TY - JOUR
AU1 - Campbell, John A.
AU2 - Tampas, John P.
AU3 - Gray, Donald D.
AB - Exposure Control in Cineradiography 1 John A. Campbell , M.D. , John P. Tampas , M.D. 2 and Donald D. Gray , R.T. Indiana University Medical Center 1100 West Michigan Street Indianapolis, Indiana ↵ 2 Scholar in Radiological Research of the James Picker Foundation, Department of Radiology, University of Vermont College of Medicine, Burlington, Vt. Excerpt Just as phototiming enhances the usefulness of spot-filming by eliminating exposure error, some means of assuring proper film density is a prerequisite for the broader clinical application of cineradiography. In the past, manual control of milliamperage by a millivolt monitor of the image tube current (Philips Co.) and a pre-read microammeter measuring the phototube current of a brightness-stabilizing circuit (Westinghouse) were used to establish correct cine film exposures in this work. Later, improved brightness stabilizers were employed in an attempt to maintain constant light levels for recording anatomical areas of varying opacity. While these devices, if properly used, permit one to achieve satisfactory film exposures, they are tedious to adjust, and the task of obtaining reproducible results under all conditions of cine operation requires a rather complicated procedure on the part of the radiologist. There is need for a simple-to-operate device which will assure constant film density at all film speeds, framing rates, and camera adjustments with either manual or automatic control of kilovoltage and milliamperage. Obviously, the ideal solution would be to place a photocell in the camera magazine which could monitor the light intensity passing through the shutter. The predetermined potentiometer setting of this phototube would limit the exposure time to that consistent with proper film exposure just as in spot-film phototiming. This placement of the photocell has not yet been successfully accomplished because of the physical problems incident to sampling the light intensity in the focal plane of the camera lens. Consequently, at the present time it is advisable to monitor samples of varying light intensity emerging from the center of the output phosphor and attempt to correlate these with the exposure requirements of the film in the camera. This method will be imperfect unless it compensates for the variation in the open time of the camera shutter at different filming speeds which permit the afterglow of the image-tube phosphor to contribute to the film exposure. Another shortcoming of systems which scan the full field of the output phosphor is their failure to adjust the exposure factors for changes in the field size during filming, resulting in over- or underexposure of the film whenever the field size is significantly changed by the radiologist. This paper describes an exposure meter circuitry which embodies simplicity and reliability of operation and is designed to operate on a semiautomatic basis. It offers a predetermination of proper exposure density and at the same time permits the radiologist to control manually the variable factors influencing cine exposures.
TI - Exposure Control in Cineradiography
JF - Radiology
DO - 10.1148/82.4.704
DA - 1964-04-01
UR - https://www.deepdyve.com/lp/radiological-society-of-north-america-inc/exposure-control-in-cineradiography-WIQUGpEydn
SP - 704
VL - 82
IS - 4
DP - DeepDyve
ER -