Medical Uses and Techniques
- Radiography is used for diagnostic purposes and to guide therapeutic interventions.
- Different modalities of medical radiography have different clinical applications.
- Computed tomography (CT) uses ionizing radiation and a computer to create detailed images of soft and hard tissues.
- Dual energy X-ray absorptiometry (DEXA) is primarily used for osteoporosis tests.
- Fluoroscopy provides moving projection radiographs and is used to view tissue movement or guide medical interventions.
Industrial Radiography
- Industrial radiography is a method of non-destructive testing used to examine the internal structure and integrity of manufactured components.
- It utilizes X-rays or gamma rays, which have the ability to penetrate and travel through materials.
- Industrial computed tomography is a specific method used in industrial radiography.
Image Quality and Radiation Dose
- Image quality in radiography depends on resolution and density.
- The resolution is the ability to show closely spaced structures as separate entities.
- The density is the blackening power of the image.
- The radiation dose varies by procedure, with chest X-rays having an effective dosage of 0.1mSv and abdominal CT scans having an effective dosage of 10mSv.
- Safety standards are in place to ensure low radiation dosage.
Shielding and Campaigns
- Lead is the most common shield against X-rays due to its high density and stopping power.
- The thickness of lead shielding depends on X-ray energy, and shielding is exponential.
- The Image Gently campaign promotes low radiation doses and best safety practices in paediatric imaging, while the Image Wisely campaign addresses radiation dose in the adult population.
- The World Health Organization and International Atomic Energy Agency work to lower patient radiation dose, and professional medical organizations and equipment manufacturers support these campaigns.
Equipment and History
- X-ray generators, X-ray tubes, and other sources of X-ray photons are used in radiography.
- Various detectors are used for imaging and dose measurement.
- Radiography and fluoroscopy originated from Wilhelm Conrad Röntgen's discovery of X-rays in 1895.
- Radiography was used to treat wounded soldiers in World War I, advocated by Marie Curie.
- The early history of X-rays is documented in various publications, and the Nobel Prizes in Physics recognised their importance.
Radiography is an imaging technique using X-rays, gamma rays, or similar ionizing radiation and non-ionizing radiation to view the internal form of an object. Applications of radiography include medical ("diagnostic" radiography and "therapeutic") and industrial radiography. Similar techniques are used in airport security, (where "body scanners" generally use backscatter X-ray). To create an image in conventional radiography, a beam of X-rays is produced by an X-ray generator and it is projected towards the object. A certain amount of the X-rays or other radiation are absorbed by the object, dependent on the object's density and structural composition. The X-rays that pass through the object are captured behind the object by a detector (either photographic film or a digital detector). The generation of flat two-dimensional images by this technique is called projectional radiography. In computed tomography (CT scanning), an X-ray source and its associated detectors rotate around the subject, which itself moves through the conical X-ray beam produced. Any given point within the subject is crossed from many directions by many different beams at different times. Information regarding the attenuation of these beams is collated and subjected to computation to generate two-dimensional images on three planes (axial, coronal, and sagittal) which can be further processed to produce a three-dimensional image.
 Projectional radiography of the knee in a modern X-ray machine | |
| System | Musculoskeletal |
|---|---|
| Subdivisions | Interventional, Nuclear, Therapeutic, Paediatric |
| Significant diseases | Cancer, bone fractures |
| Significant tests | screening tests, X-ray, CT, MRI, PET, bone scan, ultrasonography, mammography, fluoroscopy |
| Specialist | Radiographer |
radio- + -graphy
radiography (uncountable)
