<abstract xml:lang="en" xmlns="http://www.w3.org/1999/xhtml"><bold>Introduction.</bold> External photon beam modulation using compensators in order to achieve a desired dose distribution when brachytherapy treatment is followed by external beam radiation is a well-established technique. A compensator modulates the central part of the beam, and the dose beneath the thickest part of the compensator is delivered mostly by scattered, low energy photons. A two-dimensional detector with a good spatial resolution is needed for the verification of those beams. In this work, the influence of different types of detectors on the measured modulated dose distributions was examined.<bold>Materials and methods.</bold> Dosimetric verification was performed using X-Omat V, Eastman Kodak radiographic films at different depths in a solid water phantom. The film measurements were compared with those made by ionization chambers. Photon beams were also modelled using EGSnrc Monte Carlo algorithm to explain the measured results.<bold>Results.</bold> Monte Carlo calculated over-response of the film under the thickest part of the compensator was over 15%, which was confirmed by measurements. The magnitude of over-response could be associated with changes in the spectra of photon energy in the beam.<bold>Conclusions.</bold> The radiographic film can be used for the dosimetry of compensated high energy photon beams, with limitations in volumes where photon spectra are hardly degraded.</abstract>

Introduction. External photon beam modulation using compensators in order to achieve a desired dose distribution when brachytherapy treatment is followed by external beam radiation is a well-established technique. A compensator modulates the central part of the beam, and the dose beneath the thickest part of the compensator is delivered mostly by scattered, low energy photons. A two-dimensional detector with a good spatial resolution is needed for the verification of those beams. In this work, the influence of different types of detectors on the measured modulated dose distributions was examined.Materials and methods. Dosimetric verification was performed using X-Omat V, Eastman Kodak radiographic films at different depths in a solid water phantom. The film measurements were compared with those made by ionization chambers. Photon beams were also modelled using EGSnrc Monte Carlo algorithm to explain the measured results.Results. Monte Carlo calculated over-response of the film under the thickest part of the compensator was over 15%, which was confirmed by measurements. The magnitude of over-response could be associated with changes in the spectra of photon energy in the beam.Conclusions. The radiographic film can be used for the dosimetry of compensated high energy photon beams, with limitations in volumes where photon spectra are hardly degraded.

Dosimetric verification of compensated beams using radiographic film

Radiotherapy Department, Physics Division, University Hospital Rijeka, Rijeka, Croatia

Department of Physics, School of Medicine, Rijeka, Croatia

Department of Radiotherapy and Oncology, University Hospital Osijek, Osijek, Croatia

Radiology and Oncology

{"article-title":"Dosimetric verification of compensated beams using radiographic film"}

Introduction. External photon beam modulation using compensators in order to achieve a desired dose distribution when brachytherapy treatment is followed by...

Dosimetric verification of compensated beams using radiographic film

Published Online: Jul 20, 2011

Page range: 310 - 314

DOI: https://doi.org/10.2478/v10019-011-0020-9

Keywords
radiation therapy, dosimetry, compensators

This content is open access.

Dosimetric verification of compensated beams using radiographic film

Published Online: Jul 20, 2011

Page range: 310 - 314

DOI: https://doi.org/10.2478/v10019-011-0020-9

Keywordsradiation therapy, dosimetry, compensators

This content is open access.

Keywords
radiation therapy, dosimetry, compensators