By the early 1950s, several professional organizations issued warnings against the continued use of shoe-mounted fluoroscopes, including the American Conference of Governmental Industrial Hygienists, the American College of Surgeons, the New York Academy of Medicine, and the American College of Radiology. At the same time, the  District of Columbia  enacted regulations requiring that shoe-mounted fluoroscopes be operated only by a licensed physical therapist. A few years later, the state of  Massachusetts  passed regulations stating that these machines could only be operated by a licensed physician. In 1957, the use of shoe-mounted fluoroscopes was banned by court order in  Pennsylvania . By 1960, these measures and pressure from insurance companies led to the disappearance of the shoe-mounted fluoroscope, at least in the United States. [ 26 ]


In Switzerland, there were 1,500 shoe-mounted fluoroscopes in use, 850 were required to be inspected by the  Swiss Electrotechnical Association  by a decree of the  Federal Department of Home Affairs  on October 7, 1963. The last one was decommissioned in 1990. [ 27 ]


In Germany, the machines were not banned until 1976.   The fluoroscopy machine emitted uncontrolled X-rays, which continuously exposed children, parents, and sales staff. The all-wood cabinet of the machine did not prevent the X-rays from passing through, resulting in particularly high cumulative radiation levels for the cashier when the pedoscope was placed near the cash register. The all-wood cabinet of the machine did not prevent the X-rays from passing through, resulting in particularly high cumulative radiation levels for the cashier when the pedoscope was placed near the cash register. It is clear that the machine was not designed with proper safety measures in place, leading to dangerous levels of radiation exposure. The well-established long-term effects of X-rays, including genetic damage and carcinogenicity, suggest that the use of pedoscopes worldwide over several decades may have contributed to health effects.The well-established long-term effects of X-rays, including genetic damage and carcinogenicity, suggest that the use of pedoscopes worldwide over several decades may have contributed to health effects. However, it cannot be definitively proven that they were the sole cause. [ 28 ] [ 29 ]  For example, a direct link has been discussed in the case of basal cell carcinoma of the foot. [ 30 ]  In 1950, a case was published in which a shoe model had to have a leg amputated as a result. [ 31 ]


In 1896, Viennese dermatologist  Leopold Freund  (1868-1943) used X-rays to treat patients for the first time. He successfully irradiated the  hairy nevus  of a young girl. In 1897, Hermann Gocht (1869–1931) published the treatment of  trigeminal neuralgia  with X-rays, and  Alexei Petrovich Sokolov  (1854-1928) wrote about radiotherapy for  arthritis  in the oldest radiology journal, Advances in the field of X-rays ( RöFo ). In 1922, X-rays were recommended as safe for many diseases and for diagnostic purposes. Radiation protection was limited to recommending doses that would not cause  erythema  (reddening of the skin). For example, X-rays were promoted as an alternative to  tonsillectomy . It was also boasted that in 80% of cases of  diphtheria  carriers,  Corynebacterium diphtheriae  was no longer detectable within two to four days. [ 32 ]  In the 1930s,   Günther von Pannewitz  (1900–1966), a radiologist from Freiburg, Germany, perfected what he called  X-ray stimulation radiation  for degenerative diseases. Low-dose radiation reduces the inflammatory response of tissues. Until about 1960, children with diseases such as  ankylosing spondylitis  or  favus  (head fungus) were irradiated, which was effective but led to increased cancer rates among patients decades later. [ 33 ] [ 34 ]  In 1926, the American pathologist  James Ewing  (1866-1943) was the first to observe bone changes as a result of radiotherapy, [ 35 ]  which he described as  radiation osteitis ( now  Osteoradionecrosis ). [ 36 ]  In 1983, Robert E. Marx stated that osteoradionecrosis is radiation-induced aseptic bone necrosis. [ 37 ] [ 38 ]  The acute and chronic inflammatory processes of osteoradionecrosis are prevented by the administration of steroidal anti-inflammatory drugs. In addition, the administration of  pentoxifylline  and antioxidant treatments, such as  superoxide dismutase  and  tocopherol  (vitamin E) are recommended. [ 39 ]


Sonography  (ultrasound diagnostics) is a versatile and widely used imaging modality in medical diagnostics.  Ultrasound  is also used in  therapy . However, it uses  mechanical waves  and no ionizing or non-ionizing radiation. Patient safety is ensured if the recommended limits for avoiding  cavitation  and overheating are observed, see also  Safety Aspects of Sonography .


Even devices that use alternating  magnetic fields  in the  radiofrequency range , such as  magnetic resonance imaging  (MRI), do not use ionizing radiation. MRI was developed as an imaging technique in 1973 by  Paul Christian Lauterbur  (1929-2007) with significant contributions from Sir  Peter Mansfield  (1933-2017). [ 40 ]  Jewelry or piercings can become very hot; on the other hand, a high tensile force is exerted on the jewelry, which in the worst case can cause it to be torn out. To avoid pain and injury, jewelry containing  ferromagnetic  metals should be removed beforehand.  Pacemakers ,  defibrillator  systems, and large  tattoos  in the examination area that contain metallic  color pigments  may heat up or cause second-degree burns or malfunction of the implants. [ 41 ] [ 42 ]


Photoacoustic Tomography  (PAT) is a hybrid imaging modality that utilizes the photoacoustic effect without the use of ionizing radiation. It works without contact with very fast laser pulses that generate ultrasound in the tissue under examination. The local absorption of the light leads to sudden local heating and the resulting thermal expansion. The result is broadband acoustic waves. The original distribution of absorbed energy can be reconstructed by measuring the outgoing ultrasound waves with appropriate ultrasound transducers.


In order to better assess radiation protection, the number of X-ray examinations, including the dose, has been recorded annually in Germany since 2007. However, the  Federal Statistical Office  does not have complete data for conventional X-ray examinations. In 2014, the total number of X-ray examinations in Germany was estimated to be about 135 million, of which about 55 million were dental X-ray examinations. The average effective dose from x-ray examinations per inhabitant in Germany in 2014 was about 1.55 mSv (about 1.7 x-ray examinations per inhabitant per year). The proportion of dental X-rays is 41%, but accounts for only 0.4% of the collective effective dose. [ 43 ]


In Germany, Section 28 of the X-ray Ordinance (RöV) has required since 2002 that the attending physician must have an X-ray pass available for X-ray examinations and offer it to the patient. The pass contains information about the patient's X-rays to avoid unnecessary examinations and to allow comparison with previous images. With the entry into force of the new Radiation Protection Ordinance on December 31, 2018, this obligation no longer applies. In Austria and Switzerland, x-ray passports have so far been available voluntarily. [ 44 ] [ 45 ]  In principle, there must always be both a justifiable indication for the use of X-rays and the informed consent of the patient. In the context of medical treatment, informed consent refers to the patient's agreement to all types of interventions and other medical measures.


§ 630d
Act of (in German)


Over the years, there have been increasing efforts to reduce radiation exposure to therapists and patients.


Following Rollins' discovery in 1920 that lead aprons protected against X-rays, lead aprons with a lead thickness of 0.5 mm were introduced. Due to their weight, lead-free and lead-reduced aprons were subsequently developed. In 2005, it was recognized that in some cases the protection was significantly less than wearing lead aprons. [ 46 ]  The lead-free aprons contain  tin ,  antimony  and  barium , which have the property of producing intense radiation ( X-ray fluorescence  radiation) when irradiated. In Germany, the Radiology Standards Committee has taken up the issue and introduced a German standard (DIN 6857-1) in 2009. The international standard IEC 61331-3:2014 was finally published in 2014. Protective aprons that do not comply with DIN 6857-1 of 2009 or the new IEC 61331-1 [ 47 ]  of 2014 may result in higher exposures. There are two classes of lead equivalency classes: 0.25 mm and 0.35 mm. The manufacturer must specify the area weight in kg/m 2  at which the protective effect of a pure lead apron of 0.25 or 0.35 mm Pb is achieved. The protective effect of an apron shall be appropriate to the energy range used, up to 110 kV for low energy aprons and up to 150 kV for high energy aprons. [ 48 ]


If necessary, lead glass panels must also be used, with the front panels having a lead equivalent of 0.5-1.0 mm, depending on the application, and the side shields having a lead equivalent of 0.5-0.75 mm.


Outside the useful beam, radiation exposure is primarily caused by scattered radiation from the tissue being scanned. During examinations of the head and torso, this scattered radiation can spread throughout the body and is difficult to shield with radiation protective clothing. Fears that a lead apron will prevent radiation from leaving the body are unfounded, however, because lead absorbs radiation rather than scattering it. [ 49 ]


When preparing an  orthopantomogram  (OPG) for a dental overview radiograph, it is sometimes recommended not to wear a lead apron, as it does little to shield scattered radiation from the jaw area, but may hinder the rotation of the imaging device. [ 50 ]  However, according to the 2018 X-ray regulation, it is still mandatory to wear a lead apron when taking an OPG.


In the same year as the discovery of X-rays,  Mihajlo Idvorski Pupin  (1858-1935) invented the method of placing a sheet of paper coated with  fluorescent  substances on the  photographic plate , drastically reducing the exposure time and thus the radiation exposure. 95% of the film was blackened by the intensifying film and only the remaining 5% was directly blackened by the X-rays. Thomas Alva Edison identified the blue-emitting  calcium tungstate  (CaWO4) as a suitable phosphor, which quickly became the standard for X-ray intensifying film. In the 1970s, calcium tungstate was replaced by even better and finer intensifying films with rare  earth-based phosphors  ( terbium -activated  lanthanum oxybromide ,  gadolinium oxysulfide ). [ 51 ]  The use of intensifying films in dental film production did not become widespread because of the loss of image quality. [ 52 ]  The combination with  high-sensitivity films  further reduced radiation exposure.


An  anti-scatter grid  is a device in X-ray technology that is placed in front of the image receiver ( screen ,  detector , or film) and reduces the incidence of diffuse radiation on it. The first diffusion radiation grid was developed in 1913 by  Gustav Peter Bucky  (1880-1963). The US radiologist Hollis Elmer Potter (1880-1964) improved it in 1917 by adding a moving device. [ 53 ]  The radiation dose must be increased when using scattered radiation grids. For this reason, the use of scattered radiation equipment should not be used on children. In digital radiography, a grid may be omitted under certain conditions to reduce radiation exposure to the patient. [ 54 ]


Radiation protection measures may also be necessary against scattered radiation, which occurs during tumor irradiation of the head and neck on metal parts of the dentition ( dental fillings ,  bridges , etc.). Since the 1990s, soft tissue retractors known as  radiation protection splints  have been used to prevent or reduce  mucositis , an inflammation of the mucous membranes. It is the most significant adverse acute side effect of radiation. [ 55 ]  The radiation protection splint is a spacer that keeps the mucosa away from the teeth and reduces the amount of scattered radiation that hits the mucosa according to the square law of distance. Mucositis, which is extremely painful, is one of the most significant detriments to a patient's quality of life and often limits radiation therapy, thereby reducing the chances of tumor cure. [ 56 ]  The splint reduces oral mucosal reactions that typically occur in the second and third third of a radiation series and are irreversible.


