A bone scan, specifically a DEXA (dual-energy X-ray absorptiometry) scan used to measure bone density, exposes a person to a very low dose of radiation—much lower than many common sources of radiation in daily life. To understand how many cigarettes would equal the radiation from a bone scan, it’s important to compare the radiation dose from the scan to the radiation dose associated with smoking.
A typical DEXA bone density scan exposes a person to about 1 to 13 microsieverts (µSv) of radiation, depending on the specific machine and protocol. This is generally less than the radiation from a standard chest X-ray and is often compared to the amount of natural background radiation a person receives in a few hours to a day. For example, being outdoors in sunlight for about a day exposes you to roughly the same radiation dose as a DEXA scan.
On the other hand, smoking cigarettes exposes the body to radiation primarily through radioactive elements like polonium-210 and lead-210 found in tobacco smoke. The radiation dose from smoking varies widely depending on the number of cigarettes smoked and the duration of smoking. Estimates suggest that smoking one pack of cigarettes (20 cigarettes) per day for a year can expose the lungs to about 160 millisieverts (mSv) of radiation cumulatively, which is a much higher dose than a single medical scan.
To break it down to a per-cigarette basis, the radiation dose from one cigarette is roughly estimated to be around 0.008 mSv (8 microsieverts). This means:
– A single cigarette delivers about 8 µSv of radiation.
– A DEXA bone scan delivers roughly 1 to 13 µSv of radiation.
From this, you can see that the radiation from one bone scan is approximately equivalent to the radiation from smoking **about one to two cigarettes**. The exact number depends on the scan’s radiation dose and the cigarette’s radiation content, but it’s generally in this range.
It’s important to note that the radiation from smoking is delivered directly to lung tissue repeatedly over time, contributing to cumulative damage and increased cancer risk. In contrast, the radiation from a bone scan is a one-time, very low dose exposure used for diagnostic purposes, with minimal risk when medically justified.
In perspective, the radiation from a bone scan is very low and comparable to everyday natural exposures or smoking a couple of cigarettes. This comparison helps put the scan’s radiation dose into context, showing that while any radiation exposure carries some risk, the amount from a bone scan is minimal and generally safe when performed as needed.
