Radiography Technique

1. Radiographic Technique 1
Prepared by:
Behzad Ommani
Bachelor of Radiology
Master of Medical Engineering
September, 2011

2. Image Receptor

3. Image Receptor
• In Radiography the image receptor (IR) is the device
that receives the energy of the x-ray beam and forms the
image of the body part.
1. Cassette with film
2. Image plate (IP)
3. Direct radiography (DR)
4. Fluoroscopic screen

4. • Device that contains special screens that glow when struck
by x-rays and imprints the x-ray image on film.
• The use of a darkroom is required where the film is
developed in a processor.
• Afterward the radiographic film image is ready for
viewing on an illuminator.
Cassette and Film

5. • Device similar to a cassette that contains special
phosphorus that store the x-ray image. The IP is inserted
into a reader device, which does not require a
darkroom.
• The Radiographic image is then converted to digital
format and is viewed on a computer monitor or printed
out on film
Image Plate

8. Digital Radiography
• Does not use a Cassette or an IP.
•A Flat Panel Detector built into the x-ray table or device
captures the x-ray image and converts it into digital format.
The image is then viewed on a computer monitor or printed
out on film.

9. The x-rays strike a fluoroscopic screen where the image is
formed and the body part is transmitted to a television
monitor via a camera.
This is a "real-time" device in which the body part is viewed
live on a television.
Fluoroscopic screen

10. Radiograph

11. Radiograph
Superimposition
• The relationship of the anatomic superimposition to
size, shape, position, and angulation must be reviewed.
Optical Density (OD)
Also known as the degree of film blackening, the optical
density of the radiograph must be within a diagnostic
range. If a radiograph is too light or dark, an accurate
diagnosis becomes difficult or impossible.
• If a change in technique is necessary. each of the
following primary factors controlling density must b.e
considered:

12. Milliampere-second (mAs)
• Milliamperage (mA) .
• Exposure time (second) .
Radiograph

13. Contrast
• The contrast, or the difference in density between any
two areas on a radiograph, must be sufficient to allow
radiographic distinction of adjacent structures with
different tissue densities.
• A wide range of contrast levels is produced among the
variety of radiographic examinations performed.
• A Low-contrast image displays many density levels, and
a Highcontrast image displays few density levels.
Radiograph

14. • The primary controlling factor of radiographic contrast
is kilovoltage peak (kVp).
Radiograph

15. Photoelectric
Compton
Coherent
1008060402010080604020

16. 0
1
2
3
4
5
6
20 40 60 80 100 20 40 60 80 100
Water
Bone
X-RayMassAttenuationCoefficients
KVP

17. Magnification
• The magnification of the body part must be evaluated,
taking into account the controlling factors of :
• Object-to-Image Receptor Distance (OID)
• Source-to-Image Receptor Distance (SID)
• All radiographs yield some degree of magnification
because all body parts are three dimensional.

18. Source-to-Image Receptor Distance
• This distance is a critical component of each radiograph
because it directly affects magnification of the body part
and the recorded detail.
• The greater the SID, the less the body part is magnified
and the greater the recorded detail will be.
• A SID of 40 inches (102 cm) traditionally has been used
for most conventional examinations.
• In recent years, however, the SID has increased to 48
inches (122 cm) in some departments.

19. Source- to-Skin Distance
The distance between the radiography tube and the skin of
the patient is termed the source-to-skin distance (SSD).
This distance affects the dose to the patient and is regulated
by the National Council on Radiation Protection (NCRP).
The current NCRP regulations state that the SSD shall not
be less than 12 inches (30 cm) and should not be less than
15 inches (38 cm).

20. Anatomical
Position & Markers

21. Anatomic Position
• The anatomic position refers to the patient
standing erect with the face and eyes directed
forward, arms extended by the sides with the
palms of the hands facing forward, heels
together, and toes pointing anteriorly.

22. Posteroanterior
• illustrates the anterior (front) aspect of the patient's
chest placed closest to the IR for a posteroanterior (PA)
projection.

23. Anteroposterior
• illustrates the posterior (back) aspect of the patient's
chest placed closest to the IR for an anteroposterior
(AP) projection.

24. Lateral
• Lateral radiographs are obtained with the patient's right
or left side placed against the IR.

25. Oblique
• Oblique radiographs are obtained when the patient's
body is rotated so that the projection obtained is not
frontal, posterior, or lateral

26. Decubitus
• In radiographic positioning terminology, the term
decubitus indicates that the patient is lying down and
that the central ray is horizontal and parallel with the
floor.
• Three primary decubitus positions are named according
to the body surface on which the patient is lying: lateral
decubitus (left or right), dorsal decubitus, and ventral
decubitus.

