNA-PKcs is recruited onto DNA via association to the Ku70/Ku80 complex forming a platform for subsequent steps. (V) Once associated to Ku proteins and DNA, DNA-PKcs undergoes autophosphorylation which changes its conformation. (VI) In this way, DNA-PKcs is active as a kinase and regulates the association of multiple DNA end-trimming proteins (e.g., Artemis, WRN, Polμ/λ, PNK), which restores the nucleotides at the termini allowing ligation to take place. (VII) The ligation step is controlled by the DNA ligase IV complexes, which apart from ligase IV also include XRCC4, XLF, and PAXX. At the end of the trimming and ligation step, some bases may be lost causing loss of genomic information which may cause mutations. Abbreviations: DNA DSB DNA double-strand break, NHEJ Non-homologous end joining, Ku dimeric Ku70/Ku80 protein complex, DNA-PKcs DNA-dependent protein kinase catalytic subunit, WRN protein deleted in Werner syndrome, Polμ/λ DNA polymerase μ/λ, PNK polynucleotide kinase, XRCC4 X-ray repair cross-complementing protein 4, XLF XRCC4-like factor, PAXX paralog of XRCC4 and XLF


Fig. 3.12 Structure of DNA organization. The DNA forms a double-helix structure, which is wrapped around histones forming so-called nucleosomes. The nucleosomes form complex fibers of 30 nm size, which themselves form the higher order chromatin fibers, which are in the range of 300 nm. In the interphase, these fibers build the chromatin territories, where territories from different chromosomes can overlap, forming so-called networks. In the metaphase, the higher order chromatin fibers are condensed to form chromosomes. (Adapted with permission (CCBY) from Liu et al. [40])


Fig. 3.13 Localization of DNA damage on chromatin: radiation damage induced by high-LET alpha particle radiation microscopically visualized by γH2AX as a biomarker for double-strand breaks (left, magenta), chromatin labeling (middle, green), and merge of the two (right)


Fig. 3.14 Morphologies of mitotic catastrophe (a) and senescence (b). (a) Fluorescence image of cancer cells undergoing mitosis. The DNA is labeled with DAPI and mitotic spindles using α-tubulin staining. The cells exhibiting mitotic catastrophe are treated with photodynamic therapy (PDT), Taxol (Tx), or nocodazole (Nc). The control shows normal mitotic spindles. The treated cells show various types of altered spindles and mitosis. Scale bar: 10 μm. Reproduced with permission (CCBY) from Mascaraque et al. [64]. (b) Phase-contrast images of Chang cells. Senescence was induced using 1 mM of deferoxamine. (Reproduced with permission (CCBY) from Kwon et al. [65])


Fig. 3.15 Mechanisms by which genotoxic agents cause micronuclei and other nuclear anomalies. Micronuclei (MN) can originate from lagging acentric chromosomes or chromatid fragments or whole chromosomes at anaphase in mitosis. Nuclear bud (NBUD) formation represents the process of extrusion of the amplified/surplus DNA, DNA repair-recombinational protein complexes, and possibly excess chromosomes from aneuploidic cells. Nucleoplasmic bridges (NPBs) originate from dicentric chromosomes. This arises because the centromeres of dicentric chromosomes are often pulled in opposite directions and defective separation of sister chromatids occurs during anaphase leading to bridge formation, which can be observed as an NPB in telophase


Fig. 3.16 Depending on the cell type, different micronucleus assays can be employed to assess and determine the genotoxicity and cytotoxicity of different chemical and physical factors. Applications of each assay are outlined in their respective boxes. The most popular CBMN assay can be applied to cultured human lymphocytes or cell lines to measure MN and other chromosomal instability biomarkers such as NPBs and NBUD. The mammalian erythrocyte micronucleus assay is performed on immature erythrocytes from bone marrow to determine cytogenetic damage after radiation exposure. The buccal micronucleus cytome assay is done in rapidly dividing buccal epithelial exfoliated cells (oral cavity) to analyze MN and other cytogenetic biomarkers (source of DNA damage, cytotoxicity, etc.). Occasionally, MN assay is performed on nasal mucosa cells or urine-derived cells for detection of chromosomal damage caused by environmental and lifestyle factors, occupational exposures, prognosis of cancer, and certain diseases. Although the objective and method of performance are similar to CBMN or bone marrow MN assays, these tests have not gained much popularity so far


Fig. 3.17 Types of chromosomal mutations. Nonlethal aberrations are observed at the first mitosis after irradiation. Duplication: one or more copies of a DNA segment/a region of a chromosome are formed. Inversion: A segment of a chromosome breaks off and reinserts in reverse orientation within the same chromosome. Deletion: A part of a chromosome/one or more nucleotides from a segment of DNA are missing or deleted. Translocation: It involves two chromosomes in which a piece of one chromosome breaks off and rejoins to another chromosome. Insertion: A segment of one chromosome is removed and inserted to another chromosome or the same chromosome


Fig. 3.18 Human metaphase cell irradiated with 5 Gy gamma rays. Two dicentric chromosomes, three acentric fragments, and a ring chromosome could be found. From https://www.qst.go.jp/site/nirs-english/1369.html (accessed 05/2022)


Fig. 3.19 Techniques to assess constitutional or acquired chromosomal abnormalities using standard banding techniques (left) or advanced molecular cytogenetic techniques (right). Standard cytogenetic techniques are traditionally performed by karyotyping of stained metaphase chromosomes or by flow cytometry. Chromosome banding is used to produce alternating light and dark regions, also referred to as “cytogenetic bands,” along a chromosome with the use of special stains (abbreviations are listed below). Chromosome banding patterns are essential in pairing and ordering all the chromosomes, known as karyotyping. Flow cytometry-based procedures have been developed to assess numerical (ploidy) and structural (telomere length) chromosomal aberrations in mitotic cells largely based on DNA content. To overcome the limitations of the banding analysis, advanced cytogenetic techniques are introduced. In techniques based on ISH, fluorescently labeled “painting” probes are used to localize nucleic acid sequences. FISH identifies chromosomal rearrangements and mapping-specific genes on individual mitotic chromosomes. GISH determines the origin of genomes or chromatins in hybrids. RISH reveals cellular patterns of mRNA expression in cells. CGH-based techniques provide an overview of chromosome ploidy level (gain and loss) throughout the whole genome. CGH with the use of microarrays—aCGH—detects aneuploidies, deletions, duplications, and amplifications based on DNA content. Southern blotting and PCR-based molecular cytogenetic techniques have good potential to detect chromosomal abnormalities from trace amounts of specific regions of DNA/RNA. G-banding Giemsa banding, Q-banding quinacrine fluorescence banding, R-banding reverse banding, C-banding centromere banding, ISH in situ hybridization, FISH fluorescence in situ hybridization, GISH genomic in situ hybridization, RISH RNA in situ hybridization, CGH comparative genomic hybridization, aCGH array comparative genomic hybridization, QF-PCR quantitative fluorescence polymerase chain reaction, qPCR quantitative polymerase chain reaction, MAPH multiplex amplifiable probe hybridization, MLPA multiplex ligation-dependent probe amplification


Fig. 3.20 The presence and action of MPF protein in the cell control premature chromosome condensation induction. Cyclin B oscillates through the cell cycle being undetectable during interphase, very low in G1, gradually increasing from S, reaching maximum in G2, and decreasing abruptly at G2/M transition. This corresponds to the MPF activity during cell cycle. MPF maturation/mitosis-promoting factor


Fig. 3.21 Premature chromosome condensations (PCCs) at various stages of the cell cycle: darkly stained metaphase chromosomes belong to mitotic CHO cells, whereas the lighter stained to the interphase CHO cells. (a) G0-PCCs, (b) G1-PCCs, (c) S-PCCs (reproduced with permission (CCBY) from Pantelias et al. [73]), (d) G2-PCCs. CHO Chinese hamster ovary


Fig. 3.22 Schematic illustration of chromothripsis. It is a phenomenon where one single catastrophic event leads to a massive and localized shattering of one or few chromosomes. Shattered chromosome fragments are not properly rejoined resulting in a new genome configuration and a large number of complicated chromosomal aberrations


Fig. 3.23 Radiation-induced DNA damage foci. 53BP1 (left, cyan) and γΗ2ΑΧ (middle, magenta) foci in HeLa cells irradiated with 1.2 Gy alpha particles and spatially fixed at 60 min postirradiation. Colocalization of γΗ2ΑΧ and 53BP1 foci is shown (right). Yellow line indicates the cell nucleus


Fig. 3.24 DNA repair kinetics. (a) Formation and disassembly of γH2AX foci in human cancer cells irradiated with 1 Gy or 2 Gy X-rays. (b) Representative microscopic images for γH2AX foci 1 h and 2 h after X-ray irradiation. (Reproduced with permission (CCBY) from Mariotti et al. [88])


Fig. 3.25 DNA repair protein markers forming small foci. 2BN hTert (XLF-deficient) human fibroblasts were analyzed 2 h post-IR with 1 Gy. Cells were stained against DAPI, pATM, and RAD51, or DAPI, γH2AX, and RAD51. RAD51 is present in a subset of pATM and γH2AX foci. Reproduced with permission (CCBY) from Geuting et al. [92]. DAPI 4′,6-diamidino-2-phenylindole used for staining nuclei, XLF XRCC4-like factor


Fig. 3.26 Possible ROS-mediated oxidative stress. Upon exposure to IR, oxidative stress can induce collateral damage, such as lipid peroxidation, protein denaturation, nuclear and DNA damage, mitochondrial damage, and apoptotic death by releasing cytochrome c. Oxidative stress owing to excess ROS generation induces overexpression of antioxidant enzymes in an attempt to control ROS levels. At high levels of oxidative stress, antioxidant defenses are overwhelmed, which leads to inflammatory and cytotoxic responses. (Reproduced with permission from Sanvicens and Marco [95]). NP nanoparticles, ROS reactive oxygen species


