Date(s) - 10/07/2013
Computed tomography contributions to public radiation exposure have increased with increasing examination prevalence and patient throughput. Organ dose has been suggested as the best metric for quantifying risks associated with computed tomography exposures for its duality in predicting both deterministic and stochastic effects.
A Monte Carlo based software program providing prospective organ dose estimates from computed tomography examinations has been developed at the University of Florida. The program’s ability to account for tube current modulation and accurately report organ doses can be validated through experimental measurements. The goal of this work was to provide organ dose estimates from exposures delivered by a Toshiba Aquilion ONE computed tomography scanner using optically stimulated luminescent dosimeters within anthropomorphic phantoms.
A total of 14 chest abdomen pelvis examinations were conducted for 3 anthropomorphic phantoms: a reference 10-year-old hermaphrodite, 15-year-old female, and adult male with 49, 46, and 57 point measurement locations, respectively. Point doses were averaged across each organ to provide average organ doses for 15 organs (16 for the adult male with the addition of the prostate). With the implementation of tube current modulation, the most significant dose reduction was observed within the thyroid: 1.97% to 43.92%. In contrast, minimal dose reduction was observed within the small intestine, colon, and liver: percent changes ranging from +10.26% to -8.00%, +6.76% to -9.61, and +3.77% to -10.00%, respectively. Reported organ doses closely resemble values presented in Lindsay Sinclair’s dissertation work from measurements made within cadaveric subjects utilizing the same dosimetry system and scanner.