Radiographic positions and procedures
By
Mr.souheil Barakat, Radiographic
2011
Contents
- Basic terms,
- Chest , lungs,
- Trachea,
- Bronchography,
- Nasophrayngography (for adenoid).
- Pharyngography.
- Positive – contrast pharyngography.
Radiographic positions and procedures
Basic terms
1) Body positions: Body positions are the manner in which the patient is placed in relation to the surrounding space.
a) Decubitus : position assumed in lying down; the position assumed is described according to dependent body surface:
· Dorsal decubitus: supine or lying on back.
· Ventral decubitus: prone or lying face down
· Right lateral decubitus: lying on right side
· Left lateral decubitus: lying on left side.
b) Standing position
c) Seated position
2) Positioning terms:
a) Projection:
Projection usually describes the path of radiation as it goes from the x-ray tube through the patient to the image receptor.
b) View:
View describes the representation of an image as seen from the vantage of the image receptor.
c) Method:
Some radiologic procedures are named after individuals (for example, chassard-lapine or Towne) in recognition of their having developed a method to demonstrate a specific anatomic part.
3) Projection terminology:
a) Frontal projections (AP or PA):
- AP (anteroposterior) projection :the x-ray beam is shown entering the front (anterior ) body surface and exiting the back (posterior) surface.
- PA (posteroanterior) projection:The central ray entering from the posterior body surface .
b) Lateral projections: Lateral projections are always named by the side of the patient that is placed closest to the film (Right or left lateral projection).
c) Oblique projections: The term oblique refers to a position in which the body part is rotated so that it does not produce a frontal ( AP or PA) or a lateral projection. Oblique projections could be :RAO or LAO in prone position and RPO/ LPO in supine .
-In supine position :
- LPO ( left anteroposterior oblique) : the patient is rotatd, So that the left side
of the body is closest to the film .
- RPO (right anteroposterior oblique) : the patient is rotated, So that the right
side of the body is closest to the film.
-In prone position:
- RAO (right posteroanterior oblique) : the right side of the patient is closest to
the film.
- LAO (left posteroanterior oblique) : the left side of the patient is closest to the
film.
d) Decubitus projections:
- Decubitus projections are so named to indicate that the patient is lying down.
- Similar to lateral and oblique position, decubitus positions are named by the body surface on which the patient is lying.
- Dorsal decubitus : patient is lying on his back.
- Ventral decubitus : patient is in prone position.
- Right lateral decubitus : patient is lying on the right side of the body laterally.
- Left lateral decubitus : patient is lying on the left side of the body laterally.
e) Tangential projection: A tangential projection is one in which the central ray skims between body parts to profile a bony structure and project it free of superimposition.
f) Axial projections: In an axial projection there is longitudinal angulation of the central ray with the long axis of the body part.
4) Body movement: The following terms are used to describe movement related to the extremities:
a) Abduction and adduction
· Abduction :movement of a part away from central axis of body.
· Adduction : movement of a part toward central axis of body
b) Flexion and extension
· Extension :straightening of a joint; stretching of a part; also, a backward bending movement; opposite of flexion.
· Flexion : a bending movement of a joint whereby angle between contiguous bones is diminished; also , a forward bending movement; opposite of extension.
c) Inversion and eversion
· Evert or eversion: movement of the foot when turned outward at the ankle joint.
· Invert or inversion :movement of the foot when turned inward at the ankle joint.
d) Pronate and supinate
· Pronate: to turn arm so that palm of hand faces backward.
· Supinate: to turn arm so that palm of hand faces forward.
5) Central ray : refers to the direction of the X-ray beam arising from tube toward patient (area of interest):
a) Straight central ray: perpendicular , vertical or horizontal.
b) Angled central ray could be:
· Cephalad : the central ray is oriented superiorly /proximally.
· Caudad: the central ray is oriented inferiorly/distally or caudally.
· Medially: inside.
· Laterally: outside
· Anteriorly or posteriorly.
Chest - Lungs
1) PA Chest Projection :
a) Position:
- place the patient in the standing or sitting position, with arms hanging at sides.
