What Nurses Need to Know About CT Scans

Computed tomography (CT), also known as a computed axial tomography (CAT) scan, is a diagnostic tool in modern healthcare. Nurses frequently help prepare, educate, and support patients undergoing CT imaging.  

This article provides a comprehensive overview tailored to nursing practice, emphasizing the importance of clinical vigilance and patient-centered care. 

What is a CT scan? 

A CT scan, which stands for computed tomography, combines X-ray images taken from various angles with computer processing to produce comprehensive cross-sectional views of bones, blood vessels, and soft tissues.  

In 1972, Sir Godfrey Hounsfield, an electrical engineer, invented the first version of a CT scanner, and at the same time, Dr. Allan McLeod Cormack created a similar tool. The CT scan revolutionized diagnostic imaging by enabling clinicians to visualize internal structures with unprecedented clarity.  

These high-resolution images allow clinicians to detect a wide range of abnormalities, including tumors, hemorrhages, bone fractures, vascular malformations, and internal organ pathology, with greater precision than standard X-rays. The imaging is particularly useful in assessing complex anatomical structures, guiding interventional procedures, and monitoring disease progression or response to therapy. 

How does a CT scan work? 

During a CT scan, an X-ray tube spins around the patient, capturing multiple images in thin slices. A computer then recreates these slices into a 3D image for diagnostic interpretation.  

The scanner's gantry and computer software synchronize to provide rapid, detailed visualization of internal organs and tissues. Depending on the scan's purpose, contrast agents may be administered orally, intravenously, or rectally to enhance image clarity. 

Step-by-step, a CT scan typically works as follows: 

• The patient is positioned on a motorized table that slides into the CT scanner. 
• The radiologic technologist ensures the patient is correctly aligned and provides instructions to remain still. 
• The X-ray tube within the scanner rotates around the patient, emitting X-rays through the body from various angles. 
• Detectors opposite the X-ray source capture the X-rays that pass through the body. 
• These data are transmitted to a computer which reconstructs the captured images into detailed cross-sectional slices. 
• If contrast media is used, it may be administered before or during scanning to highlight specific tissues or blood vessels. 
• The series of images is compiled into a 3D representation for radiologist interpretation. 
• The technologist reviews image quality before completing the session and assisting the patient off the table. 

How long does a CT scan take? 

The duration varies by body region and whether contrast is used. Most scans take 10 to 30 minutes, although preparation and post-scan monitoring may extend the overall process.  

For example, obtaining venous access, administering contrast media, or accommodating mobility limitations may increase total time spent with the patient. 

What does a CT scan show nurses? 

CT scans provide nurses with critical information about internal injuries, tumors, infections, vascular conditions, and more. Understanding scan results helps nurses anticipate patient needs, monitor for complications, and communicate effectively with the care team. This knowledge also enables nurses to advocate for timely interventions and clarify clinical priorities. 

What can a CT scan detect? 

Common indications for CT imaging include: 

• Trauma (e.g., head injuries, internal bleeding) 
• Suspected stroke or pulmonary embolism 
• Tumor identification and staging 
• Bone fractures 
• Abdominal and pelvic pain evaluation 
• Infection localization (e.g., abscesses) CT imaging can also assist in procedural planning, such as biopsies or surgical interventions, by delineating anatomical landmarks with precision. 

How long do CT scan results take? 

Preliminary results may be available within hours, especially in emergency settings. Final radiology reports typically take 24 to 48 hours.  

Nurses should manage patient expectations and provide follow-up guidance. In cases of urgent findings, radiologists may directly alert the clinical team to expedite care. 

Does a CT scan use radiation? 

CT scans use ionizing radiation, which carries a low but measurable risk of tissue damage and carcinogenesis over time. The radiation dose depends on multiple factors, including the scan type, area of the body being imaged, patient size, and whether contrast is used.  

For example, a head CT typically delivers a dose of approximately 2 mSv (millisieverts), while an abdominal CT may exceed 10 mSv. While the radiation doesn’t remain in the body, repeated exposure can accumulate risk, especially in younger or more radiosensitive patients. 

Nurses play a critical role in patient education by explaining that: 

• The advantages of correct diagnosis often outweigh the small radiation risk. 
• Radiation exposure from CT scans is generally low and carefully controlled. 
• Alternative imaging methods (e.g., MRI or ultrasound) may be considered when clinically appropriate. 
• Protective measures, such as shielding and limiting scan frequency, are routinely used. 

It’s important to reassure patients while providing accurate information. Patients should be encouraged to keep a record of their imaging history and inform providers of any previous scans, especially if imaging is frequent or involves multiple body areas. 

What should patients avoid eating or drinking before a CT scan? 

Fasting guidelines vary: 

• For contrast-enhanced scans, patients are typically advised to avoid food and drink for two to six hours before the exam. 
• For non-contrast scans, restrictions may be minimal or none. Nurses should verify and reinforce facility-specific protocols. Ensuring patient compliance with pre-scan instructions improves image quality and minimizes the risk of complications, such as aspiration or contrast intolerance. 

The nurse's role in CT scanning 

Nurses contribute significantly to CT imaging workflows, including: 

• Educating patients about the procedure and addressing concerns 
• Assessing for allergies to contrast media (e.g., iodine) 
• Monitoring vital signs before and after contrast administration 
• Ensuring pre-scan preparation (e.g., IV access, NPO status) 
• Transporting and positioning patients safely 
• Communicating abnormal findings or patient reactions to the healthcare team Additionally, nurses play a key role in patient advocacy, helping patients feel comfortable and informed throughout the diagnostic process. 

Everything nurses need to know about CT scans 

In addition to the roles outlined above, nurses should understand the following when involved in CT scan procedures: 

• Documentation: Record contrast use, patient allergies, pre-scan preparations, and any adverse reactions. 
• Informed consent: Make sure that the patient has been properly informed of the procedure's risks and benefits, especially when contrast is used. 
• Contrast reactions: Be prepared to identify and respond to signs of mild (nausea, rash) to severe (anaphylaxis, hypotension) contrast media reactions. 
• Hydration protocols: Post-scan hydration may be encouraged to help eliminate contrast media, especially in patients with renal impairment. 
• Radiation safety: Advocate for low-dose protocols and cumulative dose tracking in patients with frequent imaging. 
• Interdisciplinary communication: Collaborate with radiology, physicians, and transport staff to ensure smooth workflow and accurate information exchange. 
• Patient positioning: Understand common positioning techniques to assist with patient comfort and image quality. 
• Special populations: Provide tailored care for pediatric, pregnant, or critically ill patients undergoing CT scans. 
• Post-procedure monitoring: Monitor for delayed contrast reactions or symptoms of renal dysfunction in at-risk populations. 

Being well-informed allows nurses to ensure both procedural success and patient safety during CT imaging. 

Are CT scans and CAT scans the same thing? 

Yes, "CT scan" and "CAT scan" refer to the same procedure. The term "CAT scan" (computed axial tomography) is older, while "CT scan" (computed tomography) is now more commonly used. Both describe the same imaging technology that captures detailed anatomical information to assist in clinical diagnosis.