xray viewing quality

xray viewing quality?

I dimly recall, when medical people where first
introduced to digital records, that there was tremendous
concern about image quality of XRay (films).

The diagnosticians opined that they often utilised
the most subtle of signs on the images, and that any display
system of lesser resolution, fidelity or tonal
accuracy than back lit original film would be unacceptable,
and a danger to patients.

I further recall the first "roll out" of technology
for digital xray viewing using the very finest
of high-end calibrated displays, under controlled
lighting and viewing conditions.

I now routinely see doctors viewing xrays on perfectly
normal LCD monitors from Dell, HP, Sony etc
under normal office lighting.

Does anyone know anything about the history
of all this?

I'm referring to the UK, but information
from other countries would be equally interesting.

    BugBear (intrigued)

Re: xray viewing quality?

On 29 Jan, 11:47, bugbear <bugbear@trim_papermule.co.uk_trim> wrote:
> I dimly recall, when medical people where first
> introduced to digital records, that there was tremendous
> concern about image quality of XRay (films).
>
> The diagnosticians opined that they often utilised
> the most subtle of signs on the images, and that any display
> system of lesser resolution, fidelity or tonal
> accuracy than back lit original film would be unacceptable,
> and a danger to patients.
>
> I further recall the first "roll out" of technology
> for digital xray viewing using the very finest
> of high-end calibrated displays, under controlled
> lighting and viewing conditions.
>
> I now routinely see doctors viewing xrays on perfectly
> normal LCD monitors from Dell, HP, Sony etc
> under normal office lighting.

I noticed this too, when I had a foot X-rayed (in the UK).
Some thoughts:
 - they probably took a deliberately conservative stance
 - newer LCD monitors give a finer range of greyscales
   than old ones (I remember a device that claimed to
   manage 256, but actually mapped them on to about 10)
 - does digital recording mean the images themselves are
   better, so they're no longer looking for subtle shading in
   a non-ideally exposed region of the plate?
   The doctor in A&E looking at the standard LCD isn't the
   radiographer - so it's possible that the image sent up to
   A&E has already been twiddled by the latter using a
   dedicated system in a back room, whereas with film there
   was only ever the one image.
 - When looking for subtle details (non-medical) I found it
   useful to play with the brightness and contrast, which
   means messing with keys/knobs on CRT displays.
   Maybe the doctors have found they can get the same
   effect more intuitively or efficiently just by shifting their
   viewpoint slightly up and down...
 - Conversely maybe some of the information in the image
   no longer needs to be extracted visually - e.g. to find out
   if two areas are equally dark, a read-out of the pixel value
   under the mouse pointer will probably be more accurate
   than anything you can do with a sheet of film, yet it
   clearly doesn't depend on display calibration at all.

Hth

Henry

Re: xray viewing quality?

bugbear schrieb:
> I further recall the first "roll out" of technology
> for digital xray viewing using the very finest
> of high-end calibrated displays, under controlled
> lighting and viewing conditions.
> 
> I now routinely see doctors viewing xrays on perfectly
> normal LCD monitors from Dell, HP, Sony etc
> under normal office lighting.

In Germany (and I think Europe too) there's a law which says you
must use a certified (bright, calibrated, lighting conditions)
medical monitor to view xray images to get medical evidence.

You can also use additional standard monitors, but not for
official viewing. However, sometimes you don't need perfect
viewing conditions for a first look (whether a bone is broken etc).
Later images will (have to) be reviewed in a viewing room on a
medical monitor.

Some reasons:
Not all monitors are medical grade because those are
*expensive* (around 20k€ I think, depending on model).

Current standard TFTs (non-TN) can have better image quality
compared to old (>5 years) medical ones. Viewing conditions
(calibrated, low ambient light) stay important.

Image processing improves detail visibility. You don't need
an ultra wide contrast range monitor to see everything important.
Also you can zoom in if your monitor lacks resolution.


Hendrik vdH

Re: xray viewing quality?

Hendrik van der Heijden wrote:
> bugbear schrieb:
>> I further recall the first "roll out" of technology
>> for digital xray viewing using the very finest
>> of high-end calibrated displays, under controlled
>> lighting and viewing conditions.
>>
>> I now routinely see doctors viewing xrays on perfectly
>> normal LCD monitors from Dell, HP, Sony etc
>> under normal office lighting.
> 
> Image processing improves detail visibility. You don't need
> an ultra wide contrast range monitor to see everything important.
> Also you can zoom in if your monitor lacks resolution.

yes - the use of image enhancement (which we all do, all the time
on our desktops) would appear to make super-accurate
displays unneccesary.

