Evaluation of organ doses and specific k effective dose of 64-slice CT thorax examination using an adult anthropomorphic phantom

Abstract

The magnitude of radiation dose in computed tomography (CT) depends on the scan acquisition parameters, investigated herein using an anthropomorphic phantom (RANDO®) and thermoluminescence dosimeters (TLD). Specific interest was in the organ doses resulting from CT thorax examination, the specific k coefficient for effective dose estimation for particular protocols also being determined. For measurement of doses representing five main organs (thyroid, lung, liver, esophagus and skin), TLD-100 (LiF:Mg, Ti) were inserted into selected holes in a phantom slab. Five CT thorax protocols were investigated, one routine (R1) and four that were modified protocols (R2 to R5). Organ doses were ranked from greatest to least, found to lie in the order: thyroid>skin>lung>liver>breast. The greatest dose, for thyroid at 25 mGy, was that in use of R1 while the lowest, at 8.8 mGy, was in breast tissue using R3. Effective dose (E) was estimated using three standard methods: the International Commission on Radiological Protection (ICRP)-103 recommendation (E103), the computational phantom CT-EXPO (E(CTEXPO)) method, and the dose-length product (DLP) based approach. E103 k factors were constant for all protocols, ~8% less than that of the universal k factor. Due to inconsistency in tube potential and pitch factor the k factors from CTEXPO were found to vary between 0.015 and 0.010 for protocols R3 and R5. With considerable variation between scan acquisition parameters and organ doses, optimization of practice is necessary in order to reduce patient organ dose.

A comparison study of radiation effective dose in ECG-Gated Coronary CT Angiography and calcium scoring examinations performed with a dual-source CT scanner

“…The E/DLP value of 0.026 mSvmGy −1 cm −1 used to calculate the estimated effective dose was obtained based on the International Commission on Radiological Protection (ICRP) report 15 . The value was more accurate for estimating cardiac CT radiation dose compared with chest CT examination 3 , 29 . The cardiac region had been reported to be more radiosensitive than the chest and the tissue weighting factor was changed significantly from 0.05 to 0.12 for breast as reported in ICRP-103 32 .…”

“…The scanning range for post-CABG patients started from the arch of the aorta until the heart apex to include the ligation of the coronary artery bypass 3 . As part of the optimization process, the radiation dose from CT scans could be reduced with a few techniques, such as using an iterative reconstruction algorithm, increasing the helical pitch and lowering the tube potential energy 27 – 29 . Therefore, lowering the tube voltage to reduce effective radiation dose was practical for small- and average-sized patients, but not for those with large habitus 15 , 30 .…”

Feasibility of customizing titanium implant with three-dimensional CT imaging of low dose in skull

“…The comparison of radiation doses of different scanning schemes is mainly through comparing volume CT dose index (CTDIvol), dose length product (DLP) and effective dose (ED). [ 8 – 13 ] CTDIvol is automatically calculated and recorded by equipment according to scanning technology (tube voltage, tube current and pitch, etc.). Generally the higher the dose, the more serious the biological effect and the greater the damage to the body.…”

“…[ 11 – 12 ] ED is an indicator that commonly understood as the amount of radiation received by patients undergoing a numerous type of radiological examinations which is significantly practical and provides meaningful information to many respective researchers. [ 13 ]…”

Evaluation of Organ Dose and Image Quality Metrics of Pediatric CT Chest-Abdomen-Pelvis (CAP) Examination: An Anthropomorphic Phantom Study

“…Generally, the radiation-absorbed dose can be measured by inserting a passive dosimeter inside anthropomorphic phantom as it is the accurate way to measure the radiation absorbed by radiosensitive organs or tissues of patients [13][14][15]. Likewise, Monte Carlo estimation on computational phantom, such as CT-Expo (Version 2.3.1, Hannover, Germany), is able to estimate an organ-absorbed dose and effective dose based on the subject's age and gender [16][17][18].…”