MAMMOGRAPHIC EQUIPMENT by SAROJ POUDEL NMCTH.pptx

for radiology student.
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1. MAMMOGRAPHIC EQUIPMENT Presented by : Saroj Poudel BSC.MIT 2 nd batch NMCTH

2. INTORODUCTION: The x-ray imaging of breast organ is called mammography. It is basically a soft tissue radiography in which the tissues have similar effective atomic number and mass density. Two types of mammography Screening mammography Diagnostic mammography

3. Breast cancer is the 2 nd leading cause of death from cancer in women(1 st is lung cancer). Breast cancer is very treatable, if detected early enough. Mammography is one of the most important innovations in the fight against breast cancer X-ray mammography has proved to be an accurate and simple method of detecting breast cancer, but it is not simple to perform. Can visualize microcalcification which is the only symptom of intraductal carcinoma.

4. History In 1913, radiographic appearance of breast cancers was first reported 1950’s – Industrial grade x-ray film used 1960’s – Xerography introduced –which has much lower dose 1966-first dedicated mammography equipment 1975 – High speed/resolution film introduced by DuPont 1992 – MQSA implemented  

5. Component of Mammography Mammography x-ray tube Generator Target material Focal spot Filtration Collimator Compression paddle Grids AEC (Automatic exposure control)

6. Mammography x-ray tube Mammography x-ray tube produces only characteristic x-ray. Low kVp is used (20 – 35 kVp for good contrast) Because it minimizes the Compton scattering and maximizes the photoelectric effect.

7. X-ray Generator High voltage generator The x-ray generator transforms the incoming voltage to the x-ray tube for production of the x-ray 20 – 40 kVp of x-ray energy is required for good contrast The high frequency generator with 5- 10 KHz power is used in mammography

8. Target material Target material consists of three main types : Molybdenum Rhodium Specialized tungsten Molybdenum is the most common anode target material used in mammography x-ray tubes. Molybdenum produces low kVp radiation (30 – 40 kVp ) Molybdenum and rhodium filters are more suitable for mammography machines. Tungsten and rhodium are used for higher beam needs, in dense breast tissues.

9. The mammography X-ray spectrum Traditional film-screen mammography relies on the spectrum from a Molybdenum (Mo) target with a Mo filter for small to average sized breast (up to about 50-60 mm) Alternative filters such as Rhodium (Rh) can be used for thicker breasts, and some (but not many) systems use a Rh target as well Tungsten targets are also used for thicker breasts, but in conjunction with the Rh filter (not Al like general radiography) W/Rh is also primary target filter combination in digital systems (plus some other filters such as silver and very thin aluminium) But Mo and Rh still favoured by some vendors

10. FOCAL SPOT Focal spot sizes range from 0.3 to 0.4 mm for non-magnification (contact) imaging, and from 0.1 to 0.15 mm for magnification imaging Focal spot and central axis are positioned over the chest wal l at the image receptor edge A reference axis, which typically bisects the field, is used to specify the projected focal spot size

11. Filtration Molybdenum or Rhodium filter is used and, This material are placed in the path of the x-ray beam in order to absorb those x-ray with energies above and below the desired spectrum Thin beryllium window or borosilicate window is used In case of, Rhodium target x-ray tube, Rhodium filter of 0.025 mm is used which give high quality x-ray with high penetration For tungsten target x-ray tube, molybdenum filter of 0.03 mm is used for lower kvp technique (below30kvp)

12. HEEL EFFECT Shape of the breast requires higher intensity of radiation near the chest wall, to create uniform exposure to the screen film The cathode is positioned toward the chest wall and the anode is towards to nipple By which the intensity of radiation near chest wall increases where greater penetration is needed Orientation of the tube in this fashion also decreases the equipment bulk near the patient’s head for easier positioning

13. COLLIMATION/CONE It is used to shape the radiation field Provide the smaller radiation field and less scatter Smaller exposed area provides better low patient dose X-ray beam is collimated by means of cone which produces D-shaped field.

