Muralidhar Mupparapu, DMD
Assistant Professor of Radiology
Department of Oral Medicine
University of Pennsylvania School of Dental Medicine
4001 Spruce St
Philadelphia, PA 19104
USA
(215) 898-8971/8972
(215) 573-8234 Fax
In August 2000, Kodak (Eastman Kodak Company, Rochester, NY) introduced its newest high speed intraoral film- "Insight" which is basically an F speed film based on the American National Standards institute (ANSI) and International organization for Standardization( ISO) specifications1,2. Just before the introduction of Kodak's insight film, Flow X-ray of West Hempstead, NY introduced their F speed film3. The introduction of these fast films has a large impact on the dose reduction to the patients.
The ANSI/ISO speed scale for dental films is as follows1.
| ISO speed range | ISO speed group letter |
|
7.0 - 14.0
S
|
C
|
|
14.0 - 28.0
S
|
D
|
|
28.0 - 56.0
S
|
E
|
|
56.0 - 112.0
S
|
F
|
According to the ANSI/ISO classification, a film with raw speed of 55 would be classified as E speed, while one with speed of 57 would be classified as F speed. The raw film Speed (S) is computed as S=0.01/Ks, where Ks is the exposure (Gray) that produces 1 optical density over base plus fog density.
There has been a two-order of magnitude reduction in the radiation exposure needed to make dental radiographs during the eight decades between 1919 and 1999.3 Considering the regular dental film made by Kodak in 1919 as a baseline, the dose to the patient was reduced to one half in 1925 with the introduction of RadiaTized film and one quarter with the introduction of the original ultra speed film in 1941 and new RadiaTized film in 1955. Around the same time, the ISO/ANSI speed group D was made available reducing the dose to the patient to another four percent and later reduced by another two percent when the E speed films were introduced by Eastman Kodak- Ektaspeed in 1981 and E plus in 1994. Overall, in the study by Farman and Farman, it was mentioned that the Flow speed film they have investigated needed only a mere 1% of the actual dose a dental film needed in 1919.3
Today both Insight film and Flow's
F speed film are routinely used by dental practitioners throught the world.
Insight film provided at least 20 line pairs/mm of resolution just as film speeds
D and E provided3. Insight performance does not appear to be different from
Ektaspeed pus or ultra-speed for caries detection (OradList communication from
Ludlow JB, University of North Carolina, June 2000) Insight maintains contrast
in progressively depleted processing solutions significantly better than Ektaspeed
plus and ultra-speed (Ludlow JB).
White SC and Yoon DC(2000)4 conducted on comparative sensitometric and diagnostic
evaluation of two speeds of films. They specifically compared Kodak Ektaspeed
films and Flow X-ray's( Flow X-ray, West Hempstead, New York, USA) new F speed
films and found that both offered equal diagnostic quality for detection of
dental caries. In fact they both met or exceeded the specifications of the American
National Standards Institute(ANSI) and American Dental Association (ADA)
In a study by Farman and Farman (2000) 3 the Flow F speed film had a spatial resolution of >20 lppm which is essentially same as the Kodak's Insight film. The introduction of these two F speed films have taken dental radiography to a new level in terms of dose minimization. Diagnostic quality is still of paramount importance in detection of lesions and the film speed should be treated circumspectly. By changing from E speed to F speed, there is an exposure reduction of atleast 20% which is substantial without losing any of the qualities of the film significantly or sacrificing the diagnostic yield5. Currently most of the Schools and practitioners are using E plus6,7 and possibly some are still using D speed films for routine intraoral radiography.
Although there is a reduction of only 20% in exposure switching from E+ to F, there is a reduction of 50- 60% when switching from D to F depending on the type and temperature of processing solutions. This is substantial dose reduction by any standards without significant compromise in the quality of the dental radiograph. Consequently for those practitioners who are not using direct digital radiography, F speed films provide an alternative for their exposure reduction needs. This is certainly not an alternative for Direct Digital Radiography (DDR) as the DDR has its own advantages for the diagnosis of routinely undetectable alterations in the loss or gain of bone density. DDR's main advantage is in having a highly sensitive recording medium like the Charge Coupled Devices, Complementary Metal Oxide Semiconductors(CMOS) or the Photostimulable Storage Phosphors(PSP).
We have certainly entered a new era of Low Dose, high yield Dentistry.
1. International Organization for
Standardization. ISO 5799-1991(E).(1991) International Standard for Photography-Direct
Exposing medical and dental radiographic film/process systems. Determination
of ISO speed and ISO average gradient, 2nd ed;
Geneva: ISO
2. American national Standards Institute. ANSI/ISO 3665-1996.(1997) American
National Standard for photography- intraoral dental radiographic film specification.
New York: American National Standards Institute.
3. Farman TT, Farman AG: Evaluation of new F speed dental X-ray film. (2000)The
effect of processing solutions and a comparison with D and E speed films. Dentomaxillofac
Radiol. 29(1) 41-5.
4. White SC, Yoon DC.(2000) Comparison of sensitometric and diagnostic performance
of two films. Compend Contin Educ Dent 21: 530-532, 534, 536.
5. Ludlow JB, Platin E, Mol A: Characteristics of Kodak Insight, an F-speed
intraoral film.(2001) Oral Surg Oral Med oral pathol oral Radiol Endod, 91(1):120-9.
6. Ludlow JB, platin E (1995) Densitimetric comparisons of ultra-speed, Ektaspeed
and Ektaspeed plus intraoral films for two processing conditions. Oral Surg
Oral Med oral pathol oral Radiol Endod. 79(1): 105-13.
7. Price C (1995) Sensitometric evaluation of a new E speed dental radiographic
film. Dentomaxillofac Radiol. 24(1): 30-6.
Copyright Dentistry On-Line 2001
First Published: December 1st 2001