Preliminary imaging procedure using the gold needle inserted into an onion. Note the image attenuation area around the needle. In these experiments the length of the inserted portion corresponded to the length of the image attenuation effect. The width of the defect was much larger than the width of the gold needle.
Moncayo et al. BMC Medical Imaging 2007 7:4 doi:10.1186/1471-2342-7-4