Photostimulable phosphor (PSP) plates are still widely used as receptors in intraoral radiography. These image receptors allow indirect digital image acquisition; more specifically, after the exposure, latent image occurs on the plate, it is then converted to a digital radiographic four image via a scanning device.
How does PSP work?
How does a cassette-based PSP system differ from conventional radiography?
What are the two types of PSP readers?
What is the PSP imaging plate?
What is digital radiographic image acquisition and processing?
What is a cassette based PSP?
What is the reflective layer of a radiographic screen?
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How does PSP work?
The patient is then exposed using the proper combination of kilovoltage peak (kVp), milliamperage seconds (mAs), and distance. The difference lies in how the exposure is recorded. In PSP, the remnant beam interacts with electrons in the barium fluorohalide crystals contained within the imaging plate. This interaction stimulates, or gives energy to, electrons in the crystals, trapping them in an area of the crystal known as the color or phosphor center. This trapped signal will remain for hours, even days, although deterioration begins almost immediately. In fact, the trapped signal is never completely lost. That is, a certain amount of an exposure remains trapped so that the imaging plate can never be completely erased. However, the residual trapped electrons are so few in number that they do not interfere with subsequent exposures.
How does a cassette-based PSP system differ from conventional radiography?
Cassette-based PSP systems differ from conventional radiography in that the cassette is simply a lightproof container that protects an imaging plate from light and handling. The imaging plate takes the place of radiographic film and is capable of storing an image formed by incident x-ray photon excitation of phosphors. The cassette-less systems using PSP technology function in a similar fashion but without the need of a cassette. During the reading process, the phosphor releases the stored light and converts it into an electrical signal, which is then digitized.
What are the two types of PSP readers?
There are two types of PSP readers: point scan and line scan. Point scan readers have an optical stage, a scanning laser beam, translation mechanics, a light pickup guide, a photomultiplier, a signal transformer/amplifier, and an analog-to-digital converter (ADC). At any point in time, only a single laser point radiates the imaging plate. Line scan readers are based on simultaneous stimulation of the imaging plate one line at a time, and with line scan readers, the acquisition of the photostimulated luminescence (PSL) occurs with a charge-coupled device (CCD) linear array photodetector. PSL refers to the emission of light from the phosphor layer after stimulation by the relevant light source. Instead of a single laser beam, there is a scanning module that contains several linear laser units and optical light collection lenses. The line scan system requires a lens array to focus each laser beam to a corresponding point on the CCD array.
What is the PSP imaging plate?
In PSP systems, the radiographic image is recorded on a thin sheet of plastic known as the imaging plate. The imaging plate consists of several layers ( Figure 4-4 ):
What is digital radiographic image acquisition and processing?
The phrase digital radiographic image acquisition and processing is used in this book to categorize the different ways of acquiring and processing digital radiographic images. One way to do this is through photostimulable phosphor (PSP) systems. These systems can be either cassette-based or cassette-less in design. This chapter introduces the process of acquiring an image using PSP technology. Key topics include technical factors, equipment selection, exposure indicators, image data recognition, and artifacts.
What is a cassette based PSP?
Cassette-based PSP systems contain a window with a barcode labelor barcode sticker on the cassette that allows the technologist to match the image information with the patient-identifying barcode on the examination request (Figure 4-5). For each new examination, the patient-identifying barcode and the barcode label on the cassette must be scanned and connected to the patient position or examination menu. In cassette-less systems, the image must be matched with the examination worklist on the computer and there will not be a paper-type sticker for the plate. The cassette-based system may also have a label such as a colored mark or sticker where applicable to indicate the appropriate orientation of the cassette in relation to the patient (Figure 4-6). When the cassette is oriented correctly, less image manipulation is required after processing. When the examination type is associated with the cassette, an automatic screen orientation of the image is built within the software. If the cassette was correctly oriented, the image will be displayed correctly; if not, the image will need to be rotated or flipped on the screen to display the image in correct anatomic orientation.
What is the reflective layer of a radiographic screen?
• A reflective layer. This is a layer that sends light in a forward direction when released in the cassette reader.
How does PSP work?
The patient is then exposed using the proper combination of kilovoltage peak (kVp), milliamperage seconds (mAs), and distance. The difference lies in how the exposure is recorded. In PSP, the remnant beam interacts with electrons in the barium fluorohalide crystals contained within the imaging plate. This interaction stimulates, or gives energy to, electrons in the crystals, trapping them in an area of the crystal known as the color or phosphor center. This trapped signal will remain for hours, even days, although deterioration begins almost immediately. In fact, the trapped signal is never completely lost. That is, a certain amount of an exposure remains trapped so that the imaging plate can never be completely erased. However, the residual trapped electrons are so few in number that they do not interfere with subsequent exposures.
How does a cassette-based PSP system differ from conventional radiography?
Cassette-based PSP systems differ from conventional radiography in that the cassette is simply a lightproof container that protects an imaging plate from light and handling. The imaging plate takes the place of radiographic film and is capable of storing an image formed by incident x-ray photon excitation of phosphors. The cassette-less systems using PSP technology function in a similar fashion but without the need of a cassette. During the reading process, the phosphor releases the stored light and converts it into an electrical signal, which is then digitized.
What are the two types of PSP readers?
There are two types of PSP readers: point scan and line scan. Point scan readers have an optical stage, a scanning laser beam, translation mechanics, a light pickup guide, a photomultiplier, a signal transformer/amplifier, and an analog-to-digital converter (ADC). At any point in time, only a single laser point radiates the imaging plate. Line scan readers are based on simultaneous stimulation of the imaging plate one line at a time, and with line scan readers, the acquisition of the photostimulated luminescence (PSL) occurs with a charge-coupled device (CCD) linear array photodetector. PSL refers to the emission of light from the phosphor layer after stimulation by the relevant light source. Instead of a single laser beam, there is a scanning module that contains several linear laser units and optical light collection lenses. The line scan system requires a lens array to focus each laser beam to a corresponding point on the CCD array.
What is the PSP imaging plate?
In PSP systems, the radiographic image is recorded on a thin sheet of plastic known as the imaging plate. The imaging plate consists of several layers ( Figure 4-4 ):
What is digital radiographic image acquisition and processing?
The phrase digital radiographic image acquisition and processing is used in this book to categorize the different ways of acquiring and processing digital radiographic images. One way to do this is through photostimulable phosphor (PSP) systems. These systems can be either cassette-based or cassette-less in design. This chapter introduces the process of acquiring an image using PSP technology. Key topics include technical factors, equipment selection, exposure indicators, image data recognition, and artifacts.
What is a cassette based PSP?
Cassette-based PSP systems contain a window with a barcode labelor barcode sticker on the cassette that allows the technologist to match the image information with the patient-identifying barcode on the examination request (Figure 4-5). For each new examination, the patient-identifying barcode and the barcode label on the cassette must be scanned and connected to the patient position or examination menu. In cassette-less systems, the image must be matched with the examination worklist on the computer and there will not be a paper-type sticker for the plate. The cassette-based system may also have a label such as a colored mark or sticker where applicable to indicate the appropriate orientation of the cassette in relation to the patient (Figure 4-6). When the cassette is oriented correctly, less image manipulation is required after processing. When the examination type is associated with the cassette, an automatic screen orientation of the image is built within the software. If the cassette was correctly oriented, the image will be displayed correctly; if not, the image will need to be rotated or flipped on the screen to display the image in correct anatomic orientation.
What is the reflective layer of a radiographic screen?
• A reflective layer. This is a layer that sends light in a forward direction when released in the cassette reader.