Fan-Shaped Complete Block on Helical Tomotherapy for Esophageal Cancer: A Phantom Study

Table 1

Quantitative dose indices for lungs, spinal cord, heart, and tumor for treatment plan of nonblock and various FSCB designs.

	Nonblock	FSCB 90°	FSCB 100°	FSCB 110°	FSCB 120°	FSCB 130°	FSCB 140°
Lungs
MLD (Gy)	14.53 ± 0.94	9.38 ± 0.26	9.06 ± 0.11	8.73 ± 0.09	8.12 ± 0.04	7.33 ± 0.32	7.05 ± 0.04
(%)	18.04 ± 0.91	11.76 ± 1.46	11.42 ± 0.47	10.70 ± 0.99	10.57 ± 0.80	10.28 ± 1.02	9.38 ± 0.13
(%)	36.84 ± 0.22	21.11 ± 2.03	20.10 ± 0.77	18.85 ± 0.30	17.27 ± 0.37	14.49 ± 1.86	14.13 ± 0.27
(%)	77.19 ± 4.72	34.34 ± 1.03	32.24 ± 0.16	30.31 ± 3.71	28.14 ± 1.48	21.10 ± 2.40	20.68 ± 0.26
(%)	97.03 ± 0.12	54.07 ± 0.63	52.41 ± 0.80	46.74 ± 1.35	41.50 ± 0.68	33.41 ± 1.32	30.79 ± 0.19
Spinal cord
maximum dose (Gy)	33.57 ± 0.57	41.64 ± 0.79	41.87 ± 0.64	42.86 ± 0.45	43.41 ± 0.15	44.02 ± 0.14	44.45 ± 0.10
Heart
mean dose (Gy)	20.93 ± 0.50	29.15 ± 0.83	29.27 ± 0.36	31.03 ± 0.41	31.50 ± 1.11	32.11 ± 0.94	32.41 ± 0.37
(%)	6.72 ± 0.03	13.97 ± 1.22	15.07 ± 0.94	17.60 ± 0.44	19.02 ± 3.77	23.26 ± 1.59	25.78 ± 0.50
PTV
CN	0.91 ± 0.00	0.82 ± 0.02	0.82 ± 0.01	0.82 ± 0.00	0.77 ± 0.02	0.75 ± 0.03	0.71 ± 0.01
HI	1.02 ± 0.00	1.04 ± 0.00	1.04 ± 0.00	1.06 ± 0.00	1.07 ± 0.00	1.07 ± 0.01	1.07 ± 0.00