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. The treatment plan was manually optimized to prescribe 4Gy/fraction to the gross tumor volume. RESULTS: The patient tolerated the treatment well, with no evidence of disease 6 months after treatment. Thermoluminescent dosimeter measurements showed that the shielding reduced the dose by up to 90%, depending on the location of the thermoluminescent dosimeter. While the patient was treated using dose distributions calculated in a homogeneous medium (Task Group-43), an approximation of the true dose distributions was retrospectively calculated using Acuros (Varian Medical Systems Inc., Palo Alto, CA), which accounts for heterogeneities in the patient. DISCUSSION: Use of the MVCT with image registration allowed treatment planning in the presence of lead shielding. Dose-volume histograms showed that recalculation of the dose using heterogeneity correction did not affect the dose to the gross tumor volume, but that the dose to normal structures (maxilla and mandible) was reduced by the lead shielding. CONCLUSION: The use of MVCT and image registration allows for optimized planning in the presence of shielding, which would not be possible with conventional kilovoltage computed tomography.

A systematic review of oral fungal infections in patients receiving cancer therapy.

PURPOSE: The aims of this systematic review were to determine, in patients receiving cancer therapy, the prevalence of clinical oral fungal infection and fungal colonization, to determine the impact on quality of life and cost of care, and to review current management strategies for oral fungal infections. METHODS: Thirty-nine articles that met the inclusion/exclusion criteria were independently reviewed by two calibrated reviewers, each using a standard form. Information was extracted on a number of variables, including study design, study population, sample size, interventions, blinding, outcome measures, methods, results, and conclusions for each article. Areas of discrepancy between the two reviews were resolved by consensus. Studies were weighted as to the quality of the study design, and recommendations were based on the relative strength of each paper. Statistical analyses were performed to determine the weighted prevalence of clinical oral fungal infection and fungal colonization. RESULTS: For all cancer treatments, the weighted prevalence of clinical oral fungal infection was found to be 7.5% pre-treatment, 39.1% during treatment, and 32.6% after the end of cancer therapy. Head and neck radiotherapy and chemotherapy were each independently associated with a significantly increased risk for oral fungal infection. For all cancer treatments, the prevalence of oral colonization with fungal organisms was 48.2% before treatment, 72.2% during treatment, and 70.1% after treatment. The prophylactic use of fluconazole during cancer therapy resulted in a prevalence of clinical fungal infection of 1.9%. No information specific to oral fungal infections was found on quality of life or cost of care. CONCLUSIONS: There is an increased risk of clinically significant oral fungal infection during cancer therapy. Systemic antifungals are effective in the prevention of clinical oral fungal infection in patients receiving cancer therapy. Currently available topical antifungal agents are less efficacious, suggesting a need for better topical agents.