Estimation of female radiation doses and breast cancer risk from chest CT examinations
Date
2017-12-09
Authors
Lahham, Adnan
ALMasri, Hussein
Kameel, Saleh
Journal Title
Journal ISSN
Volume Title
Publisher
Oxford University Press
Abstract
Breast organ doses, effective doses and lifetime attributable risk (LAR) of breast cancer from chest CT scans are presented for
200 female patients surveyed from 10 hospitals in the West Bank and Gaza Strip, Palestine. Patient data were collected and
organized in a database from May to November 2016. Data include age (15–80 years), weight, height, and calculated body mass
index. Exposure data were also recorded for every examination. Exposure data includes milliampere-second (mAs), X-ray tube
kilovoltage (kVp), computed tomography dose index, dose length product, manufacturer, name and type of operated CT scanner.
Organ and effective doses were evaluated using a web-based commercially available Monte Carlo software: VirtualDose™CT, a
product of Virtual Phantoms, Inc. The software utilizes male and female tissue equivalent phantoms of all ages and sizes including
pregnant patients. The corresponding phantom was selected for every patient according to patient’s tomographic parameters.
Calculated organ doses were used to estimate the LAR of breast cancer according to BEIR VII Phase 2 report. It was found that
radiation doses resulting from the same exam vary widely between different hospitals, depending on the parameters used and the
type of scanner. For all patients, the breast organ dose ranged from 6.5 to 28 mGy per examination, with an average breast organ
dose of 15mGy. The effective dose from chest CT scan per examination ranged from 3 to 14.7 mSv with an average of 7mSv.
For younger females (15–29 years), the LAR of breast cancer risk was estimated to be around 0.05%. For older female patients
(60–79 years), the risk was ~0.001%. It was found that LAR decreases remarkably with patient’s age. Values obtained in this
study vary between hospitals, they are generally low and consistent with other studies reported worldwide.