title: Assessment of organ dose reduction and secondary cancer risk associated with the use of proton beam therapy and intensity modulated radiation therapy in treatment of neuroblastomas.
abstract: BACKGROUND
  To compare proton beam therapy (PBT) and intensity-modulated radiation therapy (IMRT) with conformal radiation therapy (CRT) in terms of their organ doses and ability to cause secondary cancer in normal organs.
  
  
  METHODS
  Five patients (median age, 4 years; range, 2-11 years) who underwent PBT for retroperitoneal neuroblastoma were selected for treatment planning simulation. Four patients had stage 4 tumors and one had stage 2A tumor, according to the International Neuroblastoma Staging System. Two patients received 36 Gy, two received 21.6 Gy, and one received 41.4 Gy of radiation. The volume structures of these patients were used for simulations of CRT and IMRT treatment. Dose-volume analyses of liver, stomach, colon, small intestine, pancreas, and bone were performed for the simulations. Secondary cancer risks in these organs were calculated using the organ equivalent dose (OED) model, which took into account the rates of cell killing, repopulation, and the neutron dose from the treatment machine.
  
  
  RESULTS
  In all evaluated organs, the mean dose in PBT was 20-80% of that in CRT. IMRT also showed lower mean doses than CRT for two organs (20% and 65%), but higher mean doses for the other four organs (110-120%). The risk of secondary cancer in PBT was 24-83% of that in CRT for five organs, but 121% of that in CRT for pancreas. The risk of secondary cancer in IMRT was equal to or higher than CRT for four organs (range 100-124%).
  
  
  CONCLUSIONS
  Low radiation doses in normal organs are more frequently observed in PBT than in IMRT. Assessments of secondary cancer risk showed that PBT reduces the risk of secondary cancer in most organs, whereas IMRT is associated with a higher risk than CRT.
authors.affiliation: Division of Proton Therapy, Shizuoka Cancer Center Hospital, 1007 Shimonagakubo, Nagaizumi, Shizuoka 411-8777, Japan. h.fuji@scchr.jp.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Fuji
authors.forename: Uwe
authors.initials: U
authors.lastname: Schneider
authors.forename: Yuji
authors.initials: Y
authors.lastname: Ishida
authors.forename: Masahiro
authors.initials: M
authors.lastname: Konno
authors.forename: Haruo
authors.initials: H
authors.lastname: Yamashita
authors.forename: Yuki
authors.initials: Y
authors.lastname: Kase
authors.forename: Shigeyuki
authors.initials: S
authors.lastname: Murayama
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Onoe
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Ogawa
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Harada
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Asakura
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Nishimura
mesh_terms: D002648:Child; D002675:Child, Preschool; D003198:Computer Simulation; D005260:Female; D006801:Humans; D008297:Male; D009367:Neoplasm Staging; D009381:Neoplasms, Radiation-Induced / Q000175:diagnosis / Q000517:prevention & control; D009447:Neuroblastoma / Q000532:radiotherapy*; D061766:Proton Therapy / Q000009:adverse effects / Q000379:methods*; D011829:Radiation Dosage; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted; D020266:Radiotherapy, Conformal / Q000009:adverse effects / Q000379:methods*; D050397:Radiotherapy, Intensity-Modulated / Q000009:adverse effects / Q000379:methods*; D012186:Retroperitoneal Neoplasms / Q000532:radiotherapy; D012306:Risk; D014018:Tissue Distribution