Paediatric image‐guided radiation therapy: determining and evaluating appropriate kilovoltage planar exposure factors for the Varian on‐board imager

Using an onboard kilovoltage imager to measure setup deviation in intensity‐modulated radiation therapy for head‐and‐neck patients

The purpose of the present study was to use a kilovoltage imaging device to measure interfractional and intrafractional setup deviations in patients with head-and-neck or brain cancers receiving intensity-modulated radiotherapy (IMRT) treatment. Before and after IMRT treatment, approximately 3 times weekly, 7 patients were imaged using the Varian On-Board Imager (OBI: Varian Medical Systems, Pa...

Determining appropriate timing of adaptive radiation therapy for nasopharyngeal carcinoma during intensity-modulated radiation therapy

BACKGROUND To determine appropriate timing of an adaptive radiation therapy (ART) replan by evaluating anatomic and dosimetric changes of target volumes and organs at risk (OARs) during intensity-modulated radiation therapy (IMRT) for nasopharyngeal carcinoma (NPC). METHODS Nineteen NPC patients were recruited. Each patient had repeat computed tomography (CT) scans after each five fractions a...

Quality Assurance of Varian On-board Imager

Accurate and repeatable setup of patients is a requisite in radiotherapy. In the treatment of head-and-neck tumors, accurate setup is particularly important because of the proximity of the treatment volume to critical structures such as the spinal cord, brainstem, and parotid glands. When intensity-modulated radiotherapy (IMRT) is used, proximity of this kind between the target and normal organ...

Graphical representation of the effects on tumor and OAR for determining the appropriate fractionation regimen in radiation therapy planning.

PURPOSE The authors propose a graphical representation of the relation between the effect on the tumor and the damage effect on an organ at risk (OAR) against the irradiation dose, as an aid for choosing an appropriate fractionation regimen. METHODS The graphical relation is depicted by the radiation effect on the tumor E(1) versus that on an OAR E(0). By observing the features of the E(1) vs...

Factors Influencing Radiation Quality and Radiation Exposure