
f32c5aedc897fff015f3c23224004e1a.ppt
- Количество слайдов: 21
TECHNIQUE CHARTS SERGEO GUILBAUD CLINICAL COORDINATOR
Abstract A combination of settings selected by the radiographer on the control panel to produce a desired effect on the radiograph. Radiographic Technic is inclusive of three (3) groups of factors: 1. Exposure Technic Factors: Kilovoltage, Milliampere, Exposure time, and Source-to-image receptor distance (SID). 2. Patient Factors: Patient thickness, and patient composition (fat vs. muscle). 3. Image Quality Factors: Optical density, contrast, detail and distortion. To produce quality radiographic images, the radiographer must be alert to the patients’ characteristics. Most importantly, the composition of the patient must be kept in mind; body part thickness, body part composition (fat vs. muscle). The production of high quality images requires a thorough understanding of the relationship between all of the aforementioned factors.
General 50% of all repeats are attributed to exposure errors. repeat radiographs cost the health care system $100 million annually.
PURPOSE A. STANDARDIZATION OF EXPOSURE TECHNICS n n n ENSURES QUALITY RESULTS CONTROLS COSTS REPRODUCIBLE IMAGES
PURPOSE B. IMAGE CONSISTENCY n n n CONSISTENT QUALITY IMAGES CONTRAST MAINTENANCE APPROPRIATE DENSITY MAINTENANCE
CONSIDERATIONS A. CHOICE OF TECHNIQUE SYSTEMS 1. 2. 3. OPTIMUM k. Vp/VARIABLE m. As VARIABLE k. Vp/FIXED m. As AUTOMATED EXPOSURE CONTROL w FIXED k. Vp
CONSIDERATIONS B. PATIENT MEASUREMENTS 1. 2. ESTABLISHES EXACT SCIENCE SHOWS ACCURACY IN WORK PERFORMANCE
CONSIDERATIONS C. PROCESSING 1. 2. 3. 4. 5. PROCESSOR QUALITY ASSURANCE HIGH TEMPERATURE LOW TEMPERATURE FILM FOG IMPROPER WATER FLOW
TYPES OF TECHNIC CHARTS A. OPTIMUM k. Vp / VARIABLE m. As 1. 2. 3. 4. ESTABLISHES A SPECIFIC k. Vp PER BODY PART. THE m. As VARIES ACCORDING TO CM MEASUREMENT OF PART. PRODUCES A CONTRAST CONSISTENCY FOR THE TECHNOLODIST AND RADIOLOGIST. TRAINS THE TECHNOLOGISTS’ AND THE RADIOLOGISTS’ EYES TO VIEW RADIOGRAPHIC IMAGES.
TYPES OF TECHNIC CHARTS B. VARIABLE k. Vp / FIXED m. As 1. k. Vp VARIES ACCORDING TO CM MEASUREMENT. 1. 2 k. Vp PER CM 2. RADIOGRAPHIC DENSITY REMAINS CONSTANT WHILE CONTRAST CHANGES. 3. SMALL LUCENCIES APPEAR & DISAPPEAR. 4. CONSTANT CHANGE IN CONTRAST
TYPES OF TECHNIC CHART C. AUTOMATIC EXPOSURE CONTROL (AEC) PHOTOTIMERS 1. 2. 3. FORM OF OPTIMUM k. Vp TECHNIC k. Vp IS SET, m. As ADJUSTS ACCORDING TO AMT. OF EXPOSURE RECEIVED BY IONIZATION CHAMBER OF PHOTOCELLS. POSITIONING , PHOTOCELL & BODY PART ALIGNMENT MUST BE EXTREMELY ACCURATE.
OPTIMUM k. Vp TECHNICS ABDOMEN n n PLAIN FILMS 70 -80 k. Vp SKULL FILMS n 70 -80 k. Vp FEMUR n 70 -80 k. Vp C-SPINE n 70 -80 k. Vp T-SPINE n n 70 -80 k. Vp LAT. T-SPINE IS BEST IMAGED WITH BREATHING TECHNIC. (auto-tomography) L-SPINE n n 70 -80 k. Vp 90 k. Vp L 5 -S 1
OPTIMUM k. Vp TECHNICS HUMERUS, SHOULDER, SCAPULA n 70 -80 k. Vp ELBOW n 60 -70 k. Vp FOREARM n 50 -60 k. Vp WRIST n 50 -60 k. Vp HAND n 50 -60 k. Vp FINGERS n 50 k. Vp
OPTIMUM k. Vp TECHNIC CHEST X-RAY n 110 -120 k. Vp BARIUM STUDIES n SINGLE CONTRAST n w 110 k. Vp DOUBLE CONTRAST w 90 k. Vp KNEE n 60 -70 k. Vp TIBIA FIBULA n 60 -70 k. Vp ANKLE n 60 -70 k. Vp FOOT n 50 -60 k. Vp
VARIABLE k. Vp TECHNICS STANDARD RULE 1. 2. 3. MEASURE BODY PART, MULTIPLY MEASUREMENT BY 2. ONCE MEASUREMENT IS ESTABLISHED, ADD OR SUBTRACT 2 k. Vp FOR EACH cm. The k. Vp VARIES ACCORDING TO DESIRED CONTRAST
Automatic Exposure Control (AEC)/ Phototimer SAME AS OPTIMUM k. Vp TECHNIC
EXPOSURE CALCULATIONS 15 % k. Vp RULE (CONTRAST) n n n NORMALLY TRANSLATES TO 8 -12 k. Vp DIFFERENCE. PRIMARILY USED TO EFFECT CONTRAST. EFFECT IS: FILM CONTRAST CHANGES PRIMARILY AND ALSO CHANGES DENSITY AS A SECONDARY FACTOR.
EXPOSURE CALCULATIONS 30 % m. As RULE (DENSITY) n n NORMALLY TRANSLATES INTO DARKENING OR MAKING FILMS LIGHTER (OPTICAL DENSITY). IF k. Vp IS ACCURATE, m. As CHANGES TO MAKE RADIOGRAPHS VISIBLY LIGHTER OR DARKER. THE m. As MUST BE DECREASED BY HALF OR DOUBLED WITH ANY 15% CHANGE IN k. Vp. NORMALLY, IF A FILM IS TOO DARK OR TOO LIGHT, THE m. As MUST BE DECREASED BY HALF OR DOUBLED TO DEMONSTRATE A SIGNIFICANT CHANGE IN RADIOGRAPHIC DENSITY.
BASIC MATH CALCULATIONS EXAMPLE: n n 70 k. Vp @ 30 MAs TO MODIFY CONTRAST w 70 X 15% = w 70 x. 15 = 10. 5 w 70 k. Vp + or - 10. 5 k. Vp
BASIC MATH CALCULATIONS m. As CONVERSION n n n 30 m. As X 30 % = 30 X. 30 = 9 m. As 30 m. As + or - 9 m. As
References Bushberg et al, The Essentials of Physics and Medical Imaging, Williams & Wilkins Publisher. Bushong, S. , Radiologic Science for Technologists, Physics, Biology and Protection, 8 th Edition, C. V. Mosby Company. Carlton et al, Principles of Radiographic Imaging, An Art and Science, Delmar Publishing. Selman, J. , The Fundamentals of X-Ray and Radium Physics, 8 th Edition, Charles C. Thomas Publisher.
f32c5aedc897fff015f3c23224004e1a.ppt