Table 6.

Median values for mean and maximum doses to target volumes and organs-at-risk by radiotherapy modality for tumors of the posterior cranial fossa.

Modality	CTV	PTV	iON	cON	BS	Csm	iSVZ	cSVZ	iThal	cThal	iHip	cHip	Pitu	HT	WB	IT	ST
MEAN DOSE
3DCRT	98.7	97.8	4.5	6.1	54.5	11.7	7.2	3.6	2.7	2.6	30.8	25.9	18.7	10.6	13.5	52.0	8.0
VMAT	99.8	99.3	10.6	8.5	57.8	15.1	5.1	4.0	3.5	3.6	32.4	28.3	26.4	16.1	13.5	56.1	7.0
PRT	99.7	98.6	0.0	0.0	58.6	0.6	10.3	5.2	7.8	7.1	42.5	27.5	0.9	0.9	8.6	43.3	6.0
%change, PRT vs. 3DCRT	+1	0	−100	−100	0	−82	−39	−59	−32	−35	−16	−16	−86	−72	−27	−12	−45
%change, PRT vs. VMAT	0	−1	−100	−100	−2	−84	−28	−44	−35	−43	−35	−22	−95	−77	−26	−18	−30
MAXIMUM DOSE
3DCRT	103.2	103.2	11.0	21.3	99.6	25.6	60.1	32.3	6.3	6.1	91.1	64.8	25.6	29.9	103.2	103.1	98.3
VMAT	102.9	103.3	24.1	20.1	101.4	29.6	49.6	32.4	13.5	15.8	87.6	54.5	30.5	34.2	103.3	102.7	102.0
PRT	104.9	104.9	0.3	0.3	101.6	3.0	40.5	32.2	29.6	29.3	86.8	64.2	2.2	4.3	104.9	104.9	102.4
% change, 3DCRT vs. PRT	+1	+1	−94	−96	+1	−42	−35	−28	20	4	+2	+1	−81	−45	+1	+1	+2
% change, VMAT vs. PRT	0	0	−98	−98	0	−51	−12	−8	14	12	+1	+5	−91	−61	0	+1	−2

All values expressed as percentage of prescription dose. The percent change between modalities was calculated as ((PRT/other modality) × 100) − 100 for each patient; the median value for all patients is reported in the table. CTV: clinical target volume; PTV: planning target volume; i: ipsilateral; c: contralateral; ON: optic nerve; BS: brainstem; Csm: chiasm; SVZ: subventricular zone; Thal: thalamus; Hip: hippocampus; Pitu: pituitary; HT: hypothalamus; IT: infratentorial (normal) brain; ST: supratentorial (normal) brain; 3DCRT: three-dimensional conformal radiotherapy; VMAT: volumetric modulated arc therapy; PRT: proton radiotherapy.