Low-dose 2.5 MV cone-beam computed tomography with thick CsI flat-panel imager.

Most of the treatment units, both new and old models, are equipped with a megavoltage portal imager but its use for volumetric imaging is limited. This is mainly due to the poor image quality produced by the high-energy treatment beam (> 6MV). A linac at our center is equipped with a prototype 2.

Observation of interfractional variations in lung tumor position using respiratory gated and ungated megavoltage cone-beam computed tomography.

Purpose: To evaluate the use of megavoltage cone-beam computed tomography (MV CBCT) to measure interfractional variation in lung tumor position.

Methods And Materials: Eight non-small-cell lung cancer patients participated in the study, 4 with respiratory gating and 4 without. All patients underwent MV CBCT scanning at weekly intervals.

Low-dose megavoltage cone-beam computed tomography for lung tumors using a high-efficiency image receptor.

We report on the capabilities of a low-dose megavoltage cone-beam computed tomography (MV CBCT) system. The high-efficiency image receptor consists of a photodiode array coupled to a scintillator composed of individual CsI crystals. The CBCT system uses the 6 MV beam from a linear accelerator.

Integrating respiratory gating into a megavoltage cone-beam CT system.

We have previously described a low-dose megavoltage cone beam computed tomography (MV CBCT) system capable of producing projection image using one beam pulse. In this study, we report on its integration with respiratory gating for gated radiotherapy. The respiratory gating system tracks a reflective marker on the patient's abdomen midway between the xiphoid and umbilicus, and disables radiation delivery when the marker position is outside predefined thresholds.

Clinical application of a repositioning scheme, using gold markers and electronic portal imaging.

Background And Purpose: To implement an on-line correction scheme based on implanted markers to reduce treatment margins in external beam radiation therapy (EBRT) of carcinoma of the prostate. In turn reduction in treatment margins reduces irradiated volumes and offers the possibility of reduced normal tissue complications or escalated target dose.

Patients And Methods: Five or six gold markers were implanted in 10 patients treated for prostate carcinoma using EBRT.