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 ENSURES QUALITY RESULTS CONTROLS COSTS REPRODUCIBLE IMAGES

PURPOSE B. IMAGE CONSISTENCY CONSISTENT QUALITY IMAGES CONTRAST MAINTENANCE APPROPRIATE DENSITY MAINTENANCE

CONSIDERATIONS A. CHOICE OF TECHNIQUE SYSTEMS 1. OPTIMUM kVp/VARIABLE mAs 2. VARIABLE kVp/FIXED mAs 3. AUTOMATED EXPOSURE CONTROL  FIXED kVp

CONSIDERATIONS B. PATIENT MEASUREMENTS 1. ESTABLISHES EXACT SCIENCE 2. SHOWS ACCURACY IN WORK PERFORMANCE

CONSIDERATIONS C. PROCESSING 1. PROCESSOR QUALITY ASSURANCE 2. HIGH TEMPERATURE 3. LOW TEMPERATURE 4. FILM FOG 5. IMPROPER WATER FLOW

TYPES OF TECHNIC CHARTS A. OPTIMUM kVp / VARIABLE mAs 1. ESTABLISHES A SPECIFIC kVp PER BODY PART. 2. THE mAs VARIES ACCORDING TO CM MEASUREMENT OF PART. 3. PRODUCES A CONTRAST CONSISTENCY FOR THE TECHNOLODIST AND RADIOLOGIST. 4. TRAINS THE TECHNOLOGISTS’ AND THE RADIOLOGISTS’ EYES TO VIEW RADIOGRAPHIC IMAGES.

TYPES OF TECHNIC CHARTS B. VARIABLE kVp / FIXED mAs 1. kVp VARIES ACCORDING TO CM MEASUREMENT kVp 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. FORM OF OPTIMUM kVp TECHNIC 2. kVp IS SET, mAs ADJUSTS ACCORDING TO AMT. OF EXPOSURE RECEIVED BY IONIZATION CHAMBER OF PHOTOCELLS. 3. POSITIONING, PHOTOCELL & BODY PART ALIGNMENT MUST BE EXTREMELY ACCURATE.

OPTIMUM kVp TECHNICS ABDOMEN PLAIN FILMS 70-80kVp SKULL FILMS 70-80kVp FEMUR 70-80kVp C-SPINE kVp T-SPINE kVp LAT. T-SPINE IS BEST IMAGED WITH BREATHING TECHNIC. (auto-tomography) L-SPINE kVp 90 kVp L5-S1

OPTIMUM kVp TECHNICS HUMERUS, SHOULDER, SCAPULA kVp ELBOW kVp FOREARM kVp WRIST kVp HAND kVp FINGERS 50 kVp

OPTIMUM kVp TECHNIC CHEST X-RAY kVp BARIUM STUDIES SINGLE CONTRAST  110 kVp DOUBLE CONTRAST  90 kVp KNEE kVp TIBIA FIBULA kVp ANKLE kVp FOOT kVp

VARIABLE kVp TECHNICS STANDARD RULE 1. MEASURE BODY PART, MULTIPLY MEASUREMENT BY ONCE MEASUREMENT IS ESTABLISHED, ADD OR SUBTRACT 2 kVp FOR EACH cm. 3. The kVp VARIES ACCORDING TO DESIRED CONTRAST

Automatic Exposure Control (AEC)/ Phototimer SAME AS OPTIMUM kVp TECHNIC

EXPOSURE CALCULATIONS 15 % kVp RULE (CONTRAST) NORMALLY TRANSLATES TO 8-12 kVp DIFFERENCE. PRIMARILY USED TO EFFECT CONTRAST. EFFECT IS: FILM CONTRAST CHANGES PRIMARILY AND ALSO CHANGES DENSITY AS A SECONDARY FACTOR.

EXPOSURE CALCULATIONS 30 % mAs RULE (DENSITY) NORMALLY TRANSLATES INTO DARKENING OR MAKING FILMS LIGHTER (OPTICAL DENSITY). IF kVp IS ACCURATE, mAs CHANGES TO MAKE RADIOGRAPHS VISIBLY LIGHTER OR DARKER. THE mAs MUST BE DECREASED BY HALF OR DOUBLED WITH ANY 15% CHANGE IN kVp. NORMALLY, IF A FILM IS TOO DARK OR TOO LIGHT, THE mAs MUST BE DECREASED BY HALF OR DOUBLED TO DEMONSTRATE A SIGNIFICANT CHANGE IN RADIOGRAPHIC DENSITY.

BASIC MATH CALCULATIONS EXAMPLE: MAs TO MODIFY CONTRAST  70 X 15% =  70 x.15 = 10.5  70 kVp + or kVp

BASIC MATH CALCULATIONS mAs CONVERSION 30 mAs X 30 % = 30 X.30 = 9 mAs 30 mAs + or - 9 mAs

References Bushberg et al, The Essentials of Physics and Medical Imaging, Williams & Wilkins Publisher. Bushong, S., Radiologic Science for Technologists, Physics, Biology and Protection, 8th 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, 8th Edition, Charles C. Thomas Publisher.