CR Quality Control Summary

A consistent quality control program goes a long way toward maintaining a high standard of image quality within your radiology department.  The tests posted within this series are not all-inclusive for every CR system, but may provide as a good start for the beginning stages of any QC program.  Variations may occur if your department utilizes a hard-copy laser printer and/or measurement tools at the QC station (or to include the radiologists' work station).

As a general rule of thumb, most CR vendors recommend designating one person as the quality control technologist.  Other technologists may be trained in the event of an absence, but testing should be performed as consistently as possible to reduce variables.

Any QC test that does not meet specifications should first be repeated.  After a repeat test fails, a qualified service professional should be contacted to troubleshoot the problem.  Additionally, after any equipment repairs or replacement of parts, a new baseline should be established.

There may be additional troubleshooting to consider with equipment that might affect the QC testing results as well.  If you know of any aspect of the x-ray machine used to perform QC testing that is inconsistent, such as line voltage, mA station linearity problems, or timer malfunctions, these can also be researched prior to contacting the CR reader's service professional.  Ideally, the tests would be set up in the beginning to be performed on the most consistent equipment available.  Imaging departments may also consider annual contracts with service professionals if consistency may be an issue.

Your quality control manual should be kept in a safe place, but accessible in the event of a state or JCAHO inspection.  All results (even failing results) should be documented and maintained within the manual.  You may also consider keeping records of service calls and documents related to equipment repair on hand for future analysis.  Always watch for trends in test failures and use these trends to determine what service contracts and/or equipment repairs and replacement may best suit the needs of your department.

I hope you've found this series useful.  Here is a summary of all of the tests covered:


CR Quality Control #1 - Screen Cleaning
CR Quality Control #2 - Creating a Baseline Phantom Image
CR Quality Control #3 - Exposure Indicator Calibration
CR Quality Control #4 - Contrast Evaluation 
CR Quality Control #5 - Sharpness
CR Quality Control #6 - Shading Correction
CR Quality Control #7 - Laser Jitter
CR Quality Control #8 - Image Artifacts and Noise
CR Quality Control #9 - Exposure Linearity
CR Quality Control #10 - Residual Image Testing

CR Quality Control #10 – Residual Image Testing

This test evaluates the CR reader’s erasure function and should be performed semi-annually.  Each exposed image plate should be adequately erased during the processing cycle to prevent a residual image on the next image.

Procedure:

1. Erase your dedicated test IP
2. Place a lead apron on the floor of your x-ray room (use same room that baseline image was performed in)
3. Place test IP on lead apron
4. Place phantom on cassette (same orientation as baseline image)
5. Raise the x-ray tube to maximum height, center, and open collimation about 1" past edges of test IP
6. Expose the phantom at using twice the mAs value of the baseline image and process the image (or perform immediately following the system linearity test after the cassette has been erased on the exposure that was made at double the baseline).
7. Turn the phantom 180 degrees and place a radiopaque object in the center of the phantom
8. Expose at the normal baseline technique
9. Process the IP under “Contrast” menu selection

Results:

The processed image should appear normal compared to the baseline image, except that the phantom will be displayed upside down with the radiopaque object.  There should be no evidence of an additional phantom pattern.  If a residual image is present, re-test and call a service professional if the re-test does not eliminate the residual image.

Other posts in this series:


CR Quality Control #1 - Screen Cleaning
CR Quality Control #2 - Creating a Baseline Phantom Image
CR Quality Control #3 - Exposure Indicator Calibration
CR Quality Control #4 - Contrast Evaluation 
CR Quality Control #5 - Sharpness
CR Quality Control #6 - Shading Correction
CR Quality Control #7 - Laser Jitter
CR Quality Control #8 - Image Artifacts and Noise
CR Quality Control #9 - Exposure Linearity

Shape Distortion

One of the most fun courses I have taken and taught is exposure principles.  This course typically introduces students to different types of distortion that can occur on the radiograph.  Size distortion, otherwise known as simple distortion or magnification, occurs when OID is increased.  The other type of distortion, shape distortion, can be broken down into two main categories; foreshortening and elongation.

Foreshortening is when the radiographic image measures shorter in one dimension than the actual object being radiographed.  The only way this can happen is if the central ray and image receptor are perpendicular, and the object being radiographed is angled.  This is demonstrated in the image below (courtesy of students in the Radiography Program at OCTS/KCTCS) by comparing the top left, undistorted image, to the middle two which were placed on 45 degree-angled sponges.  This may also result in unequal magnification, where one side of the object may appear larger than the other due to differences in OID from one end of the angled part to the other.

