Inverse planning simulated annealing for magnetic resonance imaging-based intracavitary high-dose-rate brachytherapy for cervical cancer

Kubicky, Charlotte Dai; Yeh, Benjamin M.; Lessard, Etienne; Joe, Bonnie N.; Speight, Joycelyn L.; Pouliot, Jean; Hsu, I.-Chow

doi:10.1016/j.brachy.2008.01.003

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Volume 7, Issue 3 , Pages 242-247, July 2008

Inverse planning simulated annealing for magnetic resonance imaging-based intracavitary high-dose-rate brachytherapy for cervical cancer

Charlotte Dai Kubicky
- Department of Radiation Medicine, Oregon Health and Science University, Portland, OR
- Corresponding author. Department of Radiation Medicine, Oregon Health and Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239. Tel.: +1-503-681-4180; fax: +1-503-681-4210.
Benjamin M. Yeh
- Department of Radiology, University of California, San Francisco, San Francisco, CA
Etienne Lessard
- Department of Radiation Oncology, University of California, San Francisco, San Francisco, CA
Bonnie N. Joe
- Department of Radiology, University of California, San Francisco, San Francisco, CA
Joycelyn L. Speight
- Department of Radiation Oncology, University of California, San Francisco, San Francisco, CA
Jean Pouliot
- Department of Radiation Oncology, University of California, San Francisco, San Francisco, CA
I.-Chow Hsu
- Department of Radiation Oncology, University of California, San Francisco, San Francisco, CA

Received 25 June 2007; received in revised form 17 January 2008; accepted 31 January 2008. published online 12 May 2008.

Abstract

Purpose

To develop a technique using exclusively magnetic resonance imaging (MRI) to perform dwell position identification, targets and organs at risk delineation, and to apply inverse planning dose optimization to high-dose-rate brachytherapy for cervical cancer.

Methods and materials

We included 15 consecutive women treated with high-dose-rate (HDR) brachytherapy for cervical cancer. All patients underwent MRI after placement of tandem and ring applicator containing a gadodiamide-filled dummy marker. This technique allowed direct visualization of the source pathway and precise definition of the intra-applicator source positions. For each patient, we delineated gross target volume (GTV), high-risk clinical target volume (HR-CTV), and organs at risk on MRI, according to the European Gynecological GEC-ESTRO Working Group definitions. We performed inverse planning simulated annealing (IPSA) and analyzed the dose–volume histograms with the following endpoints: D₉₀, D₁₀₀, and V₁₀₀ for GTV and HR-CTV; D0.1cc, D1cc, D2cc for bladder, rectum, and bowel; and dose at Point A.

Results

The intra-applicator source pathway was easily visualized on MRI using the gadodiamide-filled marker. IPSA provided excellent target coverage. The mean D₉₀ and V₁₀₀ for HR-CTV were 103±5% and 92±3%, respectively. IPSA provided excellent bladder sparing. D1cc and D2cc of bladder were 73±10% and 67±10%, respectively.

Conclusions

We developed a novel technique that allows direct visualization of the intra-applicator source pathway on MRI. Using this technique, we successfully performed inverse planning directly from MRI.

Keywords: Magnetic resonance imaging, Inverse planning, Brachytherapy, Cervical cancer