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Voxel-By-Voxel Dose Prescription Map Based On MRI ADC for Radiation Therapy of Pancreatic Cancer

X Chen

X Chen*, E Ahunbay , X Li , Medical College of Wisconsin, Milwaukee, WI


TU-C1-GePD-J(B)-1 (Tuesday, August 1, 2017) 9:30 AM - 10:00 AM Room: Joint Imaging-Therapy ePoster Lounge - B

Purpose: Previous studies have shown that, the tumor cell density is correlated to the ADC value obtained from diffusion-weighted MRI (DW-MRI), and the pathological tumor grade can be inversely correlated with ADC value in pancreatic adenocarcinoma. The purpose of the study is to propose a method to generate a patient-specified, voxel-by-voxel dose prescription map for pancreatic RT based on the MRI ADC map.

Methods: A Poisson TCP model with the relationship of tumor cell density and ADC estimated for prostate cancer was used. The radiobiological parameters, α and β for the cutoff ADC value of different tumor grade were estimated with the previously reported values for cell lines Capan-2 and Panc-1. The TCP required for a voxel was calculated from the total TCP of the whole tumor volume, and then converted to the required prescription dose for the voxel. A Matlab code was developed to convert the patient specified target ADC map into dose prescription map.

Results: For a selected patient, the tumor target volume is measured as 33.5 cm³ with G2/G1 volume 4.0 cm³ and G3 volume 28.8 cm³. For the dose prescription map to achieve 99.9% of TCP in the whole target volume, the prescription dose will be 58.6 Gy in 28 fractions for each voxel in G1/G2 region and 71.5 Gy for the voxel in G3 region.

Conclusion: A method to create the voxel-by-voxel patient-specified dose prescriptions map for pancreatic cancer based on ADC distribution was developed. The use of such voxel-based prescription dose map would allow safe dose escalation to tumor and/or improve OAR sparing.

Funding Support, Disclosures, and Conflict of Interest: Partially supported by Elekta AB, Stockholm, Sweden.

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