Fig. 3.27 Antioxidant defense mechanisms


Fig. 3.28 NRF2 protection against oxidative stress and excessive inflammatory responses involved in IR injury. NRF2 induces antioxidant response genes, like SOD, CAT, GPX, and GST that enhance ROS elimination. In addition, expression of enzymes such as GR and GS increases GSH cellular content and antioxidant capacity of the cell. Reduction in ROS levels decreases the expression of NFKβ, the main contributor to the inflammatory response. Moreover, NRF2 enhances the expression of HO-1 and its activity in the production of CO that reduces NFKβ activity, pro-inflammatory cytokine secretion (IL-6, TNFα, and IL-1β), and pro-inflammatory enzyme activity (COX-2 and iNOS). ARE antioxidant-responsive element, NRF2 NF-E2-related factor 2, SOD superoxide dismutase, CAT catalase, GPx glutathione peroxidase, GST glutathione S-transferase, GS glutathione synthetase, GR glutathione reductase, GSH glutathione, ROS reactive oxygen species, NFKβ nuclear factor kappa β, IL-6 and 10 interleukin 6 and 10, IL-1β interleukin 1 beta, TNFα tumor necrosis factor alpha, COX-2 cyclooxygenase 2, iNOS inducible nitric oxide synthase, HO-1 heme oxygenase 1


Fig. 3.30 Main oxidative products of DNA, lipids, and proteins. Oxidative products (listed in gray boxes) are formed depending on the free radicals (RNS/ROS) and the biomolecule target (amino acids, proteins, phospholipids, nucleic acids). These products can be used as oxidative stress biomarkers. RNS reactive nitrogen species, ROS reactive oxygen species


Fig. 3.31 Overview of cell cycle: functions of different phases, cyclins and CDKS, and CDIs


Fig. 3.32 Age-response of cells after radiation. Left: Age-response curves for HeLa-S3 cells (open circles: synchronized cells, triangles: asynchronous cells) irradiated with 3 Gy X-rays (= 300 rad) at different time points after selection in mitosis and the fraction of cells with incorporated [3H]-thymidine in DNA after a 20-min pulse (black circles, right y-axis). Right: Dose-response curves for HeLa-S3 cells synchronized by mitotic selection and X-irradiated at different times after selection. 0 h: mitosis, 5 h: early G1 phase, 14 h: S phase, 19 h: late S/G2 phase. [Reproduced with permission from Terasima and Tolmach [115]]


Fig. 3.33 Telomeres, their shortening, the senescence state, and immortal cells. An adult cell chromosome with telomeres and the enzyme telomerase, which plays a crucial role in telomere end lengthening (left). Telomere characteristics in an adult cell’s chromosome, after multiple replications, at cell senescence, and when the cell is immortal (left to right, blue box). (Adapted with permission from Aunan et al. [119])


Fig. 3.34 Overview of cellular senescence processes. ROS reactive oxygen species, ATM ataxia-telangiectasia mutated, ATR ATM and Rad3-related protein, Cdk2/4/6 cyclin-dependent kinase 2/4/6, RB retinoblastoma tumor suppressor gene, SASP senescence-associated secretory phenotype, SA-β-gal senescence-associated beta-galactosidase


Fig. 3.35 Overview of cell death and cell death-protective mechanisms in response to radiation. Radiation-induced cell death is influenced by different factors, such as radiation factors, cell intrinsic factors, and cellular microenvironment factors (left). Cell death pathways are listed to the right. The mechanisms and importance of these principal cell death forms are described in detail in the text


Fig. 3.37 The intrinsic and extrinsic route to apoptosis. Intrinsic stress signals (e.g., DNA damage, hypoxia, metabolic stress) or lethal stimuli (e.g., IR exposure) can induce intrinsic mitochondrial apoptosis (middle). Cleaved or truncated Bid (tBid) can also connect the extrinsic pathway to the intrinsic route. In the extrinsic pathway, ligands for death receptors (left) can trigger caspase activation, but the pathway can also be activated when some dependence receptors are inactivated (right). Abbreviations: FasL Fas ligand, TRAIL TNF-related apoptosis-inducing ligand, TNF tumor necrosis factor, Fas Fas cell surface death receptor, TRAILR TNF-related apoptosis-inducing ligand receptor, TNFR tumor necrosis factor receptor, TRADD TNFR1-associated death domain protein, FADD Fas-associated protein with death domain, caspase cysteine-aspartic proteases, BID BH3-interacting domain death agonist, tBID truncated BID, Bcl-2 B-cell lymphoma 2 (an apoptotic inhibitor), BCL2L1 Bcl-2-like 1, MOMP mitochondrial outer membrane permeabilization, BH3 Bcl-2 homology 3, DIABLO direct inhibitor of apoptosis-binding protein with low pI, APAF-1 apoptotic peptidase-activating factor 1, Bax Bcl2-associated X (an apoptotic regulator), Bak Bcl-2 homologous antagonist/killer, XIAP X-linked inhibitor of apoptosis protein, SMAC second mitochondria-derived activator of caspase, UNC5B Unc-5 netrin receptor B


Fig. 3.36 Cell death pathways operative in mitotic catastrophe. Different signaling events triggered in response to a nonfunctional mitosis are shown. Upon DNA damage, cells which lack functional p53 can go out from mitosis without commencing cytokines or initiate cell death even in mitosis. Apoptosis and necrosis signaling in the context of mitotic catastrophe are depicted


Fig. 3.38 TP53-mediated intrinsic route to apoptosis. The mechanisms of TP53-induced apoptosis through the Bcl-2-regulated pathways in cells undergoing stress are shown. DNA damage triggers stress signaling, which in turn causes stabilization of the TP53 protein in the nucleus. Subsequently, TP53 as a nuclear transcription factor increases the expression of BH3-only proteins such as PUMA and NOXA and downregulation of BCL-2 or BCL-XL expression. The BH3-only proteins bind and inhibit the anti-apoptotic or pro-survival BCL-2 family proteins, so as to unleash the cell death effectors (BAX/BAK) which are often held as hallmarks of apoptosis in affected cells. Oligomerization of BAX/BAK causes MOMP, with subsequent release of cytochrome c, formation of the apoptosome complex, and activation of CASP9 and subsequently effector caspases, which causes apoptotic features of the dying cells. Abbreviations: ROS reactive oxygen species, MOMP mitochondrial outer membrane permeabilization, BH3 Bcl-2 homology 3, PUMA p53 upregulated modulator of apoptosis, BAD Bcl-2-associated agonist of cell death, CHOP CCAAT/enhancer-binding protein homologous protein, Bcl-2 B-cell lymphoma 2 (an apoptotic inhibitor), Bcl-xL B-cell lymphoma-extra-large, Bax Bcl2-associated X (an apoptotic regulator), Bak Bcl2 antagonist killer 1, APAF-1 apoptotic peptidase-activating factor 1, caspase cascade of aspartate-specific cysteine proteases


Fig. 3.39 Overview of ceramide signaling and connection to the apoptotic machinery. IR-induced lipid oxidative damage causes sphingomyelinase activation at the plasma membrane, followed by hydrolysis of sphingomyelin and release of ceramide. High dose of IR-induced DNA DSBs can also trigger the mitochondrial ceramide synthase for de novo synthesis of ceramide. Inhibition of SERCA and calcium depletion in ER promote ER stress. Expression of downstream pro-apoptotic factor, e.g., CHOP, increases. The UPR activator proteins, ATF6, IRE1, and PERK, alter ER stress. The PERK pathway via ATF4-dependent NRF2 expression triggers the CHOP-mediated apoptotic pathway. CHOP can also be induced by spliced ATF-6 (in Golgi), which regulates the Bcl-2 protein family. CAPPs can alter the BCL-2 protein family, which determines the commitment of cells to apoptosis. Abbreviations: Cer ceramide, CerS1–6 a family of six ceramide synthases, SMase sphingomyelinase, SERCA sarco-endoplasmic reticulum calcium transport ATPase, ER endoplasmic reticulum, ATF6 activating transcription factor 6, IRE1 inositol-requiring enzyme 1, PERK protein kinase R-like ER kinase, NRF2 nuclear factor erythroid 2-related factor-2, ATF4 activating transcription factor 4, CHOP CCAAT/enhancer-binding protein homologous protein, Mt mitochondria, CAPPs ceramide-activated protein phosphatase, Bcl-2 B-cell lymphoma 2 (an apoptotic inhibitor), Bcl-xL B-cell lymphoma-extra-large, Bax Bcl-2-associated X (an apoptotic regulator), RNS reactive nitrogen species, ATP adenosine triphosphate


Fig. 3.40 Methods to detect cell death, in particular apoptotic cell death. The schematic diagram outlines various biological assays used to determine apoptotic cell death. Some of these assays can also be used to assess other types of cell death. These assays are based on the morphological criteria and distinguishing features of apoptotic pathways, e.g., staining for PS exposure on the outer plasma membrane (by annexin V assay) and caspase-3 activation or PARP cleavage (by, e.g., western blotting). Cell viability assays such as membrane integrity assays and reproductive assays are performed to monitor live cells in culture and measure an enzymatic activity as a marker of viable cells by using different classes of colorimetric reagents and substrates generating a fluorescent signal. Results from these assays do not always indicate apoptosis, but more about cell death in general. DNA labeling assay, functional assays, and morphological mechanism-based assays detect and quantify the cellular events, some of which are specifically associated with apoptotic cell death, such as formation of apoptotic antibodies, expression of apoptotic inhibitors, caspase activation in either intrinsic or extrinsic pathways, and DNA fragmentation. The principles for each assay are given in the respective yellow boxes. Abbreviations: MTT (3-(4, 5-dimethylthiazolyl-2)-2, 5-diphenyltetrazolium bromide), LDH lactate dehydrogenase, BrdU bromodeoxyuridine, PARP polyadenosine diphosphate-ribose polymerase, PS phosphatidylserine