Elongation is when the radiographic image appears longer than the object being radiographed.  There are several situations where this can happen.  If the central ray is perpendicular to the part, but the IR is angled, there will be more elongation with a greater increase in IR angle.  If the part is parallel to the IR, but the x-ray tube is angled, elongation can occur as in the bottom left image below (45 degree tube angle to the part).  Elongation can also occur when the x-ray tube is off-center to the part, even though the part may be parallel to the IR.  This is caused by the divergence of the beam, and is demonstrated by the two images on the right below.

*note - there would be no difference between an off-centered x-ray tube with collimation opened to the part compared to a tube angle from the same starting point (as long as the tube does not move).  Check this post out for more on that.

The image below is a similar experiment performed in one of my exposure principals labs.  We observe the following using a quarter, a 2" sponge, and a 45 degree angled sponge:

1. Perpendicular CR to the coin (parallel to the IR) with a 2" OID 
2. Coin parallel to IR on 2" sponge, but 45 degree tube angle
3. Tube returned to perpendicular to IR, but quarter is angled 45 degrees
4. CR angled 45 degrees (perpendicular to angled quarter)
5. CR angled half the part angle (demonstrating an isometric principle)

You'll notice very slight elongation in image 2 compared to the first.  Image 3 is quite foreshortened, and image 4 has the most elongation.  Image 5 is very useful for trauma views, and is illustrated with exams like the axial calcaneous and AP sacrum/coccyx.  The tube is angled half of the part's angle to the IR.  This reduces the effects of elongation as much as possible, so our exposure 5 measures the same as exposure 1.

CR Quality Control #9 - Exposure Linearity

This test should be done semi-annually and tests for the CR system's ability to properly rescale images that are over or under exposed.  It also measures accuracy of the exposure indicator and its ability to increase/decrease in relationship to the exposure value.

Procedure:

1. Erase your dedicated test IP
2. Place a lead apron on the floor of your x-ray room (use same room that baseline image was performed in)
3. Place test IP on lead apron
4. Place phantom on cassette (same orientation as baseline image)
5. Raise the x-ray tube to maximum height, center, and open collimation about 1" past edges of test IP
6. For all following exposures, annotate the technical factors used, exposure indicator, date, and which reader the image was processed on.

Exposure 1 - should be set with the same kVp as the baseline technique, but half the mAs.  .

Exposure 2 - should be the same technical factors as the baseline exposure.

Exposure 3 - should be performed with the same kVp as the baseline technique, but double the mAs value.

Results:

The brightness of each of the three images should be the same.  If there is variation, you may have a problem with the automatic rescaling function (click here to read more about automatic rescaling).

Exposure 1 should display a change in baseline exposure indicator to represent 1/2 the exposure +/- 20% (S# = baseline x 2, EI = baseline - 300, LgM = baseline - 0.3).  Exposure 2 should be within +/- 20% of the baseline reading.  Exposure 3 should display a change in baseline exposure indicator to represent a double in exposure value +/- 20% (S# = baseline x 0.5, EI = baseline + 300, LgM = baseline + 0.3).

Use the following formula to calculate percentage of change (click here for detailed instructions how to calculate percentage of increase or decrease):

new exposure indicator - baseline exposure indicator  x 100
                  baseline exposure indicator 

If variance is outside the +/- 20%, service personnel should be contacted.

Other posts in this series:

CR Quality Control #1 - Screen Cleaning
CR Quality Control #2 - Creating a Baseline Phantom Image
CR Quality Control #3 - Exposure Indicator Calibration
CR Quality Control #4 - Contrast Evaluation 
CR Quality Control #5 - Sharpness
CR Quality Control #6 - Shading Correction
CR Quality Control #7 - Laser Jitter
CR Quality Control #8 - Image Artifacts and Noise
CR Quality Control #9 - Exposure Linearity
CR Quality Control #10 - Residual Image Testing

Radiographic Alternative for Opening Joint Spaces

We all know the basics of opening joint spaces on our radiographs.  Keep the joint space opening perpendicular to the image receptor while aligning the central ray directly to the joint.  No problem... x-ray 101 right?  But what about those joint spaces like wrists and ankles?  You know, the ones where some of the radiologists say "you should have gotten more of the tibia (or forearm)!"  Sometimes it's good to include a little extra - especially if your radiologists prefer it when there is obvious deformity.

