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Valdes‐Cortez C, Niatsetski Y, Perez‐Calatayud J, Ballester F, Vijande J. A Monte Carlo study of the relative biological effectiveness in surface brachytherapy. Med Phys 2022; 49:5576-5588. [DOI: 10.1002/mp.15774] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Revised: 05/11/2022] [Accepted: 05/15/2022] [Indexed: 11/07/2022] Open
Affiliation(s)
| | - Yury Niatsetski
- R&D Elekta Brachytherapy Waardgelder 1, 3905 TH Veenendaal The Netherlands
| | - Jose Perez‐Calatayud
- Unidad Mixta de Investigación en Radiofísica e Instrumentación Nuclear en Medicina (IRIMED) Instituto de Investigación Sanitaria La Fe (IIS‐La Fe)‐Universitat de Valencia (UV)
- Radiotherapy Department La Fe Hospital Valencia Spain
- Radiotherapy Department Hospital Clinica Benidorm Alicante Spain
| | - Facundo Ballester
- Unidad Mixta de Investigación en Radiofísica e Instrumentación Nuclear en Medicina (IRIMED) Instituto de Investigación Sanitaria La Fe (IIS‐La Fe)‐Universitat de Valencia (UV)
- Department of Atomic, Molecular and Nuclear Physics University of Valencia Burjassot Spain
| | - Javier Vijande
- Unidad Mixta de Investigación en Radiofísica e Instrumentación Nuclear en Medicina (IRIMED) Instituto de Investigación Sanitaria La Fe (IIS‐La Fe)‐Universitat de Valencia (UV)
- Department of Atomic, Molecular and Nuclear Physics University of Valencia Burjassot Spain
- Instituto de Física Corpuscular IFIC (UV‐CSIC) Burjassot Spain
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Valdes-Cortez C, Ballester F, Vijande J, Gimenez V, Gimenez-Alventosa V, Perez-Calatayud J, Niatsetski Y, Andreo P. Depth-dose measurement corrections for the surface electronic brachytherapy beams of an Esteya ® unit: a Monte Carlo study. Phys Med Biol 2020; 65. [DOI: 10.1088/1361-6560/ab9773] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Accepted: 05/28/2020] [Indexed: 11/12/2022]
Abstract
Abstract
Three different correction factors for measurements with the parallel-plate ionization chamber PTW T34013 on the Esteya electronic brachytherapy unit have been investigated. This chamber type is recommended by AAPM TG-253 for depth-dose measurements in the 69.5 kV x-ray beam generated by the Esteya unit.
Monte Carlo simulations using the PENELOPE-2018 system were performed to determine the absorbed dose deposited in water and in the chamber sensitive volume at different depths with a Type A uncertainty smaller than 0.1%. Chamber-to-chamber differences have been explored performing measurements using three different chambers. The range of conical applicators available, from 10 to 30 mm in diameter, has been explored.
Using a depth-independent global chamber perturbation correction factor without a shift of the effective point of measurement yielded differences between the absorbed dose to water and the corrected absorbed dose in the sensitive volume of the chamber of up to 1% and 0.6% for the 10 mm and 30 mm applicators, respectively. Calculations using a depth-dependent perturbation factor, including or excluding a shift of the effective point of measurement, resulted in depth-dose differences of about ± 0.5% or less for both applicators. The smallest depth-dose differences were obtained when a shift of the effective point of measurement was implemented, being displaced 0.4 mm towards the center of the sensitive volume of the chamber. The correction factors were obtained with combined uncertainties of 0.4% (k = 2). Uncertainties due to chamber-to-chamber differences are found to be lower than 2%.
The results emphasize the relevance of carrying out detailed Monte Carlo studies for each electronic brachytherapy device and ionization chamber used for its dosimetry.
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