Normal liver tissue sparing by intensity-modulated proton stereotactic body radiotherapy for solitary liver tumours

Figures & data

Table I. Constraints to targets and organs at risk.

Target or organ at risk	Constraints
CTV	142.5% at the CTV surface Dmax < 160%
PTV	100% at the PTV surface
Liver	VD < 15 Gy > 700 cm^3
Duodenum	D1 cm^3 < 21 Gy
Stomach	D1 cm^3 < 21 Gy
Spinal cord	Dmax < 18 Gy
Right or left kidney	D50% < 15 Gy
Total kidney volume	D35% < 15 Gy
Heart	D1 cm^3 < 30 Gy

Figure 1. Patient with solitary liver metastasis (CTV = 84 cm³) planned with IMRT (left) and IMPT (right). Threshold for dose colour wash is 15 Gy. Red and purple lines indicate CTV and PTV, respectively.

Figure 2. Mean DVHs for normal liver (excluding CTV) for 10 patients with solitary liver metastasis planned with IMRT and IMPT. The prescribed dose for both plans was 16.75 Gy × 3 (level D).

Figure 3. Volume of spared normal liver (CTV excluded) receiving a dose lower than 15 Gy (V_{D < 15Gy}) plotted according to the volume of the CTV. The prescribed dose for both plans in this figure was 16.75 Gy × 3 (level D).

Figure 4. Mean dose (D_mean) to the normal liver (CTV excluded) plotted according to volume of the CTV. The prescribed dose for both plans in this figure was 16.75 Gy × 3 (level D).