In each blank, try to type in the
word that is missing. If you've
typed in the correct word, the
blank will turn green.
If your not sure what answer should be entered, press the space bar and the next missing letter will be displayed. When you are all done, you should look back over all your answers and review the ones in red. These ones in red are the ones which you needed help on. Question: Physical basis for the CR image is the IP detector, which is made of a photostimulable (PSP) (3 steps):Answer: After X-ray exposure, latent image is formed,
Laser beam extracts image information signal,
Signal is digitized and sent to a for preprocessing.
Question: Two categories of flat panel DR :Answer: Indirect TFT and TFT. Question: Indirect and direct are on the type of x-ray absorber used, what do each use?Answer: uses phosphor, direct uses a photoconductor. Question: Systems that use phosphor (indirect detectors) and systems that use (direct) differ by converting x-rays to electrical how?
Answer: phosphor (indirect)- convert x-ray energy into electrical through an intermediate stage of light photons, photoconductors (direct) convert energy energy directly into electrical charge without the stage. Question: 2 of indirect digital detectors?Answer: charged coupling device (CCD) digital detector, and the flat-panel thin film transistor (TFT) digital detector. (difference between them is technical factors on how to convert to electrical) Question: CCD digital detector is based on an _____ conversion process and uses a _______ to convert light to electrical signal.Answer: , CCD chip Question: Which detector is not classified as a flat-panel digital detector but is commercially?Answer: Question: 4 main components of a CCD ?Answer: x-ray , scintillator, light optics, the CCD. (which is a sensor chip.. or many...) Question: What does the CCD (sensor ) do?Answer: captures the , and is also an electrical charge readout device. Question: screen does what in CCD detectors? ****Answer: detects x-rays and converts them into Question: An indirect flat-panel (TFT) digital detector uses several components to convert x-rays into that is subsequently converted into electrical charges, these components are:Answer: x-ray scintillator (conversion usually cesium iodide or gradolinium), an amorphous silicon (a-Si) photodiode flat panel layer, with a thin-film transistor (TFT) (for reader of the electrical charges by the photodiode) Question: Scintillator layer used in indirect flat-panel (TFT) is usually either ___________ or ________.Answer: cesium (Csl) or gradolinium oxysulfide (Gd2O2S) Question: (indirect flat panel (TFT) detectors) ______ crystals are deposited in a needle like fashion (_______ phosphor) and run in the direction of the x-ray beam.Answer: cesium iodide (Csi) crystals are deposited in needle like , (structured phosphors) Question: (indirect flat panel (TFT) detectors) ______ crystals are deposited powdered particles (_______ phosphor).Answer: gradolinium crystals, (turbid phosphors) Question: Csi crystals (______ phosphor).
Gradolinium oxysulfide (_____ phosphor).Answer: Csi- , Gradolinium- turbid Question: 4 of CR:Answer: X-ray detection of CR is inefficient and this affects image quality and dose, Spatial resolution of CR is less than FS . CR IPs can easily be damaged. CR IPs must be transported to a separate image processor for image data extraction
Question: (flat panel DR) Selenium drum developed specifically for:
Answer: the chest Question: CCD indirect digital detector :Answer: x-ray, scintillator- , lens or fiber optic, CCD - electrical charge Question: CCD. Silicon chip is made of millions of pixels forming a matrix array of pixels. Light from the _____ falls upon each pixel to produce __________ (charges) in direct proportion to the amount of light falling upon them.Answer: scintillator, electron-hole pairs. Question: CCD. Bucket ?Answer: During readout, system electronics provide systematic of changes on each chip in a manner referred to as a “bucket brigade”. (the charge pattern from the readout of pixels is sent to the ADC for digitization) Question: CCD. What after the bucket brigade?Answer: The pattern from the readout of pixels (from the light of the scintillator falling on each pixel that produced electron-hole pairs...) is sent to the ADC for digitization. Then sent to computer for processing. Question: (indirect flat panel (TFT) detectors) ______ phosphors produce lateral spreading of light, which destroys the spatial resolution of an image.Answer: powdered. (this is why phosphor like Csi crystals are better) Question: TFT for?Answer: thin-film Question: Indirect flat TFT detectors: following the x-ray scintillator (x-ray detection medium) is what?Answer: an a-Si photodiode flat-panel Question: Indirect flat panel TFT detectors: a-Si layer is for what?Answer: to convert the light from the x-ray scintillator into electrical charges Question: flat panel TFT detectors: purpose of the capacitor?Answer: collect and store the charge produced in the a-Si photodiode array. Question: *** indirect detectors use a light sensitive photodiode to capture light from the ___________ phosphor such as _____ to produce electrical charges, the direct detectors use an ____ photoconductor to convert x-rays _____ into electrical charges.Answer: scintillator phosphor such as CsI, a-Se to convert x-rays directly Question: Indirect TFT: the purpose of the a-Si photodiode is ?Answer: To th elight from the x-ray detection scintillator into electrical charges. Question: TFT: the purpose of the capacitator is ?Answer: To collect and store the electrical