Page 78 - ARNM-2-3

Advances in Radiotherapy &

Nuclear Medicine

ORIGINAL RESEARCH ARTICLE
Multislit gamma camera for external beam

radiotherapy assistance: Experimental proof of
concept

2
1
Hugo Simões * , Luís Lopes 1 , Paulo J. B. M. Rachinhas , and Paulo Crespo 1,3
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

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
*Corresponding author: monitoring. In this study, a multi-slice OrthoCT detector prototype was developed
Hugo Simões and tested under in-beam irradiation. The system utilizes gadolinium orthosilicate
(hugo.simoes@coimbra.lip.pt)
scintillator crystals coupled to photomultiplier tubes and a collimator made of
Citation: Simões H, Lopes L, lead slices. Experimental measurements were conducted using a heterogeneous
Rachinhas PJBM, Crespo P.
Multislit gamma camera for phantom made of acrylic with an air cavity inside. The phantom was irradiated with
external beam radiotherapy a TrueBeam linac operating at 6 MV in the flattening-filter-free mode. The findings
assistance: Experimental proof of of this study indicate that this innovative imaging technique is capable of providing
concept. Adv Radiother Nucl Med. morphological images of the phantom. This accomplishment is achieved without the
2024;2(3):4099.
doi: 10.36922/arnm.4099 need to rotate the X-ray source around the object to be irradiated, demonstrating the
feasibility of such a system.
Received: July 1, 2024
Accepted: August 23, 2024
Keywords: Orthogonal computed tomography; Low-dose imaging for radiotherapy;
Published Online: September 24,
2024 Rotation-free megavoltage tomography; X-ray detection; Image-guided radiotherapy
Copyright: © 2024 Author(s).
This is an Open-Access article
distributed under the terms of the
Creative Commons Attribution 1. Introduction
License, permitting distribution,
and reproduction in any medium, External beam radiotherapy is one of the primary modalities prescribed for cancer
provided the original work is treatments. The most recently developed techniques allow for more conformal
properly cited. treatments, which are directly correlated with the therapeutic outcome. However,
1
Publisher’s Note: AccScience this increase in dose conformality requires an even more precise positioning of the
Publishing remains neutral with patient and knowledge of their anatomy and morphology at the moment of irradiation
regard to jurisdictional claims in
published maps and institutional so that underdosage of tumor or overdosage of the surrounding healthy tissues can
affiliations be minimized. Examples of factors that may compromise this treatment conformality

Volume 2 Issue 3 (2024) 1 doi: 10.36922/arnm.4099