True regarding permissible radiation
**Core Concept**
The permissible radiation limit is a critical concept in radiation protection, referring to the maximum amount of ionizing radiation that can be safely absorbed by the human body without causing harm. This limit is essential in medical imaging, nuclear medicine, and radiation therapy to prevent radiation-induced injuries and long-term health effects.
**Why the Correct Answer is Right**
The permissible radiation limit is based on the concept of the "Sievert" (Sv), which is a measure of the biological effect of radiation. The average annual radiation exposure limit for workers in the nuclear industry is 20 millisieverts (mSv) per year, while the limit for the general public is 1 mSv per year. This limit is designed to minimize the risk of radiation-induced cancer and other health effects.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because it does not specify the correct unit of measurement for radiation exposure.
* **Option B:** This option is incorrect because it is too high, exceeding the recommended annual limit for workers in the nuclear industry.
* **Option C:** This option is incorrect because it is too low, not accounting for the varying levels of radiation exposure in different medical and industrial settings.
**Clinical Pearl / High-Yield Fact**
A key point to remember is that radiation exposure should be kept as low as reasonably achievable (ALARA) to minimize the risk of radiation-induced injuries and long-term health effects.
**Correct Answer:** D.