14. COMPRESSION PADDLE Breast compression is required in all mammography examination Compression paddle attached to the machine which can be motor driven 1-4 mm thick plastic plate Amount of compression is between 25-40 pounds of pressure

15. BREAST SUPPORT PLATE It is the plate that hold the breast It has two part Upper part :- made from carbon fiber Lower part :- made from lead

16. Advantages Provides immobilization of the part during exposure Improve the contrast / image quality Reduced blurring from patient motion Reduces the scattered radiation Decreases the thickness of the breast Better visualization of the tissues near the chest wall Reduces tissue overlap and improve resolution

17. Grids Grid is used to reduce the scatter radiation reaching to the film It is placed between the screen and the film Most system have a moving grid with a ratio of 4:1 to 5:1 Frequency of grid id 40 lines/cm is used

18. High-transmission cellular (HTC) grid It is unique grid developed specifically for mammography provides scatter rejection in two dimensions Grid stripes are made of copper Interspace material is air Its physical dimension is 3.8:1 grid ratio

19. AUTOMATIC EXPOSURE CONTROL AEC system employes phototimers to measure the x-ray intensity and quality It is kept closer to the image receptor to minimize the object to image receptor distance and improve spatial resolution Its types are: Ionization chamber type Solid state diode type

20. MAGNIFICATION MAMMOGRAPHY It is referred to as macroradiography It produces twice the size of the normal image. Purpose of magnification mammography is to examine in depth the small, suspicious lesions or microcalcification seen in the normal mammogram. It should not be used routinely because it approximately doubled the patient dose

21. SCREEN FILM SYSTEM Four types of image receptor have been used for x-ray mammography: Direct-exposure film Xeroradiography Screen film Digital detectors Only screen film and digital detector are used today

22. The x-ray film should have high resolution and small grain size and used along with single intensifying screen The emulsion surface of the film must face the screen, To prevent loss of resolution due to light diffusion in the screen Gadolinium oxysulfide activated with terbium is used as screen phospor

23. DIGITAL MAMMOGRAPHY Detector is a flexible plastic coated with photostimulable x-ray absorbing phosphor material. The electronic charges are stored in “traps” in the material of phosphor. The image is then read by scanning of imaging plate by a laser beam. The resulting signal is logarithmically amplified , digitized and processed for film or soft copy display. The imaging plate is erased by exposure to white light.

24. Digital Mammographic Detectors X-ray to digital information. “DIRECT” conversion - Amorphous selenium (direct conversion) using (TFT) flat panel technology ~70 micron pixels “INDIRECT” conversion - Scintillating phosphor ( CsI columns) on an array of amorphous silicon photodiodes using thin-film transistor (TFT) flat panel technology ~100 micron pixels

25. Mean Glandular Dose The mean glandular dose (MGD) is an estimate of the average absorbed dose to the glandular tissues of a breast during mammography. It is measured in Gray ( Gy ). It is given by , MGD = Kgds standard breast (defined as 4.2 cm thick when compressed, with a 50:50 ratio of glandular tissue to fat), the MGD is typically 2 mGy per view. For full-field digital mammography systems, the dose is lower, typically from 1.2 to 1.8 mGy per view.

26. Recent Advancements And Modalities Contrast Enhanced Digital Mammography Breast Tomosynthesis Computerized Tomography Laser Mammography Scintimammography Optical mammography Positron Emission Mammography Breast Ultrasound Breast MRI

27. REFRENCES Radiologic science for technologists, 10 TH edition Chesney equipment Various web-sites

28. This Photo by Unknown Author is licensed under CC BY-NC

29. NEXT PRESENTATION : FLUROSCOPIC EQUIPMENT AND IIT BY NISHAN DHAKAL

30. Contrast Enhancement Digital Mammography CEDM is a recent development of digital mammography using the intra-venous injection of an iodinated contrast agent in conjunction with a mammography examination. is being used sparsely for cancer staging or neoadjuvant follow-up in places where MRI may not be available. This technique can increase mammographic lesion conspicuity.

