Let E be a Banach space, 1 < p < 2 and 1/p + 1/p' = 1. We investigate the relationship between yp-Radonifying operators from Lv,(fLit) into E and other well-known operator ideals. We show that E is of stable type p and of SQp type if and only if every dual p-nuclear operator from Lp,(~, p) into E is 7p-Radonifying; and E is of stable type p and of Sp type if and only if every dual quasi-p-nuclear operator from Lp,(fL It) into E is 7p-Radonifying. In the case where E is of stable type p, we also show that E is of SQv type if and only if every 7p-Radonifying operator from Lp,(Q, it) into E is p-summing; and E is of Qp type if and only if every 7p-Radonifying operator from Lp,(~, It) into E is p-nuclear. These results extend the works of [5,10,20], and give the solutions to problems of [5].