PET (Positron Emission Tomography) scanners create images of the distribution of positron emitters in the body of subjects under investigation. These positron emitters are attached to a variety of molecules that interact chemically within the body. Thus the PET scan has a fundamental advantage over other forms of medical imaging, such as CT scans; since it is sensitive to the functioning of biological processes. Biomarkers are involved in chemical reactions active in molecular pathways of interest for diagnosing diseases; the image will alter according to molecular changes occurring within the area of interest. Since the imaging technique operates at the sub-cellular and molecular level of the body, it is known as molecular imaging.
Every 6 minutes In Europe, someone dies of prostate cancer. These deaths are unnecessary as prostate cancer can be successfully treated if the cancer is detected at an early stage. The problem is that the standard PSA blood test used to look for prostate cancer has too many false positives; this has led to overdiagnosis and overtreatment. A reliable system is needed to follow up when there is an abnormal PSA result; this has been the focus of the TWIST project.
The promise of TWIST is a substantial improvement of images quality: a factor 2 improvement of resolution, a factor 2 reduction of background and elimination of CT scans for the attenuation maps. TWIST has used the strip SiPM detectors developed within TICAL to built gamma detectors that also measure the ‘depth of interaction’ of the gamma ray within the scintillating crystals. This allows the positioning of the detectors very close to the body without any image degradation due to parallax. Thus a PET system built using such a detector will be very compact; this increases the sensitivity and keeps the cost low.
A start-up company, Picotech, has been created by Crispin Williams (leader of WP4 of the TICAL project) in the nearby Technoparc; the goal is to produce compact PET scanners that can be used to screen for aggressive prostate cancer at a very early stage (when the tumour is 1 mm in size).
