Imaging Principles in Computed Tomography David W. Jordan and John R. Haaga Flashcards
Radiography reduces a ————- to ————- image with limited contrast, because structures that lie on top of one another are projected onto a single image.
- three-dimensional (3D) body part
- a two dimensional (2D)
The contrast can be improved (1) by using —— to enhance certain structures or by taking ——- (2), but there are limits to how well this can work.
exogenous agents
extra projections from different angles to separate the structures in the image plane
what is the advantage of CT over conventional radiography image ?
the advantage is is the improvement in image contrast that comes from using a 2D image to show an almost-2D section of the patient without the effect of overlapping structures.
The CT image is a —————- view of the patient rather than an x-ray ———-(Fig. 1-1).
The CT image is a cross-sectional view of the patient rather than an x-ray shadow of the beam passing through the body part (Fig. 1-1).
cross-sectional vs a shadow
A CT image represents a cross section of the imaged subject rather than the x-ray shadow of the anatomy, as in a conventional radiograph.
An x-ray beam is used to collect information about the tissues, but the image is not an ordinary projection view from the perspective of the x-ray tube looking toward the film or detector. The image is a crosssectional map of the x-ray attenuation of different tissues within the patient.
The typical CT scan generates a ——– image oriented in the anatomic plane of the ………dimension of the anatomy.
- transaxial
- transverse
reformating the reconstruction of the CT final image can provide us with —— or —— images, how diffrent these images are from the conventional radiographs?
Reconstruction of the final image can be reformatted to provide sagittal or coronal images; these are viewed from the same perspective as a digital radiograph, but they show thin slices of tissue rather than superimposed tissues and structures. The pixel values show how strongly the tissue attenuates the scanner’s x-ray beam compared to the attenuation of the same x-ray beam by water.
The pixel values show how strongly the tissue attenuates the scanner’s x-ray beam compared to the attenuation of the same x-ray beam by —.
The pixel values show how strongly the tissue attenuates the scanner’s x-ray beam compared to the attenuation of the same x-ray beam by water.
The CT image is produced by the process of reconstruction:
what do we mean by process of reconstruction ?
digitally combining information from x-ray projections through the patient from many different angles to produce the cross-sectional image.
