"Robotic Surgeon Attacks Moving Tumors":

The surgeon, known as CyberKnife to its human colleagues, is a robot. Already deft at attacking brain tumors, CyberKnife received a computer software upgrade to more efficiently target constantly moving lung tumors.

CyberKnife was developed to pinpoint tumors and blast them from every angle with radiation, the goal being to confine the attack to cancerous tissue only.

If all goes well, after several treatments the tumor shrinks and disappears as if it were surgically removed, yet healthy tissues that might be damaged even by the nimble hands of a skilled human surgeon are spared.

Brain tumors provide a nice steady target, but a cancerous growth in the respiratory system, which can move up to 2 inches back and forth as a person breathes, present more of a challenge -- even to CyberKnife.

Now, Cihat Ozhasoglu of the University of Pittsburgh and colleagues have developed Synchrony, an add-on program for CyberKnife that allows it to follow the tumor to within a few hundredths of an inch as it moves.

As the CyberKnife trains its intense X-ray beam on the tumor, another weaker X-ray source takes real-time pictures of the patient's torso. Synchrony records the tumor's movements and tells CyberKnife when and where to direct the therapeutic beam.