Can you post the whole question..Maybe to minimize damage? Remember The Folks at the Hospital uses MRI (which is pretty much a Radio wave hence has low Frequency/ Low energy ) to get a detailed picture of internal organs whilst X-Ray ( which is High Frequency/ High Energy) only shows you the bones or any hard structure).
So, the first reason is because of the Photo-electric effect, each time a High beam interact with a tissue, it ionized the elecctrons in those tissue thereby causing the production of Free Radical which in turn damages the DNA and wreak havoc... Also High energy photons have higher momentum hence higher speed this they are less likely to interact with matter thereby resulting in a weak image.
To sum it up, i guess Higher energy Photons or photon with lower wavelenght ought to penetrate the tissue better than Low Energy photons (photon with longer wavelenght) because of the difference in speed and momemtum.. However, the Low energy Photon (Higher wavelenght) interacts better with tissues.
It's a very general rule, used with ultrasound imaging, that the penetration depth is in the (200 x lamda) to (250 x lama) range. This is to say that as a wave penetrates in, it can oscillate back-and-forth about 200 to 250 times on average before it interacts in a way with the medium that it no longer propagates the same way. This could very well be the result of absorption. So for a longer wavelength, a greater distance can be covered per oscillation back-and-forth, resulting in a longer total distance traveled into tissue before it no longer penetrates in. A laser deals with light waves, as opposed to sound waves, so it is not an ideal analogy. But for a simple question at the level of the MCAT, this trinket of knowledge was applicable.
It's a very general rule, used with ultrasound imaging, that the penetration depth is in the (200 x lamda) to (250 x lama) range. This is to say that as a wave penetrates in, it can oscillate back-and-forth about 200 to 250 times on average before it interacts in a way with the medium that it no longer propagates the same way. This could very well be the result of absorption. So for a longer wavelength, a greater distance can be covered per oscillation back-and-forth, resulting in a longer total distance traveled into tissue before it no longer penetrates in. A laser deals with light waves, as opposed to sound waves, so it is not an ideal analogy. But for a simple question at the level of the MCAT, this trinket of knowledge was applicable.
oh, i can see why.. i am even more confused..The MCAT will not require that kind of knowledge and the question itself is a poor MCAT question.
The MCAT will not require that kind of knowledge and the question itself is a poor MCAT question.
They have that concept in questions within their released materials collection. It's actually a very good question in that it deals with a medical application of physics.
penetration depth is in the (200 x lamda) to (250 x lama) range.
