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“Display Technology, NDT/QA testing Procedures and Standards”
by Nasir Zaidi of SC Inc., Burbank CA.
Control
the Lighting Condition Under Which Radiographs and Images are Viewed and
Interpreted:
Spectra Candela PhoRad
Photometer model SC-820 is essential for quality assurance of medical
imaging at Diagnostic Imaging departments in hospitals and clinics.
This innovative, hand-held radiographic optical instrument is a completely
portable, battery powered auto ranging photometer designed to measure light intensity of
medical diagnostic imaging displays, film
viewing boxes, viewing port, image monitors, collimator light field and etc.
Photometer reads directly in candelas per meter squared (cd/m2) and
nits.
Also to optimize image contrast, it also measures the ambient
background illumination falling on the viewer surface in lux (lx), as set forth in the new standards
outlined in the Standard
Practice for Radiographic Examination ASTM E-1742-08. (more)
Internationally
Accepted Test Pattern to analyze Diagnostic Imaging Displays:
The
Society of Motion Picture and Television Engineers (SMPTE) has specified
test pattern for display monitors. The SMPTE pattern has among other things
11 different grey scale areas to measure the luminance values of the
display.
SMPTE
Recommended Practice. Specifications for Medical Diagnostic Imaging Test
Pattern for Television Monitors and Hard-Copy Recording Cameras, RP 133 -
1991.
*Scope:
This Practice describes the format, dimensions, and contrast required to
make diagnostically significant measurements of the display and camera
system resolution for both digital and analog monochrome signal sources. The
practice provides users of medical diagnostic imaging systems with a
comprehensive test pattern for day-to-day operational checks and adjustments
of focus, brightness and contrast , resolution response, mid-band streaking,
uniformity, and linearity of viewing monitors and hard copy recordings. This
practice is not intended to create a standard for image characteristics such
as resolution, geometry and linearity, uniformity, phosphor defects, etc. However,
use of the pattern is encouraged as an appropriate tool for evaluating the
measurement and specification of such image characteristics.
*SMPTE
Recommended Practice RP 133-1991
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