A voucher is a bond of the redeemable transaction type which is worth a certain monetary value and which may be spent only for specific reasons or on specific goods.
In 1985 a robot, the Unimation Puma 200, was used to place a needle for a brain biopsy using CT guidance. In 1992, the PROBOT, developed at Imperial College London, was used to perform prostatic surgery by Dr. Senthil Nathan at Guy's and St Thomas' Hospital, London. This was the first pure robotic surgery in the world.
One of the most important orthopedic surgical advances of this century, knee replacement was first performed in 1968. Improvements in surgical materials and techniques since then have greatly increased the procedures effectiveness.