Getting a CT scan starts with a doctor’s order. In nearly all cases, you’ll need a physician or other qualified provider to determine that the scan is medically necessary and submit a referral to an imaging facility. The process from that point typically involves insurance approval, minimal preparation, and a scan that takes about 30 minutes total. Here’s what each step looks like.
Getting the Referral
Your primary care doctor or a specialist is the usual starting point. If you’re dealing with unexplained pain, a suspected injury, or symptoms that need further investigation, your doctor evaluates whether imaging will change your diagnosis or treatment plan. If it will, they write an order specifying the body part to be scanned and whether contrast dye is needed.
In an emergency room, the process is faster. The ER physician orders the scan directly, and it’s performed on-site, often within the hour. No prior authorization is needed in true emergencies.
For outpatient scans, you can usually choose where to go. Hospitals, freestanding imaging centers, and academic medical centers all offer CT scanning. Your doctor’s office may suggest a facility, but you’re generally free to pick one that fits your budget or location.
Insurance Approval and Prior Authorization
Many insurance plans require prior authorization before covering a CT scan. This means your doctor’s office submits a request to your insurer explaining why the scan is medically necessary. They may need to document what other tests or treatments you’ve already tried and why imaging is the next logical step. Some large radiology practices handle this paperwork for your doctor’s office, which can speed things up.
Authorization can take anywhere from a few hours to several business days. If your insurer denies the request, your doctor can appeal with additional clinical justification. In practice, most scans ordered for clear diagnostic reasons get approved without much trouble.
Can You Get a CT Scan Without a Doctor?
A small number of screening CT scans are available without a traditional referral. The most well-known is the low-dose CT for lung cancer screening, which the U.S. Preventive Services Task Force recommends for adults aged 50 to 80 who have a 20 pack-year smoking history and currently smoke or quit within the past 15 years. Some facilities and direct-to-consumer imaging companies also offer “whole body” or cardiac calcium scoring scans that you can book yourself, though these are rarely covered by insurance and their clinical value is debated.
For diagnostic scans, where you’re trying to find the cause of a specific symptom, a physician’s order is essentially always required. Imaging facilities won’t perform a diagnostic CT without one.
What It Costs
CT scan prices vary dramatically depending on where you go. A scan of a single body part without contrast typically ranges from $280 on the low end to $1,900 on the high end, with an average around $850 for cash-pay patients. Adding contrast dye increases the cost by $150 to $500.
The biggest price factor is the facility type. A head CT at a hospital runs $1,500 to $3,000, while the same scan at an independent imaging center costs $400 to $800. Chest CTs follow a similar pattern: $1,800 to $3,500 at hospitals versus $500 to $1,000 at imaging centers. Abdominal and pelvic scans, which often require contrast, range from $2,000 to $4,000 at hospitals and $600 to $1,200 at imaging centers.
If you have insurance, your out-of-pocket share depends on your plan’s deductible and coinsurance. If you’re paying cash, call ahead and ask for the cash or self-pay rate, which is often significantly lower than the sticker price.
How to Prepare
Preparation depends on what type of scan you’re getting. For most CT scans with intravenous contrast, fasting beforehand is no longer recommended. Both European and American radiology guidelines now state that you do not need to skip meals before a routine contrast-enhanced scan. The main preparation is staying well-hydrated: drink fluids steadily for 6 to 12 hours before the scan and for 24 hours afterward, especially if you have any kidney concerns.
The exception is scans of the stomach or intestines that use oral contrast. For these, you’ll typically need to fast for at least 4 hours and then drink about a liter of contrast liquid before the scan. Your imaging center will give you specific timing instructions when you schedule.
If you’re receiving sedation for any reason, standard fasting rules apply: no solid food for 6 hours and no clear liquids for 2 hours before the procedure.
You’ll also be asked about allergies (particularly to iodine or contrast dye), whether you’re pregnant, and about your kidney function. A simple blood test to check kidney health is standard before contrast scans. The key threshold radiologists watch is kidney filtration rate: patients with very low kidney function (below 30 on the standard scale) face a higher risk of kidney injury from contrast dye, so the team may adjust the dose or use alternative imaging.
What Happens During the Scan
A CT scanner is not the enclosed tube many people picture. It’s an open, doughnut-shaped ring. You lie on a flat table that slides through the center of the ring, and you can see the room around you the entire time. If you’ve been anxious about claustrophobia, CT scans are far more open than MRI machines.
The technologist positions you on the table, steps into a nearby control room with a window, and communicates through a speaker. You may be asked to hold your breath for a few seconds during certain scans. The actual X-ray exposure lasts only seconds to a few minutes with modern machines. The entire visit, including check-in, positioning, and the scan itself, usually takes about 30 minutes.
If you’re getting intravenous contrast, a technologist or nurse places a small IV line, usually in your arm. When the contrast flows in, you may feel a warm sensation spreading through your body and a brief metallic taste in your mouth. This is completely normal and fades within a minute or two.
Radiation Exposure
CT scans use X-rays, so they do involve radiation. The dose varies by body part. A head CT delivers roughly 2 millisieverts (mSv), a chest CT about 4.4 mSv, and an abdominal CT around 6.8 mSv. For comparison, background radiation from the environment exposes you to about 3 mSv per year just from daily life. A single CT scan is a modest addition to your lifetime exposure, and when the scan is medically indicated, the diagnostic benefit far outweighs the small radiation risk.
Getting Your Results
After your scan, a radiologist reviews the images and writes a report for the doctor who ordered it. In an emergency department, preliminary reads often happen within minutes. For outpatient scans, the turnaround is longer. At academic medical centers, the average time from scan completion to a finalized report has been measured at roughly two hours, though it can stretch longer depending on complexity and staffing.
Your ordering physician typically receives the report within one to three business days and contacts you with results. Many health systems now also post radiology reports to online patient portals, so you may be able to read the findings yourself before your doctor calls. If your results show something urgent, the radiologist contacts your doctor directly and quickly.