ABSTRACT
The posterioranterior chest radiograph remains central to the imaging and follow-up of patients with sarcoidosis. While
conventional projection radiography is the oldest of all medical
imaging tests, the technology for image acquisition has been
transformed over the last two decades. Traditional film/screen
systems for image acquisition provided images with very high
spatial resolution but were limited by a narrow exposure range.
A further problem with film as a means of image storage was
that it was physically cumbersome and suffered from image
degradation with time. The development of stimulable
phosphor plate radiography and, more recently, flat-panel
detector technology has overcome these problems. Despite a
slight quantitative reduction in the spatial resolution of the
images, these newer techniques have maintained or improved
the diagnostic quality of images (Volk et al. 2004). In fact, the
linear photoluminensce-dose response of these ‘filmless’
systems has led to a significant improvement in the visualiza-
tion of previously hidden areas (e.g. behind the mediastinum
on a frontal radiograph), as well as reducing the number of
repeat radiographs required due to under-or over-exposure.
Significantly, the ionizing radiation dose to the patient is
substantially lower with flat-panel detector digital radiography:
when compared with other techniques the effective dose is
about 50 percent that of film/screen systems and 75 percent
that of phosphor plate systems, resulting in minimal radiation
exposure (Bacher et al. 2003). Finally, the development of
patient archiving and communication systems (PACS) has
