Author(s): Constantine Nicolozakes, MD, PhD, Crystal Graff, MD
Originally published: August 4, 2017 Last updated: April 2, 2026
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Overview and Description

Radiography is performed by transmitting ionizing electromagnetic radiation through bony structures and soft tissue, producing an image based on the absorption of X-ray photons. It is the most commonly used diagnostic imaging study. Radiography refers to multiple modalities: mammography and dual energy X-ray absorptiometry (DEXA) are examples of low energy projectional radiography, fluoroscopy and angiography are special applications used for real time imaging, computed tomography (CT) uses computed reconstruction to generate a cross-sectional image, and plain radiography (X-ray imaging) creates a single, static two-dimensional image. This article will focus on plain radiography, known colloquially as X-ray imaging.

Plain radiographs use a heterogeneous beam of X-rays projected toward a detector, creating an image based on the density and composition of the intervening objects. X-ray photons are the main source of ionizing electromagnetic radiation used in medical radiography. They are generated by bombarding an anode with high energy electrons emitted from a hot cathode. Detection methods include radiosensitive amplifying screens, image intensifiers, and digital detectors that reconstruct the image.1

Tissue density is reflected by the capacity to absorb X-rays. X-rays are unable to easily penetrate more dense tissue. The more dense a tissue is, the brighter and whiter it will appear on plain radiography.2 The following are listed in order of increasing radio-opacity, from darkest to brightest

  • Air (trachea, lungs, intestine, paranasal sinuses).
  • Fat.
  • Soft tissues (heart, kidney, muscles).
  • Water.
  • Calcium rich tissue (skeleton).
  • Enamel of the teeth.
  • Dense foreign bodies (metallic fillings), and radio-opaque contrast media (barium).

While there are few true contraindications, X-rays produce ionizing radiation as they deposit enough energy to eject an electron from an atom, potentially altering tissue at the molecular level. Ionizing radiation is carcinogenic, and cumulative exposure may increase the risk of cancer. Therefore, X-rays should be used judiciously in young children and pregnant women. Risk factors for tissue damage include radiation dose, younger age, female gender, and imaging radiosensitive regions (ex. ovaries/testes, lens, bone marrow, thyroid).3,4

Radiation at high doses can be harmful to tissues and is typically measured in milli-Sieverts (mSv). An X-ray of the spine is equivalent to 1.5 mSv, or 6 months of natural background radiation, whereas an extremity X-ray is 0.001 mSV, or 3 hours of natural background radiation. For reference, people living in Colorado receive an extra 1.5 mSv per year than sea level, and a coast-to-coast flight exposes travelers to roughly 0.03 mSv. It would take roughly 38 chest X-rays to equal the amount of normal background radiation one receives over the course of a year.3

Relevance to Clinical Practice

Specific features of clinical application

X-ray imaging is a relatively low cost, widely available, and highly utilized modality for the evaluation of various pathological states. It can assist the physiatrist in the diagnosis and evaluation of numerous conditions.

In general, plain radiography is used in the context of a thorough clinical history and physical examination to confirm a diagnosis, establish severity or progression of a disease, evaluate anatomic alignment, and enhance patient treatment. X-rays are also often required by insurance companies prior to pursuing advanced (MRI) imaging for joint-specific pathology.

