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Session: Imaging: Dosimetry in CT/CBCT [Return to Session]

Implementation of Tube Current Modulation for Pediatric and Adult CT Patients with Various Body Sizes Into NCICT2.0

C Lee*, Y Yeom, National Cancer Institute, Rockville, MD


MO-IePD-TRACK 2-4 (Monday, 7/26/2021) 12:30 PM - 1:00 PM [Eastern Time (GMT-4)]

Purpose: To implement a prospective tube current modulation (TCM) feature into an organ dose calculation program for CT patients with various body sizes, NCI dosimetry system for CT (NCICT) 2.0, by using a library of body size-dependent computational human phantoms.

Methods: We created a comprehensive library of TCM profiles for a total of 351 pediatric and adult body size-dependent computational human phantoms. We adopted a generic ray-tracing algorithm (Li et al. PMB 2014) to create TCM profiles: calculation of the attenuation at a given angle within a CT fan beam geometry for the energy spectrum of a reference CT scanner (Siemens Sensation 16). We averaged angular modulation in a single rotation to derive surrogate longitudinal modulation profiles with 1-cm intervals in each phantom. The resulting TCM profiles were implemented into the NCICT2.0 program. We compared organ doses for different scan protocols between fixed tube current and TCM scans.

Results: A comprehensive library of TCM profiles were created from a total of 351 pediatric and adult computational phantoms with various body sizes and implemented into NCICT2.0. When the TCM strength was set 0.5, dose reduction from TCM was clearly observed in low to normal BMI phantoms but organ doses under TCM were greater than those under fixed current for high BMI phantoms. Lung dose for the 60-kg adult male phantom with the height of 175 cm reduced by 51% under TCM but that for the 100-kg phantom at the same height increased by 12% under TCM compared to fixed current scans.

Conclusion: We established a library of generic TCM profiles from a library of body size-dependent computational phantoms and implemented the feature into NCICT2.0. The upgraded program should be useful to estimate organ doses for CT patients undergoing TCM-based CT scans.

Funding Support, Disclosures, and Conflict of Interest: NCICT licensed to PACS Health, LLC.



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