31. Two techniques have been developed to perform CEDM examinations – Temporal Subtraction : Done by acquisition of high-energy images before and after contrast medium injection. The temporal subtraction technique offers the possibility to analyze the kinetic curve of enhancement of breast lesions. Dual-energy takes advantage of the difference in the atomic density of tissue, as compared to the contrast. Two images are acquired, and the low-density breast tissue is subtracted; however, the high energy of contrast persists, allowing any enhancing abnormality to be more visible.

32. The main disadvantages of this technique are that only a single breast can be imaged and patients have to maintain a particular position (usually MLO) for a prolonged period Dual Energy CEDM technique based on dual-energy acquisitions, where two images are acquired using distinct low-energy (standard mammography kV and filtration) and high-energy (higher kV with strong filtration) X-ray spectra.

33. The differences between X-ray attenuation of iodine and breast tissues at these two energy levels are exploited to suppress the background breast tissue. Dual-energy CEDM depicts areas in the breast associated with increased vascularity 2 min after the start of contrast injection that images are acquired.

34. Breast Tomosynthesis Also known as 3D mammography. Its an extension of digital mammography Breast tomosynthesis is a new tool that is based on the acquisition of three-dimensional digital image data, could help solve the problem of interpreting mammographic features produced by tissue overlap. In breast tomosynthesis, a moving x-ray source and a digital detector are used.

35. The x-ray tube in a breast tomosynthesis system moves along an arc during exposure. An arc like linear motion is suitable for imaging of breast tissue because most normal anatomic structures in the breast are oriented from the chest wall to the nipple. A wider angular range allows a thinner reconstructed section thickness of the in-focus plane because objects in the different planes are less blurred on images acquired at a smaller angle.

36. Normal glandular tissues are more clearly depicted on the breast tomosynthesis image (arrows in a) than on the digital mammogram (b). Normal lactiferous ducts are more prominently depicted on the breast tomosynthesis image (arrows in a) than on the digital mammogram (b).

37. Advantages it has the same advantages as that of FFDM. Better depiction of the smallest calcifications, better delineation of the lesion border requires less compression than 2D mammography. Disadvantages Motion artifacts are more likely to occur Large calcifications cause significant artifacts .

38. Computerized Tomography Laser Mammography Is an optical tomographic technique for breast imaging. uses laser energy in the near infrared region of the spectrum, to detect angiogenesis in the breast tissue It is optical molecular imaging for hemoglobin both oxygenated and deoxygenated. laser beams travel through tissue and suffer attenuation then a laser detector measures the intensity drop and the data is collected as the laser detector moves across the breast creating a tomography image. is able to recognize malignant tumor from benign lesion

39. Scintimammography Scintimammography , also known as nuclear medicine breast imaging, (Breast Specific Gamma Imaging (BSGI) or Molecular Breast Imaging (MBI). Done in those who had abnormal mammograms, or for those who have dense breast tissue, postoperative scar tissue or breast implants. Patient receives an injection of a small amount of a radioactive substance called technetium 99 sestamibi , which is taken up by cancer cells, and a gamma camera is used to take pictures of the breasts.

40. The procedure is less accurate in evaluating abnormalities smaller than one centimeter. Patient is exposed to slightly more radiation than mammography but has higher sensitivity and positive predictive value than conventional mammography.

41. Optical Mammography Diffuse optical imaging is a set of non-invasive imaging modalities that use near-infrared light then applies an algorithm to interpret the image and information. The technique can measure differences in water and fats. The tool creates real-time images of metabolic changes, allowing the differentiation between oxygen rich and oxygen-poor tissue and varying levels of hemoglobin through differences in light absorption. comparatively more comfortable with much less breast compression compared to conventional mammography.

42. Positron Emission Mammography PEM has higher resolution and a more localized field of view ,performed on patients to stage a newly diagnosed malignancy. uses a pair of dedicated gamma radiation detectors placed above and below the breast and mild breast compression to detect coincident gamma rays after administration of fluorine-18 fluorodeoxyglucose (18F-FDG) cancer cells demonstrate increased utilization of glucose. Through use of isotope fluorine-18 attached to the delivery compound deoxyglucose to produce the radiopharmaceutical 18F-FDG, this utilization of glucose can be visualized.