The Japanese  Hisatugu Numata  developed the first panoramic radiograph in 1933/34. This was followed by the development of intraoral panoramic X-ray units, in which the X-ray tube is placed intraorally (inside the mouth) and the  X-ray film  extraorally (outside the mouth). At the same time, Horst Beger from Dresden in 1943 and the Swiss dentist Walter Ott in 1946 worked on the Panoramix (Koch & Sterzel), Status X ( Siemens ) and Oralix ( Philips ). [ 57 ]  Intraoral panoramic devices were discontinued at the end of the 1980s because the radiation exposure was too high in direct contact with the tongue and  oral mucosa  due to the intraoral tube.


Eastman Kodak  filed the first patent for  digital radiography  in 1973. [ 58 ]  The first commercial CR (Computed Radiology) solution was offered by  Fujifilm  in Japan in 1983 under the device name CR-101. [ 59 ]  X-ray imaging plates are used in X-ray diagnostics to record the shadow image of X-rays. The first commercial digital X-ray system for use in dentistry was introduced in 1986 by  Trophy Radiology  (France) under the name Radiovisiography. [ 60 ]  Digital x-ray systems help reduce radiation exposure. Instead of film, the machines contain a  scintillator  that converts the incident X-ray photons either into visible light or directly into electrical impulses.


In 1972, the first commercial  CT  scanner for clinical use went into operation at Atkinsons Morley Hospital in London. Its inventor was the English engineer  Godfrey Newbold Hounsfield  (1919-2004), who shared the 1979  Nobel Prize in Medicine  with  Allan McLeod Cormack  (1924-1998) for his pioneering work in the field of computed tomography. The first steps toward dose reduction were taken in 1989 in the era of single-slice spiral CT. The introduction of multi-slice spiral computed tomography in 1998 and its continuous development made it possible to reduce the dose by means of dose modulation. The tube current is adjusted, for example by reducing the power for images of the lungs compared to the  abdomen . The tube current is modulated during rotation. Because the human body has an approximately oval cross-section, radiation intensity is reduced when radiation is delivered from the front or back, and is increased when radiation is delivered from the side. This dose control also depends on the  body mass index . For example, the use of dose modulation in the head and neck region reduces total exposure and organ doses to the  thyroid  and  eye lens  by up to 50% without significantly compromising diagnostic image quality. [ 61 ]  The  Computed Tomography Dose Index  (CTDI) is used to measure radiation exposure during a CT scan. The CTDI was first defined by the  Food and Drug Administration  (FDA) in 1981. The unit of measurement for the CTDI is the mGy (milli- Gray ). Multiplying the CTDI by the length of the examination volume yields the dose-length product (DLP), which quantifies the total radiation exposure to the patient during a CT scan. [ 62 ]


An X-ray room must be shielded on all sides with 1 mm lead equivalent shielding.  Calcium silicate  or solid brick  masonry  is recommended. A steel  jamb  should be used, not only because of the weight of the heavy shielding door but also because of the shielding; wooden frames must be shielded separately. The shielding door must be covered with a 1 mm thick lead foil and a  lead glass  window must be installed as a visual connection. A keyhole shall be avoided. All installations (sanitary or electrical), that interrupt the radiation protection, must be leaded (


§ 20
 § 20 Röntgenverordnung  (röv_1987)  [§ 20 X-ray Ordinance]  (in German)
and


§ Annex+2
 Annex 2 (to § 8 para. 1 sentence 1 RöV)  (röv_1987) (in German)
Depending on the application,  nuclear medicine  requires even more extensive protective measures, up to and including concrete walls several meters thick. [ 63 ]  In addition, from December 31, 2018, when the latest amendments to Section 14 (1) No. 2b of the Radiation Protection Act


§ 14
 Strahlenschutzgesetz – StrlSchG   [Radiation Protection Act (StrlSchG)]  (in German)


come into force, an  expert in medical physics  for X-ray diagnostics and therapy must be consulted for the optimization and quality assurance of the application and for advice on radiation protection issues.


Each facility operating an x-ray unit shall have sufficient personnel with appropriate expertise. The person responsible for radiation protection or one or more  Radiation Safety Officers  shall have appropriate qualifications, which shall be regularly updated. X-ray examinations may be technically performed by any other staff member of a medical or dental practice if they are under the direct supervision and responsibility of the person responsible and if they have knowledge of radiation protection.


This knowledge of radiation protection has been required since the amendment of the X-ray Ordinance in 1987; medical and  dental assistants  (then called medical assistants or dental assistants) received this additional training in 1990. [ 64 ]  The regulations for the specialty of radiology were tightened by the Radiation Protection Act, which came into force on October 1, 2017. [ 65 ]


The handling of radioactive substances and ionizing radiation (if not covered by the X-ray Ordinance) is regulated by the Radiation Protection Ordinance ( StrlSchV ). Section 30 StrlSchV


§ 30
 StrlSchV  (in German)
defines the "Required expertise and knowledge in radiation protection".


The  Association of German Radiation Protection Physicians  ( VDSÄ ) was formed in the late 1950s from a  working group of radiation protection physicians of the German Red Cross  and was founded in 1964. It was dedicated to the promotion of radiation protection and the representation of medical, dental, and veterinary radiation protection concerns to the public and the health care system. In 2017, it was merged into the Professional Association for Radiation Protection. The  Austrian Association for Radiation Protection  ( ÖVS ), [ 66 ]  founded in 1966, pursues the same goals as the Association for Medical Radiation Protection in Austria. [ 67 ]  The  Professional Association for Radiation Protection  for Germany and Switzerland is networked worldwide. [ 68 ]


In radiotherapy, radiation protection is often overlooked in favor of structural safeguards and therapist protection. The benefit/risk assessment should prioritize both the therapeutic goal of treating the patient's cancer and the safety of all involved. However, it is crucial to ensure that radiation is delivered only where it is needed through appropriate treatment planning. By employing strong radiation protection measures, we can confidently provide effective treatment while minimizing potential risks. Linear accelerators replaced cobalt and caesium emitters in routine therapy due to their superior technical characteristics and risk profile. They have been available since about 1970. The presence of a medical physicist responsible for technical quality control is required for linear accelerators, unlike X-rays and telecurie systems. It is important to note that radiation necrosis is the necrosis of cells in an organism caused by the effects of ionizing radiation. Radionecrosis is a serious complication of radiosurgical treatment that becomes clinically apparent months or years after irradiation. [ 69 ]  Radiation therapy has significantly reduced the incidence of radionecrosis since its early days. Modern radiation techniques prioritize the sparing of healthy tissue while irradiating as much of the area around the tumor as possible to prevent recurrence. It is important to note that patients undergoing radiotherapy face a certain level of radiation risk.


While there is limited literature on radiation injury to animals, there is no evidence of other types of radiation injury. Diagnostic radiation has been shown to cause local burns in animals, typically resulting from prolonged exposure of body parts or sparks from old x-ray tubes. It is important to note that the frequency of injury to veterinary staff and veterinarians is significantly lower than that in human medicine, highlighting the safety of diagnostic radiation in veterinary practice. In veterinary medicine, fewer images are taken compared to human medicine, particularly fewer CT scans. However, due to the manual restraint of animals to avoid anesthesia, at least one person is present in the control area, resulting in significantly higher radiation exposure than that of human medical staff. It is important to note that since the 1970s, dosimeters have been used to measure the radiation exposure of veterinary personnel, ensuring their safety.


Feline hyperthyroidism  (overactive thyroid) is a common disease in older cats.  Radioiodine  therapy is considered by many authors to be the treatment of choice. Following the administration of radioactive iodine, cats are kept in an isolation pen. The cat's radioactivity is measured to determine the time of discharge, which is typically 14 days after the start of therapy. The therapy requires significant radiation protection measures and is currently only offered at two veterinary facilities in Germany (as of 2010). After the start of treatment, cats must be kept indoors for four weeks, and contact with pregnant women and children under the age of 16 must be avoided due to residual radioactivity. [ 70 ]


Just like a medical practice, any veterinary practice operating an X-ray machine must have sufficient staff with the appropriate expertise, as required by Section 18 of the X-Ray Ordinance 2002. The corresponding training for  paraveterinary workers  (then called veterinary nurses) took place in 1990. [ 64 ]


In 2017,  Linsengericht  (Hesse) opened Europe's first clinic for horses with cancer. Radiation therapy is administered in a treatment room that is eight meters wide, on a specially designed table that can withstand heavyweight. The surrounding area is protected from radiation by three-meter thick walls. Mobile equipment is used to irradiate tumors in small animals at various locations. [ 71 ]


Radon is a naturally occurring radioactive  noble gas  discovered in 1900 by  Friedrich Ernst Dorn  (1848-1916) and is considered  carcinogenic . Radon is increasingly found in areas with high levels of  uranium  and  thorium  in the soil. These are mainly areas with high  granitic rock deposits . According to studies by the  World Health Organization , the incidence of  lung cancer  increases significantly at radiation levels of 100-200  Bq  per cubic meter of indoor air. The likelihood of developing lung cancer increases by 10% with each additional 100 Bq/m 3  of indoor air. [ 72 ]


Elevated radon levels have been measured in numerous areas in Germany, particularly in southern Germany, Austria and Switzerland.


The Federal Office for Radiation Protection has developed a radon map of Germany. [ 73 ]  The EU Directive 2013/59/Euratom (Radiation Protection Basic Standards Directive) introduced  reference levels  and the possibility for workers to have their workplace tested for radon exposure. In Germany, it was implemented in the Radiation Protection Act (Chapter 2 or Sections 124-132 StrlSchG)


§ 124-132
 StrlSchG  (in German)
and the amended Radiation Protection Ordinance (Part 4 Chapter 1, Sections 153-158 StrlSchV).


