Booking a CT scan in Ontario starts with your doctor, not the scanner. You need a requisition first, and then you can choose where to book. This guide walks through each step, from getting the requisition to receiving your results, with the details that most often cause delays.
Quick Facts: Booking a CT Scan in Ontario
A diagnostic CT scan requires a requisition from a physician or nurse practitioner. The only self-referral route for CT is the Ontario Lung Screening Program, where eligibility is assessed by the program. CT scans are OHIP-insured when medically necessary, and the clinic confirms coverage for your exam when you book. At King City Diagnostic Imaging, CT is by appointment only, and most exams are booked within one to two business days, depending on availability.
Before you start: what a CT requisition is
Knowing how to book a CT scan in Ontario is mostly about having the right information in hand when you call. In Ontario, CT examinations require a requisition from an authorized healthcare provider such as a physician or nurse practitioner, and a diagnostic CT cannot be booked by referring yourself. If you are new to how referrals work across imaging, our guide to referrals for diagnostic imaging in Ontario covers each type of exam.
CT is by appointment only at King City Diagnostic Imaging.
Step 1: Get a requisition from your doctor or nurse practitioner
A CT requisition is the order that tells the imaging team which part of your body to scan and why. The clinical information on it helps the team choose the right scan protocol and decide whether contrast is needed. You cannot book a diagnostic CT without one, and you cannot refer yourself. If you are unsure whether you qualify for the lung screening program, our guide to CT scans in Ontario explains how it works.
Step 2: Check your requisition before you leave
A few details prevent delays at booking:
- Your full name and health card details are correct
- The area to be scanned is clearly stated
- The referring provider’s name and fax number are included, since that is where your report is sent
- Ask how urgent the scan is, because the priority your requisition carries affects how soon you are scheduled
Step 3: Decide where to be scanned
The facility named on your requisition is not always the only choice. Wait times differ between facilities, even for the same priority level, and Ontario’s guidance is that requisitions for insured services are generally valid at any location providing that service. If you want to compare options, ask your doctor’s office, and read our article on imaging wait times and OHIP coverage. King City Diagnostic Imaging accepts CT requisitions from physicians and nurse practitioners across Toronto and the GTA.
Step 4: Book your appointment
At King City, call 905-539-0555 or book online and upload your requisition. When you book, ask about:
- Whether your exam uses contrast
- Whether a recent blood test is needed before a contrast scan
- Any fasting instructions
- What to tell the technologist, such as pregnancy, kidney disease, diabetes or medications like metformin
If your doctor’s office is booking for you, they can use our CT scan requisition form.
Step 5: Prepare for your scan
Preparation depends on the area being scanned and whether contrast is required. Always follow the instructions on your requisition and from the clinic staff. Our CT scan preparation checklist covers clothing, what to bring, and what to tell the team.
You lie on a table that slides through a ring-shaped scanner, and the scanner takes images in just a few minutes.
Step 6: Attend your appointment
Arrive 15 minutes early and bring your requisition, your Ontario Health Card, a list of your current medications, and any prior imaging reports. The CT technologist will confirm your instructions, and the scanner itself takes images in just a few minutes. If contrast is needed, you may receive it by mouth or through an IV.
Step 7: Get your results
A radiologist analyzes your images within 24 to 48 hours, and sooner when results are urgently needed. The report is faxed to your referring physician right after. Your referring provider discusses the results with you and arranges any follow-up, so contact their office for result questions.
How CT priority levels work
Ontario does not run one CT queue. It runs four, and a radiologist decides which one you are in based on your symptoms, your history and clinical guidelines.
- Priority 1, emergent: target 24 hours
- Priority 2, urgent: target 48 hours
- Priority 3, semi-urgent: target 10 days
- Priority 4, non-urgent: target 28 days
As of June 2026, urgent CT scans averaged one day across Ontario, while non-urgent scans averaged 79 days. The clock Ontario measures starts when the facility receives the order, so the wait you experience can be longer than the published number. Read our article on imaging wait times and OHIP coverage in Ontario for the full picture, and use Ontario Health’s public wait times tool to check current waits.
If you are told the wait is long
If your appointment is further away than you would like, there are reasonable things to ask:
- Whether your requisition can be sent to a facility that can see you sooner
- Whether weekend appointments are available
- Whether an earlier time has opened up
The one exception: lung cancer screening
Diagnostic CT cannot be self-referred, but Ontario runs an organized low-dose CT lung screening program that eligible high-risk people can refer themselves to. Eligibility depends on factors such as age and tobacco history, and a screening navigator runs a formal risk assessment before anyone is accepted. You can have your primary care provider submit a referral or contact a program site directly. Our guide to CT scans in Ontario explains how the program works.
Other imaging at King City
If your provider has requested more than a CT, King City also provides walk-in X-ray, ultrasound, mammography, bone mineral density, FibroScan, vascular ultrasound and cardiology at the same location. Ask our staff when you call about the best way to schedule everything together, or browse our services page.
What to have ready when you call
Have these details in front of you before you phone 905-539-0555 or open the online booking page:
- Your requisition, including the area to be scanned and the referring provider’s fax number
- Your Ontario Health Card
- A list of your current medications and any prior imaging reports
- Any previous reaction to contrast dye or iodine, and whether you have kidney disease, diabetes or take metformin
- Whether you are pregnant or may be pregnant
- The days and times that work for you
Common booking mistakes to avoid
- Waiting until the day of your scan to ask about contrast or fasting
- Cancelling your current appointment before the new one is confirmed
- Assuming the facility printed on your requisition is your only choice
- Forgetting prior imaging reports and your medication list
Where you live may change which guide helps most: Toronto and the GTA, Richmond Hill, Vaughan and Markham, Aurora and Newmarket and North York and Toronto each cover travel and booking details for that area.
Frequently asked questions
Can I book a CT scan without a referral in Ontario?
No, not for a diagnostic CT. The exception is the Ontario Lung Screening Program, which allows eligible high-risk people to self-refer for a low-dose screening CT after a risk assessment.
Can a nurse practitioner order a CT scan?
Yes. A requisition from a physician or nurse practitioner is accepted at King City Diagnostic Imaging.
What if I lose my requisition?
Contact the office that issued it and ask them to send a new copy, or have them send it directly to the clinic.
How long until I get an appointment?
It depends on the priority level on your requisition and the facility. At King City, most exams are booked within one to two business days, depending on availability.
Is a CT scan covered by OHIP?
CT scans are OHIP-insured when they are medically necessary and ordered by a physician or nurse practitioner. Coverage depends on your eligibility and the exam requested, and our staff confirm whether your scan is covered before your exam.
How long does a CT scan take?
The scanner takes images in just a few minutes. Plan for a longer visit overall, because you check in 15 minutes early and the technologist confirms your instructions before the scan.
Do I need a blood test before a CT scan?
Sometimes. A recent blood test (creatinine and eGFR) may be required before a contrast CT. Ask when you book, and tell staff if you have kidney disease, diabetes or take metformin.
Can I choose where to have my CT scan?
In many cases, yes. Ontario’s guidance is that requisitions for insured services are generally valid at any location providing that service. If you are unsure, ask your doctor’s office, or call 905-539-0555 and our staff can check your requisition.
What if my doctor has marked my scan urgent?
Follow your doctor’s direction on where to go. In an emergency, go to the nearest emergency department.
Book your CT scan
With your requisition in hand, call 905-539-0555 or book your appointment online. Learn more about CT scans at King City Diagnostic Imaging.
