Utilizing skin sparing technique in HN VMAT treatment planning

This study aims to demonstrate a specific treatment planning method and its effectiveness of sparing high dose to superficial skin for head and neck volumetric-modulated arc therapy (VMAT) treatments. A total of 10 patients with bilateral disease encompassing superficial neck nodes were planned as VMAT. Standard VMAT plans were created for each patient per written directive from physician, including target prescriptions, normal structure goals, and plan parameters. After these plans were created, low isodose levels were converted into dose structures, which are used to create a new skin sparing (SS) structure. With the new SS structure made, the original plan was copied to create a new SS plan. The new SS plan was re-optimized utilizing the newly created SS structure to help in decreasing dose to the superficial regions on the skin surface. The result of this treatment planning technique, comparing SS plans to original nonskin sparing (NSS) plans, provides a reduced dose of 10% to 15% to the skin surface in all cases. Although this technique reduces the dose to the skin, it can also reduce the dose to treatment volumes. Depending on physician intent, diagnosis, and disease, this method should only be used when the skin is not at risk, otherwise it could potentially cause underdosing to the disease site. All SS plans were considered clinically acceptable and provided adequate coverage to planning target volume (PTV), while reducing unwarranted high dose to superficial skin tissue.