Fig. 3.41 Summary of regulated necrotic cell death. (a) Necroptosis elicited by DR, TLR, and viruses stimulates RIPK3 and then MLKL, which is required for membrane disruption. (b) Pyroptosis induced by GSDMD following its cleavage by CASP1 and CASP11. The main elicitors: PAMPs and DAMPs, or cytosolic LPS. (c) Ferroptosis is dependent on the balance between ROS production due to iron accumulation and antioxidant defense mechanisms that inhibit lipid peroxidation. The ACSL4–LPCAT3–ALOX15 pathway mediates lipid peroxidation, while system xc- (comprising SLC7A11, GPX4, and NFE2L2) impeded this process. (d) NETosis is triggered by NET leakage, which is mediated by ROS generation and histone citrullination. (e) Methuosis is associated with macropinocytosis. Nascent micropinosomes fused forming large vacuoles that contain late endosomal markers (LAMP1 and Rab7). These do not recycle or unify with lysosomes causing cell death. Reproduced with permission (CCBY) from Tang et al. [145]. DR death receptor, TLR Toll-like receptor, RIPK3 receptor-interacting protein kinases 3, MLKL mixed-lineage kinase domain-like protein, GSDMD gasdermin D, CASP1 caspase 1, CASP11 caspase 11, PAMPs pathogen-associated molecular patterns, DAMPs damage-associated molecular patterns, or cytosolic, LPS lipopolysaccharide, ACSL4 acyl-CoA synthetase long-chain family member 4, LPCAT3 lysophosphatidylcholine acyltransferase 3, ALOX15 arachidonate lipoxygenases (ALOXs, specifically ALOX15), SLC7A11 the catalytic subunit solute carrier family 7 member 11, GPX4 glutathione peroxidase 4, NFE2L2 nuclear factor erythroid 2-like 2, NET NETosis extracellular trap, ROS reactive oxygen species, LAMP1 lysosomal associated membrane protein 1, Rab7 lysosomal Rab protein 7. (Adapted from Tang et al. [145])


Fig. 3.42 Methodology for 2D (Puck) and 3D clonogenic curves. The clonogenic assay measures the ability of single cells to form colonies. A cancer cell that is not able to form a colony can be regarded as inactivated. Cellular monolayers are dissociated into single cells and counted and diluted to the required concentration, depending on the dose. The cells are then seeded in cell flasks/dishes for colony formation or in a 3D matrix for spheroid formation. After irradiation, the cells are incubated for 1–3 weeks depending on the cell doubling time of that particular cell line, before they are fixed, stained, and counted. The surviving fraction is calculated as the number of colonies in irradiated samples relative to the plating efficiency of unirradiated control dishes


Fig. 3.43 In vivo assays. Four in vivo animal assays to assess clonogenic capacity after irradiation have been important for radiobiology. (1) The jejunum crypt assay measures the regenerative ability of jejunal crypts after high doses of irradiation. The animals are sacrificed 3.5 days after irradiation, and the numbers of regenerating crypts per circumference are measured. One regenerating crypt corresponds to one surviving clonogenic cell. (2) The skin clone assay used pre-irradiation with a high dose in a ring (moat) around the test skin area to avoid migration of neighboring cells into the test area. The test area is then irradiated, and the number of regrowing skin nodules per cm2 is counted. (3) The spleen colony assay uses transplants of bone marrow cells from an irradiated donor animal. These cells are transferred to recipient animals who have previously been irradiated with a high dose to kill all their own bone marrow cells. After 10–11 days, the recipient animals are sacrificed and their spleens are analyzed for colony-forming units arising from the implanted single cells. (4) The kidney assay uses the same animal for irradiation and control. One kidney of each animal is irradiated, and 60 weeks later, the animals are sacrificed. The number of intact kidney tubules is then counted in both kidneys, and the irradiated kidney can be compared to the unirradiated one


Fig. 3.44 Overview of oncogenes and tumor suppressor genes’ function and regulation


Fig. 3.45 Connexins and gap junctions. Each connexin (a) consists of four transmembrane domains. Six connexins form a hexameric torus called connexon (b). Depending on the composition, connexons are called homomeric (six equal connexins) or heteromeric (up to six different connexins). (c) When the cells form direct contact, the connexons stick together forming gap junctions. Here, the differentiation is made between homotypic channels (both connexons are the same) and heterotypic channels (different connexons). (Reproduced with permission (CCBY) from Totland et al. [163])


Fig. 3.47 Radiation affects key cells involved in initiation and maintenance of inflammation


Fig. 3.46 Membrane connections. Microscopic image of membrane label of cells connected by a tunneling nanotube transporting a gondola and an epithelial bridge containing vesicles and cytoplasmic material. Scale bar: 10 μm. EP epithelial, TNT tunneling nanotube


Fig. 3.48 Mechanism of CRISPR-Cas9 to produce a DNA double-strand break. The CRISPR-Cas9/single-guide RNA (sgRNA) complex consists of the Cas9 protein, which is coupled to the sgRNA, consisting of the transactivating crRNA (tracrRNA), responsible for binding of the RNA complex to Cas9 and the CRISPR RNA (crRNA) which encodes the target sequence. The CRISPR-Cas9/sgRNA complex binds to the specifically targeted DNA sequence and induces a DSB. (Adapted with permission (CCBY) from Zhao et al. [178])


Fig. 3.49 (a) miRNAs and cellular radioresistance: a summary representation of miRNAs in different cancers (outer circle) that regulate various mRNA targets (middle circle). These mRNA targets in turn influence various crucial biological pathways (inner circle) responsible for cellular radioresistance. Data for the figure acquired and modified from Ebahimzadeh et al. [192] (data taken with permission); [193] (CCBY). Gene names: P21 cyclin-dependent kinase inhibitor 1, AIFM3 apoptosis-inducing factor mitochondria-associated 3, APAF1 apoptotic peptidase-activating factor 1, BRCA1 breast cancer gene 1, p53 TP53 gene and tumor protein p53 gene, RB retinoblastoma protein, TCEAL7 transcription elongation factor A-like 7, PTEN phosphatase and tensin homolog, APAF1 apoptotic peptidase-activating factor 1, MTOR mechanistic target of rapamycin kinase. miR microRNA, NSCLC non-small cell lung cancer, GBM glioblastoma, CRC colorectal cancer, HCC hepatocellular carcinoma, NPC nasopharyngeal carcinoma, OSCC oral squamous cell carcinoma. (b) miRNAs and cellular radiosensitivity. A summary representation of miRNAs in different cancers (outer circle) that regulate various mRNA targets (middle circle). These mRNA targets in turn influence various crucial biological pathways (inner circle) responsible for cellular radiosensitivity. Data for the figure acquired and modified from Ebahimzadeh et al. [192] (data taken with permission); [193] (CCBY). Gene names: STAT3 signal transducer and activator of transcription 3, CDK4 cyclin-dependent kinase 4, MCL1 MCL1 apoptosis regulator, BCL2 family member, SIRT1 sirtuin 1, E2F1 E2F transcription factor 1, P21 cyclin-dependent kinase inhibitor 1, EGFR epidermal growth factor receptor, BCL2 BCL2 apoptosis regulator, LDHA lactate dehydrogenase A, ATM ataxia-telangiectasia mutated, AKT AKT serine/threonine kinase 1, H2AX H2A histone family, member X, Beclin-1 coiled-coil, moesin-like BCL2-interacting protein, ATG12 autophagy-related protein 12, TP53INP1 tumor protein p53 inducible nuclear protein 1, DRAM1 DNA damage-regulated autophagy modulator 1, UBQLN1 ubiquilin 1, DUSP10 dual-specificity phosphatase 10, STMN1, stathmin 1, c-MYC Myc-related translation/localization regulatory factor, WNT2B wingless-type MMTV integration site family, member 2B, WNT wingless-type MMTV integration site family, member, PKM2 pyruvate kinase isozymes M1/M2, LDHA lactate dehydrogenase A, MTOR mechanistic target of rapamycin kinase. miR microRNA, NSCLC non-small cell lung cancer, NK/T-cell lymphoma natural killer/T-cell lymphoma, SCC squamous cell carcinoma, ESCC esophageal cancer, GBM glioblastoma; CRC colorectal cancer, HCC hepatocellular carcinoma, NPC nasopharyngeal carcinoma, OSCC oral squamous cell carcinoma, DSB double-strand breaks


Fig. 3.50 Principal steps in exosome biogenesis. The early endosomes, which are generated at the plasma membrane (1), later undergo maturation, called late endosomes or multivesicular bodies (MVBs) (2). The MVBs’ membrane invagination results in the formation of intraluminal vesicles (ILVs). During the invaginating process, particular proteins are incorporated into the invaginating membrane. Other cytosolic biomolecules, i.e., nucleic acids and proteins, are engulfed and enclosed within ILVs. The release of exosomes into the extracellular environment happens after fusion of the MVB with plasma membrane (3)


Fig. 3.51 Graphical depiction of major cellular functions containing the most frequently appearing genes of the highest performing human signatures adapted with permission (CCBY) from Zhao et al. [241]. Genes common among these signatures (white lettering) are indicated in pathways which contain products that these genes interact with (black lettering)


Fig. 3.52 Low-dose hyper-radiosensitivity (HRS) and increased radioresistance (IRR) in T-47D breast cancer cells. The left panel shows a full dose-response curve. The right panel shows the low-dose region. Below about 0.3 Gy, the cells appear to proceed from G2 to mitosis without repair of DNA damage, leading to a steep decrease in survival with dose. For doses above a threshold around 0.3 Gy, the damage is repaired increasingly with dose until the surviving fraction follows the linear-quadratic response curve. The transition dose corresponds to approximately 8–10 double-strand breaks. The dashed line shows a curve fit by the linear-quadratic model, and the solid line by the induced repair model (see Chap. 4)


Fig. 3.53 Path to “increased radioresistance” or “hyper-radiosensitivity.” Cells irradiated with doses below about 0.3 Gy while in G2 will not have enough ATM activated by serine 1981-phosphorylation to reach the threshold level for activation of the early G2 checkpoint. They therefore follow the alternative in the left column, which does not give extra time for repair before mitosis resulting in “hyper-radiosensitivity” (HRS). Cells irradiated with doses above 0.3 Gy while in G2 follow the alternative in the right column and thereby are given more time for repair before mitosis resulting in “increased radioresistance” (IRR)


