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CAPULET: A Novel Coded Aperture Prompt-Gamma Ultra-Light Imaging DETector

A Vella*, F Van den Heuvel, CRUK/MRC Oxford Institute for Radiation Oncology, University of Oxford, Oxford, GB


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

Room: AAPM ePoster Library

To design and characterise CAPULET, a novel Prompt–gamma Ultra-Light imaging dETector for particle beam range verification, by Monte Carlo simulations. The model consists of Coded Aperture (CA) masks and an energy–dispersive pixelated semiconductor (EDPS) imaging detector.

CAPULET uses a 7x7 mosaicked Modified Uniformly Redundant Array (MURA) CA mask, and 20x20x10mm EDPS detector placed behind the mask. The detector can simultaneously capture energy-spectra and images of photon emissions. A 150MeV proton beam generates a prompt gamma (PG) energy-spectrum within a cylindrical PMMA phantom. CAPULET is placed perpendicular to the beam, alongside the phantom. Images with 60mm CA thickness were compared to a 10mm wide 60mm thick slit (optimum width/thickness (Vella, ESTRO 2020)), and the Proton Range (PR) was calculated. CAPULET is also exposed to a PG point source to optimise image quality. CA thicknesses 40 to 60mm were explored and Signal-to-Noise Ratio’s (SNR) compared with the slit.

From the energy-spectra, CAPULET detects three-times more PGs than the slit. PR is estimated from the pixelated images, CAPULET=157.97mm and slit=159.53mm (~0.3 and ~2mm difference to the nominal PR, respectively). CAPULET with a 40mm CA mask exposed to PG point source is superior to a 40mm thick slit by 5% and appears equivalent to 60mm thick slit (2% difference). CAPULET SNR is higher compared to slit at low thicknesses, this drops for thicknesses up to 60mm.

CAPULET is a fast, compact and light imaging system, addresses the limitations of the PG slit camera in terms of field-of-view (due to the slit), and bulkiness (due to scintillators and collimator thickness). The detector provides energy–dispersive and imaging capabilities for particle beam range verification, it is faster (three-times more PGs thanks to CA masks), lighter (higher SNR ratio with a 40mm mask), compact (EDPS detector 10mm thick against bulky scintillators) for gantry/couch mounting.

Funding Support, Disclosures, and Conflict of Interest: AV is supported by a Cancer Research UK Grant: ArtNET: Number C309/A21993. FVdH: is supported by a Cancer Centre grant CRUK C2195/A25014 and CRUK OIRO Number C5255/A23755.


Monte Carlo, Capture Gamma Rays, Radiation Detectors


IM- Particle (e.g., Proton) CT: Development (New technology and techniques)

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