Calculator Inputs
Use the responsive grid below. Large screens show three columns, medium screens show two, and mobile screens show one.
Example Data Table
These rows are illustrative samples for testing layouts, exports, and graph behavior.
| Protocol | Isotope | Activity (MBq) | Weight (kg) | Half-life (h) | Uptake (%) | Bio Half-life (h) | Dose Coeff. | S-value |
|---|---|---|---|---|---|---|---|---|
| Bone Scan Sample | Technetium-99m | 740 | 70 | 6.01 | 35 | 4 | 0.0057 | 0.0008 |
| PET Uptake Sample | Fluorine-18 | 370 | 75 | 1.83 | 18 | 1.5 | 0.019 | 0.0021 |
| Thyroid Sample | Iodine-123 | 15 | 68 | 13.22 | 22 | 10 | 0.14 | 0.003 |
| Therapy Sample | Iodine-131 | 3700 | 80 | 192.5 | 28 | 48 | 0.22 | 0.0085 |
Formula Used
The net administered activity removes leftover syringe activity from the entered activity value.
This is the physical decay constant using the radionuclide half-life.
This is the biological clearance constant. Enter zero if you want physical decay only.
Effective half-life combines physical decay and biological clearance into one usable value.
This gives the physically decayed activity after the chosen elapsed time.
This estimates retained activity inside the target compartment after uptake and clearance.
Cumulated activity is the time-integrated activity used in internal dosimetry calculations.
The absorbed dose estimate uses cumulated activity and the entered S-value.
The effective dose estimate uses the entered dose coefficient k in mSv per MBq.
This approximates exposure rate using the gamma constant, activity in GBq, and distance from the source.
How to Use This Calculator
1) Enter protocol details
Select a preset isotope or choose a custom entry. Add the administered activity, unit, and patient weight.
2) Set timing and decay inputs
Enter physical half-life, elapsed hours, and biological half-life. The page combines these to estimate effective clearance.
3) Add uptake and dose factors
Provide uptake percentage, residual percentage, effective dose coefficient, and S-value for the selected organ or target region.
4) Review exposure estimate
Optionally enter distance and gamma constant to estimate a simple exposure rate at the selected time point.
5) Calculate and inspect results
Press Calculate Dose. The result appears above the form, directly below the header, exactly as requested.
6) Export your output
Use the CSV and PDF buttons to export the result summary or the example table for reporting and review.
Frequently Asked Questions
1. What does this calculator estimate?
It estimates net administered activity, physical decay, retained target activity, effective half-life, cumulated activity, absorbed dose, effective dose, and a simple exposure-rate approximation.
2. Can I use MBq or mCi?
Yes. Enter the activity value, then choose either MBq or mCi. The calculator converts units automatically and shows both in the results.
3. Why include residual syringe activity?
Residual activity reduces the true delivered activity. Including it improves the net administered estimate and gives a more realistic dosimetry workflow.
4. What is the role of biological half-life?
Biological half-life models clearance from the body or target organ. Combined with physical half-life, it produces the effective half-life used in retention and cumulated activity calculations.
5. What is an S-value here?
The S-value converts cumulated activity into absorbed dose. It depends on radionuclide, target region, geometry, and dosimetry model assumptions.
6. What does the dose coefficient represent?
It is the effective dose per unit administered activity. Multiplying it by net administered activity gives a quick effective-dose estimate in mSv.
7. What does the graph show?
The graph compares physical decay against retained target activity over time. This helps visualize timing effects, uptake behavior, and biological clearance.
8. Is this suitable for direct clinical decisions?
No. It is an educational and workflow-support calculator. Clinical decisions require validated protocol data, physician oversight, and site-approved dosimetry tools.