Effect of Jaw Tracking During Volumetric Modulated Arc Therapy for Facial Non-melanoma Skin Cancer.

BACKGROUND/AIM: This study aimed to analyze the dosimetric effects of jaw tracking during Volumetric Modulated Arc Therapy (VMAT) planning for facial non-melanoma skin cancer (NMSC). PATIENTS AND METHODS: This study included 50 patients with facial NMSC who underwent VMAT planning with or without jaw tracking. The target volume (TV) included the primary skin lesion with a 1-cm margin around the surface and a depth of 4 mm. A total of 55 Gy in 20 fractions was prescribed, and the plans were considered acceptable if the TV was covered by 95-105% of the isodose curve. A dosimetric comparison was performed for the volumes of the low-dose regions, which were defined as <50% of the prescription dose (V10-50%). Target coverage was evaluated using the homogeneity index (HI) and conformity index (CI). RESULTS: The patients' mean TV was 5.137 cc (range=1.03-15.89 cc). Jaw tracking resulted in mean volume reduction rates of 3.9%, 6.6% 10.6% and 13.8% for V40%, V30%, V20%, and V10%, respectively (all p<0.001). The volume change in V50% between the two groups was 2.7% (p=0.006). No significant differences were observed in HI (p=0.449) or CI (p=0.127). CONCLUSION: The application of jaw tracking during VMAT for facial NMSC is associated with a significant reduction in the volume of low dose delivered in the radiation field (V10-50%), while maintaining target coverage. Future analyses should assess whether this volume difference affects treatment-related cosmetic outcomes.

Effects of a graphene oxide-alginate sheet scaffold on rotator cuff tendon healing in a rat model.

BACKGROUND: Natural polymer scaffolds used to promote rotator cuff healing have limitations in terms of their mechanical and biochemical properties. This animal study aimed to investigate the effects of combined graphene oxide (GO) and alginate scaffold and the toxicity of GO on rotator cuff healing in a rat model. METHODS: First, the mechanical properties of a GO/alginate scaffold and a pure alginate scaffold were compared. The in vitro cytotoxicity of and proliferation of human tenocytes with the GO/alginate scaffold were evaluated by CCK-8 assay. For the in vivo experiment, 20 male rats were randomly divided into two groups (n = 10 each), and supraspinatus repair was performed: group 1 underwent supraspinatus repair alone, and group 2 underwent supraspinatus repair with the GO/alginate scaffold. Biomechanical and histological analyses were performed to evaluate the quality of tendon-to-bone healing 8 weeks after rotator cuff repair. RESULTS: The GO/alginate scaffold exhibited an increased maximum load (p = .001) and tensile strength (p = .001). In the cytotoxicity test, the cell survival rate with the GO/alginate scaffold was 102.08%. The proliferation rate of human tenocytes was no significant difference between the GO/alginate and alginate groups for 1, 3, 5, and 7 days. Biomechanically, group 2 exhibited a significantly greater ultimate failure load (p < .001), ultimate stress (p < .001), and stiffness (p < .001) than group 1. The histological analysis revealed that the tendon-to-bone interface in group 2 showed more collagen fibers bridging, tendon-to-bone integration, longitudinally oriented collagen fibers, and fibrocartilage formation than in group 1. CONCLUSION: A small amount of GO added to alginate improved the mechanical properties of the scaffold without evidence of cytotoxicity. At 8 weeks after rotator cuff repair, the GO/alginate scaffold improved tendon-to-bone healing without causing any signs of toxicity in a rat model.