Energy Modulated Photon Radiotherapy: A Monte Carlo Feasibility Study
Table 5
Comparison of PTV indices between IMRT plan and EMXRT plan for the six cases in this study.
Tumor site
Indices
IMRT/Gy
EMXRT/Gy
Relative difference/%
Prostate
66.6
66.6
0.0
74.5
74.1
−0.5
63.9
62.9
−1.6
80.1
79.0
−1.4
HI
0.22
0.22
0.0
Head and neck
68
68.0
0.0
72.1
71.9
−0.3
67.8
67.8
0.0
79.2
79.4
+0.3
HI
0.16
0.16
0.0
Lung
50.0
50.0
0.0
53
52.9
−0.2
48.8
48.5
−0.6
57.6
56.9
−1.2
HI
0.17
0.16
−5.9
Spine
20.0
20.0
0.0
20.6
20.8
+1.0
19.4
19.4
0.0
23.5
23.9
+1.7
HI
0.19
0.21
+10.5
Brain
20.0
20.0
0.0
20.5
20.5
0.0
19.6
19.8
+1.0
22.5
22.6
+0.4
HI
0.14
0.13
−7.1
Thyroid
68.0
68.0
0.0
72.1
71.9
−0.3
67.8
67.8
0.0
79.2
79.4
0.3
HI
0.16
0.16
0.0
Relative difference = 100% × ( − )/. , , and are the mean, maximum, and minimum doses of PTV, respectively. and are the dose levels covering 98% and 2% of the PTV volume, respectively. HI = ( − )/.
