title: On the performances of Intensity Modulated Protons, RapidArc and Helical Tomotherapy for selected paediatric cases.
abstract: BACKGROUND
  To evaluate the performance of three different advanced treatment techniques on a group of complex paediatric cancer cases.
  
  
  METHODS
  CT images and volumes of interest of five patients were used to design plans for Helical Tomotherapy (HT), RapidArc (RA) and Intensity Modulated Proton therapy (IMP). The tumour types were: extraosseous, intrathoracic Ewing Sarcoma; mediastinal Rhabdomyosarcoma; metastasis of base of skull with bone, para-nasal and left eye infiltration from Nephroblastoma of right kidney; metastatic Rhabdomyosarcoma of the anus; Wilm's tumour of the left kidney with multiple liver metastases. Cases were selected for their complexity regardless the treatment intent and stage. Prescribed doses ranged from 18 to 53.2 Gy, with four cases planned using a Simultaneous Integrated Boost strategy. Results were analysed in terms of dose distributions and dose volume histograms.
  
  
  RESULTS
  For all patients, IMP plans lead to superior sparing of organs at risk and normal healthy tissue, where in particular the integral dose is halved with respect to photon techniques. In terms of conformity and of spillage of high doses outside targets (external index (EI)), all three techniques were comparable; CI90% ranged from 1.0 to 2.3 and EI from 0 to 5%. Concerning target homogeneity, IMP showed a variance (D5%-D95%) measured on the inner target volume (highest dose prescription) ranging from 5.9 to 13.3%, RA from 5.3 to 11.8%, and HT from 4.0 to 12.2%. The range of minimum significant dose to the same target was: (72.2%, 89.9%) for IMP, (86.7%, 94.1%) for RA, and (79.4%, 94.8%) for HT. Similarly, for maximum significant doses: (103.8%, 109.4%) for IMP, (103.2%, 107.4%) for RA, and (102.4%, 117.2%) for HT. Treatment times (beam-on time) ranged from 123 to 129 s for RA and from 146 to 387 s for HT.
  
  
  CONCLUSIONS
  Five complex pediatric cases were selected as representative examples to compare three advanced radiation delivery techniques. While differences were noted in the metrics examined, all three techniques provided satisfactory conformal avoidance and conformation.
authors.affiliation: Oncology Institute of Southern Switzerland, Medical Physics Unit, Bellinzona, Switzerland. Antonella.Fogliata-Cozzi@eoc.ch
authors.forename: Antonella
authors.initials: A
authors.lastname: Fogliata
authors.forename: Slav
authors.initials: S
authors.lastname: Yartsev
authors.forename: Giorgia
authors.initials: G
authors.lastname: Nicolini
authors.forename: Alessandro
authors.initials: A
authors.lastname: Clivio
authors.forename: Eugenio
authors.initials: E
authors.lastname: Vanetti
authors.forename: Rolf
authors.initials: R
authors.lastname: Wyttenbach
authors.forename: Glenn
authors.initials: G
authors.lastname: Bauman
authors.forename: Luca
authors.initials: L
authors.lastname: Cozzi
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D004307:Dose-Response Relationship, Radiation; D005260:Female; D006801:Humans; D008297:Male; D009369:Neoplasms / Q000532:radiotherapy*; D061766:Proton Therapy; D011880:Radiotherapy Planning, Computer-Assisted; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*; D036542:Tomography, Spiral Computed; D011522:Protons
chemical_list: D011522:Protons