![]() ![]() 4,5,7–9 Several research groups are investigating different techniques to improve calculation times for patient-specific Monte Carlo dose estimation 10,11 such efforts may provide real-time Monte Carlo based patient dosimetry in the future. The use of Monte Carlo may provide the closest estimate for individualized patient dosimetry, and is generally considered the gold standard among the different dosimetry techniques. Currently, there are two approaches for estimating patient organ dose in CT: first, an empirical dose measurement using physical anthropomorphic phantoms in conjunction with any number of dosimeter options, one example of which is the use of metal oxide semiconductor field effect transistors (MOSFETs), 2,3 and second, software dose calculations using computational Monte Carlo phantoms. The use of volume computed tomography (CT) dose index (CTDI vol) and dose length product (DLP) has long been understood to be inappropriate for patient dosimetry in CT (Ref. Calculated patient organ dose, using patient SSDE and CF SSDE organ, was compared to previously published pediatric patient doses that accounted for patient size in their dose calculation, and was found to agree in the chest to better than an average of 5% (27.6/26.2) and in the abdominopelvic region to better than 2% (73.4/75.0). A means to estimate patient organ dose was demonstrated. ![]() For organ/tissue that extended beyond the scan volume (i.e., skin, bone marrow, and bone surface), correlation was determined to be poor (average 0.3 range: 0.1–0.4) for both the chest and abdominopelvic regions, respectively. For organs fully covered by the scan volume, correlation in the chest (average 1.1 range 0.7–1.4) and abdominopelvic region (average 0.9 range 0.7–1.3) was near unity. Individual CF SSDE organ were determined for a total of 23 organs in the chest and abdominopelvic region across nine weight subcategories. Phantom effective diameters were matched with patient population effective diameters to within 4 cm thus, showing appropriate scalability of the phantoms across the entire pediatric population in this study. ![]()
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