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Factors Affecting Spatial Resolution

Eliminate motion Communication Shortest exposure time Synchronize exposure with patient motion •Reduce OID •Reduce focal spot size •Use detector with smallest detector element (DEL) •Reduce intensifying screen phosphor size and concentration (if using film system)•Increase SID

an increase in kVp

N/A

an increase in mAs

N/A

remove added filtration

N/A

-Which of these changes will improve the spatial resolution recorded in the radiographic image? 1 - Decrease FSS 2 - Decrease OID 3 - Increase SID

all

a decrease in SID

decrease in spatial resolution detail

Spatial resolution is also referred to as.

definition, sharpness, recordeddetail, or simply as detail

The spatial resolution of a radiographic system is measured with units of:

Line-pairs per millimeter Spatial resolution is measured in line-pairs per millimeter, sometimes written as "lp/mm". This makes sense because spatial resolution is the ability to see small part. If the x-ray system can visualize SEVERAL lp/mm, it would be said to have HIGH spatial resolution. If the system can only visualize a FEW lp/mm, it would be said to have LOW spatial resolution.

an increase in focal spot size

decrease in spatial resolution detail

for a group of technical factors which factors produce the best spatial resolution/ detail/ sharpness?

shortest time smallest focal spot size shortest oid longest sid

In a direct capture radiography system, a decreased detector element (DEL) size results in:

. Increased spatial resolution The DEL size refers to the physical measurement of the DEL, and smaller is better. As DEL size gets smaller, this improves the ability of the system to visualize smaller parts.

The values below were recorded on four different x-ray imaging systems. Which of these values represents the highest level of geometric sharpness?

20 lp/mm The x-ray system that can visualize the most lp/mm has the highest spatial resolution. As lp/mm increases, the size of the lines decreases, and the spatial resolution increases.

Which of the system specifications below will offer the highest spatial resolution?

2048 x 2048 matrix All x-ray imaging systems are designed with slightly different specifications by the manufacturer. Some of these specifications, like the matrix size, have an effect on the spatial resolution of the system. In this case, the system with the LARGEST matrix size will have the best spatial resolution. A large matrix has the MOST pixels and the SMALLEST pixels, both of which increase the system's ability to create clear images of small parts.

If all other exposure variables remain constant, which of these object-to-image distances (OID) will produce a radiograph with the LEAST amount of image blur?

4 inch For the lowest image blur, the object being images should be placed as close as possible to the image receptor. That's because a low OID will allow for only minimal beam divergence, decreased blurriness, and therefore increased spatial resolution.

If all other exposure variables remain constant, which of these object-to-image distances (OID) will produce a radiograph with the HIGHEST level of spatial resolution?

5 inches For maximum spatial resolution, the object being images should be placed as close as possible to the image receptor. That's because a low OID will allow for only minimal beam divergence, decreased blurriness, and therefore increased spatial resolution.

What is the relationship between matrix size and radiographic spatial resolution?

As matrix size increases, spatial resolution increases A large matrix has the MOST pixels and the SMALLEST pixels, both of which increase the system's ability to create clear images of small parts. So, as the matrix size increase the spatial resolution also increases.

Consider this scenario: During a cross-table lateral c-spine you decrease the SID from 72 inches to 60 inches. How will this modification affect the detail recorded in the image?

Decreased recorded detail Hopefully you know better than to use a 60 inch SID on a lateral spine. A higher SID is better for spatial resolution, so decreasing from 72 inches to 60 inches will DECREASE spatial resolution. Decreasing the SID causes more photon divergence, increased blur, and therefore decreased spatial resolution.

Consider this scenario: During a routine x-ray of an extremity, you change the exposure settings from the SMALL filament to the LARGE filament. How will this change affect the spatial resolution?

Decreased spatial resolution The filament size is one of the controlling factors of the focal spot size. A large focal spot size (FSS) allows for larger x-ray exposures, but it also decreases the spatial resolution. This is because the x-rays are not well aligned leaving the tube and the result is increased blur on the edges of objects. Increased blur is the same as decreased spatial resolution. The large filament should be used only when necessary for large (high mAs) exposures.

Increasing the focal spot size has what effect on spatial resolution?

Decreased spatial resolution A large focal spot size (FSS) allows for larger x-ray exposures, but it also decreases the spatial resolution. This is because the x-rays are not well aligned leaving the tube and the result is increased blur on the edges of objects. Increased blur is the same as decreased spatial resolution.

-Increasing the object-to-image distance (OID) from 1 inch to 2 inches will result in:

Decreased spatial resolution Increasing the OID decreases the spatial resolution. This is because the x-ray beam has more space to diverge and create blurry edges on the image. When possible, the OID should be kept as low as possible to maintain the highest spatial resolution.

As matrix size increases, pixel size:

Decreases There is an inverse relationship between matrix size and pixel size. Here's how it works: If we increase the matrix size of a radiograph, that increases the total number of pixels in the image. As a result, the pixels must get smaller in order to fit into the image. This is a good thing since smaller pixel can visualize smaller objects.

The geometry of the beam is the most important factor in establishing the level of resolution desired for detail and is determined by

Distances •Focal Spot size

An image with high spatial resolution would also be described as having:

High sharpness High spatial resolution is a good thing! An image with high spatial resolution has a high level of sharpness and the edges of objects are clearly visible without any blur.

