Specialized Fiber Collimators

Asynchrony of conduction within the canine specialized Purkinje fiber system.

Asynchrony of conduction may prove to be an important mechanism for reentrant arrhythmias. The purpose of these experiments was to explore asynchronous conduction in the distal branches of the canine Purkinje system. Microelectrodes were placed in Purkinje bundle preparations resembling a T configuration, thereby permitting assessment of differential conduction times induced by premature beats ...

Electrophysiological evidence for specialized fiber types in rabbit atrium.

PAES DE CARVALHO, ANTONIO, WALMOR CARLOS DE MELLO AND BRIAN F. HOFFMAN. Electrophysiological evidence for specialized Jiber types in rabbit atrium. Am. J. Physiol. I g6(3):483-488 I g59.-Intracellular microelectrodes have been used to study the site of origin and direction of spread of activity in the rabbit atrium. In this study a number of fiber groups have been found which possess specialize...

Mini and Micro Multileaf Collimators

Multiple arc or multiple field convergent beam irradiation techniques have been used extensively for stereotactic radiosurgery (SRS) or radiotherapy (SRT) of small lesions. A major problem is that dose distributions produced by employing rectangular or circular collimators are of simple convex shape and therefore do not allow conformal treatment of irregularly shaped lesions. The use of multipl...

Algorithms for Sequencing Multileaf Collimators

Robotic radiosurgery with noncylindrical collimators.

In radiosurgery, a moving beam of radiation acts as an ablative surgical instrument. Conventional systems for radiosurgery use a cylindrical radiation beam of fixed cross section. The radiation source can be moved only along simple, standardized paths. A new radiosurgical system based on a six-degree-of-freedom robotic arm has been developed to overcome limitations of conventional systems. We a...