On the use of high dose rate {sup 192}Ir and {sup 169}Yb sources with the MammoSite registered radiation therapy system
- Medical Physics Department, Medical School, University of Athens, 75 Mikras Asias, 11527, Athens (Greece)
Ample literature exists on the dose overestimation by commercially available treatment planning systems in MammoSite registered applications using high dose rate {sup 192}Ir sources for partial breast brachytherapy as monotherapy, due to their inability to predict the dose reduction caused by the radiographic contrast solution in the balloon catheter. In this work Monte Carlo simulation is used to verify the dose rate reduction in a balloon breast applicator which does not vary significantly with distance and it is 1.2% at the prescription distance for the reference simulated geometry of 10% diluted radiographic contrast media and 2.5 cm balloon radius. Based on these findings and the minimal hardening of the initially emitted photon spectrum for {sup 192}Ir, a simple analytical method is proposed and shown capable for correcting dosimetry planning in clinical applications. Simulations are also performed to assess the corresponding dose reduction in applications of balloon breast applicators using high dose rate {sup 169}Yb sources that have recently become available. Results yield a far more significant and distance dependent dose reduction for {sup 169}Yb (on the order of 20% at the prescription distance for the abovementioned reference simulation geometry). This dose reduction cannot be accounted for using simple analytical methods as for {sup 192}Ir due to the significant hardening of the initially emitted {sup 169}Yb photons within the diluted radiographic contrast media. Combined with results of previous works regarding the effect of altered scatter conditions (relative to treatment planning system assumptions) on breast treatment planning accuracy, which is more pronounced for {sup 169}Yb relative to {sup 192}Ir, these findings call for the amendment of dose treatment planning systems before using {sup 169}Yb high dose rate sources in balloon breast applicators.
- OSTI ID:
- 21032698
- Journal Information:
- Medical Physics, Journal Name: Medical Physics Journal Issue: 9 Vol. 34; ISSN 0094-2405; ISSN MPHYA6
- Country of Publication:
- United States
- Language:
- English
Similar Records
On the use of HDR {sup 60}Co source with the MammoSite Radiation Therapy System
Effects of breast-air and breast-lung interfaces on the dose rate at the planning target volume of a MammoSite catheter for Yb-169 and Ir-192 HDR sources
A dosimetric comparison of {sup 169}Yb and {sup 192}Ir for HDR brachytherapy of the breast, accounting for the effect of finite patient dimensions and tissue inhomogeneities
Journal Article
·
Sun Dec 14 23:00:00 EST 2008
· Medical Physics
·
OSTI ID:22095268
Effects of breast-air and breast-lung interfaces on the dose rate at the planning target volume of a MammoSite catheter for Yb-169 and Ir-192 HDR sources
Journal Article
·
Sun Aug 15 00:00:00 EDT 2010
· Medical Physics
·
OSTI ID:22096741
A dosimetric comparison of {sup 169}Yb and {sup 192}Ir for HDR brachytherapy of the breast, accounting for the effect of finite patient dimensions and tissue inhomogeneities
Journal Article
·
Thu Dec 14 23:00:00 EST 2006
· Medical Physics
·
OSTI ID:20853826