skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: SU-F-T-13: Transit Dose Comparisons for Co-60 and Ir-192 HDR Sources

Abstract

Purpose: The purpose of this study is to compare the transit dose due to the movement of high dose rate (HDR) Ir-192 and Co-60 sources along the transfer tube. This is performed by evaluating air-kerma differences in the vicinity of the transfer tube when both sources are moved with the same velocity from a HDR brachytherapy afterloader into a patient. Methods: Monte Carlo simulations have been performed using PENELOPE2014. mHDR-v2 and Flexisource sources have been considered. Collisional kerma has been scored. The sources were simulated within a plastic catheter located in an infinite air phantom. The movement of the seed was included by displacing their positions along the connecting catheter from z=−75 cm to z=+75 cm and combining them. Backscatter from the afterloader and the patient was not considered. Since modern afterloaders like Flexitron (Elekta) or Saginova (Bebig) are able to use equally Ir-192 and Co-60 sources it was assumed that both sources are displaced with equal speed. Typical content activity values were provided by the manufacturer (460 GBq for Ir-192 and 75 GBq for Co-60). Results: 2D distributions were obtained with type-A uncertainties (k=2) less than 0.01%. From those, the air kerma ratio Co-60/Ir-192 was evaluated weighted by theirmore » corresponding activities. It was found that it varies slowly with distance (less than 10% variation) but strongly in time due to the shorter half-life of the Ir-192 (73.83 days). The maximum ratio is located close to the catheter with a value of 0.57 when both sources are installed by the manufacturer, while increasing up to 1.25 at the end of the recommended working life (90 days) of the Ir-192 source. Conclusion: Air-kerma ratios are almost constant (0.51–0.57) in the vicinity of the source. Nevertheless, air-kerma ratios increase rapidly whenever the Ir-192 is approaching the end of its life.« less

Authors:
;  [1];  [2];  [3]
  1. University of Valencia, Burjassot (Spain)
  2. University of Valencia and IFIC(CSIC-UV), Burjassot (Spain)
  3. Hospital Clinica Benidorm, Benidorm, and Hospital Universitari i Politecnic La Fe, Valencia (Spain)
Publication Date:
OSTI Identifier:
22642263
Resource Type:
Journal Article
Resource Relation:
Journal Name: Medical Physics; Journal Volume: 43; Journal Issue: 6; Other Information: (c) 2016 American Association of Physicists in Medicine; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
60 APPLIED LIFE SCIENCES; 61 RADIATION PROTECTION AND DOSIMETRY; BRACHYTHERAPY; COBALT 60; DOSE RATES; HALF-LIFE; IRIDIUM 192; KERMA; MONTE CARLO METHOD; PATIENTS; PHANTOMS; RADIATION DOSES

Citation Formats

Gimenez-Alventosa, V, Ballester, F, Vijande, J, and Perez-Calatayud, J. SU-F-T-13: Transit Dose Comparisons for Co-60 and Ir-192 HDR Sources. United States: N. p., 2016. Web. doi:10.1118/1.4956147.
Gimenez-Alventosa, V, Ballester, F, Vijande, J, & Perez-Calatayud, J. SU-F-T-13: Transit Dose Comparisons for Co-60 and Ir-192 HDR Sources. United States. doi:10.1118/1.4956147.
Gimenez-Alventosa, V, Ballester, F, Vijande, J, and Perez-Calatayud, J. Wed . "SU-F-T-13: Transit Dose Comparisons for Co-60 and Ir-192 HDR Sources". United States. doi:10.1118/1.4956147.
@article{osti_22642263,
title = {SU-F-T-13: Transit Dose Comparisons for Co-60 and Ir-192 HDR Sources},
author = {Gimenez-Alventosa, V and Ballester, F and Vijande, J and Perez-Calatayud, J},
abstractNote = {Purpose: The purpose of this study is to compare the transit dose due to the movement of high dose rate (HDR) Ir-192 and Co-60 sources along the transfer tube. This is performed by evaluating air-kerma differences in the vicinity of the transfer tube when both sources are moved with the same velocity from a HDR brachytherapy afterloader into a patient. Methods: Monte Carlo simulations have been performed using PENELOPE2014. mHDR-v2 and Flexisource sources have been considered. Collisional kerma has been scored. The sources were simulated within a plastic catheter located in an infinite air phantom. The movement of the seed was included by displacing their positions along the connecting catheter from z=−75 cm to z=+75 cm and combining them. Backscatter from the afterloader and the patient was not considered. Since modern afterloaders like Flexitron (Elekta) or Saginova (Bebig) are able to use equally Ir-192 and Co-60 sources it was assumed that both sources are displaced with equal speed. Typical content activity values were provided by the manufacturer (460 GBq for Ir-192 and 75 GBq for Co-60). Results: 2D distributions were obtained with type-A uncertainties (k=2) less than 0.01%. From those, the air kerma ratio Co-60/Ir-192 was evaluated weighted by their corresponding activities. It was found that it varies slowly with distance (less than 10% variation) but strongly in time due to the shorter half-life of the Ir-192 (73.83 days). The maximum ratio is located close to the catheter with a value of 0.57 when both sources are installed by the manufacturer, while increasing up to 1.25 at the end of the recommended working life (90 days) of the Ir-192 source. Conclusion: Air-kerma ratios are almost constant (0.51–0.57) in the vicinity of the source. Nevertheless, air-kerma ratios increase rapidly whenever the Ir-192 is approaching the end of its life.},
doi = {10.1118/1.4956147},
journal = {Medical Physics},
number = 6,
volume = 43,
place = {United States},
year = {Wed Jun 15 00:00:00 EDT 2016},
month = {Wed Jun 15 00:00:00 EDT 2016}
}