Fig. 4.1 Kerma in relation to interactions between ionizing photons and matter in a unit mass volume


Fig. 4.2 Schematic of the basic elements of an ionization detector


Fig. 4.3 Signal response to ionization as a function of the applied voltage for heavily ionizing (top curve) and weakly ionizing particles (lower curve). In the Geiger region, the output does neither depend on the voltage nor on the amount of deposited energy or initial ionization. [Adapted from Fig. 4.12 Martin and Shaw (2006). Copyright (2006), Wiley Publishers]


Fig. 4.4 Schematic of a multi-wire proportional chamber [6, 7]


Fig. 4.5 Schematic diagram of a photomultiplier tube (PMT) (courtesy of Physics Libretexts, Fig. 31.2.3)


Fig. 4.6 (a) Schematic of a p–n junction diode operated in forward and reverse bias. (b) Operating characteristics of the diode in forward and reverse bias


Fig. 4.7 Operation of a semiconductor particle detector (a) where an incident proton causes the promotion of one or more electrons from the valence to the conduction band within the detector (b)


Fig. 4.8 (a) Passage of a charged particle through a medium of refractive index n at velocities that polarize the medium. (b) The generation of coherent light waves via the Cerenkov effect. (c) The formation of a cone of Cerenkov light along the path of the charged particle through a medium with positive and (d) negative refractive index. [Taken from Shaffer et al., Nature Nanotechnology, 12, 106–117 (2017). Copyright Springer Nature]


Fig. 4.9 (a) A particle shower within a calorimeter; (b) a particle shower caused by the incidence of a photon on a calorimeter


Fig. 4.10 Schematic representation of the cross-section for a target with Ntarget = 9 and an irradiated surface S


Fig. 4.11 The same microdosimetric spectrum represented through the raw counts per channel acquired (a), counts as a function of the lineal energy (y) after a channel calibration (b), converted into lineal energy frequency (c) and dose (d) distributions


Fig. 4.12 Schematic representation of the different processes leading to the damage produced by irradiation in the cells and their characteristic times


Fig. 4.13 Spatial and temporal evolution of the radiolysis products of a 1 keV electron in liquid water computed by Monte Carlo simulation (Geant4-DNA)


Fig. 4.14 Example of DNA target geometrical model used in the mechanistic simulation of DNA radiation-induced damage with the Geant4-DNA code [48]. The generation of this geometrical model was done with the DNAFabric software [77] from the nucleotide description to the complete genome of an eukaryotic cell nucleus in the G0/G1 phase


Fig. 4.16 Schematic view of a single cell microbeam for radiobiological research using ions. The ions are produced in the ion source and accelerated. Energy selection is carried out with a 90° magnet. Into the focus of this magnet, the aperture needs to be placed, which defines the object that is focused by the focusing unit. The biological sample is placed in its focus. Either in front or behind (shown here) the sample, the ion detector counts the ions and gives the signal to the control unit. Here the signal is processed and the beam switch and scanning unit can be regulated


Fig. 4.17 One assumes that the target only consists of a small area of the object being irradiated. The object may be a macromolecule or an organism


Fig. 4.18 The relationship between the predictions of the single-hit single-target model on cellular survival versus radiation dose [here N/N0 from Eq. (4.27) is replaced by S/S0 or the ratio of cell survival at any dose D to that at 0 Gy]


Fig. 4.19 The relationship between the predictions of the multi-hit single-target model on cellular survival S and radiation dose. S0 is the plating efficiency of the unirradiated controls


Fig. 4.20 Illustration of LQ curves for high and low α/β ratios. For the low α/β, the shoulder of the curve is more pronounced. The α/β-ratio can be found by drawing a line with the initial slope (α) of the curve and finding the dose where the contribution from the linear and the quadratic terms are equal


Fig. 4.21 Low dose hypersensitivity showing a clear downward bend on the survival curve for doses below 1 Gy, followed by an “increased radio resistance” at doses above 2 Gy. The image also shows the key parameters for the linear quadratic modification


Fig. 4.22 Difference in the surviving fraction predicted by the LQ and the LQL model for cell lines with different radiosensitivity (alpha/beta ratio)


Fig. 4.23 The surviving fraction of V-79 Chinese hamster cells irradiated either with a single dose or with two dose fractions separated by 18.1 h. The first dose fraction of 5.05 Gy was given at time 0 and then the cells were incubated for 18.1 h at 37 °C before the second dose fraction (varied between 2 and 8 Gy) was given. As seen, the incubation time between the two dose fractions has led to a complete reconstitution of the curve shape. The explanation was that through repair of the sublethal damage induced by the first dose fraction, the cells had regained their sublethal damage potential. Unrepaired, these damages would have added to the new sublethal damages and become lethal [130]. (Adapted with permission from Springer Nature: Elkind and Sutton, X-ray damage and recovery in mammalian cells in culture. Nature, 1959)


Fig. 4.26 A cartoon to illustrate the difference in sparing effect of fractionated irradiation versus acute irradiation for two cell types having dose-response curves with a broad (late-responding tissues, panel (a) compared to a small (early-responding tissues, panel (b) shoulder region. The small insert shows the curve shapes after acute irradiation to compare. In conclusion, even if cells characterized by a broad-shouldered dose-response curve are the most sensitive ones to high acute doses, these cells are the most resistant ones to fractionated or low dose rate irradiation


Fig. 4.24 Chinese hamster V79-cells were irradiated with two dose fractions separated by different time spans (lower abscissa) and with different temperatures in the incubator between dose fractions; respectively 3, 24, and 37 °C. In particular, the curves representing 37 and 24 °C are of interest since the first one represents cells that cycle between the dose fractions while the other one represents cells, which do not cycle between the dose fractions. (Adapted from [131] with permission, © 2022 Radiation Research Society [131])


Fig. 4.25 The increased cell survival with increasing time between two dose fractions (up to 2 h) is due to increased time for repair of the sublethal damages induced by the first dose fraction. After about 2 h, all sublethal damage has been repaired. Most surviving cells after the first dose fraction would however be in late S or mid G1, the phases where cells are most radio resistant. If cells are offered optimal growth conditions between the dose fractions (37 °C), these surviving cells will continue cell cycle progression and may after 6 h reach a phase where they are more radiosensitive. If the second dose fraction is given at that instant, the survival will be reduced. Therefore, the curve bends downwards between 4 and 6 h, before an upwards turn between 6 and 8 h, when the cells have proceeded to a phase of higher resistance. After a long time, which depends on cell doubling time (typically >12 h), cell division results in an increased multiplicity of the colony-forming units and we see an increased survival that is caused by repopulation. Curve extracted and generalized from Fig. 4.24


Fig. 4.27 The effect of dose rate on the cell survival curve. Repair processes are the primary mechanism that adjusts survival curves as the dose rate decreases from an acute level (~1 Gy/min) to a low level (~0.8 Gy/h). An increase in the slope of the cell survival curve (indicating an increase in radiosensitivity, the “inverse dose rate effect”) occurs due to the redistribution of cells throughout the cell cycle when the dose rate further decreases from ~0.8 Gy/h to 0.37 Gy/h. Finally, increased proliferation of cells occurs as the dose rate decreases further towards a threshold or critical dose rate, which varies by cell type. Notice that this cartoon presents a very special case of a cell type having an inverse dose rate effect, which is probably associated with a simultaneous lack of both p53- and pRB-function. The dose rate that can produce a hormetic effect is unclear and not indicated, but is several orders of magnitude lower than the lowest one depicted here (0.37 Gy/h)


Fig. 4.28 Mice of age 9–11 weeks were given fractionated irradiation with 240 kV X-rays to the dorsal trunk over a period of 3 weeks (i.e., more than one fraction per day for regimes with 32 and 64 fractions). Chromium-51-ethylene-diamine-tetra-acetate ([51Cr]-EDTA) was injected intraperitoneally (i.p) 26 weeks after completed irradiation and the blood level of radioactivity was measured in blood samples taken 60 min after injection. Increasing blood levels indicate reduced kidney filtration capability and the red line indicates an isoeffect level of reduced kidney function. [Modified from [136] with permission [136], © 2022 Radiation Research Society]


Fig. 4.30 In (a), the data of Fig. 4.28 on late-responding mouse kidney are replotted as isoeffect tolerance curves with total tolerated dose in a fractionation scheme as a function of the dose per fraction (both axes logarithmic). In (b), similar data are shown for an early-responding normal tissue, namely mouse skin. Notice that the α/β-dose is 3 Gy for the late-responding tissue and 12 Gy for the early-responding tissue. (Reprinted with permission from [137])


Fig. 4.29 The isoeffect data defined by the red line in Fig. 4.30 are replotted after the two transformations described by Eqs. (4.45) (plotted in panel a) and (4.46) (plotted in panel b). Reprinted with permission from [137]


Fig. 4.32 The curves indicate what extra radiation dose is required to counteract only proliferation during treatment with one daily dose fraction in two different rodent tissues. Human tissues react more slowly than rodent tissues. Thus, the time for increased proliferation therefore would probably start at a later time than indicated in the figure for corresponding human tissues. (Adapted with permission from [139])


Fig. 5.1 The benefit/risk balance. The objective of RT is to control the tumor while sparing normal tissues, to ensure the patient’s cure without unacceptable side effects


Fig. 5.2 Illustration of the therapeutic window. For an identical delivered dose, the curves show the difference between tumor control probability and normal tissue complication probability and methods to widen the window. (Reprinted from Drug radiotherapy combinations: review of previous failures and reasons for future optimism; Figure from Higgins et al. [12], with permission)


Fig. 5.3 Prolongation of the overall treatment time narrows the therapeutic window. Conventional irradiation course in 6 weeks versus a split-course course in 10 weeks. (Adopted from [16])


Fig. 5.4 Fractionation as an effective method to widen the therapeutic window. Curves schematically represent the probability of normal tissue side effects (NTCP, red curve), the probability of tumor control (TCP, blue curve) as well as the complication free tumor control curve (green) following single-dose radiation (a) and dose fractionation (b). (Figure from Shrieve and Loeffler [17], with permission from Wolters Kluwer Health, Inc.)


