What is an EANM dosage calculator?
An EANM dosage calculator is a tool used to estimate administered activity for nuclear medicine procedures, typically by combining a baseline activity with a weight-based multiplier, then applying protocol limits. In pediatric imaging, this approach helps teams balance image quality with radiation optimization principles.
This page provides a practical calculator interface for learning and protocol planning conversations. It mirrors common workflow logic used in many departments: enter patient weight, baseline activity, minimum/maximum constraints, then generate an adjusted dose suggestion in MBq and mCi.
How this calculator works
1) Weight multiplier interpolation
The calculator uses an interpolated weight-factor curve (demo model inspired by card-based pediatric scaling). The multiplier increases with body weight and is used to scale baseline activity:
Raw Activity = Baseline Activity × Weight Multiplier
2) Apply floor and ceiling
A minimum and maximum activity are then enforced so the suggested value remains inside your protocol limits:
Constrained Activity = min(max(Raw, Minimum), Maximum)
3) Round for operational use
Activity is rounded to a practical dispensing step (1, 5, or 10 MBq), and optional residual activity can be subtracted to estimate net delivered activity.
When to use this tool
- Protocol simulation and staff training.
- Quick cross-check during scheduling or prep.
- Educational walkthroughs for residents/technologists.
It should not replace physician prescription, radiopharmacist review, scanner-specific optimization, or local regulatory documents.
Input tips for better estimates
Use accurate patient weight
Small weight differences can materially change pediatric activities. Use current measured weight whenever possible.
Set protocol-consistent boundaries
Always verify minimum and maximum constraints. Different institutions and imaging systems may require different boundaries, and updates can occur after guideline revisions.
Account for residual activity
Residual in tubing/syringe can reduce delivered activity. Enter an expected residual value to get a more realistic net estimate.
Example workflow
- Select a preset (or choose custom).
- Enter weight, e.g., 22 kg.
- Review baseline/min/max fields.
- Choose rounding (e.g., 5 MBq).
- Click Calculate Activity.
The output displays multiplier, raw estimate, constrained value, rounded dispensed activity, and estimated net activity after residual subtraction.
Clinical governance checklist
- Confirm exam indication and protocol version.
- Document prescribed activity source and calculator assumptions.
- Check contraindications and preparation instructions.
- Verify administered activity in the patient record.
- Review image quality trends and optimize continuously.
Final note
A dosage calculator can improve consistency and speed, but the safest approach is always multidisciplinary: physician, technologist, radiopharmacy, and medical physics working from the same validated protocol set. Use tools like this to support—not replace—clinical judgment.