Radiation Converter

Radiation, in the context of this converter, refers to ionizing radiation dose rate — the rate at which ionizing radiation deposits energy per unit mass of absorbing material per unit time. The SI unit is the gray per second (Gy/s), where 1 gray = 1 joule per kilogram (J/kg). Ionizing radiation encompasses X-rays, gamma rays, alpha particles, beta particles, and neutrons — particles or electromagnetic waves with sufficient energy to remove electrons from atoms, creating ions that can damage biological tissue, electronic components, and structural materials.

Radiation is energy that travels and spreads out from a source. There are two fundamental categories: non-ionizing radiation (radio waves, microwaves, infrared, visible light, ultraviolet) which carries insufficient energy per photon to ionize atoms; and ionizing radiation (X-rays, gamma rays, alpha, beta, neutron) which carries enough energy to ionize atoms and break chemical bonds. This converter focuses on ionizing radiation dose rate — the measure most relevant to radiation protection, medical physics, nuclear power, and nuclear medicine.

In radiation therapy (radiotherapy), medical linear accelerators (LINACs) deliver X-ray or electron beams to tumors at dose rates of 1–10 Gy/min. Modern high-dose-rate (HDR) brachytherapy systems deliver dose rates exceeding 12 Gy/h at the reference distance. FLASH radiotherapy — an emerging treatment modality — uses ultra-high dose rates (>40 Gy/s) delivered in milliseconds. Precise dose rate calibration, using ionization chambers traceable to national standards labs, ensures treatment accuracy to within 2%. Converting between Gy/s, Gy/min, and mGy/s is routine in medical physics quality assurance.

The rad per second (rd/s) is the CGS unit of absorbed dose rate: 1 rd/s = 0.01 Gy/s. The rad (radiation absorbed dose) was the standard unit in the United States until the SI gray was adopted. Many older radiation survey instruments, dosimetry systems, and reactor control systems are calibrated in rad/s or mrad/s. The NRC (Nuclear Regulatory Commission) in the United States still uses rem-based units in some regulatory frameworks, requiring conversion between rad, rem, gray, and sievert for compliance reporting.

The watt per kilogram (W/kg) is numerically equal to gray per second (1 W/kg = 1 Gy/s = 1 J/kg/s), expressing dose rate as power per unit mass. In wireless device safety testing, the Specific Absorption Rate (SAR) for radiofrequency (RF) electromagnetic fields is measured in W/kg and limited to 1.6 W/kg (averaged over 1 g of tissue) in the USA and 2 W/kg (averaged over 10 g) in Europe. While SAR from RF is not ionizing radiation, the W/kg unit is shared, causing occasional confusion that this converter helps resolve.

The sievert per second (Sv/s) converts absorbed dose rate to effective dose rate by applying radiation and tissue weighting factors. For gamma rays and X-rays (w_R = 1), Gy/s and Sv/s are numerically equal. For neutrons, w_R ranges from 5–20 depending on energy. Radiation area monitors in nuclear power plants often report in µSv/h (microsievert per hour), requiring conversion: 1 µSv/h = 2.778 × 10⁻¹⁰ Sv/s. The rem per second (rem/s) is the CGS equivalent: 1 rem/s = 0.01 Sv/s (analogous to the rad-gray relationship).

The SI prefix series for gray per second spans from exagray/second (EGy/s = 10¹⁸ Gy/s) — encountered only in nuclear weapon or reactor accident scenarios — down to attogray/second (aGy/s = 10⁻¹⁸ Gy/s) for ultra-low background radiation measurements. In typical applications: environmental background radiation ≈ 0.1 µGy/s to a few µGy/s; occupational radiation limit ≈ 0.6 µGy/s (50 mSv/year for workers); LINAC therapy ≈ 50 mGy/s; nuclear reactor core during operation ≈ 10⁶ Gy/s.

In space radiation dosimetry, astronauts aboard the International Space Station (ISS) receive approximately 200–500 µSv/day (2.3–5.8 nSv/s), roughly 10–20× the dose rate at Earth's surface. During solar particle events, dose rates can spike to 1 mSv/h or higher. Mars mission dose rates during interplanetary transit are approximately 1.8 mSv/day (20.8 nSv/s). Space radiation monitoring uses both Gy and Sv simultaneously — physical dose in Gy for material damage, effective dose in Sv for biological risk assessment — requiring constant conversion between these units.

This radiation converter supports all 22 dose rate units — the complete SI gray/second prefix series (EGy/s to aGy/s), rad/second, J/kg/second, W/kg, Sv/s, and rem/s — instantly and precisely, completely free.