Presenter of 1 Presentation
EVALUATION OF PROTON FLASH TREATMENT PLANS USING TRANSMISSION AND RIDGE-FILTER SOBP TECHNIQUES
Abstract
Background and Aims
Recent proton FLASH research focuses on transmission planning to exploit the higher beam transport efficiency for high energies, with some compromises to plan quality. This study explores the plan quality and achievable dose rates for transmission and spread-out Bragg peak using a ridge-filter. The results utilise a FLASH effectiveness factor that incorporates dose and dose rate to facilitate an overall plan quality comparison between plans.
Methods
Three spot-reduced, single-field plans were optimised for three patients: IMPT using down-stream range-shifters with consecutive delivery of energy layers; IMPT using down-stream range-shifters with simultaneous delivery of all energies for each lateral spot position, simulating a personalised variable ridge-filter; transmission using the highest available energy of 229MeV. The fraction dose was 1x22.3Gy (equivalent to 30x2Gy and tumour alpha/beta=10Gy). The potential FLASH effects were estimated by multiplying any dose contribution delivered in FLASH state by a FLASH effectiveness factor FEF=0.67. The FLASH state was triggered in a voxel if any dose contribution was delivered above 40Gy/s and 5/10/15Gy and was assumed to persist for 200ms after the trigger has ended.
Results
Figure 1 shows very similar and pronounced FLASH effects for ridge-filter deliveries compared with transmission plans. Figure 2 suggests a potential clinical benefit of the FEF-weighted ridge-filter plans compared with a clinical reference plan’s physical dose, with positive values indicating a reduced integral dose.
Conclusions
With encouraging FLASH characteristics and excellent dose conformality, variable ridge-filters might be a promising approach to bring FLASH proton therapy to clinics.
Author Of 1 Presentation
EVALUATION OF PROTON FLASH TREATMENT PLANS USING TRANSMISSION AND RIDGE-FILTER SOBP TECHNIQUES
Abstract
Background and Aims
Recent proton FLASH research focuses on transmission planning to exploit the higher beam transport efficiency for high energies, with some compromises to plan quality. This study explores the plan quality and achievable dose rates for transmission and spread-out Bragg peak using a ridge-filter. The results utilise a FLASH effectiveness factor that incorporates dose and dose rate to facilitate an overall plan quality comparison between plans.
Methods
Three spot-reduced, single-field plans were optimised for three patients: IMPT using down-stream range-shifters with consecutive delivery of energy layers; IMPT using down-stream range-shifters with simultaneous delivery of all energies for each lateral spot position, simulating a personalised variable ridge-filter; transmission using the highest available energy of 229MeV. The fraction dose was 1x22.3Gy (equivalent to 30x2Gy and tumour alpha/beta=10Gy). The potential FLASH effects were estimated by multiplying any dose contribution delivered in FLASH state by a FLASH effectiveness factor FEF=0.67. The FLASH state was triggered in a voxel if any dose contribution was delivered above 40Gy/s and 5/10/15Gy and was assumed to persist for 200ms after the trigger has ended.
Results
Figure 1 shows very similar and pronounced FLASH effects for ridge-filter deliveries compared with transmission plans. Figure 2 suggests a potential clinical benefit of the FEF-weighted ridge-filter plans compared with a clinical reference plan’s physical dose, with positive values indicating a reduced integral dose.
Conclusions
With encouraging FLASH characteristics and excellent dose conformality, variable ridge-filters might be a promising approach to bring FLASH proton therapy to clinics.