AccScience Publishing / ARNM / Online First / DOI: 10.36922/arnm.4099
ORIGINAL RESEARCH ARTICLE

Multislit gamma camera for external beam radiotherapy assistance: Experimental proof of concept

Hugo Simões1* Luís Lopes1 Paulo J. B. M. Rachinhas2 Paulo Crespo1,3
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1 Laboratory of Instrumentation and Experimental Particle Physics, Rua Larga, Coimbra, Portugal
2 Department of Radiotherapy, Coimbra Hospital and University Center, Praceta Mota Pinto, Coimbra, Portugal
3 Department of Physics, Faculty of Science and Technology, University of Coimbra, Rua Larga, Coimbra, Portugal
Submitted: 1 July 2024 | Accepted: 23 August 2024 | Published: 24 September 2024
© 2024 by the Author (s). This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution 4.0 International License ( https://creativecommons.org/licenses/by/4.0/ )
Abstract

The orthogonal computed tomography (OrthoCT) concept, based on orthogonal ray imaging, is a low-dose imaging technique currently under investigation to potentially aid in external-beam radiation therapy treatments. This technique involves detecting radiation scattered within the patient and emitted at approximately 90° from the direction of the incoming beam. This scattered radiation can be collected by a 1D-detector system with a multisliced collimator positioned perpendicular to the incident beam axis. Such a system holds promise for on-board imaging with the patient positioned and prepared for treatment, as well as for real-time treatment monitoring. In this study, a multi-slice OrthoCT detector prototype was developed and tested under in-beam irradiation. The system utilizes gadolinium orthosilicate scintillator crystals coupled to photomultiplier tubes and a collimator made of lead slices. Experimental measurements were conducted using a heterogeneous phantom made of acrylic with an air cavity inside. The phantom was irradiated with a TrueBeam linac operating at 6 MV in the flattening-filter-free mode. The findings of this study indicate that this innovative imaging technique is capable of providing morphological images of the phantom. This accomplishment is achieved without the need to rotate the X-ray source around the object to be irradiated, demonstrating the feasibility of such a system.

Keywords
Orthogonal computed tomography
Low-dose imaging for radiotherapy
Rotation-free megavoltage tomography
X-ray detection
Image-guided radiotherapy
Funding
This study was partly funded by Project POCI-01-0145- FEDER-0073334, supported through FCT/MCTES national funds and FEDER, in accordance with Parceria PT2020 LIP - FIS/50007.
Conflict of interest
The authors declare that they have no competing interests.
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Advances in Radiotherapy & Nuclear Medicine, Electronic ISSN: 2972-4392 Published by AccScience Publishing