Abstract:
Computed Tomography Angiography (CTA) and Digital Subtraction Angiography (DSA) are the types of cerebrovascular disorders examination. The 64-row multidetector CTA (64-MDCTA) provides vascular image quality of the brain similar to the DSA, but the effective dose of CTA is 1/5 lower than DSA studied in phantom. The purpose of this study was to evaluate patient effective dose from 64-MDCTA and DSA examination. In this study, the effective dose according to ICRP 103 received by 30 patients (15 male, 15 female, mean age 49 yrs, range 23-89 yrs, mean BMI 24 kg/m2) underwent CTA examination of the brain were determined by the Dose Length Product (DLP) values in the unit of mGy.cm from a 64-row MDCT (Somatom Definition AS; Siemens, Erlangen, Germany) multiplied by the k-factor of 0.0019 mSv/mGy.cm. The effective dose from 30 patients (14 male and 16 female, mean age 47 yrs, range 24-81 yrs, mean BMI 23 kg/m2) from diagnostic cerebral DSA procedure calculated by using Dose Area Product (DAP) values displayed from DAP meter attached in a biplane angiography equipment (Axiom Artis; Siemens, Erlangen, Germany) multiplied by dose conversion coefficient of 0.087 mSv/mGy.cm2. For CTA, the mean effective dose was 3.70 (2.82- 5.19) mSv. The effective dose of CTA depends on patient characteristics (weight, height, and BMI), exposure technique (mAs and kVp) and scan length when fixing other parameters (slice collimation, slice acquisition, pitch, and tube rotation time). In DSA procedure, the mean effective dose was 5.94 (3.30-10.06) mSv. A number of 2D radiography and a number of 3-Dimentional rotational angiography were the key factors affecting the effective dose. The number of vessels selective catheterization and fluoroscopic time were moderate affects the effective dose. The experience of radiologist was no significant correlation with the effective dose. The mean effective dose from DSA procedure was 1.5 time of CTA examination of the brain.
