title: Image-guided brachytherapy for cervical cancer: analysis of D2 cc hot spot in three-dimensional and anatomic factors affecting D2 cc hot spot in organs at risk.
abstract: OBJECTIVE
  To analyze the D2 cc hot spot in three-dimensional CT and anatomic factors affecting the D2 cc hot spot in organs at risk (OARs).
  
  
  METHODS
  Thirty-one patients underwent pelvic CT scan after insertion of the applicator. High-dose-rate treatment planning was performed with standard loading patterns. The D2 cc structures in OARs were generated in three dimensional if the total equivalent dose in 2 Gy exceeded our defined dose limits (hot spot). The location of D2 cc hot spot was defined as the center of the largest D2 cc fragment. The relationship between the hot spot and the applicator position was reported in Digital Imaging and Communication in Medicine coordinates.
  
  
  RESULTS
  The location of sigmoid, small bowel, and bladder D2 cc hot spots was around the endocervix: The mean location of sigmoid hot spot for lateral view was 1.6 cm posteriorly and 2.3 cm superiorly (Y, 1.6 and Z, 2.3), small bowel was 1.6 cm anteriorly and 2.7 cm superiorly (Y, -1.6 and Z, 2.7). The mean location of bladder hot spot was 1.6 cm anteriorly and 1.6 cm superiorly (Y, -1.6 and Z, 1.6). These hot spots were near the plane of Point A (X, 2.0 or -2.0; Y, 0; and Z, 2.0). The mean location of rectal hot spot was 1.6 cm posteriorly and 1.9 cm inferiorly (Y, 1.6 and Z, -1.9). D2 cc hot spot was affected by uterine wall thickness, uterine tandem position, fibroids, bladder fullness, bowel gas, and vaginal packing.
  
  
  CONCLUSIONS
  Because of the location of the D2 cc hot spots, larger tumors present a challenge for adequate tumor coverage with a conventional brachytherapy applicator without an interstitial implant. Additionally, anatomic factors were identified which affect the D2 cc hot spot in OARs.
authors: Department of Radiation Oncology, Hazelrig-Salter Radiation Oncology Center, University of Alabama at Birmingham, Birmingham, AL. Electronic address: rkim@uabmc.edu.
authors: Robert Y
authors: RY
authors: Kim
authors: Department of Radiation Oncology, Hazelrig-Salter Radiation Oncology Center, University of Alabama at Birmingham, Birmingham, AL.
authors: Alek F
authors: AF
authors: Dragovic
authors: Department of Radiation Oncology, Hazelrig-Salter Radiation Oncology Center, University of Alabama at Birmingham, Birmingham, AL.
authors: Alexander C
authors: AC
authors: Whitley
authors: Department of Radiation Oncology, Hazelrig-Salter Radiation Oncology Center, University of Alabama at Birmingham, Birmingham, AL.
authors: Sui
authors: S
authors: Shen
mesh_terms: D001918:Brachytherapy / Q000009:adverse effects / Q000379:methods*; D012809:Colon, Sigmoid / Q000000981:diagnostic imaging / Q000528:radiation effects; D005260:Female; D006801:Humans; D007421:Intestine, Small / Q000000981:diagnostic imaging / Q000528:radiation effects; D058958:Organs at Risk; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods; D014057:Tomography, X-Ray Computed / Q000379:methods; D001743:Urinary Bladder / Q000000981:diagnostic imaging / Q000528:radiation effects; D002583:Uterine Cervical Neoplasms / Q000532:radiotherapy*
keywords: Cervical cancer; D(2 cc); Image-guided brachytherapy; Organs at risk