Room: Exhibit Hall
Purpose: The purpose of this study was to evaluate the prompt gamma ray imaging technique according to the clinical boron concentration range during proton boron fusion therapy (PBFT).
Methods: To acquire a prompt gamma ray image from 32 projections, we simulated four head single photon emission computed tomography and a proton beam nozzle using a Monte Carlo simulation. In addition, we used a modified ordered subset expectation maximization reconstruction algorithm with a graphic processing unit for fast image acquisition. The therapeutic conditions of PBFT included a low-energy proton beam and boron concentrations from 20 to 100 Î¼g at intervals of 20 Î¼g. For quantitative analysis of the prompt gamma ray image, we acquired an image profile drawn through two boron uptake regions (BURs) and calculated the contrast value, signal-to-noise ratio (SNR), and difference between the physical target volume and volume of the prompt gamma ray image.
Results: The relative counts of prompt gamma rays were noticeably increased with increasing boron concentration. Although the intensities on the image profiles showed a similar tendency according to the boron concentration, the SNR and contrast value improved with increasing boron concentration. In addition, the difference between the physical target volume and prompt gamma ray image volume in each BUR decreased as the boron concentration increased.
Conclusion: We confirmed that the prompt gamma ray images depending on the boron concentration were successfully deducted during PBFT. This study suggests that a tumor monitoring technique using prompt gamma ray detection can be clinically applicable even if the boron concentration is relatively low.