Common applications include, but are not limited to

  • Diagnosis of fractures or joint dislocation
  • Demonstration of proper alignment and stabilization of bony fragments following fracture treatment
  • Guidance for interventional pain procedures and orthopedic/neurosurgical procedures, such as spine repair, spine fusion, joint replacement, and fracture reduction
  • Assessment for trauma, including skeletal injury or sequelae such as pneumothorax or aortic dissection
  • Evaluation of osteomyelitis
  • Diagnosis and evolution of pneumonia, atelectasis, pleural effusion, asthma, COPD, chronic bronchitis, bronchiolitis, and other pulmonary pathology
  • Evaluation of clinical cardiomegaly or heart failure
  • Evaluation of arthritis, abnormal bone growth, and bony changes seen in metabolic, inflammatory, or rheumatologic conditions
  • Evaluation of suspected bowel obstruction or perforation
  • Diagnosis and evaluation of scoliosis
  • Detection of primary or metastatic bone cancer
  • Evaluation of non-accidental injury, plagiocephaly, or craniosynostosis in children
  • Evaluation of growth plates and skeletal maturity
  • Location of foreign objects in soft tissues
  • Diagnosis of retropharyngeal abscess
  • Confirmation of device placement, such as a central line or a g-tube

X-ray films are oftentimes ordered in more than one projection to optimize visualization of anatomic structures and determine alignment. Commonly utilized views are anteroposterior (AP) and lateral, however there are other views that may be obtained depending on the clinical circumstances.

Specific diagnostic criteria that justify the use of radiography

Plain radiography is best utilized in the context of a patient-specific clinical history and physical examination, in relation to the chief complaint. Clinical decision-making rules have been developed in some specific situations (e.g., Ottawa Ankle Rule, Ottawa Knee Rule, Canadian C-Spine Rule and foot rules) to improve the diagnostic accuracy.5,6,7 The American College of Radiology also hosts the ACR Appropriateness Criteria® to guide clinicians on what imaging, including X-rays, is most suitable to order for different suspected pathology.

History

  • Onset
  • Location
  • Radiation of pain / pain referral pattern
  • Duration/Frequency
  • Severity
  • Quality, character, aggravating/alleviating factors
  • Neurological concerns
  • Associated symptoms

Physical examination

Radiographic examinations are most effective when performed in conjunction with a standard physical examination of the affected region, consisting of

  • Inspection
  • Palpation
  • Range of motion
  • Auscultation (if indicated)
  • Neurological examination
  • Special tests

Specific complications

There are few contraindications to plain radiography, though caution should be taken in young children and pregnant women, and providers need to weigh the risks and benefits of imaging. Cumulative radiation dosage should be monitored in the case of frequent imaging.

Functional assessment

The patient’s ability to tolerate the exam should always be considered prior to ordering.

Outcome prediction

Radiography can improve patient outcome by offering precise diagnostic and treatment localizations, often without significant delays or high costs seen with other imaging modalities.

Environmental effects

One advantage of plain radiography is that it can be conducted in the inpatient or outpatient setting, with portable application for patients who cannot undergo standing exams.

Translation into practice: Practice “pearls”/performance improvement in practice (PIPs)/changes in clinical practice behaviors and skills

While readily available, radiography should be used judiciously, as an extension of a thorough history and physical examination with an adequate pre-test probability.

Cutting Edge/Emerging and Unique Concepts and Practice

Radiography is a historically well-established modality, and most of the innovation in radiologic studies surrounds magnetic resonance imaging (MRI), CT scan, PET, fluoroscopy and ultrasound. However, recent advances in plain radiography include the evolution of computer-aided detection to artificial-intelligence (AI) assisted interpretation, digital mobile radiography, radiation dose reduction, and tomosynthesis.

Computer-aided detection arose in the 1980’s and utilized “task-specific” computer algorithms to detect abnormalities on imaging, most commonly to detect breast or pulmonary nodules.8 In more recent years, AI assisted interpretation has emerged as a high interest area of study to increase efficiency and accuracy of reading using it’s “task agnostic” method.8 Due to the high volume usage of plain radiography, particularly for chest x-rays and musculoskeletal ailments, it has proven to be quite efficacious in detecting pneumothoraxes, pleural effusions, tuberculosis, lines and tubes, fractures, and osteoarthritis. A meta-analysis in 2024 demonstrated that sensitivity and specificity of AI fracture detection both exceed 90% with performance better than in MRI or CT.9 AI was shown to increase sensitivity and positive predictive value of detecting COVID-19 changes on a chest X-ray.10 It is comparable to the level of performance of third-year radiology residents in reading chest X-rays,11 A European Society of Radiology survey in 2024 identified that 48% of radiologists utilize AI-based products or services in their clinical practice compared to 20% in 2018.12

There has also been an emerging usage of portable/mobile x-ray usage outside the hospital. Current common use settings include nursing homes, group homes, and homeless shelters.13,14 In theory, this method could increase efficiency and patient satisfaction without suffering a change in cost effectiveness or image quality.

