Effect of contrast enhanced CT scans on heterogeneity corrected dose computations in the lung.

The aim of this study was to investigate and, if possible, compensate for the effect of intravenous contrast-enhanced CT scans on the treatment planning dose distributions for lung patients. The contrast and noncontrast CT scans of 3 patients were registered, and the effect of contrast on the Hounsfield units (HU) was assessed. The effect of contrast was then simulated in the CT scans of 18 patients receiving radiotherapy of the lung by modification of the CT numbers for relevant sections of noncontrast-enhanced CT scans.

Online adaptive radiotherapy of the bladder: small bowel irradiated-volume reduction.

Purpose: To assess the potential reduction of small bowel volume receiving high-dose radiation by using kilovoltage X-ray cone beam computed tomography (CBCT) and quantized margin selection for adaptive bladder cancer treatment.

Methods And Materials: Twenty bladder patients were planned conformally using a four-field, 15-mm uniform margin technique. Two additional planning target volumes (PTVs) were created using margins quantized to 5 and 10 mm in the superior direction only.