Assessment of PTV variations with and without shoulder retractor in head and neck radiotherapy: hospital-based retrospective study

Accurate delineation of target volumes is essential in head and neck radiotherapy to enhance tumor control and reduce normal tissue toxicity. The effect of shoulder retraction on planning target volume (PTV) variations, treatment replanning, and clinical skin toxicity remains unclear. This study aimed to retrospectively evaluate the differences in planning target volume (PTV) variations, the frequency of treatment replans, and the incidence of clinical skin toxicity among head and neck cancer patients receiving radiotherapy, specifically comparing those treated with shoulder retraction to those without it. We have analyzed data from 100 patients (50 with shoulder retractor, 50 without) treated at our institution from March 1 to September 30, 2024. All our patients were simulated and contoured by the same radiation oncologist and treated using a 4D-Couch with IMRT plans created by a single physicist. An online review of the setup was performed for the first three fractions, followed by weekly offline reviews to minimize observer variability. The PTV variations in rotation, roll, and pitch, as well as the number of replans and clinical skin toxicity, were compared between the two groups. Follow-up for radiation-related adverse effects was conducted weekly, and severity was graded using the Common Terminology Criteria for Adverse Events (CTCAE). Arm 1 (shoulder retractor) showed lower mean variations in rotation, roll, and pitch compared to Arm 2 (no shoulder retractor), with statistically significant differences. These values for Arm 1 were Mean: (0.02, 0.6, 0.34, 0], Median: (0.1, 0.8, 0.2, 0) and Standard Deviation: (0.25884353, 0.40000001, 0.48989795, 0); and for Arm 2 were Mean: (0.32, 0.72, 1.02, 1.2), Median: (0.5, 0.4, 1, 1) and Standard Deviation: (0.60827631, 1.01980393, 0.34307765, 0.4472136). Skin toxicity was also reduced in Arm 1, with 12 patients experiencing Grade 3 toxicity compared to 32 in Arm 2. Additionally, Arm 1 had no treatment gaps due to skin toxicity, unlike Arm 2, which had 11 gaps. An additional parameter of improvement of exposure of the cervical spine was also observed in Arm 1. These values were found to be statistically significant; and the patients in general reported the device as comfortable. Our study supports the use of shoulder retractors in head and neck radiotherapy, demonstrating improved PTV stability and reduced skin toxicity. Additionally, rotation correction was done on the 4-D couch, but 6-D couch achieves better roll and pitch matching and is, thus, better for the setups. However, further research is needed to assess long-term benefits and the patient 's quality of life. (author)