Conference proceeding
MO‐EE‐A1‐06: Tandem and Ovoids Brachytherapy for Cervical Cancer When Evaluated by High Resolution (3.0 Tesla) MRI
Medical Physics, Vol.37(6), pp.3348-3348
06/2010
DOI: 10.1118/1.3469084
Abstract
Purpose: To investigate tumor coverage and organs‐at‐risk (OAR) sparing of Manchester system based high dose rate (HDR) for different high risk (HR)‐CTV volumes. Materials and Methods: We studied 25 HDR plans of six patients with FIGO stage Ib1‐<emph IV< cervical cancer. A new plan was generated per fraction based upon the system but on MRI, utilizing titanium Fletcher‐Suit‐Delclos‐style tandem‐and‐ovoids applicators. The IR (intermediate)‐CTV, HR‐CTV, rectum, bladder, and sigmoid were delineated on MRI. Three subgroups were categorized according to HR‐CTV volumes; Non‐Bulky (< 20 cc), Low‐Bulky, and Bulky (≥ 40 cc). For each group, the percent values of D100 and D90 of HR‐ and IR‐CTV, normalized to the prescription dose (Rx), were quantified, while the percent D2cc of OAR, normalized to the dose limits. Results: We found 76%, 44%, and 68% of the plans resulted in over dose, respectively. The percent D2cc was recorded up to 143% (mean 112 ± 17%), 127% (94 ± 20%), and 181% (114 ± 34%), respectively. The D90 values of HR‐CTV in the Non‐Bulky group were on average 118% (± 21%) higher than Rx, while in the Bulky group it was 64% (± 17%), showing that HR‐CTV coverage was significantly changed for different tumor size group. The doses at Point A received on average 100% (± 3%) regardless of the tumor size. The ICRU rectum and bladder point doses showed down to 45% and 23% of their D2cc values underestimating their maximum doses. These underestimated cases were found in 36% of cases (9 plans out of 25) and 60% of cases (15 plans out of 25). Conclusion: More than 40% of the plans resulted in over doses in OAR while HR‐CTV received 118% of Rx in Non‐Bulky group. Volume optimization is expected to improve OAR sparing for all tumor sizes and in tumor coverage for small tumors.
Details
- Title: Subtitle
- MO‐EE‐A1‐06: Tandem and Ovoids Brachytherapy for Cervical Cancer When Evaluated by High Resolution (3.0 Tesla) MRI
- Creators
- Y Kim - University of IowaJ Xia - University of IowaW Sun - University of IowaS K Bhatia - University of IowaG M Jacobson - Roy J. and Lucille A. Carver College of Medicine
- Resource Type
- Conference proceeding
- Publication Details
- Medical Physics, Vol.37(6), pp.3348-3348
- DOI
- 10.1118/1.3469084
- ISSN
- 0094-2405
- eISSN
- 2473-4209
- Number of pages
- 1
- Date published
- 06/2010
- Academic Unit
- Radiation Oncology
- Record Identifier
- 9984312988902771
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