Dosimetric Evaluation for Eye Lens and Thyroid Gland from Brain Computed Tomography Scan
Date
2022
Authors
Haya Jamal Alruzieh
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Abstract
Brain Computed Tomography scan is one of the most frequent examinations in the
last years. This study was aim to estimate the effective dose (ED) and the organ doses from
brain computed tomography (CT) scan, and cancer probability was for the thyroid gland.
The manual calculation and commercially available Monte Carlo-based software
VirtualDoseTM CT were used to achieve the objective of this study. A total of 80 adult
patients from both genders were selected randomly from the Thabet-Thabet hospital.
Helical and axial scan modes were applied. Demographic data for patients, scanning
parameters, and dose indicators that involve the x-ray tube kilovoltage (kVp), milliamperesecond (mAs), dose length product (DLP), computed tomography dose index volume
(CTDIvol) were recorded.
The average value of EDDLP is 1.8 mSv compared to EDVirtual with an average value
of 5.0 mSv for the helical scan. In an axial scan, the average value of EDDLP is 2.4 mSv
compared to EDVirtual with an average value of 4.1 mSv. For Helical Scan, the highest
calculated ED value was 2.1 mSv, belonging to females aged 82 years. For Axial Scan, the
highest calculated ED value was 2.9 mSv, belonging to females aged 55 years old.
Based on virtual software, in the helical scan mode, the highest value is 6.5 mSv,
belonging to a female who is 81 years old. On the other hand, in the axial scan, the highest
value was 8.3 mSv belonging to a female who is 55 years old.XV
The average values of organ doses in the whole population were 43.1 and 19.7 mGy
for the thyroid gland and eye lens, respectively in helical Scan. While axial scan was 9.1
mGy for thyroid, and 32.1mGy for eye lens. The highest value in thyroid cancer risk
assessment is 2.3×106 found in 2 females who are 20, 68 years old in the helical scan. Also,
for the axial scan, the highest value is 2.7×106 belonging to a female who is 55 years old.
Generally, the calculated radiation doses from the brain CT exams in this study are minimal
and similar to those described in other works of literature, however, the technologist should
choose and adjust protocols to avoid unnecessary radiation to patients and satisfy the as low
as reasonably achievable (ALARA) principle
Description
Keywords
CT, Organ dose, Effective dose, Radiation cancer risk.