Fig. 1

Bone scintigraphy images of three prostate cancer patients at different stages. a: An example patient without bone metastases; free PSA: 2.53 ng/ml, total PSA:17.54 ng/ml, free/total PSA ratio: 0.144, ALP: 43 U/L, b: An example patient with numerous metastases; free PSA: 3.11 ng/ml, total PSA:18.30 ng/ml, free/total PSA ratio: 0.169, ALP: 114 U/L. C: An example patient with multiple metastases; free PSA: 12.90 ng/ml, total PSA:121.20 ng/ml, free/total PSA ratio: 0.106, ALP: 109 U/L