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.

Megavoltage cone-beam computed tomography using a high-efficiency image receptor.

Purpose: To develop an image receptor capable of forming high-quality megavoltage CT images using modest radiation doses.

Methods And Materials: A flat-panel imaging system consisting of a conventional flat-panel sensor attached to a thick CsI scintillator has been fabricated. The scintillator consists of individual CsI crystals 8 mm thick by 0.