As stated previously, the greatest hazard of repeated X-rays relates to radiation exposure. In a recent study, there was no difference in image quality of full spine images when comparing standard radiation doses to 50% standard dose.15

Some practitioners have been using breast tomosynthesis in lieu of mammography, where 10 X-rays are taken with 1/10th of the radiation dose per sequence, and the images are taken at different angles so the diagnostician can “scroll” through the tissue. This is thought to increase the sensitivity for detecting masses and further reduces radiation exposure compared to CT.16

More recently, tomosynthesis has been used for musculoskeletal applications, particularly in the detection of bone erosions in patients with established rheumatoid arthritis or in post-operative extremities. One study found that tomosynthesis had a higher sensitivity in detecting bone erosions, increased by 14% when compared to plain radiography, with an almost equivalent radiation burden.17 Tomosynthesis has also been shown to be a great middle ground between plain film x-ray and CT in detecting fractures, assessing bone healing and evaluating hardware placement.18

Gaps in Knowledge/Evidence Base

X-rays are historically limited in the evaluation of soft tissue and CT, MRI, or nuclear medicine studies are needed to confirm the diagnosis. However, advances in AI have narrowed this gap. In general, plain radiography is an extremely well-established modality, and it continues to be the most commonly used diagnostic imaging modality in medical practice.

