title: Helical tomotherapy vs. intensity-modulated proton therapy for whole pelvis irradiation in high-risk prostate cancer patients: dosimetric, normal tissue complication probability, and generalized equivalent uniform dose analysis.
abstract: OBJECTIVE
  To compare intensity-modulated proton therapy (IMPT) and helical tomotherapy (HT) treatment plans for high-risk prostate cancer (HRPCa) patients.
  
  
  METHODS
  The plans of 8 patients with HRPCa treated with HT were compared with IMPT plans with two quasilateral fields set up (-100°; 100°) and optimized with the Hyperion treatment planning system. Both techniques were optimized to simultaneously deliver 74.2 Gy/Gy relative biologic effectiveness (RBE) in 28 fractions on planning target volumes (PTVs)3-4 (P + proximal seminal vesicles), 65.5 Gy/Gy(RBE) on PTV2 (distal seminal vesicles and rectum/prostate overlapping), and 51.8 Gy/Gy(RBE) to PTV1 (pelvic lymph nodes). Normal tissue calculation probability (NTCP) calculations were performed for the rectum, and generalized equivalent uniform dose (gEUD) was estimated for the bowel cavity, penile bulb and bladder.
  
  
  RESULTS
  A slightly better PTV coverage and homogeneity of target dose distribution with IMPT was found: the percentage of PTV volume receiving ≥ 95% of the prescribed dose (V(95%)) was on average > 97% in HT and > 99% in IMPT. The conformity indexes were significantly lower for protons than for photons, and there was a statistically significant reduction of the IMPT dosimetric parameters, up to 50 Gy/Gy(RBE) for the rectum and bowel and 60 Gy/Gy(RBE) for the bladder. The NTCP values for the rectum were higher in HT for all the sets of parameters, but the gain was small and in only a few cases statistically significant.
  
  
  CONCLUSIONS
  Comparable PTV coverage was observed. Based on NTCP calculation, IMPT is expected to allow a small reduction in rectal toxicity, and a significant dosimetric gain with IMPT, both in medium-dose and in low-dose range in all OARs, was observed.
authors.affiliation: Agenzia Provinciale per Protonterapia, Trento, Italy. widesott@yahoo.it
authors.forename: Lamberto
authors.initials: L
authors.lastname: Widesott
authors.forename: Alessio
authors.initials: A
authors.lastname: Pierelli
authors.forename: Claudio
authors.initials: C
authors.lastname: Fiorino
authors.forename: Antony J
authors.initials: AJ
authors.lastname: Lomax
authors.forename: Maurizio
authors.initials: M
authors.lastname: Amichetti
authors.forename: Cesare
authors.initials: C
authors.lastname: Cozzarini
authors.forename: Martin
authors.initials: M
authors.lastname: Soukup
authors.forename: Ralf
authors.initials: R
authors.lastname: Schneider
authors.forename: Eugen
authors.initials: E
authors.lastname: Hug
authors.forename: Nadia
authors.initials: N
authors.lastname: Di Muzio
authors.forename: Riccardo
authors.initials: R
authors.lastname: Calandrino
authors.forename: Marco
authors.initials: M
authors.lastname: Schwarz
mesh_terms: D019583:Dose Fractionation, Radiation; D006801:Humans; D008198:Lymph Nodes / Q000000981:diagnostic imaging; D015182:Lymphatic Irradiation; D008297:Male; D058958:Organs at Risk / Q000000981:diagnostic imaging / Q000528:radiation effects; D010388:Pelvis; D010413:Penis / Q000000981:diagnostic imaging / Q000528:radiation effects; D017785:Photons / Q000627:therapeutic use; D011467:Prostate / Q000000981:diagnostic imaging / Q000528:radiation effects; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology / Q000532:radiotherapy*; D061766:Proton Therapy; D011832:Radiation Injuries / Q000517:prevention & control; D011859:Radiography; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*; D012007:Rectum / Q000000981:diagnostic imaging / Q000528:radiation effects; D012062:Relative Biological Effectiveness; D012669:Seminal Vesicles / Q000528:radiation effects; D011522:Protons
chemical_list: D011522:Protons