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Program Information

Monte Carlo Treatment Planning for a New Co-60 Total Body Irradiator

M Snyder

M Snyder1,2*, R Halford2 , J Burmeister1,2 , B Loughery2 , A Nalichowski2 , T Bossenberger2 , G Baran2 , J Rakowski 1,2 K Masi2 , (1) Wayne State University, Detroit, MI, (2) Karmanos Cancer Institute, Detroit, MI


SU-I-GPD-T-392 (Sunday, July 30, 2017) 3:00 PM - 6:00 PM Room: Exhibit Hall

Purpose: To develop a method for calculating volumetric TBI dose.

Methods: A new Co-60 TBI irradiator has been installed at our center. Treatments are done with single AP and PA fields at SSDs of ~220 cm. To calculate volumetric dose a process was created using the Eclipse TPS for virtual simulation, the BEAMnrc and DOSXYZnrc Monte Carlo codes for dose calculation, and 3D printing for lung block creation.

Results: The process begins with a two-stage CT study—necessary in order to image the entire length of the patient. The two scans are stitched together into one image set and imported into Eclipse. Within Eclipse a single field is placed representing an extended SSD TBI field, and lung blocks are drawn as required. The plan and image information is exported to a MATLAB GUI where beam axis and block information is parsed and image information is used to create input files for both a BEAMnrc TBI head model and the resulting DOSXYZnrc dose calculation. The calculation is performed over the course of ~12 hours resulting in a statistical uncertainty of < 1% for the high dose regions. The dose information is written out in DICOM format and imported into Eclipse for evaluation. Block information from the original plan is used to create .STL files for 3D printing of block molds in lieu of traditional foam-cut molds due to the large SSDs and off axis position of lung blocks.

Conclusion: The process allows the calculation of accurate volumetric dose in TBI treatments in a clinically reasonable timescale. The ability to evaluate volumetric dose in the normal tissues—particularly in the lungs—will allow for more accurate evaluation of dose-toxicity relationships.

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