Even after boogie-woogie/R&B pianist Dr. John hypnotized his cult following with a series of voodoo-riffic solo albums, the eccentric New Orleans performer never gave up his side career as a session player for the stars. He continued recording with the likes of B.B. King, Ringo Starr, Van Morrison, Spiritualized, G. Love and Special Sauce, Odetta, Jon Spencer Blues Explosion, Buddy Guy, Canned Heat, The Neville Brothers, Christina Aguilera and Beth Orton. Tonight, though, he’ll keep the spotlight firmly on himself when he headlines an 8 p.m. show at the Turner Hall Ballroom.