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PublishDonald McDonald Modified over 9 years ago
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BONE DENSITOMETRY
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THE ART AND SCIENCE OF MEASURING THE BONE MINERAL CONTENT AND DENSITY OF SPECIFIC SKELETAL SITES OR THE WHOLE BODY.
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THE MOST VERSATILE AND WIDELY USED TECHNIQUE DUAL X-RAY ABSORPTIOMETRY DXA
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DXA ADVANTAGES LOW RADIATION DOSE WIDE AVAILABILITY EASE OF USE SHORT SCAN TIME HIGH RESOLUTION IMAGES GOOD PRECISION STABLE CALIBRATION
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DXA IS A SUBTRACTION TECHNIQUE- SOFT TISSUE STRUCTURES ARE ELIMINATED. X-RAY ATTENUATION OF THE BONE IS MEASURED. BONE MINERAL DENSITY IS CALCULATED (BMD)
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BMD
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DXA SCANS PROVIDE IMAGES FOR THE PURPOSE OF CONFIRMING THE CORRECT POSITIONING OF THE PATIENT AND CORRECT PLACEMENT OF ROI ( REGION OF INTEREST) IMAGES ARE NOT USED FOR DIAGNOSIS!! THE BONE DENSITY RESULTS ARE COMPUTED AND PRINTED BY SOFTWARE
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DXA COMPUTATIONAL SOFTWARE
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HISTORY OSTEOPOROSIS UNDETECTED AND OVERLOOKED UNTIL 1920s. THE FIRST PUBLICATION ABOUT BONE MASS APPEARED IN 1930s. RA- RADIOGRAPHIC ABSORPTIOMETRY- X-RAY TAKEN AND COMPARED TO A STANDARD RADIOGRAPH RADIOGAMMETRY – INTRODUCED IN THE 1960s IN RESPONSE TO THE MEASUREMENT OF A BONE LOSS IN ASTRONAUTS.
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IN 1970 CT WAS USED THROUGH THE SPECALIZED SOFTWARE. QUANTITATIVE CT. 1970s AND 1980s BROUGHT THE FIRST DEDICATED SCANNERS. FIRST SPA THEN DPA. USED RADIOISOTOPE AS A SOURCE OF RADIATION. FIRST COMMERCIAL DXA SCANNER INTRODUCED IN 1987 FIRST USED RADIOISOTOPE AS THE X-RAY SOURCE THEN REPLACED BY THE X-RAY TUBE. DXA OF THE HIP AND SPINE IS THE MOST ACCEPTED METHOD FOR MEASURING BONE DENSITY
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CT BONE DENSITOMETRY
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SPA SCANNER
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HIP AND SPINE DXA
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BONE BIOLOGY
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SKELETON PURPOSES BODY SUPPORT RED BLOOD CELLS MANUFACTURING MINERAL STORAGE
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BONE TYPES CORTICAL TRABECULAR- ( CANCELLOUS)
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BONE CROSS-SECTION
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CORTICAL BONE ACCOUNTS FOR 80% OF SKELETAL MASS IT SUPPORTS WEIGHT
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TRABECULAR BONE IS THE DELICATE LATTICE WITHIN THE BONE THAT ADDS STRENGTH
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SPECIFIC BONE 40% ORGANIC MATTER 60% BONE MINERAL DXA MEASURES THE DENSITY OF BONE MINERAL
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BONE IS CONSTANTLY GOING HROUGH THE REMODELING PROCESS
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PEAK BONE MASS AT THE AGE OF 30-35
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DECREASING BONE MASS STARTING AT THE AGE OF 50
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DECREASE IN BONE MASS PRONOUNCED IN WOMEN AT MENOPAUSE LOSS OF BONE PRESERVING ESTROGEN!
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OSTEOPOROSIS Osteoporosis, or "thin" bones, is a disease that gradually weakens bones, making them more fragile and likely to break. It is not a form of arthritis. Osteoporosis leads to an increase in certain types of fractures (broken bones), such as hip fractures, wrist fractures, and compression fractures of the spinal vertebrae (back bones )
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RISK FACTORS FOR OSTEOPOROSIS IN WOMEN MENOPAUSE SMALL BONE FRAME FAMILY HISTORY ADVANCED AGE LOW CALCIUM DIET INACTIVE LIFESTYLE CIGARETTE SMOKING GI MALABSORPTION PROBLEM CERTAIN MEDICATION USE- CORTICOSTEROIDS
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MINERAL CONTENT CALCULATION IN BONE DENSITOMETRY BMC = BMD X AREA
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DXA SYSTEMS PENCIL BEAM FAN BEAM
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PENCIL BEAM SCANNER
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FAN BEAM SCANNER
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