2-multichannel yb
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Transcript of 2-multichannel yb
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Prof. Yasir BahadurRadiation Oncologist
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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
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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
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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
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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)
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The dosimetric benefit of fractional re-planning◦ large inter-fraction variations for positioning and inconsistencies in OARs
filling
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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)
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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
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Thank you