Adaptive Radiography: Tips and Tricks

Transcription

1 Adaptive Radiography: Tips and Tricks WCEC 20 th Student Educator Radiographer Conference Dennis Bowman, RT(R), CRT (R)(F) Community Hospital of the Monterey Peninsula (CHOMP) - Staff Radiographer Owner/Consultant - Digital Radiography Solutions, FluoroRadPro Speaker - MTMI Getting the part perfectly centered The proper centering criteria is the perfect place to start. Just make sure you don t end there unless it s appropriate. You need to always double check that you have all four sides on with the perfect amount of collimation or anatomy. Most of the positioning I do does not have a particular centering I just look at the top, bottom and both sides of the pre-built collimated lightfield. Final collimation may be needed. 1 finger collimation (1/2 ) is perfect. The Double Ping Pong Ball Experiment The following slides will prove how important it is to have a horizontal beam when looking for air/fluid levels or free air. All mention of the Bucky also means the ping pong balls (which really means the patient). The middle of the right ping pong ball was 8 cm from the IR. The middle of the left ping pong ball was 18 cm from the IR. There was 20 cc of water injected into the balls. 1

2 Bucky vertical and tube level with floor. Bucky vertical and tube 5 degrees caudad. Bucky vertical and tube 10 degrees caudad. Bucky vertical and tube 15 degrees caudad. Bucky vertical and tube 20 degrees caudad. Bucky vertical and tube 5 degrees cephalad. 2

3 Bucky vertical and tube 10 degrees cephalad. Bucky vertical and tube 15 degrees cephalad. Bucky vertical and tube 20 degrees cephalad. Bucky leaning back 5 degrees and tube 5 degrees caudad - they are parallel. Bucky leaning back 10 degrees and tube 10 degrees caudad - they are parallel. Bucky leaning back 15 degrees and tube 15 degrees caudad - they are parallel. 3

4 Bucky leaning back 20 degrees and tube 20 degrees caudad - they are parallel. Bucky is angled back 20 degrees and tube is level with the floor. This PA erect abdomen is the perfect example of free air that could be missed if taken with an angled beam. This is Billy and the closet he lived in. PA anterior ribs The posterior ribs are thicker and less curved. Even though on the PA view the anterior ribs are closest to the bucky, the posterior ribs will always show up better. 4

5 PA Upper Ribs It s good to use the full 17 length to get on the lower ribs if possible. The perfect PA. Sometimes air in the stomach or the colon can really help you out. RAO Upper Left Ribs Get spine to lateral border. Anterior ribs foreshortened, posterior ribs elongated. RAO - posterior ribs perfectly splayed out (even though they are further from the bucky). LAO Upper Ribs Remember that the sternum is now more medial than the spine. 5

6 Posterior ribs now foreshortened, anterior ribs are elongated (note anterior ribs have come across the spine). LAO - you can t get a better view of those anterior ribs than this. Sternum First get light field set-up by finding manubrium and xiphoid in AP position Then move the patient to the side, place your marker and center the IR to the light. RAO Sternum Shallow oblique of 20 degrees only. Center sternum to midline of bucky. Never believe the light field because it will always look incorrect. 6

7 Nicely seen RAO sternum How much does a scapula move? In this true AP the scapular body is parallel with the IR. True AP scapula. Patient PA and shoulder/scapula rolled forward (like a PA chest). Scapula is approximately oblique from PA. Scapula rolled forward approx degrees. Patient still PA but with arm completely brought across chest. Scapula is approximately degrees oblique. 7

8 Scapula approximately degree oblique. Patient s body only needs to be rotated degrees. Patient s body rotated degrees. PA Scapular Y Humerus vertical, body rotated 45 degrees. Exit at mid humerus side to side. You can either gauge the 45 degree angle across the chest or back. Perfect Scapular Y image. Note that humerus is directly superimposed over body of the scapula. 8

9 Perfect lateral scapula. Long PA Wrist Centering just proximal to styloid process. Show one-third to one-half of forearm. Perfect long PA wrist. Short PA Wrist Centered on styloid process. Classic 4 on 1 short wrist images. Although I almost never do it, this one time I shot a short wrist on a 15 year old because he could easily move the wrist around. 9

10 Because of the little density he saw on the lateral, he had me shoot a forearm. How much more anatomy can be seen on an abdomen when the SID is increased Classic distances are (were) 40 or 44 and 72. Patients are much larger now. Typical patient for abdomen 47 /51 using fluoro table bucky 53 /63 using movable table bucky 72 using upright bucky (also done PA) 10

11 In the Jan/Feb 2015 Peer Reviewed article of the ASRT Radiologic Technology Journal, it was proven that increasing SID will decrease patient dose Entrance surface dose, including backscatter was reduced by 39% and effective dose by 41% when the SID was increased from 100 cm (40 ) to 140 cm (55 ). In addition, the image quality is increased because the magnification and geometric unsharpness are reduced. The Ferlic Filter Typical hard to get, thick cm. shots like Swimmers and the x-table lateral hip are noticeably uglier, especially with CR. The Ferlic Filter is definitely needed. 11

12 Down while positioning the tube for a Swimmers or cross table lateral hip and then back up as the magnet holds it in place. In this position the filter is lifted and the round magnets hold it in place and for the exposure the filter is dropped down. Tip: The ASIS, the Universal Landmark Instead of using the symphysis pubis (SP), use the bottom of the ASIS. The bottom of the ASIS is located 3 above the upper edge of the SP. The bottom of the ASIS is also located 3 below the top of the crest. Tip: The ASIS, the Universal Landmark Top of Crest Radiographic Image Analysis by Kathy McQuillen Martensen Third Edition Bottom of ASIS Top of SP 12

