Dosimetric distribution of the surroundings of different dental crowns and implants during LINAC photon irradiation

• A phantom with metal crown and implant was designed based on the human oral cavity.
• Backscatter dose increment on mucosa depends mainly on physical density and electron density of the metal crown.
• The titanium implant will affect dose increment to bone but not to the mucosa.
• The backscatter dose will be larger for small field size if the tumor is located at a deeper region.
• QC-20 (polystyrene resin) is recommended as a shield material.

In radiotherapy of the head and neck, metal dentures or implants will increase the risk of complications such as mucositis and osteoradionecrosis. The aim of this study is to explore the back scatter effect of commercially available dental metal alloys on the mucosa and bone under 6 MV LINAC irradiation. The Monte Carlo method has been employed to calculate the dose distribution in the heterogeneous media of the designed oral phantom based on the oral cavity geometry.Backscatter dose increases up to a maximum of 53%, and is primarily dependent on the physical density and electron density of the metal crown alloy. Ceramic metal crowns have been quantified to increase backscatter dose up to 10% on mucosa. Ceramic serves as an inherent shield of mucosa. The backscatter dose will be greater for a small field size if the tumor is located at a deeper region. Titanium implants will increase the backscatter dose by 13% to bone but will not affect the mucosa. QC-20 (polystyrene resin) is recommended as a shield material (3 mm) to eliminate the backscatter dose on mucosa due to the high density metals.