TY - JOUR
T1 - Adding customized electron energy beams to TrueBeam linear accelerators
AU - Gao, Song
AU - Muruganandham, Manickam
AU - Du, Weiliang
AU - Ohrt, Jared
AU - Kudchadker, Rajat J.
AU - Balter, Peter A.
N1 - Funding Information:
The authors thank Christine Wogan of MD Anderson's Division of Radiation Oncology for scientific editing of this manuscript and Mike Tham (Varian Medical Systems) for engineering support. WD is grateful to Jordan Slagowski and Garrett Baltz for the assistance in data acquisition. The data that support the findings of this study are available from the corresponding author upon reasonable request.
Publisher Copyright:
© 2022 The Authors. Journal of Applied Clinical Medical Physics published by Wiley Periodicals, LLC on behalf of The American Association of Physicists in Medicine.
PY - 2022/7
Y1 - 2022/7
N2 - Purpose: To better meet clinical needs and facilitate optimal treatment planning, we added two new electron energy beams (7 and 11 MeV) to two Varian TrueBeam linacs. Methods: We worked with the vendor to create two additional customized electron energies without hardware modifications. For each beam, we set the bending magnet current and then optimized other beam-specific parameters to achieve depths of 50% ionization (I50) of 2.9 cm for 7 MeV and 4.2 cm for the 11 MeV beam with the 15 × 15 cm2 cone at 100 cm source-to-surface distance (SSD) by using an ionization chamber profiler (ICP) with a double-wedge (DW) phantom. Beams were steered and balanced to optimize symmetry with the ICP. After all parameters were set, full commissioning was done including measuring beam profiles, percent depth doses (PDDs), output factors (OFs) at standard, and extended SSDs. Measured data were compared between the two linacs and against the values calculated by our RayStation treatment planning system (TPS) following Medical Physics Practice Guideline 5.a (MPPG 5.a) guidelines. Results: The I50 values initially determined with the ICP/DW agreed with those from a PDD-scanned in-water phantom within 0.2 mm for the 7 and 11 MeV on both linacs. Comparison of the beam characteristics from the two linacs indicated that flatness and symmetry agreed within 0.4%, and point-by-point differences in PDD were within 0.01% ± 0.3% for the 7 MeV and 0.01% ± 0.3% for the 11 MeV. The OF ratios between the two linacs were 1.000 ± 0.007 for the 7 MeV and 1.004 ± 0.007 for the 11 MeV. Agreement between TPS-calculated outputs and measurements were −0.1% ± 1.0% for the 7 MeV and 0.2% ± 0.8% for the 11 MeV. All other parameters met the MPPG 5.a's 3%/3-mm criteria. Conclusion: We were able to add two new beam energies with no hardware modifications. Tuning of the new beams was facilitated by the ICP/DW system allowing us to have the procedures done in a few hours and achieve highly consistent results across two linacs. PACS numbers: 87.55.Qr, 87.56.Fc.
AB - Purpose: To better meet clinical needs and facilitate optimal treatment planning, we added two new electron energy beams (7 and 11 MeV) to two Varian TrueBeam linacs. Methods: We worked with the vendor to create two additional customized electron energies without hardware modifications. For each beam, we set the bending magnet current and then optimized other beam-specific parameters to achieve depths of 50% ionization (I50) of 2.9 cm for 7 MeV and 4.2 cm for the 11 MeV beam with the 15 × 15 cm2 cone at 100 cm source-to-surface distance (SSD) by using an ionization chamber profiler (ICP) with a double-wedge (DW) phantom. Beams were steered and balanced to optimize symmetry with the ICP. After all parameters were set, full commissioning was done including measuring beam profiles, percent depth doses (PDDs), output factors (OFs) at standard, and extended SSDs. Measured data were compared between the two linacs and against the values calculated by our RayStation treatment planning system (TPS) following Medical Physics Practice Guideline 5.a (MPPG 5.a) guidelines. Results: The I50 values initially determined with the ICP/DW agreed with those from a PDD-scanned in-water phantom within 0.2 mm for the 7 and 11 MeV on both linacs. Comparison of the beam characteristics from the two linacs indicated that flatness and symmetry agreed within 0.4%, and point-by-point differences in PDD were within 0.01% ± 0.3% for the 7 MeV and 0.01% ± 0.3% for the 11 MeV. The OF ratios between the two linacs were 1.000 ± 0.007 for the 7 MeV and 1.004 ± 0.007 for the 11 MeV. Agreement between TPS-calculated outputs and measurements were −0.1% ± 1.0% for the 7 MeV and 0.2% ± 0.8% for the 11 MeV. All other parameters met the MPPG 5.a's 3%/3-mm criteria. Conclusion: We were able to add two new beam energies with no hardware modifications. Tuning of the new beams was facilitated by the ICP/DW system allowing us to have the procedures done in a few hours and achieve highly consistent results across two linacs. PACS numbers: 87.55.Qr, 87.56.Fc.
KW - acceptance and commissioning
KW - ionization chamber array
KW - MPPG 5.a tests
KW - new energy electron beams
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U2 - 10.1002/acm2.13633
DO - 10.1002/acm2.13633
M3 - Article
C2 - 35533212
AN - SCOPUS:85133823358
SN - 1526-9914
VL - 23
JO - Journal of applied clinical medical physics
JF - Journal of applied clinical medical physics
IS - 7
M1 - e13633
ER -