Test purpose
Investigation of the constancy of IQM signal for conventional intensity modulated radiation therapy (IMRT) and rotational volumetric modulated arc therapy (VMAT)
Test method
The stationary and rotational dosimetric constancy of IQM was evaluated, using five field IMRT and single- and double-arc VMAT plans for prostate and head-and-neck (H&N) patients.
The plans were repeated three times for each measurement over several days to assess the constancy of IQM response.
Test results
Repeated IQM measurements of prostate and H&N IMRT deliveries showed 0.4 and 0.5% average standard deviation (SD) for segment-by-segment comparison and 0.1 and 0.2% for cumulative comparison. The corresponding SDs of the cumulative signal for VMAT deliveries were 0.7, 1.3%, respectively.
Conclusion
IQM provides an effective means for realtime dosimetric verification of IMRT/VMAT treatment delivery.
