title: Planning design of locally advanced pancreatic carcinoma using 4DCT and IMRT/IGRT technologies.
abstract: OBJECTIVE
  to study the impact of the 4DCT imaging technique on radiotherapy planning for pancreatic carcinoma. To evaluate the possibility of IMRT/IGRT to increase the dose to PTV subvolume.
  
  
  METHODS
  contrast-enhanced 4DCT scans of 15 patients (PTs) with unresectable pancreatic cancer were acquired. A 4DCT based PTV (4D-PTV) was created by the convolution of contours and then expanded for geometric uncertainties; a standard PTV (STD-PTV) was derived from a single CTV plus conventional margins. Two 3D conformal treatment (3DCRT) plans and one Helical Tomotherapy (HT) plan were generated with a prescription of 60 Gy. Regarding the 3DCRT plans, the 4D-PTV was considered as the target volume for one, and the STD-PTV for the other; the HT plans were performed only for 4D-PTV. Twelve of 15 PTs were admitted to a Phase I hypofractionated study (15 fractions). The prescribed dose was 44.25 Gy to the 4D-PTV and the PTV subvolume around vascular involvement was boosted from 50 to 55 Gy; before treatment, daily patient position was corrected using MVCT.
  
  
  RESULTS
  4D-PTVs were smaller than STD-PTVs with a volume reduction equal to 37%. 3DCRT plans on 4D-PTV showed a significant sparing of most OARs, the use of IMRT allowed a further significant dose reduction. In the Phase I study the PTV subvolume received up to 55 Gy with modest increase in dose to OARs.
  
  
  CONCLUSIONS
  the 4DCT procedure decreases the overlap between PTV and OARs. HT technique, compared with 3DCRT, allows efficient dose sparing in particular for the duodenum. The IMRT/IGRT approach allows a safe dose escalation to PTV subvolume.
authors.affiliation: Medical Physics Department, San Raffaele Scientific Institute, Milan, Italy.
authors.forename: Giulia
authors.initials: G
authors.lastname: Sangalli
authors.forename: Paolo
authors.initials: P
authors.lastname: Passoni
authors.forename: Giovanni M
authors.initials: GM
authors.lastname: Cattaneo
authors.forename: Sara
authors.initials: S
authors.lastname: Broggi
authors.forename: Valentino
authors.initials: V
authors.lastname: Bettinardi
authors.forename: Michele
authors.initials: M
authors.lastname: Reni
authors.forename: Najla
authors.initials: N
authors.lastname: Slim
authors.forename: Nadia Di
authors.initials: ND
authors.lastname: Muzio
authors.forename: Riccardo
authors.initials: R
authors.lastname: Calandrino
mesh_terms: D000328:Adult; D000368:Aged; D004386:Duodenum / Q000528:radiation effects; D005260:Female; D056973:Four-Dimensional Computed Tomography; D006801:Humans; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D010190:Pancreatic Neoplasms / Q000473:pathology / Q000532:radiotherapy*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted; D050397:Radiotherapy, Intensity-Modulated / Q000009:adverse effects; D016896:Treatment Outcome