M Xu¹*, R Foster¹, Y Qin¹, J Wei², (1) Northwestern Medicine, Geneva and Warrenville, IL, (2) Varian Medical Systems, Southeastern Regional Medical Center, 600 Celebrate Life PKWY, Newnan, GA

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  M Xu

TU-I345-IePD-F6-3 (Tuesday, 7/12/2022) 3:45 PM - 4:15 PM [Eastern Time (GMT-4)]

Exhibit Hall | Forum 6

Purpose: The objective of this study is to compare the self-developed approach GRID treatment planning method and the commercial available method in the treatment planning system (TPS).

Methods: A commercial GRID block (.decimal, Sanford, FL) was used for the treatment of large and bulky tumors clinically as Spatially Fractionated Radiation Therapy (SFRT). There was no physical GRID block add-on option in Eclipse TPS. We developed a virtual GRID structure in the model and co-registered it with patient imaging. The .decimal company provided the GRID model in DICOM format, which required most anonymization of the DICOM file for import/export to TPS. We used the self-developed and commercial available methods for GRID planning in Eclipse TPS.

Results: For a 12x13x13 cm3 pelvis-mass GTV, a GRID-plan with SSD-setup and a prescribed depth of 13 cm produced a strong dose gradient along the beam axis. Both plans showed a lateral valley-to peak ratio was about 30.5% at dmax. For the two plans with the 15 MV beam, the dose differences were less than 0.3% for the maximum dose and mean dose. The calculated MU difference was 1.6%, and the commercial plan achieved a slightly smaller number of MUs. DVH for GTV coverage showed no significant difference for both methods.

Conclusion: The two approaches of self-developed and commercial GRID planning are comparable in accuracy, simplicity, and efficiency. However, home-made method can rapidly produce GRID dose, dose distribution, and MU in a time window of approximately one hour whereas commercial services can take several days.

Keywords

Grids, Treatment Planning

Taxonomy

TH- External Beam- Photons: General (most aspects)

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