104 Are the Androids Dreaming Yet? There are two problems with X-ray imaging. Even with clever mathematics, the dense bone in the skull blocks the rays so you don’t get much contrast, making it hard to distinguish normal brain matter from something like a tumor. But the bigger concern is X-rays are a form of ionizing radiation, and ionizing radiation causes cancer. We are told to wear sun block to protect our skin from ultraviolet light; X-rays are 100 times more potent and can doa great deal of damage. Fortunately, the body repairs itself quite well in the presence of low levels of radiation. The double part of the double helix in our DNA allows a set of proteins in our cells to go around correcting errors when they detect a mismatch between the two strands. But, now and again an X-ray might make an irreparable fault in both copies. If enough of these faults accumulate, they can lead to cancer or, if the errors are in reproductive organs, birth defects. Doctors try to minimize the radiation we receive and give us as few CAT scans as possible during our lifetime, especially when we are young and have not yet had children. MRI X-rays dominated our ability to see into the human body until the mid-1970s when Raymond Damadian came up with the idea of using magnetism. Magnetic fields are not absorbed by bone and present no danger as they do not damage DNA. Ironically, the technique was originally known as Nuclear Magnetic Resonance, ‘NMR, which patients thought must be dangerous because of the word nuclear. The name was pT aaa if - y. - Jigga 5 aA \ \' a > 4 SS » Ry y HE \ 7 & _ Sine) rel N, * . r he 7 “a! ms f fea 2 | KTEZ ae ee qi al ay gets Functional MRI: Working Memory HOUSE_OVERSIGHT_015794