Let \gamma_{1}, \gamma_{2}, \gamma_{3} be three circles with radii 3,4,9, respectively, such that \gamma_{1} and \gamma_{2} are externally tangent at C, and \gamma_{3} is internally tangent to \gamma_{1} and \gamma_{2} at A and B, respectively. Suppose the tangents to \gamma_{3} at A and B intersect at X. The line through X and C intersect \gamma_{3} at two points, P and Q. Compute P Q.