title: Sector analysis of 125I permanent prostate brachytherapy provides a rapid and effective method of evaluating and comparing pre- and post-implant dosimetry.
abstract: OBJECTIVE
  To evaluate a sector analysis program in the assessment and comparison of pre- and post-implant dosimetric parameters during the development of an (125)I permanent prostate brachytherapy service.
  
  
  METHODS
  A total of 50 consecutive men being treated with permanent prostate brachytherapy had dose-volume analysis in 12 sectors of their pre-implant ultrasound (USpre) and post-implant CT (CTpost) studies. Individual sectors were created by dividing prostate into three equal lengths, namely base, midgland, and apex. Each of these volumes was then divided into four axial sectors. Dosimetric parameters were compared in adjoining sectors within each study and between studies.
  
  
  RESULTS
  There were statistically significant differences between individual sectors on USpre and CTpost volumes with CTpost higher than USpre (p=0.001). Statistically significant differences were found in corresponding sectors on USpre and CTpost for all dosimetric parameters. The dosimetric parameters were significantly lower on CTpost in the anterior base and midgland (p=0.001) and significantly higher at the posterior apex and midgland (p=0.05). Dose homogeneity was demonstrated in adjoining sectors in all USpre and most adjoining sectors on CTpost.
  
  
  CONCLUSIONS
  Sector analysis allows rapid assessment of USpre and CTpost dosimetry. It offers a scientific method of identifying areas of increased and reduced dosing on CTpost when compared with USpre, providing a learning tool to refine dosimetric analysis and highlight sectors where implant quality could be improved.
authors: Department of Radiotherapy Medical Physics, Northern Ireland Cancer Centre, Belfast Health & Social Care Trust, Belfast City Hospital, Lisburn Road, Belfast, Antrim, Northern Ireland BT9 7AB, UK. ahamed.badusha@belfasttrust.hscni.net
authors: Ahamed Badusha
authors: AB
authors: Mohamed Yoosuf
authors: Geraldine
authors: G
authors: Workman
authors: Monica M
authors: MM
authors: O'Toole
authors: Margaret
authors: M
authors: Straney
authors: Rejina
authors: R
authors: Verghis
authors: Eoin
authors: E
authors: Napier
authors: Darren M
authors: DM
authors: Mitchell
mesh_terms: D000368:Aged; D001918:Brachytherapy / Q000379:methods*; D003627:Data Interpretation, Statistical; D005500:Follow-Up Studies; D006801:Humans; D066298:In Vitro Techniques; D007457:Iodine Radioisotopes / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy*; D011879:Radiotherapy Dosage; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome
chemical_list: D007457:Iodine Radioisotopes