- Place the hands low on the hips, with their palmars facing upward to rotate the scapulae laterally.
- Adjust the hight of cassette so that the upper border of the film is about 2 cm above the shoulders.
- The patient must keep the shoulders in contact with the grid device.
b) Central ray :
- Direct the central ray in the midsagittal plane to the central of the film at the level of the sixh thoracic vertebra.
c) Breating instructions:
- The radiography must be made at the end of full inhalation
d) Structures shown :
- The air-filled trachea.
- The lungs.
- The diaphragmatic domes.
- The heart and aortic knob.
- The bronchial tree is shown from an oblique angle.
e) Evaluation criteria :
- The sternal ends of the calvicles should be equidistant from the vertebral column.
- The trachea should be seen in the midline.
- The scapulae should be projected outside the lung fields .
- One to two inches of lung apex should show above the clavicles.
- Ten posterior ribs should be seen above the diaphragm .
- The distance from the vertebral column to the lateral border of the ribs should be equidistant on each side.
- A small amount of the heart should be seen on the right side of the vertebral column.
- The costophrenic angles must be included.
- The heart and diaphragm shoud show sharp outlines.
- A faint shadow of the ribs and superior thoracic vertebrae should be seen through the heart shadow.
- The exposure should clearly demonstrate the lungs fields.
2) Lateral chest projection :
a) Position :
- The left lateral (left side against the film):when the left lung is of primary interest.
- The right lateral : when the right lung is of primary interest.
- The upper border of the film must be 1 ½ inches above the shoulders.
- Have the patient sit or stand straight, extend the arms directly upward, flex the elbows, and , with the forearm resting on his head.
b) Central ray :
- Direct the central ray horizontally to the sixth thoracic vertebra.
c) Structures shown :
- The left lateral projection : is used to show the heart and aorta and left-sided pulmonary lesions :
- The right lateral projection : is used to show the right-sided pulmonary lesions :
- The lateral positions : are employed extensively to demonstrate the interlobar fissures, to differentiate the lobes, and to localise pulmonary lesions .
d) Evaluation criteria :
- The ribs posterior to the vertebral column should be superimposed .
- No shadow of the arm on its soft tissues overlapping the upper lung field.
- The long axis of the lung fields should be vertical , without forward-backward leaning.
- The sternum should be lateral and not rotated.
- The costo-phrenic angles and the apices of the lungs must be included.
- The exposure should penetrate the lung fields and heart,
- The thoracic intervertebral spaces should be open except for patients with scoliosis.
- The heart and diaphragm should show sharp outlines.
- The hilum should be in the approximate center of the radiography.
3) Chest: AP Projection :
a)Position :
- Patient is placed in the AP position, either erect or lying.
- If possible, flex the elbows, pronate the hands, and place the
hands on the hips to draw the scapulae laterally .
- Adjust the shoulders to lie in the same transverse plane.
- The exposure is made at the end of full inhalation.
a) Central ray :
Direct the central ray perpendicularly to the long axis of the sternum at the level of T7.
b) Structures shown :
- This position is used when the patient is too ill to be turned to
the prone position.
- Being farther from the film, the heart and great vessels cast
magnified shadows, and the lung fields appear shorter
because of the magnification of the shadow of the diaphragm .
- The shadows of the clavicles are projected higher, and the
ribs assume a more horizontal appearance.
c) Evaluation criteria :
- The medial portion of the clavicles should be equidistant from
the vertebral column.
- The trachea should be seen in the midline.
- The clavicles will lie more horizontal and obscure more the
apices than in PA projection .
- The distance from the vertebral column to the lateral border of
the ribs should be equidistant on each side.
- A small amount of the right ventricle should be seen on the
right side of the vertebral column.
- The costophrenic angles should be included.
- The exposure should demonstrate the lung fields clearly .
4) Chest : pulmonary apices :
A) PA axial pulmonary apices projection :
a) Position :
- Place the patient in the PA position, either standing or seated.
-Rest the chin on top of the grid device.
-Flex the elbows and place the hands, palms out, on the hips.
-Depress the shoulders, rotate the forward, and adjust hem to lie in the
same transverse plane.
