What types of light can safely pass through the human body?

[Logs]

What types of light are able to pass through the human body without causing damage to tissue or individual cells? Are there any truly safe alternatives to x-rays that could allow doctors to see internal body parts but not cause damage from extended exposure?

 

[Ygggdrasil]

MRI uses radio-frequency light to image internal structures within the body.

 

[davenn]

MRI uses radio-frequency light to image internal structures within the body.

you should really use the word light in there ... it could lead to added confusion that the OP seems to already have about definitions

MRI's use Magnetic fields and Radio waves ( EM fields)

What types of light are able to pass through the human body without causing damage to tissue or individual cells?

by the definition of light, Infra red through visible to Ultra Violet part of the EM spectrum, there isn't one that will pass through the body

Dave

 

[Ygggdrasil]

In physics, the term light sometimes refers to electromagnetic radiation of any wavelength, whether visible or not.[5][6] In this sense, gamma rays, X-rays, microwaves and radio waves are also light.

https://en.m.wikipedia.org/wiki/Light

 

[Andy Resnick]

What types of light are able to pass through the human body without causing damage to tissue or individual cells? Are there any truly safe alternatives to x-rays that could allow doctors to see internal body parts but not cause damage from extended exposure?

This is a long-standing problem not just in medicine but all biomedical research that uses imaging methods. In general, long-wavelength light (millimeter-wave and longer) will pass through biological tissue quite readily- cell phone and radio signals are clear examples. The trade-off is that the resolving power of long-wavelength radiation is very poor in comparison with visible light.

Consequently, other approaches are used. MRI is sort-of one; it doesn't image by scattering light off objects but rather selectively excites hydrogen (most commonly found in water) and the emitted radiation is detected. Another approach is to refine CT imaging to use lower dosages. A third is optical coherence tomography, conceptually similar to ultrasound in that reflections from discontinuities are imaged, but the technology is radically different.

In research, there is a wealth of approaches, typically involving thin sections of tissue- not appropriate for medical applications.