title: Proton therapy coverage for prostate cancer treatment.
abstract: OBJECTIVE
  To determine the impact of prostate motion on dose coverage in proton therapy.
  
  
  METHODS
  A total of 120 prostate positions were analyzed on 10 treatment plans for 10 prostate patients treated using our low-risk proton therapy prostate protocol (University of Florida Proton Therapy Institute 001). Computed tomography and magnetic resonance imaging T(2)-weighted turbo spin-echo scans were registered for all cases. The planning target volume included the prostate with a 5-mm axial and 8-mm superoinferior expansion. The prostate was repositioned using 5- and 10-mm one-dimensional vectors and 10-mm multidimensional vectors (Points A-D). The beam was realigned for the 5- and 10-mm displacements. The prescription dose was 78 Gy equivalent (GE).
  
  
  RESULTS
  The mean percentage of rectum receiving 70 Gy (V(70)) was 7.9%, the bladder V(70) was 14.0%, and the femoral head/neck V(50) was 0.1%, and the mean pelvic dose was 4.6 GE. The percentage of prostate receiving 78 Gy (V(78)) with the 5-mm movements changed by -0.2% (range, 0.006-0.5%, p > 0.7). However, the prostate V(78) after a 10-mm displacement changed significantly (p < 0.003) with different movements: 3.4% (superior), -5.6% (inferior), and -10.2% (posterior). The corresponding minimal doses were also reduced: 4.5 GE, -4.7 GE, and -11.7 GE (p < or = 0.003). For displacement points A-D, the clinical target volume V(78) coverage had a large and significant reduction of 17.4% (range, 13.5-17.4%, p < 0.001) in V(78) coverage of the clinical target volume. The minimal prostate dose was reduced 33% (25.8 GE), on average, for Points A-D. The prostate minimal dose improved from 69.3 GE to 78.2 GE (p < 0.001) with realignment for 10-mm movements.
  
  
  CONCLUSIONS
  The good dose coverage and low normal doses achieved for the initial plan was maintained with movements of < or = 5 mm. Beam realignment improved coverage for 10-mm displacements.
authors: University of Florida Proton Therapy Institute, Jacksonville, FL 32206, USA. c2002@ufl.edu
authors: Carlos
authors: C
authors: Vargas
authors: Marcus
authors: M
authors: Wagner
authors: Chaitali
authors: C
authors: Mahajan
authors: Daniel
authors: D
authors: Indelicato
authors: Amber
authors: A
authors: Fryer
authors: Aaron
authors: A
authors: Falchook
authors: David
authors: D
authors: Horne
authors: Angela
authors: A
authors: Chellini
authors: Craig
authors: C
authors: McKenzie
authors: Paula
authors: P
authors: Lawlor
authors: Zuofeng
authors: Z
authors: Li
authors: Liyong
authors: L
authors: Lin
authors: Sameer
authors: S
authors: Keole
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D005269:Femur; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009068:Movement; D010388:Pelvis; D011467:Prostate / Q000000981:diagnostic imaging; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology / Q000532:radiotherapy*; D061766:Proton Therapy; D011879:Radiotherapy Dosage; D012007:Rectum; D014057:Tomography, X-Ray Computed; D047368:Tumor Burden; D001743:Urinary Bladder; D011522:Protons
chemical_list: D011522:Protons