Room Setup:
The easiest way to perform this view is to align your central ray with your image receptor prior to aligning the patient. Make sure that you align it high enough so you can pump up the stretcher to the desired central ray instead of having to adjust the tube and bucky. Set your 40 inch SID to the upright receptor and place your marker in one of the inferior corners of your light field after you collimate. As we know, the more we collimate, the greater our radiographic detail will be. So you can collimate from side to side at least two inches on a 10 x 12 cassette placed lengthwise if the patient can stand or sit upright in a stretcher (or make your light field about four finger-widths across), and crosswise if the patient will remain supine for the exam. The humeral head is only about the size of a racquet ball, so this should leave plenty of room as long as you align your patient properly.
When setting technical factors, a breathing technique is highly desired. I like to consider what type of technique to utilize for a lateral t-spine on my patient after viewing body habitus, and set that exact technique for male patients, and possibly one step lower in mAs for hyposthenic patients (your 84 year old grandmother who weighs 99 lbs). Your kVp should remain in the 70 – 75 range and of course, small focal spot should be selected to accommodate the low mA setting required for your breathing technique.
Performing the exam:
When bringing the patient in the room, make sure that they are bending at the waist by sliding them up if needed. You will also need the patient’s injured side close to the stretcher edge. Sit them upright (if possible) and proceed to aligning them.
I always like to align the patient like I were doing a lateral chest in the stretcher. Since you already aligned the bucky with the central ray, and you have collimated, leave the patient’s arms by their sides and align your light field so that the top of the light field enters just above the good side (or side up). For example, if you are performing a left humerus, leave the right arm down while aligning, and place the top of your light field just on top of the right humeral head before raising it.
Make some fine adjustments if needed by raising or lowering the stretcher or moving the stretcher foreword or backward. You may wish to “cock the box,” as I call it, or rotate the collimator housing to align with the plane of the affected humerus. Once you are all lined up, consider your technical factors and you’re ready to expose… almost. Don’t forget to raise the unaffected arm before you do. The patient should breathe normally (or sometimes instructed to breathe with slow deep breaths), and you should make a 3-4 second exposure during inspiration (because it takes longer than expiration).
Keep in mind that if there is a dislocation, the majority of humeral dislocations occur anteriorly. Just make sure to check your alignment on the side of interest before exposing and remove any artifacts that normally get in the way such as a bra or those pesky metal splint clips.
Given the high radiation dose this technique should NEVER be used
ReplyDeleteWhy do you think this would be such a high dose? With CR/DR you could even raise the kVp to 80 or more, and the mAs required would be far less than that of a lateral T-spine. Do you have any other methods that will allow for visualization of the proximal humerus if there is a fracture?
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