Formula & Calculator
Effective Dose Calculator
Effective dose E is the sum over tissues of the product of the tissue weighting factor w_T and the equivalent dose H_T. It is a single quantity that represents the risk of stochastic effects (cancer and heritable effects). It is used for regulatory compliance and for comparing doses from different exposures. The tissue weighting factors are specified by ICRP.
Effective DoseICRPDosimetry
Effective Dose
Nuclear Engineering · Health Physics & Dosimetry
E =
Σ
wT ·
HT
·
E = effective dose ·
wT = tissue weighting factor ·
HT = equivalent dose in tissue
Effective dose E is the sum over tissues of the product of the tissue weighting factor wT
and the equivalent dose HT. It is a single quantity that represents the risk of stochastic effects
(cancer and heritable effects). It is used for regulatory compliance and for comparing doses from different exposures.
The tissue weighting factors are specified by ICRP.
Presets:
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Solve for:
| Tissue | wT | HT (Sv) | Contribution |
|---|
Target: E
Calculation Steps
Ready| Step | Operation | Value |
|---|---|---|
| Enter values and press Calculate | ||
ICRP 103 Tissue Weighting Factors
Sum wT = 1.0
| Tissue | wT |
|---|
E = Σ wT · HT · Sum of wT = 1.0 (ICRP 103) · Used for regulatory compliance
E = Σ w_T H_T
Effective Dose Calculator
Variables
| Symbol | Quantity | Unit |
|---|---|---|
| E | Effective Dose | Sv |
| w_T | Tissue Weighting Factor | dimensionless |
| H_T | Equivalent Dose in Tissue T | Sv |
What it means
Effective dose is a measure of overall risk. It allows comparison of different exposure scenarios.
Worked example
Effective Dose from CT Scan (E = Σ wT HT)
Radiation Dosimetry
Scenario: A patient undergoes a contrast‑enhanced abdomen/pelvis CT. The organ‑specific equivalent doses (HT) are estimated from the DLP using conversion coefficients. Using the ICRP‑103 tissue weighting factors (wT), the effective dose (E) is calculated to assess the overall stochastic risk. The result helps in justifying the examination and comparing with diagnostic reference levels.
| Tissue | wT | HT (mSv) | wT × HT (mSv) |
|---|---|---|---|
| Stomach | 0.12 | 12.0 | 1.44 |
| Colon | 0.12 | 10.0 | 1.20 |
| Liver | 0.04 | 8.0 | 0.32 |
| Lungs | 0.12 | 2.0 | 0.24 |
| Gonads | 0.08 | 3.0 | 0.24 |
| Bone marrow | 0.12 | 5.0 | 0.60 |
| Oesophagus | 0.04 | 4.0 | 0.16 |
| Remainder | 0.12 | 6.0 | 0.72 |
| Total Effective Dose | 4.92 mSv | ||
1Obtain organ equivalent doses (HT) using software (e.g., ImPACT, NCICT) or from CT dose reports.
2Apply ICRP‑103 tissue weighting factors (wT) for each radiosensitive organ.
3Multiply each HT by its wT and sum over all tissues (including the remainder).
Effective Dose
E = 4.92 mSv
This is comparable to the typical effective dose for a CT abdomen/pelvis (~8 mSv); the result is used for risk communication.
Occupational Effective Dose (E = Σ wT HT)
Radiation Dosimetry
Scenario: An interventional cardiologist performs a coronary angioplasty using fluoroscopy. The dosimeters placed at multiple body locations provide organ‑equivalent doses (HT) for the radiation‑sensitive tissues. The effective dose is calculated using the same ICRP‑103 weighting scheme to assess the professional risk and to ensure compliance with occupational dose limits.
| Organ | wT | HT (mSv) | wT × HT (mSv) |
|---|---|---|---|
| Lungs | 0.12 | 1.0 | 0.12 |
| Bone marrow | 0.12 | 0.8 | 0.096 |
| Thyroid | 0.04 | 4.0 | 0.16 |
| Oesophagus | 0.04 | 0.5 | 0.02 |
| Gonads | 0.08 | 0.2 | 0.016 |
| Remainder | 0.12 | 1.0 | 0.12 |
| Total Effective Dose | 0.53 mSv | ||
1Measure or estimate organ doses (HT) from multiple dosimeter readings or from Monte Carlo simulations.
2Apply the wT values from ICRP‑103 to each organ dose.
3Sum the products to get the effective dose for the procedure.
Effective Dose
E = 0.53 mSv
This single procedure dose is small; annual accumulation may approach the occupational limit.
PET/CT Effective Dose (E = Σ wT HT)
Radiation Dosimetry
Scenario: A patient with lymphoma undergoes an FDG‑PET/CT scan for staging. The CT component contributes mainly to organ doses, while the PET component adds uniform whole‑body dose. The organ‑specific equivalent doses are combined with tissue weighting factors to calculate the effective dose. This is essential for evaluating the benefit‑risk balance in oncology imaging.
| Organ | wT | HT (mSv) | wT × HT (mSv) |
|---|---|---|---|
| Lungs | 0.12 | 6.0 | 0.72 |
| Bone marrow | 0.12 | 5.0 | 0.60 |
| Stomach | 0.12 | 4.5 | 0.54 |
| Colon | 0.12 | 3.8 | 0.456 |
| Bladder | 0.04 | 12.0 | 0.48 |
| Gonads | 0.08 | 1.0 | 0.08 |
| Thyroid | 0.04 | 2.5 | 0.10 |
| Remainder | 0.12 | 4.0 | 0.48 |
| Total Effective Dose | 3.46 mSv | ||
1Obtain organ doses from the PET/CT system's dose report or from MIRD phantoms.
2Multiply each organ dose by its corresponding ICRP‑103 wT.
3Sum the weighted doses to get the effective dose, which is used to compare with reference levels.
Effective Dose
E = 3.46 mSv
Typical for a PET/CT; the dose is justified by the clinical benefit of accurate staging.
Common mistakes
- Using HT (equivalent dose) instead of E (effective dose): The formula sums equivalent doses; if you use absorbed doses, the weighting factors are missing.
- Confusing wT with wR: wT sums to 1; wR is for radiation type.
- Using old ICRP 60 wT values: ICRP 103 has revised values (e.g., breast now 0.12 instead of 0.05).
Applications
- Dose reporting: The legal quantity for reporting worker and public doses.
- Risk assessment: Correlates with the probability of stochastic effects.
- Medical physics: Used to compare the risk of different diagnostic procedures.