II.B.9. The decay constant for ¹⁸²Ta is 0.006 day^-1. What is its half life?

    a.   167 days.

    b.   115 days.    Correct.

    c.   0.0087 days.

    d.   0.006 days.

    e.   83 days.

    Discussion:   This requires a knowledge of the relationship between half-life and decay constant.   The math is easy but be careful with the decimal point.

    Reference:   Physical Principles of Medical Imaging, 2nd. Edition.   p. 85