Calculator inputs
Example data table
| Agent | Weight (kg) | Dose (mmol/kg) | Concentration (mmol/mL) | Calculated mmol | Volume (mL) |
|---|---|---|---|---|---|
| Gadavist | 70 | 0.10 | 1.00 | 7.00 | 7.00 |
| Dotarem | 65 | 0.10 | 0.50 | 6.50 | 13.00 |
| Eovist | 80 | 0.025 | 0.25 | 2.00 | 8.00 |
| Elucirem | 60 | 0.05 | 0.50 | 3.00 | 6.00 |
Formula used
| Step | Formula | Meaning |
|---|---|---|
| 1 | Weight in kg = Weight in lb / 2.2046226218 |
Converts pounds to kilograms when needed. |
| 2 | Total mmol = Weight (kg) × Ordered dose (mmol/kg) |
Finds the amount of gadolinium chelate expressed in mmol. |
| 3 | Volume (mL) = Total mmol / Concentration (mmol/mL) |
Converts the ordered mmol amount into injectable liquid volume. |
| 4 | Rounded volume = round(Volume / Increment) × Increment |
Aligns the draw-up value to your chosen syringe marking increment. |
| 5 | Session volume = Rounded single volume × Planned injections |
Estimates total contrast volume across the complete planned session. |
How to use this calculator
- Enter patient weight and choose kilograms or pounds.
- Select a contrast agent preset or switch to custom dosing.
- Adjust rounding, syringe size, and planned injection count.
- Optionally enter eGFR, dialysis status, and a protocol note.
- Press Calculate dose to display the summary above the form.
- Review the rounded volume, total mmol, syringe utilization, and advisories.
- Use the CSV or PDF buttons to document the calculated output.
FAQs
1) What does this calculator estimate?
It estimates contrast dose in mmol and mL from patient weight, ordered mmol/kg, and product concentration. It also shows rounded draw-up volume, session totals, and syringe planning details.
2) Why are some agents lower in mL/kg?
Different agents have different labeled concentrations and standard protocols. A 1.0 mmol/mL product needs less liquid volume than a 0.5 mmol/mL product for the same mmol/kg target.
3) Does the calculator automatically reduce dose for low eGFR?
No. It only shows a warning. Actual contrast use in reduced kidney function should follow current labeling, radiologist approval, and local policy rather than an automatic formula.
4) When should I use custom mode?
Use custom mode for site-specific protocols, research workflows, or products not listed in the presets. Enter the ordered mmol/kg and concentration exactly as your protocol specifies.
5) Why does the rounded volume differ from the exact value?
Rounded volume reflects the selected syringe increment. This supports practical draw-up workflow, but the displayed exact value remains visible so staff can compare both numbers.
6) Can I use pounds instead of kilograms?
Yes. The calculator converts pounds to kilograms internally before calculating dose. The converted kilogram value is shown again in the result summary.
7) What does syringe utilization mean?
It shows how much of the selected syringe size would be filled by one rounded injection. Values above 100% indicate a larger syringe or alternate setup is needed.
8) Are the export buttons useful for documentation?
Yes. CSV is convenient for spreadsheets and audit logs, while PDF is helpful for saving a printable summary of the patient inputs and calculated outputs.