Prof. Yasir BahadurRadiation Oncologist

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

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

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

pMulti-channel

(mean ± SD)

Single channel

(mean ± SD)

0.1574.8 ± 6.873.7 ± 7D100% (%)

CTV0.00795.6 ± 6.794.7 ± 6D95% (%)

0.0019 + 2.37.8 +3.3 Vaginal 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)

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

filling

pDose difference (%)

(mean ± SD)

0.12-12.1 ± 26.9D100% (%)CTV0.09-9.8 ± 18D95% (%)

0.193.9 ± 13.6D1cc (Gy)Rectum0.291.9 ± 12.6D2cc (Gy)

0.411.4 ± 6.6D1cc (Gy)Bladder0.450.6 ± 6D2cc (Gy)

CT-based vaginal HDR brachytherapy with multichannel vaginal applicator provides dosimetricadvantages over single channel cylinder

Large inter-fraction dose variations, due to marked differences in rectum and bladder volumes and positions

Thank you