SU-F-T-575: Verification of a Monte-Carlo Small Field SRS/SBRT Dose Calculation System
- University of California San Francisco, San Francisco, CA (United States)
Purpose: To develop a methodology for validation of a Monte-Carlo dose calculation model for robotic small field SRS/SBRT deliveries. Methods: In a robotic treatment planning system, a Monte-Carlo model was iteratively optimized to match with beam data. A two-part analysis was developed to verify this model. 1) The Monte-Carlo model was validated in a simulated water phantom versus a Ray-Tracing calculation on a single beam collimator-by-collimator calculation. 2) The Monte-Carlo model was validated to be accurate in the most challenging situation, lung, by acquiring in-phantom measurements. A plan was created and delivered in a CIRS lung phantom with film insert. Separately, plans were delivered in an in-house created lung phantom with a PinPoint chamber insert within a lung simulating material. For medium to large collimator sizes, a single beam was delivered to the phantom. For small size collimators (10, 12.5, and 15mm), a robotically delivered plan was created to generate a uniform dose field of irradiation over a 2×2cm{sup 2} area. Results: Dose differences in simulated water between Ray-Tracing and Monte-Carlo were all within 1% at dmax and deeper. Maximum dose differences occurred prior to dmax but were all within 3%. Film measurements in a lung phantom show high correspondence of over 95% gamma at the 2%/2mm level for Monte-Carlo. Ion chamber measurements for collimator sizes of 12.5mm and above were within 3% of Monte-Carlo calculated values. Uniform irradiation involving the 10mm collimator resulted in a dose difference of ∼8% for both Monte-Carlo and Ray-Tracing indicating that there may be limitations with the dose calculation. Conclusion: We have developed a methodology to validate a Monte-Carlo model by verifying that it matches in water and, separately, that it corresponds well in lung simulating materials. The Monte-Carlo model and algorithm tested may have more limited accuracy for 10mm fields and smaller.
- OSTI ID:
- 22649150
- Journal Information:
- Medical Physics, Journal Name: Medical Physics Journal Issue: 6 Vol. 43; ISSN 0094-2405; ISSN MPHYA6
- Country of Publication:
- United States
- Language:
- English
Similar Records
MO-FG-BRA-01: 4D Monte Carlo Simulations for Verification of Dose Delivered to a Moving Anatomy
SU-E-T-519: Investigation of the CyberKnife MultiPlan Monte Carlo Dose Calculation Using EBT3 Film Absolute Dosimetry for Delivery in a Heterogeneous Thorax Phantom
Poster — Thur Eve — 31: Dosimetric Effect of Respiratory Motion on RapidArc Lung SBRT Treatment Delivered by TrueBeam Linear Accelerator
Journal Article
·
Wed Jun 15 00:00:00 EDT 2016
· Medical Physics
·
OSTI ID:22653865
SU-E-T-519: Investigation of the CyberKnife MultiPlan Monte Carlo Dose Calculation Using EBT3 Film Absolute Dosimetry for Delivery in a Heterogeneous Thorax Phantom
Journal Article
·
Mon Jun 15 00:00:00 EDT 2015
· Medical Physics
·
OSTI ID:22548557
Poster — Thur Eve — 31: Dosimetric Effect of Respiratory Motion on RapidArc Lung SBRT Treatment Delivered by TrueBeam Linear Accelerator
Journal Article
·
Fri Aug 15 00:00:00 EDT 2014
· Medical Physics
·
OSTI ID:22407654