Medical ultrasound
A contrast medium for medical ultrasonography is a formulation of encapsulated gaseous microbubbles to increase echogenicity of blood, discovered by Dr Raymond Gramiak in 1968 and named contrast-enhanced ultrasound. This contrast medical imaging modality is clinically used throughout the world, in particular for echocardiography in the United States and for ultrasound radiology in Europe and Asia.
Radiosurgery
Stereotactic radiosurgery was first developed in 1949 by the Swedish neurosurgeon Lars Leksell to treat small targets in the brain that were not amenable to conventional surgery. The initial stereotactic instrument he conceived used probes and electrodes. The first attempt to supplant the electrodes with radiation was made in the early fifties, with x-rays. The principle of this instrument was to hit the intra-cranial target with narrow beams of radiation from multiple directions. The beam paths converge in the target volume, delivering a lethal cumulative dose of radiation there, while limiting the dose to the adjacent healthy tissue. Ten years later significant progress had been made, due in considerable measure to the contribution of the physicists Kurt Liden and Börje Larsson. At this time, stereotactic proton beams had replaced the x-rays. The heavy particle beam presented as an excellent replacement for the surgical knife, but the synchrocyclotron was too clumsy. Leksell proceeded to develop a practical, compact, precise and simple tool which could be handled by the surgeon himself. In 1968 this resulted in the Gamma Knife, which was installed at the Karolinska Institute and consisted of several cobalt-60 radioactive sources placed in a kind of helmet with central channels for irradiation with gamma rays. This prototype was designed to produce slit-like radiation lesions for functional neurosurgical procedures to treat pain, movement disorders, or behavioral disorders that did not respond to conventional treatment. The success of this first unit led to the construction of a second device, containing 179 cobalt-60 sources. This second Gamma Knife unit was designed to produce spherical lesions to treat brain tumors and intracranial arteriovenous malformations (AVMs). In the 1980s the third and fourth units (with 201 cobalt-60 sources) were installed in Buenos Aires, Argentina, and Sheffield, England. The fifth Gamma Knife was installed at the University of Pittsburgh Medical Center in Pittsburgh in 1987.