Тissue type determination based on Hounsfield units

1. Горан Коларевић, Republic of Srpska, Bosnia and Herzegovina
2. Дражан Јарош, Центар за радиотерапију, Republic of Srpska, Bosnia and Herzegovina
3. Дејан Игњатић, Аффидеа, Интернационални медицински центар, Центар за Радиотерапију, Дванаест беба бб, Бања Лука, Republic of Srpska, Bosnia and Herzegovina
4. Dragoljub Mirjanić, Akademija nauka i umjetnosti Republike Srpske, Bana Lazarevića 1, Banja Luka, Republic of Srpska, Bosnia and Herzegovina

In a transverse computed tomography (CT) image, each pixel corresponds to a specific shade of gray scale or а CT number expressed in Hounsfield units (HU). The CT image is actually а distribution of linear attenuation coefficients (LACμ) in the plane after reconstruction. HU values (normalized to water) in each pixel are defined as: HU(CTnumber) )=tissue-water/water1000. It is known that LAC directly depends on the relative electron density (REDnormalized on water), the atomic number (Z) of the attenuation material and the quality (energy) of the photon beam (80 to 140 kVp at CT) obtained from the CT scanner. HU values, for the human body, are in the range from 79 for lungs (RED is .2),  for water (RED is 1), to 85 for dense bone (RED is 1.456), at X-ray tube voltage of 120 KV. There are several phantoms on the market that allow precise correlation of HU with RED for different tissues. The body of the phantom is usually made of „plastic water“ with several alternating positions in which plugs (cylinders) of known RED and mass density can be placed. The CT conversion curve (HU  f (RED)), i.e. the conversion of the obtained HU into known values of RED or tissue density, allows us to determine with great reliability which type of tissue it is and whether it is a tumor or healthy tissue.

Кључне речи: computed tomography; Hounsfield units; relative electron density; conversion curve.

Тематска област: СИМПОЗИЈУМ Б - Биоматеријали и наномедицина

Датум: 06.07.2021.

Contemporary Materials 2021 - Savremeni Materijali


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