Effective dose
Effective dose is a quantity used as a measure of the risk of long-term effects from irradiation of the whole human body and its individual organs and tissues, taking into account their radiosensitivity. The calculator allows for the estimation of the effective radiation dose in a CT scan using the absorbed dose over the entire CT examination (DLP).
Effective Dose Calculator
The method for assessing the effective dose in CT scans is based on measurements of the absorbed dose in physical phantoms that simulate the patient's body. The patient's body is divided into two anatomical regions (head + neck and torso), modeled as cylinders with diameters of 16 cm and 32 cm, respectively. For pediatric patients, the torso may be modeled using a 16 cm diameter cylinder. Measurements are taken at four points at a depth of 1 cm and at the center of the phantom.
E (effective dose) is the sum of the weighted absorbed doses in all human organs and tissues. It is calculated using:
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Radiation weighting factors (accounting for penetration ability; for X-rays, this factor is 1), and
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Tissue weighting factors (accounting for the radiosensitivity of specific tissues and organs).
The effective dose serves as a measure of the biological risk of radiation exposure during a CT scan and allows for direct comparison with the effective doses from other X-ray diagnostic procedures. The unit of measurement is millisieverts (mSv).
The effective dose is calculated using the formula:
E = DLP × EDLP, where:
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DLP (Dose Length Product) – Total absorbed dose over the entire CT scan (in mGy·cm).
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EDLP – Dose conversion coefficient for the corresponding anatomical region (in mSv/(mGy·cm).
The values of the dose conversion coefficients depend on the examined body region and the patient's age.
| Anatomical Region | ||||||
|---|---|---|---|---|---|---|
| 0 - 0,5 | 0,5 - 2 | 2 - 7 | 7 - 12 | 12 - 17 | adults | |
| 16 cm phantom | ||||||
| Head | 0,0059 | 0,0048 | 0,0035 | 0,0027 | 0,0018 | 0,0014 |
| Neck | 0,022 | 0,018 | 0,013 | 0,011 | 0,0073 | 0,0060 |
| Head/Neck | 0,0078 | 0,0066 | 0,0051 | 0,0043 | 0,0030 | 0,0025 |
| Chest | 0,026 | 0,020 | 0,014 | 0,011 | 0,0069 | - |
| Abdomen | 0,031 | 0,024 | 0,017 | 0,013 | 0,0079 | - |
| Pelvis | 0,034 | 0,027 | 0,019 | 0,014 | 0,0087 | - |
| Lower extremities | 0,0015 | 0,00099 | 0,00055 | 0,00036 | 0,00016 | - |
| Chest/Abdomen | 0,028 | 0,022 | 0,016 | 0,012 | 0,0073 | - |
| Abdomen/Pelvis | 0,032 | 0,026 | 0,018 | 0,014 | 0,0083 | - |
| Chest/Abdomen/Pelvis | 0,030 | 0,024 | 0,017 | 0,013 | 0,0078 | - |
| Whole body | 0,019 | 0,016 | 0,013 | 0,012 | 0,0087 | - |
| 32 cm phantom | ||||||
| Chest | 0,059 | 0,047 | 0,033 | 0,026 | 0,016 | 0,012 |
| Abdomen | 0,072 | 0,056 | 0,039 | 0,030 | 0,018 | 0,014 |
| Pelvis | 0,077 | 0,060 | 0,042 | 0,033 | 0,020 | 0,015 |
| Lower extremities | 0,0027 | 0,0018 | 0,0010 | 0,00068 | 0,00030 | 0,00020 |
| Chest/Abdomen | 0,065 | 0,051 | 0,036 | 0,028 | 0,017 | 0,013 |
| Abdomen/Pelvis | 0,075 | 0,059 | 0,041 | 0,031 | 0,019 | 0,015 |
| Chest/Abdomen/Pelvis | 0,069 | 0,054 | 0,038 | 0,029 | 0,018 | 0,014 |
| Whole body | 0,043 | 0,038 | 0,031 | 0,027 | 0,020 | 0,017 |