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KMID : 0378019780210010113
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New Medical Journal
1978 Volume.21 No. 1 p.113 ~ p.118
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Calibration of Diagnostic X ray Beam Quality and Standardization of Roentgenographic Image Quality
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Abstract
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A Radiographic method for measuring the effective kilovoltages and a simplified method for standardization of roentgenographic image quality are described. The apparatus consists of a modified X ray cassette covered by a sheet of lead perforated with two rows of holes; one row is provides a reference exposure, the other row has an aluminium step wedge. The thickness of aluminium needed to give a film density which matches that of the reference exposure is called the penetration quality. The device is calibrated against a constant potential generator for which the kV values are accurately calibrated by the linear attenuation coefficiency of effective energy. For determining the effective kV of a machine, the beam is attenuated and hardened at source by means of a filter of 15cm of paraffin wax, corresponding approximately to the filteration provided by an abdomen.
For standardization of roentgenographic image quality, the concept of penetration quality is employed and it may be utilized for roentgenographic technique specification in place of kVp.
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