Special prosthetic device for head and neck radiotherapy based on scientific evidence

Abstract

A special prosthetic device (hereafter, special device) is thought to increase the accuracy and safety of head and neck radiotherapy; a special device has been covered by health insurance since 2016. However, the special devices currently in use differ among hospitals because the specific details about such devices have not been indicated. Additionally, dental metals are often included in the radiation field for head and neck radiotherapy. Such dental metals can cause severe oral mucositis and uncertain dose distribution due to the scattering and absorption of radiation. On the other hand, removal of dental metals prior to the initiation of radiotherapy can decrease the quality of life during radiotherapy. Removal of dental metals prior to the initiation of radiotherapy may be considered as over treatment for the resolution of these problems. Therefore, there have been discussions regarding the removal of dental metals from the radiation field. However, this issue also remains to be resolved. In the present study, we examined the changes in the dose distribution caused by dental metals and special devices to further discuss these problems based on scientific evidence. The dose intensity and range of backscatter revealed a simple linear relationship with the average atomic number of the metal. Moreover, the backscatter effect caused by common commercial dental metals disappeared at a distance of<6mmfrom the metal surface. Additionally, it was suggested that the optimal material used in special devices for head and neck radiotherapy should have a lower atomic number and physical density. Considering these results, the removal of dental metals from the radiation field seemed unnecessary. In this presentation, we also mention the further potential of a special device to be used as a tool for the prevention of oral mucositis.