Fig. 5.5 Tumor Control Probability (TCP) and radiation dose relationship. The scheme demonstrates the sigmoid relationship of probability of tumor control and normal tissue damage to radiation dose


Fig. 5.6 The response of clonogenic tumor cells at 2 Gy/fraction as a function of the total dose. Assuming that each 2 Gy fraction reduces the clonogenic cell population with 50%, 30 fractions of 2 Gy will reduce 1010 clonogenic tumor cells to ten surviving cells. In order to eliminate each clonogenic tumor cell, additional fractions of 2 Gy are required to reach tumor control


Fig. 5.7 The Hallmarks of Radiobiology, the 6R’s


Fig. 5.9 Simplified illustration of the reoxygenation process. Tumor cell compartments include anoxic, hypoxic, and aerated cells. Most tumors show a heterogeneous pattern of hypoxia with gradients of oxygen pressure decreasing with increasing distance from blood vessels. The oxygen status of the tumor cells is not constant; it is a dynamic, constantly changing phenomenon. Following exposure to irradiation, well-oxygenated cells will be sterilized, but many hypoxic cells will not. During the course of fractionated RT hypoxic cells can be reoxygenated, and therefore become sensitive to radiation and can be sterilized. (Figure was adapted from [13])


Fig. 5.10 Illustration of the steps of radiation-induced systemic immune activation contributing to attack on distant/metastatic tumor cells


Fig. 5.11 The dose rate effect seen as an extreme form of fractionation. Cell survival following fractionated HDR irradiation with increasing number of fractions (solid curves). With an infinite number of tiny fractions, and complete sublethal damage repair, the dose-squared β parameter of the LQ tends to zero, and only the dose-linear β parameter plays a role. Then, the Biologically Effective Dose (BED) is reached for a certain endpoint effect E. Similar sparing phenomenon with decreasing dose rate in continuous LDR exposure (dotted curves)


Fig. 5.12 Illustration single-track action and double-track action. In single-track action, the two interactive lesions are produced by a single track of ionization induced by an X-ray photon that subsequently produces a dose which is independent of dose rate and linearly proportional to dose. In double-track action, the two interactive lesions are produced by a different track of ionization induced by X-rays which subsequently produces a dose which is dependent on the dose rate (decreasing the dose rate reduces double-track action) and non-linearly proportional to the radiation dose squared


Fig. 5.8 The cell-cycle phase and radiation sensitivity. Cell survival curves of V79 Chinese hamster cells irradiated at different phases of the cell cycle on the left side


Fig. 5.14 The inverse dose rate effect. When the dose rate delivered to HeLa cells is decreased from 1.54 to 0.37 Gy/h, the efficiency of cell killing increases, with damage generated similar to that from an acute exposure [35]. When cells are exposed to higher dose rates, they are kept in the phase of the cycle in which they are at the beginning of irradiation. However, use of lower dose rates may allow cells to continue cycling during irradiation. When cells are exposed to 0.37 Gy/h, cells tend to progress from other phases of the cell cycle and arrest in G2, which is a radiosensitive phase of the cycle. As a result, an enriched population of G2 cells is responsible for increasing the radiosensitivity of cells


Fig. 5.15 Review of classical biomarkers used to obtain information on relevant features of radiobiology


Fig. 5.16 Review of modern biomarkers used to obtain information on relevant features of radiobiology


Fig. 5.17 Schematic view of biomarkers. Proteins, DNA chromatin, DNA, or RNA that are analyzed by proteomics, genomics epigenomics, genomics, or transcriptomics, respectively


Fig. 5.18 Diffusion of oxygen through tumor. As the distance from the blood supply increases, the oxygen levels available for the cells decreases. As the cells grow more hypoxic, they become more radioresistant


Fig. 5.19 Description of the tumor biological responses to radiation and the mechanisms for its resistance


Fig. 5.20 Review of tumor suppressors and the molecular signal pathways that contribute to radioresistance


Fig. 5.21 An overview of a typical EMT program that causes cadherin shifts in the cell and invasion of cancers


Fig. 5.24 Radiation-induced chronic damage to healthy tissues. Late damage develops within months to decades post RT and may concern all normal tissues. Successive cycles of tissue remodeling and repair, together with chronic inflammation induce vascular and parenchymal damage leading to tissue atrophy/fibrosis/necrosis compromising organ function


Fig. 5.25 3D RT isodose curves


Fig. 5.26 Irradiation and progression of radiation-induced normal tissues damage. Tissue damage results from several acute events such as cell loss and endothelial cells activation. Damage progression includes a continuum of effects orchestrated in time and space leading to tissue fibrosis/necrosis and organ dysfunction


Fig. 5.27 NTCP curves calculated from Lyman-Kutcher-Burman model for two parameters combinations. Parameter m is inversely proportional to the steepness of the curve. (a) NTCP curve calculated by LKB model for D50 = 50 Gy and m = 0.50. For a dose of 50 Gy, the value of NTCP is 0.50. (b) NTCP curve calculated by LKB model for D50 = 60 Gy and m = 1. For a dose of 50 Gy, the value of NTCP is 0.43


Fig. 5.28 Ionizing radiation and factors associated with cancer stem cells and tumor microenvironment contribute to tumor resistance to IR. (Adapted from [240, 260])


Fig. 5.29 From microbiota healthy state to dysbiosis and pathologies: case of RT effects


Fig. 5.30 Typical radiomics workflow. The different steps are: (1) Data selection: choosing the image to analyze, the imaging protocol to use and the correlated outcome. (2) Imaging and segmentation with (semi-) automatic methods to improve reproducibility. (3) Feature extraction and selection with appropriate algorithms. (4) Modeling using available machine learning models. (5) Reporting results. (Adopted from Keek et al. [322] with permission)


Fig. 6.1 Comparison of the relative depth dose distribution of 15 MeV electrons (green), 250 MeV electrons (purple), 2 MeV photons (red), 150 MeV protons (dark blue), and 250 MeV/u carbon (turquoise) and cobalt 60 (orange)


Fig. 6.2 Fractionation regimen used in clinical practice. (Reproduced with permission from [3])


Fig. 6.3 Predicted TCP values by the DD model (solid curves) as a function of the number of fractions delivered, for stage T1/2 head and neck cancer (HNC) patients. Dose per fraction (fx): 1.8 Gy (blue), 2.0 Gy (red) or 2.4 Gy (black), administered daily, 5 fx/week. NTCP late predictions for late toxicity (dashed curves) were made with the standard LQ model normalized to a 13.1% value (grade 3–5 late toxicity at 5 years) for 35 × 2 Gy fractions. The solid circles represent current standard treatment regimens. Thus, the final week of 5 fractions could be eliminated without compromising TCP, but resulting in significantly decreased late sequelae due to the lower total dose. (Reproduced with permission from [9])


Fig. 6.4 Temporal evolution of the treated lesion: (a) before treatment with the limits of the PTV delineated in black; (b) at 3 weeks, at the peak of the skin reaction (grade 1 epithelitis NCI-CTCAE v 5.0); (c) at 5 months. (Reproduced with permission from [33])


Fig. 6.5 Overview of radiotherapy combinations influencing different hallmarks of cancer


Fig. 6.6 Radiotherapy has multiple immune stimulating and immune suppressive effects which depend on dose


Fig. 6.7 Prospective direct genomic effect of estradiol, tamoxifen, and IR on inhibition of cell cycle progression. (Reproduced with permission from [86])


Fig. 6.8 Mild hyperthermia enhances radiotherapy by initiating multiple intracellular and intercellular processes. While radiotherapy induces DNA damages, hyperthermia can enhance the induction of radiation-induced DNA damage by increasing the perfusion and reoxygenation; hyperthermia can temporarily inhibit the DNA repair processes which causes cell cycle arrest and subsequently cell death of the tumor cells such as apoptosis; hyperthermia can also trigger an immune response and disturb the tumor microenvironment eventually all causes of increased tumor cell kill


Fig. 6.9 Improved clinical responses after addition of hyperthermia in superficial tumor types. In malignant melanoma, superficial breast cancer and head and neck squamous cell carcinoma, complete responses were much better in patients treated with RT combined with hyperthermia, compared to RT alone. In soft tissue sarcoma, the addition of RT plus hyperthermia to neoadjuvant chemotherapy, leads to a8.6% higher 10-year overall survival


Fig. 6.11 Schematic view of spatial fractionation in RT. The blue object represents the tumor


Fig. 6.12 Quadratic (a) and hexagonal (b) pencil minibeam and planar minibeam (c) arrangements on a 2D lattice with view direction in the direction of the beam. The dose is color coded and normalized to a mean dose D0. The black lines indicate the unit cell, and the white lines indicate the corresponding ctc. (Reproduced with permission from (CCBY) [112])


Fig. 6.13 Treatment planning of a lung tumor patient in LATTICE (a) and GRID (b) therapy. (Reproduced with permission from [114])


Fig. 6.14 Cerebellum of a rat 8 h after exposure to synchrotron MRT. The peak dose was 350 Gy, and each microbeam was 25 μm wide and spaced 200 μm from the center of the next microbeam. (a) H&E staining of the cerebellum. The track of the microbeams can be seen as two vertical bands of dark blue dots (yellow arrows) consisting of cells with nuclear pyknosis (irreversible condensation of chromatin in the nucleus of cells undergoing necrosis). (b) Immunostaining of a different section of the cerebellum with gamma-H2AX. The track of the microbeam can be seen as green staining, indicating large amounts of DNA damage. The blue color indicates nuclear staining with DAPI


Fig. 6.15 (a) Beam width for proton, helium, and carbon ion beams with penetration depth. No incident beam size and divergence is used, both have to be added to the FWHM. (b) Widening of a helium ion and a proton beam with penetration depth


