Canadian CT Head Rule Calculator

Canadian CT Head Rule Calculator — Determine Need for CT Scan in Head Injury

A validated clinical decision rule to determine whether CT imaging is indicated for patients with minor head injuries. Helps reduce unnecessary radiation exposure and healthcare costs.

Step 1: Patient Information

Patient Age (years)

45 years

Glasgow Coma Scale (GCS) Score at 2h post-injury

Injury Mechanism

About the Canadian CT Head Rule

The Canadian CT Head Rule was developed to identify patients with minor head injury who require CT imaging. It has high sensitivity for clinically important brain injury while reducing unnecessary scans.

Step 2: High-Risk Criteria

High-Risk Factors (For Neurological Intervention)

If ANY high-risk factor is present → CT is indicated.

GCS score < 15 at 2 hours after injury

Suspected open or depressed skull fracture

Signs of basal skull fracture (raccoon eyes, Battle’s sign, hemotympanum, CSF otorrhea/rhinorrhea)

≥ 2 episodes of vomiting

Age ≥ 65 years

Medium-Risk Factors (For Brain Injury on CT)

If NO high-risk factors but ANY medium-risk factor is present → CT is indicated.

Amnesia before impact ≥ 30 minutes

Dangerous mechanism (pedestrian struck, ejected from vehicle, fall from height > 1m/5 stairs)

Important Considerations

This tool is for adults (≥16 years) with minor head injury (GCS 13-15) within 24h of injury. Not for patients with coagulopathy, seizure, or focal neurological deficit. Always use clinical judgment.

CT Decision Results

Summary

Criteria Details

Statistics

CT Recommendation: Not Yet Calculated

Enter patient information and select criteria to calculate recommendation.

High-Risk Criteria

Medium-Risk Criteria

CT Sensitivity

–

CT Specificity

–

Criteria Assessment

Criterion	Status	Clinical Significance

Validation Statistics

Rule Performance

Evidence-Based Decision Rule

The Canadian CT Head Rule has 100% sensitivity for detecting need for neurological intervention and would result in a CT scan rate of approximately 52%, compared to current practice rates of 70-80%.

Important Medical Disclaimer

This tool is for educational purposes only. Clinical decisions should be made by qualified healthcare professionals considering the full clinical context. This calculator does not replace clinical judgment.

View Full Disclaimer