Transcript TECHNIQUE CHARTS

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.
2.
3.
OPTIMUM kVp/VARIABLE mAs
VARIABLE kVp/FIXED mAs
AUTOMATED EXPOSURE CONTROL

FIXED kVp
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 kVp / VARIABLE mAs
1.
2.
3.
4.
ESTABLISHES A SPECIFIC kVp PER BODY PART.
THE mAs 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 kVp / FIXED mAs
1. kVp VARIES ACCORDING TO CM
MEASUREMENT.
1. 2 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.
2.
3.
FORM OF OPTIMUM kVp TECHNIC
kVp IS SET, mAs ADJUSTS ACCORDING TO AMT. OF
EXPOSURE RECEIVED BY IONIZATION CHAMBER OF
PHOTOCELLS.
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

70-80 kVp
T-SPINE


70-80 kVp
LAT. T-SPINE IS BEST IMAGED
WITH BREATHING TECHNIC.
(auto-tomography)
L-SPINE


70-80 kVp
90 kVp L5-S1
OPTIMUM kVp TECHNICS
HUMERUS,
SHOULDER,
SCAPULA

70-80 kVp
ELBOW

60-70 kVp
FOREARM

50-60 kVp
WRIST

50-60 kVp
HAND

50-60 kVp
FINGERS

50 kVp
OPTIMUM kVp TECHNIC
CHEST X-RAY

110-120 kVp
BARIUM STUDIES

SINGLE CONTRAST
110 kVp
DOUBLE CONTRAST
 90 kVp


KNEE

60-70 kVp
TIBIA FIBULA

60-70 kVp
ANKLE

60-70 kVp
FOOT

50-60 kVp
VARIABLE kVp TECHNICS
STANDARD RULE
1.
2.
3.
MEASURE BODY PART, MULTIPLY
MEASUREMENT BY 2.
ONCE MEASUREMENT IS ESTABLISHED,
ADD OR SUBTRACT 2 kVp FOR EACH cm.
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:


70 kVp @ 30 MAs
TO MODIFY CONTRAST
 70 X 15% =
 70 x .15 = 10.5
 70 kVp + or - 10.5 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.