Getting a CT scan almost always starts with a referral from a healthcare provider. You cannot walk into most imaging centers and request one on your own. A physician, nurse practitioner, or physician assistant must order the scan based on your symptoms or medical condition, and the order needs to document why the scan is medically necessary. There are a few exceptions for elective, self-pay scans, but for the standard path, here’s how the process works from start to finish.
Who Can Order a CT Scan
Federal rules require that all diagnostic imaging be ordered by a treating physician or practitioner, meaning someone who is actively managing your care for a specific medical problem. That includes MDs, DOs, nurse practitioners, clinical nurse specialists, and physician assistants. The key requirement is that the person ordering the scan intends to use the results to guide your treatment.
Your primary care doctor is the most common starting point. If you’re experiencing symptoms that warrant imaging, such as persistent abdominal pain, a suspicious lump, unexplained neurological symptoms, or a possible fracture, your doctor can write the order directly. Specialists like neurologists, oncologists, or orthopedic surgeons also order CT scans routinely. If you visit an emergency room or urgent care center, the ER physician can order one on the spot without any prior authorization.
What Counts as Medically Necessary
Insurance companies and Medicare only cover CT scans that are “reasonable and necessary” for your specific symptoms. That means your provider needs to document signs, symptoms, or abnormal findings that justify the scan. A complaint of “periodic headaches” alone, for example, may not be enough. But headaches paired with vision changes, a history of cancer, or abnormal neurological exam findings would typically meet the threshold.
There’s no blanket rule requiring you to try other tests first. Your doctor can order a CT scan as the initial diagnostic test if your symptoms support it. However, screening scans done without any symptoms, complaints, or personal history of disease are generally not covered unless a specific law authorizes them. If your claim lacks documentation of medical necessity, it can be denied.
Insurance and Prior Authorization
Many insurance plans require prior authorization before they’ll pay for a CT scan performed in an outpatient setting. UnitedHealthcare, for instance, requires prior authorization for outpatient CT scans, MRIs, and PET scans on most commercial plans. Your doctor’s office typically handles this process by submitting clinical information to the insurer, who then approves or denies the request. This can take anywhere from a few hours to several business days depending on the insurer.
There are notable exceptions. Authorization is not required for scans performed in an emergency room, an observation unit, an urgent care center, or during a hospital stay. Medicare Advantage plans through UnitedHealthcare also don’t require prior authorization for CT scans, MRIs, or MRAs. If your insurance denies the request, your doctor can appeal with additional clinical documentation.
How Much a CT Scan Costs
Where you get your scan matters more than almost anything else when it comes to price. The national averages paint a stark picture:
- Outpatient imaging center: about $525
- Hospital inpatient: about $4,750
- Emergency room: the inpatient fee plus roughly $2,000 on top
If your scan isn’t urgent, asking your doctor to send the order to a freestanding imaging center rather than a hospital-based facility can save you thousands of dollars, even with insurance. Many imaging centers post their self-pay prices online, and some offer cash-pay discounts that undercut what you’d pay through insurance with a high deductible. It’s worth calling ahead and comparing prices at two or three facilities before scheduling.
Getting a CT Scan Without a Referral
A small but growing number of scans are available on a self-pay, elective basis without a traditional referral. The most common example is a coronary calcium scan, which screens for calcium buildup in the arteries as an indicator of heart disease risk. These typically cost between $100 and $400 out of pocket, with some facilities offering them for as little as $60. Insurance rarely covers them because they’re considered elective screening rather than diagnostic.
Some direct-to-consumer imaging companies now offer full-body or organ-specific CT scans that you can book yourself. These are entirely self-pay. Keep in mind that elective screening scans come with trade-offs: they can detect things that turn out to be harmless but lead to additional testing, costs, and anxiety. If you’re considering this route, it helps to have a primary care doctor who can interpret the results and advise you on next steps.
How to Prepare for the Scan
Most CT scans require little preparation. If your scan doesn’t involve contrast dye, there’s generally no fasting requirement. You show up, change into a gown if needed, and the scan itself takes anywhere from 10 to 30 minutes depending on the body part being imaged.
Scans that use contrast dye (injected through an IV or sometimes swallowed as a drink) require more planning. You’ll typically need to stop eating about two and a half hours before the exam, though clear liquids like water, black coffee, apple juice, or broth are usually fine up to two hours before. You can take your regular medications with water on the normal schedule.
If you’ve ever had a reaction to contrast dye, or if you’re allergic to iodine, tell the imaging team before the procedure. Certain patients also need a blood test to check kidney function before receiving IV contrast. This includes people with a history of kidney disease, those taking certain medications like metformin, and those who have been acutely ill in the past week with conditions that could affect the kidneys (dehydration, vomiting, sepsis, or inability to eat or drink for 24 hours or more). For healthy outpatients with no risk factors, the kidney function test is usually not required.
What Happens After the Scan
Once the images are captured, a radiologist reviews them and writes a formal report. Most imaging centers deliver results to your referring provider within 24 to 48 hours, though complex cases can take longer. The report is also frequently available through the facility’s patient portal.
Your doctor will typically discuss the findings with you at a follow-up appointment or through a phone call. If the scan reveals something that needs urgent attention, the radiologist may contact your doctor directly on the same day. For routine scans, expect to wait a few days before you hear back. If more than a week passes without any communication, call your doctor’s office to follow up.
Steps to Get the Process Moving
If you believe you need a CT scan, the fastest path forward is straightforward. Schedule an appointment with your primary care doctor or a relevant specialist and describe your symptoms clearly. If your provider agrees that imaging is warranted, they’ll write the order, and their office will handle prior authorization if your insurance requires it. Ask whether the order can be sent to a freestanding imaging center to keep costs down.
If you don’t have a regular doctor, urgent care clinics can evaluate you and order imaging for acute problems. Telehealth visits through services that connect you with licensed providers can also result in imaging orders in some states, though policies vary. For elective scans like coronary calcium scoring, you can contact imaging centers directly to ask about self-pay options and whether they require a referral in your state.