Dosimetric Characteristics and Its Impact On Plan Quality of the Adaptive Aperture of the HyperScan System
A Silvus1*, T Zhao2, T Zhang3, (1) Washington University in Saint Louis, St. Louis, MO, (2) Washington University School of Medicine, St. Louis, MO, (3) Washington University School of Medicine, St. Louis, MO
Presentations
PO-GePV-T-169 (Sunday, 7/10/2022) [Eastern Time (GMT-4)]
ePoster Forums
Purpose: To evaluate the dosimetric characteristics of the adaptive aperture (AA) of Mevion’s Hyperscan system and its impact on treatment plan quality.
Methods: Proton beams with and without AA at various airgap and energies were calculated in water. The beams lateral penumbra and distal falloff rate were evaluated and compared with a pencil beam scanning (PBS) only, Varian’s ProBeam model. Treatment plans for ten randomly selected intracranial target cases were generated using a commercial TPS system. The plan qualities were compared and benchmarked.
Results: The lateral dose gradients of the AA beam at low energies spread by 47.8% as the air gap is increased from 5 cm to 15 cm. At high energies, the lateral dose gradient for the AA beam spread by only 7.2% for the same air gap increase. At low energies for all air gaps, the lateral dose gradient for the HyperScan with AA is superior to ProBeam. The distal dose falloff rate is slower than the PBS beam at low energies and comparable at high energies. The IMPT treatment plans of most brain cases with AA beams have better conformality than the PBS only machine model.
Conclusion: The AA of HyperScan can produce improved beam penumbra when compared with conventional PBS beams. But, the distal dose falloff rate is slower than PBS beams, especially at lower energies. In most brain cases, AA plans have slightly improved conformality than PBS only plans.
Keywords
Not Applicable / None Entered.
Taxonomy
Not Applicable / None Entered.
Contact Email