All right, anode heel effect part two. So I'm just going to talk a little bit about how to use anode heel effect to your advantage and how to use this fat cap concept because it can help you with different thicknesses of anatomy. So we know already that the anode heel effect is the variance or difference in intensity between the anode and cathode sides of your beam.
And we know that the cathode side of your divergent ray is a higher intensity. Your anode heel effect can be increased or decreased by the angle of the anode, SID, field size, and other things, but it can be used to your advantage as a technologist and to your patient. So when you have a part that's not the same thickness from beginning to end, so we're not comparing like chest by itself and abdomen by itself, we're looking at abdomen as a whole. So say the upper portion of the abdomen, is that more dense than the sort of... pelvis side of the abdomen or the lower abdomen.
What side is thicker or what side might be more dense? And you put that part under the cathode side of the beam. And so that is what we use as far as your fat cap.
Fatter or thicker side would go under the cathode side of the beam. And so I have a couple examples here. Abdomen is, you know, sort of our easiest one. Abdomen thickness is the upper portion tends to be not as...
dense or thick as the lower portion. Normally the fat or the bony pelvis area at this section of the abdomen is thicker. So that part of the abdomen will go under the cathode end because it's more intense. Please ignore this divergent ray. It's going from tip-fib to chest, but you get what I'm saying.
If you're taking an abdomen x-ray, compare the upper part where the lungs are and you have a little bit of ribs versus the lower part where we have the pelvis and the bony areas this will be the more thicker part and so we'd put that under the cathode your APT spine if you're thinking up here at the cervical end versus down here by the abdomen which would be thicker so it tends to be thinner here at the upper portion by the cervical end the lower portion of the thoracic spine where it meets the lumbar spine is usually around the abdomen area. There's not a big variance in thickness in this patient, but there would be a difference in density here of the thicker portion because we're going to start to get into the abdomen area. If you have a bigger patient, their abdomen is going to be thicker here. It's going to give you more uniform density between upper and lower portions. So when there's a difference in thickness, the thicker part goes under the cathode.
If we're talking lateral T-spine, which part would be thicker or more dense when they're on their side? The shoulders, between the shoulders is going to be a greater thickness than down here at this end. So what is recommended is actually to do a right lateral. So you would take the patient's head, put it under the cathode side of your beam, and you do a right lateral so you can still see their back. And that would put the thicker portion under the cathode side.
You'd be able to penetrate this thicker area better than if you did the thicker portion under the anode side. So the shoulders of a lateral T would go under the cathode side. And I would suggest a right lateral.
This works great if they have really large shoulders to get this upper portion. It works really good. Femur is my last example.
And femur is different between hip and knee portions, right? So up at the knee tends to always be thicker and more dense. We have the femoral head and we have the acetabulum and a little bit of pelvis on versus down at this distal portion closer to the knee, it tends to be less dense. So whether you're doing the upper or the lower, this upper portion tends to be more dense. more dense in thickness, it tends to have more soft tissue or more fat involved than down here by the knee.
So you would put the hip or the proximal end under the cathode. So I hope that helps. This is not, again, a wild concept. The thicker part or the fat goes under the cat or the cathode. And so your anode heel is just saying the cathode side of your beam has more intensity.
So why not use that to your advantage? Put the thicker part of the patient under the cathode end. All right, I hope that was helpful.