title: Highly conformal CT based surface mould brachytherapy for non-melanoma skin cancers of earlobe and nose.
abstract: OBJECTIVE
  Brachytherapy (BT), due to rapid dose fall off and minor set-up errors, should be superior to external beam radiotherapy (EBRT) for treatment of lesions in difficult locations like nose and earlobe. Evidences in this field are scarce. We describe computed tomography (CT) based surface mould BT for non-melanoma skin cancers (NMSC), and compare its conformity, dose coverage, and tissue sparing ability to EBRT.
  
  
  METHODS
  We describe procedure of preparation of surface mould applicator and dosimetry parameters of BT plans, which were implemented in 10 individuals with NMSC of nose and earlobe. We evaluated dose coverage by minimal dose to 90% of planning target volume (PTV) (D90), volumes of PTV receiving 90-150% of prescribed dose (PD) (VPTV90-150), conformal index for 90 and 100% of PD (COIN90, COIN100), dose homogeneity index (DHI), dose nonuniformity ratio (DNR), exposure of organs. Prospectively, we created CT-based photons and electrons plans. We compared conformity (COIN90, COIN100), dose coverage of PTV (D90, VPTV90, VPTV100), volumes of body receiving 10-90% of PD (V10-V90) of EBRT and BT plans.
  
  
  RESULTS
  We obtained mean BT-DHI = 0.76, BT-DNR = 0.23, EBRT-DHI = 1.26. We observed no significant differences in VPTV90 and D90 between BT and EBRT. Mean BT-VPTV100 (89.4%) was higher than EBRT-VPTV100 (71.2%). Both COIN90 (BT-COIN90 = 0.46 vs. EBRT-COIN90 = 0.21) and COIN100 (BT-COIN100 = 0.52 vs. EBRT-COIN100 = 0.26) were superior for BT plans. We observed more exposure of normal tissues for small doses in BT plans (V10, V20), for high doses in EBRT plans (V70, V90).
  
  
  CONCLUSIONS
  Computed tmography-based surface mould brachytherapy for superficial lesions on irregular surfaces is a highly conformal method with good homogeneity. Brachytherapy is superior to EBRT in those locations in terms of conformity and normal tissue sparing ability in high doses.
authors: Department of Radiotherapy, Medical University of Łódź
authors: Łukasz
authors: Ł
authors: Kuncman
authors: Department of Medical Physics, Regional Cancer Center, Copernicus Memorial Hospital of Łódź
authors: Sławomir
authors: S
authors: Kozłowski
authors: Department of Brachytherapy, Regional Cancer Center, Copernicus Memorial Hospital of Łódź
authors: Andrzej
authors: A
authors: Pietraszek
authors: Department of Pediatric Didactics, Medical University of Łódź, Łódź, Poland.
authors: Malwina
authors: M
authors: Pietrzykowska-Kuncman
authors: Department of Radiotherapy, Medical University of Łódź
authors: Justyna
authors: J
authors: Danielska
authors: Department of Brachytherapy, Regional Cancer Center, Copernicus Memorial Hospital of Łódź
authors: Janusz
authors: J
authors: Sobotkowski
authors: Department of Brachytherapy, Regional Cancer Center, Copernicus Memorial Hospital of Łódź
authors: Jolanta
authors: J
authors: Łuniewska-Bury
authors: Department of Radiotherapy, Medical University of Łódź
authors: Jacek
authors: J
authors: Fijuth
keywords: brachytherapy; ear; mould; nose; skin cancer