Title: Evaluation of Carotid Artery and Carotid Sinus doses in Early stage Carcinoma Glottis with and without bolus
Authors: Poornachandra Tejaswi, Jagannath Kunigal Puttaswamy, Lokesh Vishwanath, Poojar Sridhar, Vijay Calmuge Raghu, Saritha Sunny Pullan, Harshitha Kesergere Ramesh
Objective: To evaluate the doses received by Carotid artery and Carotid sinus in Early stage Carcinoma Glottis by 3DCRT and IMRT plans with and without bolus.
Materials and Methods: 20 patients of Early stage Carcinoma Glottis (T1/T2 N0 M0) were evaluated in this study. CT simulation was done using 3mm cuts. Target Volumes and OARs were contoured. Carotid artery and Carotid sinus were also contoured as Organs At Risk (OARs). 3DCRT & IMRT plans were generated for these patients. All patients were treated by 2D technique using 6MV photons to a total dose of 66Gy in 30fr. PTV coverage with and without bolus, V36, dose to Carotid artery and Carotid sinus were evaluated.
Results: PTV coverage with and without bolus by 3DCRT plan was 93.8% and 97.1% and by IMRT plan was 96% and 99% respectively. Average volume of Carotid artery and Carotid sinus was 7.2cc and 0.67cc. The mean dose received by Carotid artery with and without bolus by 3DCRT was 39.97Gy and 38.93Gy and by IMRT technique was 33.94Gy and 29.05Gy. The mean dose received by Carotid sinus with and without bolus in 3DCRT was 53.4Gy and 53.18Gy and by IMRT technique was 38.52Gy and 37.97Gy respectively. The V36 of Carotid artery with and without bolus by 3DCRT was 57.72% and 57.5% and by IMRT was 50.6% and 49.8%.
Conclusion: By using Conformal technique, adequate coverage of PTV is achieved. Irrespective of the technique used in Radiation therapy treatment delivery, there is always better target volume coverage with the use of bolus. Conformal techniques of treatment delivery have the advantage of delivering very minimal dose to Carotid artery and Carotid sinus. The Carotid artery and Carotid sinus must also be contoured as Organs At Risk in all cases of Head and Neck carcinomas and hence has a vital role in re-irradiation cases.
Keywords: Early stage Carcinoma Glottis, Carotid artery, Carotid sinus, 3-Dimensional Conformal Radiation Therapy (3DCRT), Intensity Modulated Radiotherapy (IMRT), Stereotactic Body Radiation Therapy (SBRT).