Dosimetry Effect of Different Metal Dentures on Gross Tumor Volume of Patients with Tongue Cancer
Objective To investigate the dosimetry impact of different metal dentures on gross tumor volume(GTV)in patients with tongue cancer undergoing radiotherapy.Methods A phantom composed of bolus,teeth,and standard solid water was established.CT images of the phantom with three types of metallic dental prostheses,nickel-chromium alloy,zirconium dioxide,and cobalt-chromium alloy,were obtained.GTVs of different depths with a radius of 1.9 cm were set behind the dentures.An single beam open-field plan and volumetric modulated arc therapy(VMAT)plan were designed.The dose distribution to the target area with different metal dentures was calculated and analyzed to determine the impact of each prosthesis on dosimetric parameters.Results Compared with normal teeth,the calcu-lation deviation of maximum dose(Dmax)and average dose(Dmean)caused by different metal dentures were less than 3％,and zirconia dentures had the greatest effect on target dose.The maximum dose deviation caused by metallic prostheses occurred at a GTV depth of 5.9 cm.Conclusions CT artifacts generated by metal dentures can affect the target dose of radiotherapy for tongue cancer.It is necessary to consider removing the patient's dentures or using the artifact correction algorithm to adjust the localization CT ima-ges when the GTV is close to the metal dentures.
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