By the numbers

Ratings . . .

Last Friday’s “Dateline” (the Van Ryn/Cerak mistaken identity case) snared 10.5 mil lion viewers – NBC’s biggest timeslot viewership numbers since June ’07.

And Part One of “The Cap ture of the Green River Killer” (Tom Cav anagh, Sharon Lawrence) became the most-watched show in Lifetime Movie Network history Sunday, av eraging over 2 million view ers. It also set records in sev eral key demos (including persons 25-54, women 25-54). Part Two aired last night.

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Don Imus kicks off his 19th annual “Radiothon” May 8 on WABC (770 AM) to raise money for The To morrows Children’s Fun, CJ Foundation for SIDS and the Imus Ranch for Kids with Can cer. The radiothon will run from 6 a.m. through the next morning.

Imus has helped raise more than $40,000,000 over the history of the radiothon.

A little farther up the dial, and over on the FM side, Q104’s Jim Kerr welcomes Ace Frehley (today) and Jackie Martling (Thursday) on his morning show.

Last, but not least:

* The Alvin Ailey Ameri can Dance Theater, cele brating its 50th anniversary, appears on tonight’s “Danc ing with the Stars” accom panied by gospel singers.

* Minka Kelly (“Friday Night Lights”) at Tenjune last Friday night. Her show’s fate remains uncertain.

* Casey Patterson has been named senior VP, event production/ talent develop ment, at Spike TV and TV Land.

* Ruby rings in: Congrats to ABC’s Cathie Levine and husband Josh Isay on the ar rival of Ruby Belle.