Document Detail

Quantitative evaluation by computer-based video densitometry of film response to different isotopes and fluorographic treatments.
MedLine Citation:
PMID:  3245564     Owner:  NLM     Status:  MEDLINE    
Previous investigations of fluorographic methods have generally reported the minimum level of radioactivity that can be detected for a given length of exposure or the amount of radioactivity needed to reach a given optical density value. Even when the full characteristic curve is given, comparisons with other published values are difficult or, if different lengths of exposures are used, impossible. Computer-based video densitometry was used to evaluate different fluorographic methods. Sections of polyacrylamide gels with uniform distributions of either 35S or 125I radioactivity were embedded with different fluors and used to expose X-ray film for various lengths of time. Due to its compatibility with algorithms used in densitometry, the effectiveness of various treatments was evaluated by fitting relevant parameters to a modified Hill-type equation. The two parameters that were affected by treatments were the amount of radioactivity needed to half-saturate the film (ED50, or the midpoint) and the slope at the midpoint. The relationship between length of exposure and film density was investigated. Since the ED50 values for both 35S and 125I were found to vary in a linear fashion with respect to 1/time, one can determine the ED50 for lengths of exposure not reported. A unique feature of this method of evaluating effectiveness of different treatments, therefore, is that it is possible to compare films that were exposed for different lengths of time. The method of presenting data used here overcomes many of the difficulties in comparing different fluorographic and film treatments, is compatible with the needs of computer-based densitometry, and is suggested as a useful way in which to present the relationship among isotopes, fluors, and films.
R D Rulli
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Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Analytical biochemistry     Volume:  175     ISSN:  0003-2697     ISO Abbreviation:  Anal. Biochem.     Publication Date:  1988 Nov 
Date Detail:
Created Date:  1989-05-26     Completed Date:  1989-05-26     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  0370535     Medline TA:  Anal Biochem     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  145-53     Citation Subset:  IM    
Monell Chemical Senses Center, Philadelphia, Pennsylvania 19104.
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MeSH Terms
Densitometry / methods*
Numerical Analysis, Computer-Assisted
Videotape Recording
X-Ray Film*
Grant Support
Reg. No./Substance:

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