The problem with the title, and the (generally well researched) article is that there is an implication that somehow our previous knowledge about the risks of radiation were wrong. The real problem is that people have an 'all or nothing' attitude to ionising radiation, where any exposure will lead to certain death/mutations/ethereal glowing. The truth is a lot more mundane, radiation is just (another) potential carcinogen that we are exposed to from a variety of sources. The more you are exposed to, the greater the risk, but the knowledge of the magnitude of exposure is key to the knowledge of risk of death.
The studies of Hiroshima and Nagasaki survivors have not been able to attribute individual cancers to radiation, rather they look at the statistics of cancer induction in the studied population, and try to work out how many of them are in excess of what one would normally see. It's a massive exercise in statistics! As a result, the estimates of the risk from unit exposure to radiation have been changing over the years, and if anything they have increased rather than the other way round (although the latest figures play down the effect of genetic factors, where radiation effects are seen in the next generation).
The stories of mass deaths from the radiation doses resulting from nuclear weapons and Chernobyl were over-hyped, and this is where the 'radiation less dangerous than once believed' headlines come from. If you were to work out the effective dose to all the people involved, which is a very difficult task, hopefully you'd get approximately the correct number of excess deaths due to radiation. The probability is (my guess) that in both cases, the large doses went to a small number of individuals. Thousands or millions more people would get lower doses that while not risk-free, were not something that was likely to kill a large number.
To add to all this, there are the problems of uncertainties of radiation risk at low doses - a number of studies have shown mild benefits, but this is a very controversial area.
At the moment, (by far) the largest radiation doses people are exposed to are from diagnostic medical exposures - x-rays, and in particular, CT scans (see the/. article on 'new super scanner' from earlier today). As with all risks, we have to balance the benefit - which in the case of a diagnostic CT scan can be huge. CT scanning anyone who has a headache isn't a good idea, though...
Whilst this scanner does have advantages over previous systems, it is an advance on previous CT (aka CaT) scanners, rather than something entirely new.
From the couple of actual facts that sneak into the story, this is a 256 'slice' scanner, compared to previously available 64 slice systems. This means that for each rotation of the x-ray tube round the patient, 256 simultaneous sets of density measurements are made. The total detector length will be in the region of 128 to 160 mm, rather than 40 mm previously.
Not knowing the intimate details of this precise scanner, I would guess that the claimed 80% dose reduction is in very limited circumstances compared to previous CTs - probably cardiac scanning, where the scan can be performed 'prospectively' rather than 'retrospectively' gated (in other words, the x-ray beam is only on during for a fraction of a cardiac beat, rather than multiple beats as before).
The other benefit seems to be the 0.27 second gantry rotation time, which is an improvement on the ~ 0.3 second rotation time before.
So overall a series of (impressive) developments, but not a totally new scanner. Toshiba also have a similar 320 slice system at this years' RSNA
BTW, IAACTP (I am a CT physicist)
Slashdot Mirror
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 .
The problem with the title, and the (generally well researched) article is that there is an implication that somehow our previous knowledge about the risks of radiation were wrong. The real problem is that people have an 'all or nothing' attitude to ionising radiation, where any exposure will lead to certain death/mutations/ethereal glowing. The truth is a lot more mundane, radiation is just (another) potential carcinogen that we are exposed to from a variety of sources. The more you are exposed to, the greater the risk, but the knowledge of the magnitude of exposure is key to the knowledge of risk of death.
/. article on 'new super scanner' from earlier today). As with all risks, we have to balance the benefit - which in the case of a diagnostic CT scan can be huge. CT scanning anyone who has a headache isn't a good idea, though...
The studies of Hiroshima and Nagasaki survivors have not been able to attribute individual cancers to radiation, rather they look at the statistics of cancer induction in the studied population, and try to work out how many of them are in excess of what one would normally see. It's a massive exercise in statistics! As a result, the estimates of the risk from unit exposure to radiation have been changing over the years, and if anything they have increased rather than the other way round (although the latest figures play down the effect of genetic factors, where radiation effects are seen in the next generation).
The stories of mass deaths from the radiation doses resulting from nuclear weapons and Chernobyl were over-hyped, and this is where the 'radiation less dangerous than once believed' headlines come from. If you were to work out the effective dose to all the people involved, which is a very difficult task, hopefully you'd get approximately the correct number of excess deaths due to radiation. The probability is (my guess) that in both cases, the large doses went to a small number of individuals. Thousands or millions more people would get lower doses that while not risk-free, were not something that was likely to kill a large number.
To add to all this, there are the problems of uncertainties of radiation risk at low doses - a number of studies have shown mild benefits, but this is a very controversial area.
At the moment, (by far) the largest radiation doses people are exposed to are from diagnostic medical exposures - x-rays, and in particular, CT scans (see the
Whilst this scanner does have advantages over previous systems, it is an advance on previous CT (aka CaT) scanners, rather than something entirely new. From the couple of actual facts that sneak into the story, this is a 256 'slice' scanner, compared to previously available 64 slice systems. This means that for each rotation of the x-ray tube round the patient, 256 simultaneous sets of density measurements are made. The total detector length will be in the region of 128 to 160 mm, rather than 40 mm previously. Not knowing the intimate details of this precise scanner, I would guess that the claimed 80% dose reduction is in very limited circumstances compared to previous CTs - probably cardiac scanning, where the scan can be performed 'prospectively' rather than 'retrospectively' gated (in other words, the x-ray beam is only on during for a fraction of a cardiac beat, rather than multiple beats as before). The other benefit seems to be the 0.27 second gantry rotation time, which is an improvement on the ~ 0.3 second rotation time before. So overall a series of (impressive) developments, but not a totally new scanner. Toshiba also have a similar 320 slice system at this years' RSNA BTW, IAACTP (I am a CT physicist)