Utility of a skin marker–less setup procedure using surface-guided imaging: a comparison with the traditional laser-based setup in extremity irradiation

This study aimed to assess the feasibility of a skin marker–less patient setup using a surface-guided radiotherapy (SGRT) system for extremity radiotherapy. Twenty-five patients who underwent radiotherapy to the extremities were included in this retrospective study. The first group consisted of 10 patients and underwent a traditional setup procedure using skin marks and lasers. The second group comprised 15 patients and had a skin marker–less setup procedure that used an SGRT system only. To compare the two setup procedures for setup accuracy, the mean 3D vector shift magnitude was 0.9 mm for the traditional setup procedure and 0.5 mm for the skin marker–less setup procedure (p < 0.01). In addition, SGRT systems have been suggested to improve the accuracy and reproducibility of patient setups and consistently reduce interfractional setup errors. These results indicate that a skin marker–less patient setup procedure using an SGRT system is useful for extremity irradiation.