The recent advent of highly conformal three-dimensional radiotherapy techniques and Intensity Modulated Radiotherapy now allows higher radiation doses to be delivered. It is well-documented that the prostate is susceptible to both interfraction and intrafraction movements due to various physiological processes. Therefore there has been a recent general consensus that good immobilisation and electronic portal imaging is no longer sufficient to ensure accurate treatment verification. This idea has led to the concept of image-guided radiotherapy, which includes modalities such as cone-beam computed tomography and ultrasound to localise the prostate prior to treatment.There has been considerable research undertaken to determine the effectiveness of each of the image guided modalities and these studies have identified the benefit and limitations of each modality. Ultrasound is a non-invasive technique using a suprapubic ultrasound probe, which seems to be quite promising in terms of cost and time. However until large scales studies are performed which demonstrate the value of using ultrasound localisation, as an alternative to electronic portal imaging, it is likely that current practice will remain unchanged.
Verification of setup errors in external beam radiation therapy using electronic portal imaging