A systematic approach to statistical analysis in dosimetry and patient-specific IMRT plan verification measurements

Table 1 Patient specific IMRT QA absolute dose measurement analysis

Meas. Num (n)	Measurement result (Gy)	Mean value (1 to n)	Result standard deviation (1 to n)	Estimated dose delivery standard deviation	Probability for the mean to be within 2% accuracy (1 to n)	Probability for the mean to be within 3% accuracy (1 to n)
a. Chamber 1: corresponding plan dose was 1.702 Gy
1	1.706	1.706	-		-	-
2	1.695	1.700	0.008	0.010	89.63%	93.05%
3	1.695	1.699	0.006	0.007	98.85%	99.50%
4	1.689	1.696	0.007	0.008	99.76%	99.93%
5	1.689	1.695	0.007	0.007	99.96%	99.98%
b. Chamber 2: corresponding plan dose was 0.546 Gy
1	0.513	0.513	-		-	-
2	0.507	0.510	0.005	0.006	80.50%	86.76%
3	0.504	0.508	0.005	0.006	93.11%	96.77%
4	0.504	0.507	0.005	0.005	97.94%	99.33%
5	0.502	0.506	0.005	0.005	99.25%	99.83%

The measurements were conducted without the QA phantom re-setup between each measurement and the statistical analysis was for the accuracy of measurement itself. The accuracy is defined as percent difference between the expected value and measurement mean value.

ISSN: 1748-717X