Fig. 6.16 Conceptual therapy plans comparing conventional proton therapy (homogeneous) with pMBRT (Minibeam) for a box-shaped tumor


Fig. 6.18 (a) Treatment plan comparison of a meningioma patient. Plan 1 and 2 are homogeneous plans, with different planning methods. Plan 3 and 4 show single field pMBRT plans with ctc of 4 mm and 6 mm, respectively. (b) Comparison of dose-volume histograms for plan 2 (homogeneous, dashed line) and plan 3 (pMBRT, solid line)


Fig. 6.19 90Y-resin microspheres radioembolization treatment course. Example of a patient treated for neuroendocrine neoplasia


Fig. 6.20 Schematic representation of the structure of a radiopharmaceutical. The purple circle represents the cancer-targeting moiety, which can be a peptide, small molecule, or antibody. This targeting moiety is connected to a chelator (blue circle) entrapping a radionuclide (for diagnostics or therapy) directly to the targeting moiety or via a linker molecule (grey)


Fig. 6.21 Overview of the general principle or radioligand therapy. A radionuclide (either ingested orally or injected systemically) will enter the bloodstream. Via the bloodstream, the radionuclide will find its way to the target tissue either through its natural affinity for the target tissue (i.e., the natural affinity radionuclides) or via expression of certain molecules on the target tissue (i.e., vectorized radionuclide therapy)


Fig. 6.22 Hypothetical representation of time-activity curves (TACs) of a vector radiolabeled with a diagnostic (T1/2 = 30 min) and therapeutic radionuclide (T1/2 = 6 h)


Fig. 6.23 Schematic representation of the structure of the PSMA-targeting compound PSMA-617. The blue circle shows the PSMA-targeting moiety. The purple circle highlights the DOTA-chelator used to entrap radionuclides. The grey circle represents the linker molecule that connects the PSMA-targeting moiety with the DOTA-chelator


Fig. 6.25 Overview of combination therapies with radionuclide therapy


Fig. 6.26 (a) Absorbed dose of a 121 MeV proton in water forming the Bragg peak [174]. (b) Spread Out Bragg Peak formed by overlaying ions with different energy forms the spread out Bragg peak as used for therapy [175]. (c) Dose distribution of one patient with locally advanced non-small cell lung cancer (NSCLC) planned with intensity-modulated radiation therapy (IMRT) (left) or protons (right), depositing no dose behind the tumor [176


Fig. 6.30 (a) Principle of a classical cyclotron. (b) Hill-valley magnet design


Fig. 6.27 Schematic representation of gH2AX after exposure to carbon ions versus photons. DAPI in blue, gH2AX in green


Fig. 6.28 Schematic representation of the relationship between OER and RBE in function of LET


Fig. 6.29 Summary comparison between photon irradiation and carbon ion irradiation


Fig. 6.31 (a) Principle of a synchrotron. (b) A positively charged beam coming from the front is deflected by Dipole magnets and focused by quadrupole magnets


Fig. 6.32 (a) Linear acceleration principle. (b) A proton LINAC system. (c) Principle of a side-coupled drift tube LINAC (SCDTL) structure (cut through). (d) Principle of a coupled cavity LINAC structure (cut through)


Fig. 6.33 The versatility of nanoparticles and their potential applications in cancer therapy


Fig. 7.1 Characteristics to determine an ideal biomarker. An ideal biomarker for molecular epidemiological studies (top) and general considerations of a good biomarker (bottom)


Fig. 7.2 Biological classification of radiation biomarkers. (Reproduced with permission, with some modification (changed layout and some content), from [10]; licensed under CC BY-NC-ND 3.0)


Fig. 7.3 Timeline of radiation-induced disease progressions and relation with different types of radiation biomarkers. (Reproduced with permission, with some modification (changed color and layout), from [10]; licensed under CC BY-NC-ND 3.0)


Fig. 7.4 Brief overview of the original clonogenic assay


Fig. 7.5 Patient tissue biopsy sample types and different modalities of analysis that can be performed to identify predictive biomarkers of RT treatment response


Fig. 7.6 Schematic of clinically informative elements obtained by liquid biopsy and various analysis methods. (Reproduced with permission from [40])


Fig. 7.7 Basic schematic of a Raman spectrometer


Fig. 7.8 G2 chromosomal radiosensitivity assay. Chromatid breaks after 1 Gy of γ-irradiation as visualized at a metaphase peripheral blood lymphocyte from a healthy donor where four chromatid breaks are observed. (Reproduced with permission from [128])


Fig. 7.10 Schematic representation of the relationship between the relative susceptibility and the age at exposure. (Reproduced with permission from [133])


Fig. 7.11 Age-related cellular changes that may influence radiosensitivity and their mechanistic interplay. Compared to young cells, aged cells present increased impaired DNA damage repair, telomeres attrition, increased oxidative stress, and additional epigenetic alterations


Fig. 7.12 Summary of biological sex-dependent health risks induced by radiation exposure. (Reproduced with permission from [149])


Fig. 7.14 Overview of DNA damage and repair pathways and most common genetic disorders


Fig. 8.1 External exposure and contamination


Fig. 8.2 Non-malignant conditions most commonly treated with radiation therapy as a percentage of all international radiotherapy institutes surveyed (n = 508). (Data extracted with permission from [6])


Fig. 8.4 Global trends in the number of monitored workers, and in collective effective doses and effective doses to workers for different practices of the nuclear fuel cycle. (Reproduced with permission from [1])


Fig. 8.5 International Nuclear Event scale based on severity and impact of the incident


Fig. 8.6 Approximate prompt and delayed (fallout) effects from a 10-kT detonation. (Reproduced with permission from Lawrence Livermore National Laboratory)


Fig. 8.7 Relationship between ionizing radiation induced tissue effects and fetal/embryo stage of development. (Reproduced with permission from [30])


Fig. 8.8 Examples metaphase spreads with (a) dicentrics tri-centrics and several fragments and (b) with a translocation. These aberrations result from the fusion of sections of broken chromosomes


Fig. 8.9 Protein fiber and cellular organization within the lens. (a) The lens is formed from a single cell layer of lens epithelial cells (LECs) that covers the anterior portion of the lens. The cells in the central region are mostly quiescent; meanwhile the proliferating cells are largely confined to the germinative zone (GZ) in the equator of the lens. After division, LECs migrate to the transitional zone (TZ), situated immediately adjacent to the GZ and most distal to the anterior pole. In the TZ, LECs begin differentiation to form lens fiber cells (LFCs) that comprise the bulk of the lens mass. They enter the body of the lens via the meridional rows (MRs), adopting a hexagonal cross-sectional profile, offset from their immediate neighbors by a half cell width to deliver the most efficient cell–cell packing arrangement that is perpetuated into the lens body as LECs continue their differentiation and maturation process into LFCs. (b) The lens sits in the anterior portion of the eye where it focuses light onto the retina to create a sharp image (top). However, when a cataract develops, the transmission of light is either blocked or not focused correctly (bottom), creating a distorted image. (c) Example of lens fiber sutures as viewed from the posterior pole of the lens in the healthy lens compared to a nuclear cataract, similar to that represented in (b). (Reproduced with permission from [35])


Fig. 8.10 Mechanisms of ionizing radiation response observed in human and animal lens epithelial cells or cell lines. Cx connexin, ECM extracellular matrix, FGF fibroblast growth factor, IR ionizing radiation, LEC lens epithelial cell. (Reproduced with permission from [35])


Fig. 8.11 The latency of cataract and Lifelong Cataractogenic Load. (a) Timeline for lens aging. (b) Accumulated cataract load without exposure to ionzing radiation. (c) Accumulated cataract load after exposure to ionizing radiation (Reproduced with permission from [37])


Fig. 8.12 Proposed cell types in the heart, key events and adverse outcomes that may contribute to cardiovascular disease. Not all potential cell types and key events are listed and some of the key events listed may be common across the different cell types. ECM extracellular matrix, MCP-1 monocyte chemoattractant protein-1, NO nitric oxide, PPAR alpha peroxisome proliferator-activated receptor (PPAR)-alpha, ROS reactive oxygen species. (Reproduced with permission from [44])


Fig. 8.14 Scheme showing the phases sequence of the Acute Radiation Syndromes and examples of symptoms


Fig. 8.15 Schema for trauma triage. (Reproduced with permission from [75])


Fig. 8.16 Relationship between time to onset of vomiting and dose between 2 and 10 Gy. (Reproduced with permission from [75])


Fig. 8.17 Lymphocyte depletion with dose and time post exposure, following whole-body doses exceeding 1 Gy. (Reproduced with permission from [75])


Fig. 8.18 (a) Schematic representation of the formation of a dicentric chromosome (dic) after exposure to ionizing radiation with the formation of a chromosome fragment without centromere (ace). (b) Giemsa stained metaphase spread of a human peripheral blood lymphocyte with a dic and ace


Fig. 8.19 Presentation of binucleated cells including 0, 1, 2 or 4 micronuclei


Fig. 8.20 (a) Schematic representation of the formation of a symmetrical translocation after radiation induced chromosomal breaks. (b) FISH painted metaphase spread of a human peripheral blood lymphocyte with translocations indicated by the arrows


Fig. 8.21 (a) Prematurely condensed single chromatid chromosomes following gamma irradiation to 4 Gy as visualized using the PCC assay and lymphocyte fusion to a mitotic CHO cell. Fourteen excess PCC fragments can be scored (shown by arrows). (b) Non-irradiated G0-lymphocyte PCCs demonstrating 46 single chromatid PCC elements. (Reproduced with permission from [112])


Fig. 8.22 (a) Schematic representation of the formation of gamma-H2AX foci. Following radiation-induced DNA breakage, the free DNA ends are labeled by the phosphorylation of H2AX, which can be visualized and quantified using immunofluorescence antibodies. (b) Gamma-H2AX foci in human blood lymphocytes following exposure to 0 or 1 Gy X-rays following a post-exposure incubation for 1 h (40× magnification fluorescence microscopy images showing gamma-H2AX foci in green and DNA counterstain in blue)


