Patient-specific organ dose calculated by dose tracking software based on monte carlo simulation in pediatric abdominal CT

Abstract

This study aimed to determine the patient-specific organ doses using Radimetrics dose tracking software in pediatric abdominal CT at Praram9 Hospital. The organ doses were measured using the anthropomorphic Rando phantom inserted with radiophotoluminescent glass dosimeters (RPLGDs) to verify the organ doses calculated by Radimetrics program. The retrospective data were collected from pediatric abdominal CT 164 studies (78 patients), age range 0-15 years-old), who underwent single phase abdominal CT at Praram9 Hospital. The tube voltages ranged between 80 and 135 kVp were adjusted according to the size and age of patients, and rotation time 0.35-0.5 sec. All patients were acquired using the automatic exposure control (AEC) protocol. The organ and effective doses (ED) calculations were calculated based on the Monte Carlo simulation internally determined by Radimetrics in accordance with patient age derived from stylized computational phantom models. The size-specific dose estimates (SSDE) were calculated based on the effective diameter method. The %difference of the organ doses compared between glass dosimeters and Radimetrics ranged from 8.88-51.58%. Five highest average organ doses were found in kidneys, stomach, urinary bladder, upper large intestine, and spleen for 15-yrs patients, with the values of 18.44, 17.07, 16.74, 16.47 and 16.14 mGy, respectively. The average ED for abdominal CT in newborn, 1, 5, 10 and 15-yrs were 2.24, 3.23, 4.05, 4.46 and 8.46 mSv, respectively. Average SSDE were 2.72, 4.52, 6.15, 2.28 and 14.21 mGy, respectively. In conclusion, patient-specific organ, and effective doses from 0 through 15-years-old can be determined effectively using dose tracking software. As the various sizes of pediatric patients, the patient ED and SSDE were correlated with patient’s body weight rather than the patient age.