Computational model for detector timing effects in Compton-camera based prompt-gamma imaging for proton radiotherapy.

Computational model for detector timing effects in Compton-camera based prompt-gamma imaging for proton radiotherapy.
Phys Med Biol. 2020 Apr 22;:
Authors: Maggi P, Peterson SW, Panthi R, Mackin DS, Yang H, He Z, Beddar S, Polf J
Abstract
This paper describes a realistic simulation of a Compton-camera (CC) based prompt-gamma (PG) imaging system for proton range verification for a range of clinical dose rates, and its comparison to PG measured data with a pre-clinical CC. We used a Monte Carlo plus Detector Effects (MCDE) model to simulate the production of prompt gamma-rays (PG) and their energy depositions in the CC. With Monte Carlo, we simulated PG emission resulting from irradiation of a high density polyethylene phantom with a 150 MeV proton pencil beam at dose rates of 5.0×108, 2.6×109, and 4.6×109 p+/s. Realistic detector timing effects (e.g. delayed triggering time, event-coincidence, dead time, etc,) were added in post-processing to allow for flexible count rate variations. We acquired PG emission measurements with our pre-clinical CC during irradiation with a clinical 150 MeV proton pencil beam at the same dose rates. For simulations and measurements, three primary changes could be seen in the PG emission data as the dose rate increased: 1) reduction in the total number of detected events due to increased dead-time percentage; 2) increase in false-coincidence events (i.e. multiple PGs interacting, rather than a single PG...

Source: Physics in Medicine and Biology - April 21, 2020 Category: Physics Authors: Maggi P, Peterson SW, Panthi R, Mackin DS, Yang H, He Z, Beddar S, Polf J Tags: Phys Med Biol Source Type: research