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Table 3 Ablative radiotherapy prescription definitions and normal tissue constraints

From: Ablative radiation therapy for locally advanced pancreatic cancer: techniques and results

 

Planning Volumes

Definition

Doses by Fractionation Scheme

15-Fraction

25-Fraction

Prescriptions

Microscopic Extension PTV

CTV + 5 mm

CTV = GTV + 1 cm + CA, SMA, +/− porta hepatis, +/− splenic hilum basins

37.5Gy/15

45Gy/25

High Dose PTV

GTV + 0-5 mm margin excluding GI OAR + 5–7 margin

67.5Gy/15

75Gy/25

Ultra High Dose PTVa

1 cm contraction of High Dose PTV

90Gy/15

100Gy/25

Constraints

Stomach-Duodenum PRV

Stomach and duodenum segments 1 and 2 + 3-5 mm

Dmax <45Gy

Dmax <60Gy

Small Bowel PRV

All other small bowel + 3-5 mm

Dmax <40Gy

Dmax <55Gy

Large Bowel PRV

Large bowel + 3-5 mm

Dmax <50Gy

Dmax <65Gy

  1. aPossible in select patients only