Comparison of Tangent Length and Distance to Center

Consider a circle with center O and a radius of r. A point P lies outside the circle such that the distance from P to O is greater than the radius, specifically, the distance PO = d where d > r. A tangent line is drawn from point P to the circle, meeting the circle at point T. Additionally, a segment connecting the center O to the tangent point T is drawn. Let’s define a segment from P to T as PT.

Using the Pythagorean theorem, we can establish a relationship among the segments: $$PT^2 = PO^2 - OT^2$$ where OT is equal to the radius r.

Given the following two quantitative comparisons:

Quantity A: The length of the tangent segment PT.

Quantity B: The length of the line segment from point P to the center O, minus the radius of the circle: $$PO - r$$

Based on these definitions, determine the relationship between Quantity A and Quantity B.