Work

Technical Note: Time‐gating to medical linear accelerator pulses: Stray radiation detector

Year: 2018

Type: article

Abstract: PURPOSE: CCD cameras are employed to image scintillation and Cherenkov radiation in external beam radiotherapy. This is achieved by gating the camera to the linear accelerator (Linac) output. A direct output signal line from the linac is not always accessible and even in cases where such a signal is accessible, a physical wire connected to the output port can potentially alter Linac performance through electrical feedback. A scintillating detector for stray radiation inside the Linac room was developed to remotely time-gate to linac pulses for camera-based dosimetry. METHODS: A scintillator coupled silicon photomultiplier detector was optimized and systematically tested for location sensitivity and for use with both x rays and electron beams, at different energies and field sizes. Cherenkov radiation emitted due to static photon beams was captured using the remote trigger and compared to the images captured using a wired trigger. The issue of false-positive event detection, due to additional neutron activated products with high energy beams, was addressed. RESULTS: (BGO) crystal. With a larger scintillator size, the detector could be placed even beyond 3 m distance. False-positive triggering was reduced by a coincidence detection scheme. Negligible fluctuations were observed in time-gated imaging of Cherenkov intensity emitted from a water phantom, when comparing directly connected vs this remote triggering approach. CONCLUSION: The remote detector provides untethered synchronization to linac pulses. It is especially useful for remote Cherenkov imaging or remote scintillator dosimetry imaging during radiotherapeutic procedures when a direct line signal is not accessible.

Source: Medical Physics

DOI: 10.1002/mp.13311

Authors: Muhammad Ramish Ashraf, Petr Bruza, Venkat Krishnaswamy, David J. Gladstone, Brian W. Pogue

Institutions: Dartmouth College, DoseOptics (United States), Dartmouth–Hitchcock Medical Center, Dartmouth Cancer Center

Language: English

Topic: Advanced Radiotherapy Techniques

Subfield: Radiation

Field: Physics and Astronomy

Domain: Physical Sciences

Open Access status: green

Funders: National Institutes of Health, National Cancer Institute, National Institute of Biomedical Imaging and Bioengineering