Role of Body Mass Index in Intensity Modulated Radiation Therapy for Head and Neck Cancer

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Salar Q. Hasan
Edrees M. Tahir
Suha N. Aloosi


: body mass index; number of monitor units; head and neck cancer; intensity modulated radiation therapy; homogeneity index; conformity index.


Background: Radiation treatment of head and neck cancer is a difficult process because of the complex anatomy and close proximity of various organs at risk (OARs). This study aimed to assess the impact of body mass index (BMI) on the quality of the 11-field intensity modulated radiation therapy plan for head and neck cancer patients. Methods and materials: The CT scans of thirteen head and neck cancer patients were selected at the Zhianawa Cancer Center (ZCC). The Monaco treatment planning system (TPS) V5.51.10 with the Monte Carlo (XVMC) algorithm V1.6 was utilized to generate an 11F-IMRT plan and was carried out on an ELEKTAMLCi2 linear accelerator. The effect of body mass index was assessed by planning target volume (PTV) coverage, homogeneity index (HI), conformity index (CI), OARs dose, the monitor units (MUs), and delivery time. Results: the target volume was better covered as well as the dose was slightly homogeneous for overweight patients, whereas the conformity of dose distribution significantly improved in normal weight patients (P-value < 0.05). The majority of organs were better spared in the overweight group. For BMI 25 kg/m2, the dose was significantly reduced by 23.6 % and 65.2 % for the brainstem and contralateral optic nerve, respectively (P-value < 0.05). Conclusion: Increasing body mass index enhanced the overall plan quality except of conformity of dose distribution in target
volume among entire techniques. 

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