The problem lies within x-ray beam geometry.  I was going to make a video to demonstrate a basic principle in beam geometry, but Peter Gleeson did an exceptional job on his YouTube channel... watch his short video before we move on to some possible solutions.

Now that we know a tube angle does not change the distortion of an object because the x-ray source does not change position, we can evaluate our options... below, we have a traditional positioning setup for an AP ankle.

Sometimes we need a bit more of the distal tib-fib.  One proposed solution I have seen is to simply move the joint to the bottom of the image receptor, while placing the central ray a few inches above the joint space.  This accomplishes our goal of including more of the distal tibia, but can also close the ankle joint because it no longer lies directly in the central ray.  The beam is divergent at the point of intersection with the joint.

I have seen the following method used in another state that does not have very strict guidelines on radiation protection.  The tech would center to the joint space, but open the collimated field beyond the edge of the image receptor.  I do NOT recommend this for ALARA purposes, but I thought I would throw this example in there because I have seen it before.

I propose we can take the best of both worlds with the following solution.  Start out with the central ray over the joint space as in the previous example.  Without moving the x-ray tube (longitudinal, transverse, or vertical) from its current location, angle it cephalic so the crosshair is a few inches proximal to the joint space.  Collimate vertically so the field size does not go beyond the image receptor.

If you watched the video, you understand that the actual source of photons does not change with the tube angle.  There is still a perpendicular path of x-ray photons opening the joint space, while we include more of the proximal tib-fib.  The only disadvantage is there will be some elongation of the tibia near the periphery of the field of view.  But also take note that the same amount of elongation would occur in the prior method due to the same beam divergence.

Don't believe me?  Take any 3-dimensional object and place it directly under your perpendicular central ray.  Open the collimation and angle the tube in either direction.  You will notice (just as in the video) that the object's shadow does not move.  As long as you do NOT move the tube from its current location prior to tube angulation, the beam divergence will be exactly the same with the tube angle as if you simply opened the collimation.

I should mention that the BEST way to avoid this whole scenario would be to have the physician order a tib-fib (or correct corresponding body part).  But since we as technologists cannot order the exams, sometimes we have to make the best out of imperfect situations.

UGI Image Evaluation

One of the things I used to do multiple times per day as a radiologic technologist was upper GI's.  Though they're still being done quite a lot these days, I often forget how much effort we spent in x-ray school to learn how to properly tell them apart for hanging protocols.  We can distinguish our views by evaluating three things:

1. Location of barium within the stomach
2. Location of air within stomach
3. The spatial relationship between the stomach and spine

If you take the first image below, it's easy to look at the radiograph and think it was performed supine, when in fact, it was exposed with the patient prone.  The original x-ray may have been flipped horizontally upon first glance, but we are required to hang images in the anatomical position so it has been flipped.  The fundus of the stomach is full of air, while the body contains barium.  It is also superimposed over a non-rotated spine.  This tells me the patient was prone.

On a double-contrast study, we need to remember how the anatomy lies in relationship to other structures to tell the difference.  The fundus is superior to the body and also rests more posterior.  I can tell it is prone because the air will rise to the most posterior anatomy when prone.  I know this is not an upright exposure because while it would also demonstrate the barium in the body of the stomach, there would be more of a horizontal line separating the air/fluid level.

The lateral stomach view below demonstrates how the fundus is posterior to the body.  I know different hospitals can have different hanging protocols for lateral views.  So if I'm going to evaluate the image below to tell which lateral was performed, I could also reference the picture above knowing that the fundus lies to the patient's left side while the body and pylorus are more midline.  If we remember that the air will rise while barium settles, it should be easy to differentiate between a right and left lateral.  Since the barium is exiting the body and collecting in the pylorus and duodenum, we know that the patient's right side is down and a right lateral was performed.

Now, lets talk about oblique views.  Still referencing the first image, we can tell that if an RPO is performed, the stomach should superimpose the spine, which is typically undesirable for UGI studies.  The same would hold true for the opposite LAO.  We almost always perform RAO or LPO views of the stomach to free the pylorus, body and duodenum from superimposition of the spine.  That being said, look at the next image.  We can tell it is LPO because the stomach is free of the spine, and the body is full of air.  This is actually one of the radiologist's spot views.  After the stomach drains some of the contrast, the barium coats and we can rotate the patient to allow air to accumulate at the juncton.  Unfortunately, we cannot visualize the fundus, which is most likely full of barium, which would support our claim that this is an LPO.