§ 153-158
Act of (in German)
The new radon protection regulations for workplaces and new residential buildings have been binding since January 2019. Extensive radon contamination and radon precautionary areas have been determined by the ministries of the environment of the federal states (as of June 15, 2021). [ 74 ]


The highest radon concentrations in Austria were measured in 1991 in the municipality of Umhausen in Tyrol. Umhausen has about 2300 inhabitants and is located in the Ötztal valley. Some of the houses there were built on a bedrock of  granite gneiss . From this porous  subsoil , the radon present in the rock seeped freely into the unsealed cellars, which were contaminated with up to 60,000 Becquerels of radon per cubic meter of air. [ 75 ]  Radon levels in the apartments in Umhausen have been systematically monitored since 1992. Since then, extensive radon mitigation measures have been implemented in the buildings: New buildings, sealing of cellar floors, forced ventilation of cellars or relocation. Queries in the  Austrian Health Information System  ( ÖGIS ) have shown that the incidence of new cases of lung cancer has declined sharply since then. The Austrian National Radon Project (ÖNRAP) has studied radon exposure throughout the country. [ 76 ]  Austria also has a Radiation Protection Act as a legal basis. [ 77 ]  Indoor limits were set in 2008  [ 78 ]  The Austrian Ministry of the Environment states that


"Precautionary measures in radiation protection use the generally accepted model that the risk of lung cancer increases uniformly (linearly) with radon concentration. This means that an increased risk of lung cancer does not only occur above a certain value, but that a guideline or limit value only adjusts the magnitude of the risk in a meaningful way to other existing risks. Achieving a guideline or limit therefore means taking a risk that is still (socially) acceptable. It therefore makes perfect sense to take simple measures to reduce radon levels, even if they are below the guideline values."


In Austria, the Radon Protection Ordinance in its version of September 10, 2021 is currently in force, which also defines the radon protection areas and radon precautionary areas. [ 79 ]


The aim of the Radon Action Plan 2012-2020 in Switzerland was to incorporate the new international recommendations into the Swiss strategy for protection against radon and thus reduce the number of lung cancer cases attributable to radon in buildings. [ 80 ]


On 1 January 2018, the limit value of 1000 Bq/m 3  was replaced by a reference value of 300 becquerels per cubic meter (Bq/m 3 ) for the radon gas concentration averaged over a year in "rooms in which people regularly spend several hours a day".


Subsequently, on May 11, 2020, the  Federal Office of Public Health  FOPH issued the Radon Action Plan 2021-2030. [ 81 ]  The provisions on radon protection are primarily laid down in the Radiation Protection Ordinance (RPO). [ 82 ]


In 1879,  Walther Hesse  (1846-1911) and  Friedrich Hugo Härting  published the study "Lung Cancer, the Miners' Disease in the Schneeberg Mines". Hesse, a  pathologist , was shocked by the poor health and young age of the miners. [ 83 ]  This particular form of  bronchial carcinoma  was given the name  Schneeberg  disease  because it occurred among miners in the  Schneeberg  mines (Saxon Erz Mountains).


When Hesse's report was published, radioactive radiation and the existence of radon were unknown. It was not until 1898 that  Marie Curie-Skłodowska  (1867-1934) and her husband  Pierre Curie  (1859-1906) discovered radium and created the concept of  radioactivity . [ 84 ]  Beginning in the fall of 1898, Marie Curie suffered from inflammation of the fingertips, the first known symptoms of  radiation sickness .


In the  Jáchymov  mines, where silver and  non-ferrous metals  were mined from the 16th to the 19th century,  uranium  ore was mined in abundance in the 20th century. It was only during the  Second World War  that restrictions were imposed on ore mining in the Schneeberg and Jáchymov mines. After World War II,  uranium mining  was accelerated for the  Soviet atomic bomb project  and the emerging Soviet  nuclear industry.  Forced labor was used. Initially, these were German prisoners of war and displaced persons, and after the  February Revolution of 1948 , political prisoners were imprisoned by the  Communist Party regime in Czechoslovakia , as well as conscripted civilian workers. [ 85 ]  Several "Czechoslovak  gulags " were established in the area to house these workers. In all, about 100,000 political prisoners and more than 250,000 forced laborers passed through the camps. About half of them probably did not survive the mining work. [ 86 ]  Uranium mining ceased in 1964. We can only speculate about other victims who died as a result of radiation. Radon-bearing springs discovered during the mining in the early 20th century established a spa industry that is still important today, as well as the town's status as the oldest radium brine spa in the world.


The approximately 200,000 uranium miners employed by  Wismut AG  in the former Soviet occupation zone of East Germany were exposed to very high levels of radiation, particularly between 1946 and 1955, but also in later years. This exposure was caused by the inhalation of radon and its radioactive by-products, which were deposited to a considerable extent in the inhaled dust. Radiation exposure was expressed in the historical unit of  working level month  (WLM). This unit of measurement was introduced in the 1950s specifically for occupational safety in  uranium mines  in the U.S. [ 87 ]  to record radiation exposure resulting from radioactive exposure to radon and its decay products in the air we breathe. [ 88 ]  Approximately 9000 workers at Wismut AG have been diagnosed with lung cancer.


Until the 1930s, radium compounds were not only considered relatively harmless, but also beneficial to health, and were advertised as medicines for a variety of ailments or used in products that glowed in the dark. Processing took place without any safeguards.


Until the 1960s, radioactivity was often handled naively and carelessly. From 1940 to 1945, the Berlin-based  Auergesellschaft , founded by  Carl Auer von Welsbach  (1858-1929,  Osram ), produced a  radioactive  toothpaste called  Doramad  that contained  thorium-X  and was sold internationally. It was advertised with the statement, "Its radioactive radiation strengthens the defenses of the teeth and gums. The  cells  are charged with new life energy and the destructive effect of  bacteria  is inhibited. This gave the claim of  radiant white teeth  a double meaning. By 1930, there were also bath additives and  eczema  ointments under the brand name "Thorium-X". Radium was also added to toothpastes, such as  Kolynos toothpaste . After World War I, radioactivity became a symbol of modern achievement and was considered "chic". Radioactive substances were added to mineral water, condoms, and cosmetic powders. Even chocolate laced with radium was sold. [ 89 ]  The toy manufacturer  Märklin  in the Swabian town of Göppingen tested the sale of an X-ray machine for children. [ 90 ]  At upper-class parties, people "photographed" each other's bones for fun. A system called  Trycho  ( Ancient Greek :  τριχο- ,  romanized :  tricho- ,  lit.   'concerning the hair') for  epilation  (hair removal) of the face and body was  franchised  in the USA. As a result, thousands of women suffered skin burns,  ulcers  and tumors. [ 25 ]  It was not until the  atomic bombings of Hiroshima and Nagasaki  that the public became aware of the dangers of  ionizing radiation  and these products were banned. [ 91 ] [ 92 ] [ 93 ]


A radium industry developed, using radium in creams, beverages, chocolates, toothpastes, and soaps. [ 94 ] [ 95 ]  It took a relatively long time for radium and its decay product radon to be recognized as the cause of the observed effects.  Radithor , a radioactive agent consisting of triple- distilled water  in which the radium  isotopes   226 Ra and  228 Ra were dissolved so that it had an  activity  of at least one  microcurie , was marketed in the United States. [ 96 ]  It was not until 1932, when the prominent American athlete  Eben Byers , who by his own account had taken about 1,400 vials of Radithor as medicine on the recommendation of his physician, fell seriously ill with cancer, lost many of his teeth, and died shortly thereafter in great agony, that strong doubts were raised about the healing powers of Radithor and radium water. [ 97 ]


1908 saw a boom in the use of radioactive water for therapeutic purposes. The discovery of springs in Oberschlema and  Bad Brambach  paved the way for the establishment of radium spas, which relied on the healing properties of radium. During the cures, people bathed in radium water, drank cures with radium water, and inhaled radon in emanatoriums. The baths were visited by tens of thousands of people every year, hoping for  hormesis .


To this day, therapeutic applications are carried out in spas and healing tunnels. The natural release of radon from the ground is used. According to the German Spa Association, the activity in water must be at least 666 Bq/liter. The requirement for inhalation treatments is at least 37,000 Bq/m 3  of air. This form of therapy is not scientifically accepted and the potential risk of radiation exposure is criticized. The equivalent dose of a radon cure in Germany is given by the individual health resorts as about one to two millisieverts, depending on the location. In 2010, doctors in Erlangen, using the (outdated)  LNT (Linear, No-Threshold) model , concluded that five percent of all lung cancer deaths in Germany are caused by radon. [ 98 ]  There are radon baths in  Bad Gastein ,  Bad Hofgastein  and  Bad Zell  in Austria, in  Niška Banja  in Serbia, in the radon revitalization bath in  Menzenschwand  and in  Bad Brambach ,  Bad Münster  am  Stein-Ebernburg ,  Bad Schlema ,  Bad Steben ,  Bad Schmiedeberg  and  Sibyllenbad  in Germany, in  Jáchymov  in the Czech Republic, in  Hévíz  in Hungary, in  Świeradów-Zdrój  (Bad Flinsberg) in Poland, in Naretschen and  Kostenez  in Bulgaria and on the island of  Ischia  in Italy. There are radon tunnels in  Bad Kreuznach  and  Bad Gastein . [ 99 ]


The dangers of radium were recognized in the early 1920s and first described in 1924 by New York dentist and oral surgeon Theodor Blum (1883-1962). [ 100 ]  He was particularly aware of the use of radium in the watch industry, where it was used for luminous dials. He published an article on the clinical picture of the so-called  radium jaw . He observed this disease in female patients who, as dial painters, came into contact with luminous paint whose composition was similar to Radiomir, a luminous material invented in 1914 consisting of a mixture of  zinc sulfide  and  radium bromide . As they painted, they used their lips to form the tip of the phosphorus-laden brush into the desired pointed shape, and this is how the radioactive radium entered their bodies. In the U.S. and Canada alone, about 4,000 workers were affected over the years. [ 101 ]  In retrospect, the factory workers were called the  Radium Girls . They also played with the paint, painting their fingernails, teeth and faces. This made them glow at night to the surprise of their companions.


After  Harrison Stanford Martland  (1883-1954), chief medical examiner in  Essex County , detected the radioactive noble gas radon (a decay product of radium) in the breath of the Radium Girls, he turned to  Charles Norris  (1867-1935) and  Alexander Oscar Gettler  (1883-1968). In 1928, Gettler was able to detect a high concentration of radium in the bones of Amelia Maggia, one of the young women, even five years after her death. [ 102 ] [ 103 ]  In 1931, a method was developed for determining radium dosage using a film dosimeter. A standard preparation is irradiated through a hardwood cube onto an X-ray film, which is then blackened. For a long time, the  cube minute  was an important unit of radium dosage. [ 104 ]  It was calibrated by ionometric measurements. The radiologists  Hermann Georg Holthusen  (1886-1971) and  Anna Hamann  (1894-1969) found a calibration value of 0.045 r/min in 1932/1935. The calibration film receives the y-ray dose of 0.045 r per minute through the wooden cube from the preparation of 13.33 mg. In 1933, the physicist  Robley D. Evans  (1907-1995) made the first measurements of radon and radium in the excretions of female workers. [ 105 ]  On this basis, the National Bureau of Standards, the predecessor to the  National Institute of Standards and Technology  (NIST), set the limit for radium at 0.1  microcuries  (about 3.7  kilobecquerels ) in 1941.


