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Potential Efficacy of the Monte Carlo Dose Calculations of 6MV Flattening Filter-Free Photon Beam of M6™ Cyberknife® System
Title
Potential Efficacy of the Monte Carlo Dose Calculations of 6MV Flattening Filter-Free Photon Beam of M6™ Cyberknife® System.
Creator
Neupane, Taindra, Shang, Charles, Leventouri, Theodora, Florida Atlantic University, Charles E. Schmidt College of Science, Department of Physics
Abstract/Description
MapCheck measurements for 50 retrospective patient’s treatment plans suggested that MapCheck could be effectively employed in routine patient specific quality assurance in M6 Cyberknife with beams delivered at different treatment angles. However, these measurements also suggested that for highly intensity modulated MLC plans, field segments of width
Show moreMapCheck measurements for 50 retrospective patient’s treatment plans suggested that MapCheck could be effectively employed in routine patient specific quality assurance in M6 Cyberknife with beams delivered at different treatment angles. However, these measurements also suggested that for highly intensity modulated MLC plans, field segments of width < 8 mm should further be analyzed with a modified (-4%) correction factor. Results of MC simulations of the M6 Cyberknife using the EGSnrc program for 2-5 millions of incident particles in BEAMnrc and 10-20 millions in DOSXYZnrc have shown dose uncertainties within 2% for open fields from 7.6 x 7.7 mm2 to 100 x 100 mm2. Energy and corresponding FWHM were optimized by comparing with water phantom measurements at 800 mm SAD resulting to E = 7 MeV and FWHM = 2.2 mm. Good agreement of dose profiles (within 2%) and outputs (within 3%) were found between the MC simulations and water phantom measurements for the open fields.
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Date Issued
2018
PURL
http://purl.flvc.org/fau/fd/FA00013147
Subject Headings
Radiosurgery--Quality control, Monte Carlo method, Radiation dosimetry
Format
Document (PDF)
Efficacy of the virtual cone method using fixed small multi-leaf collimator field for stereotactic radiosurgery
Title
Efficacy of the virtual cone method using fixed small multi-leaf collimator field for stereotactic radiosurgery.
Creator
Neupane, Taindra, Leventouri, Theodora, Shang, Charles, Florida Atlantic University, Department of Physics, Charles E. Schmidt College of Science
Abstract/Description
Dosimetric uncertainty in very small (
Show moreDosimetric uncertainty in very small (< 2 x 2 cm2) photon fields is notably higher that has created research questions when using small-field virtual cone with variable multileaf collimator (MLC) fields. We evaluate the efficacy of the virtual cone with a fixed MLC field for stereotactic radiosurgery (SRS) of small targets such as trigeminal neuralgia. We employed a virtual cone technique with a fixed field geometry, called fixed virtual cone (fVC), for small target radiosurgery using the EDGE (Varian Medical Systems, Palo Alto, CA) linac. The fVC is characterized by 0.5 cm x 0.5 cm high-definition MLC field of 10 MV flattening filter-free (FFF) beam defined at 100 cm SAD, while jaws are positioned at 1.5 cm x 1.5 cm. A spherical dose distribution equivalent to 5 mm cone was generated by using 10–14 non-coplanar partial arcs. The dosimetric accuracy of this technique was validated using the SRS MapCHECK (Sun Nuclear Corporation, FL) and the EBT3 (Ashland Inc., NJ) film based on absolute dose measurements. For the quality assurance (QA), 10 treatment plans for trigeminal neuralgia consisting of various arc fields at different collimator angles were analyzed retrospectively using 6 MV and 10 MV FFF beams, including the field-by-field study (n = 130 fields). Dose outputs were compared between the SRS MapCHECK measurements and Eclipse treatment planning system (TPS) with Acuros XB algorithm (version 16.1). In addition, important clinical parameters of 15 cases treated for trigeminal neuralgia were evaluated for the clinical performance. Moreover, dosimetric (field output factors, dose/MU) uncertainties considering a minute (± 0.5–1.0 mm) leaf shift in the field defining fVC, were examined from the TPS, SRS diode (PTW 60018) measurements, and Monte Carlo (MC) simulations.
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Date Issued
2022
PURL
http://purl.flvc.org/fau/fd/FA00013958
Subject Headings
Radiation dosimetry, Radiosurgery, Collimators (Optical instrument), Monte Carlo method
Format
Document (PDF)