Babeh Edi

Introduction to Mammography

WHAT IS A MAMMOGRAM? A mammogram is a radiograph of the breast tissue (refer to the attached copy of a mammogram). It is an effective non-invasive means of examining the breast, commonly searching for breast cancer. Cancer is not preventable, but early detection leads to a much higher chance of recovery and lowers the mortality rate from this disease. Breast tissue composition varies with age and hormone levels in a woman. Generally, A younger woman has denser or fibro-glandular breasts. Her mammogram will look very white or "cloudy" (Figure 8-dense breast). Middle-aged women have a mixture of fibrous and glandular tissues (Figure 8-50-50 breast). Their mammograms look black and white. In a mature breast, most of the fibrous tissue is replaced with fatty tissue. The mammograms tend to look black or gray (Figure 8-Fatty Replaced breast) Film sizes 18 x 24 cm used for small to average sized breasts and 24 x 30 cm used for large sizes. Mammography Procedure Here is what happens, in brief : The Woman The woman is escorted to the changing room, where she undresses from the waist up and changes into the screening center gowns She is asked to wipe off any deodorants, perfumes or powders that she may have used that day, as these can mimic micro calcifications on the film She is taken into the mammography room, where the mammographer or technologist reviews her history sheet. The history sheet has questions pertaining to the woman’s previous mammograms, prior surgeries (if any), if she felt any lumps, superficial marks (such as prominent moles, scars from an incision), family history of breast cancer, number of children, her age when the first child was born, and last date of menstruation or post-menopausal (Addendum 2). Then, the mammography procedure is explained. This opens communication channels and the woman feels free to voice her concerns, thus increasing her comfort level. It is important to prepare the woman for the compression that would be used for imaging. This device causes discomfort, but should not hurt the woman. A Compression Paddle, (see Figure 6 and Figure 7) is a device used to compress the breast tissue. This helps to spread out and separate breast tissue, enabling the Radiologist to get an unobscured view of possible pathology. Compression also lowers patient radiation dose and prevents patient motion. The required views are performed and the woman is dismissed with instructions that she might feel sore for a day or so from the compression. The Machine Mammography equipment has progressed rapidly over the last 10 years. In developed countries, a dedicated mammography unit is used. A whole range of manufacturers make these machines, for example : GE, Bennett, Lorad, Siemens, Fischer, Phillips. They generally have a reciprocating grid to reduce scatter radiation thus avoiding fog and blurry image. The Filter (to make the beam hard and more penetrable) used, is 0.03 mm Molybdenum. Film Processing is done under specific conditions. The two ways to develop an exposed film are (1) Standard Processing and (2) Extended Processing. The choice depends on the type of film used. Technique used for a mammogram is low Kilo-voltage Peak (KvP) about 24 to 30. The milli-Ampere-seconds (mAs) varies depending on breast tissue density. When the photo timer cells are used, it provides the optimum mAs for the tissue to be imaged. This technique results in mammograms with a high film contrast, making it easier for the Radiologist to read. The Films used for mammography are single emulsion fast films to enhance image sharpness by eliminating geometric distortion. Films commonly used are : Kodak Min- RE, Agfa, Fuji, Dupont, Konica. The screens consist of a rare earth phosphor called terbium activated gadolinium oxysulfide. Screens have to be compatible with the film. The newest film-screen combination is responsible for dose reduction by 30 - 50 % . Markers are used to indicate the side and view demonstrated on that particular film. Markers are placed on the side of the axilla (armpit) of the patient. This acts as a reference point to understand the orientation of the breast, especially in the CC view. Views Screening Mammograms These views are done as a regular screening process to get an overall picture of the breasts and ensure that all is well. The protocol depends on the specific facility. In America, four films are required of the breasts: two views for each breast. In Europe, most countries do one view (MLO) of each breast and if an area of suspicion is notice, then 15% of the times, additional CC views are taken. Abbreviation Projection/Position Direction of the X-Ray CC Cranio-Caudal Direction from head (cranium) to the feet (caudal) MLO Medio-Lateral Oblique X-ray direction is from medial(inner) to lateral (outer) aspect; and the orientation of the breast is at an angle (Oblique) Alternate Views These are views done when the patient is unable to be positioned in certain views due to physical handicap or when the Radiologist wants to get a better look at possible pathology. Abbreviation Projection/Position Direction of the X-Ray LMO Lateral-Medial Oblique Direction of ray is from lateral(outer) to medial (inner), obliqued breast to demonstrate lesions in medial area 90LAT-LM 90LAT-ML   90 degree Lateral Direction of ray from one side to the other and the breast is in the lateral position Augmented Breast Views Regular views done and additional "Implant Displaced" (ID) Views performed. Regular views comprise of the screening views with minimal compression (too much compression can damage the implants) and ID views are the screening views with the implants pushed back against the chest wall and focus is on breast tissue only. Diagnostic Mammogram These views are to be used in addition to the screening mammograms to localize the exact position of an abnormality or views to better define the nature of an abnormality. Some abbreviations for those views are: ABBREVIATION MEANING M Magnification XCCL Cranio Caudal view eXaggerated to axilLa XCCM Cranio Caudal view eXaggerated Medially CV CleaVage AT Axillary Tail RM Rolled Medially RL Rolled Laterally ID Implant Displaced Interpreting Mammograms Reading mammograms is a challenge for Radiologists. Diagnosis is truly subject to interpretation. Hence the concept of a ‘second reader’ is catching on in USA. In Europe, a second reading is routine procedure. A powerful magnifying glass is used to get a better look at suspected pathology. The ideal reading condition is in a dark room with no lights other than the ones from behind the mammogram films (on a film viewer or a motorized film viewer). Usually, in the reading area, there is a ‘hot light’ which is more powerful, enabling the Radiologist to get a sharper view of suspected area. If required, the Radiologist can turn this on and hold the film in front of it. Radiologists read films as per certain criteria : They do a comparative study of current films and prior films. They look for tissue, structure and calcification changes. If for example, they see that the current films have more microcalcifications than the previous, the woman would be subject to additional views in order to visualize the suspicious areas. The Radiologists also do a comparative study of both the breasts. This is termed as an ‘ asymmetric study’. Generally, pathology does not occur in the both the breasts asymmetrically. Viewing the parenchymal pattern is another method used by many Radiologists to find some signs leading to the detection of small invasive tumors. Both the CC views are placed against each other and they look for asymmetry, which is indicative of tumors. Similarly, both the MLOs are compared. Other features they look for are: architectural distortion, comparison of the nipples and retroareolar areas. Work-up process If the Radiologist detects an area of suspicion, a series of work-up procedure is recommended. The criteria for their decision is based on what they see and the location. For example, in the course of ‘asymmetric study’ the Radiologist discovers a density, then he/she has to decipher if the pathologic abnormality is obvious (stellate lesion, typical/linear cancerous microcalcifications). If the answer is ‘Yes’, various procedure and modalities could be used (core biopsy or ultrasound), if it is ‘No’, then additional views such as spot compression can be performed to see if see if the density is an architectural distortion, fibrosis or normal parenchyma. Here is a table of ‘Protocol for Breast Cancer Screening Path’ :   © 2004 R2 Technology, Inc. Ref: From : http://www.r2tech.com/pti/index_b.html