Refined scan protocol for the evaluation of pulmonary perfusion standardized image quality and reduced radiation dose in dynamic chest radiography

Abstract

AbstractPurposeDynamic chest radiography (DCR) is a novel imaging technique used to noninvasively evaluate pulmonary perfusion. However, the standard DCR protocol, which is roughly adapted to the patient's body size, occasionally causes over‐ or underexposure, which could influence clinical evaluation. Therefore, we proposed a refined protocol by increasing the number of patient body mass index (BMI) categories from three to seven groups and verified its usefulness by comparing the image sensitivity indicators (S‐values) and entrance surface doses (ESDs) of the conventional protocol with those of our refined protocol.MethodsThis retrospective observational study included 388 datasets (standing position, 224; supine position, 164) for the conventional protocol (December 2019–April 2021) and 336 datasets (standing position, 233; supine position, 103) for the refined protocol (June–November 2021). The conventional protocol (BMI‐3 protocol) divided the patients into three BMI groups (BMI < 17, 17≤BMI < 25, and BMI ≥ 25 kg/m2), whereas the refined protocol (BMI‐7 protocol) divided the patients into seven BMI groups (BMI < 17, 17 ≤ BMI < 20, 20 ≤ BMI < 23, 23 ≤ BMI < 26, 26 ≤ BMI < 29, 29 ≤ BMI < 32, and BMI ≥ 32 kg/m2). The coefficients of variation (CVs) for the S‐values and ESDs acquired using the two protocols were compared.ResultsThe CVs of the S‐values in the BMI‐7 protocol group were significantly lower than those in the BMI‐3 protocol group for the standing (28.8% vs. 16.7%; p < 0.01) and supine (24.5% vs. 17.7%; p < 0.01) positions. The ESDs of patients scanned using the BMI‐7 protocol were significantly lower than those scanned using the BMI‐3 protocol in the standing (1.3 vs. 1.1 mGy; p < 0.01) and supine positions (2.5 vs. 1.6 mGy; p < 0.01), although the mean BMI of the two groups were similar.ConclusionWe introduced the BMI‐7 protocol and demonstrated its standardized image quality and reduced radiation exposure in patients undergoing DCR.