Radiological images acquired through slice-based scanners such as Computed Tomography (CT), Magnetic Resonance Imaging (MRI) and Positron Emitting Tomography (PET) scans typically use Hounsfield Units (HU) as a method of measuring attenuation which is directly related to the density of particular anatomy. Hounsfield Units measure the signal/radiation absorbed by particular anatomy and is calibrated against a value of 0 (the density of pure water) with values being both negative (air and soft tissue) and positive (organs and bones) depending on how dense the tissue is.
3Dicom cleverly maps the distribution of HU values when loading in scans, discounts outliers and on first load, displays the most recognisable anatomy within the scan (i.e. the skin in the example below).
Furthermore, the automatic HU scaling provides greater sensitivity to the HU windowing and thresholding sliders as it scales to the maximum range measured by the scanner rather than using the full range of HU values which might not have been detected. This feature is available in all tiers of 3Dicom, from Lite through to Surgical, although 3Dicom Pro & Surgical allow for more advanced HU controls when calculating 3D volumetric measurements and segmenting anatomy for surgical planning.
If you’re interested in reviewing medical scans in a DICOM viewer that features volume rendering and Multi-planar reconstructions as standard along with the automatic HU scaling and many more features, you can download the software for Windows and/or MacOS at 3Dicom Lite.
Please note that this blog is purely for educational and marketing purposes and doesn’t not purport to be medical advice. 3Dicom is currently registered as a TGA Class 1 Visualisation device and is not approved for diagnostic purposes.