Projectional radiography

Projectional radiography or plain film radiography is the practise of producing 2D X-ray images. Typically most body parts being x-rayed, have two 'projections' taken, usually at right angles to each other. This is for two reasons. First that many fractures are only visible in one plane, which exact plane is unknown to the radiographer until the images are taken. Secondly to assess alignment of fractures and spatial position of foreign bodies. Gathering as much information as possible is very important as it can mean the difference between a POP cast and surgery. Mammography and dental radiography also come under the category of projectional radiography, but these topics are too complex to include in this article.

Clinical applications of projectional radiography

Projectional radiography is typically used to detect:

Boney anomalies

*Fractures
*Dislocations
*Arthritis
*Benign and Malignant Tumours
*Scoliosis
*Other Bone Conditions i.e.Scleroderma and Osteomyelitis

Soft tissue anomalies

*Chest Pathology
*Acute Bowel Obstruction
*Bowel Perforations
*Foreign body

Divisions of the skeleton

The human skeleton is divided into two categories:
*Axial skeleton
*Appendicular skeleton

Axial skeleton

*Skull and Facial Bones
*Chest
*Cervical Spine
*Thoracic spine
*Lumbar spine
*Sacrum and Coccyx
*Abdomen

Appendicular skeleton

*Shoulder Girdle
*Humerus
*Elbow
*Radius and Ulna
*Wrist
*Hand
*Fingers / Thumb
*Pelvic girdle
*Femur
*Knee
*Tibia and Fibula
*Ankle
*Calcaneum
*Foot / Toes

Projectional radiography terminology

NOTE: The word 'view' is often used erroneously to describe a radiographic projection.

*AP - Antero-Posterior
*PA - Postero-Anterior
*Lateral - Projection taken with the central ray perpendicular to the midsaggital plane
*Oblique - Projection taken with the central ray at an angle to any of the body planes. Described by the angle of obliquity and the portion of the body the X-ray beam exits; right or left and posterior or anterior. For example a 45 degree Right Anterior Oblique of the Cevical Spine.
*Flexion - Joint is radiographed while in flexion
*Extension - Joint is radiographed while in extension
*Stress Views - Typically taken of joints held in a 'stressed' position. Test of stability.
*HBL, HCR or CTL - Horizontal Beam Lateral, Horizontal Central Ray, or Cross Table Lateral. Used to obtain a lateral projection usually when patients are unable to move.
*Prone - Patient lies on their front
*Supine - Patient lies on the back
*Decubitus - Patient laying down. Further described by the downside body surface: dorsal (backside down), ventral (frontside down), or lateral (left or right side down).
*OM - occipito-mental, an imaginary positioning line extending from the outer canthus of the eye to the external auditory meatus
*Cranial or Cephalad - Tube angulation towards the head
*Caudal - Tube angulation towards the feet

Equipment Used in Projectional Radiography

*Ceiling or Floor Mounted X-ray tube
*Height adjustable table
*Bucky or Digital Detector
*User Interface
*Image Receptor - Film / Screen Cassette or CR Plate / DR Detectors
*Processor or Image Reader
*Chest Stand

Differences around the world

Routine projections used in the UK

*Chest - "PA Only. Lateral on request by a Radiologist"
*Abdomen - "AP Only. Decubitus on special request"
*Cervical Spine - "AP and Lateral. Peg projection with trauma only. Obliques and Flexion and Extension on special request"
*Thoracic Spine - "AP and Lateral"
*Lumbar Spine - "AP and Lateral +/- L5/S1 view. Obliques and Flexion and Extension requests are rare"
*Pelvis - "AP only. SIJ projections (prone) on special request"
*Hip - "AP and Lateral"
*Skull - "None. Patient goes to CT."
*Sinus - "OM with open mouth"
*Facial Bones - "OM and OM 30°"
*Shoulder - "AP and Lateral Scapula or Axillary Projection. Other Special projections available on request"
*Clavicle - "AP and AP Cranial"
*Humerus - "AP and Lateral"
*Elbow - "AP and Lateral. Radial head projections available on request"
*Radius and Ulna - "AP and Lateral"
*Wrist - "AP and Lateral"
*Scaphoid - "AP with Ulna deviation, Lateral, Oblique and AP with 30° angulation"
*Hand - "AP and Oblique"
*Fingers / Thumb - "AP and Lateral"
*Femur - "AP and Lateral"
*Knee - "AP and Lateral. Intra Condular projections on request"
*Patella - "Skyline Projection"
*Tibia and Fibula - "AP and Lateral"
*Ankle - "AP/Mortice and Lateral"
*Calcaneum - "Axial and Lateral"
*Foot / Toes - "AP and Oblique"

