Click here to


Are you sure ?

Yes, do it No, cancel

A Novel Compensator for Compensator Based IMRT Device for Low- and Middle- Income Countries

B Sengupta*, K Oh, E Ford, University of Washington, Seattle, WA


(Sunday, 7/12/2020)   [Eastern Time (GMT-4)]

Room: AAPM ePoster Library

Purpose: major cause for the limited access to RT in low- and middle income countries is the high cost for installing and running a RT device and the infrastructure support that it requires. Our goal is to develop a novel compensator based IMRT device which will be more cost effective and reliable than the current RT devices used in low- and middle-income countries.

Methods: device consists of a Co-60 source and iIntensity modulation is provided by a compensator system with automatic exchange between fields. An existing TPS (RayStation v. 8b) is used to create patient-specific compensators using the fluence maps and creating the thickness map of the compensator. These maps are then adjusted for the divergence of the beam to create the compensator which is written out to files in a format that is compatible with the TPS. The plan is then verified on the TPS with the compensator. For treatment, the compensator shape is 3D printed and filled with reusable tungsten beads. Monte Carlo Simulations using the Geant4 toolkit were performed to establish data in support of the diverging compensator.

Results: this method in the compensator is represented as a region-of-interest (ROI) in the TPS overridden with the known density of material. Triangular mesh constructs (.stl files) were developed to describe the compensator shape which is divergent with the beam. These are used as input in both in Geant4 and the TPS. Monte Carlo simulations verify the treatment field produced by the compensator and was able to reproduce and extend results in literature. Validation of treatment plans for 25 H&N cancer patients is underway and will be presented.

Conclusion: system combines 3D printing and reusable compensating material to provide IMRT delivery that meets the current the safety standards while keeping the treatment times and costs low.


Not Applicable / None Entered.


TH- External Beam- Photons: Development (new technology and techniques)

Contact Email