We developed a “Radiation Therapy Notebook”, wherein both patients and medical staff can record an overview of the radiation therapy process and track post-treatment progress. Patients will have their individual copy of this handbook, thereby facilitating seamless bi-directional information sharing between patients and medical staff, regardless of time or location. The developed “Radiation Therapy Notebook”, was tested on 44 radiotherapy patients and 43 medical staff members involved with the patients, and the improvements, usefulness, and convenience of the notebook were examined through a questionnaire survey. Patients reported the usefulness of the notebook by stating “I was able to fully understand the details of the radiation therapy that I would receive” and “I developed a habit of careful monitoring of the treated area”. Medical staff mentioned that the “records by patients were valuable” and that “the notebook was useful for providing explanations”. The “Radiation Therapy Notebook” is useful for patients to understand their own treatment and side effects, as they can carefully and objectively observe their own symptoms and other symptoms by writing them in the notebook. Both patients and medical staff suggested the usefulness of the “Radiation Therapy Notebook”. It is hoped that this will lead to the promotion of patient-centered radiotherapy.