Prostate cancer: image guidance and adaptive therapy.

Image-guided radiation therapy implies the use of a variety of imaging techniques in the treatment room to determine the location of target areas with the patient in the treatment position. This is particularly relevant for prostate cancer radiation therapy since the prostate gland can differ in its position within the pelvis from one treatment to another. The different imaging techniques include transabdominal ultrasound, in-room X-rays with and without the use of intraprostatic implanted fiducials, kilovoltage and megavoltage CT techniques, and even in-room MRI. The workflow and capabilities of each imaging system need to be evaluated and investigated individually.