As mentioned in the previous section geophysical imaging and medical imaging are both noninvasive approaches. These methods share key attributes and explore the same physics and mathematics, and suffer from similar limitations. We use the general knowledge that most everyone has about medical imaging to introduce the key attributes of non invasive imaging.
In medical imaging an instrument is used to answer a question about what is happening inside a body. Different instruments are used (X ray, ultrasound, MRI), and data is obtained from that instrument. The instrument which is used depends on the question which is asked: to get an answer to question on teeth one uses an X-ray, to get an answer on questions about the progress of pregnancies one uses ultrasound. The instrument creates an image, which is interpreted by a specialist to answer the original question.
This description provides us with the key attributes of non invasive imaging which apply equally to geophysical and medical imaging:
Keeping these attributes in mind should help the non geophysicist to develop an initial understanding of what geophysical imaging is. Of course, there are several questions which are raised by this description of key attributes. Specifically, these are