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

Erik Gotfredsen egotfred at odont.au.dk
Thu Aug 26 04:33:10 PDT 2010


Renard numbers are rounded results of the formula

  ,
where b is the selected series value (for example b = 40 for the R40 series), and i is the i-th element of this series (with i = 0 through i = b).

source: http://en.wikipedia.org/wiki/Preferred_number#Renard_numbers

  ----- Original Message ----- 
  From: Wisam Al-Rawi 
  To: Oral Radiology Discussion Group 
  Sent: Tuesday, August 24, 2010 8:37 PM
  Subject: Re: [Oradlist] CCD vs. E/F-speed film


  I was curious to know the steps Lennart was using. Thanks for sharing the information regarding Renard scale!

  Regards,
  Wisam



  On Thu, Aug 19, 2010 at 1:55 AM, Lennart Flygare <Lennart.Flygare at nll.se> wrote:

    Dear Wisam,



    The steps I referred to was the Renard scale with a 20% increase (or 25%reduction) between each step in the following manner:

    0.10; 0,125; 10.16; 0,2; 0,25; 0.32; 0,4; 0,5; 0,64; 0,8; 1,0 and so on.





    Best wishes



    Lennart



    -------------------------------------

    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

    P  Think of the environment before printing this e-mail.


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    Från: oradlist-bounces at lists.ucla.edu [mailto:oradlist-bounces at lists.ucla.edu] För Wisam Al-Rawi
    Skickat: den 18 augusti 2010 21:53
    Till: Oral Radiology Discussion Group


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



    I realize that different x-ray machines have different x-ray output. I just want to know the exposure time for a unit instead of steps.







    -- 

    Wisam Al-Rawi, BDS, MSc, MS,
    Assistant Professor
    Admission Clinic Director
    Dept. of Oral Diagnosis and Radiology
    Case School of Dental Medicine, Cleveland, Ohio, USA
    Tel:  +1 (216) 368-0853
    Fax: +1 (216) 368-3627



    On Sat, Aug 14, 2010 at 5:35 PM, Allan G Farman <agfarm01 at louisville.edu> wrote:

    The only meaningful way to measure this would be in terms of measured dose comparisons. There are too many factors involved otherwise for the comparisons to be useful; hence percentage dose reduction is perhaps the best measure. AGF



    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



    >>> Wisam Al-Rawi <wisam.alrawi at gmail.com> 08/14/2010 05:28 PM >>>

    So far the discussion has been about reduction in percentages. Would you share the exposure parameters your school is using for Kodak Insight, CCD or CMOS sensors? (KV, mA, and time for an average adult bitewing) 

    Thank you,

    Wisam Al-Rawi





    On Wed, Aug 4, 2010 at 3:01 AM, Lennart Flygare <Lennart.Flygare at nll.se> wrote:

    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

    P Think of the environment before printing this e-mail.


----------------------------------------------------------------------------

    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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