---
license: cc-by-4.0
task_categories:
- image-segmentation
tags:
- medical-imaging
- ultrasound
- fetal-imaging
- segmentation
size_categories:
- 1K<n<10K
---

# HC18: Automated Fetal Head Circumference Measurement

[Original paper](https://doi.org/10.1371/journal.pone.0200412) | [Grand Challenge](https://hc18.grand-challenge.org/) | [Zenodo](https://zenodo.org/records/1327317)

## Overview
HC18 is a 2D ultrasound dataset for fetal head segmentation and circumference measurement, released as part of the HC18 Grand Challenge. It contains 1,334 standardized planes of the fetal head acquired from 551 pregnant women at Radboud UMC (Nijmegen, NL) between May 2014 and May 2015.

## Splits
- `train` (999): images + ellipse-outline annotations + per-image pixel size + ground-truth head circumference (mm)
- `test` (335): images + per-image pixel size (no annotations released; ground truth held by challenge organizers)

## Schema

**train**:
| column | type | description |
|---|---|---|
| `image` | Image | 800x540 grayscale ultrasound |
| `mask` | Image | 800x540 binary (0/255) flood-filled segmentation mask |
| `outline` | Image | 800x540 binary 1-pixel ellipse outline as shipped |
| `filename` | str | original filename, e.g. `000_HC.png` |
| `subject_id` | int | subject ID (0..805) |
| `frame_idx` | int | frame index for multi-frame subjects (1..4) |
| `pixel_size_mm` | float | pixel size in millimeters |
| `head_circumference_mm` | float | ground-truth head circumference (mm) |

**test** (same schema as train; held-out fields are `None`):
| column | type | description |
|---|---|---|
| `image` | Image | 800x540 grayscale ultrasound |
| `mask` | Image / None | always `None` (test masks are held by challenge organizers) |
| `outline` | Image / None | always `None` |
| `filename` | str | original filename |
| `subject_id` | int | parsed from filename |
| `frame_idx` | int | parsed from filename (all 1 for test) |
| `pixel_size_mm` | float | pixel size in millimeters |
| `head_circumference_mm` | float / None | always `None` (held-out ground truth) |

## Mask Format
The original annotations shipped with the dataset are 1-pixel-wide ellipse outlines (rings), not filled regions. The `mask` column is generated by flood-filling the outline interior using `scipy.ndimage.binary_fill_holes` — the standard preprocessing step described in the V-Net, Res-U-Net, and Mask-R^2 CNN papers. The original outline is preserved as the `outline` column.

## License
Creative Commons Attribution 4.0 International (CC-BY-4.0).

## Citation
```
van den Heuvel, T.L.A., de Bruijn, D., de Korte, C.L., van Ginneken, B.
Automated measurement of fetal head circumference using 2D ultrasound images.
PLoS ONE 13(8): e0200412 (2018).
```