Acceptance Testing and Commissioning of Robotic Intensity-Modulated Radiation Therapy M6 System Equipped with InCise™2 Multileaf Collimator

Abstract

This work reports the acceptance testing and commissioning experience of the Robotic IntensityModulated Radiation Therapy (IMRT) M6 system with a newly released InCise TM 2 Multileaf Collimator (MLC) installed at the Yonsei Cancer Center. Acceptance testing included a mechanical interdigitation test, leaf positional accuracy, leakage check, and End-to-End (E2E) tests. Beam data measurements included tissue-phantom ratios (TPRs), off-center ratios (OCRs), output factors collected at 11 field sizes (the smallest field size was 7.6 mm×7.7 mm and largest field size was 115.0 mm×100.1 mm at 800 mm source-to-axis distance), and open beam profiles. The beam model was verified by checking patient-specific quality assurance (QA) in four fiducial-inserted phantoms, using 10 intracranial and extracranial patient plans. All measurements for acceptance testing satisfied manufacturing specifications. Mean leaf position offsets using the Garden Fence test were found to be 0.01±0.06 mm and 0.07±0.05 mm for X1 and X2 leaf banks, respectively. Maximum and average leaf leakages were 0.20% and 0.18%, respectively. E2E tests for five tracking modes showed 0.26 mm (6D Skull), 0.3 mm (Fiducial), 0.26 mm (Xsight Spine), 0.62 mm (Xsight Lung), and 0.6 mm (Synchrony). TPRs, OCRs, output factors, and open beams measured under various conditions agreed with composite data provided from the manufacturer to within 2%. Patient-specific QA results were evaluated in two ways. Point dose measurements with an ion chamber were all within the 5% absolute-dose agreement, and relative-dose measurements using an array ion chamber detector all satisfied the 3%/3 mm gamma criterion for more than 90% of the measurement points. The Robotic IMRT M6 system equipped with the InCise TM 2 MLC was proven to be accurate and reliable.

Patient-Specific Quality Assurance in a Multileaf Collimator-Based CyberKnife System Using the Planar Ion Chamber Array

“…A newly released M6 model, 5 th generation CyberKnife system, makes it possible to use multileaf collimator (MLC). 2) In addition to conventional benefits of CyberKnife, the use of MLC can be expected to create fields that match the tumor shape closely and spare critical organs, providing better dose distributions with an advantage in reducing beam delivery time. 3,4) The good candidates for the MLC system can be thus considered as the treatment of large targets or targets near critical organs.…”

Skin Dose Comparison of CyberKnife and Helical Tomotherapy for Head-and-Neck Stereotactic Body Radiotherapy

“…comprising 6-MV flattening filter free treatment beam with noncoplanar beam geometry and high Progress in Medical Physics 30(1), March 2019 https://doi.org/10.14316/pmp.2019.30.1.1 eISSN 2508-4453 More recently, the use of MLC has made it possible to generate dose distributions similar to the intensity modulated radiotherapy, by delivering many modulated fields with various source positions and angles 8). …”