New imaging techniques

Monte Carlo Study of the Dosimetry of Small-Photon Beams using Active Pixel CMOS Sensors


Radiation therapy treatments with small photon fields were first developed for treating small intracranial lesions in the late 1940 by the Swedish neurosugeron Lars Leksell. This advance gave rise to what today is known as stereotactic radiosurgery (SRS) and radiotherapy (SRT). SRS aims the radionecrosis of the target by delivering a high radiation dose in a single session. SRT in contrast is based on dose fractionation to preserve the function of normal cells and reduce toxicity. More »

Coded Apertures Phase Contrast Tomosynthesis


The aim of this project is to achieve proof of concept results in combining two imaging techniques – Coded Apertures Phase Contrast Imaging and Digital Breast Tomosynthesis.

The team at UCL has been successful in demonstrating that the Coded Apertures Phase Contrast Imaging works effectively with conventional x-ray sources and flat panel detectors available off the shelf. It provides stunning improvements of image quality showing a great enhancement of the image contrast. Based on a physical phenomenon called refraction this technique uses the ability of the x-ray to change its phase when it passes through the object. For human soft tissues, the sensitivity of the Phase Contrast Imaging can be up to 1000 times higher than that of conventional imaging methods based on absorption. More »

Protron Radiography


Proton Radiography is an imaging technique based on the measurement of the energy lost by particles after their interaction with a target. The technique will be employed as a quality control tool in proton radiation therapy (PRT) to a) verify the correct positioning of the patient and b) control the maximum depth that protons will reach within the tissue (proton range), potentially improving the accuracy in PRT by providing spatial information of the geometrical conditions encountered during the treatment. In this project, the use of C-MOS Active Pixel Sensors (APS) is proposed. More »

On-belt Tomosynthesis (ObT)

On-belt lab

2-D projection radiography is the most widely implemented method of luggage security screening for the detection of explosives and illicit materials at airports. There are two principle limitations in projection radiography. Firstly, projections of individual items within luggage are ‘stacked’ creating flattened images from which it is difficult to discriminate objects. Secondly, variations in x-ray absorption properties within the luggage can distort image information; a thin sheet of strong absorber looks the same as a thick slab of weak absorber. More »

Compton Cameras

UCL Compton camera

Over the last 10 years the UCL radiation physics group has acquired a large amount of experience and expertise in developing Compton cameras. A prototype has been built for decommissioning of nuclear power plants and has been successfully tested in situ (see references [5] and [6] in the publications list below and patent no. PCT/GB96/01497). Another prototype camera consisting of four double sided silicon microstrip detectors and a germanium detector at the back has been constructed for nuclear medicine applications. More »