*Tip: although the textbooks say "rotate 45 degrees," we should be mindful as technologists of the reasons for the rotation.  In this case, the radiologist needs to visualize gastric emptying function in profile while not being superimposed by the spine.  Some times we need to rotate more or less depending on patient body habitus, so keep an eye on the fluoro monitor when assisting the patient while rotating.  If you rotate 45 degrees, it may not be enough to adequately allow for an optimum view.  When contrast is involved, we need to be efficient, so we don't want to stand there waiting for the radiologist to tell us to turn the patient more while we're missing a good opportunity to image the stomach emptying.

Compared to the image above, the next set of images differs in that the barium is in the body, while air is in the fundus.  This tells us the fundus is superior to the body, but we also know it's an oblique due to several give-aways.  The fundus and body are free of superimposition of the spine, and you can also notice rotation of the spine itself.  For these reasons, we know these are RAO views.  They were taken in the position of the bottom left image below (where the fundus is closer to the x-ray tube/superior to the rest of the stomach).  The images were then flipped horizontally to represent anatomical position like in the bottom right image.

Evaluating UGI images can be somewhat confusing at first, but once you get it, it's like riding a bike.  If you can visualize how the stomach lies within the abdominal cavity, it's not so difficult.  Acquiring that knowledge early on in your studies will make a huge difference later when you're in the middle of a procedure.

*if you like the virtual images I posted, check out the interactive anatomy site, https://www.biodigitalhuman.com/.  There is an interactive anatomy skeleton with all body tissues which gives you the opportunity to isolate tissues of interest, rotate, zoom, and a few other helpful tools.

Radiographic Sitzmarker Study

Unless you work in a hospital that routinely treats pediatrics or you have been around the world of radiography for a while, you may not have seen a Sitzmarker test.  This exam is done for patients who have experienced chronic constipation, and may be used to support a number of gastrointestinal disorders.  

Procedure:  A capsule is swallowed containing several metal rings encased in plastic.  Once the capsule dissolves, the rings disperse and can be followed through the GI tract.

I have seen varying routines depending upon radiologists' preference at different imaging departments.  The patient could return every day (approximately the same time of day) for a follow-up KUB, and I have seen them spaced out as far as 5 days.  The dictation should note the difference in location of the rings, as well as the amount of time for motility to allow the rings to pass.

The normal GI tract should evacuate the rings within 2-3 days.  Other disease processes could make the rings take more or less time, but most frequent findings are with constipation where it delays passage for more than 5 days.

Radiography School Checklist

Happy Easter!  Here's a free download (updated) for anyone who is thinking about going to radiography school.  Make sure to research your local job market in addition to completing this checklist.

Click on the image to download

CR Quality Control #8 - Image Artifacts and Noise

Perform this test monthly along with other monthly QC or as needed.  Your radiologists will usually inform you they are seeing artifacts on images before technologists notice them due to the high resolution of their screens and necessity to magnify images.  No additional exposures are necessary, and you may use the test images from any of the other tests.  This can test for the presence of noise or artifacts originating from the image plate, CR reader, or the hardcopy laser printer.  Example digital images from an actual exam:

As you can see, the artifacts are quite visible once magnified.  Just imagine how much more visible these artifacts would be on a high resolution monitor in front of the radiologist!

Procedure:

1. Erase your dedicated test IP
2. Place a lead apron on the floor of your x-ray room (use same room that baseline image was performed in)
3. Place test IP on lead apron
4. Place phantom on cassette (same orientation as baseline image)
5. Raise the x-ray tube to maximum height, center, and open collimation about 1" past edges of test IP
6. Use the same technical factors that produced the baseline image (check monthly log for exposure factors) and make an exposure
7. Annotate exposure indicator number and which CR reader was used and ensure that it is within specifications.

