Energy Modulated Photon Radiotherapy: A Monte Carlo Feasibility Study

Table 8

Comparison of dosimetric indices between the IMRT and the EMXRT plans for the extra lung and brain case.

Case	Tumor site	Indices	IMRT	EMXRT	Relative difference/%
Extra lung	PTV	/Gy	54.0	54.0	0.0
		/Gy	54.5	54.1	−0.7
		HI	0.23	0.22	−6.6
	Trachea	/Gy	1.71	1.64	−4.1
	Great vessel	/Gy	4.09	3.87	−5.4
	Spinal cord	/Gy	1.53	1.19	−22.2
	Esophagus	/Gy	2.62	2.34	−10.7
	Lungs	/Gy	4.39	3.77	−14.1
			18.80%	16.90%	−10.1
			6.92%	6.70%	−0.3
Extra brain	PTV	/Gy	16.1	16.1	0.0
		/Gy	16.0	16.0	0.0
		HI	0.23	0.23	0.0
	Chiasm	/Gy	12.6	12.5	−0.8
	Brainstem	/Gy	9.8	9.2	−5.7
	LtOpticNerve	/Gy	10.7	10.4	−2.8
	RtOpticNerve	/Gy	8.3	8.1	−2.4

Relative difference = 100%  ×  ( − )/. is the mean doses of each organ/tissue. HI = ( − )/. , , and are the dose levels covering 98%, 2%, and 50% of the PTV volume, respectively. and are the percent of whole lung volume receiving 5 Gy and 20 Gy dose, respectively.