43. Advantages such as better delineation of lesion, high positive predictive value for malignancies and effective in follow up or in planning for RT (RADIATION THERAPY) Has higher radiation exposure

44. Breast Ultrasound Breast ultrasound is an important modality in breast imaging. The use of breast ultrasound: evaluate young (usually under 30 years of age) or pregnant patients who are symptomatic evaluate a palpable lump with negative or equivocal mammographic findings detect lesions in lower contrast field

45. help to distinguish between benign vs malignant characteristics guiding biopsy evaluate breast implants for rupture reasonable sensitivity but poor specificity may have a place in screening women at high risk or with mammographically-dense breasts Probe : linear array of high frequency linear transducer 7-13 MHz

46. Breast MRI It is a valuable tool to diagnose additional cancer in the same breast in up to one third of patients and is recommended as a supplemental screening tool to mammography in women considered to be at high risk for developing breast cancer. MRI is more sensitive in detection of invasive lobular cancer, Dedicated bilateral breast surface coil (simultaneous examination of both breasts) Preoperative MRI more accurate in assessing tumor extent and multi-focality (incl. DCIS)

47. MRI lowest FN rate in detecting Invasive lobular carcinoma, highest accuracy in measuring the size MRM could detect extensive intraductal component (EIC): sensitivity 71%, specificity 85%, accuracy 76% Pitfalls MRI typically costs more and takes more time to perform than other imaging modalities. MRI persistently underestimate minimal residual disease

48. This Photo by Unknown Author is licensed under CC BY-NC

49. MAMMOGRAPHY ADVANTAGEOUS OR DISADVANTAGEOUS? Mortality risk from mammography induced radiation is 5 deaths/ 1 million patients using screen film mammography It is more risky to refuse mammography than to allow it

50. FFDM Differences Image acquisition and display are separated Wide dynamic range Lower Dose (~20%) Same dose limits as for film-screen Higher kVp (+3 kVp ) Better for dense breasts Imaging detector can be used as AEC detector Use of Mo/Mo, Mo/Rh, Rh/Rh, W/Rh and W/Ag targets

51. For CR, the film-screen cassette is replaced with a photostimulable phosphor plate cassette Digital images Require workstations Post-processing image enhancement Computer aided diagnosis

52. Questions What is mammography? Why low kvp is used in mammography? What age should a woman get a mammogram? What is k-edge absorption? Why small focal spot is used in mammography? Advantages of compression in mammography. What is the main indication for magnification mammography? Name the three materials used for mammographic x-ray tube targets. Why cellular grid is used in mammography? 57

53. What is mammography? The x-ray imaging of breast organ is called mammography. It is basically a soft tissue radiography in which the tissues have similar effective atomic number and mass density. Why low kvp is used in mammography? Low kvp is used to maximize the photoelectric effect and thereby enhance differential absorption and improve contrast resolution. What age should a woman get a mammogram? Women ages 40 to 44 should have the choice to start annual breast cancer screening with mammograms. Age 45 to 54 should get mammograms every year and above 55 should get mammograms every 2 years, or can continue yearly screening. 58

54. What is k-edge absorption? In x-ray absorption spectroscopy, the k-edge is a sudden increase in x-ray absorption occurring when the energy of the x-rays is just above the binding energy of the innermost shell of the atoms interacting with the photons. Why small focal spot is used in mammography? The focal spots are generally smaller than for other x-ray procedures because of the requirements for minimal blurring and good visibility of detail to see the small calcification. Advantages of compression in mammography. Provides immobilization of the part during exposure Improve the contrast / image quality Reduced blurring from patient motion Reduces the scattered radiation Decreases the thickness of the breast Better visualization of the tissues near the chest wall Reduces tissue overlap and improve resolution 59

55. What is the main indication for magnification mammography? Magnification mammography is used to improve diagnostic accuracy, especially in the evaluation of microcalcification , by imaging a particular region of the breast. Name the three materials used for mammographic x-ray tube targets. The three materials used for mammographic x-ray tube target are molybdenum, Rhodium and Tungsten. Why cellular grid is used in mammography? The cellular grid is used in mammography because it provides scatter rejection in two dimensions. 60