Comparison of therapeutic dosimetric data from passively scattered proton and photon craniospinal irradiations for medulloblastoma

Table 2 Dose volume histogram (DVH) analysis for photon and proton craniospinal irradiation (n = 18)

Structure, DVH dose level (Gy)	Photons		Protons		P value, Wilcoxian Signed Rank test	Significance level (P ≤ 0.05)
Structure, DVH dose level (Gy)	Mean	SD	Mean	SD	P value, Wilcoxian Signed Rank test	Significance level (P ≤ 0.05)
CTV
23.4	99.36	1.04	99.23	0.88	5.42E-01	NS
25	12.01	9.87	1.72	4.01	8.63E-04	<0.01
Spinal cord
23.4	99.16	0.85	98.91	1.46	9.83E-01	NS
25	59.02	9.15	4.64	7.52	1.96E-04	<0.01
Optic chiasm
23.4	100.00	0.00	100.00	0.00	n/a	N/A
25	3.48	4.29	3.26	3.36	5.69E-01	NS
Cochlea
23.4	99.96	0.16	99.00	3.09	1.56E-02	< 0.05
25	2.08	2.96	4.26	6.95	6.36E-01	NS
Brain stem
23.4	98.51	3.20	98.96	1.76	8.39E-01	NS
25	0.68	1.39	1.70	7.61	3.12E-02	< 0.05

Note: The table provides mean V_23.4 and V₂₅ and standard deviation (SD) values for the CTV and in-field organs for proton and photon therapy. Statistical results from Wilcoxon signed rank test (i.e., two-tailed P-value for Wilcoxon signed rank test) are also listed.
For this study 23.4 and 25 Gy is equivalent to 100% and 106.8% of the prescribed dose, respectively.

ISSN: 1748-717X