Conventional Radiography

By Dr. Amr A. Abd-Elghany

Mobile x-ray

Introduction• X-ray is an imaging technique that has been used since 1895

to show up abnormalities in bones and certain body tissue, such as breast tissue.

• X-rays are a type of high-energy radiation that is like light waves but higher in energy. An X-ray machine can produce short bursts of X-rays that pass easily through fluids and soft tissues of the body but are blocked by dense tissue such as bone.

• Contrast X-rays use a substance (called a contrast medium) that makes hollow or fluid-filled structures visible. This means that structures such as the digestive tract, blood vessels or urinary system that do not usually show up on X-ray, can be seen. The substance is injected or swallowed and X-rays cannot pass through it, so the area will appear white on the X-ray.

What are x-rays?

No mass No charge Energy

What is yourobservation?

Basic x-ray physics

• X-rays: a form of electromagnetic energy• Travel at the speed of light• Electromagnetic spectrum– Gamma Rays X-rays– Visible light Infrared light–Microwaves Radar– Radio waves

Three things can happen

• X-rays can:– Pass all the way through the body– Be deflected or scattered– Be absorbed

Where on this imagehave x-rays passedthrough the bodyto the greatest degree?

X-rays Passing Through Tissue • Depends on the energy of the x-ray and the

atomic number of the tissue• Higher energy x-ray - more likely to pass

through• Higher atomic number - more likely to absorb

the x-ray

Diagnosis?

How do x-rays passing through the body create an image?

• X-rays that pass through the body to the film render the film dark (black)

• X-rays that are totally blocked do not reach the film and render the film light (white)

• Air = low atomic # = x-rays get through = image is dark

• Metal = high atomic # = x-rays blocked = image is light (white)

5 Basic Radiographic Densities

• Air• Fat• Soft tissue/fluid• Mineral• Metal

1.

2.

3.

4.

5.

Name these radiographic densities.

History: “I think my dog swallowed a rock”

Diagnosis: “Yes, he did.”

• What is used for?• Check bone fractures and osteoporosis.• Check teeth and joints.• Examine heart and lungs (chest x-ray).• Examine breast tumors (mammogram).

Chest Radiographs• Advantages (frequency 40%)• Simple• Low cost• Sensitive• Excellent resolution.

Steps for optimal chest x-ray

• Accurate patient positioning• Tube film distance• Full inspiration

• Adequate penetration (thin patient takes low dose while fat one takes higher dose for good image resolution)

Exposure (technique) factors for film screen imaging

• Kilovolt (kV)-controls the energy (penetrating power) of the x-ray beam.

• Milliamperage (mA)-controls the quantity or number of x-rays produced.

• Exposure time (ms)-controls the duration of the exposure, usually expressed in milliseconds.

General Terms

• Radiograph: is a film or other base material containing a processed image of an anatomic part of the patient as produced by action of x-rays on an IR.

• Radiography: the production of radiographs or other forms of radiographic images.

• Radiograph vs. x-ray film: x-ray film refers the physical piece of material on which a radiographic image is exposed. The term radiograph includes the film and the image.

• Radiographic images: are representation of patient anatomic structures. They can be obtained as a hard copy or digitally.

Radiographic examination or procedure

• Positioning of the body part and central ray CR.

• Selection of the radiation protection measures.• Selection of the exposure factors on the

control panel.• Patient instructions relating to respiration .• Processing of the IR.

Positioning • Postro-anterior (Chest PA): -The radiation enters the body from the posterior. -Standard position preferred in diagnosis. -The heart is near to the film so there is no

magnification of the heart.- Lung divided into four regions:- Apex- Upper lung zone- Middle lung zone- Lower lung zone

• Antero posterior chest X-ray

• In case of emergency patients (Supine AP).

PA versus AP• The AP shows magnification of the heart (transverse

cardiac diameter not correct) and mediastinum.• AP views are less useful and should be reserved for

very ill patients who cannot stand erect.

Erect versus supine chest x-ray

• False impression due to magnified heart and difficulty in breathing (wrong diaphragm position).

Left lateral• To detect lesions (is any abnormality in the tissue of

an organism) in the left lung.• The left side is near from the film.

Adequate penetration

Over exposureOver dose

under exposureWe can not see details

Full inspiration level

• The diaphragm is at the 10th rib in the full inspiration level.

Lateral chest x-ray

• Lower dorsal vertebrae are darker than upper ones due to the presence of shoulder bones (normal).

• If the upper dorsal vertebrae were dark and lower ones were brighter then we have lesions may be pneumonia.

Right lower lobe

Normal PA film without rotation

Di

Diagnosis?

Radiographic Analysis

• Any structure, normal or pathologic, should be analyzed for:

1. Size2. Shape and contour3. Position4. Density (You must know the 5 basic

densities)

Radiographic signs

• Silhouette sign: opacity near the heart so you can not detect the heart boarder easily.

• Notes from the radiographs: opacity frontal and heart frontal so lesion is frontal.