The feasibility and implementation of a golden beam model in Monaco treatment planning system

doi:10.19401/j.cnki.1007-3639.2023.05.005

Abstract

Abstract:

Background and purpose: Accelerated go live (AGL) is the entire management process for medical accelerators from installation, commissioning, modeling to radiotherapy implementation. Compared with the traditional time-consuming accelerator acceptance process, AGL has established a set of gold standard models based on the big data of thousands of medical accelerators, which makes the accelerator installation greatly optimized in the data acquisition and modeling stage. This study aimed to evaluate and verify an efficient beam modeling method for Monaco treatment planning system (TPS) using golden beam data (GBD). Methods: Two Elekta Infinity™ linear accelerators with agility head in the Department of Radiation Oncology, Fudan University Shanghai Cancer Center, were installed and matched with the GBD. Then, a customer acceptance test (CAT) and beam model validations were performed on measured percentage depth dose (PDD) and profile for open-field (OF) point-doses in a three-dimensional water tank. Furthermore, a total of 16 clinical cases from different sites were used for radiotherapy planning design, measurement and dose analysis to validate and verify the accuracy of the beam model. Results: For beam model verification, the agreement of all validation PDD and profile was larger than 90%, and the majority point passing rate was larger than 95% (99.4% for linac 1 and 98.5% for linac 2). For point-dose validation, 96.8% and 97.2% of OF point measured were found to be within 2% agreement of TPS-calculations for linac 1 and linac 2, respectively. The deviation of R50 and R90 between TPS calculation and measured were within 3 mm at all evaluated points of electron beam. The Gamma passing rate for all plans was greater than 90% when using 3%/3 mm criteria, and point-dose agreement was within 3%. Conclusion: Compared with the traditional accelerator process from installation to commission, the Monaco TPS modeling process AGL based on GBD can not only ensure the model accuracy, but also shorten the entire process time, which has the feasibility of clinical application.

Key words: Golden beam model, Accelerator acceptance, Treatment planning system

CLC Number:

R730.55

ZHONG Yang, YANG Yanju, ZHAO Jun, HU Weigang. The feasibility and implementation of a golden beam model in Monaco treatment planning system[J]. China Oncology, 2023, 33(5): 452-459.

Figures/Tables 6

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Measurements	Equipment	SSD D/cm	Depth D/cm	Field size/applicator (cm²)
In-plane and cross-plane profile	IBA compact ionization chamber CC13™ and CC06™, 3D Blue Phantom™ water tank	90	5, 10, 20	Field size (photons): 3×3, 5×5, 10×10, 30×30, 40×30; Applicators (electron): 6×6, 10×10, 14×14, 20×20, 25×25
Depth dose	IBA compact ionization chamber CC13™, and CC06™, 3D Blue Phantom™ water tank	90, 100		Field size (photons): 10×10, 40×30;Applicators (electron): 6×6, 10×10, 14×14, 20×20, 25×25
60° Wedge depth dose and profile	IBA compact ionization chamber CC13™, 3D Blue Phantom™ water tank	90	10	10×10, 40×30
Absolute dosimetry	Farmer chamber PTW 30013, 3D water phantom PTW	100	Zeff	10×10
Output factor	Farmer chamber PTW 30013, 3D water phantom PTW	100	Zeff	Applicators (electron): 6×6, 10×10, 14×14, 20×20, 25×25

Item	Energy	Linac 1		Linac 2		Tolerance
Item	Energy	Reference	Measured	Reference	Measured	Tolerance
Beam penetration quality^a	6 MV	67.5%	67.4%	67.5%	67.5%	1%
	10 MV	73.0%	72.6%	73.0%	72.4%	1%
	6 MV FFF	67.5%	67.4%	67.5%	67.5%	1%
	6 MeV	20 mm	19.6 mm	20 mm	20.18 mm	±0.5 mm
	9 MeV	30 mm	30.1 mm	30 mm	30.19 mm	±0.5 mm
	12 MeV	40 mm	40 mm	40 mm	40.00 mm	±0.5 mm
	15 MeV	50 mm	49.9 mm	50 mm	50.20 mm	±0.5 mm
Wedge factor^b	6 MV	0.265	0.266	0.265	0.2659	0.002
	10 MV	0.28	0.28	0.28	0.281	0.002