Modulation indices and plan delivery accuracy of volumetric modulated arc therapy.

We evaluated the performance of various modulation indices (MI) for volumetric modulated arc therapy (VMAT) to predict plan delivery accuracy. The specific indices evaluated were MI quantifying the mechanical uncertainty (MIt ), MI quantifying the mechanical and dose calculation uncertainties (MIc ), MI for station parameter optimized radiation therapy (MISPORT ), modulation complexity score for VMAT (MCSv ), leaf travel modulation complexity score (LTMCS), plan averaged beam area (PA), plan averaged beam irregularity (PI), plan averaged beam modulation (PM), and plan normalized monitor unit (PMU) to predict VMAT delivery accuracy. By utilizing 240 VMAT plans generated with the Trilogy and TrueBeam STx, Spearman's rank correlation coefficients (r) were calculated between the MIs and measures of conventional methods. For the Trilogy system, MIc showed the highest r values with gamma passing rates (GPRs) (r = -0.624 with P < 0.001 for MapCHECK2 and r = -0.655 with P < 0.001 for ArcCHECK). For TrueBeam STx, MIc also showed the highest r values with GPRs (r = -0.625 with P < 0.001 for the MapCHECK2 and r = -0.561 with P < 0.001 for the ArcCHECK). The MIt and MIc showed the highest r values to the MLC position errors for the Trilogy and TrueBeam STx systems (r = 0.770 with P < 0.001 and r = 0.712 with P < 0.001, respectively). The PA showed the highest percent of r values (P < 0.05) to differences in the dose-volume parameters between original VMAT plans and actual deliveries for the Trilogy systems (30.9%). Both the MIt and MIc showed the highest percent of r values (P < 0.05) to differences in the dose-volume parameters between original VMAT plans and actual deliveries for the TrueBeam STx systems (31.8%). To comprehensively review the results, the MIc showed the best performance to predict the VMAT delivery accuracy.

Park JM ，Kim JI ，Park SY 《Journal of Applied Clinical Medical Physics》

Assessment of the modulation degrees of intensity-modulated radiation therapy plans.

Park SY ，Kim JI ，Chun M ，Ahn H ，Park JM ... -  《Radiation Oncology》

Prediction of VMAT delivery accuracy with textural features calculated from fluence maps.

Park JM ，Kim JI ，Park SY 《Radiation Oncology》

Texture analysis on the fluence map to evaluate the degree of modulation for volumetric modulated arc therapy.

Park SY ，Kim IH ，Ye SJ ，Carlson J ，Park JM ... -  《-》

Reliability of the gamma index analysis as a verification method of volumetric modulated arc therapy plans.

Park JM ，Kim JI ，Park SY ，Oh DH ，Kim ST ... -  《Radiation Oncology》