Dosimetric evaluation of a newly designed low dose rate brachytherapy applicator for treatment of cervical cancer with extension into the lower vagina

Curtis Baker,Ali S Meigooni,Shahid B Awan,Mahesh Kudrimoti,Sharifeh A Dini

doi:10.1120/jacmp.v8i2.2400

Curtis Baker, Ali S Meigooni + Show 3 more

Open Access

https://doi.org/10.1120/jacmp.v8i2.2400

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Abstract

Currently, patients having cervical cancer with extension into the lower vagina are being treated with a combination of the Fletcher–Suit applicator, which treats the cervix, and a vaginal cylinder, which treats the lower vagina. With this method, patients receive two separate implants—a procedure that creates greater uncertainty in the dose distribution and unnecessary patient inconvenience.To reduce the uncertainty of the dose delivery and to eliminate patient inconvenience, a new applicator was designed and fabricated at the University of Kentucky for treatment of cervical cancer extending into the lower vagina. In addition, the geometric design of the new device allows for treatment of cervical cancer without extension into the lower vagina and simultaneously provides advantages relative to the commonly used Fletcher–Suit applicator.The dosimetric characteristics of this new applicator (hereafter called Meigooni applicator) were determined using experimental procedures. The measurements were performed using tissue‐equivalent phantom material (Solid Water: Gammex RMI, Middleton, WI) that was machined to accommodate the applicator and LiF thermoluminescent dosimetry chips. The applicator was loaded with C137s brachytherapy sources in a standard loading scheme. A similar experimental procedure was performed using the currently available Fletcher–Suit mini‐ovoid applicator. The results obtained with each applicator were compared with the values calculated by two commercially available treatment planning systems.The experiments showed that the Meigooni applicator allows for safe single treatment of cervical cancer that has extended into the lower vagina, eliminating the need for two separate treatment techniques. Moreover, the Meigooni applicator can function as an alternative to the Fletcher–Suit applicator for the treatment of patients with cervical cancer.PACS number: 87.53.Jw

Highlights

Much debate has arisen over the use of high-dose-rate (HDR) versus low-dose-rate (LDR) brachytherapy procedures
Many patients diagnosed with cervical cancer undergo a standard treatment regimen of 45 Gy to the pelvis delivered by external-beam radiation, followed by brachytherapy implants, and an external-beam parametrial boost.[5]. Currently, cervical cancer patients are treated using either HDR or LDR brachytherapy
The results show good agreement for point A and for the lateral vaginal mucosa

Summary

Introduction

Much debate has arisen over the use of high-dose-rate (HDR) versus low-dose-rate (LDR) brachytherapy procedures. LDR for brachytherapy implants.[1] faster treatments and shorter hospital visits are certainly advantages of the HDR treatment modality, the question of which treatment method provides the best tumor control and the fewest side effects is still uncertain.[2] Hareyama et al[3] showed that patients treated with LDR (as compared with HDR) brachytherapy for stage II cervical cancer had a better overall 5-year survival rate. As diagnoses of cervical cancer continue to rise, physicians and physicists must remain current with the rapidly changing field of radiation oncology so as to provide patients with the best possible treatment. Many patients diagnosed with cervical cancer undergo a standard treatment regimen of 45 Gy to the pelvis delivered by external-beam radiation, followed by brachytherapy implants, and an external-beam parametrial boost.[5] Currently, cervical cancer patients are treated using either HDR or LDR brachytherapy. The physician must decide on the implant and dose rate that will achieve the best isodose distribution while limiting the early and late effects of radiation

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