title: Patient-specific quality assurance for prostate cancer patients receiving spot scanning proton therapy using single-field uniform dose.
abstract: OBJECTIVE
  To describe our experiences with patient-specific quality assurance (QA) for patients with prostate cancer receiving spot scanning proton therapy (SSPT) using single-field uniform dose (SFUD).
  
  
  METHODS
  The first group of 249 patients with prostate cancer treated with SSPT using SFUD was included in this work. The scanning-beam planning target volume and number of monitor units were recorded and checked for consistency. Patient-specific dosimetric measurements were performed, including the point dose for each plan, depth doses, and two-dimensional (2D) dose distribution in the planes perpendicular to the incident beam direction for each field at multiple depths. The γ-index with 3% dose or 3-mm distance agreement criteria was used to evaluate the 2D dose distributions.
  
  
  RESULTS
  We observed a linear relationship between the number of monitor units and scanning-beam planning target volume. The difference between the measured and calculated point doses (mean ± SD) was 0.0% ± 0.7% (range, -2.9% to 1.8%). In general, the depth doses exhibited good agreement except at the distal end of the spread-out Bragg peak. The pass rate of γ-index (mean ± SD) for 2D dose comparison was 96.2% ± 2.6% (range, 90-100%). Discrepancies between the measured and calculated dose distributions primarily resulted from the limitation of the model used by the treatment planning system.
  
  
  CONCLUSIONS
  We have established a patient-specific QA program for prostate cancer patients receiving SSPT using SFUD.
authors.affiliation: Department of Radiation Physics, University of Texas M. D. Anderson Cancer Center, Houston, TX 77030, USA. xrzhu@mdanderson.org
authors.forename: X Ronald
authors.initials: XR
authors.lastname: Zhu
authors.forename: Falk
authors.initials: F
authors.lastname: Poenisch
authors.forename: Xiaofei
authors.initials: X
authors.lastname: Song
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Johnson
authors.forename: George
authors.initials: G
authors.lastname: Ciangaru
authors.forename: M Brad
authors.initials: MB
authors.lastname: Taylor
authors.forename: MingFwu
authors.initials: M
authors.lastname: Lii
authors.forename: Craig
authors.initials: C
authors.lastname: Martin
authors.forename: Bijan
authors.initials: B
authors.lastname: Arjomandy
authors.forename: Andrew K
authors.initials: AK
authors.lastname: Lee
authors.forename: Seungtaek
authors.initials: S
authors.lastname: Choi
authors.forename: Quynh Nhu
authors.initials: QN
authors.lastname: Nguyen
authors.forename: Michael T
authors.initials: MT
authors.lastname: Gillin
authors.forename: Narayan
authors.initials: N
authors.lastname: Sahoo
mesh_terms: D000465:Algorithms; D006801:Humans; D055909:Magnetic Field Therapy / Q000379:methods / Q000592:standards; D008297:Male; D019047:Phantoms, Imaging; D057285:Precision Medicine / Q000379:methods / Q000592:standards; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy*; D061766:Proton Therapy; D011785:Quality Assurance, Health Care / Q000379:methods*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods* / Q000592:standards; D020266:Radiotherapy, Conformal / Q000379:methods* / Q000592:standards; D014057:Tomography, X-Ray Computed / Q000379:methods; D011522:Protons
chemical_list: D011522:Protons