A  Radium Action Plan 2015-2019  aims to solve the problem of radiological contamination in Switzerland, mainly in the  Jura Mountains , due to the use of radium luminous paint in the watch industry until the 1960s. [ 106 ]


In France, a line of cosmetics called  Tho-Radia , which contained both thorium and radium, was created in 1932 and lasted until the 1960s. [ 107 ]


Terrestrial radiation  is the ubiquitous radiation on Earth caused by  radionuclides  in the ground that were formed billions of years ago by stellar  nucleosynthesis  and have not yet decayed due to their long  half-lives . Terrestrial radiation is caused by natural radionuclides that occur naturally in the Earth's soil, rocks,  hydrosphere , and  atmosphere . Natural radionuclides can be divided into  cosmogenic  and  primordial nuclides . Cosmogenic nuclides do not contribute significantly to the terrestrial ambient radiation at the Earth's surface. The sources of terrestrial radiation are the natural radioactive nuclides found in the uppermost layers of the Earth, in the water and in the air. These include in particular [ 108 ]


According to the  World Nuclear Association ,  coal  from all deposits contains traces of various radioactive substances, particularly radon, uranium and thorium. These substances are released during coal mining, especially from surface mines, through power plant emissions, or power plant ash, and contribute to terrestrial radiation exposure through their exposure pathways. [ 109 ]


In December 2009, it was revealed that  oil  and  gas production  generates millions of tons of radioactive waste each year, much of which is improperly disposed of without detection, including  226 Radium  and  210 Polonium . [ 110 ] [ 111 ]  The specific activity of the waste ranges from 0.1 to 15,000 becquerels per gram. In Germany, according to the  Radiation Protection Ordinance  of 2001, the material is subject to monitoring at one Becquerel per gram and would have to be disposed of separately. The implementation of this regulation has been left to the industry, which has disposed of the waste carelessly and improperly for decades.


Every building material contains traces of natural radioactive substances, especially  238 uranium,  232 thorium, and their decay products, and  40 potassium. Solidified and effusive rocks such as  granite ,  tuff , and  pumice  have higher levels of radioactivity. In contrast, sand,  gravel ,  limestone , and natural  gypsum  ( calcium sulfate  dihydrate) have low levels of radioactivity. The European Union's  Activity Concentration Index  (ACI), developed in 1999, can be used to assess radiation exposure from building materials. [ 112 ]  It replaces the Leningrad summation formula, which was used in 1971 in Leningrad (St. Petersburg) to determine how much radiation exposure from building materials is permissible for humans. The ACI is calculated from the sum of the weighted activities of  40 potassium,  226 radium, and  232 thorium. The  weighting  takes into account the relative harmfulness to humans. According to official recommendations, building materials with a European ACI value greater than "1" should not be used in large quantities. [ 113 ]


Uranium  pigments  are used to color ceramic tiles with  uranium glazes  (red, yellow, brown), where 2 mg of uranium per cm 2  is allowed. Between 1900 and 1943, large quantities of uranium-containing ceramics were produced in the United States, as well as in Germany and Austria. It is estimated that between 1924 and 1943, 50-150  tons  of  uranium (V,VI) oxide  were used annually in the U.S. to produce uranium-containing glazes. In 1943, the U.S. government imposed a ban on the civilian use of uranium-containing substances, which remained in effect until 1958. Beginning in 1958, the U.S. government, and in 1969 the  United States Atomic Energy Commission , sold depleted uranium in the form of  uranium(VI) fluoride  for civilian use. [ 114 ]  In Germany, uranium-glazed ceramics were produced by the  Rosenthal  porcelain factory and were commercially available until the early 1980s. [ 115 ]  Uranium-glazed ceramics should only be used as collector's items and not for everyday use due to possible abrasion.


The Federal Office for Radiation Protection's monitoring network measures natural radiation exposure through the local dose rate (ODL), expressed in microsieverts per hour (μSv/h).  In Germany, the natural ODL ranges from approximately 0.05 to 0.18 μSv/h, depending on local conditions. The ODL monitoring network has been operational since 1973 and currently comprises 1800 fixed, automatically operating measuring points. Its primary function is to provide early warning for the rapid detection of increased radiation from radioactive substances in the air in Germany. Spectroscopic probes have been successfully utilized since 2008 to determine the contribution of artificial radionuclides in addition to the local dose rate, showcasing the network's advanced capabilities. [ 116 ]  In addition to the ODL monitoring network of the Federal Office for Radiation Protection, there are other federal monitoring networks at the  Federal Maritime and Hydrographic Agency  and the  Federal Institute of Hydrology , which measure gamma radiation in water; the  German Meteorological Service  measures air activity with aerosol samplers. [ 117 ]  To monitor  nuclear facilities , the relevant federal states operate their own ODL monitoring networks. The data from these monitoring networks are automatically fed into the  Integrated Measurement and Information System  (IMIS), where they are used to analyze the current situation.


Many countries operate their own ODL monitoring networks to protect the public. In Europe, these data are collected and published on the EURDEP platform of the  European Atomic Energy Community . The European monitoring networks are based on Articles 35 and 37 of the  Euratom Treaty . [ 118 ]


Nuclear medicine  is the use of open radionuclides for diagnostic and therapeutic purposes ( radionuclide therapy ). [ 119 ]  It also includes the use of other radioactive substances and  nuclear physics  techniques for functional and localization diagnostics.  George de Hevesy  (1885-1966) lived as a lodger and in 1923 suspected that his landlady was offering him pudding that he had not eaten the following week. He mixed a small amount of a radioactive isotope into the leftovers. When she served him the pudding a week later, he was able to detect radioactivity in a sample of the casserole. When he showed this to his landlady, she immediately gave him notice. The method he used made him the  father of nuclear medicine . It became known as the  tracer method , which is still used today in nuclear medicine diagnostics. [ 120 ]  A small amount of a radioactive substance, its distribution in the organism, and its path through the human body can be tracked externally. This provides information about various  metabolic functions  of the body. The continuous development of radionuclides has improved radiation protection. For example, the mercury compounds  203 chloro-merodrin and  197 chloro-merodrin were abandoned in the 1960s as substances were developed that allowed a higher  photon  yield with less radiation exposure. Beta emitters such as  131 I and  90 Y are used in radionuclide therapy. In nuclear medicine diagnostics, the beta+ emitters  18 F,  11 C,  13 N, and  15 O are used as radioactive markers for tracers in  positron emission tomography  (PET). [ 121 ]   Radiopharmaceuticals  (isotope-labeled drugs) are being developed on an ongoing basis.


Radiopharmaceutical residues, such as empty application syringes and contaminated residues from the patient's toilet, shower and washing water, are collected in tanks and stored until they can be safely pumped into the sewer system. The storage time depends on the half-life and ranges from a few weeks to a few months, depending on the radionuclide. Since 2001, by


§ 29
 StrlSchV  (in German)
of the  Radiation Protection Ordinance , the specific radioactivity in the waste containers has been recorded in release  measuring stations  and the release time is calculated automatically. This requires measurements of the sample activity in Bq/g and the surface contamination in Bq/cm 2 . In addition, the behavior of the patients after their discharge from the clinic is prescribed. [ 122 ]  To protect personnel, syringe filling systems, borehole measurement stations for nuclide-specific measurement of low-activity, small volume individual samples, a lift system into the measurement chamber to reduce radiation exposure when handling highly active samples, probe measurement stations, ILP (isolated limb perfusion) measurement stations to monitor activity with one or more detectors during surgery and report leakage to the surgical  oncologist .


Radioiodine Therapy  (RIT) is a nuclear medicine procedure used to treat thyroid hyperfunction,  Graves' disease , thyroid enlargement, and certain forms of thyroid cancer. The radioactive  iodine isotope  used is  131 Iodine, a predominant  beta emitter  with a half-life of eight days, which is only stored in thyroid cells in the human body. In 1942,  Saul Hertz  (1905-1950) of the Massachusetts General Hospital and the physicist Arthur Roberts published their report on the first radioiodine therapy (1941) for Graves' disease, [ 123 ] [ 124 ]  at that time still predominantly using the  130 iodine isotope with a half-life of 12.4 hours. [ 125 ]  At the same time,  Joseph Gilbert Hamilton  (1907-1957) and  John Hundale Lawrence  (1904-1991) performed the first therapy with  131 iodine, the isotope still used today. [ 125 ]


Radioiodine therapy is subject to special legal regulations in many countries, and in Germany may only be performed on an inpatient basis. There are approximately 120 treatment centers in Germany (as of 2014), performing approximately 50,000 treatments per year. [ 126 ]  In Germany, the minimum length of stay is 48 hours. Discharge depends on the residual activity remaining in the body. In 1999, the limit for residual activity was raised. The dose rate may not exceed 3.5  μSv  per hour at a distance of 2 meters from the patient, which means that a radiation exposure of 1 mSv may not be exceeded within one year at a distance of 2 meters. This corresponds to a residual activity of about 250  MBq . Similar regulations exist in Austria.


In Switzerland, a maximum radiation exposure of 1 mSv per year and a maximum of 5 mSv per year for the patient's relatives may not be exceeded. [ 127 ]  After discharge following radioiodine therapy, a maximum dose rate of 5 μSv per hour at a distance of 1 meter is permitted, which corresponds to a residual activity of approximately 150 MBq. [ 128 ]  In the event of early discharge, the supervisory authority must be notified up to a dose rate of 17.5 μSv/h; above 17.5 μSv/h, permission must be obtained. If the patient is transferred to another ward, the responsible  radiation protection officer  must ensure that appropriate radiation protection measures are taken there, e.g. that a temporary  control area  is set up.


Scintigraphy  is a nuclear medicine procedure in which low-level radioactive substances are injected into the patient for diagnostic purposes. These include  bone scintigraphy ,  thyroid scintigraphy ,  octreotide scintigraphy , and, as a further development of the procedure, single photon emission computed tomography (SPECT). For example,  201 Tl  thallium(I) chloride , technetium compounds ( 99m Tc tracer,  99m technetium tetrofosmin), PET tracers (with radiation exposure of 1100 MBq each with  15 O-water, 555 MBq with  13 N  ammonia , or 1850 MBq with  82 Rb  rubidium chloride ) are used in myocardial scintigraphy to diagnose blood flow conditions and function of the heart muscle (myocardium). The examination with 74 MBq  201 Thallium Chloride causes a radiation exposure of about 16 mSv (effective dose equivalent), the examination with 740 MBq  99m Technetium-MIBI about 7 mSv. [ 129 ]  Metastable  99m Tc is by far the most important nuclide used as a tracer in scintigraphy because of its short half-life, the 140  keV  gamma radiation it emits, and its ability to bind to many active biomolecules. Most of this radiation is excreted after the examination. The remaining  99m Tc  decays rapidly to  99 Tc with a half-life of 6 hours. This has a long half-life of 212,000 years and, because of the relatively weak beta radiation released during its decay, contributes only a small amount of additional radiation exposure over the remaining lifetime. [ 130 ]  In the United States alone, approximately seven million individual doses of  99m Tc are administered each year for diagnostic purposes.


