Multipleestimate Monte Carlo calculation of the dose rate constant for a cesium131 interstitial brachytherapy seed
Abstract
The purpose of this study was to calculate a more accurate dose rate constant for the Cs131 (model CS1, IsoRay Medical, Inc., Richland, Washington) interstitial brachytherapy seed. Previous measurements of the dose rate constant for this seed have been reported by others with incongruity. Recent direct measurements by thermoluminescence dosimetry and by gammaray spectroscopy were about 15 percent greater than earlier thermoluminescence dosimetry measurements. Therefore, we set about to calculate independent values by a Monte Carlo approach that combined three estimates as a consistency check, and to quantify the computational uncertainty. The calculated dose rate constant for the Cs131 seed was 1.040 cGy h^{1} U^{1} for an ionization chamber model and 1.032 cGy h^{1} U^{1} for a circular ring model. A formal value of 2.2% uncertainty was calculated for both values. The range of our multiestimate values were from 1.032 cGy h^{1} U^{1} to 1.061 cGy h^{1} U^{1}. We also modeled three I125 seeds with known dose rate constants to test the accuracy of this study's approach.
 Authors:
 Publication Date:
 Research Org.:
 Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
 Sponsoring Org.:
 USDOE
 OSTI Identifier:
 898096
 Report Number(s):
 PNNLSA48677
600301010; TRN: US0701563
 DOE Contract Number:
 AC0576RL01830
 Resource Type:
 Journal Article
 Resource Relation:
 Journal Name: Medical Physics, 34(1):4954
 Country of Publication:
 United States
 Language:
 English
 Subject:
 62 RADIOLOGY AND NUCLEAR MEDICINE; BRACHYTHERAPY; CESIUM 131; DOSE RATES; DOSIMETRY; MONTE CARLO METHOD; Cesium131 seed; dosimetry; brachytherapy; Monte Carlo; MCNP
Citation Formats
Wittman, Richard S., and Fisher, Darrell R. Multipleestimate Monte Carlo calculation of the dose rate constant for a cesium131 interstitial brachytherapy seed. United States: N. p., 2007.
Web. doi:10.1118/1.2401653.
Wittman, Richard S., & Fisher, Darrell R. Multipleestimate Monte Carlo calculation of the dose rate constant for a cesium131 interstitial brachytherapy seed. United States. doi:10.1118/1.2401653.
Wittman, Richard S., and Fisher, Darrell R. 2007.
"Multipleestimate Monte Carlo calculation of the dose rate constant for a cesium131 interstitial brachytherapy seed". United States.
doi:10.1118/1.2401653.
@article{osti_898096,
title = {Multipleestimate Monte Carlo calculation of the dose rate constant for a cesium131 interstitial brachytherapy seed},
author = {Wittman, Richard S. and Fisher, Darrell R.},
abstractNote = {The purpose of this study was to calculate a more accurate dose rate constant for the Cs131 (model CS1, IsoRay Medical, Inc., Richland, Washington) interstitial brachytherapy seed. Previous measurements of the dose rate constant for this seed have been reported by others with incongruity. Recent direct measurements by thermoluminescence dosimetry and by gammaray spectroscopy were about 15 percent greater than earlier thermoluminescence dosimetry measurements. Therefore, we set about to calculate independent values by a Monte Carlo approach that combined three estimates as a consistency check, and to quantify the computational uncertainty. The calculated dose rate constant for the Cs131 seed was 1.040 cGy h^{1} U^{1} for an ionization chamber model and 1.032 cGy h^{1} U^{1} for a circular ring model. A formal value of 2.2% uncertainty was calculated for both values. The range of our multiestimate values were from 1.032 cGy h^{1} U^{1} to 1.061 cGy h^{1} U^{1}. We also modeled three I125 seeds with known dose rate constants to test the accuracy of this study's approach.},
doi = {10.1118/1.2401653},
journal = {Medical Physics, 34(1):4954},
number = ,
volume = ,
place = {United States},
year = 2007,
month = 1
}

The aim of this work was to conduct an independent determination of the dose rate constant of the newly introduced Model CS1 {sup 131}Cs seed. A total of eight {sup 131}Cs seeds were obtained from the seed manufacturer. The airkerma strength of each seed was measured by the manufacturer whose calibration is traceable to the airkerma strength standard established for the {sup 131}Cs seeds at the National Institute of Standards and Technology (1{sigma} uncertainty <1%). The dose rate constant of each seed was measured by two independent methods: One based on the actual photon energy spectrum emitted by the seedmore »

On the dose rate constant of the selectSeed {sup 125}I interstitial brachytherapy seed
No abstract prepared. 
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