Presentation on theme: "MAMMO QC – covered in week 8"— Presentation transcript:
1MAMMO QC – covered in week 8 MAMMOGRAPHYEquipment– Lecture #1Bushong Ch. 23MAMMO QC – covered in week 8Rev. Spring 2014
2PHANTOM IMAGES 4/5 masses 3/4specks 4/6 fibers should be seen WEEKLY - to assure film density, contrast, uniformity and image quality are optimum – Using the SAME cassette and technical factors each time4/5 masses3/4specks4/6 fibersshould be seen(see pg 500 review book)
3Mammography Equipment Bushong – Ch. 23 FILM SCREEN& DIGITALWhen 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.
4EQUIPMENT DIFFERENCES TARGET MATERIAL –MOLYBDENUMMO/RHODIUMSMALLER FOCAL SPOTSSHORTER SIDKVP RANGESLOW ~ 24 – – 28 (Bushong)(type of target used)MASPHOTOCELLS
5Mammography Imaging System High frequency generatorsTARGET MATERIAL:Tungsten (W), (z = ____?)Molybdenum (Mo), (z = ___ ?)or rhodium (Rh) target (z = ___ ?)Focal spot sizes 0.3/0.1 mm (Bushong)with tilted tubeMaximum 600 mAs limit
6Mammography Imaging System Inherent filtration 0.1 Al equivalentHeel effect used to advantageCompression reduces motion, improves spatial resolution, lowers patient doseHigh-transmission cellular gridAutomatic exposure control
7but improves contrast significantly p 327 A high-transmission cellular grid designed specifically for mammography.4:1 or 5:1 grid ratio40 line/cm frequency4:1 grid doubles pt dose –but improves contrast significantly p 327Correct way to load mammography film and position the cassette.Spatial resolution improves when the x-ray film is placed closest to the breast andbetween the x-ray tube and the radiographic intensifying screen.
8DEDICATED 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 PaddleHeel Effect (fat/cat)GRIDS : 4:1 or 5:1 (vs 8 to16:1)What does “DEDICATED”Mean in the above title?
9Anode Heel Effect –Which portion shouldBe under the cathodeSide of the TUBE?The heel effect can be used to advantage in mammography by positioning the cathode toward the chest wall to produce
10DIGITAL MAMMO DIGITAL has a resolution of approximately 5 lp/mm – but also has MORE CONTRASTCONVENTIONAL FILM/SCREEN: resolution of approximately 12 lp/mmNo need for an additional exposure to the patient
11MAMMOGRAPHIC IMAGESThe BREAST has a low subject contrast – little differences in density = soft tissue radiography
12Can affect: kVp & mAs ranges Compression in mammography has three principal advantages: improved spatial resolution, improved contrast resolution, and lower patient dose.Can affect:kVp & mAs ranges