**2.1.3 Therapeutic radiopharmaceuticals**

In the area of therapeutic nuclear medicine, there are lots of applications of different kinds of radiopharmaceuticals. For example, sodium of 32P-phosphate is an FDA-approved radiopharmaceutical indicated for treatment of polycythemia vera, chronic myelocytic leukemia, chronic lymphocytic leukemia, and for palliation of metastatic bone pain. Chromic 32P-phosphate is suspension of 32P used for intracavity installation for treatment of peritoneal or pleural effusions caused by metastatic disease. Phosphorus-32 decays by betaemission with a half life of 14.3 days. The major toxicity noted is significant marrow suppression in approximately one third of patients receiving this radiopharmaceutical.

Iodine-131 (131I) is the important therapeutic radiopharmaceutical, as a capsule or a solution for oral administration, which decays by beta- emission with subsequent gamma emission of 364 keV (82%) and has a life time of 8 days. Iodine-125 (125I) delivers a higher radiation dose to the patient due to the half life of 60 days and 125I seeds have been used in the therapy of solid tumors.

In skeleton nuclear medicine, some radionuclides are chosen as an effective way for treating the bone pain caused by the bone metastases. 89Sr-chloride (Metastron) has been approved by the FDA for relief of bone pain in cases of painful skeletal metastases. The compound behaves biologically like calcium and localizes in hydroxyapatite crystal by ion exchange. Strontium uptake occurs preferentially at sites of active osteogenesis. This allows primary bone tumors and areas of metastatic involvement to accumulate significantly higher concentration of strontium than surrounding normal bone. 89Sr decays by beta- emission with a half life of 50.6 days.

Another two radiotherapeutic agents, 186Re-HEDP and 153Sm-EDTMP are also used in the area. 186Re decays by beta- and gamma emission with a half life of 90.6 hr and 153Sm decays by beta- emission and has a half life of 46.3 hr. Both of these beta-emitting radionuclides are complex with bone-seeking ligands, which localize by chemisorption. The duration of response is 1-12 months. The main toxicity of these radiotherapeutics is mild transient bone marrow suppression.

9 9 18.0009380(6) 109.7min

18F-2-fluoro-2-deoxy-d-glucose (18F-FDG), 18F sodium fluoride (18F-NaF) and 11C-choline PET imaging is also called bone metabolic imaging. Here we will mention 18F-FDG and 18F-NaF imaging. 18F-FDG (2-fluoro-2-deoxy-d-glucose) is a glucose analogue with a fluorine atom replacing a hydroxyl group in the C-2 position of d-glucose. 18F exchanges with the hydroxyl (OH) ion in the hydroxyapatite. Although the mechanisms are not completely understood, the principal of bone imaging is fairly basic. Radiopharmaceuticals used in bone imaging can localize in soft tissues, demonstrating not only calcification but also

In the area of therapeutic nuclear medicine, there are lots of applications of different kinds of radiopharmaceuticals. For example, sodium of 32P-phosphate is an FDA-approved radiopharmaceutical indicated for treatment of polycythemia vera, chronic myelocytic leukemia, chronic lymphocytic leukemia, and for palliation of metastatic bone pain. Chromic 32P-phosphate is suspension of 32P used for intracavity installation for treatment of peritoneal or pleural effusions caused by metastatic disease. Phosphorus-32 decays by betaemission with a half life of 14.3 days. The major toxicity noted is significant marrow suppression in approximately one third of patients receiving this radiopharmaceutical. Iodine-131 (131I) is the important therapeutic radiopharmaceutical, as a capsule or a solution for oral administration, which decays by beta- emission with subsequent gamma emission of 364 keV (82%) and has a life time of 8 days. Iodine-125 (125I) delivers a higher radiation dose to the patient due to the half life of 60 days and 125I seeds have been used in the therapy

In skeleton nuclear medicine, some radionuclides are chosen as an effective way for treating the bone pain caused by the bone metastases. 89Sr-chloride (Metastron) has been approved by the FDA for relief of bone pain in cases of painful skeletal metastases. The compound behaves biologically like calcium and localizes in hydroxyapatite crystal by ion exchange. Strontium uptake occurs preferentially at sites of active osteogenesis. This allows primary bone tumors and areas of metastatic involvement to accumulate significantly higher concentration of strontium than surrounding normal bone. 89Sr decays by beta- emission

Another two radiotherapeutic agents, 186Re-HEDP and 153Sm-EDTMP are also used in the area. 186Re decays by beta- and gamma emission with a half life of 90.6 hr and 153Sm decays by beta- emission and has a half life of 46.3 hr. Both of these beta-emitting radionuclides are complex with bone-seeking ligands, which localize by chemisorption. The duration of response is 1-12 months. The main toxicity of these radiotherapeutics is mild transient bone

**mode(s)** 

Positron

**excitation energy isotope(s)** 

0.6335 MeV β-

6 5 11.011433(10) 20.33 min β+ 11B

**Daughter** 

18O

**Nuclide symbol Z(p) N(n) isotopic mass (u) half-life Decay** 

0.96 MeV Table 2. The nuclear physics characteristics of positron radionuclide 18F, 11C

Fluorine-18 18F

Carbon-11 11C

of solid tumors.

with a half life of 50.6 days.

marrow suppression.

inflammation, trauma, and tumor.

**2.1.3 Therapeutic radiopharmaceuticals** 