References

  1. Michail C, Liaparinos P, Kalyvas N, Kandarakis I, Fountos G, Valais I. Radiation Detectors and Sensors in Medical Imaging. Sensors. 2024; 24(19):6251. https://doi.org/10.3390/s24196251
  2. Magee, D. J., Manske, R. C., “Orthopedic physical assessment. Principles and concepts” (2021).
  3. Health Risks from Exposure to Low Levels of Ionizing Radiation: BEIR VII Phase 2 |The National Academies Press. (n.d.). Retrieved August 23, 2022, from https://www.nap.edu/read/11340/chapter/1
  4. ICRP, 2007. The 2007 Recommendations of the International Commission on Radiological Protection. ICRP Publication 103. Ann. ICRP 37 (2-4).
  5. Stiell IG, Greenberg GH, McKnight RD, Nair RC, McDowell I, Worthington JR. A study to develop clinical decision rules for the use of radiography in acute ankle injuries. Ann Emerg Med. 1992 Apr;21(4):384-90. doi: 10.1016/s0196-0644(05)82656-3. PMID: 1554175.
  6. Stiell IG, Greenberg GH, Wells GA, McDowell I, Cwinn AA, Smith NA, Cacciotti TF, Sivilotti ML. Prospective validation of a decision rule for the use of radiography in acute knee injuries. JAMA. 1996 Feb 28;275(8):611-5. PMID: 8594242.
  7. Stiell IG, Wells GA, Vandemheen KL, Clement CM, Lesiuk H, De Maio VJ, Laupacis A, Schull M, McKnight RD, Verbeek R, Brison R, Cass D, Dreyer J, Eisenhauer MA, Greenberg GH, MacPhail I, Morrison L, Reardon M, Worthington J. The Canadian C-spine rule for radiography in alert and stable trauma patients. JAMA. 2001 Oct 17;286(15):1841-8. doi: 10.1001/jama.286.15.1841. PMID: 11597285.
  8. Oakden-Rayner L. The Rebirth of CAD: How Is Modern AI Different from the CAD We Know? Radiol Artif Intell. 2019 May 29;1(3):e180089. doi: 10.1148/ryai.2019180089. PMID: 33937793; PMCID: PMC8017402.
  9. Jung J, Dai J, Liu B, Wu Q. Artificial intelligence in fracture detection with different image modalities and data types: A systematic review and meta-analysis. PLOS Digit Health. 2024 Jan 30;3(1):e0000438. doi: 10.1371/journal.pdig.0000438. PMID: 38289965; PMCID: PMC10826962.
  10. Rangarajan, K., Muku, S., Garg, A.K. et al. Artificial Intelligence–assisted chest X-ray assessment scheme for COVID-19. Eur Radiol 31, 6039–6048 (2021). https://doi.org/10.1007/s00330-020-07628-5
  11. Wu JT, Wong KCL, Gur Y, et al. Comparison of Chest Radiograph Interpretations by Artificial Intelligence Algorithm vs Radiology Residents. JAMA Netw Open. 2020;3(10):e2022779. doi:10.1001/jamanetworkopen.2020.22779
  12. Zanardo M, Visser JJ, Colarieti A, Cuocolo R, Klontzas ME, Pinto Dos Santos D, Sardanelli F; European Society of Radiology (ESR). Impact of AI on radiology: a EuroAIM/EuSoMII 2024 survey among members of the European Society of Radiology. Insights Imaging. 2024 Oct 7;15(1):240. doi: 10.1186/s13244-024-01801-w. PMID: 39373853; PMCID: PMC11458846.
  13. Toppenberg, M.D., Christiansen, T.E.M., Rasmussen, F. et al. Mobile X-ray outside the hospital: a scoping review. BMC Health Serv Res 20, 767 (2020). https://doi.org/10.1186/s12913-020-05564-0
  14. Inacio MC, Jorissen RN, Gaget V, Tivey DR, Dollard J, Visvanathan R, Maddern GJ. Utilisation of mobile X-ray services by residents of long-term care facilities. Intern Med J. 2025 Jun;55(6):951-958. doi: 10.1111/imj.70034. Epub 2025 Mar 24. PMID: 40125877; PMCID: PMC12155079.
  15. Jeon MR, Park HJ, Lee SY, Kang KA, Kim EY, Hong HP, Youn I. Radiation dose reduction in plain radiography of the full-length lower extremity and full spine. Br J Radiol. 2017 Dec;90(1080):20170483. doi: 10.1259/bjr.20170483. Epub 2017 Oct 27. PMID: 28936890; PMCID: PMC6047650.
  16. ACR Statement on Breast Tomosynthesis. American College of Radiology | American College of Radiology. (2014, November 24). Retrieved August 23, 2022, from https://www.acr.org/About-Us/Media-Center/Position-Statements/Position-Statements-Folder/20141124-ACR-Statement-on-Breast-Tomosynthesis
  17. Simoni PA, Gerard LA, Kaiser MJ et al. Use of Tomosynthesis for Detection of Bone Erosions of the Foot in Patients With Established Rheumatoid Arthritis: Comparison With Radiography and CT. American Journal of Roentgenology. http://www.ajronline.org/doi/abs/10.2214/AJR.14.14120
  18. Blum A, Noël A, Regent D, Villani N, Gillet R, Gondim Teixeira P. Tomosynthesis in musculoskeletal pathology. Diagn Interv Imaging. 2018 Jul-Aug;99(7-8):423-441. doi: 10.1016/j.diii.2018.05.001. Epub 2018 May 30. PMID: 29859831.

Original Version of the Topic

Peter Torberntsson, MD, Dustin Anderson, MD. Plain Radiography, 8/4/2017

Previous Revision(s) of the Topic

Lindsay Burke, MD, Crystal Graff, MD, Dustin Anderson, MD. Plain Radiography. 4/20/20023

Author Disclosure

Constantine Nicolozakes, MD, PhD
Nothing to Disclose

Crystal Graff, MD
Nothing to Disclose