Abstract
On the radiobiologic implications for intracavitary HDR brachytherapy of cervical carcinoma based on 3D CT imaging and Gynecological GEC-ESTRO recommendations
Brachytherapy, Vol.7(2), pp.168-168
04/2008
DOI: 10.1016/j.brachy.2008.02.237
Abstract
Purpose: Quantify radiobiologic implications—that have been limited for 2D image-based high-dose-rate brachytherapy (HDR BT) plans, employing 3D CT imaging and the gynecological GEC-ESTRO recommendations.
Methods and Materials: 2D image-based HDR BT plans were retrospectively analyzed employing 3D CT imaging for 7 patients (4 stage II patients receiving 30 Gy at 6 Gy/fx; 3 stage III receiving 28 Gy at 7 Gy/fx). All received 45 Gy EBRT at 1.8 Gy/fx. All doses were radiobiologically normalized to equivalent doses in 2 Gy fractions (EQD 2 ) applying BED. Tumor control probability parameters were separately fitted for cervical carcinoma stage II and III using pelvic disease control rates from the literature. To account for volume effect in organs-at-risk, DVH was generated and transformed into EQD 2 -based DVH. A biological uniform dose (generalized equivalent uniform dose; gEUD) was calculated. Normal-tissue-complication-probability (NTCP) values were estimated employing a classical Lyman NTCP model.
Results: The combined treatments total doses to point A (EQD 2 ) ranged from 83.4 to 84.7 Gy; median values for EQD 2, EBRT and EQD 2, BT were 44.3 and 39.8 Gy, respectively. Overall expected tumor control probabilities were 86.4% for stage II and 70.6% for stage III. The gEUD for HDR BT was 16.0 ± 8.5 Gy in the rectum and 15.2 ± 8.2 Gy in the bladder; EBRT gEUD was 70.4 ± 3.1 Gy (rectum) and 73.1 ± 1.8 (bladder). Predicted NTCP rectum for EBRT was found to be 23.3 ± 5.7% and the predicted NTCP bladder was 22.0 ± 5.8%. The predicted NTCP rectum for HDR BT was less than 0.03% and predicted NTCP bladder was less than 6x10 -8 %.
Conclusions: This study demonstrates radiobiologic evaluations are feasible when employing 3D CT imaging and GEC-ESTRO recommendations. While HDR BT delivered a comparable radiobiologic dose (39.8 Gy) to point A, the biological uniform doses to organs at risk were found to be less than 23% of those from EBRT. The predicted NTCP added by HDR BT was less than 0.03% while it was more than 22% when evaluated for EBRT. Further radiobiologic and 3D volume dosimetric studies are needed to definitively evaluate 3D image-guided HDR brachytherapy.
Details
- Title: Subtitle
- On the radiobiologic implications for intracavitary HDR brachytherapy of cervical carcinoma based on 3D CT imaging and Gynecological GEC-ESTRO recommendations
- Creators
- Yusung KimEarl NixonJoseph M ModrickSudershan K BhatiaGeraldine Mn Jacobson
- Resource Type
- Abstract
- Publication Details
- Brachytherapy, Vol.7(2), pp.168-168
- DOI
- 10.1016/j.brachy.2008.02.237
- ISSN
- 1538-4721
- eISSN
- 1873-1449
- Language
- English
- Date published
- 04/2008
- Academic Unit
- Radiation Oncology
- Record Identifier
- 9984047779902771
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