Things to look for:

• Grainy appearance of image - ensure that the Exposure Indicator is within specifications - could indicate mottle produced by improper exposure factors or incorrect physical setup
• Inspect the image plate for debris or scratches that can produce artifacts with reduced density on your radiographs
• A longitudinal white line across the entire image indicates dust on the light guide.  Have a service rep clean the reader
• Any artifacts on a hard-copy film that may be caused by the printer (present on film, but not on digital image)
• Variations in brightness across the digital image.  This could be specific to the monitor you are viewing and can be cross-referenced with another viewing station to isolate the problem

Other posts in this series:

CR Quality Control #1 - Screen Cleaning
CR Quality Control #2 - Creating a Baseline Phantom Image
CR Quality Control #3 - Exposure Indicator Calibration
CR Quality Control #4 - Contrast Evaluation 
CR Quality Control #5 - Sharpness
CR Quality Control #6 - Shading Correction
CR Quality Control #7 - Laser Jitter
CR Quality Control #8 - Image Artifacts and Noise
CR Quality Control #9 - Exposure Linearity
CR Quality Control #10 - Residual Image Testing

CR Quality Control #7 - Laser Jitter

This test will determine whether the mechanical motion of the image plate, laser, and optics are consistent in the transport system of the CR reader.  It should be performed monthly, or after any service to the CR reader.

Procedure:

1. Erase your dedicated test IP
2. Place a lead apron on the floor of your x-ray room (use same room that baseline image was performed in)
3. Place test IP on lead apron
4. Place phantom on cassette (same orientation as baseline image)
5. Raise the x-ray tube to maximum height, center, and open collimation about 1" past edges of test IP
6. Use the same technical factors that produced the baseline image (check monthly log for exposure factors) and make an exposure
7. Annotate exposure indicator number and which CR reader was used
8. Print a hard-copy image on the laser printer
9. Inspect the edges of the "T" in the middle of the phantom for jagged edges

According to FUJI's FCR QA 1 Shot Phantom manual, a certain degree of jagged edges is expected, but under 2X magnification on the QC or reading stations, they should not be visible to the human eye.  Compare the new image to the baseline phantom image.

If the jagged edges appear at the QC station and the laser film, the reader should be serviced.  However, if the jagged edges only appear on the hard copy, but not the QC station, there may be a problem with the laser printer.  Call service and record results on the monthly log.

Other posts in this series:

CR Quality Control #1 - Screen Cleaning
CR Quality Control #2 - Creating a Baseline Phantom Image
CR Quality Control #3 - Exposure Indicator Calibration
CR Quality Control #4 - Contrast Evaluation 
CR Quality Control #5 - Sharpness
CR Quality Control #6 - Shading Correction
CR Quality Control #7 - Laser Jitter
CR Quality Control #8 - Image Artifacts and Noise
CR Quality Control #9 - Exposure Linearity
CR Quality Control #10 - Residual Image Testing

CR Quality Control #6 - Shading Correction

This test checks to see if the CR scanning laser has uniform intensity across the entire image plate.  It should be performed monthly, or after service to the CR reader's light guide and/or optics.  While this test can be visibly inspected on digital monitors, it can only be quantitatively performed using hard-copy dry laser film with a densitometer.

Procedure:

1. Erase your dedicated test IP
2. Place a lead apron on the floor of your x-ray room (use same room that baseline image was performed in)
3. Place test IP on lead apron
4. Place phantom on cassette (same orientation as baseline image)
5. Raise the x-ray tube to maximum height, center, and open collimation about 1" past edges of test IP
6. Use the same technical factors that produced the baseline image (check monthly log for exposure factors) and make an exposure
7. Annotate exposure indicator number and which CR reader was used
8. Print a hard-copy of the phantom image
9. Measure the optical density of the middle measuring point and document
10. Measure the optical density of the outer-lying points and document

 

 

The acceptable variance in optical density of the outer two measuring points (compared to the center) is +/- 10%.  If measurements exceed this variance, repeat the test.  Call a service engineer if still outside acceptable standards.

Other posts in this series:

CR Quality Control #1 - Screen Cleaning
CR Quality Control #2 - Creating a Baseline Phantom Image
CR Quality Control #3 - Exposure Indicator Calibration
CR Quality Control #4 - Contrast Evaluation 
CR Quality Control #5 - Sharpness
CR Quality Control #6 - Shading Correction
CR Quality Control #7 - Laser Jitter
CR Quality Control #8 - Image Artifacts and Noise
CR Quality Control #9 - Exposure Linearity
CR Quality Control #10 - Residual Image Testing

Improved Portable Chest X-Rays with Grids

I know I have posted about this topics before, but I would like to stay on this soap box for a while because I know that education still needs to occur regarding dose reduction techniques using CR and DR equipment.  Over the past several years since I began writing here, a lot of improvements have been made in the materials used and sensitivity of our digital radiography equipment, which reduces radiation dose significantly.  For some reason, either technology has progressed far faster than the continuing education of our peers, or technologists are resisting the pace of change occurring with imaging technology, and grids are not being used as they should.