To reduce radiation exposure, the  American Society of Nuclear Cardiology  (ASNC) issued dosage recommendations in 2010. The effective dose is 2.4 mSv for  13 N-ammonia, 2.5 mSv for  15 O-water, 7 mSv for  18 F- fluorodeoxyglucose , and 13.5 mSv for  82 Rb-rubidium chloride. [ 131 ]  Compliance with these recommendations is expected to reduce the average radiation exposure to = 9 mSv. The  Ordinance on Radioactive Drugs or Drugs Treated with Ionizing Radiation


§ 2
 AMRadV  (in German)
regulates the approval procedures for the marketability of radioactive drugs. [ 132 ]


Brachytherapy  is used to place a sealed radioactive source inside or near the body to treat cancer, such as prostate cancer. Afterloading brachytherapy is often combined with  teletherapy , which is external radiation delivered from a greater distance than brachytherapy. It is not classified as a nuclear medicine procedure, although like nuclear medicine, it uses the radiation emitted by radionuclides. After initial interest in brachytherapy in the early 20th century, its use declined in the mid-20th century because of the radiation exposure to physicians from manual handling of the radiation sources. [ 133 ] [ 134 ]  It was not until the development of remote-controlled afterloading systems and the use of new radiation sources in the 1950s and 1960s that the risk of unnecessary radiation exposure to physicians and patients was reduced. [ 135 ]  In the afterloading procedure, an empty, tubular applicator is inserted into the target volume (e.g., the  uterus ) before the actual therapy and, after checking the position, loaded with a radioactive preparation. The preparation is located at the tip of a steel wire that is advanced and retracted step by step under computer control. After the pre-calculated time, the source is withdrawn into a safe and the applicator is removed. The procedure is used for breast cancer, bronchial carcinoma or oral floor carcinoma, among others.  Beta emitters  such as  90 Sr or  106 Ru or  192 Ir are used. As a precaution, patients undergoing permanent brachytherapy are advised not to hold small children immediately after treatment and not to be in the vicinity of pregnant women, since low-dose radioactive sources (seeds) remain in the body after treatment with permanent brachytherapy. This is to protect the particularly radiation-sensitive tissues of a fetus or infant.


Radioactive  thorium  was used in the 1950s and 60s to treat tuberculosis and other benign diseases (including children), with serious consequences (see Peteosthor). A stabilized  suspension  of  colloidal   thorium(IV) oxide , co-developed by  António Egas Moniz  (1874-1954), [ 136 ]  was used from 1929 under the trade name  Thorotrast  as an X-ray contrast agent for  angiography  in several million patients worldwide until it was banned in the mid-1950s. It accumulates in the  reticulohistiocytic system  and can lead to cancer due to locally increased radiation exposure. The same is true for  cholangiocarcinoma  and  angiosarcoma  of the liver, two rare liver cancers. Carcinomas of the  paranasal sinuses  have also been described following administration of Thorotrast. Typical onset of disease is 30–35 years after exposure. The  biological half-life  of Thorotrast is approximately 400 years. [ 137 ] [ 138 ]  The largest study in this area was conducted in Germany in 2004 and showed a particularly high mortality rate among patients exposed in this way. The  median   life expectancy  over a seventy-year observation period was 14 years shorter than in the comparison group. [ 139 ]


After the U.S. atomic bombs were dropped on Hiroshima and Nagasaki on August 6 and 9, 1945, an additional 130,000 people - in addition to the 100,000 immediate victims - died from the effects of radiation by the end of 1945. Some experienced the so-called  walking ghost phase , an acute radiation sickness caused by a high equivalent dose of 6 to 20 Sievert after a lethal whole-body dose. The phase describes the period of apparent recovery of a patient between the onset of the first massive symptoms and the inevitable death. [ 140 ]  In the years that followed, a number of deaths from radiation-induced diseases were added. In Japan, the radiation-damaged survivors are called  hibakusha  ( Japanese :  被爆者 ,  lit.   ''Explosion victim'') and are conservatively estimated to number about 100,000. [ 141 ]


In 1946, the  Atomic Bomb Casualty Commission  (ABCC) was established by the  National Research Council  of the  National Academy of Sciences  by order of U.S. President  Harry S. Truman  to study the long-term effects of radiation on survivors of the atomic bombings. In 1975, the ABCC was replaced by the Radiation Effects Research Foundation (RERF). [ 142 ]  Organizations such as the  United Nations Scientific Committee on the Effects of Atomic Radiation  (UNSCEAR), founded in 1955, [ 143 ]  and the  National Academy of Sciences - Advisory Committee on the Biological Effects of Ionizing Radiation  (BEIR Committee), [ 144 ]  founded in 1972, analyze the effects of radiation exposure on humans on the basis of atomic bomb victims who have been examined and, in some cases, medically monitored for decades. They determine the course of the  mortality  rate as a function of the age of the radiation victims in comparison with the spontaneous rate, and also the dose-dependency of the number of additional deaths. To date, 26 UNSCEAR reports have been published and are available online, most recently in 2017 on the effects of the Fukushima nuclear accident. [ 145 ]


By 1949, Americans felt increasingly threatened by the possibility of nuclear war with the Soviet Union and sought ways to survive a nuclear attack. The U.S. Federal Civil Defense Administration (USFCDA) was created by the government to educate the public on how to prepare for such an attack. In 1951, with the help of this agency, a children's educational film was produced in the U.S. called  Duck and Cover , in which a turtle demonstrates how to protect oneself from the immediate effects of an atomic bomb explosion by using a coat, tablecloths, or even a newspaper. [ 146 ]


Recognizing that existing medical capacity would not be sufficient in an emergency, dentists were called upon to either assist physicians in an emergency or, if necessary, to provide assistance themselves. To mobilize the profession with the help of a prominent representative, dentist Russell Welford Bunting (1881-1962), dean of the  University of Michigan  Dental School, was recruited in July 1951 as a dental consultant to the USFCDA. [ 147 ] [ 148 ]


The American physicist  Karl Ziegler Morgan  (1907-1999) was one of the founders of radiation health physics. In later life, after a long career with the Manhattan Project and  Oak Ridge National Laboratory  (ORNL), he became a critic of nuclear power and nuclear weapons production. Morgan was Director of Health Physics at ORNL from the late 1940s until his retirement in 1972. In 1955, he became the first president of the  Health Physics Society  and served as editor of the journal Health Physics from 1955 to 1977. [ 149 ]


Nuclear fallout shelters  are designed to protect for an extended period. Due to the nature of nuclear warfare, such shelters must be completely self-sufficient for long periods. In particular, because of the radioactive contamination of the surrounding area, such a facility must be able to survive for several weeks. In 1959, top-secret construction began in Germany on a government bunker in the  Ahr  valley. In June 1964, 144 test persons survived for six days in a civilian nuclear bunker. The bunker in Dortmund had been built during the Second World War and had been converted at great expense in the early 1960s into a nuclear-weapon-proof building. However, it would be impossible to build a bunker for millions of German citizens. [ 150 ]  The Swiss Army built about 7800 nuclear fallout shelters in 1964. In the United States in particular, but also Europe, citizens built private fallout shelters in their front yards on their initiative. This construction was largely kept secret because the owners feared that third parties might take possession of the bunker in the event of a crisis.


On July 16, 1945, the first  atomic bomb test  took place near the town of  Alamogordo  (New Mexico, USA). As a result of the atmospheric nuclear weapons tests carried out by the United States, the Soviet Union, France, Great Britain, and China, the Earth's atmosphere became increasingly contaminated with fission products from these tests from the 1950s onwards. The  radioactive fallout  landed on the earth's surface and ended up in plants and, via animal feed, in food of animal origin. Ultimately, they entered the human body and could be detected in bones and teeth as strontium-90, among other things. [ 152 ]  The radioactivity in the field was measured with a gamma scope, as shown at the  air raid  equipment exhibition  in Bad Godesberg in 1954. [ 153 ]  Around 180 tests were carried out in 1962 alone. The extent of the radioactive contamination of the food sparked worldwide protests in the early 1960s.


During World War II and the Cold War, the  Hanford Site  produced plutonium for U.S. nuclear weapons for more than 50 years. The  plutonium  for the first plutonium bomb, Fat Man, also came from there. Hanford is considered the most radioactively contaminated site in the Western Hemisphere. [ 154 ]  A total of 110,000 tons of nuclear fuel was produced there. In 1948, a radioactive cloud leaked from the plant. The amount of  131 I  alone was 5500  curies . Most of the reactors at Hanford were shut down in the 1960s, but no disposal or decontamination was done. After preliminary work, the world's largest  decontamination  operation began at Hanford in 2001 to safely dispose of the radioactive and toxic waste. In 2006, some 11,000 workers were still cleaning up contaminated buildings and soil to reduce radiation levels at the site to acceptable levels. This work is expected to continue until 2052. [ 155 ]  It is estimated that more than four million liters of radioactive liquid have leaked from storage tanks.


It was only after the two superpowers agreed on a Partial Test Ban Treaty in 1963, which allowed only underground nuclear weapons testing, that the level of radioactivity in food began to decline.  Shields Warren  (1896-1980), one of the authors of a report on the effects of the atomic bombs dropped on Japan, was criticized for downplaying the effects of residual radiation in Hiroshima and Nagasaki, [ 156 ]  but later warned of the dangers of fallout. Fallout refers to the spread of radioactivity in the context of a given meteorological situation. A model experiment was conducted in 2008. [ 157 ]


The  International Campaign to Abolish Nuclear Weapons  (ICAN) is an international alliance of non-governmental organizations committed to the elimination of all nuclear weapons through a binding international treaty - a Nuclear Weapons Convention. ICAN was founded in 2007 by IPPNW ( International Physicians for the Prevention of Nuclear War ) and other organizations at the  Nuclear Non-Proliferation Treaty  Conference in Vienna and launched in twelve countries. Today, 468 organizations in 101 countries are involved in the campaign (as of 2017). [ 158 ]  ICAN was awarded the 2017  Nobel Peace Prize . [ 159 ]


A radioprotector is a  pharmacon  that, when administered, selectively protects healthy cells from the toxic effects of  ionizing radiation . The first work with radioprotectors began as part of the  Manhattan Project , a military research project to develop and build an atomic bomb.


