Digital Imaging in Radiography

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Questions and Answers

What is the primary purpose of a photostimulable phosphor (PSP) plate in computed radiography?

To amplify the x-ray signal and enhance image quality

To stimulate the electrons to return to a higher energy level

To absorb x-ray photons and store a latent image (correct)

To convert infrared light into visible light

What is the benefit of digital imaging in terms of storage?

It requires a dark room for image development

It requires a large storage room

It uses physical films that need to be stored

It allows for electronic storage, eliminating the need for a store room (correct)

What happens to the electrons in the PSP plate during the exposure stage?

They stay at the same energy level

They move to a lower energy level

They are eliminated from the PSP plate

They move to a higher energy level (correct)

What is the function of the CR reader in computed radiography?

To process the latent image and enhance the digital image Signup and view all the answers

What type of radiation is the PSP plate sensitive to?

X-ray photons Signup and view all the answers

What is the result of the stimulation stage in computed radiography?

The electrons return to a lower energy level Signup and view all the answers

What is the benefit of digital imaging in terms of image quality?

It produces high-resolution images Signup and view all the answers

What is the purpose of the read stage in computed radiography?

To collect the digital image data Signup and view all the answers

What is the purpose of exposure indicators in digital radiography?

To determine the optimal x-ray exposure for a specific system Signup and view all the answers

What is the role of the PACs administrator?

To maintain the storage system for images Signup and view all the answers

What is the benefit of Digital Imaging Systems?

Produce a digital image across a large range of exposure values Signup and view all the answers

What is the purpose of RIS?

To store and record patient information Signup and view all the answers

What is the benefit of using CR plates?

Convert x-ray photons to light Signup and view all the answers

What is quantum mottle?

A type of image artifact Signup and view all the answers

What is the purpose of geometric processing in digital radiography?

To invert greyscales and annotate images Signup and view all the answers

What is the benefit of PACs?

Medical staff can access images via the internet Signup and view all the answers

What is the importance of checking patient information before sending images to PACs?

To ensure correct patient identification and labelled radiograph Signup and view all the answers

What is the primary function of flooding the phosphor with white light in the CR process?

To remove residual trapped electrons and eliminate ghosting Signup and view all the answers

What is the consequence of not processing the PSP plate immediately after exposure?

25% loss of stored energy in 8 hours Signup and view all the answers

What is the primary difference between direct and indirect digital radiography?

Indirect DR uses a scintillator, while direct DR does not Signup and view all the answers

What is the purpose of the analog-to-digital conversion in digital radiography?

To convert numerical representation of x-ray beam energies to binary numbers Signup and view all the answers

What determines the contrast resolution of a digital image?

Pixel bit depth Signup and view all the answers

What is the purpose of windowing in digital imaging processing?

To expand the greyscale manually Signup and view all the answers

What is the primary function of point processing in digital imaging?

To adjust the input values of pixels to improve diagnostic quality Signup and view all the answers

What is the purpose of local processing in digital imaging?

To manipulate a selection of pixels using filters and algorithms Signup and view all the answers

Study Notes

Digital Imaging

Digital imaging is an image acquisition process that produces an electronic image that can be manipulated by a computer and displayed as a matrix of intensities.
Benefits include high image quality and resolution, image post-processing analysis, electronic storage, fast and high-quality image distribution, and image efficiency and throughput.

Types of Digital Radiography

Computed Radiography (CR)
Digital Radiography (DR) with indirect capture
Digital Radiography (DR) with direct capture

Computed Radiography (CR)

Uses a photostimulable phosphor (PSP) plate that stores latent images upon x-ray exposure.
The PSP plate is housed in a protective cassette.
Process involves getting the image, processing it at a CR image reader, and looking at it on a display.

Stages of PSP Image Formation

Expose: energy transfer from x-ray photons to the PSP atom.
Excitation: electrons in the PSP move to a higher energy level.
Trapped: electrons stay trapped at the higher energy level for a period of time.
Latent image: trapped electrons result in a latent image.

CR Reader

The machine beautifies the image using mathematical algorithms.
It puts in patient information and anatomy scanned.
The CR reader takes out the PSP plate to process the latent image.

Steps of CR Image Formation

Stimulate: the PSP plate is scanned with a low-energy laser beam to return metastable electrons to their lower energy level.
Read: the latent image is read and converted into an electrical signal.
Erase: the phosphor is flooded with white light to erase the latent image.

Image Fading

PSP sensitivity to additional exposures causes stored energy to be lost immediately after exposure.
25% of stored energy is lost in 8 hours, reducing quality.
24 hours after exposure, ghosting will be evident, and the plate must be erased.

Direct and Indirect DR

Direct capture: uses a flat-panel detector array without a scintillator.
Indirect capture: uses a thin flat-panel detector with a scintillator.

Components and Terminology of Digital Imaging

Digital images are a numeric representation of the x-ray beam energies transmitted through the patient to the IR.
Digital radiography requires analog to digital conversion, binary numbers representing transmitted photon energies, and a raw data image matrix.

Digital Image Processing Operations

Point processing: changes the input values of pixels to improve diagnostic quality.
Local processing: manipulates image data to enhance specific areas.
Geometric processing: involves flipping, rotating, magnifying, and annotating images.

Exposure Range and Dynamic Attitude

Digital imaging systems have a wide dynamic range, producing a digital image across a large range of exposure values.
Exposure latitudes for each x-ray system are important to have defined.

Exposure Indicators

Provide a standard index for radiographers to determine the adequacy of exposure for specific x-ray systems.
Displayed on the digital image as a numerical value, which must fall within an acceptable range.

PACs

Storage system for images, with patient files, medical imaging request forms, and radiology reports.
Advantages include remote access, transfer to other hospitals and clinics, and conversion to film/DVD if required.

Radiology Information System (RIS)

Database to store and record patient information, with workflow management, patient registration, and scheduling capabilities.
Also includes list and tracking capabilities, request and document scanning, reporting, and image storage.

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Description

Explore the benefits and types of digital imaging in radiography, including high-quality image acquisition, post-processing analysis, and efficient storage and retrieval.