title: Comparing a volume based template approach and ultrasound guided freehand approach in multicatheter interstitial accelerated partial breast irradiation.
abstract: OBJECTIVE
  Currently, there are two described methods of catheter insertion for women undergoing multicatheter interstitial accelerated partial breast irradiation (APBI). These are a volume based template approach (template) and a non-template ultrasound guidance freehand approach (non-template). We aim to compare dosimetric endpoints between the template and non-template approach.
  
  
  METHODS
  Twenty patients, who received adjuvant multicatheter interstitial APBI between August 2008 to March 2010 formed the study cohort. Dosimetric planning was based on the RTOG 04-13 protocol. For standardization, the planning target volume evaluation (PTV-Eval) and organs at risk were contoured with the assistance of the attending surgeon. Dosimetric endpoints include D90 of the PTV-Eval, Dose Homogeneity Index (DHI), V200, maximum skin dose (MSD), and maximum chest wall dose (MCD). A median of 18 catheters was used per patient. The dose prescribed was 34 Gy in 10 fractions BID over 5 days.
  
  
  RESULTS
  The average breast volume was 846 cm(3) (526-1384) for the entire cohort and there was no difference between the two groups (p = 0.6). Insertion time was significantly longer for the non-template approach (mean 150 minutes) compared to the template approach (mean: 90 minutes) (p = 0.02). The planning time was also significantly longer for the non-template approach (mean: 240 minutes) compared to the template approach (mean: 150 minutes) (p < 0.01). The template approach yielded a higher D90 (mean: 95%) compared to the non-template approach (mean: 92%) (p < 0.01). There were no differences in DHI (p = 0.14), V200 (p = 0.21), MSD (p = 0.7), and MCD (p = 0.8).
  
  
  CONCLUSIONS
  Compared to the non-template approach, the template approach offered significant shorter insertion and planning times with significantly improved dosimetric PTV-Eval coverage without significantly compromising organs at risk dosimetrically.
authors.affiliation: Department of Radiation Oncology, National University Cancer Institute Singapore, Singapore.
authors.forename: Vicky Y
authors.initials: VY
authors.lastname: Koh
authors.affiliation: Department of Surgery, National University Cancer Institute Singapore, Singapore.
authors.forename: Shaik A
authors.initials: SA
authors.lastname: Buhari
authors.affiliation: Department of Radiation Oncology, National University Cancer Institute Singapore, Singapore.
authors.forename: Poh Wee
authors.initials: PW
authors.lastname: Tan
authors.affiliation: Department of Radiation Oncology, National University Cancer Institute Singapore, Singapore.
authors.forename: Yun Inn
authors.initials: YI
authors.lastname: Tan
authors.affiliation: Department of Radiation Oncology, National University Cancer Institute Singapore, Singapore.
authors.forename: Yuh Fun
authors.initials: YF
authors.lastname: Leong
authors.affiliation: Centre for Quantitative Medicine, Duke NUS Graduate Medical School Singapore, Singapore.
authors.forename: Arul
authors.initials: A
authors.lastname: Earnest
authors.affiliation: Department of Radiation Oncology, National University Cancer Institute Singapore, Singapore.
authors.forename: Johann I
authors.initials: JI
authors.lastname: Tang
keywords: APBI; brachytherapy; breast cancer; interstitial; multicatheter
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