title: Comparative evaluation of two-dimensional radiography and three dimensional computed tomography based dose-volume parameters for high-dose-rate intracavitary brachytherapy of cervical cancer: a prospective study.
abstract: BACKGROUND
  Dosimetric comparison of two dimensional (2D) radiography and three-dimensional computed tomography (3D-CT) based dose distributions with high-dose-rate (HDR) intracavitry radiotherapy (ICRT) for carcinoma cervix, in terms of target coverage and doses to bladder and rectum.
  
  
  METHODS
  Sixty four sessions of HDR ICRT were performed in 22 patients. External beam radiotherapy to pelvis at a dose of 50 Gray in 27 fractions followed by HDR ICRT, 21 Grays to point A in 3 sessions, one week apart was planned . All patients underwent 2D-orthogonal and 3D-CT simulation for each session. Treatment plans were generated using 2D-orthogonal images and dose prescription was made at point A. 3D plans were generated using 3D-CT images after delineating target volume and organs at risk. Comparative evaluation of 2D and 3D treatment planning was made for each session in terms of target coverage (dose received by 90%, 95% and 100% of the target volume: D90, D95 and D100 respectively) and doses to bladder and rectum: ICRU-38 bladder and rectum point dose in 2D planning and dose to 0.1cc, 1cc, 2cc, 5cc, and 10cc of bladder and rectum in 3D planning.
  
  
  RESULTS
  Mean doses received by 100% and 90% of the target volume were 4.24 ± 0.63 and 4.9 ± 0.56 Gy respectively. Doses received by 0.1cc, 1cc and 2cc volume of bladder were 2.88 ± 0.72, 2.5 ± 0.65 and 2.2 ± 0.57 times more than the ICRU bladder reference point. Similarly, doses received by 0.1cc, 1cc and 2cc of rectum were 1.80 ± 0.5, 1.48 ± 0.41 and 1.35 ± 0.37 times higher than ICRU rectal reference point.
  
  
  CONCLUSIONS
  Dosimetric comparative evaluation of 2D and 3D CT based treatment planning for the same brachytherapy session demonstrates underestimation of OAR doses and overestimation of target coverage in 2D treatment planning.
authors: Department of Radiation Oncology, Dr. B. R. Ambedkar Institute Rotary Cancer Hospital, New Delhi, India E-mail : drspathy@gmail.com.
authors: Renu
authors: R
authors: Madan
authors: Sushmita
authors: S
authors: Pathy
authors: Vellaiyan
authors: V
authors: Subramani
authors: Seema
authors: S
authors: Sharma
authors: Bidhu Kalyan
authors: BK
authors: Mohanti
authors: Subhash
authors: S
authors: Chander
authors: Sanjay
authors: S
authors: Thulkar
authors: Lalit
authors: L
authors: Kumar
authors: Vatsla
authors: V
authors: Dadhwal
mesh_terms: D001918:Brachytherapy / Q000379:methods; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods; D008875:Middle Aged; D011446:Prospective Studies; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods; D012007:Rectum / Q000473:pathology; D014057:Tomography, X-Ray Computed / Q000379:methods; D001743:Urinary Bladder / Q000473:pathology; D002583:Uterine Cervical Neoplasms / Q000473:pathology* / Q000532:radiotherapy*