Routine projections used in the US

Chest - (CXR) Includes a PA and Lateral with the patient standing or sitting up. Special projections include an AP in cases where the image needs to be obtained stat and with a portable device, particularly when a patient cannot be safely positioned upright. Lateral Decubitus may be used for visualization of air-fluid levels if an upright image cannot be obtained. AP Axial Lordotic projects the clavicles above the lung fields, allowing better visualization of the apices (which is extremely useful when looking for evidence of primary tuberculosis)

Abdomen - Usually a single AP supine (KUB—kidney, bladder, and ureter) projection. Special projections include a PA prone, Lateral Decubitus, upright AP, and Lateral Cross-Table (with the patient supine) A minimal acute obstructive series (for the purpose of ruling out small bowel obstruction) would include two views: typically, a supine view and an upright view (which would be sufficient to detect air-fluid levels), although a lateral decubitus could be substituted for the upright.

Cervical Spine - Five or six projections are common; a Lateral, two 45 degree obliques, an AP axial (Cephalad), an AP "Open Mouth" for C1-C2, and Cervicothoracic Lateral (Swimmer's) to better visualize C7-T1 if necessary. Special projections include a Lateral with Flexion and Extension of the cervical spine, an Axial for C1-C2 (Fuchs or Judd method), and an AP Axial (Caudad) for articular pillars.

Thoracic Spine - An AP and Lateral are basic projections. Obliques can be requested to visualize the intervertebral foramina.

Lumbar Spine - Basic projections include an AP, two Obliques, a Lateral, and a Lateral L5-S1 spot to better visualize the L5-S1 interspace. Special projections are AP Right and Left bending, and Laterals with Flexion and Extension.

Sacrum and Coccyx - If both bones are to be examined separate cephalad and caudad AP axial projections are obtained for the sacrum and coccyx respectively as well as a single Lateral of both bones.

Sternum - The two basic projections are a 15 to 20 degree Right Anterior Oblique and a Lateral.

Sternoclavicular Joints - Are usually ordered as a single PA and a Right and Left 15 degree Right Anterior Obliques.

Ribs - Common rib projections are based on the location of the area of interest. These are obtained with shorter wavelengths/higher frequencies/higher levels of radiation than a standard CXR.

*Anterior area of interest - a PA chest X-ray, a PA projection of the ribs, and a 45 degree Anterior Oblique with the non-interest side closest to the image receptor.

*Posterior area of interest - a PA chest X-ray, an AP projection of the ribs, and a 45 degree Posterior Oblique with the side of interest closest to the image receptor.

Routine projections used in Australia:

See also

*Radiography
*Medical imaging
*X-ray
*Radiologic technologist
*Computed radiography
*Digital radiography
*Tomography
*Anatomical terms of location

External links

* [http://www.rtstudents.com/radiology-positions.htm Online Radiography Positioning Manual]
* [http://www2.radiography.com/index.php Radiographers Forum Website - Discuss Imaging Projections]
* [http://www.nice.org.uk Nice Guidelines]
* [http://www.medical.philips.com/uk/ Philips Medical]
* [http://tosaweb.ncsd.k12.wy.us/faculty/lbell/Human%20Skeleton/human_skeleton_index.html.html The Human Skeleton]
* [http://www.shaderware.com/wiki_j/index.php?page=login RADIOGRAPHY WIKI] A fledgling radiography specific wiki [http://www.radme.com Radiology & Medical Imaging Web forums in Arabic]

References

*1.The Pocketbook of Radiographic Positioning by Ruth Sutherland
*2.Bones and Joints: A Guide for Students by Christine Gunn
*3.Imaging Atlas of Human Anatomy by Jamie Weir, Peter H. Abrahams
*4. [http://www.nice.org.uk Nice Guidelines]
*5. [http://tosaweb.ncsd.k12.wy.us/faculty/lbell/Human%20Skeleton/human_skeleton_index.html.html The Human Skeleton]
*6. [http://www.nyssrs.org] NY Society of Radiologic technologists