Fig. 9.1 Uranium (including uranium 238U and actinium 235U) and thorium decay chains


Fig. 9.2 Natural radionuclides distribution in different environmental compartments


Fig. 9.3 Exposure and effects of different radiation types on organisms


Fig. 9.4 Schematic representation of overall sensitivities of different taxa to acute gamma radiation exposure. (Reproduced with permission of UNSCEAR, adapted from UNSCEAR 2008 report, Annex E)


Fig. 9.5 High and low LET radiation DNA damage effects


Fig. 10.2 Radiation environment during a space mission. (Image courtesy by ESA and reprinted from Chancellor et al. [15] with permission under Creative Commons Attribution-NonCommercial-NoDerivatives License: http://creativecommons.org/licenses/by-nc-nd/4.0/)


Fig. 10.3 GCR composition, as based on data from NASA’s Advanced Composition Explorer (ACE) spacecraft. (Reprinted with permission from http://www.srl.caltech.edu/ACE/ACENews/ACENews83.html)


Fig. 10.4 GCR overall average fluxes versus energy. (Data from Beatty et al. [23])


Fig. 10.5 The active regions (upper left), solar flare (upper right), and coronal mass ejections (CME, lower left and right) of the 28/10/2003 event captured by the Solar and Heliospheric Observatory (SOHO) satellite. The CME was imaged by the Large Angle and Spectrometric COronagraph (LASCO) instrument by blocking the light from the solar disk. (Courtesy of SOHO/EIT and SOHO/LASCO consortium. SOHO is a project of international cooperation between ESA and NASA)


Fig. 10.7 Radiation belts of the Earth. (Figure from Van Allen radiation belt. Reprinted with permission from Wikipedia. Author Booyabazooka at English Wikipedia, https://commons.wikimedia.org/wiki/File:Van_Allen_radiation_belt.svg)


Fig. 10.8 Relative radiation exposure of varying duration during medical procedures (green), specific space missions (purple), and on various celestial bodies (blue). The astronaut yearly and career limits are given in red boxes. For comparison, some facts on radiation exposure of the general population and occupational exposure limits (US) are indicated (gold). (Reprinted with permission from Iosim et al. [43])


Fig. 10.9 Calculated dose equivalent rate in LEO (51.6° inclination, 390 km altitude) as a function of shielding thickness given as area density for different shielding materials: (left) GCR, (right) Van Allen trapped protons. (Data used with permission from Dietze et al. [37])


Fig. 10.10 Scheme for Monte Carlo (MC) calculations of the radiation environment at a planet/celestial body, here in particular Mars. GCRs galactic cosmic rays, SEPs solar energetic particles, p+ protons, He2+ ions helium ions


Fig. 10.11 Schematic view of the particle showers (main particles are plotted here) generated in the downward propagation of primary GCRs particles through the Martian atmosphere and of the backscattered particles [74]


Fig. 10.12 Possible health effects of space radiation exposure


Fig. 10.13 Survival of mammalian cells after exposure to low linear energy transfer (LET) and high-LET radiation. Low-LET radiation includes photons, electrons, positrons, protons, and more. High-LET radiation encompasses heavy ions, and, depending on energy, also He ions and neutrons


Fig. 10.14 As a heavy ion travels through a mammalian cell nucleus, a multiple of ionizations is produced, damaging a chromosome arranged in its nuclear territory several times. Delta rays emanating from the primary track can induce further damage. Therefore, traversal of high-LET radiation through a cell nucleus can produce many breakpoints in chromosomes


Fig. 10.15 Comparison of ionizations (grey dots) in a DNA molecule that are induced by electrons as an example of low-LET radiation and by a high-LET α-particle. The ionizations produced by the α-particle are located densely along the track, with some secondary electrons (δ rays) generated while traversing the cell. This spatial distribution goes along with a higher probability of simultaneously breaking both DNA strands thereby producing a double strand break (DSB), and also further damage to bases and single strand breaks (SSB) in close proximity which is then called complex DNA damage


Fig. 10.16 On 3 November 1957 Laika was the first living mammal that was sent to space onboard the satellite Sputnik 2


Fig. 10.17 Overview of the bdelloid rotifer Adineta vaga life cycle. Bdelloid rotifers live in limno-terrestrial habitats like mosses and lichens. Adapted to these environments, they can be desiccated at any stage of their life cycles including egg stage. When they are exposed to desiccation, adults adopt a “tun” shape allowing optimal desiccation resistance. Adineta vaga is about 200–250 μm long. (Credits B. Hespeels)


Fig. 10.19 View of TARDIS experiment. (a) View of the exobiology Biopan platform containing TARDIS experiment. For 12 days in September 2007, approximately 3000 water bears were launched in space during the Foton-M3 mission. Reprinted with permission from ESA. (b) Details of the sample holder containing the tardigrades Richtersius coronifer. Tardigrades on the top level were exposed to the Sun and were optionally protected with filters. (Image kindly provided by K. Ingemar Jönsson and reprinted with his permission)


Fig. 10.20 View of Rob1 hardware used to culture hydrated A. vaga individuals onboard of ISS (December 2019). Top left: Rob1 hardware after its assembly at the launch site at Kennedy Space Center. Rob1 hardware is a passive hardware containing five culture bags containing hydrated specimens of A. vaga. Hardware enables gas exchanges between rotifer cultures and the outside through a permeable membrane. Top right: View of the culture bags assembled inside Rob1 hardware. Culture bags, loaded with 10,000 A. vaga individuals each, are made of Teflon and ensure an optimal gas exchange between the culture medium and the outside. Bags are waterproof and avoid any leakage of the medium (composed of mineral water and sterile lettuce juice) or rotifers. Reprinted with permission of Marc Guillaume. Bottom left: View of ESA astronaut Luca Parmitano loading two Rob1 hardware on KUBIK. KUBIK is a small incubator, temperature-controlled, with removable inserts designed for self-contained microgravity experiments. (Reprinted with permission of NASA)


Fig. 10.21 View of one Rob2 hardware used onboard of the ISS (left) and Astronauts checking the correct rehydration of A. vaga individuals. Sixteen pieces of hardware were sent to ISS, each containing 40,000 dry rotifers. Once onboard, rotifers were automatically rehydrated and cultivated 11 days before their fixation and download to Earth. (Reprinted with permission of Boris Hespeels and NASA)


Fig. 10.22 A comparison among different responses of Plants (P) and Mammals (M) to ionizing radiation. (Reprinted with permission from Arena et al. [346])


Fig. 10.23 Difference between the different cultures


Fig. 10.24 NASA’s 3D BioFabrication Facility BFF. (Image JSC2019E037579, Credits NASA)


Fig. 10.25 Molecular response experienced by microorganisms in the outer space environment revealed with the help of global and integrative –omics approaches of systems biology that have been recently used to study microorganisms exposed to real and simulated space conditions. (Reprinted with permission from Milojevic et al. [366])


Fig. 10.26 Stress responses experienced by microorganisms in outer space real and simulated conditions, revealed with –omics-assisted investigations. Proteins and genes of stress responses with altered abundance and expression after exposure of microorganisms to the outer space real and simulated environment [366]


Fig. 10.27 Molecular alterations underlying microbial pathogenicity, virulence, and biofilm formation in the outer space environment, resolved with –omics-assisted investigations [366]


Fig. 10.28 Schematic view of the SNAKE (Superconducting nanoprobe for (kern) particle physics experiments) setup, including linear particle accelerator (orange), focusing unit (superconducting magnetic lens) and detection system with the particle detector and ultrafast high-voltage switch


Fig. 10.29 Aerial view and general layout of the NASA Space Radiation Laboratory (NSRL) facility in Upton, NY, USA. EBIS electron beam ion source. (Satellite view courtesy Google Earth)


Fig. 10.30 Three key areas developed to provide the GCR simulator at NSRL. (Source: Simonsen et al. [396], reproduced with permission)


Fig. 10.31 General layout of a linear high-energy particle accelerator. RF radio frequency


Fig. 11.1 Classification of radiomodifiers with their biological properties


Fig. 11.2 The use of radioprotectors, radiomitigators, and radiosensitizers before, during, or after irradiation


Fig. 11.3 Various applications of radioprotectors


Fig. 11.4 Potential mechanism of action of radioprotectors against cell damage due to IR


Fig. 11.5 General therapeutic approaches to develop novel radioprotective agents. IR, directly or indirectly, causes damage to macromolecules such as DNA, lipids, and proteins. As a result, oxidative stress is generated, which either triggers DNA damage repair or induces p53-mediated cell disorders, such as cell cycle arrest and cell apoptosis. When the damage exceeds the cell’s ability to repair itself, the cell appears to follow the death program. The protective activities of potential radioprotectors should target such phases/mechanisms (described in blue dotted box) with the aim to shield the normal cells from harmful insults of irradiation. Inspired from/based on “General principles of developing novel radioprotective agents for nuclear emergency” from Radiation Medicine and Protection (Volume 1, Issue 3, Pages 120–126), by Du et al. 2020, Copyright Elsevier (2022)


Fig. 11.6 Mechanisms of radioprotection by amifostine


Fig. 11.7 Radioprotective properties of cyclic nitroxides include scavenger free radical capacity and SOD-like activity. Adapted from “Nitroxides as Antioxidants and Anticancer Drugs,” by Lewandowski M. and Gwozdzinski K. 2017, Licensed under CC BY 4.0


Fig. 11.8 Radioprotective and biological properties of polyphenols


Fig. 11.9 Radioprotective effects of vitamins


Fig. 11.10 Radioprotection by oligoelements


Fig. 11.11 Nanozymes with SOD-like activities


Fig. 11.12 Effects of Mn porphyrin-based SOD mimics in normal and cancer cells


Fig. 11.13 Radioprotective properties of melatonin


Fig. 11.15 Radiomitigators: mechanism of action


Fig. 11.16 Effect of probiotics, prebiotics, and FMT on the function of the intestinal epithelium and gut microbiome