In 2008, I had the pleasure of attending a workshop on digital radiography with lecturers Barry Burns, James Barba, and Andrew Woodward at the University of North Carolina.  After putting to practice the principles taught there, everything has held true over the last 5 years.  I'm going to show you two recent x-rays of the same patient which support the information presented.  The first was done without a grid and the second with a grid.  Keep in mind that the patient was just over 100 lbs, so very small in relationship to the average patient size.

85 kVp 5 mAs, non-grid, optimum exposure indicator

120 kVp 3.2 mAs, 8:1 grid, optimum exposure indicator

Both of these images were taken using some very aged FUJI CR image plates (see image plate chipping damage on top of the images - I hear they're being replaced).  They were taken by different technologists within the same week.  The non-grid film was taken in an ICU bed prior to portacath insertion, while the gridded image was obviously taken after.

Advantages:

• Higher quality beam = more uniformly penetrating.  You can not only see thoracic spine through the mediastinum, but there is also better visualization of the central line, chest tube and NG tube.  It is difficult to see below the diaphragm or even through the mediastinum at lower kVp without a grid.
• Higher kVp and lower mAs = lower patient dose.  With higher kVp, the entrance skin exposure is lower because there is more energy behind the photons pushing them through the patient anatomy.  The lower mAs value speaks for itself as mAs is directly proportional to intensity.

Disadvantages (trying hard to come up with any):

• Some technologists struggle with grid cutoff on portable chest exams.  Strategies for reducing cutoff include perpendicular beam, using lengthwise orientation when possible, or utilizing a short-dimension grid.  Sliding the patient up in the bed prior to sitting the head of the bed up is essential (read "Lordotic Much?" at the end of this post).  In other words, there is less positioning latitude.

In my opinion, there is a clear choice.  When we can prioritize patient dose while improving image quality, why would anyone want to do otherwise?  Of course, I'm here to learn as well as to publish my opinion, so I welcome any comments, suggestions, criticism, etc.

Other related posts:

Lordotic Much?

To Grid or Not to Grid

CR Quality Control #5 - Sharpness

This test ensures the display and image processing systems are operating within normal specifications.  This test should be performed monthly or after servicing of the CR reader.

Procedure:

1. Erase your dedicated test IP
2. Place a lead apron on the floor of your x-ray room (use same room that baseline image was performed in)
3. Place test IP on lead apron
4. Place phantom on cassette (same orientation as baseline image)
5. Raise the x-ray tube to maximum height, center, and open collimation about 1" past edges of test IP
6. Use the same technical factors that produced the baseline image (check monthly log for exposure factors) and make an exposure
7. Annotate exposure indicator number and which CR reader was used
8. Compare the line pairs/mm on the new image to that of the baseline phantom image

According to the user manual for this phantom, the copper filter within this phantom produces a large amount of scatter which will reduce the actual visibility of detail in our test image, so it shouldn't be used to determine system resolution.  My hospital will need a stand-alone line-pair resolution test pattern for that determination, so check your manual to see if the same is true of your phantom.

When at all possible, use the magnification tool for each workstation to compare the new image to the baseline.  Record any variances, and if a moire pattern is observed, you may need to repeat your phantom exposure prior to recording your observations.

Note: the image on my blog is dramatically reduced in resolution compared to that visible by the radiologist's monitor in the reading room.

Other posts in this series:

CR Quality Control #1 - Screen Cleaning
CR Quality Control #2 - Creating a Baseline Phantom Image
CR Quality Control #3 - Exposure Indicator Calibration
CR Quality Control #4 - Contrast Evaluation 
CR Quality Control #5 - Sharpness
CR Quality Control #6 - Shading Correction
CR Quality Control #7 - Laser Jitter
CR Quality Control #8 - Image Artifacts and Noise
CR Quality Control #9 - Exposure Linearity
CR Quality Control #10 - Residual Image Testing

Pinterest... Doing it Right

With the rise of new social media that seems to occur almost every day, I find it difficult to find the time stay current on all the rules and regulations that are set for each.  I recently began integrating Pinterest with my other social media because of how easy it allows me to share the image-based content we are all interested in.  After using it for a while though, I have noticed some definite do's and don'ts when pinning images to one of my boards.  

