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A novel technique for peripheral dose measurements in external beam radiation therapy

Published online by Cambridge University Press:  03 March 2022

Gowri Balan
Affiliation:
School of Advanced Sciences, Vellore Institute of Technology, Vellore, India Department of Medical Physics, Govt. Arignar Anna Memorial Cancer Hospital and Research Institute, RCC, Kanchipuram, India
Velayudham Ramasubramanian*
Affiliation:
School of Advanced Sciences, Vellore Institute of Technology, Vellore, India
*
Author for correspondence: Dr. Velayudham Ramasubramanian, Professor, School of Advanced Sciences, Vellore Institute of Technology, Vellore 632014, Tamil Nadu, India. Tel: +919994728148. E-mail: vrsramasubramanian@gmail.com

Abstract

Introduction:

In radiotherapy, the dose delivered outside the field is known as peripheral dose (PD). In this study, we have attempted to develop a dataset using the PD values measured with a two-dimensional array, IMatrixx.

Methods:

The IMatrixx was used to measure the PD up to a distance of 45 cm from the field edge, in a Varian Clinac 2100-C machine. Solid water slabs and water phantom were used to get the required geometry for the PD measurements. The measurements were done for different field sizes, collimator angles, source to surface distance (SSD) and depths. The influence of gantry angles and photon energies on the PD was studied. The surface dose measurements were carried out using thermoluminescent detectors (TLD).

Results:

The dataset shows that the PD increased significantly with field size and depth and its increase was insignificant for collimator rotation and SSD. The influence of gantry angle was less pronounced at dmax than at the surface. The TLD measurements at the surface of patients were in agreement with the IMatrixx measurements.

Conclusions:

The IMatrixx can be used for the generation of PD values and it is less time-consuming, accurate, and commonly available in all radiotherapy departments.

Type
Original Article
Copyright
© The Author(s), 2022. Published by Cambridge University Press

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