GYN PosterDelineating the Relationship between Point A Prescription Dose and Pelvic Lymph Node Doses in Intracavitary High-Dose Rate (HDR) Brachytherapy Treatment of Cervical Cancer
Section snippets
Purpose
This study aims to define the relationship between prescription dose and the dose delivered to various pelvic lymph node groups during HDR brachytherapy treatment of cervical cancer. Carcinoma of the cervix is a common cause of cancer in women worldwide. Approximately 500,000 new cases are reported each year, most of which occur in developing countries. Pelvic lymph node metastasis is an extremely important prognostic factor in cervical cancer. Therefore, it is critical to ensure lymph nodes
Materials and Methods
Treatment data from 16 patients with varying stages of cervical cancer who underwent CT guided HDR brachytherapy was reviewed. Patients underwent anywhere from 1-5 treatment sessions, and pelvic lymph nodes were contoured for each session with a viable CT scan. The obturator, presacral, common, external and internal iliac lymph nodes were contoured. 50 sessions were analyzed in total. Presacral and common iliac doses were only obtained for 45 sessions because five CT scans did not extend
Results
Mean point A doses were Bil 5.92 Gy ± 0.58, L 5.93 ± 0.59, and R 5.92 ± 0.59. Mean normalized D90 values for the various lymph node groups were Obturator: Bil 19.8% ± 4.5, L 20.5 ± 4.4, and R 20.2 ± 5.2; External Iliac: Bil 9.5% ± 2.9, L 10.0 ± 3.0, and R 9.5 ± 3.0; Internal Iliac: Bil 12.2% ± 3.5, L 12.1 ± 3.4, and R 12.9 ± 4.7; Common Iliac: Bil 4.3% ± 1.6, L 4.3 ± 1.6, and R 4.3 ± 1.7. The presacral nodal group was not divided into left and right sides. The mean normalized D90 value for the
Conclusions
These relationships can serve as a useful tool for evaluating lymph node dosage during HDR brachytherapy of cervical cancer, particularly in healthcare facilities lacking the technology for 3D image guided brachytherapy. . Mean of D90 values for pelvic lymph node groups normalized as a percentage of the corresponding point A dose for 50 brachytherapy applications.Nodal group Bilateral D90 (% of point A) Left sided D90 (% of point A) Right sided D90 (% of point A) Obturator 19.8 ± 4.5 20.5 ± 4.4 20.2 ± 5.2