title: Clinical feasibility of combined intracavitary/interstitial brachytherapy in locally advanced cervical cancer employing MRI with a tandem/ring applicator in situ and virtual preplanning of the interstitial component.
abstract: OBJECTIVE
  To investigate the reproducibility of virtually planned needles, changes in DVH parameters and clinical feasibility of combined intracavitary/interstitial (IC/IS) pulsed dose rate brachytherapy (PDR-BT) for locally advanced cervical cancer based on 3D MRI preplanning.
  
  
  METHODS
  Fifty-eight consecutively patients accrued in the EMBRACE study were included. Treatment was initiated with external beam radiotherapy and cisplatin. Three BT implants and MRI with the applicator in situ were performed in all patients, i.e. week 5 (BT0), week 6 (BT1) and week 7 (BT2) of the treatment. BT0 was only used for preplanning of subsequent implantations, whereas BT1 and BT2 comprised 2 equal sized fractions of PDR BT.
  
  
  RESULTS
  Based on BT0, 24 patients (41%) were selected for a combined IC/IS implant at BT1 and BT2. Patients treated with IC/IS BT had significantly larger tumours compared with patients treated with IC BT only (p<0.03). Additional time in general anaesthesia for the IC/IS component was on average 16 min. The number of preplanned virtual needles was 5.3±2.7 compared to 5.3±2.9 and 5.4±3.0 needles implanted at BT1 and BT2, respectively (p=0.72). Planned needle implantation depth was 33±15 mm compared to 30±10 mm at BT1 and 29±11 mm at BT2 (p=0.04). In the 24 patients selected for IC/IS BT both the virtual IC/IS plan (BT0) and the actually delivered plan (BT1+BT2) significantly increased D90 and D100 for HR CTV (p<0.01) and reduced D2cc for sigmoid (p<0.01) and bowel (p=0.04) compared to the optimised IC preplan (BT0). IC/IS BT was only associated with minor morbidity, which was resolved at a 3-month follow up.
  
  
  CONCLUSIONS
  Combined IC/IS BT based on full 3D MRI preplanning is clinically feasible. The virtual preplanned needle positions are reproducible at subsequent BT applications leading to significantly improved DVH parameters and a clinically feasible and fast implant procedure.
authors: Department of Oncology, Aarhus University Hospital, Denmark. Larfok@rm.dk
authors: Lars
authors: L
authors: Fokdal
authors: Kari
authors: K
authors: Tanderup
authors: Steffen Bjerre
authors: SB
authors: Hokland
authors: Lisbeth
authors: L
authors: Røhl
authors: Erik Morre
authors: EM
authors: Pedersen
authors: Søren Kynde
authors: SK
authors: Nielsen
authors: Merete
authors: M
authors: Paludan
authors: Jacob Christian
authors: JC
authors: Lindegaard
mesh_terms: D001918:Brachytherapy / Q000295:instrumentation* / Q000379:methods; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional; D053783:Magnetic Resonance Imaging, Interventional / Q000379:methods*; D009017:Morbidity; D009367:Neoplasm Staging; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D061089:Radiotherapy, Image-Guided / Q000379:methods*; D002583:Uterine Cervical Neoplasms / Q000473:pathology / Q000532:radiotherapy*