Iodine  absorbed by the body is almost completely stored in the  thyroid gland  and has a biological  half-life  of about 120 days. If the iodine is radioactive ( 131 I), it can irradiate and damage the thyroid gland in high doses during this time. Because the thyroid gland can only absorb a limited amount of iodine, prophylactic administration of non-radioactive iodine may result in iodine blockade.  Potassium iodide  in tablet form (colloquially known as "iodine tablets") reduces the uptake of radioactive iodine into the thyroid by a factor of 90 or more, thus acting as a radioprotector. [ 160 ]  All other radiation damage remains unaffected by taking iodine tablets. In Germany, the Potassium Iodide Ordinance (KIV) was enacted in 2003 to ensure "the supply of the population with potassium iodide-containing  medicines  in the event of radiological incidents".


§ 1
 kiv  (in German)
Potassium iodide is usually stored in communities near nuclear facilities for distribution to the population in the event of a disaster. [ 161 ]  People over the age of 45 should not take iodine tablets because the risk of side effects is higher than the risk of developing thyroid cancer. In Switzerland, as a precautionary measure, tablets have been distributed every five years since 2004 to the population living within 20 km of nuclear power plants (from 2014, 50 km). [ 162 ] [ 163 ]  In Austria, large stocks of iodine tablets have been kept in pharmacies, kindergartens, schools, the army and the  federal reserve  since 2002. [ 164 ]


Thanks to the protective function of radioprotectors, the dose of radiation used to treat malignant tumors (cancer) can be increased, thereby increasing the effectiveness of the therapy. [ 165 ]  There are also  radiosensitizers , which increase the sensitivity of malignant tumor cells to ionizing radiation. [ 166 ]  As early as 1921, the German radiologist  Hermann Holthusen  (1886-1971) described that oxygen increases the sensitivity of cells. [ 167 ]


Founded in 1957 as a sub-organization of the  Organization for Economic Cooperation and Development  (OECD), the  Nuclear Energy Agency  (NEA) pools the scientific and financial resources of participating countries' nuclear research programs. It operates various databases and also manages the  International Reporting System for Operating Experience  (IRS or IAEA/NEA Incident Reporting System) of the  International Atomic Energy Agency  (IAEA). The IAEA records and investigates radiation accidents that have occurred worldwide in connection with nuclear medical procedures and the disposal of related materials. [ 168 ]


The  International Nuclear and Radiological Event Scale  (INES) is a scale for safety-related events, in particular nuclear incidents and accidents in nuclear facilities. It was developed by an international group of experts and officially adopted in 1990 by the International Atomic Energy Agency (IAEA) and the Nuclear Energy Agency of the Organization for Economic Cooperation and Development (OECD). [ 169 ]  The purpose of the scale is to inform the public quickly about the safety significance of an event by means of a comprehensible classification of events.


At the end of its useful life, the proper disposal of the remaining high activity is of paramount importance. Improper disposal of the radionuclide  cobalt-60 , used in  cobalt guns  for radiotherapy, has led to serious radiation accidents, such as the  Ciudad Juárez (Mexico) radiological accident  in 1983/84, [ 170 ]  the  Goiânia (Brazil) accident  in 1987, the  Samut Prakan (Thailand) nuclear accident  in 2000, and the Mayapuri (India) accident in 2010. [ 171 ]


Eleven  Therac-25   linear accelerators  were built by the Canadian company  Atomic Energy of Canada Limited  (AECL) between 1982 and 1985 and installed in clinics in the United States and Canada.  Software errors  and a lack of quality assurance led to a serious malfunction that killed three patients and seriously injured three others between June 1985 and 1987 before appropriate countermeasures were taken. The radiation exposure in the six cases was subsequently estimated to be between 40 and 200  Gray ; normal treatment is equivalent to a dose of less than 2 Gray. [ 172 ] [ 173 ]


Around 1990, about one hundred cobalt guns were still in use in Germany. In the meantime,  electron linear accelerators  were introduced and the last cobalt gun was decommissioned in 2000. [ 174 ]


The  Fukushima nuclear accident  in 2011 reinforced the need for proper safety management and the derivation of safety indicators regarding the frequency of errors and incorrect actions by personnel, i.e., the  human factor . [ 175 ]  The  Nuclear Safety Commission of Japan  ( Japanese :  原子力安全委員会 ) was a body of scientists that advised the Japanese government on nuclear safety issues. The commission was established in 1978, [ 176 ]  but was dissolved after the Fukushima nuclear disaster on September 19, 2012, and replaced by the  Genshiryoku Kisei Iinkai [ 177 ]  ( Japanese :  原子力規制委員会 ,  lit.   'Nuclear Regulatory Committee'). It is an independent agency ( gaikyoku , "external office") of the Japanese  Ministry of the Environment  that regulates and monitors the safety of Japan's  nuclear power plants  and related facilities.


As a result of the  Chernobyl nuclear disaster  in 1986, the IAEA coined the term " safety culture " for the first time in 1991 to draw attention to the importance of human and organizational issues for the safe operation of nuclear power plants.


After this nuclear disaster, the sand in children's playgrounds in Germany was removed and replaced with uncontaminated sand to protect children who were most vulnerable to radioactivity. Some families temporarily left Germany to escape the fallout.  Infant mortality  increased significantly by 5% in 1987, the year after Chernobyl. [ 178 ]  In total, 316 more newborns died that year than statistically expected. In Germany, the  caesium 137  inventories from the Chernobyl nuclear disaster in soil and food decrease by 2-3% each year; however, the contamination of game and mushrooms was still comparatively high in 2015, especially in Bavaria; there are several cases of  game meat , especially  wild boar , exceeding the limits. [ 179 ]  However, controls are insufficient. [ 180 ] [ 181 ]


"In particular, wild boars in southern Bavaria are repeatedly found to have a very high radioactive contamination of over 10,000 Becquerel/kg. The limit is 600 Becquerel/kg. For this reason, the Bavarian Consumer Center advises against eating wild boar from the Bavarian Forest and south of the Danube too often. Whoever buys wild boar from a hunter, should ask for the measurement protocol."


Between 1969 and 1982,  conditioned  low- and intermediate-level radioactive waste was disposed of in the Atlantic Ocean at a depth of about 4,000 meters under the supervision of the  Nuclear Energy Agency  (NEA) of the  Organization for Economic Cooperation and Development  (OECD) in accordance with the provisions of the European Convention on the Prevention of Marine Pollution by Dumping of Waste of All Kinds (London Dumping Convention of June 11, 1974). This was carried out jointly by several European countries. [ 27 ]  Since 1993, international treaties have prohibited the dumping of radioactive waste in the oceans. [ 183 ]  For decades, this dumping of  nuclear waste  went largely unnoticed by the public until  Greenpeace  denounced it in the 1980s.


Since the commissioning of the first commercial nuclear power plants (USA 1956, Germany 1962), various final storage concepts for radioactive materials have been proposed in the following decades, of which only storage in  deep geological formations  appeared to be safe and feasible within a reasonable period of time and was pursued further. Due to the high activity of the short-lived fission products,  spent fuel  is initially handled only under water and stored for several years in a decay pool. The water is used for cooling and also shields much of the emitted radiation. This is followed either by  reprocessing  or by decades of interim storage. Waste from reprocessing must also be stored temporarily until the heat has decreased enough to allow final disposal.  Casks  are special  containers  for the storage and transport of highly radioactive materials. Their maximum permissible dose rate is 0.35 mSv/h, of which a maximum of 0.25 mSv/h is due to neutron radiation. The safety of these transport containers has been discussed every three years since 1980 at the International Symposium on the Packaging and Transportation of Radioactive Materials (PATRAM). [ 184 ]


Following various experiments, such as the Gorleben exploratory mine or the  Asse mine , a working group on the selection procedure for repository sites (AkEnd) developed recommendations for a new selection procedure for repository sites between 1999 and 2002. [ 185 ]  In Germany, the  Site Selection Act  was passed in 2013 and the  Act on the Further Development of the Site Search  was passed on March 23, 2017. A suitable site is to be sought throughout Germany and identified by 2031. In principle, crystalline (granite), salt or clay rock types can be considered for a repository. There will be no "ideal" site. The "best possible" site will be sought. Mining areas and regions where volcanoes have been active or where there is a risk of earthquakes are excluded. Internationally, experts are advocating storage in rock formations several hundred meters below the earth's surface. This involves building a repository mine and storing the waste there. It is then permanently sealed. Geological and technical barriers surrounding the waste are designed to keep it safe for thousands of years. For example, 300 meters of rock will separate the repository from the earth's surface. [ 186 ]  It will be surrounded by a 100-meter-thick layer of granite, salt or clay. The first waste is not expected to be stored until 2050. [ 187 ]


The Federal Office for the Safety of Nuclear Waste Management (BfE) took up its activities on September 1, 2004. [ 188 ]  Its remit includes tasks relating to nuclear safety, the safety of nuclear waste management, the site selection procedure including research activities in these areas and, later on, further tasks in the area of licensing and supervision of repositories.


In the USA,  Yucca Mountain  was initially selected as the final storage site, but this project was temporarily halted in February 2009. Yucca Mountain was the starting point for an investigation into atomic semiotics.


The operation of nuclear power plants and other nuclear facilities produces radioactive materials that can have lethal health effects for thousands of years. It is important to note that there is no institution capable of maintaining the necessary knowledge of the dangers over such periods, and of ensuring that warnings about the dangers of nuclear waste in nuclear repositories will be understood by posterity in the distant future. A few years ago, even the capsules of the radionuclide cobalt-60, which were appropriately labeled, went unnoticed. Improper disposal led to the opening of these capsules, resulting in fatal consequences. The dimensions of time exceed previous human standards. For instance, cuneiform writing, which is only about 5000 years old (about 150 human generations), can only be understood after a long period of research and by experts. In 1981, research into the development of atomic semiotics began in the USA, [ 189 ]  in the German-speaking world,  Roland Posner  (1942-2020) of the Center for Semiotics at  Technische Universität Berlin  worked on this in 1982/83. [ 190 ]  In the USA, the time horizon for such warning signs was set at 10,000 years; later, as in Germany, it was set at a period of one million years, which would correspond to about 30,000 (human) generations. To date, no satisfactory solution to this problem has been found.


