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IROC-Houston's Pediatric TBI Phantom Credentialing Program

A Molineu

A Molineu*, H Mehrens , D Followill , UT MD Anderson Cancer Center, Houston, TX


SU-E-108-5 (Sunday, July 30, 2017) 1:00 PM - 1:55 PM Room: 108

Purpose: The purpose of this work is to describe IROC-Houston’s new pediatric TBI phantom credentialing program to improve comparability in TBI dose reporting.

Methods: IROC-Houston purchased two 10 year old CIRS ATOM Dosimetry Phantoms, Model Number 706. Phantoms are tissue equivalent and include bone and lung equivalent materials. The phantoms were purchased in two pieces (head and body) and without pre-drilled dosimeter holes. Removable arms were designed and machined in-house using HI-polystyrene. Holes were drilled and rods were created to locate double-loaded TLD capsules in 13 locations: brain, neck, 3 locations in each lung, mediastinum, umbilicus, right and left abdomen and pelvis. The phantom is mailed to institutions participating in NCI sponsored pediatric TBI protocols and can be irradiated with AP/PA or opposed lateral beams in standing, lying down, or modified decubitus positions.

Results: Institutions receiving a phantom are being asked to deliver 300 cGy to the umbilicus using the setup that they would use for a pediatric TBI patient. Institutions that typically treat a percentage of fractions using lung blocks are also asked to irradiate the phantom once without the blocks and a second time with the lung blocks. Replacement TLD for the two irradiations are included in the shipment. Initial irradiations of the phantoms show institution’s dose delivery to the umbilicus is within 2% of the prescription dose. Doses to unblocked points are within 10% of the prescription dose and doses to the blocked lung points range from 22% to 47% of the prescription dose.

Conclusion: The TBI phantoms will be used for credentialing purposes to assess the accuracy of an institution’s TBI dose calculation, comparability of reported TBI doses between institutions and to give an indication of what dose the lungs are receiving for TBI patients accrued in NCI sponsored trials.

Funding Support, Disclosures, and Conflict of Interest: This research was funded by NCI grant CA180803.

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