Lead shielding has always been for reassurance more than safety. The output of an x-ray device is tightly limited (collimated) so that the direct beam outside the imaged field of view is pretty much zero - for a conventional x-ray unit, the field of view should coincide with the area that is lit up when the radiographer/tech is setting up the exposure. Irradiation outside this field is due to scatter, which if it interacts with any shielding, will likely be exiting the body, so there is close to no dose reduction. If there is lead apron overlying the chamber that sits behind the detector, and is used for exposure control, the presence of the apron could lead to increased dose (this would be pretty poor practise, but I guess it happens). Ultimately, I'm sure they've caused a lot more problems than they solve - they take time to set up, cost money to keep in good condition (the lead tends to crack and need testing and replacement) and are a good source for transmission of infection from one patient to another - most places will try to keep them clean, but that's difficult to do well. In the very early days of x-ray (50-100+ years ago), x-ray beams were largely uncollimated, less filtered, and a lead apron would have been useful to shield non target organs, as well as protecting operators who were often directly in the beam itself. Modern x-ray systems do use lower doses than historical devices - appropriate beam filtration, digital detectors, modern image processing have all made a difference; let's say to be on the generous side that we're approaching an order of magnitude reduction over the last 25 years or so I've been in medical physics. The chest x-ray and dental x-rays that come to mind for most people are actually very low dose procedures (think hours to days equivalent of naturally occurring background radiation). As an operator, it makes sense to be a decent distance away from an x-ray source, but the dose rates away from the beam are very low in 'conventional' x-ray rooms. In other situations, e.g. CT scanners, dynamic x-ray and interventional suites, the doses to the surrounding environment are higher and the beam may not be angled directly away from the operator, so more precaution is appropriate for the operators (lead aprons for the radiologists and techs are useful, lead glass screens are also used). The larger doses to the patients should be justified by the extra healthcare information provided by these types of imaging, but unnecessary repeated imaging should be avoided where possible.

The guys in Antwerp have probably got themselves the greater number crunching power, but reconstruction of tomographic images has been done using similar multi-core hardware. See the following (pdf alert) from the University of Erlangen, which uses a cluster of PS3s for a great use of commodity consumer hardware http://www.google.co.uk/url?sa=t&ct=res&cd=1&url=http%3A%2F%2Fwww.imp.uni-erlangen.de%2FIEEE%2520MIC2007%2FKnaup_Poster_M19-291.pdf&ei=t_FBSKnZKoie1gbh2Y23Bg&usg=AFQjCNG7vNGmMM2hBrYdVKbwZAJZL0oS3Q&sig2=sEdlnPROC77CZ_KJ5OOgrg .