Three Dimensional Planning Significantly Improves Dose Homogeneity of Pelvic Sidewall Boost Plans Following Intracavitary Brachytherapy in Management of Cervical Carcinoma
- Resource Type
- Authors
- Arnold B. Smith; John M. Pena; John E. Bayouth; Eugene J. Endres; Theresa Deleon-mcquatters; Sandra S. Hatch
- Source
- The Cancer Journal. 8:498
- Subject
- Cancer Research
medicine.medical_specialty
business.industry
Parametrial
medicine.medical_treatment
Brachytherapy
Dose profile
Sagittal plane
Dose homogeneity
medicine.anatomical_structure
Oncology
Cervical carcinoma
Medicine
Dosimetry
Medical physics
business
Radiation treatment planning
Nuclear medicine
- Language
- ISSN
- 1528-9117
Purpose: We propose that the current practice of prescribing the parametrial boost with the pt B estimation can be made significantly more uniform aby utilizing 3D treatment planning to produce a homogenous dose profile at the reference volume and that this practice can be simply performed using an in-house forward planned IMRT. This would have several clinical ramifications including improved clinical outcome in terms of enhanced tumor control while minimizing treatment related complications. Materials and Methods: At UTMB, women with IIB-IIIB cervical carcinoma are treated with brachytherapy implants. A CT scan is performed after placement of the tandem and ovoid. The CT data sets of 20 patients and their respective 3D brachytherapy dosimetry have been analyzed. Our analysis selected the entire region within the parametrial boost that would be treated to the 95% isodose line of this field and assessed for dose homogeneity when the brachytherapy contributions were added. Custom pelvic sidewall boost plans were designed based on the brachytherapy dosimetry. This was performed using a simple and efficient method of viewing isodose clouds in 5% gradations and iteratively shielding the hot areas thereby creating uniform dose distribution. These customized plans were then contrasted to the original plans visually with comparison of the coronal, sagittal and transverse isodose clouds. DVH profiles were compared. Results and Conclusions: The forward planning IMRT successfully created a homogenous dose distribution when analyzed with 3d isodose clouds and with our forward planning technique. The distribution of dose was significantly changed based on 3d treatment planning with increased number of fractions by maintaining a 180 cGy fraction size prescribe to the 100% isodose line which corresponded to the lateral aspect of the radiation field.