-Have the patient keep the shoulders in contact with the grid device.
-Make the exposure at the end of full inhalation or full exhalation.
b) Central ray :
- If the exposure is made on inhalation: Direct the central ray through the third thoracic vertebra at an angle of 10 or 15 degrees cephalad.
- If the exposure is made on exhalation: Direct the central ray perpendicularly to the third thoracic vertebra.
c) Structures shown : -The apices project above the shadows of the clavicles.
d) Evaluation cirteria :
-The apices should be well demonstrated and included in their entirety.
-Along with the apices, only the adjacent upper lung region is shown.
-The calvicles should lie below the apices.
-The medial portion of the clavicles should be equidistant from the vertebral column
B) AP axial pulmonary apices projection :
a) Position :
- Place the patient in the AP projection , in the erect or the
supine position.
- Flex the elbows and place the hands on the hips with the
palms out, or pronate the hands beside the hips.
- Rotate the shoulders forward, and adjust them to lie in
the same transverse plane.
- Make the exposure at the end of full inhalation.
b) Central ray : Direct the central ray to the second thoracic vertebra at
an angle of 15 or 20 degrees cephalad.
c) Structures shown :
- This projection shows the apices lying below the
shadows of the clavicles.
d) Evaluation criteria :
- The calvicles should be lie superior to the apices.
- The sternal ends of the clavicles should be equidistant from the vertebral column.
- The apices should be included in their entirety.
- Only the apices and adjacent upper lung region need to be included on the radiography.
- The clavicles should be lying horizontally with their medial ends overlapping only the first or second ribs.
- The ribs should appear distorted with their anterior and posterior portions somewhat superimposed.
5) Chest : AP lordotic projections : LINDBLOM method:
a)Position:
I) AP lordotic projection :
- Place the patient in the AP position standing.
- Flex the elbows and place the hands , palms out, on the hips..
- Have the patient lean backward in a position of extreme lordosis and rest his shoulders against the vertical grid device .
- Make the exposure at the end of full inhalation.
II) Oblique lordotic projection :
a)position: Rotate the body approximately 30 degrees away from the AP position, with the affected side toward and centred to the grid.
b)Central ray : Direct the central ray horizontally to the midsternum .
c)Structures shown :-These both projections are used to demonstrate the
apices and such conditions as interlobar effusion .
d) Evaluation criteria :
1-AP axial lordotic :
- The clavicles should lie superior to the apices.
- The sternal ends of the clavicles should be equidistant from the vertebral column.
- The apices and lungs should be included in their entirety.
2- Oblique lordotic :
- The dependent apex and lung of the affected side should be demonstrated in its
entirety.
6) PA pulmonary apices lordotic projection : FLEISCHNER method:
a)Position :
- Place the patent in the PA position before a vertical grid device.
- Have the patient grasp the grid device, brace his abdomen against it, and then lean backward in a position of extreme lordosis.
- The thorax should be inclined posteriorly approximately 45 degrees .
- Make the exposure at the end of full inhalation.
b)Central ray :Direct the central ray horizontally to the fourth thoracic vertebra.
c)Structures shown:
- The magnified interlobar effusions should be demonstrated.
- The apices and lung should be shown.
d)Evaluation criteria :The same as for AP lordotic projection.
7) Lungs and pleura
I) Frontal projections ( AP or PA ) in lateral decubitus position :For fluid levels and small pneumothoraces :
a)Position :
- Patient placed in a lateral decubitus position, lying on either the right or the left, as indicated by the existing condition.
- Extend the arms well above the head.
-Place the anterior or posterior surface of the chest against a vertical
grid device.
-Make the exposure at the end of full inhalation.
a) Central ray : directed horizontally through the fourth or seventh vertebra.
b) Structures shown : The frontal projection ( AP or PA ) in lateral decubitus position reveals :
-The change in position of the fluid and reveals pulmonary areas
that are obscured by the fluid in standard projections.
-The presence of any free air in the case of a suspected
pneumothorax.
c) Evaluation criteria :
- The patient should not be rotated from a true frontal projection.
- The affected side should be included in its entirety.
- The apices should be shown.