Table 1.

Planning dosimetry for the dose-probability PTV plans, and its change from the clinical and ITV-based PTV plans.

Dose-probability PTV plans on mid- position CT, AVG±SD		Δ in dose-probability PTV plan parameters on mid- position CT compared to:
		Clinical PTV plan on exhale CT, Δ AVG±SD	ITV-based PTV plan on exhale CT, Δ AVG±SD
Target dosimetry
PTV–GTV volume	128±69 cm3	−70±45 cm3 or −35±9 %*	−79±41 cm3 or −38±3 %*
Nominal prescription	40.3±7.6 Gy	3.9±2.8 Gy or 9±5%*	3.7±2.4 Gy, or 9±6%*
PTVD95	42.6±8.4 Gy	4.5±3.0 Gy or 10±6%*	4.0±2.8 Gy or 9±5%*
Normal liver dosimetry
Mean dose (excluding GTV)	16.1±3.2 Gy	−0.4±1.5 Gy or −3±9%	−0.5±1.7 Gy or −3±11 %
Effective volume‖,	0.39±0.12	−0.05±0.04*	−0.05±0.06*
Liver NTCP¶,	2.4±4.0 %	−0.5±1.5%	−0.5±1.4%
PTV coverage quality
Volume receiving ≥ prescribed dose	99±1%	1±1%*	0±1%
RTOG conformality index†	1.29±0.15	0.0±0.22	−0.06±0.14
RTOG coverage quality index††	0.98±0.05	0.05±0.12	0.03±0.11
RTOG homogeneity index#	1.17±0.06	−0.04±0.05*	−0.03±0.05

Abbreviations: AVG=average; CT=computed tomography; GTV=gross tumor volume; ITV=internal target volume; NTCP=normal tissue complication probability; PTV=planning target volume; PTVD95=dose to 95% of the PTV; RTOG=Radiation Therapy Oncology Group; SD=standard deviation.

Notes:

^*p<0.01 two-tailed paired Student’s T-test;

^‖calculated as per Kutcher et al.(19);

^¶calculated with Lyman-linear quadratic model corrected for the dose/fraction (α/β=2.5 Gy)(14);

^†ratio of nominal prescription isodose volume/PTV;

^††ratio of min PTV dose to 0.5cm³/nominal prescription dose;

^#ratio b of max PTV dose to 0.5cm³/nominal prescription dose.