Caution Regarding Small-Detail Object Imaging; Restrictions On Use - Siemens MAMMOMAT NovationDR Installation Instructions Manual

Caution Regarding Small-Detail Object Imaging

Restrictions on Use

Introduction
As with all digital imaging devices, there is the potential that small-detail
structures, high-contrast edge structures, and fine-line structures with a repeating
pattern could appear differently in the digital image than in an image created with
an analog device—such as screen–film system—or with another digital device
having smaller individual detector elements. For example, for a sharp-edged
object, the edges of that object may appear to have "stair-steps" when in fact the
object edge does not have such structure. This is an effect of digital undersampling.
For small-detail objects having a size on the same order of magnitude as an
individual pixel or smaller, the apparent contrast of that object can vary based on
the position relative to the individual detector element locations. For example, the
contrast of a single spherical object the same size as a pixel would have a different
appearance if the object were imaged directly overlying a detector element (highest
contrast) or placed at the intersection of four detector elements (lowest contrast).
Objects inherently smaller than individual pixels will have a lower apparent
contrast because of the digital sampling of the analog radiation intensity signal
over an area larger than the small object. In each case, a lower apparent
signal-to-noise can result in reduced visibility of such objects.
The customer is responsible for assuring that accessories used with the DirectRay
FFDM-S system do not degrade the safety of the system.
Accessories and interfacing equipment used in conjunction with the DirectRay
FFDM-S system and located outside the patient environment may be exempt from
EN60601-1. Such equipment must, however, conform to EN60601-1-1 and
therefore to standards applicable to information technology equipment such as
EN60950 and to applicable electromagnetic compatibility requirements.
February 5, 2004
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