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It is difficult to calculate monitor units in the proton treatment planning system due to the complexity of using this system in the double scattering mode of proton therapy. Moreover, the range and spread-out Bragg peak (SOBP) values using the conversion algorithm (CONVALGO) provided by IBA (Crange, CSOBP) are different from the actual measured range (Mrange)and SOBP (MSOBP) values. In this regard, the CONVALGO (FC) value (FCrange, FCSOBP)should be measured according to the quality assurance (QA) of patient treatment, which requires physical effort and time. This study, therefore, aimed to reduce the time and effort spent on QA. The predictive model was trained using six parameters. Main option, sub-option, Mrangeand MSOBPwere used as input values, and FCrangeand FCSOBPwere used as label. The trained model predicted the CONVALGO (PC) values of PCrangeand PCSOBP. The test dataset has 261 patient data that were not used for training. Difference, mean absolute error (MAE), and root mean square error (RMSE) values were used for comparison. Compared to the FC value, the maximum difference was − 2.2 mm for PCrangeand − 3.4 mm for Crange. The acceptable standard of patient QA in our institute is within 1 mm and the number of data points that met the acceptable standard was 196 for PCrangeand 191 for Crange. For the MAE of PCSOBP, options 1, 2, and 3 showed values within 1 mm. In the MAE of CSOBP, the values were > 1 mm for all options.

In the recent study of proton therapy, the expectation of the normal tissue-sparing effect of the proton minibeam radiation therapy (pMBRT) using a multi-slit collimator (MSC) is increasing. We designed and conducted animal experiments to verify the sparing effect on normal tissues. Proton beam irradiation was carried out on two groups of mice except a control group (0 Gy). One group was irradiated with a conventional broad beam, and the other with a minibeam. A dose of 8.5 Gy was delivered to both femurs of mice in every group. In the pMBRT group, the survival rate of bone marrow cells was significantly improved as compared to the conventional broad beam group. The survival rate in the minibeam group was 2.5 times higher. In conclusion, the pMBRT has been strongly proven to have a superior tissue-sparing effect than the conventional broad beam.

Background.This study was designed to compare the quality assurance (QA) results of four dosimetric tools used for intensity modulated radiation therapy (IMRT) and to suggest universal criteria for the passing rate in QA, irrespective of the dosimetric tool used.