Medicina Nuclear e Radioterapia

Comparison of ICRU and GEC-ESTRO Organ at Risk Doses in Intracavitary Brachytherapy for Carcinoma Cervix

Abstract

Joneetha Jones, Vinin NV, Shimjith Narayanan, Resmi K Bharathan, Nabeel Yahiya EK, Arun P Narendran, Greeshma KE, Shoaib Nawaz PN and Geetha Muttath

Background: In Intracavitary Brachytherapy (ICBT) for cervical cancer doses to bladder and rectum were traditionally estimated using the International Commission on Radiation Units and Measurements (ICRU) reference points and in recent years, volumetric assessment of Organ At Risk (OAR) doses is being done. This study aim to know any concordance between ICRU and GEC-ESTRO recommended OAR doses.
Materials and methods: This was a retrospective study. ICBT done in Carcinoma Cervix patients with a dosage schedule 7 Gy for 3 fractions during the period January 2017 to December 2017 were analysed. CT based ICBT plan was analysed from Treatment Planning System. From the DVH parameters OAR doses like D 0.1 cc, D1 cc and D2 cc was noted. ICRU rectal point and bladder point doses were noted from corresponding CT images. Point A doses on right and left side and EQD2 doses to point A and OAR were calculated.
Results: 165 ICBT details were analysed. Mean ICRU rectal and bladder point doses were 4.43 Gy and 3.83 Gy respectively. D2 cc dose to Rectum, Bladder and Sigmoid was 3.51 Gy, 5.23 Gy and 4.72 Gy respectively. Mean Point A dose on right and left side were 6.87 Gy and 6.91 Gy respectively and EQD2 dose to point A on right and left side were 78.5 Gy and 78.8 Gy respectively. Mean OAR doses combining EBRT and ICBT with ICRU point doses for Rectum and Bladder was 68.1 Gy and 64.1 Gy respectively and OAR doses combining EBRT and ICBT with GEC ESTRO D2 cc doses for Rectum, Bladder and Sigmoid were 62.1 Gy, 74.2 Gy and 70.2 Gy respectively.
Conclusion: Study showed no concordance between ICRU rectal and bladder point doses to GEC-ESTRO recommended OAR doses. We recommend a CT based ICBT planning with documentation of GEC-ESTRO recommended OAR doses for proper documentation of OAR doses.