The main issue I see happening is failure to credit the original website/author/photographer.  If 10,000 pinners "repin" something of mine, and I'm linked to the original site where I found the image, all it will do is increase traffic to that site which should make the owner very happy.  However, if I pin or repin an image from a location other the owner's site, then the original author will not get credit whenever other people view and/or repin.  

This has other repercussions as well.  If I (the image seeker) like the image and there is more relevant content on the original site I may be interest in, I may never see it because I don't have the appropriate source linked to the image I like. It will also eventually frustrate some of my board followers.  Even though they may love the images I'm placing on my boards, they will have to click through a few times searching for the original image.  For instance, I repin something from another board I saw, and that person repinned it from someone who didn't site the original source as well, but pinned it from someone who did.  Going through 3 or 4 extra click-throughs to find the original source doesn't sound like a lot of time to waste, but your follower may choose to simply unfollow you and follow the person who sited the source image... you lose followers and may even see yourself getting reported as Pinterest users become more savvy.

Another important guideline to follow while pinning to your own board is don’t post directly from other image databases.  Google images for example, like Pinterest, has created a database of images that came from an outside source.  While browsing through Google images, take the time to click through to the original site where google extracted the image before pinning it. It may take one or two extra clicks to follow the image to it's origins, but your followers will appreciate it and you can rest easy at night knowing you are pinning ethically.

I haven't heard of any copyright issues with this, although I think there may be some potential.  Social media like Pinterest improves convenience for the user, but because it's so new, the legal system hasn't really caught up to some of the possibilities that can occur with it.  Responsible sites have suggestions on etiquette that should steer users clear of potential copyright or plagiarism issues.  For those and other useful guidelines, you should be able to find them rather easily for each respective social media site.  Click here to see Pinterest's guide to etiquette.

As suggested by the Pinterest etiquette guide, if you know someone is pinning improperly without siting the original source, feel free to leave a comment letting them know.  You don’t need to be rude, but you could say something like “I wish I knew where the original site was for this image.”

Would you like to follow me on Pinterest?  CLICK HERE :-)

CR Quality Control #4 – Contrast Evaluation

Perform this test to see if the CR’s ability to visualize scale of contrast is comparable to the initial baseline image.  You can evaluate the contrast for hard copy film, the CR QC station, and the radiologist’s reading station. 

Procedure:

1. Erase your dedicated test IP
2. Place a lead apron on the floor of your x-ray room (use same room that baseline image was performed in)
3. Place test IP on lead apron
4. Place phantom on cassette (same orientation as baseline image)
5. Raise the x-ray tube to maximum height, center, and open collimation about 1" past edges of test IP
6. Use the same technical factors that produced the baseline image (check monthly log for exposure factors) and make an exposure
7. Annotate exposure indicator number and which CR reader was used
8. Visually compare the contrast areas on the new exposure of the phantom with the contrast areas on the baseline image in your archive (*note – the brightness and contrast settings on your viewing monitors should be the same as when the baseline image was evaluated)
   

Evaluation:

The contrast area on the left (for my phantom) consists of two circles of Pb (lead) equivalent material.  The outer circle is 0.15 mm Pb, while the inner is 0.5 mm Pb.  

The contrast area on the right consists of an empty hole, while the inner circle is made of 0.7 mm Cu (copper).

A simple visual comparison is enough to determine a pass/fail result.  Keep a few things in mind when looking at the images:

The monitors will degrade over time, which can provide some display inconsistency.  It is advised to observe both the QC monitor and the radiologist’s monitor for variation.  If only one of the monitor’s display appears to be sub-par, while the other appears optimum, consider replacing the sub-par monitor.  However, if both monitors appear sub-par, it is more likely due to a reduced contrast performance of the reader, and a service engineer should be notified.

If you are comparing using hard-copy film, you can use a densitometer to get a precise density difference measurement from each contrast area, comparing the outer circles to the inner.

Other posts in this series:

CR Quality Control #1 - Screen Cleaning
CR Quality Control #2 - Creating a Baseline Phantom Image
CR Quality Control #3 - Exposure Indicator Calibration
CR Quality Control #4 - Contrast Evaluation 
CR Quality Control #5 - Sharpness
CR Quality Control #6 - Shading Correction
CR Quality Control #7 - Laser Jitter
CR Quality Control #8 - Image Artifacts and Noise
CR Quality Control #9 - Exposure Linearity
CR Quality Control #10 - Residual Image Testing