Introduction: In management of head and neck cancer, radiotherapy plays an integral role. IMRT is an established modality in radiotherapy which helps in better coverage of target volume and lower dose to critical structures which leads to lesser toxicity. Volume Modulated Arc Therapy (VMAT) offers a good alternative to IMRT with less treatment time and similar treatment outcome. In this study we have compared conformity, toxicity and treatment time of VMAT with IMRT in head and neck cancers.

Objective

1. To determine dose, plan evaluation, (monitor units) MU, optimum target volume coverage with sparing of critical structures and overall treatment time in Head & Neck cancer using VMAT
2. To review literature regarding benefit of VMAT over IMRT in head and neck cancer.

Material and Method: 60 patients of Head and Neck cancers treated with Radiotherapy using VMAT were analysed.

Result: Out of the 60 patients, 77% and 23% patients received a total dose of 70Gy and 66Gy respectively. Patients who received a total dose of 66Gy, the mean of dose receiving 95% volume was 66.5Gy. The average Monitor unit and treatment time were 993.8 and 4.2 minutes respectively. Those received 70Gy, mean of dose receiving 95% volume of PTV was 70.3Gy. Here the average Monitor unit and treatment time were 996.7 and 4.3 minutes respectively. The does received by parotid, brainstem and spinal cord were similar when compared with data available to IMRT planning.

Conclusion: VMAT provides similar conformity and toxicity as IMRT with less treatment time and less MU. This leads to a greater number of patient treatments in high volume centers.

Keywords: VMAT, Head and Neck Cancers, Treatment Time.

1. Head & neck cancer Union for International Cancer Control 2014, Review of Cancer Medicines on the WHO List of Essential Medicines.
2. Head and Neck Cancer Burden in India, by Manik Rao Kulkarni
3. Toxicity Profile of IMRT Vs. 3D-CRT in Head and Neck Cancer: A Retrospective Study, by Gopa Ghosh et al., J Clin Diagn Res. 2016 Sep; 10(9): XC01–XC03
4. Is VMAT beneficial for patients undergoing radiotherapy to the head and neck?, Radiography volume 23, issue 1 (2017).
5. Clinical experience transitioning from IMRT to VMAT for head and neck cancer, Studenski et al., Medical Dosimetry volume 38, issue 2 (2013).
6. Demographics of Head and Neck Cancer Patients: A Single Institution Experience, George S Stoyanov et.al., 2017 Jul; 9(7): e1418. Published online 2017 Jul
7. Head and Neck Tumors by John Andrew Ridge, https://www.cancernetwork.com/cancer-management/head-and-neck-tumors
8. A Comparison of IMRT and VMAT Treatment Planning for Head and Neck Cancer With NTCP/TCP Analysis, by Kryger etal, Int. J. Radiat. Oncol. Biol. Phys.
9. Volumetric intensity-modulated arc therapy vs. Conventional IMRT in head-and-neck cancer: a comparative planning and dosimetric study, by Verbakel et al., Phys., Vol. 74, No. 1, pp. 252–259, 2009, Int. J. Radiation Oncology Biol.
10. Evaluation of volumetric modulated arc therapy (VMAT) with Oncentra Master Plan for the treatment of head and neck cancer, Alvarez-Moret et al. Radiation Oncology 2010, 5:
11. Parotid gland radiation dose‐xerostomia relationships based on actual delivered dose for nasopharyngeal carcinoma, by Jingjiao Lou et al., J Appl Clin Med Phys. 2018 May; 19(3): 251–260
12. A retrospective dosimetry study of intensity-modulated radiotherapy for nasopharyngeal carcinoma: radiation-induced brainstem injury and dose-volume analysis, by Cheng-Yun Yao et.al, Radiation Oncology volume 13, Article number: 194 (2018).
13. Use of normal tissue complication probability models in the clinic, by LAWRENCE B. MARKS et al., International Journal of Radiation Oncology*Biology*Physics volume 76, issue 3-supp-S (2010).
14. Radiation Associated Brainstem Injury, by Charles Mayo et al., Int. J. Radiation Oncology Biol. Phys., Vol. 76, No. 3, Supplement, pp. S36–S41, 2010.
15. Radiation Dose–Volume Effects IN THE SPINAL CORD, by John P. Kirkpatrick et al., Int. J. Radiation Oncology Biol. Phys., Vol. 76, No. 3, Supplement, pp. S42–S49, 2010.

Dr Abani Kanta Nanda

Senior Resident, Dept. of Radiation Oncology, A.H. Regional Cancer Centre, Cuttack, India