27. Anatomic Markers
Basic marker conventions include the following:
1. The marker should never obscure anatomy
2. The marker should never be placed over the patient's
identification information
3. The marker should always be placed on the edge of the
collimation border
4. The marker should always be placed outside of any
lead shielding

28. Specific marker placement rules
For AP and PA projections that include both the R and L
sides of the body.
 (Head, Spine, Chest. Abdomen. and Pelvis), a R marker is
typically used.
For lateral projections of the head and trunk, always mark
the side closest to the IR. For example, if the left side is
closest use a L marker. The marker is typically placed
anterior to the anatomy.
 (Head, Spine, Chest. Abdomen, and Pelvis)
For limb projections that are done with two images on one
IR. only one of the projections needs to be marked.

30. For limb projections, use the appropriate R or L marker.
The marker must be placed within the edge of the
collimated x-ray beam.
For oblique projections that include both the R and L sides
of the body (Spine, Chest. and Abdomen) the side down,
or nearest the IR is typically marked. For example, for a
right posterior oblique (RPO) position, mark the R side.
Specific marker placement rules

31. • For Decubitus positions of the chest and abdomen, the R
or L marker should always be placed on the side up
(opposite the side laid on) and away from the anatomy
of interest.
• For AP. PA ,or oblique chest projections, the marker is
placed on the upper outer corner so the thoracic
anatomy is not obscured.
• For limb projections where both the Rand Lsides are
imaged side-by-side on one IR (e.g. R and L AP knees)
both the R and L markers must be used to clearly
identify the two side.
Specific marker placement rules

32. English-Metric
Conversion and Film Sizes

33. English-Metric Conversion
• The following information is provided to assist the
radiographer in converting measurements from the
English system to the metric system and vice versa:
• 1 inch = 2.54 centimeters (cm)
• 1 cm = 0.3937 inch
• 40 inch SID = 1 meter (m) (approximately)

34. Film Sizes
• These sizes are subject to modification as needed to fit the
size of the body part.

35. Film Sizes

36. Patient Protection

37. Collimation of X-Ray Beam
The beam of radiation must be narrow enough to irradiate
only the area under examination.
This restriction of the x-ray beam serves two purposes :
• First, it minimizes the amount of radiation to the patient
and, reduces the amount of scatter radiation that can
reach the IR.
• Second, it produces radiographs that demonstrate
excellent recorded detail and increased radiographic
contrast by reducing scatter radiation, thereby
producing a shorter scale of contrast, and preventing
secondary radiation from unnecessarily exposing
surrounding tissues, with resultant image fogging

38. Gonad Shielding
The Center for Devices of Radiological Health has
developed guidelines recommending gonad shielding in
the following instances :
• If the gonads lie within or close to the primary x-ray
field (about 5 cm from) despite proper beam limitation.
• If the clinical objective of the examination is not
compromised .
• If the patient has a reasonable reproductive potential

39. Gonad Shielding

40. Motion

41. Motion and Its Control
• Patient motion plays a large role in radiography.
Because motion is the result of muscle action, the
radiographer needs to know some information about the
functions of various muscles.
• The three types of muscular tissue that affect motion are
the following:
1. Smooth (involuntary) .
2. Cardiac (involuntary) .
3. Striated (voluntary) .

42. Motion and Its Control
• Involuntary motion is caused by the following:
1. Heart pulsation
2. Chill
3. Peristalsis
4. Tremor
5. Spasm
6. Pain
• The primary method of reducing involuntary motion is to
control the length of exposure time-the less exposure
time to the patient, the better.

43. • Voluntary motion resulting from lack of control is
caused by the following:
1. Nervousness
2. Discomfort
3. Excitability
4. Mental illness
5. Fear
6. Age
7. Breathing
• The radiographer can control voluntary patient motion
by the following:
• Giving clear instructions
• Providing patient comfort
• Adjusting support devices
• Applying immobilization
Motion and Its Control

44. Operating Room
• The radiographer should perform hand washing and
wear scrub clothing, a scrub cap, and a mask and
should survey the particular setup in the operating room
before taking in the x-ray equipment.

45. Centers for Disease Control and Prevention
Health care workers should wear gloves whenever they
come into contact with blood, mucous membranes,
wounds, and any surface or body fluid containing blood.
Health care workers must be cautious to prevent needle
stick injuries.

46. Identification of Radiographs
All radiographs must to include the following information:
1. Date
2. Patient's name or identification number
3. Right or left marker
4. Institution identity
 Other patient identification markings may include the
patient's age or date of birth, time of day, and the name
of the radiographer or attending physician.

47. Identification of Radiographs

48. Filter
George E. Pfahler MD, the “Father of American
Radiotherapy”, was the first professor of Radiology at
the University of Pennsylvania School of Medicine.
• First 1950
• Leather shoe to become wet all over

49. • Filter Type :
Trough
Boomerang
Ferlic
Spertech Wedge
• Filter Composition :
Al
Clear Pb
Plastic
Filter

50. Filter