13 Adaptive Radiography NOTES: Part B: Adaptive Skull Positioning Quinn B. Carroll, MEd, RT 2017 West Coast Educators Conference Orlando 1. Reversing positions, changing venues: For head and torso, the practical limit to CR angulation before distortion reaches problematic or unacceptable levels is about 45 degrees Any time a compensating angle would exceed 45 degrees, consider alternative general approaches (reverse, upright, different machine, etc Example: Modified Townes: Pt cannot flex chin, OML remains extended ab. 20 degrees Needed angle would be 20 compensating + 30 required for position = 50 degrees, exceeding limit Reversing position on the table does not solve problem Seat pt upright at CX board, reverse position, bend at waist to achieve angle, resting forehead on board Example: Estimate OML at 10 degrees flexed from horizontal: Contributes to angle Add degrees cephalic 2. Observe landmark lines (OML) carefully Always use 2 distinct points to define a line (i.e. exact outer canthus for OML) 3. Any PA or AP: Head over flexed or over extended: Simply angle the beam until the CR parallels the carefully observed OML 4. Three accurate lines for estimating flexion/extension: From OML: IOML = 7 degrees AML = 27 degrees Nasomeatal line (NML) = 17 degrees Pattern: All end in 7; Each goes up by Less accurate but still very useful: GML (glabellomeatal line): 10 degrees MML (mentomeatal line): 53 degrees 6. Caldwell upright: Use head extension rather than CR angle for fluid levels 15 degrees extension places NML perpendicular to IR, Forehead/chin ~ equidistant to IR 7. Visualize Projections from Tube s viewpoint Example: Caldwell related to Waters: Both use head extension = caudal angulation in PA, (cephalic angulation in AP) 8. Case Study #2: Caldwell for facial bones: Pt s chin slightly extended, uncomfortable to flex more You estimate the IOML = perpendicular to IR

14 What is the head position? What is the angled CR correction? With IOML perpendicular, head is extended 7 degrees CR correction: 8 degrees caudal 9. Case Study #3: Caldwell for facial bones: Pt s chin slightly hyper flexed due large nose, shaky so desirable to keep braced against table You estimate the horizontal = mid way between OML and GML What is the head position? What is the angled CR correction? Horizontal = mid way between OML and GML Head position 5 degrees flexed CR correction: 20 degrees caudal 10. Trauma Head Positioning: Pt supine, immobile Average situation: Head falls back Extension is us degrees = Rev Caldwell [No (or slight) angle for Caldwell] 11. Case Study #7: Reverse Caldwell #1: Pt supine, you estimate vertical = half way between IOML and AML What is the head position? What is the angled CR correction? Head extended 17 degrees (NML perp.) Close to 15 degrees, equiv. to angle No CR angle needed 12. Case Study #9: Reverse Caldwell #3: Pt supine, large shoulders, you estimate AML = vertical What is the head position? What is the angled CR correction? Head is hyper extended 27 degrees = 12 degrees overextension 12 degree caudal angle needed to cancel 13. The Special Case of the Waters Projection: The 37 degree angle in the atlas is the tabletop to OML angle formed when the head is extended 53 degrees At starting point of PA position, OML is NOT at 0, but at 90 degrees, and decreases as the chin is extended Over extension of the chin results in less than 37 degrees being measured, not more Actual amount of head extension is 53 degrees (MML roughly perpendicular)

15 14. Case Study #5: Waters for facial bones: Pt cannot fully raise chin You estimate that the nasomeatal line is horizontal What is the head position? What is the angled CR correction? Nasomeatal line is horizontal Head position: 17 degrees extended CR correction: 36 degrees caudal 15. Case Study #6: Waters for facial bones: Head is flexed 5 degrees Angle needed: = 58 degrees Exceeds limit of 45 degrees for distortion Position must be reversed 16. Reverse Waters Upright for facial bones: Place chair 8 10 away from chest board Extend head as possible, lean pt back at waist Label as AP 17. New positioning line for Waters: MML not very accurate OML must be measured with protractor / angligner [measurement also confusing] EZ line (Ear to Zygoma line) extends from TEA to laterally palpated bottom margin of body of zygoma With EZ line perpendicular to IR: Petrous ridges (at level of TEA) projected below maxillary sinuses 18. Reverse Waters Supine: Nearly all require cephalic angles Total of angle + head extension must = 53 degrees 19. Case Study #10: Reverse Waters #1: Pt supine, large shoulders, you estimate AML = vertical What is the head position? What is the angled CR correction? Head extended ab. 27 degrees, = cephalic angle for reverse position

16 Subtract = 26 degrees cephalic 20. Eliminating tilt on lateral head positions: KEY is the shoulders But the key to the shoulders is the elbow 21. Eliminating tilt: Chin lower than forehead: 1. Get elbow off table, support arm with hand 2. Then rotate shoulders as needed 3. Final touch: tuck chin 22. Eliminating tilt: Chin higher than forehead: 1. Use sponge: Wedge recommended Or 2. Angle CR to match interpupillary (IP) line *Relationship between CR and anatomy = more important than that between CR and IR 23. Zygomatic Arches: The Easy Way: Bilateral Reduce SID to 30 inches: Creates bilateral 15 degree angles Over angle CR upward 10⁰ beyond perpendicular to IOML Thanks for attending! Dennis & Quinn