International Journal of Radiation Research, January 2018 Volume 16, No 1 Assessment of radiation-induced cancer risk to patients undergoing computed tomography angiography scans INTRODUCTION Computed tomography angiography (CTA) is a suitable imaging technique to evaluate the blood vessels. The CTA scans are applied for diagnosis of blood vessels diseases in different body parts such as the heart, chest, head, neck, abdomen, pelvis, and upper and lower extremities. As the result of rapid technological evolution especially in multidetector-row CT (MDCT) scanners, the clinical indications for CTA have markedly increased in the last several years. However, one major disadvantage of CT is the potential risk of cancer related to ionizing radiation exposure during the procedures. It was estimated that about 2% of cancers in the United States were attributable to CT scans (1) . For assessing the potential bene.it-risk ratio of various CTA scans, the referring physicians, cardiologists and radiologists need to have some knowledge about the magnitude of the radiation risk associated with these procedures. The American College of Radiology (2) has also highlighted this subject. There were some studies that measured effective dose for CTA of brain (3-6) , the lower extremities (7) , and studies that investigated protocols for reduction of the radiation dose in CTA of carotid (8) , abdomen (9) , A. Chaparian 1* and H. Karimi Zarchi 2 1 Technology of Radiology Department, Isfahan University of Medical Sciences, Isfahan, Iran 2 Department of Medical Physics, Shahid Sadoughi University of Medical Sciences, Yazd, Iran ABSTRACT Background: Computed tomography angiography (CTA) scan is a suitable imaging technique to evaluate the blood vessels. However, one major disadvantage is the potenal risk of cancer related to ionizing radiaon exposure during the procedures. The aim of this invesgaon was to esmate the risk of exposure induced cancer death (REID) values for some common computed tomography angiography (CTA) scans. Materials and Methods: The scan parameters and paent gender and age were collected for a total of 251 paents undergoing CTA scans of the head (51), carod (50), abdomen (50), thoracic (50) and the lower extremies (50). The effecve diameter, scan length, effecve tube current and the dose-length product (DLP) values were obtained for each paent. The organ doses and the effecve dose were calculated by the ImpactDose program. The REID values were esmated for the different CTA scans by the calculated organ doses and corresponding age- and sex- specific risk factors. Results: The REID values for the CTA scans of head were 17±4 and 20±3 per million, carod were 35±9 and 67±14 per million, the lower extremies were 60±26 and 64±24 per million, thoracic were 97±28 and 204±72 per million, and for abdomen were 101±25 and 194±72 per million, for males and females, respecvely. Conclusion: The results of this invesgaon showed that CTA scans are associated with non-negligible risk of exposure induced cancer. A variaon in radiaon cancer risk as a funcon of age and gender of the paents was demonstrated and found that the younger female paents were at the highest risk. Keywords: Computed tomography angiography, risk of exposure induced cancer death, Monte Carlo simulations. *Corresponding authors: Dr. Ali Chaparian, Fax: +98 3137929000 E-mail: ali_chaparian@yahoo.com Revised: February 2017 Accepted: March 2017 Int. J. Radiat. Res., January 2018; 16(1): 107-115 ► Original article DOI: 10.18869/acadpub.ijrr.16.1.107 Downloaded from ijrr.com at 20:05 +0330 on Friday March 9th 2018