Common radiation units:
- Sievert (Sv): equivalent dose
- Gray (Gy): absorbed dose
- Becquerel (Bq): activity
- Rem/Rad: US dose units
- Curie (Ci): US activity unit
Key relationships:
- 1 Sv = 100 rem
- 1 Gy = 100 rad
- 1 Ci = 3.7 × 10¹⁰ Bq
Early Units:
The roentgen (R) was defined in 1928 as the first standardized unit of radiation exposure. The rad (radiation absorbed dose) and rem (roentgen equivalent man) were developed in the 1950s to measure absorbed dose and biological effect, respectively.
SI Units:
The International System (SI) adopted the gray (named after L.H. Gray) for absorbed dose and the sievert (named after Rolf Sievert) for equivalent dose in the 1970s. The becquerel (named after Henri Becquerel) replaced the curie as the unit of radioactivity.
Transitional Period:
Many countries have transitioned to SI units, but the US still commonly uses traditional units (rem, rad, curie). This necessitates conversion between systems in international scientific communication.
Sievert/Rem Units Used For:
- Radiation protection standards
- Occupational dose limits
- Public health exposure assessments
- Effective dose calculations
Gray/Rad Units Used For:
- Radiation therapy dosing
- Industrial irradiation processes
- Radiographic imaging dose
- Material testing
Activity Units Used For:
- Nuclear medicine (MBq, mCi)
- Laboratory radiation sources
- Environmental monitoring
- Radiopharmaceutical specifications
Radiation Unit Conversion Calculator
Conversion Result
Use the converter above to calculate different values and units
What are Radiation Measurements?
Radiation measurements quantify different aspects of ionizing radiation, including absorbed dose (energy deposited in matter), equivalent dose (biological effect considering radiation type), activity (rate of radioactive decay), and exposure (ionization in air).
Different radiation units exist because radiation has varied effects depending on the type of radiation, the tissue exposed, and the context of measurement. The International System (SI) uses sievert, gray, and becquerel, while the older system used in the US includes rem, rad, and curie.
Learn more from Centers for Disease Control (CDC) or International Atomic Energy Agency (IAEA).
Common Radiation Conversions
| Type | SI Unit | Traditional Unit | Conversion |
|---|---|---|---|
| Absorbed Dose | Gray (Gy) | rad | 1 Gy = 100 rad |
| Equivalent Dose | Sievert (Sv) | rem | 1 Sv = 100 rem |
| Activity | Becquerel (Bq) | Curie (Ci) | 1 Ci = 3.7 × 10¹⁰ Bq |
| Exposure | C/kg | Roentgen (R) | 1 R = 2.58 × 10⁻⁴ C/kg |
Prefixed Units
| Prefix | Symbol | Factor | Example |
|---|---|---|---|
| micro | μ | 10⁻⁶ | 1 μSv = 0.000001 Sv |
| milli | m | 10⁻³ | 1 mSv = 0.001 Sv |
| kilo | k | 10³ | 1 kBq = 1,000 Bq |
| mega | M | 10⁶ | 1 MBq = 1,000,000 Bq |
| giga | G | 10⁹ | 1 GBq = 10⁹ Bq |
Practical Applications of Radiation Conversions
Medical Physics
- Converting between dose units for radiation therapy treatment planning
- Calculating activity of radiopharmaceuticals for nuclear medicine procedures
- Estimating patient radiation exposure from diagnostic imaging
- Ensuring radiation safety for medical personnel
Radiation Protection
- Converting between equivalent dose units to verify compliance with regulations
- Translating international standards to local requirements
- Designing radiation shielding based on dose calculations
- Training radiation workers on exposure limits in appropriate units
Environmental Monitoring
- Converting between activity units for reporting radioactive contamination
- Assessing natural background radiation levels
- Monitoring nuclear facilities for compliance with discharge limits
- Long-term tracking of environmental radiation trends
Research & Industry
- Converting between measurement systems for international research collaboration
- Calibrating radiation detection instruments
- Quality control for industrial radiography
- Food irradiation dose verification
Emergency Response
- Rapid conversion between units during radiological incidents
- Comparing measured values against emergency action levels
- Public communication of radiation risks in appropriate units
- Calculating protective action distances based on dose projections
Educational Resource
This educational video from the Health Physics Society explains the essential radiation units including sievert, gray, becquerel, rem, rad, and curie. It clearly illustrates the differences between dose, equivalent dose, and activity measurements while providing practical examples of their applications in radiation safety and medical physics.
Radiation Conversion Resources
Get our comprehensive radiation conversion chart showing relationships between sievert, gray, becquerel and other radiation units for quick reference in medical physics, radiation protection, and health physics applications.
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Radiation Conversion FAQs
Find answers to common questions about radiation measurements and conversions.