Presenter of 1 Presentation
DOSE AND DOSE RATE QUANTIFICATION FOR LIVER FLASH TREATMENT PLANNING USING PROTON PBS TRANSMISSION BEAMS
Abstract
Background and Aims
This work aims to study transmission proton pencil beam scanning (PBS) FLASH radiotherapy (RT) planning for liver cancer cases based on the parameters of a commercially available proton system under FLASH mode.
Methods
An in-house TPS was developed to perform intensity-modulated proton therapy (IMPT) FLASH RT planning. Single-energy transmission PBS plans of 4.5 Gy x 15 fractions were optimized for seven hepatocellular carcinoma patients, using 2 and 5 fields combined with 1) the highest minimum MU/spot from 100-400, and minimum spot time (MST) of 2 ms; 2) the minimum MU/spot of 100, and MST of 0.5 ms. Then, the 3D average dose rate (ADR) distribution and major OARs' dose metrics were characterized to evaluate the plan quality for different combinations of field numbers and MSTs.
Results
Shorter MST are generally associated with better dose quality while more fields are only associated with better target uniformities. Fewer fields will allow higher OAR FLASH coverage with 2 ms MST compared to the 0.5 ms. For 2-field plans, dose metrics and V40Gy/s of some OARs have large variations due to selecting beam angles and the distance to the target. The transmission plans yield inferior dose quality to the conventional IMPT plans.
Conclusions
For the challenging hypofractionation liver case with smaller fractional doses (4.5Gy/fraction), using fewer fields can allow higher minimum MU/spot, resulting in higher OARs FLASH dose rate coverages while achieving similar plan quality compared to plans with more fields. Shorter MST can achieve better plan quality and comparable or even better FLASH dose rate coverage.
Author Of 1 Presentation
DOSE AND DOSE RATE QUANTIFICATION FOR LIVER FLASH TREATMENT PLANNING USING PROTON PBS TRANSMISSION BEAMS
Abstract
Background and Aims
This work aims to study transmission proton pencil beam scanning (PBS) FLASH radiotherapy (RT) planning for liver cancer cases based on the parameters of a commercially available proton system under FLASH mode.
Methods
An in-house TPS was developed to perform intensity-modulated proton therapy (IMPT) FLASH RT planning. Single-energy transmission PBS plans of 4.5 Gy x 15 fractions were optimized for seven hepatocellular carcinoma patients, using 2 and 5 fields combined with 1) the highest minimum MU/spot from 100-400, and minimum spot time (MST) of 2 ms; 2) the minimum MU/spot of 100, and MST of 0.5 ms. Then, the 3D average dose rate (ADR) distribution and major OARs' dose metrics were characterized to evaluate the plan quality for different combinations of field numbers and MSTs.
Results
Shorter MST are generally associated with better dose quality while more fields are only associated with better target uniformities. Fewer fields will allow higher OAR FLASH coverage with 2 ms MST compared to the 0.5 ms. For 2-field plans, dose metrics and V40Gy/s of some OARs have large variations due to selecting beam angles and the distance to the target. The transmission plans yield inferior dose quality to the conventional IMPT plans.
Conclusions
For the challenging hypofractionation liver case with smaller fractional doses (4.5Gy/fraction), using fewer fields can allow higher minimum MU/spot, resulting in higher OARs FLASH dose rate coverages while achieving similar plan quality compared to plans with more fields. Shorter MST can achieve better plan quality and comparable or even better FLASH dose rate coverage.