Fig. 11.17 Role of ACEIs, ARBs, and renin inhibitors in the renin–angiotensin system


Fig. 11.18 Delivery of hydrogen and its protective and therapeutic opportunities in various systems. Adapted from “Molecular hydrogen: A potential radioprotective agent,” by Hu et al. [122, 123], Licensed under CC BY 4.0


Fig. 11.19 Biological compartments for radionuclide intake and distribution. Reproduced from Dainiak N and Albanese J, Assessment and clinical management of internal contamination, JRP, 2022, in press, and modified from ICRP, 2015, Occupational Intakes of Radionuclides: Part 1. ICRP Publication 130. Ann. ICRP 44(2)


Fig. 11.20 Isotopes and focal accumulation in the body


Fig. 11.21 Development of potential radiosensitizers at different levels. Potential radiosensitizers can be developed focusing on the molecular, cellular, or organismic levels, which may be useful in modulating the radiation effects on cancer cells as well as on normal cells


Fig. 11.22 Radiation therapy and nutraceutical substances may influence signaling pathways involved in migration, inflammatory response, autophagy, and formation of reactive oxygen species (ROS). Adapted from “Nutraceutical Compounds as Sensitizers for Cancer Treatment in Radiation Therapy,” by [203], Licensed under CC BY 4.0


Fig. 11.23 Mass energy absorption coefficient (left-hand-side Y-axis) for gold (purple) and soft tissue (blue) as a function of X-ray energy. Right-hand-side Y-axis indicates the ratio (black)


Fig. 11.24 Physical, chemical, and biological mechanisms of nanoparticle. Nanoparticles radiosensitization. Reproduced with permission of Dove Medical Press Ltd., from Application of Radiosensitizers in Cancer Radiotherapy, International Journal of NanoMedicine, 16: 1083–1102, by Gong L et al. 2021


Fig. 11.25 Schematic representation of the possible pathways through which nanoparticles can affect the yield of radicals following radiation exposure: (a) primary water radiolysis, (b) secondary water radiolysis, and (c) radical scavenging from nanoparticles


Fig. 11.26 The advantages and various modes of action by which PARPi enhance the radiosensitivity of tumor cells. Adapted from “Poly-(ADP-ribose)-polymerase inhibitors as radiosensitizers: a systematic review of preclinical and clinical human studies,” by [224], Licensed under CC BY 3.0


Fig. 12.1 Adapted from UNSCEAR 2012, Annex A Schematic of the relationship between dose, additional to that from typical exposure to natural background radiation, and probability of occurrence of health effects, Fig. AV-I p68


Fig. 12.2 Adapted from UNSCEAR 2012, Annex A Schematic of the relationship between dose, additional to that from typical exposure to natural background radiation, and probability of occurrence of health effects, Fig. AV-I p68


Iodine-123 whole body scan for thyroid cancer evaluation. The study above was performed after the total thyroidectomy and TSH stimulation with thyroid hormone medication withdrawal. The study shows a small residual thyroid tissue in the neck and a mediastinum lesion, consistent with the thyroid cancer metastatic disease. The observable uptakes in the stomach and bladder are normal physiologic findings.


Cardiopulmonary exercise test using a  treadmill .


Stress-ECG of a patient with coronary heart disease: ST-segment depression (arrow) at 100 watts of exercise. A: at rest, B: at 75 watts, C: at 100 watts, D: at 125 watts.


Lawrence's 60-inch (152 cm) cyclotron,  c.  1939 , showing the beam of accelerated  ions  (likely  protons  or  deuterons ) exiting the machine and ionizing the surrounding air causing a blue glow


Lawrence's original 4.5-inch (11 cm) cyclotron


Lawrence's 60-inch (150 cm) cyclotron at  Lawrence Radiation Laboratory ,  University of California , Berkeley, California, constructed in 1939. The magnet is on the left, with the vacuum chamber between its pole pieces, and the beamline which analyzed the particles is on the right.


Diagram of a cyclotron. The magnet's pole pieces are shown smaller than in reality; they must actually be at least as wide as the accelerating electrodes ("dees") to create a uniform field.


Diagram of cyclotron operation from Lawrence's 1934 patent. The hollow, open-faced D-shaped  electrodes  (left), known as dees, are enclosed in a flat  vacuum chamber  which is installed in a narrow gap between the two  poles  of a large magnet (right).


Vacuum chamber of Lawrence 69 cm (27 in) 1932 cyclotron with cover removed, showing the dees. The 13,000 V RF accelerating potential at about 27 MHz is applied to the dees by the two feedlines visible at top right. The beam emerges from the dees and strikes the target in the chamber at bottom.


The trajectory followed by a particle in the cyclotron approximated with a  Fermat's spiral


In isochronous cyclotrons, the magnetic field strength  B  as a function of the radius  r  has the same shape as the Lorentz factor  γ  as a function of the speed  v .


A French cyclotron, produced in  Zürich , Switzerland in 1937. The vacuum chamber containing the dees  (at left)  has been removed from the magnet  (red, at right) .


A modern cyclotron used for  radiation therapy . The magnet is painted yellow.


M. Stanley Livingston and  Ernest O. Lawrence   (right)  in front of Lawrence's 69 cm (27 in) cyclotron at the Lawrence Radiation Laboratory. The curving metal frame is the magnet's core, the large cylindrical boxes contain the coils of wire that generate the magnetic field. The vacuum chamber containing the "dee" electrodes is in the center between the magnet's poles.


X-ray machine


Naturally occurring electron-positron annihilation as a result of beta plus decay


Electron/positron annihilation at various energies


An example of lung scintigraphy examination


Coded aperture  mask for gamma camera (for  SPECT )


Gamma camera


Diagrammatic cross section of a gamma camera detector


Details of the cross section of a gamma camera


Different assumptions on the extrapolation of the cancer risk vs. radiation dose to low-dose levels, given a known risk at a high dose: (A)  supra-linearity,  (B)  linear (C)  linear-quadratic,  (D)  hormesis


Increased Risk of Solid Cancer with Dose for  A-bomb survivors , from BEIR report. Notably, this exposure pathway occurred from essentially a massive spike or pulse of radiation, a result of the brief instant that the bomb exploded, which while somewhat similar to the environment of a  CT scan , is wholly unlike the low  dose rate  of living in a contaminated area such as  Chernobyl , where the  dose rate  is orders of magnitude smaller. LNT does not consider dose rate and is an unsubstantiated  one size fits all  approach based solely on total  absorbed dose . When the two environments and cell effects are vastly different. Likewise, it has also been pointed out that bomb survivors inhaled carcinogenic  benzopyrene  from the burning cities, yet this is not factored in. [ 7 ]


Plain X-ray of the wrist and hand


One frame of an MRI scan of the head showing the eyes and brain


Ultrasound image showing the liver, gallbladder and common bile duct.


Basic principle of  tomography : superposition free tomographic cross sections S 1  and S 2  compared with the (not tomographic) projected image P


CT scanning  ( volume rendered  in this case) confers a  radiation dose  to the developing fetus.


In a derivative of a medical image created in the U.S., added annotations and explanations may be copyrightable, but the medical image itself remains public domain.


Pharmaceutical drug which emits radiation, used as a diagnostic or therapeutic agent


A fully automated  radiosynthesis  interface of PET-radiotracers


Schematic representation of a two-step pretargeting approach.


SPECT / CT  images of injected gold-coated  lanthanum / gadolinium  phosphate nanoparticles containing the  alpha-emitting  radionuclide  actinium-225  in a mouse.  Depending on the surface functionalization, the particles migrate either to the lungs or the liver. [ 1 ]


A  fume hood  is an  engineering control  typically used to protect workers using nanoparticles.


Comparison of range of α (red) and β− (white) particles


Linear accelerator


Animation of the operation of a medical use linear accelerator


Turntable rotation


Simulated Therac-25 user interface


DEC  VT100  video  computer terminal


Diagram of a well counter


The facade of the ESR as seen from the  Maria am Gestade  church.


Entrance hall of ECR 2023


Using early  Crookes tube  X-Ray apparatus in 1896. One man is viewing his hand with a  fluoroscope  to optimise tube emissions, the other has his head close to the tube. No precautions  are being taken.


Monument to the X-ray and Radium Martyrs of All Nations  erected 1936 at St. Georg hospital in Hamburg, commemorating 359 early radiology workers.


External dose quantities used in radiation protection and dosimetry based on ICRU 57, jointly developed with the ICRP


The ICR discusses all forms of ionising radiation


Typical X-ray equipment in the 1940s


STUK's headquarters in Jokiniemi,  Vantaa


Radiation Therapy Oncology Group


Radiological Society of North America (RSNA)


RSNA 2021 AI Showcase at McCormick Place in Chicago


RWB logo


An example of a SoR banner in a  trade union  demonstration  (2011)


The Svedberg Laboratory in October 2016


The Gustaf Werner Cyclotron at The Svedberg Laboratory, Uppsala University, Uppsala, Sweden.


The Research Imaging Institute


A radiologist interpreting  magnetic resonance imaging


Radiography of the knee using a DR machine


Projectional radiograph  of the knee


Image from a  CT scan  of the brain


MRI of the knee


A radiologist interprets medical images on a modern  picture archiving and communication system  (PACS) workstation. San Diego, California, 2010.


X-ray  of a hand with calculation of  bone age  analysis


Radiation sickness


Harry K. Daghlian 's hand 9 days after he had manually stopped a  prompt critical  fission reaction during an accident with what later obtained the nickname the  demon core . He received a dose of 5.1  Sv , [ 18 ]  or 3.1  Gy . [ 19 ]  He died 16 days after this photo was taken.


Both dose and dose rate contribute to the severity of acute radiation syndrome. The effects of  dose fractionation  or rest periods before repeated exposure also shift the  LD50  dose upwards.


Comparison of Radiation Doses – includes the amount detected on the trip from Earth to Mars by the  RAD  on the  MSL  (2011–2013). [ 22 ] [ 23 ] [ 24 ] [ 25 ]