title: Additional rectal and sigmoid mucosal points and doses in high dose rate intracavitary brachytherapy for carcinoma cervix: a dosimetric study.
abstract: BACKGROUND
  Late rectal and sigmoid toxicities seen in cervical cancer patients are attributed to brachytherapy despite rectal doses within tolerance limits. The purpose of this study was to identify additional dosimetric points which may better forecast rectal complications.
  
  
  METHODS
  Fifteen high dose rate intracavitary brachytherapy (ICA-HDR) applications with conventional X-ray and computed tomography (CT) based planning were studied. In addition to International Commission on Radiation Units and Measurement (ICRU) rectal and bladder points, proximal and distal rectal and sigmoid points were digitized on CT scans and dose volume histograms' (DVHs') parameters were computed and correlated.
  
  
  RESULTS
  The mean ICRU, additional distal, proximal and sigmoid point doses were 486 ± 152 cGy, 527 ± 156 cGy, 401 ± 149 cGy and 838 ± 254 cGy, respectively, for a prescription of 700 cGy to point A. The mean sigmoid point dose was significantly higher than the ICRU rectal point doses (P=0.001). The high-dose sigmoid points were situated at a mean -8 mm (range -22.95 to 10.43 mm) lateral, 10 mm posterior (range -15.87 to 27.82 mm) and 31 mm (range 8.08-62.91 mm) cranial to the intracavitary applicator flange of central tandem.
  
  
  CONCLUSIONS
  Our dosimetric study suggests that sigmoid points and 0.1 cm 3 receive significantly higher doses than rectal points during ICA-HDR in carcinoma of the uterine cervix. No definite conclusion on reproducible spatial distribution on orthogonal X-rays could be achieved. To document and reduce sigmoid doses, some form of 3D image-based planning is necessary.
authors: Department of Radiation Oncology, Tata Memorial Hospital, Mumbai, India. drumeshm@gmail.com
authors: Umesh
authors: U
authors: Mahantshetty
authors: Manpreet Singh
authors: MS
authors: Tiwana
authors: Swamidas
authors: S
authors: Jamema
authors: Sanjib
authors: S
authors: Mishra
authors: Reena
authors: R
authors: Engineer
authors: Deepak
authors: D
authors: Deshpande
authors: Shyamkishore
authors: S
authors: Shrivastava
mesh_terms: D001918:Brachytherapy / Q000009:adverse effects* / Q000379:methods; D012809:Colon, Sigmoid / Q000528:radiation effects*; D005260:Female; D006801:Humans; D007413:Intestinal Mucosa / Q000528:radiation effects; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted; D012007:Rectum / Q000528:radiation effects*; D002583:Uterine Cervical Neoplasms / Q000532:radiotherapy*