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In this paper the use of a Genetic Algorithm to solve a constrained vehicle routing problem is explored. The problem is two-dimensional with obstacles represented as ellipses of uncertainty surrounding each obstacle point. A route is defined as a series of points through which the vehicle sequentially travels from the starting point to the ending point. The physical constraints oftotal route length and maximum turn angle are included and appear in the fitness function. In order to be valid, a route must go from start to finish without violating any constraint. The effects that different mutation rates and population sizes have on the algorithm's computation speed and ability to find a high quality route are also explored. Finally, possible applications ofthis algorithm to the problem ofroute planning for cruise missiles are discussed.

We evaluated 4 patients with surgically proved retroperitoneal fibrosis by computerized tomography and ultrasound. Retroperitoneal fibrosis was diagnosed correctly in all 4 patients by computerized tomography but was detected by ultrasound in only 1. On computerized tomography, retroperitoneal fibrosis demonstrated a characteristic soft tissue mass enveloping the abdominal aorta, inferior vena cava and ureters. Computerized tomography was capable of detecting the abnormality with greater reliability than ultrasound, and was far superior in delineating the extent of the process and its relation to adjacent abdominal structures. Computerized tomography is the method of choice in the preoperative evaluation evaluation of retroperitoneal fibrosis. It also is anticipated that computerized tomography will prove equally useful in the postoperative followup of this disease.

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