Use of megavoltage computed tomography with image registration for high-dose rate treatment planning of an oral tongue cancer using a custom oral mold applicator with embedded lead shielding.

Purpose: A patient with a lateral oral tongue cancer was treated with high-dose rate brachytherapy using an oral applicator with embedded lead shielding making conventional simulation, using either kilovoltage computed tomography or radiographs, impossible because of scatter artifact.

Methods And Materials: Treatment simulation was accomplished using megavoltage computed tomography (MVCT) simulation on a helical tomotherapy unit. Because of difficulty in visualization of the catheters on the patient MVCT images, Velocity AI image registration software (Velocity Medical Solutions, Atlanta, GA) was used to register an MVCT of the applicator itself with the patient MVCT simulation.