Comparison of ArcCHECK and portal dosimetry in dose verification for intensity modulated radiotherapy plan for craniospinal irradiation

Background: To study the performance of ArcCHECK system and Portal Dosimetry (PD) used for dose verification in intensity-modulated radiotherapy (IMRT) plan of the craniospinal irradiation (CSI). Materials and Methods: A total of 12 IMRT verification plans were produced for patients who underwent CSI treatment. Each verification plan consists of three isocenter plans corresponding to head and neck (H and N), thorax, and abdomen. With different analysis criterion, ArcCHECK and PD were used for verification, and differences in the γ passing rate of verification system were evaluated using paired-samples t-test/Wilcoxon matched-pairs signed rank test. Results: With the criterion of 3%/3 mm, there was no significant difference in the average γ passing rates between H and N and abdomen (P > 0.05), but there was statistically significant difference in the average γ passing rate of the thorax (P < 0.05); With the criterion of 3%/2 mm, there was no significant difference in the passing rate (P >0.05), but there was statistically significant difference in the passing rates of thorax, abdomen and pelvis(P <0.05). When the 2%/2 mm criterion was used, the difference in the passing rates of the H and N/thorax/abdomen was statistically significant (P < 0.05). Conclusions: Both ArcCHECK and PD can be used for the dose verification of the craniospinal irradiation plan. The PD method is superior to ArcCHECK in the verification efficiency and verification accuracy. It is recommended to use the criterion of 3%/3 mm or 3%/2 mm for ArcCHECK, and 3%/2 mm or 2%/2 mm criterion for Portal Dosimetry