In 1912,  Victor Franz Hess  (1883-1964) discovered (secondary)  cosmic rays  in the Earth's atmosphere using balloon flights. For this discovery he received the  Nobel Prize in Physics  in 1936. He was also one of the "martyrs" of early radiation research and had to undergo a thumb amputation and  larynx  surgery due to radium burns. [ 191 ]  In the United States and the Soviet Union, balloon flights to altitudes of about 30 km, followed by  parachute jumps from the stratosphere , were conducted before 1960 to study human exposure to cosmic radiation in space. The American  Manhigh  and  Excelsior  projects with  Joseph Kittinger  (1928-2022) became particularly well known, but the Soviet parachutist  Yevgeny Andreyev  (1926-2000) also set new records. [ 192 ]


High-energy radiation from  space  is much stronger at high altitudes than at sea level. The radiation exposure of flight crews and air travelers is therefore increased. The  International Commission on Radiological Protection  (ICRP) has issued recommendations for dose limits, which were incorporated into European law in 1996 and into the German Radiation Protection Ordinance in 2001. Radiation exposure is particularly high when flying in the polar regions or over the  polar route . [ 193 ]  The average annual effective dose for aviation personnel was 1.9 mSv in 2015 and 2.0 mSv in 2016. The highest annual personal dose was 5.7 mSv in 2015 and 6.0 mSv in 2016. [ 194 ]  The collective dose for 2015 was about 76 person-Sv. This means that  flight personnel  are among the occupational groups in Germany with the highest radiation exposure in terms of collective dose and average annual dose. [ 195 ]  This group also includes  frequent flyers , with Thomas Stuker holding the "record" - also in terms of radiation exposure - by reaching the 10 million mile mark with  United Airlines  MileagePlus on 5,900 flights between 1982 and the summer of 2011. [ 196 ]  In 2017, he passed the 18 million mile mark.


The program  EPCARD  (European Program Package for the Calculation of Aviation Route Dose) was developed at the  University of Siegen  and the  Helmholtz Munich  and can be used to calculate the dose from all components of natural penetrating cosmic radiation on any flight route and flight profile - also online. [ 197 ]


From the earliest  crewed space flights  to the first  moon landing  and the construction of the  International Space Station  (ISS), radiation protection has been a major concern.  Spacesuits  used for extravehicular activities are coated on the outside with  aluminum , which largely protects against cosmic radiation. The largest international research project to determine the  effective dose  or effective dose equivalent was the  Matryoshka experiment  in 2010, named after the Russian  Matryoshka  dolls, because it uses a human-sized phantom that can be cut into slices. [ 198 ]  As part of Matroshka, an  anthropomorphic  phantom was exposed to the outside of the space station for the first time to simulate an  astronaut  performing an  extravehicular activity  (spacewalk) and determine their exposure to radiation. [ 199 ] [ 200 ] Microelectronics  on  satellites  must also be protected from radiation.


Japanese scientists from the  Japan Aerospace Exploration Agency  (JAXA) have discovered a huge cave on the moon with their  Kaguya  lunar probe, which could offer astronauts protection from dangerous radiation during future lunar landings, especially during the planned stopover of a Mars mission. [ 201 ] [ 202 ]


As part of a  human mission to Mars , astronauts must be protected from cosmic radiation. During  Curiosity 's mission to Mars, a  Radiation Assessment Detector  (RAD) was used to measure radiation exposure. [ 203 ]  The radiation exposure of 1.8 millisieverts per day was mainly due to the constant presence of high-energy galactic particle radiation. In contrast, radiation from the sun accounted for only about three to five percent of the radiation levels measured during Curiosity's flight to Mars. On the way to Mars, the RAD instrument detected a total of five major radiation events caused by  solar flares . [ 204 ]  To protect the astronauts, a  plasma   bubble  will surround the spacecraft as an energy shield and its  magnetic field  will protect the crew from cosmic radiation. This would eliminate the need for conventional radiation shields, which are several centimeters thick and correspondingly heavy. [ 205 ]  In the Space Radiation Superconducting Shield (SR2S) project, which was completed in December 2015,  magnesium diboride  was found to be a suitable material for generating a suitable  force field . [ 206 ]


Dosimeters  are instruments used to measure radiation dose - as absorbed dose or dose equivalent - and are an important cornerstone of radiation protection.


At the October 1907 meeting of the  American Roentgen Ray Society ,  Rome Vernon Wagner , an X-ray tube manufacturer, reported that he had begun carrying a photographic plate in his pocket and developing it every evening. This allowed him to determine how much radiation he had been exposed to. This was the forerunner of the  film dosimeter . His efforts came too late, as he had already developed cancer and died six months after the conference.


In the 1920s, the  physical chemist  John Eggert (1891-1973) played a key role in the introduction of  film dosimetry  for routine personal monitoring. Since then, it has been successively improved and, in particular, the evaluation technique has been automated since the 1960s. [ 207 ]  At the same time,  Hermann Joseph Muller  (1890-1967) discovered  mutations  as genetic consequences of X-rays, for which he was awarded the Nobel Prize in 1946. At the same time, the  roentgen  (R) was introduced as a unit for quantitative measurement of radiation exposure.


A dosimeter for film is divided into multiple segments, each containing a light- or radiation-sensitive film surrounded by layers of copper and lead with varying thickness. The degree of radiation penetration determines whether the segment is not blackened or blackened to varying degrees. The absorbed radiation effect during the measurement time is summed up, and the radiation dose can be determined from the blackening. Guidelines for evaluation exist, with those for Germany being published in 1994 and last updated on December 8, 2003. [ 208 ]


With the invention of the Geiger  gaseous ionization detector  in 1913, which became the Geiger-Müller gaseous ionization detector in 1928 - named after the physicists  Hans Geiger  (1882-1945) and Walther Müller (1905-1979) - the individual particles or quanta of ionizing radiation could be detected and measured. Detectors developed later, such as proportional counters or  scintillation counters , which not only "count" but also measure energy and distinguish between types of radiation, also became important for radiation protection. Scintillation measurement is one of the oldest methods of detecting ionizing radiation or X-rays; originally, a  zinc sulfide screen  was held in the path of the beam and the scintillation events were either counted as flashes or, in the case of X-ray diagnostics, viewed as an image. A scintillation counter known as a  spinthariscope  was developed in 1903 by  William Crookes  (1832-1919) [ 209 ]  and used by  Ernest Rutherford  (1871-1937) to study the scattering of alpha particles from atomic nuclei.


Lithium fluoride  had already been proposed in the USA in 1950 by  Farrington Daniels  (1889-1972), Charles A. Boyd and  Donald F. Saunders  (1924-2013) for solid-state dosimetry using  thermoluminescent dosimeters . The intensity of the thermoluminescent light is proportional to the amount of radiation previously absorbed. This type of dosimetry has been used since 1953 in the treatment of cancer patients and wherever people are occupationally exposed to radiation. [ 210 ]  The thermoluminescence dosimeter was followed by OSL dosimetry, which is not based on heat but on  optically stimulated luminescence  and was developed by  Zenobia Jacobs  and Richard Roberts at the  University of Wollongong  (Australia). [ 211 ]  The detector emits the stored energy as light. The light output, measured with  photomultipliers , is then a measure of the dose. [ 212 ]


Since 2003,  whole-body counters  have been used in radiation protection to monitor the absorption (incorporation) of radionuclides in people who handle gamma-emitting open radioactive materials and who may be contaminated through food, inhalation of dusts and gases, or open wounds. ( α  and  β  emitters are not measurable). [ 213 ]


Constancy testing is the verification of reference values as part of  quality assurance  in  x-ray diagnostics ,  nuclear medicine  diagnostics, and  radiotherapy . National regulations specify [ 214 ] [ 215 ]  which parameters are to be tested, which limits are to be observed, which test methods are to be used, and which test samples are to be used. In Germany, the Radiation Protection in Medicine Directive and the relevant DIN 6855 standard in nuclear medicine require regular (in some cases daily) constancy testing.  Test sources  are used to check the response of probe measuring stations as well as  in vivo  and  in vitro  measuring stations. Before starting the tests, the background count rate and the setting of the energy window must be checked every working day, and the settings and the yield with reproducible geometry must be checked at least once a week with a suitable test source, e.g. 137Caesium (DIN 6855-1). [ 216 ]  The reference values for the constancy test are determined during the acceptance test.


Compact test specimens for medical X-ray images were not created until 1982. Prior to this, the patient himself often served as the object for producing X-ray test images. Prototypes of such an X-ray phantom with integrated structures were developed by Thomas Bronder at the  Physikalisch-Technische Bundesanstalt . [ 217 ] [ 218 ]


A water phantom is a Plexiglas container filled with distilled water that is used as a substitute for living tissue to test electron linear accelerators used in radiation therapy. According to regulatory requirements, water phantom testing must be performed approximately every three months to ensure that the radiation dose delivered by the treatment system is consistent with the  radiation planning . [ 219 ]


The Alderson-Rando phantom, invented by  Samuel W. Alderson  (1914-2005), has become the standard X-ray phantom. It was followed by the Alderson Radio Therapy (ART) phantom, which he patented in 1967. The ART phantom is cut horizontally into 2.5 cm thick slices. Each slice has holes sealed with bone-equivalent, soft-tissue-equivalent, or lung-equivalent pins that can be replaced by thermoluminescent dosimeters. Alderson is also known as the inventor of the  crash test dummy . [ 220 ]


As a result of accidents or improper use and disposal of radiation sources, a significant number of people are exposed to varying degrees of radiation. Radioactivity and  local dose measurements  are not sufficient to fully assess the effects of radiation. To retrospectively determine the individual radiation dose, measurements are made on teeth, i.e. on biological, endogenous materials.  Tooth enamel  is particularly suitable for the detection of ionizing radiation due to its high mineral content ( hydroxyapatite ), which has been known since 1968 thanks to the research of John M. Brady, Norman O. Aarestad and Harold M. Swartz. [ 221 ]  The measurements are performed on  milk teeth , preferably molars, using  electron paramagnetic resonance spectroscopy  (ESR, EPR). The concentration of  radicals  generated by ionizing radiation is measured in the mineral part of the tooth. Due to the high stability of the radicals, this method can be used for dosimetry of long past exposures. [ 222 ] [ 223 ]


Since about 1988, in addition to physical dosimetry, biological dosimetry has made it possible to reconstruct the individual dose of ionizing radiation. This is especially important for unforeseen and accidental exposures, where radiation exposures occur without physical dose monitoring. Biological markers, particularly cytogenetic markers in blood lymphocytes, are used for this purpose. Techniques for detecting radiation damage include analyzing dicentric chromosomes after acute radiation exposure. Dicentric chromosomes result from defective repair of chromosome breaks in two chromosomes, resulting in two centromeres instead of one like undamaged chromosomes. Symmetric translocations, detected through fluorescence in situ hybridization (FISH), are used after chronic or long-term exposure to radiation. The micronucleus test and the premature chromosome condensation (PCC) test are available to measure acute exposure. [ 224 ] [ 225 ]


