Comparison of Intensity-modulated radiation therapy (IMRT) versus RapidArc technique in head and neck cancers – A dosimetric and clinical research

• Author Details:   
• Dimbeswar Roy
• Preety Negi ^*
• Himanshu Srivastava
• Harnoor Singh Pruthi
• Raja Sellapandiyan

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Introduction: Head and neck cancers (HNC) result in significant morbidity and mortality throughout the world, with an expected 900,000 cases and 400,000 deaths annually.  In India, head and neck cancer accounts for 30% of all cancer cases, with >65% of patients presenting with locally advanced disease.
Objectives: To compare the dosimetric (target volume coverage, dose to organs at risk (OARs), and monitor units (MUs) and clinical (mucositis and dermatitis) parameters in patients receiving IMRT versus RapidArc in HNC.
Materials and Methods: This cross-sectional, prospective study of locally advanced head and neck cancer patients (oral cavity, oropharynx, larynx, hypopharynx) was conducted on those planned for treatment with definitive concurrent chemoradiation therapy from 01.06.2023 to 31.05.2024 at Capitol Hospital, Jalandhar. These patients were randomly allocated to the IMRT or RapidArc group. The patients with previous irradiation for HNC, metastatic disease, and those who underwent surgery were excluded from the study. The target volume coverage, OARs doses, and MUs with weekly radiation-induced mucositis and dermatitis were assessed in the IMRT and RapidArc arm.  
Results: A total of 26 patients were randomized into the IMRT and RapidArc group.  There was no statistically significant difference between IMRT and RapidArc techniques in terms of target dose coverage for PTV70 and PTV59.4 Gy. The dose to OARs including mandible, lips, unilateral parotid, bilateral parotid, and spinal cord was similar for both IMRT and RapidArc techniques. The average MU to deliver a dose of 2Gy per fraction in the RapidArc technique was fewer as compared to those with the IMRT technique (p<0>
Conclusion: Our study concluded that the only significant benefit with RapidArc was much smaller total MUs required than with IMRT. Both techniques were comparable concerning target coverage and dose to OARs. However, we noticed that IMRT resulted in higher grade 3 mucositis though not statistically significant.

Keywords: Dermatitis, Head and neck neoplasms, Intensity-modulated radiotherapy, Mucositis, Organs at risk