charge in the a-Si photodiode array. Question: Direct TFT: the photoconductor is what substance?Answer: selenium (a-Se) Question: TFT: the photoconductor (a-Se) does what?Answer: detects x-ray photons from the and converts them directly into electrical charges. Question: Flat panel TFT: What is the or active matrix array-whats it consist of?Answer: consists of rows and columns that play a role in addressing and readout of the signal from each . Question: Flat panel TFT: each contains what 3 things?Answer: a TFT (switch), a capacitor, and a sensing area. Question: The sensing area (in each pixel of a TFT) will detect the light from the CsI scintillator in the indirect TFT detector, or in the case of a direct TFT, ______________.Answer: x-ray photons passing through the . (since there isnt a CsI scintillator?) Question: The sensing/storage element (of a pixel...) of an indirect TFT detector is the _________, and it is the ____________ in the direct TFT that uses the a-Se photoconductor.Answer: photodiode, capacitor. Question: The ______________ of the pixel receives the data from the layer above it that captures x-rays that are converted to light (indirect) or electrical charges (direct).Answer: sensing Question: Fill is what?Answer: defined as the ratio of sensing area of the pixel to the area of the itself Question: Fill factor is how?Answer: as a percentage. (Fill factor of 80% means that 20% of the pixel area is occupied by the electronics and 80% is sensing area) Question: Fill affects what 2 things?Answer: resolution and contrast resolution (detail and signal-to-noise) Question: Detectors with ____ fill factors (____ sensing areas) will provide better spatial and contrast resolution.Answer: high, Question: Indirect TFT detectors use a light sensitive ___________ to capture light from the scintillator phophor (such as CsI) to produce _________. Direct TFT detectors use an a-Se ___________ to convert the x-rays _________.Answer: photodiode, to produce electrical charges. Photoconductor, directly into electrical . Question: x-ray attenuation depends on what 3 ?Answer: atomic number (Z#), density, and thickness of material. Question: X-ray scintillators are what for flat panel TFTs?Answer: CsI and (gradolinium) Question: General principles/steps of indirect TFT?Answer: utilize a scintillator layer such as CsI to convert photons into light, these light photons strike the a-Si photodiode, which converts them to electrical . Question: operating principles/steps of direct TFT?Answer: photons fall upon the a-Se photoconductor layered on top of a matrix of a a-Si TFT array. As xrays strike the a-Se, electral charges are created and the electrical field causes them to move the TFT elements where they are collected and stored. Question: Before the flat panel detector can be used, it must be prepared. This is referred to as __________.Answer: . Question: What is exposure ?Answer: examines the of the image receptor to the radiation falling upon it. Question: EI does or does not represent an equivalent for dose entrance exposure?Answer: does Question: Raw digital data is first subject to pre-processing and presented as _______________ image.Answer: "for processing" . Question: After the image is presented as "for processing" image, it then undergoes digital image _____________, and the resultant image is labeled a _________________ image.Answer: post , "for presentation" image. Question: ____ processing improves contrast/appearance for the radiologist.Answer: Question: Image obtained initially from the detector is to as what?Answer: flat-field . Question: You base scaling the on what?Answer: the exposure on the detector. Question: Third step in image processing is ___________, where the adjusted or scaled raw data values are mapped to the "for presentation" values to display an optimum image.Answer: contrast . Question: "processing rules" are whatAnswer: avoid manipulating processing on a case-by-case - creates inconsistency in image appearance. Ensure modified processing parameters work on a variety of cases/people sizes. Question: the ability of the imaging system to resolve fine present in an object is calledAnswer: resolution Question: 3 tests to spatial resolution?Answer: bar test , sharp-edged object, narrow slit. Question: What is the transfer function? ***Answer: math function that measures the of the detector to transfer its spatial resolution characteristics to the image. Question: An MTF of ____ represents a perfect detector.Answer: Question: High frequencies contain _____, low frequencies contain ______.Answer: fine , contrast. Question: A system that has a higher spatial frequency at an MTF of .1 will show _____ spatial resolution than a system with below MTF of .1.Answer: Question: High MTF value at lower spatial frequencies means that the detector provides better _____.Answer: resolution Question: Dynamic of a digital detector is whatAnswer: the response of the detector to levels of radiation exosure Question: What is DQE?Answer: Detective quantum efficiency. "the of a detector to convert the x-radiation signal at its entrance window into useful image signal. Question: It is to have low or high SNR?Answer: Question: DQE can be as :Answer: DQE= SNR 2out / SNR Question: A digital detector would have a DQE of __.Answer: Question: As the spatial frequencies increase, the DQE ______Answer: decreases Question: Image lag is Answer: memory Question: Image lag to:Answer: the persistance of the image, that is, charge is still being produced after the beam from the tube has been turned off. |
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