In principle, reducing the exposure of the human organism to ionizing radiation to zero is not possible and perhaps not even sensible. The human organism has been accustomed to natural radioactivity for thousands of years and ultimately this also triggers  mutations  (changes in  genetic material ), which are the cause of the development of life on earth. The mutation-inducing effect of high-energy radiation was first demonstrated in 1927 by  Hermann Joseph Muller  (1890-1967). [ 226 ]


Three years after its establishment in 1958, the United Nations Scientific Committee on the Effects of Atomic Radiation adopted the Linear No-Threshold  (LNT) model  - a linear dose-effect relationship without a threshold - largely at the instigation of the Soviet Union. The dose-response relationship measured at high doses was extrapolated linearly to low doses. There would be no threshold, since even the smallest amounts of ionizing radiation would trigger some biological effect. [ 227 ]  The LNT model ignores not only possible  radiation hormesis , but also the known ability of  cells  to repair  genetic damage  and the ability of the organism to remove damaged cells. [ 228 ] [ 229 ] [ 230 ]  Between 1963 and 1969,  John W. Gofman  (1918-2007) and  Arthur R. Tamplin  of the  University of California, Berkeley , conducted research for the  United States Atomic Energy Commission  (USAEC, 1946-1974) investigating the relationship between radiation doses and cancer incidence. Their findings sparked a fierce controversy in the United States beginning in 1969. Starting in 1970,  Ernest J. Sternglass , a radiologist at the  University of Pittsburgh , published several studies describing the effect of radiation from nuclear tests and the vicinity of nuclear power plants on infant mortality. In 1971, the UASEC reduced the maximum allowable radiation dose by a factor of 100. Subsequently, nuclear technology was based on the principle of "As Low As Reasonably Achievable" ( ALARA ). This was a coherent principle as long as it was assumed that there was no threshold and that all doses were additive. In the meantime, a transition to "As High As Reasonably Safe" (AHARS) is increasingly being discussed. For the question of evacuation after accidents, a transition to AHARS seems absolutely necessary. [ 231 ]  In both the Chernobyl and Fukushima cases, hasty, poorly organized and poorly communicated evacuations caused psychological and physical damage to those affected - including documented deaths in the case of Fukushima. [ 232 ] [ 233 ] [ 234 ]  By some estimates, this damage is greater than would have been expected had the evacuation not taken place. [ 235 ] [ 236 ] [ 237 ]  Voices such as Geraldine Thomas therefore question such evacuations in principle and call for a transition to shelter-in-place wherever possible. [ 238 ] [ 239 ]


The British physicist and radiologist and founder of  radiobiology   Louis Harold Gray  (1905-1965) introduced the unit  Rad  (acronym for radiation absorbed dose) in the 1930s, which was renamed  Gray  (Gy) after him in 1978. One gray is a mass-specific quantity and corresponds to the energy of one  joule  absorbed by one kilogram of body weight. Acute whole-body exposures in excess of four Gy are usually fatal to humans.


The different types of radiation  ionize  to different degrees. Ionization is any process in which one or more electrons are removed from an atom or molecule, leaving the atom or molecule as a positively charged ion ( cation ). Each type of radiation is therefore assigned a dimensionless weighting factor that expresses its biological effectiveness. For X-rays,  gamma  and beta radiation, the factor is one, alpha radiation reaches a factor of twenty, and for  neutron radiation  it is between five and twenty, depending on the energy.


Multiplying the absorbed dose in Gy by the weighting factor gives the  equivalent dose , expressed in Sievert (Sv). It is named after the Swedish physician and physicist  Rolf Maximilian Sievert  (1896-1966). Sievert was the founder of radiation protection research and developed the Sievert chamber in 1929 to measure the intensity of X-rays. He founded the  International Commission on Radiation Units and Measurements  (ICRU) and later became chairman of the  International Commission on Radiological Protection  (ICRP). [ 240 ]  The ICRU and ICRP specify differently defined weighting factors that apply to environmental measurements (quality factor) and body-related dose equivalent data (radiation weighting factor).


In relation to the body, the relevant dose term is the  Organ Equivalent Dose  (formerly "Organ Dose"). This is the dose equivalent averaged over an organ. Multiplied by organ-specific tissue weighting factors and summed over all organs, the  effective dose  is obtained, which represents a dose balance. In relation to environmental measurements, the ambient dose equivalent or local dose is relevant. Its increase over time is called the local dose rate.


Even at very low effective doses, stochastic effects (genetic and cancer risk) are expected. At effective doses above 0.1 Sv, deterministic effects also occur (tissue damage up to radiation sickness at very high doses). Correspondingly high radiation doses are now only given in units of Gy. Natural radiation exposure in Germany, with an annual average effective dose of about 0.002 Sv, is well below this range. [ 241 ]


In 1931, the U.S. Advisory Committee on X-Ray and Radium Protection (ACXRP, now the National Council on Radiation Protection and Measurements, NCRP), founded in 1929, published the results of a study on the so-called tolerance dose, on which a scientifically based radiation protection guideline was based. Exposure limits were gradually lowered. In 1936 the tolerance dose was 0.1 R/day. [ 9 ]  The unit "R" (the X-ray) from the  CGS unit system  has been obsolete since the end of 1985. Since then, the  SI  unit of ion dose has been " coulomb  per kilogram".


After World War II, the concept of tolerance dose was replaced by that of maximum permissible dose and the concept of relative biological effectiveness was introduced. The limit was set in 1956 by the  National Council on Radiation Protection & Measurements  (NCRP) and the  International Commission on Radiological Protection  (ICRP) at 5 rem (50  mSv ) per year for radiation workers and 0.5 rem per year for the general population. The unit  Rem  as a physical measure of radiation dose (from the English roentgen equivalent in man) was replaced by the unit Sv (sievert) in 1978. This was due to the advent of nuclear energy and its associated dangers. [ 242 ]  Prior to 1991, the equivalent dose was used both as a measure of dose and as a term for the body dose that determines the course and survival of radiation sickness. ICRP Publication 60 [ 243 ]  introduced the radiation weighting factor

 w

 R

 {\displaystyle w_{R}}

  was introduced. For examples of equivalent doses as body doses, see


The origin of the concept of using a banana equivalent dose (BED) as a benchmark is unknown. In 1995, Gary Mansfield of the  Lawrence Livermore National Laboratory  found the Banana Equivalent Dose (BED) to be very useful in explaining radiation risks to the public. [ 244 ]  It is not a formally used dose.


The banana equivalent dose is the dose of ionizing radiation to which a person is exposed by eating one banana. Bananas contain  potassium . Natural potassium consists of 0.0117% of the  radioactive isotope   40 K (potassium-40) and has a specific activity of 30,346 becquerels per kilogram, or about 30 becquerels per gram. The radiation dose from eating a banana is about 0.1 μSv. [ 244 ]  The value of this reference dose is given as "1" and thus becomes the "unit of measurement" banana equivalent dose. Consequently, other radiation exposures can be compared to the consumption of one banana. For example, the average daily total radiation exposure of a person is 100 banana equivalent doses.


At 0.17 mSv per year, almost 10 percent of natural  radioactive exposure  in Germany (an average of 2.1 mSv per year) is caused by the body's own (vital) potassium. [ 245 ] [ 246 ]


The banana equivalent dose does not take into account the fact that no radioactive nuclide is  accumulated  in the body through the consumption of potassium-containing foods. The potassium content of the body is in  homeostasis  and is kept constant. [ 247 ] [ 248 ]


The  Trinity test  was the first nuclear weapon explosion conducted as part of the US  Manhattan Project . There were no warnings to residents about the fallout, nor information about shelters or possible evacuations. [ 249 ]


This was followed in 1946 by tests in the  Marshall Islands  (Operation Crossroads), [ 250 ]  as recounted by chemist Harold Carpenter Hodge (1904-1990), toxicologist for the Manhattan Project, in his lecture (1947) as president of the International Association for Dental Research. [ 251 ]  Hodge's reputation was severely damaged by historian Eileen Welsome's 1999  Pulitzer Prize -winning book The Plutonium Files - America's Secret Medical Experiments in the Cold War. She documents horrific human experiments in which the subjects (including Hodge) were unaware that they were being used as "guinea pigs" to test the safety limits of uranium and plutonium. The experiments on the unidentified subjects were continued by the  United States Atomic Energy Commission  (AEC) into the 1970s. [ 252 ]


The abuse of radiation continues to this day. [ 253 ]  During the Cold War, ethically reprehensible radiation experiments were conducted in the United States on untrained human subjects to determine the detailed effects of radiation on human health. Between 1945 and 1947, 18 people were injected with  plutonium  by Manhattan Project doctors. In Nashville, pregnant women were given radioactive mixtures. In Cincinnati, about 200 patients were irradiated over a 15-year period. In Chicago, 102 people received injections of  strontium  and  caesium  solutions. In Massachusetts, 57 children with developmental disorders were given  oatmeal  with radioactive markers. These radiation experiments were not stopped until 1993 under President  Bill Clinton . But the injustice committed was not atoned for. [ 254 ] [ 255 ]  For years,  uranium hexafluoride  caused radiation damage at a  DuPont  Company plant and to local residents. [ 256 ]  At times, the plant even deliberately released uranium hexafluoride in its heated gaseous state into the surrounding area to study the effects of the radioactive and chemically aggressive gas.


Between 1978 and 1989, vehicles were checked with  137 Cs  gamma sources at 17 border crossings between the German Democratic Republic and the Federal Republic of Germany. According to the Transit Agreement, vehicles could only be screened if there was reasonable suspicion. For this reason, the  Ministry for State Security  (Stasi) installed and operated a secret  radioactive screening technology , codenamed "Technik V," which was generally used to screen all transit passengers to detect " deserters from the Republic ." Ordinary GDR customs officers were unaware of the secret radioactive screening technology and were subject to strict "entry regulations" designed to "protect" them as much as possible from radiation exposure. Lieutenant General  Heinz Fiedler  (1929-1993), as the highest ranking border guard of the MfS, was responsible for all radiation controls. [ 257 ]  On February 17, 1995, the Radiation Protection Commission published a statement in which it said: "Even if we assume that individual persons stopped more frequently in the radiation field and that a fluoroscopy lasting up to three minutes increases the annual radiation exposure by one to a few mSv, this does not result in a dose that is harmful to health". [ 258 ]  In contrast, the designer of this type of border control calculated 15 nSv per crossing. Lorenz of the former State Office for Radiation Protection and Nuclear Safety of the GDR came up with a dose estimate of 1000 nSv, which was corrected to 50 nSv a few weeks later. [ 257 ]