Background

Chest radiography is the most frequently utilized diagnostic imaging procedure. In fact, the World Health Organization estimated that half of all radiologic procedures performed worldwide are chest x-rays (CXRs) (1).

Use of Routine CXRs

Ordering chest x-rays on patients without cardiopulmonary disease has not been shown to improve patient outcome and is not cost-effective, due to the low prevalence of cardiopulmonary diseases in the general population (2). In fact, routine chest radiography may lead to false positive results and exposes patients to unnecessary radiation. The use of chest x-rays in inpatient, outpatient, preoperative or pre-anesthesia settings should be based on clinical parameters.

General Guidelines

Chest radiography should be ordered and interpreted in the context of a complete medical history and physical exam. The physician should inquire about occupational and environmental exposures, allergies and pertinent systemic diseases (e.g., GE reflux, COPD, congestive heart failure) and search for signs and symptoms of respiratory or cardiac disease. Unless the results will impact patient management, a CXR is not indicated (3).

According to the American College of Radiology, some indications for chest radiography Include (4):

• Signs and symptoms potentially related to the respiratory, cardiovascular, or upper gastrointestinal systems, or the musculoskeletal system of the thorax.
• Follow-up of known thoracic disease.
• Compliance with government regulations (e.g., immigration chest films).

Screening CXR

Screening patients at high risk for lung cancer (e.g., smokers) has not been found to lead to a reduction in cancer mortality and is not considered beneficial (5).

There is no clear indication for obtaining a pre-employment screening CXR to look for tuberculosis (6). PPD is the most widely used and effective test to screen for tuberculosis (7).

Cough

CXR is not always indicated in the initial workup of cough (8). Unless the patient smokes, is immuno-compromised, or has symptoms such as hemoptysis, fever, weight loss or dyspnea, a chest x-ray is usually not indicated following the first visit. Instead, one might consider evaluating and/or treating the patient empirically first for chronic rhinitis, GERD or asthma (8). If there is no response to treatment, then imaging studies may be indicated.

Pneumonia

Healthy, young, nonsmoking patients with community acquired pneumonia whose symptoms fully resolve following therapy generally do not need follow-up CXR (3). In patients who fail to respond to therapy, CXR, sputum gram stain and culture and additional workup may be indicated.

Follow-up CXR should not generally be done until at least 4 to 6 weeks out, on patients with uncomplicated pneumonia and good clinical resolution. Follow-up CXRs performed too soon on such patients are a common cause for film misinterpretation because abnormalities on CXR attributable to pneumonia may remain for 4-6 weeks after the patient has been treated and clinical symptoms resolve (3).

There are several indications for follow-up CXR (Table I):

Table I

Follow-up CXR indications

Elderly patients

Smoking history

Immunosuppression

More virulent pathogen (e.g., gram negative)

Underlying chronic disease

Persistent symptoms > 8 weeks

Initial unusual x-ray findings

Patients at a higher risk for complications related to pneumonia may warrant a CXR at initial presentation (3) (Table II):

Table II

High Risk For Complicated Pneumonia

Infants, young children and the elderly

Underlying chronic disease

Impaired mental status

Impaired swallowing mechanism

Immunosuppression (including AIDS)

Chronic corticosteroid therapy

Alcoholism or drug abuse

CXRs in the Elderly

Chest x-rays are not indicated solely in response to a patient's advanced age (9). Although the elderly are more likely to have medical conditions associated with chest pathology, under normal situations the elderly only need chest imaging when they present with signs or symptoms of significant chest disease.

Preadmission, Pre- and Postoperative CXRs

Chest x-rays are not indicated routinely as part of hospital admission, preoperative, pre-anesthesia or postoperative assessment (9). Unless active disease is suspected on history or physical exam, chest x-rays rarely impact patient outcome (2). In fact, only 1.3% of routine preoperative chest films showed an unexpected abnormality, and only 0.1% ultimately impacted patient management (11).

According to Barnard, there are four indications for a preoperative chest radiograph (10):

1. Cardiopulmonary disease - (if no chest x-rays done within the past year)
2. Possible primary or secondary malignancy
3. Severe trauma
4. Immigrants from countries with endemic TB - (if no chest x-rays done within the past year)
   

In addition, chest x-rays may be indicated preoperatively in patients scheduled to undergo surgery involving the thorax (9). According to the American College of Radiology standard (4):

• Preoperative radiographic evaluation is indicated if cardiac or respiratory symptoms are present or if there is a significant potential for thoracic pathology that may compromise the surgical result or lead to increased preoperative morbidity or mortality.
• Chest radiographs are appropriate for monitoring patients with life-support devices and patients who have undergone cardiac or thoracic surgery or other interventional procedures.

Conclusion

In conclusion, chest radiography is indicated only when there is a clinical suspicion of chest disease based on findings on a prior medical history and physical examination.

References

1. WHO Scientific Group on the Indications for and Limitations of Major X-ray Diagnostic Investigations. A rational approach to radiodiagnostic investigations. Geneve. Switzerland: World Health Organization; 1983:7-28. (WHO Technical Report Series No. 689). 
2. Tape TG, Mushlin AI. The Utility of Routine Chest Radiographs. In Sox HC (ed):Common Diagnostic Tests: Use and Interpretation. Philadelphia, American College of Physicians, 1990, p. 79-99.
3. Curtis AB, Putmen CE, Wrenn, KD. Pneumonia: reading chest films right. Patient care 1992;December 5:40-71.
4. ACR Standard for the Performance of Pediatric and Adult Chest Radiography. American College of Radiology, 1997.ACR Publications, Reston, VA 22901.
5. Brawley OW, Kramer BS: Chapter 82. Prevention and early detection of cancer. In Fauci S, Braunwald E, Isselbacher KJ et al (eds): Harrisons Principles of Internal Medicine. New York, McGraw-Hill, 1998, pp.499-505. 
6. Briggs GM. Chest imaging: indications and interpretation. Med. J. Aust. 1997;166:555-560. 
7. Raviglione AC, O'Brien RJ: Chapter 171. Tuberculosis. In Fauci S, Braunwald E, Isselbacher KJ et al (eds): Harrisons Principles of Internal Medicine. New York,McGraw-Hill, 1998, pp.1004-1014.
8. Pratter MR, et al. An algorithmic approach to chronic cough. Annals of Internal Medicine 1993;119(10):977-83
9. Peters DS: Introduction to the Blue Cross Blue Shield Association guidelines. In Sox HC (ed):Common Diagnostic Tests: Use and Interpretation, Philadelphia, American College of Physicians, 1990, p. 398.
10. Barnard NA, Williams RW, Spencer EM. Preoperative patient assessment: a review of the literature and recommendations. Ann RColl Surg Engl 1994;76:293-297.
11. Archer C, Levy AR, McGregor M. Value of routine preoperative chest X-rays: a meta-analysis. Can J Anasth 1993;40(11): 1022-1027.

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