Bone densitometry
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BONE DENSITOMETRY. BONE DENSITOMETRY. THE ART AND SCIENCE OF MEASURING THE BONE MINERAL CONTENT AND DENSITY OF SPECIFIC SKELETAL SITES OR THE WHOLE BODY. THE MOST VERSATILE AND WIDELY USED TECHNIQUE. DUAL X-RAY ABSORPTIOMETRY DXA. DXA. DXA ADVANTAGES. LOW RADIATION DOSE WIDE AVAILABILITY

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BONE DENSITOMETRY

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BONE DENSITOMETRY


BONE DENSITOMETRY

  • THE ART AND SCIENCE OF MEASURING THE BONE MINERAL CONTENT AND DENSITY OF SPECIFIC SKELETAL SITES OR THE WHOLE BODY.


THE MOST VERSATILE AND WIDELY USED TECHNIQUE

  • DUAL X-RAY ABSORPTIOMETRY

    DXA


DXA


DXA ADVANTAGES

  • LOW RADIATION DOSE

  • WIDE AVAILABILITY

  • EASE OF USE

  • SHORT SCAN TIME

  • HIGH RESOLUTION IMAGES

  • GOOD PRECISION

  • STABLE CALIBRATION


DXA

  • IS A SUBTRACTION TECHNIQUE- SOFT TISSUE STRUCTURES ARE ELIMINATED. X-RAY ATTENUATION OF THE BONE IS MEASURED. BONE MINERAL DENSITY IS CALCULATED

    (BMD)


BMD


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 COMPUTEDAND PRINTED BY SOFTWARE


DXA COMPUTATIONAL SOFTWARE


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.


  • 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


CT BONE DENSITOMETRY


SPA SCANNER


HIP AND SPINE DXA


BONE BIOLOGY


SKELETON PURPOSES

  • BODY SUPPORT

  • RED BLOOD CELLS MANUFACTURING

  • MINERAL STORAGE


BONE TYPES

  • CORTICAL

  • TRABECULAR- ( CANCELLOUS)


BONE CROSS-SECTION


CORTICAL BONE ACCOUNTS FOR 80% OF SKELETAL MASSIT SUPPORTS WEIGHT


TRABECULAR BONE IS THE DELICATE LATTICE WITHIN THE BONE THAT ADDS STRENGTH


SPECIFIC BONE

  • 40% ORGANIC MATTER

  • 60% BONE MINERAL

DXA MEASURES THE DENSITY

OF BONE MINERAL


BONE IS CONSTANTLY GOING HROUGH THE REMODELING PROCESS


PEAK BONE MASS AT THE AGE OF 30-35


DECREASING BONE MASS STARTING AT THE AGE OF 50


DECREASE IN BONE MASS PRONOUNCED IN WOMEN AT MENOPAUSELOSS OF BONE PRESERVING ESTROGEN!


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)


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


MINERAL CONTENT CALCULATION IN BONE DENSITOMETRY

BMC = BMD X AREA


DXA SYSTEMS

  • PENCIL BEAM

  • FAN BEAM


PENCIL BEAM SCANNER


FAN BEAM SCANNER


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