Deploying early warning weapons
Molecular imaging allows for the non-invasive visualization, characterization and quantification of cellular/sub-cellular targets and pathways in living subjects. Most distinctively, it allows for biological processes to be investigated and calibrated within their own environment, rather than through in-vitro or ex-vivo cell cultures in the laboratory.
As compared to more conventional imaging techniques, which are  based on measuring differences in target density, molecular imaging uses biomarker probes to produce chemical reactions/molecular changes in the target area, and thereby alter the image.
By studying the cells of a living subject in order to determine abnormalities which form the basis of disease, the proponents of molecular imaging say it can be deployed as a far more effective weapon than traditional imaging/pathology techniques for assessment, risk profiling, evaluation and follow-up. The latter are constrained to focus on the end- or late-stage effects of molecular alterations.

A door to personalized medical care
In effect, molecular imaging allows for diagnosis of major diseases, before the onset of traditional symptoms. It is therefore expected to have a major economic impact due to savings on the burden of managing and treating a disease at a later, more advanced stage.
Molecular imaging also opens the door to personalized medical care, by revealing the specific clinical biology of the disease process in a particular patient. This is especially relevant for major cardiovascular conditions such as atherosclerosis, thrombosis, ischemia and heart failure or transplant rejection. Molecular imaging holds invaluable potential in the fight against cancers, by being able to precisely diagnose and stage tumours, assess and monitor therapies and provide extremely accurate prognoses. It also promises to become a front-line weapon in the battle against degenerative neurological diseases such as Alzheimer

As the largest teaching hospital and adult academic health sciences centre in Atlantic Canada, Capital District Health Authority, with its reputation as a centre of excellence in health research, was an obvious choice as a pilot site for Agfa HealthCare

Flat-panel technology, CT pave the way
Tomosynthesis was already known in the 1930s, as part of the family of geometric tomography techniques. However, the use of plain film meant that it was procedurally painstaking, since only one image could be acquired at a time. Even more problematic was the high dosage of radiation required to produce more imaging sections.
The emergence of computed tomography (CT) in the 1970s generated a new wave of excitement about tomosynthesis. However, progress remained dormant until the mid-1990s, when the advent of flat-panel digital detectors promised a means for tomosynthesis to acquire both technical traction and momentum.
One of the most important characteristics of flat-panel technology is the lack of distortion, since its geometry (rows and columns) is known. As a result, it is possible to interpolate reconstructions on the exact point in a tomographic layer, from which data has been recorded.
First-generation flat-panel tomosynthesis systems were, nevertheless, handicapped by speed. Experimental devices, even in the late 1990s, could only achieve four to five frames per second (FPS). However, flat panel technology has evolved since then, fuelled by increasingly sophisticated optoelectronics and back-end algorithms to interpret the data. As a result, it is now possible to acquire images at 20-30 FPS   with a radiation exposure similar to a chest X-Ray.

Different from CT
In spite of parallels, digital tomosynthesis and CT are two different techniques. Unlike the former, which typically consists of 15 images across a 15 degree arc, CT makes a full 360-degree rotation around a patient to acquire data for image reconstruction.
In digital tomosynthesis, the fewer data sets entail limited depth of field, and an inability to attain the very narrow slice widths of CT. However, given the digital processing of an image, one data set can provide for reconstruction of slices with both different depths and thicknesses; this not only saves time but radiation exposure requirements too.

Addressing limitations in slice width, but cost remains concern
Considerable efforts are underway to address the limits to slice width in digital tomosynthesis, especially in the form of more sophisticated detectors which allow higher in-plane resolution. The algorithms used to reconstruct tomosynthesis data are also more complex than CT. Together, both add to cost.

The Year of 3D Mammography
The application where digital tomosynthesis has drawn maximum attention is mammography. Indeed, digital tomosynthesis is now widely labelled as