Context: Dosimetric evaluation of bladder and rectal Radiation dose in Ca Cervix patients using  CT planning using Iridium 192 and Cobalt 60 in HDR Brachytherapy- Single Institutional Experience

Aim: To compare the doses of Bladder and Rectal radiation dose in advanced cases of Carcinoma Cervix, using CT simulation iridium 192, Cobalt-60 as source in HDR Brachytherapy, two arm study.

Material and Methods:  This is a Comparative descriptive study in single institution done in 60 eligible patients of age 30-60 years who had Squamous Cell Carcinoma of cervix completed EBRT and slated for Brachytherapy of all stages upto III B during the period of, January 2010 to August 2010 – Arm A, January 2016 to June 2016 – Arm B. All patients were treated with conventional EBRT 50 Gy in 2 Gy/# for 5 days a week/25# followed by 8 Gy in 2# for  ICA application, using iridium 192 (Arm A) Cobalt 60 (Arm B) Treatment completed within maximum period of 10 – 12 weeks.

Intracavitary Brachytherapy and Dosimetry: Orthogonal X-ray and CT simulation was taken and Point A and point B Bladder and rectal were studied after treatment was carried out using iridium 192 as source Arm A. CT simulation of 3mm thickness was obtained, 5cm from top of uterine tandem superiorly and to the level of 2cm below vaginal introitus inferiorly (From Barnard institute of Radiology). HRCTV, Rectum and Bladder were contoured. Treatment planning was carried out using HDR Plus treatment planning system. Point A and point B, Bladder and rectal doses were studied after treatment was carried out using cobalt-60 HDR remote after loading machine for Arm B.

Results: Out of the 60 patients the average dose received by Point A, Point B, Bladder and Rectal points was within tolerable limits. Early side effect of Organ at Risk, Bladder and Rectum was calculated with BED which is acceptable.

Arm A

Average doses received by Poin A - 86.7 (LDR equivalent) Bladder-D2 Volume Rectal D2 Volume

Arm B

Average dose received by Point A – 74.1 Gy, Point B – 56.8 Gy, Bladder – D2 Volume : 7.5 Gy, Rectum D2 Volume: 6.7 Gy. Response assessment was done immediately and it was complete response in 98% with minimal residual disease in a single patient. Toxicity assessment of Bladder and Rectum were done. Only Grade 1 and Grade 2 reactions were present in both. Patients are under follow up study to assess disease free survival rate and   late complications of bladder and rectum.

Conclusion: CO 60 HDR Brachytherapy is not producing bladder and rectal complications and equally shows results on par with Iridium.With long half life it is economical to run CO60 HDR Brachytherapy in treating Carcinoma Cervix.

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Dr Madhumathi.S

Senior Assistant Professor, Department of Radiotherapy