Re: Lead Aprons in Dentistry

["Gibbs, S Julian" <s.julian.gibbs@vanderbilt.edu>]

I have read with some interest the comments pro and con use 
of lead aprons for patients undergoing dental radiography.  
This debate is really at the 1% level as compared to other 
issues:
1.  US dentists still overwhelmingly use ANSI Speed Group D 
film for intraoral radiography.  E speed film has been 
available for several years, has been demonstrated equal in 
diagnostic image quality, and reduces exposure by about 
40%. (The manufacturer claims 50%, but that is not 
substantiated in practice).
2.  US dentists still use round beams, diameter some 7 cm 
at skin entry.  Compliance with existing regs has been 
reported as excellent.  Apparatus for positive beam-film 
alignment and rectangular collimation of beam to image 
receptor has been commercially available for many years.  
Rectangular collimation reduces beam area by a factor of 
about 5.
3.  Poor darkroom practices have been frequently reported, 
resulting in needless overexposure compensated by 
underdevelopment.

Adoption of E speed film and rectangular collimation will 
reduce patient effective dose by a factor of 9-10 in those 
facilities with optimum darkroom procedures.  Cost is 
nominal ($100-200) for rectangular collimation and nothing 
for switch from D to E film (price is the same).  
Correction of darkroom procedure in those offices now 
underdeveloping could achieve even greater dose reduction.

All this says nothing about the lead apron.  However, 
dentists have been led to believe that they need not worry 
about these other factors--if they use the apron.  In a 
facility using rectangular collimation, E film, and 
rigorous darkroom QA, the lead apron is regarded as a 
prudent practice.  But it may not be essential and it 
certainly cannot be a substitute for these other 
dose-limiting practices.

Incidentally, I have often wondered why lead aprons are so 
vigorously discussed for dental radiography when they are 
rarely if ever mentioned for high-dose medical radiologic 
procedures, such as angiography.

***********************************************************
S. Julian Gibbs, DDS, PhD               Voice: 615-322-3190
Professor of Radiology                    FAX: 615-322-3764 
Dept. of Radiology & Radiological Sciences
Vanderbilt University Medical Center
Nashville TN 37232-2670 Email:s.julian.gibbs@Vanderbilt.Edu