This idea appears not to have occured to the system
designers in the early stages of roll-out.

Possibly a conservative profession demanded that
the new system function in the same way as
the old system (film) and have the same performance.

    BugBear

Re: xray viewing quality?

On 29 Jan, 11:47, bugbear <bugbear@trim_papermule.co.uk_trim> wrote:
> I dimly recall, when medical people where first
> introduced to digital records, that there was tremendous
> concern about image quality of XRay (films).
>
> The diagnosticians opined that they often utilised
> the most subtle of signs on the images, and that any display
> system of lesser resolution, fidelity or tonal
> accuracy than back lit original film would be unacceptable,
> and a danger to patients.
>
> I further recall the first "roll out" of technology
> for digital xray viewing using the very finest
> of high-end calibrated displays, under controlled
> lighting and viewing conditions.
>
> I now routinely see doctors viewing xrays on perfectly
> normal LCD monitors from Dell, HP, Sony etc
> under normal office lighting.

I noticed this too, when I had a foot X-rayed (in the UK).
Some thoughts:
 - they probably took a deliberately conservative stance
 - newer LCD monitors give a finer range of greyscales
   than old ones (I remember a device that claimed to
   manage 256, but actually mapped them on to about 10)
 - does digital recording mean the images themselves are
   better, so they're no longer looking for subtle shading in
   a non-ideally exposed region of the plate?
   The doctor in A&E looking at the standard LCD isn't the
   radiographer - so it's possible that the image sent up to
   A&E has already been twiddled by the latter using a
   dedicated system in a back room, whereas with film there
   was only ever the one image.
 - When looking for subtle details (non-medical) I found it
   useful to play with the brightness and contrast, which
   means messing with keys/knobs on CRT displays.
   Maybe the doctors have found they can get the same
   effect more intuitively or efficiently just by shifting their
   viewpoint slightly up and down...
 - Conversely maybe some of the information in the image
   no longer needs to be extracted visually - e.g. to find out
   if two areas are equally dark, a read-out of the pixel value
   under the mouse pointer will probably be more accurate
   than anything you can do with a sheet of film, yet it
   clearly doesn't depend on display calibration at all.

Hth

Henry

Re: xray viewing quality?

bugbear schrieb:
> I further recall the first "roll out" of technology
> for digital xray viewing using the very finest
> of high-end calibrated displays, under controlled
> lighting and viewing conditions.
> 
> I now routinely see doctors viewing xrays on perfectly
> normal LCD monitors from Dell, HP, Sony etc
> under normal office lighting.

In Germany (and I think Europe too) there's a law which says you
must use a certified (bright, calibrated, lighting conditions)
medical monitor to view xray images to get medical evidence.

You can also use additional standard monitors, but not for
official viewing. However, sometimes you don't need perfect
viewing conditions for a first look (whether a bone is broken etc).
Later images will (have to) be reviewed in a viewing room on a
medical monitor.

Some reasons:
Not all monitors are medical grade because those are
*expensive* (around 20k€ I think, depending on model).

Current standard TFTs (non-TN) can have better image quality
compared to old (>5 years) medical ones. Viewing conditions
(calibrated, low ambient light) stay important.

Image processing improves detail visibility. You don't need
an ultra wide contrast range monitor to see everything important.
Also you can zoom in if your monitor lacks resolution.


Hendrik vdH

Re: xray viewing quality?

Hendrik van der Heijden wrote:
> bugbear schrieb:
>> I further recall the first "roll out" of technology
>> for digital xray viewing using the very finest
>> of high-end calibrated displays, under controlled
>> lighting and viewing conditions.
>>
>> I now routinely see doctors viewing xrays on perfectly
>> normal LCD monitors from Dell, HP, Sony etc
>> under normal office lighting.
> 
> Image processing improves detail visibility. You don't need
> an ultra wide contrast range monitor to see everything important.
> Also you can zoom in if your monitor lacks resolution.

yes - the use of image enhancement (which we all do, all the time
on our desktops) would appear to make super-accurate
displays unneccesary.

This idea appears not to have occured to the system
designers in the early stages of roll-out.

Possibly a conservative profession demanded that
the new system function in the same way as
the old system (film) and have the same performance.

    BugBear