A Computed Tomography (CT) scan is a non-invasive medical imaging technique that uses specialized X-ray equipment to create detailed, cross-sectional images of the body. For diagnosing kidney stones, the CT scan of the Kidneys, Ureters, and Bladder (CT KUB) is the preferred method due to its speed and high accuracy. This technique provides detailed information about the stone’s size, exact location, and whether it is causing a blockage. CT KUB can visualize nearly all types of stones, including those not visible on a standard X-ray, which is crucial for determining the appropriate treatment plan.
The Actual Imaging Time
The time a patient is actively inside the CT scanner receiving radiation is very brief, often lasting only a few minutes. For a non-contrast CT KUB, the standard protocol for kidney stone detection, the active scanning time can be as fast as seconds. This quick process is possible because the scan focuses only on the abdomen and pelvis and does not require the delayed imaging phases associated with contrast dye.
During the procedure, the patient lies on a motorized table that passes through the ring-shaped scanner. The technologist, operating from an adjacent control room, instructs the patient to remain perfectly still. They may also ask the patient to hold their breath for short intervals. This breath-holding prevents motion blur, ensuring the sharp images required to accurately measure and locate the stone. The short duration of the active scan is an advantage for patients experiencing severe pain from renal colic.
Preparing for the CT Scan
The time spent preparing for the procedure is often longer than the actual scan itself. Preparation begins with administrative tasks, such as check-in, verifying insurance, and signing consent forms. Patients are then asked to change into a hospital gown and remove all metal objects, including jewelry and belts. Metal must be removed because it can interfere with the X-ray beams and distort the images.
Preparation for a non-contrast CT KUB is straightforward, usually requiring no special dietary restrictions or fasting. Patients are encouraged to be well-hydrated, as adequate fluid intake helps outline the urinary structures more clearly. If the physician suspects complications like infection or a different underlying issue, intravenous access may be necessary for later contrast administration. If contrast is required, this step adds time for IV placement and pre-scan allergy checks.
Total Appointment Duration and Variables
The total time commitment for a CT scan appointment, from arrival to departure, is typically between 45 minutes and 1.5 hours, depending on various facility-specific factors. The greatest variable is often the facility’s volume and schedule, which dictates the waiting time before the technologist is ready to begin the procedure. A busy hospital or imaging center can lead to a longer wait in the reception area.
If the scan is performed without contrast, the total time is closer to the shorter end of the range, as IV placement or post-injection observation is unnecessary. When contrast material is administered, the duration increases. Time is needed for the dye to circulate and for a mandatory waiting period to monitor for delayed allergic reactions. This observation period alone can add 15 to 30 minutes to the total appointment time.
Other factors influencing the duration include the time taken for the technologist to prepare the machine and position the patient correctly on the table. Though the radiologist reviews the images shortly after the scan is completed, the patient is usually free to leave once the technologist confirms the images are technically sufficient for diagnosis. The final, detailed report is then sent to the ordering physician within a few days.