A novel method for skin marking in radiotherapy: first clinical use of temporary organic tattoo seal

An oil-based pen is widely used as a skin marker for identification of the isocenter and computed tomography (CT)-coordinate origin during radiotherapy. However, use of this pen has some disadvantages, including color loss and color migration. To address these problems, we have developed use of a temporary fashion tattoo (Inkbox) for skin marking. The utility and feasibility of Inkbox as an alternative to an oil-based pen were evaluated in this study. The study included patients from two centers who required skin marking for radiotherapy performed between December 2020 and March 2021. Skin markings were made with an oil-based pen or with Inkbox. The durability was recorded during daily irradiation. Skin markings with Inkbox were made in 32 patients. The total number of skin markings was 94: 64 with Inkbox and 30 with an oil-based pen. A questionnaire survey to evaluate each method was conducted among patients after radiotherapy. The median durations of marking were 16 and 4 days with Inkbox and an oil-based pen, respectively (p-value < 0.001). The survey showed that Inkbox had less impact on the daily lives of patients, including reduced color migration to clothes and less concern about disappearance of the marking. There were no adverse cutaneous side effects with Inkbox. The duration of marking with Inkbox is about 16 days, with little impact on daily life. These findings suggest that Inkbox is a potentially useful method of skin marking in radiotherapy.