[Oradlist] CCD vs. E/F-speed film

[Lennart Flygare]

Dear Stuart,

It is some years ago now that we abandoned film based system - I think it was in 2002 or thereabouts. We then used Kodak Insight and changed to the Schick CDR system. Following the test results from experiments with a low contrast test phantom, we then reduced exposure time 3 steps as compared with Insight film. In contradiction to what was then claimed by many, we experienced that the dynamic range of the sensor then was much smaller than film!  Since then there has been new generations of the Schick CDR wireless and we clinically experience then as both more sensitive and with a broader dynamic range than its predecessor. We today use exposures 4 steps lower than with Insight film.
We also have a Durr Vistascan Image plate system "on the side" which is some 4-5 years old by now. With that system we use exposures that are 1 step lower than Insight film.

In the local public dental healthcare the Digora Optime system is used. I can't give you as exact figures there for several reasons. Different tubes have different outputs and the clinics haven't employed as meticulous experiments before the change - also their darkroom processing wasn't as stable as at a specialist clinic neither was their care in exposure settings. The general impression however is that reduction in dose in general has been 1-2 steps as compared to Insight.

So in conclusion our experiences are: As compared to Kodak Insight: Modern Schick CDR wireless -4 steps. Durr Vistascan (4 yrs old) -1 step, Digora Optime -1, -2 steps.

Best wishes

Lennart

PS. After having written all this I note that you ask specifically for CCD. I still hope this is of some small help although the systems above are CMOS and PSP.



-------------------------------------
Lennart Flygare, Odont Dr
Senior Consultant
Dentomaxillofacial Radiology
Dept of Radiology
Sunderby Hospital
SE-971 80 Luleå
SWEDEN

tel+46-920-282931
mob: +46-70-6743858
fax:+46-920-282942
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________________________________
Från: oradlist-bounces at lists.ucla.edu [mailto:oradlist-bounces at lists.ucla.edu] För Stuart C. White
Skickat: den 3 augusti 2010 20:19
Till: Oradlist
Ämne: Re: [Oradlist] CCD vs. E/F-speed film

Thanks Allan.

Survey data does indeed points to a broad range of exposure doses with film. I do, however, have a particular interest in knowing about peoples experience in changing from E/F -speed film to CCD sensors in terms of exposure time.

Best,

Stu




On 8/3/10 11:06 AM, "Allan Farman" <agfarm01 at louisville.edu> wrote:
Hi Stu: The range of exposures that will effect an acceptable image with photostimulable phosphors and CMOS sensors is wide so it is possible for practitioners to expose the image more than with film, use the same exposure as film, or even reduce dose with these systems. Excellent latitude means that poor image quality from exposure is rare with modern digital sensors, but could indeed lead to patients being more exposed than is necessary. Studies with film based systems tend to show a remarkable range of actual exposures for specific dental radiography tasks.

Best wishes,
Allan


Allan G. Farman, BDS, PhD, MBA, DSc, Diplomate ABOMR

Prof. Radiology & Imaging Science
Univ. Louisville School of Dentistry: SUHD
501 South Preston Street,
Louisville, Kentucky 40292, USA

Tel: +1(502) 852.1241
Fax: +1(502)852.1626

>>> "Stuart C. White" <swhite at dentistry.ucla.edu> 8/3/2010 1:30 PM >>>
Hi All,

Is there any general consensus regarding the relative speeds of modern CCD sensors and E/F-speed film? For those of you who who have made the switch what is your experience?

Thanks,

Stu

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