Essential QA Part B

1. Essential QA Part B

2. QA Check 6Technical factors Use correct exposures for given body part. Caution* Depending on anatomy, Pediatric and Adult radiographs may use different S-value ranges.

3. QA Check 6Technical factors CR and DR technology display a much wider exposure latitude than conventional film screen technology, which in turn have greatly contributed to the decrease in repeat exposure rates. However the technologist must be aware that digital film density is no longer a marker for proper exposure. Manufactures of digital projectional radiographic systems have developed sensitivity values (Fuji’s S-value for example) and display these values with the final image. The sensitivity value helps determine the actual dose that was received to the phosphor plate. These values give us an “idea” of exposure and from there we can determine a range of values that are acceptable for each institution.Typically S-values under 100 are considered overexposed.

4. Determining exposure Film Screen technology Underexposed image appears light, washed out, under penetrated Repeat is typically determined by film darkening and image visualization Digital technology Underexposed image appears to have adequate density (blackening), however the image appears noisy or has excessive amounts of quantum mottle (photon starved). The following digital examples demonstrate adequate density and or contrast, however they each display high levels of quantum mottle or noise. All these studies should have been repeated, keeping in mind a good s-value range for that particular body part.

5. Underexposed, high levels of quantum noise

6. This lateral chest exhibits adequate density and grayscale, but the image was underexposed creating excessive noise. Perform a repeat

7. S- values this high are not acceptable

8. In the neonatal chest we often see higher acceptable s-values. S-values as high as 700-800 without excessive noise are common. This image however is too noisy and the s-value very high.

9. QA Check 7Collimation and Shuttering Proper collimation consistent with good radiation protection standards is required on all radiographs. Electronic shuttering should be used only where indicated.

10. QA Check 7Collimation and Shuttering Collimation and Shuttering are not synonyms! Collimation occurs at the x-ray tube prior to exposure. The technologist can reduce dose to the patient by exposing only the area of interest. Another well known benefit when collimating is the improvement in image quality due to the reduction of scatter reaching the imaging plate. Fewer scatter photons = cleaner, higher quality images

11. QA Check 7Collimation and Shuttering Collimation and Shuttering are not synonyms! Shuttering is a post acquisition option that may be applied at the digital QC workstation. The one and only reason for shuttering is to eliminate ambient light around the tightly collimated image. Studies have been performed that show glare from the surrounding tightly collimated image can reduce the visualization of small details in the radiograph, and distract from the Radiologists interpretation. Not all images require shuttering. Images that have been tightly collimated (pediatric chests and other small body parts) are eligible for shuttering. Adult chest x-rays that fill most of the imaging plate with anatomy and or primary beam, do not require shuttering.

12. Notice the obvious difference between the collimated edge and the edge of an electronic shutter.

13. This pediatric chest has good collimation, however the ambient light surrounding the image decreases conspicuity of fine detail.

14. This is the same image as the prior now demonstrating good collimation AND good shuttering. When shuttering, do not shutter off edges of collimation. Consistent with good quality assurance practice, continue to show the raw radiation edge. Shuttered edge Collimation/raw Radiation edge

15. QA Check 8Patient position indication Indicate patient position - upright, prone, decubitus, expiration, flexion, extension etc. Use Be-Be markers at the time of exposure or electronic markers post acquisition. If using electronic markers be sure the marker is visible. *Remember only lead markers are acceptable for indication of body side.

16. If patient position markers were not included at the time of exposure, electronic markers are an acceptable alternative. Indication of patient position in upright studies is a requirement.

17. Flexion and extension studies of the L-Spine may be exposed in the upright or recumbent position. In the absence of position markers, the Radiologist’s interpretation is limited.

18. QA Check 9Artifacts Clothing including snaps, zippers, bras, jewelry and body piercing are often missed when the technologist does not perform a through evaluation for all potential image artifacts. Additional artifacts may include bulky hair and braids, water bags and heating blankets, be sure to position all out of the field of view.

19. Ask the patient to remove all potential artifacts.

20. This is an interesting artifact that is often overlooked, can you spot it? Hair

21. Blanket and possible Water bag artifact

22. A repeat is necessary. This mystery artifact contributes to the total obliteration of the left lung.

23. QA Check 10Single view per plate Each digital image will take into account many factors to construct the visible image. Collimation, scatter, view and technique are a few of the properties necessary to create the final image. Another factor in constructing the digital image is the number of views taken on a single plate. Most phosphor plate technology (CR) is designed to look for a single view per plate. Another reason for acquiring one view per plate is the display properties that the Radiologist use at the diagnostic review workstation during interpretation. For comparison purposes, the preference is to display one view at a time on a single monitor. *Note Fingers and very small parts are the exception

24. Do not expose multiple views on one plate. Here we see the oblique view degraded due to scatter radiation. In addition, the lateral knee is over flexed at 90 degrees limiting evaluation of an effusion.

25. QA Check 11Window and Level Window and level refers to the contrast and brightness adjustment applied to the digital image after acquisition. Think of it as the contrast and brightness knob on your television, same result. Another adjustment can be made to the digital image that actually alters the histogram that constructs the grayscale of the original image. This adjustment is not the same as contrast and brightness and should not be changed. Performing contrast and brightness changes at the Fuji QC workstation, actually alters this histogram!

26. The following images represent destruction of the digital histogram due to post processing at the Fuji QC workstation.

27. The histogram of this image has been altered at the Fuji QC workstation. Note the complete washed out appearance of the image.

28. This is a X-table lateral of the abdomen that was altered at the Fuji QC w/s.The evaluation of free air is no longer possible.

29. Histogram alterations typically look like copied analog films with poor detail.

30. The Radiographic checklist Does my image pass high Quality Standards? • Is all the requested anatomy present on the Radiograph? • Is a LEAD marker present on the image? • Is the patient’s anatomy properly positioned? • To the extent possible, are all lines and tubes removed? • Is the exposure correct and within S-Value range for the exposed body part? • Is the collimation correct for the requested part? • Does the image require shuttering? If so, is it applied correctly? • Are all necessary patient position markers in place (upright, prone, etc.) • Is the image free of clothing and body artifacts (including hair and piercing). • One exposure per plate? • Was a grid used if necessary? • Was the correct processing parameter used? • Is the patient demographic information correct?

31. Congratulations! You have completed the Essential Image Quality for Projectional Imaging Course The Information Included in these Modules Represents the Basic Expectation of the Department for Imaging Quality.  Click here to proceed to Essentials post test