A conventional X-ray produces a 2D image, so it cannot show depth and organs may overlap on the image. CT (Computed Tomography) creates 3D images and cross-sectional slices, which helps doctors evaluate internal abnormalities more clearly.
CT scans usually involve higher radiation exposure than conventional X-rays. For patient benefit, doctors typically order a conventional X-ray first, and use CT scanning when the X-ray result is not clear enough for diagnosis.
Benefits of X-ray Imaging
X-ray imaging helps examine tissues and organs across many body areas and supports accurate diagnosis and effective treatment.
Common X-ray examinations include:
- Chest X-ray (lungs, heart, rib cage)
- Bone and dental X-ray (fractures, tumors, tooth decay)
Safety and Radiation Risk
X-rays are a type of radiation and may cause cellular damage, depending on the dose and the sensitivity of the cells exposed. Pregnant women should avoid X-rays unless medically necessary, because fetal cells are more sensitive and exposure may increase the risk of miscarriage or birth abnormalities.
Long-term exposure may increase health risks through DNA changes (mutations), which can contribute to conditions such as leukemia or cancer. For this reason, X-rays are considered a carcinogen, and doctors recommend them only when there is a clear clinical indication. Overall, the cancer risk from medical X-rays is considered very low, and the benefit of diagnosis typically outweighs the risk.
When Do Doctors Order an X-ray?
Doctors commonly order X-rays for:
- Chest symptoms (e.g., abnormal breath sounds)
- Suspected bone fractures after injuries or accidents
X-rays may also be used for health screening when medically appropriate, such as an annual chest X-ray for adults around 20–25 years and above.
CT scans are used in more specific cases, especially when doctors need clearer results for complex conditions or internal organ abnormalities.
Special Digestive System X-rays
For digestive examinations, doctors may use contrast studies such as:
- Barium swallow / Upper GI series (esophagus, stomach, small intestine)
- Barium enema (large intestine)
In some cases, doctors may choose abdominal CT for more detailed results.
Preparation and After the Exam
Conventional X-rays usually require minimal preparation and typically take about 10 minutes, while exposure lasts only 1–2 seconds. Patients can return to normal activities immediately.
For barium studies, contrast material may be cleared through bowel movements within 2–3 days.
Before the exam, patients should remove metal objects and avoid clothing with metal parts, as metal can affect image accuracy. Medical staff may ask about menstruation history to help prevent unintended X-ray exposure during pregnancy.
Results and Record Keeping
Conventional X-ray results are often available the same day, while CT results may take longer and are reviewed by radiologists. Results may be provided as film, CD/DVD, or digital files. Patients should keep imaging records to help doctors compare findings over time.
Limitations
Imaging may have limitations, with an interpretation error rate reported around 10–15% in some cases. Doctors therefore combine imaging with symptoms, physical examination, laboratory results, and other investigations when needed. Frequent exposure to ionizing radiation may carry long-term risks, so X-rays should be performed only when medically necessary.
References
- Hall, E. (1994). Radiobiology for Radiologists. Philadelphia: J.B. Lippincott Company.
- Radiation Protection. ICRP Publication 60. Office of Atoms for Peace (Thailand), 1994.
- X-ray. http://en.wikipedia.org/wiki/X-ray (accessed Nov 5, 2016)
- S. NRC. Radiation Health Effects. http://www.nrc.gov/about-nrc/radiation/rad-health-effects.html (accessed Nov 5, 2016)
- Radiation Protection of Patients (RPoP). https://rpop.iaea.org/RPoP/RPoP/Content/index.html (accessed Nov 5, 2016)
U.S. NRC. CFR Part 20. http://www.nrc.gov/reading-rm/doc-collections/cfr/part020/ (accessed Nov 5, 2016)
