Estimate of organ radiation absorbed doses in clinical CT using the radiation treatment planning system

Organ absorbed doses in computed tomography (CT) scans can be measured with anatomical phantoms but not inside the human body. In this study, a straightforward method was investigated to estimate organ doses in clinical CT using the radiation treatment planning system (RTPS) and compared them with experimental results of photoluminescence dosemeters (PLD). In a heterogeneous phantom, the average difference between PLD and RTPS values were 25.0 % for the body and 7.1 % for the lung. Using CT data, organ doses in 30 clinical cases were then calculated. There was a significant inverse correlation between the calculated values of organ doses and body mass index (BMI, correlation coefficients (r)520.69 (whole body), 20.80 (right lung), 20.81 (left lung), 20.76 (spinal cord), 20.74 (vertebra bone), 20.74 (heart), and 20.79 (oesophagus), all p < 0.01). An RTPS can be a simple and useful tool for estimating equivalent doses inside the human body, during whole-body CT scans.