Establishing Local Diagnostic Reference Levels for CT Angiography Examinations

Abstract

Objective: Computed tomography angiography (CTA) examinations are performed to diagnose blood vessel anomalies. However, this examination results in a significant radiation dose being received by the patient. Local diagnostic reference levels (DRLs) are necessary for determining the extent of radiation dose during examinations. Therefore, the main objective of this study is to establish local DRL values for CTA examinations.Material and Methods: In this study, a total of 213 participants underwent CTA examination; wherein: 67 underwent computed tomography (CT) cerebral angiography (CTCA), 80 underwent CT pulmonary angiography (CTPA), 40 underwent CT lower limb angiography with aortogram (CTLLA), and 26 underwent CT upper limb angiography (CTULA). Body mass index along with the circumference of the body were calculated. A number of dose descriptors; such as computed tomography dose index volume (CTDIvol) and dose length product (DLP), were collected, and DLP was used to calculate the effective dose, using the conversion factor.Results: For the angiography phase, CTCA, CTPA, CTLLA, and CTULA had median CTDIvol values of: 31.62, 6.38, 12.16, and 10.12 mGy, respectively. Median DLP and effective dose for CTCA were: 1388.64 mGy*cm & 4.30 mSv, CTPA were 243 mGy*cm & 3.41 mSv, CTLLA were 1855.86 mGy*cm & 12.06 mSv, and CTULA were 945.98 mGy*cm & 2.93 mSv, respectively. Conclusion: The estimated local DRLs were lower than the international standard for the angiographic phase; however, the dose exceeded the international standard when the entire examination was considered. This study revealed the need for dose optimization in CTA examinations.