Different approaches towards image-guided radiotherapy (IGRT) have been followed over the years. In the 1990s, the first electronic portal imaging devices (EPID) for linear accelerators (linacs) were developed, initially with chargecoupled device (CCD) camera optics, later using liquid ion chamber technology and now mostly based on amorphous silicon flat panels. The next step has been the introduction of room or gantrybased kilovoltage (KV) +radiograph and fluoroscopy devices, also allowing localisation by means of bony structures or fiducial markers.
Aarau has treated about 300 patients to date using the OBI, primarily for breast and prostate cancer, in the thorax region used in conjunction with gating. Indeed, Aarau is the only clinic doing gating in Switzerland. It is treating breasts (left and right side), and is also treating every lung cancer with gating and using the fluoroscopic pre-treatment setup verification on the OBI. For the very first time, this modality enables the physician to look into the patient and to analyse the target volume movement prior to treatment.
Reference: Cossman P. (2005). “Advances in Image-guided Radiotherapy – The Future is in Motion”. Head of Medical Physics, Hirslanden Klinik Aarau, Switzerland. DOI: 10.17925/EOH.2005.0.0.30