 Pick up Composition Notebook  Pick up Article on Diagnostic Imaging  Select One Diagnostic Image  Please remember which envelope!

1. Get out Composition Notebook 2. Pick up the article:  Medical Imaging: Getting inside your head (and other parts). 3. Read and interesting section of the article 4. What did you learn?  Don’t forget? ▪ Title for journal entry ▪ Date ▪ Complete sentences!

 Look at your Diagnostic Image  List all the things that you can see?  What could you learn from it?

 Fundamental to understanding  Helps to tell location of disease  Helps to tell what they may be

 Plain x-rays  CT scan  MRI  Nuclear imaging/PET  Ultrasound  Mammography  Angiography  Fluoroscopy

 X-rays: a form of electromagnetic energy  Travel at the speed of light  Electromagnetic spectrum X-rays  Gamma RaysX-rays  Visible lightInfrared light  MicrowavesRadar  Radio waves

 X-rays can:  Pass all the way through the body  Be deflected or scattered  Be absorbed Where on this image have x-rays passed through the body to the greatest degree?

 Depends on the energy of the x-ray and the atomic number of the tissue  Higher energy x-ray - more likely to pass through  Higher atomic number - more likely to absorb the x-ray

 X-rays that pass through the body to the film render the film dark (black)  X-rays that are totally blocked do not reach the film and render the film light (white)  Air = low atomic # = x-rays get through = image is dark  Metal = high atomic # = x-rays blocked = image is light (white)

 Air  Fat  Soft tissue/fluid  Mineral/Bone  Metal

Absorbed Passed through

 Air  Fat  Soft tissue/fluid  Mineral/Bone  Metal Name these radiographic densities.

 Any structure, normal or pathologic, should be analyzed for:  Size  Shape and contour  Position  Density (You must know the 5 basic densities)

 X-rays pass through the body to varying degrees  Higher atomic number structures block x- rays better, example bone.  Lower atomic number structures allow x- rays to pass through, example: air in the lungs. Question: If x-rays were blocked to the same degree by all body structures, could we see the internal parts of the body?

 Air  Fat  Soft tissue/fluid  Bone/mineral  Metal

What density are the lungs? Why? The list: air, fat, soft tissue, mineral and metal

avb  The X-ray tube (X), housed in a ‘wall’ (1) rotates around a hole (2) in the wall. The detector (D) also rotates diametrically opposite the tube. The patient, lying on a sliding trolley (3) or a couch passes through the hole. The movement of the patient can be controlled so that ‘slices’ of the body are scanned by the apparatus X D

avb A P R L Liver Air in the stomach As the patient is supine, the air rises to the anterior side. Right kidney R. Psoas major R. post. Vertebral muscles Pancreas Left kidney Aorta Inf vena cava, with left renal vein crossing across the aorta Key Point : Recognition of major anatomical structures.  A CT image can be taken as a plain image or with the introduction of a contrast medium. Like conventional X-ray images, bone appears white, air black and soft tissues have intermediate densities depending on their composition and thickness. However, the contrast and resolution is better than in conventional tomography.

CT scan of the abdomen X-rays used skin What density is this? air

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avb  The grey or white appearance of fat is an indicator that this is an MR image. It evident as a thick layer in the abdominal wall. It is also easily recognizable around the kidneys (perineal fat) and in the greater omentum in front. Notice that the definition of soft tissue structures is sharper. F F F F Liver Spleen K K A P St Key Point : Fat is the key!

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avb  A number of highly sophisticated tools are available for imaging now. Some of them are still more of research tools, but may enter the field of routine diagnosis very soon. Last Slide