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MAMMOGRAPHY

Equipment – Lecture #1 Bushong Ch. 23. MAMMOGRAPHY. MAMMO QC – covered in week 8. Rev. Spring 2014. PHANTOM IMAGES. WEEKLY - to assure film density, contrast, uniformity and image quality are optimum – Using the SAME cassette and technical factors each time 4/5 masses 3/4specks

mark-lynch
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MAMMOGRAPHY

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  1. Equipment – Lecture #1 Bushong Ch. 23 MAMMOGRAPHY MAMMO QC – covered in week 8 Rev. Spring 2014

  2. PHANTOM IMAGES • WEEKLY - to assure film density, contrast, uniformity and image quality are optimum – Using the SAME cassette and technical factors each time • 4/5 masses • 3/4specks • 4/6 fibers • should be seen • (see pg 500 review book)

  3. FILM SCREEN & DIGITAL Mammography EquipmentBushong – Ch. 23 When the x-ray tube is tilted in its housing, the effective focal spot is small, the x-ray intensity is more uniform, and tissue against the chest is imaged.

  4. TARGET MATERIAL – MOLYBDENUM MO/RHODIUM SMALLER FOCAL SPOTS SHORTER SID KVP RANGES LOW ~ 24 – 30 23 – 28 (Bushong) (type of target used) MAS PHOTOCELLS EQUIPMENT DIFFERENCES

  5. Mammography Imaging System • High frequency generators • TARGET MATERIAL: • Tungsten (W), (z = ____?) 74 • Molybdenum (Mo), (z = ___ ?) 42 • or rhodium (Rh) target (z = ___ ?) 45 • Focal spot sizes 0.3/0.1 mm (Bushong) • with tilted tube • Maximum 600 mAs limit

  6. Mammography Imaging System • Inherent filtration 0.1 Al equivalent • Heel effect used to advantage • Compression reduces motion, improves spatial resolution, lowers patient dose • High-transmission cellular grid • Automatic exposure control

  7. A high-transmission cellular grid designed specifically for mammography. • 4:1 or 5:1 grid ratio • 40 line/cm frequency • 4:1 grid doubles pt dose – • but improves contrast significantly p 327 • Correct way to load mammography film and position the cassette. • Spatial resolution improves when the x-ray film is placed closest to the breast and • between the x-ray tube and the radiographic intensifying screen.

  8. DEDICATED MAMMOGRAPIC EQUIPMENT • KVP RANGE : 23 – 28 kvp (BUSHONG) • TARGETS: Molybdenum / Rhodium (vs. Tungsten) • FOCAL SPOTS • (can range from 0.1 – 0.6) • SID 60 –70 cm (vs. 100cm) • Compression Paddle • Heel Effect (fat/cat) • GRIDS : 4:1 or 5:1 (vs 8 to16:1) What does “DEDICATED” Mean in the above title?

  9. Anode Heel Effect – Which portion should Be under the cathode Side of the TUBE? The heel effect can be used to advantage in mammography by positioning the cathode toward the chest wall to produce

  10. DIGITAL MAMMO • DIGITAL has a resolution of approximately 5 lp/mm – but also has MORE CONTRAST • CONVENTIONAL FILM/SCREEN: resolution of approximately 12 lp/mm No need for an additional exposure to the patient

  11. MAMMOGRAPHIC IMAGES The BREAST has a low subject contrast – little differences in density = soft tissue radiography

  12. Compression in mammography has three principal advantages: improved spatial resolution, improved contrast resolution, and lower patient dose. Can affect: kVp & mAs ranges

  13. MAX 25 PSI - how is this measured?

  14. Most MAMMOS ARE NOW DIGITAL – NOT FILM SCREEN PROCESSING Position of AEC over breast tissue

  15. Remove all ambient light when possible – for better images

  16. Other Imaging of the Breast

  17. Breast Ultrasound What is best seen? Why is US chosen over X-Ray?

  18. CT Breast Scanner • Detect lesions 5mm in size • 1/10 of the radiation • 2-3 times higher spatial resolution

  19. 3d Mammo ?

  20. Breast MRI

  21. Mammo Images & Procedures in Lecture # 2

  22. Digital vs Film Image

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