Dosimetric comparison between VMAT with different dose calculation algorithms and protons for soft-tissue sarcoma radiotherapy

Figures & data

Figure 1. Arc and beam arrangement for two typical cases (A and B): RapidArc on the left, proton plans on the right.

Figure 2. Isodose distributions. First row: RapidArc photon plan, 6 ×, dose to medium calculation; second row: proton plan.

Figure 3. Average DVHs for PTV and bone for all plans: RapidArc (AAA, Acuros XB dose to medium M, Acuros XB dose to water W), protons. Data refer to plans individually normalised to mean PTV.

Table I. Statistics summary. For each parameter the mean ± SD over all the 10 plans is reported.

	6 ×
	AAA	Acuros_M	Acuros_W	Protons
PTV
Mean [Gy]	66.5±0.0	66.5±0.0	66.5±0.0	66.5±0.0
St. Dev. [Gy]	3.1±0.7	3.0±0.7	3.0±0.7	2.3±0.9
D2% [Gy]	71.1±0.9	71.2±0.8	71.2±0.8	69.8±1.4
D98% [Gy]	57.2±3.0	57.3±3.2	57.7±2.7	59.4±3.5
V90% [%]	96.1±1.9	96.2±1.9	96.4±1.9	97.6±1.7
V95% [%]	90.4±3.2	90.9±3.4	90.6±3.2	94.7±2.9
V110% [%]	0.1±0.2	0.2±0.2	0.2±0.2	0.4±0.5
Bone
Dmax [Gy]	54.1±2.2	53.8±2.2	55.1±2.1	57.3±6.7
D1cm3 [Gy]	49.7±2.3	49.6±2.2	51.5±2.1	49.0±4.8
D2cm3 [Gy]	49.1±2.5	48.9±2.4	50.9±2.3	47.0±5.2
D5cm3 [Gy]	47.9±2.8	47.7±2.7	50.0±2.4	43.2±6.4
V35Gy [cm^3]	16184±7790	15888±7812	17931±7908	5105±7604
V40Gy [cm^3]	8458±5054	7991±5001	11362±5561	2675±4323
V45Gy [cm^3]	2649±2054	2405±1885	5048±3065	1060±1941
V50Gy [cm^3]	312±518	251±422	913±1035	304±687
Healthy Tissue
V5Gy [%]	32.4±8.9	32.6±9.1	32.7±9.1	10.5±4.5
V50Gy [%]	3.2±1.7	3.3±1.7	3.3±1.7	2.1±0.8
V60Gy [%]	1.0±0.5	1.1±0.5	1.1±0.5	1.0±0.6
DoseInt^*[Gy*dm^3]	177.8±77.8	179.3±78.9	179.5±78.8	88.6±49.8

^*DoseInt, dose integral.

Table II. MU summary as percentage difference between plans.

	6 ×
MU: (AAA) – (Acuros_Medium)	−1.8% ±0.3% [ <0.001]
MU: (Acuros_Water) – (Acuros_Medium)	−0.4% ±0.6% [0.039]

In square brackets the p-values.