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  • Print publication year: 2015
  • Online publication date: July 2015

44 - Principles of plain film

from Section 11 - Surgical radiology


Plain film consists of a single shot image using x rays.

What are the different densities in x rays?

• Black – gas

• White – calcified structures

• Grey – soft tissues

• Darker grey – fat

• Intense white – metallic objects

What are the basics that must not be missed?

Always check:

• Name of patient, date of birth and date – this may give information about patient's age and gender, which could elucidate the underlying pathology.

• Adequacy of imaging: does the x ray cover the entire area of interest?

• Orientation of film: right vs. left – ‘R’ label on corner of film.

• Position of patient. For example, a pneumothorax will look different on supine chest x ray vs. erect film; air under the diaphragm will not be seen in a chest x ray of a patient lying flat.

• Cervical spine: multiple standardised views (see Chapter 49, Cervical spine x ray).

• Distal limbs: minimum of two views. If only one view is shown, ask for a second view.

What are the rules of 2?

• 2 sides: in paired structures (e.g. limbs) always compare the affected structure with the contralateral one, which may be normal.

• 2 views: obtain two views of the same structure, e.g. anteroposterior and lateral.

• 2 times: view images of the same structure at two different points in time: compare current images with previous ones.

• 2 joints (in orthopaedics): view the joint above and the joint below the one of interest.

• 2 readers: get a second opinion.

What is fluoroscopy?

• An imaging modality that uses continuous x ray exposure to get dynamic imaging

• Has the capacity to save representative images

• Contrast material used to help differentiate pathology.