2-multichannel yb

1. Prof. Yasir Bahadur
Radiation Oncologist

2.  Indication of adjuvant post hysterectomy
radiotherapy
 EBRT and/or Vaginal Brachytherapy
 Brachytherapy is delivered using vaginal
applicators (3 Fractions)
 Two types of applicators
◦ Single Channel
◦ Multiple Channel

6.  To compare the potential dosimetric advantages of
a multichannel vaginal applicator vs. a single
channel one in intracavitary vaginal HDR
brachytherapy after hysterectomy
 To evaluate the dosimetric advantage of fractional
re-planning
Y Bahadur et al., J Contemp Brachytherapy, 2015

7.  12 post hystrectomy pts
◦ CT-based HDR brachytherapy
◦ 21 Gy in 3 fractions, one fraction per week
◦ Miami 7-channels vaginal applicator
 2 treatment plans: for central channel and
multichannel loadings
◦ All plans were optimized by inverse planning
◦ DVHs analysed and compared
 Fractional re-planning for inverse planning
optimization and multichannel approach
evaluated

12. p
Multi-channel
(mean ± SD)
Single channel
(mean ± SD)
0.1574.8 ± 6.873.7 ± 7D100% (%)
CTV
0.00795.6 ± 6.794.7 ± 6D95% (%)
0.0019 + 2.37.8 +3.3Vaginal tip dose
0.00015.5 ± 0.66.5 ± 0.7D1cc (Gy)
Rectum 0.00015.1 ± 0.66.1 ± 0.7D2cc (Gy)
0.00016.3 ± 3.512.2 ± 8V70% (cc)
0.0815.2 ± 0.85.4 ± 0.9D1cc (Gy)
Bladder 0.0534.9 ± 0.85 ± 0.9D2cc (Gy)
0.771 ± 1.21.2 ± 1.5V80% (cc)

13.  The dosimetric benefit of fractional re-planning
◦ large inter-fraction variations for positioning and inconsistencies in OARs
filling

14. p
Dose difference (%)
(mean ± SD)
0.12-12.1 ± 26.9D100% (%)
CTV
0.09-9.8 ± 18D95% (%)
0.193.9 ± 13.6D1cc (Gy)
Rectum
0.291.9 ± 12.6D2cc (Gy)
0.411.4 ± 6.6D1cc (Gy)
Bladder
0.450.6 ± 6D2cc (Gy)

15.  CT-based vaginal HDR brachytherapy with
multichannel vaginal applicator provides dosimetric
advantages over single channel cylinder
 Large inter-fraction dose variations, due to marked
differences in rectum and bladder volumes and
positions

16. Thank you