A family physician in Tolland who was active in the Boy Scouts and provided physical examinations to boys involved in teen-aged sports was sentenced to 51 months in prison Tuesday after being caught with one of the biggest child porn collection ever found in Connecticut. Federal prosecutors said Dr. Carl Koplin's pornography collection, which he made available to others across the Internet, was large enough to fill 170 DVDs. When compiling his obscene collection from film made available by others, prosecutors said, Koplin once found a pornographic photograph of a boy he had treated for depression. Rather than report the photograph, as physicians are required, prosecutors said Koplin deleted the image. "This defendant's appalling collection of child pornography was one of the largest that we have seen here in Connecticut,"