Increasing the source-to-image distance (SID) results in decreased beam divergence and:

Increased spatial resolution Increasing the SID reduces the divergence of the x-ray beam as it approaches the image receptor. Decreased beam divergence is good because the x-rays will be more aligned and result in increased spatial resolution.

Digital receptor systems with a large DEL pitch will have:

Low spatial resolution The pitch refers to the space between DELs, and ideally this should be as small as possible. A large pitch means the DELs are more spread out and they will have a decreased ability to produce clear images of small parts. This results in decreased spatial resolution.

Aliasing

MoirePattern, Occurs when Nyquist Criterion is not met (incoming data are sampled less than twice per cycle)•Produces an inaccurate, fluctuating, low-frequency digital signal•Visual appearance of two images slightly out of alignment

a decrease in grid ratio

N/A

an increase in collimation

N/A

The space between pixels in a digital image is called the:

Pitch The distance between pixels is the "pitch". This measurement matters because a small pitch helps us to visualize smaller parts, which is the same as increasing spatial resolution. Matrix size refers to the total number of pixels in a digital image. Bit depth refers to the number of potential brightness levels the system can display. Exposure latitude is the range of exposures that will produce a good image at an acceptable dose.

The space between detector elements is called the:

Pitch The space between detector elements is called the pitch. Matrix size refers to the total number of pixels in a digital image. Bit depth refers to the number of potential brightness levels the system can display. Exposure latitude is the range of exposures that will produce a good image at an acceptable dose.

Which of these factors allow for the best visualization of small parts in a radiograph?

Pixel pitch = 0.1 mm Pixel pitch refers to the distance between pixels, just like DEL pitch refers to the distance between DELs. The smallest pixel pitch will have the smallest space between pixels and therefore provide the best visualization of small parts.

Scatter radiation does NOT affect:

Recorded spatial resolution Scatter radiation is bad (obviously), but scatter does NOT affect the RECORDED spatial resolution. The problem with scatter is that is covers the spatial resolution and makes the structural details in the image more difficult to see. So scatter does change the contrast in the image and the VISIBILITY of spatial resolution, but not the recorded spatial resolution. Scatter radiation is also the main source of occupational dose.

Which of these variables affect the spatial resolution recorded in the radiographic image?

SID A few variables affect spatial resolution, especially the SID, OID, FSS and patient motion. KVp and mAs have absolutely no effect on spatial resolution. In this question, remember that both SID and OID affect the alignment of x-ray photons while kVp and mAs do not.

The image below has low spatial resolution as a result of:

Small matrix size This image has a very small matrix size. This has several effects: 1) there are few total pixels, 2) the pixels are large, and 3) the spatial resolution of the image is poor. Radiographic imaging systems use a very large matrix to avoid problems like this.

The device pictured below is used to evaluate what aspect of an x-ray system?

Spatial resolution A spatial resolution device is easy to identify because it will always include a series of closely spaced lines. This device is also labeled with "LP/mm", which helps if you know that spatial resolution is measure din line pairs per mm (lp/mm).

Spatial resolution in digital radiography is defined as:

The structural sharpness recorded in the radiograph Spatial resolution is defined as the structural sharpness recorded in the radiograph. This is the same as the "detail" and the ability to clearly see small parts. You can also think of spatial resolution as the ability to clearly see the edges of objects in the radiograph. The other answer options do not relate to spatial resolution. Brightness levels refers to image contrast. Geometric distortion is the misrepresentation in size or shape. The total number photons reaching the receptor is the "receptor exposure".

Which of these anatomical parts can be an indicator of the spatial resolution recorded in the radiographic image?

Trabecular bone The quality of spatial resolution can be observed in the ability to see very small parts in the radiograph. This is why reviewing the sharpness of the very small trabecular bone is the perfect way to see the spatial resolution recorded in the image.

an increase in patient thickness

decrease in spatial resolution detail

an increase in screen speed(R/S)

decrease in spatial resolution detail

an increase inexposure time

decrease in spatial resolution detail

an increase of OID

decrease in spatial resolution detail

poor communication with the patient

decrease in spatial resolution detail

a decrease of OID

increase in spatial resolution detail

an increase in SID

increase in spatial resolution detail

immobilization devices

increase in spatial resolution detail

Which of these factors are expected to decrease spatial resolution in the radiographic image?

increased motion Spatial resolution is affected only by factors that change the alignment of x-rays photons as they pass by the edges of objects in the body. Increased motion definitely does affected spatial resolution because the edges of objects are blurred on the radiograph. KVP and mAs do NOT affect the alignment of x-ray photons, they do not change the sharpness of structural edges, and therefore they do NOT affect spatial resolution. Increased SID would actually INCREASE spatial resolution be reducing the divergence of the beam.

penumbra

is the imperfect, unsharp shadow surrounding the umbra, also called geometric unsharpnessor edge gradient.

The primary film/screen unit of resolution is

line pairs per millimeter (lp/mm) or cycles per mm.

Umbrais

the distinctly sharp area of a shadow or the region of complete shadow, also called geometric sharpness.

-Which of these equipment factors can influence spatial resolution in radiography? Choose multiple DEL size DEL pitch Matrix size Pixel size

· All of the above Each of these variables affects spatial resolution in a different way, but they definitely do affect spatial resolution. The ideal situation would be a small DEL size, small DEL pitch, small pixel size, and a larger matrix size.