This guideline summarizes suggested wait times for common indications where Computed Tomography (CT) is the recommended first imaging test. The purpose is to inform primary care practitioners of how referrals are prioritized by Radiologists and Radiology departments across the province. This guideline is an adaptation of the British Columbia Radiological Society (BCRS) CT Prioritization Guidelines (2013). 1 Management of the listed clinical problems is beyond the scope of this guideline. However, in some cases, notes and alternative tests are provided for additional clinical context. Primary care practitioners are encouraged to consult a Radiologist if they have any concerns or questions regarding which appropriate imaging test to choose for a problem. If in doubt consult with a Radiologist and review provincial guidance materials. 2   # Background
The 2013 BCRS CT Prioritization Guidelines were developed to provide imaging departments with a consistent, provincial approach to prioritizing commonly ordered CT tests according to suggested maximum wait times. The BCRS guidelines were developed by consensus and are based on BC expert opinion with representation of Radiologists from across the province. Several considerations apply:
- These are guidelines, and as such, are designed to apply in general terms. They are not intended to replace clinical judgement or practitioner-to-practitioner discussion. - Prioritization levels were selected to match other similar guidelines for Magnetic Resonance Imaging (MRI) and Ultrasound (US) and are typically assigned by Radiologists rather than referring practitioners. - These guidelines should not be applied rigidly to each case, as varying clinical factors may shift an indication from one priority level to another. - Access to CT and the ability to respond to CT requests will depend on resources and local availability.
- Providing detailed patient information is essential to aid with the prioritization process.
- The clinical topics included in this guideline represent broad examples, and do not encompass all possible scenarios or all requirements for CT examinations.

# Priority Level Definitions
The priority levels defined below (Table 1) are in alignment with the Canadian Association of Radiologists national designation Five Point Classification System. 3 

# P1
An examination immediately necessary to diagnose and/or treat life-threatening disease. Such an examination will need to be done either stat or not later than the day of the request.
Immediately to 24 hours

# P2
An examination indicated within one week of a request to resolve a clinical management imperative. Maximum 7 calendar days

# P3
An examination indicated to investigate symptoms of potential importance. Maximum 30 calendar days

# P4
An examination indicated for long-range management or for prevention. Maximum 60 calendar days

# P5
Timed follow-up exam or specified procedure date recommended by Radiologist and/or clinician.
Source: Adapted from the Canadian Association of Radiologists National Maximum Wait Time Access Targets for Medical Imaging.

# Prioritization of Potential Diagnoses
CT is widely indicated for and includes but is not limited to the following 4  The following potential diagnoses, where CT is the recommended first test, are grouped according to body system and then further subdivided into priority levels. For each system, an overview table is presented followed by a more detailed table outlining additional notes and alternative tests where CT may be less appropriate due to ionizing radiation exposure.
For CT also consider the patient risk of radiation exposure, refer to Appendix A: Radiation Exposure.
Referring practitioners should include clear, pertinent clinical history on radiology requisitions to assist the triaging/ prioritizing of examinations and interpretation of images and may consider noting the priority directly on the requisition where possible. 

# Pediatric
Consider alternatives to CT, if appropriate, to reduce radiation exposure for pediatric patients. See Appendix A: Radiation Exposure, for more information.