Radiology Technical workers administer different forms of radiation to produce images for diagnostic purposes of the human body. Although often overlooked, the way radiation is produced, administered, and used in medical procedures is different depending on the type of radiation and images need for healthcare services.
For example, X-rays and gamma rays are both forms of ionizing radiation, meaning they have enough energy to remove electrons from atoms and potentially damage DNA. The major distinction is that X-ray procedures use an external machine to produce and direct radiation through the patient, while gamma-ray procedures generally use radioactive material that emits radiation from within or around the patient.
This is one of many differences that radiology technicians must always be aware of when producing images and administering radiation.
The following information explores these differences in more detail and explains their importance:
During a conventional X-ray, the patient is positioned between an X-ray tube and a detector. The X-ray machine produces a beam that passes through the body. The procedure is usually relatively quick and involves one or several exposures of a particular body part. Examples include chest, abdominal, dental, and extremity X-rays.
Different tissues absorb different amounts of radiation, and the remaining radiation reaches the detector to create the image. This requires changing the amount radiation which appropriate in relationship to the targeted area. Dense structures such as bone absorb more X-rays and therefore appear lighter on the image.
The amount of radiation depends on the examination. For example, the EPA lists an approximate dose of 0.02 mSv for a single chest X-ray, while an abdominal X-ray is approximately 0.7 mSv.
A CT scan also uses X-rays, but the procedure is more complex than a conventional X-ray. Instead of producing one image, the X-ray tube and detectors rotate around the patient and collect many X-ray projections. A computer then reconstructs these measurements into cross-sectional “slices” and sometimes 3-D images.
Because many X-ray projections are used, CT generally exposes the patient to more radiation than a conventional X-ray. The EPA gives approximate doses of 2.0 mSv for a head CT, 8.0 mSv for a chest CT, and 10 mSv for an abdominal or pelvic CT.
Fluoroscopy is more complex compared to a regular X-ray because it provides real-time X-ray imaging. Rather than taking a single still image, X-rays are transmitted through the body while the images are displayed on a monitor. This allows physicians to watch movement or guide instruments such as catheters.
For example, fluoroscopy may be used during angiography, angioplasty, orthopedic procedures, or gastrointestinal studies involving contrast material.
Because fluoroscopy can involve prolonged radiation exposure, it can result in higher doses than conventional radiography, particularly during lengthy interventional procedures.
Gamma-ray procedures are administered differently from conventional X-rays. Instead of having an X-ray machine send radiation into the patient, nuclear medicine uses a radioactive tracer that is introduced into the patient’s body. The tracer may be injected, swallowed, or inhaled. The radioactive material travels to specific organs or tissues and emits radiation that can be detected by specialized imaging equipment.
This means nuclear medicine is particularly useful for examining function rather than just anatomy. For example, an X-ray can show the structure of a bone, while a nuclear medicine study can show how certain tissues or organs are functioning.
This is an important procedural difference:
Ionizing radiation is also used for treatment, not just diagnosis. Radiation therapy uses high doses of radiation to damage or destroy diseased cells, particularly cancer cells. Unlike a diagnostic X-ray, where the goal is to obtain an image using the lowest reasonable dose, radiation therapy intentionally delivers a much larger dose to a specific treatment area.
Nuclear medicine can also have therapeutic applications when radioactive material is designed to target particular diseased tissues. The CDC notes that nuclear medicine can be also used for diagnosis and to target and destroy damaged or diseased tissue.
Although the procedures differ when administrating radiation for a treatment, a common principle outlined by multiple medical and nuclear organizations is ALARA — “as low as reasonably achievable.” For diagnostic procedures such as X-rays, CT, and fluoroscopy, healthcare professionals attempt to use the lowest amount of radiation necessary to obtain adequate diagnostic information.
The FDA also emphasizes justification and optimization: the examination should be medically justified, and the radiation exposure should be optimized for the specific patient and examination.
Special attention is given to children and pregnant patients because developing tissues are more sensitive to radiation. Patients should tell their healthcare provider if they are pregnant or might be pregnant so the examination can be evaluated or modified when appropriate.
The main difference is where the radiation comes from. X-rays are produced by an external X-ray machine and directed through the patient’s body. Gamma rays used in nuclear medicine generally come from radioactive material, or a tracer, that is introduced into the patient’s body.
No. The procedure depends on the purpose and type of radiation being used. X-rays, CT, and fluoroscopy use an external X-ray source, nuclear medicine uses radioactive material introduced into the body, and radiation therapy uses high doses of radiation to treat disease.
Pregnancy can require additional consideration when an examination involves ionizing radiation because developing tissues can be more sensitive to radiation. Informing the healthcare provider allows the procedure to be evaluated and, when appropriate, modified to protect the patient and developing fetus while still addressing the medical need.
Children are more sensitive to radiation because their bodies are still developing. Healthcare professionals therefore pay particular attention to using appropriate radiation settings and avoiding unnecessary exposure while still obtaining the information needed for diagnosis.
Diagnostic imaging uses radiation to obtain information about the body’s structure or function, while radiation therapy uses much higher doses of radiation to damage or destroy diseased cells, particularly cancer cells. The goal of diagnostic imaging is to obtain useful medical information while minimizing exposure, whereas radiation therapy intentionally delivers a therapeutic dose to a targeted area.
The biggest difference is where the radiation comes from and what the procedure is trying to accomplish. X-rays, CT, and fluoroscopy use an external X-ray source, with CT collecting many projections and fluoroscopy providing real-time images. Gamma-ray/nuclear medicine procedures put a radioactive tracer inside the patient, allowing a camera to detect radiation and show organ function. Finally, radiation therapy uses ionizing radiation at much higher therapeutic doses to destroy diseased tissue rather than create a diagnostic image. Regardless of the modality, healthcare professionals must balance the medical benefit against radiation risk and use radiation as efficiently and safely as possible. In order to do this, having a complete understanding of the different procedures when producing with radiation.
Radiography combines medical imaging technology, patient care, positioning, and radiation-safety principles to produce diagnostic images used by healthcare professionals.
Midwestern Career College’s AAS in Diagnostic Medical Imaging Radiography prepares students for entry-level roles in radiography while developing foundational knowledge and skills in imaging procedures, patient care, radiation protection, and clinical practice.
This article was developed using guidance and educational resources from the following medical and clinical organizations:
Arthur Bagdasaryan is Content Creation & Editorial Specialist at Midwestern Career College. He develops informative, accessible content designed to help readers better understand career-focused education, healthcare topics, and the professional landscape.
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