title: [Effect of prostate matching on dose distribution by on board imager kV-CBCT image].
abstract: OBJECTIVE
  The purpose of this study was to evaluate the effect of prostate matching on dose distribution using kilovolt cone beam computed tomography (kV-CBCT) with image guided radiation therapy for prostate cancer.
  
  
  METHODS
  Sixteen prostate cancer patients were treated with intensity modulated radiation therapy to 76 Gy at 2 Gy per fraction in 38 fractions. Daily target localization was performed using "bone matching" and "prostate matching" based on planning CT and kV-CBCT. Prostate dose coverage was assessed by the proportion of the CTV fully encompassed by 95%, 98% isodose lines, and mean dose lines. As for rectal and bladder, dose coverage was assessed by volumes which received 40 Gy, 60 Gy, 70 Gy, 75 Gy and mean dose at treatment. And we calculated the tumor control probability (TCP) and normal tissue complication probability (NTCP), accordingly. They were compared to the bone and prostate matching image.
  
  
  RESULTS
  Our study found an improvement in dose usage in CTV and bladder which enabled us to compare the bone matching image and the prostate matching image. However, it did not improve dose usage in the rectal. Then we chose patients who were a large shift from bone matching image to prostate matching image. As a result, rectal dose and NTCP were reduced.
  
  
  CONCLUSIONS
  Prostate matching is useful and safe when compared to bone matching because of improving CTV dose usage and reducing dose rectal and bladder.
authors: Division of Medical Quantum Science, Department of Health Sciences, Graduate School of Medical Sciences, Kyushu University.
authors: Hideaki
authors: H
authors: Hirashima
authors: Yoshiyuki
authors: Y
authors: Umezu
authors: Junichi
authors: J
authors: Fukunaga
authors: Takaaki
authors: T
authors: Hirose
authors: Hironori
authors: H
authors: Nagata
authors: Issai
authors: I
authors: Mohri
authors: Katsumasa
authors: K
authors: Nakamura
authors: Hideki
authors: H
authors: Hirata
mesh_terms: D054893:Cone-Beam Computed Tomography; D006801:Humans; D008297:Male; D011467:Prostate / Q000000981:diagnostic imaging* / Q000528:radiation effects; D011471:Prostatic Neoplasms / Q000532:radiotherapy; D011829:Radiation Dosage; D050397:Radiotherapy, Intensity-Modulated; D001743:Urinary Bladder / Q000528:radiation effects