## 2 Survey of Commercial Use of Radioactive Isotopes
### \({}^{153}\)Sm  
Palliative care can include effective symptom and pain relief with such isotopes as \({}^{153}\)Sm [4] with a T\({}_{1/2}\) = 46.27 h. The importance of this isotope is increasing in radiological cancer treatment. The routine production of this isotope is carried out in small research reactors by means of the neutron irradiation of samarium enriched in \({}^{152}\)Sm up to 100%: \({}^{152}\)Sm(n,\(\gamma\))\({}^{153}\)Sm [6]. The target quartz capsule of 8 mm diameter and 50 mm length for irradiation is filled with 1 mg of the Sm\({}_{2}\)O\({}_{3}\) and it is irradiated for 2-3 days. The specific activity achieved at the end of the irradiation is 1.5 \(\times\) 10\({}^{13}\) Bq/g [6]. \({}^{153}\)Sm is administered in a dose of 37 MBq/kg (1 mCi/kg) delivered through intravenous injection during the 1 min treatment that leads to estimated pain relief duration from 4 up to 40 weeks [29]. The reference specific activity of approximately 1 \(\times\) 10\({}^{12}\) Bq/g is already sufficient for its practical use in medical treatments [30]. The typical prescribed dose for one medical treatment is 37 MBq/kg; therefore, a patient weighing 70 kg requires 2590 Bq (70 mCi), and the whole procedure could be repeated up to four times in one year, resulting in ~115 TBq/year (3100 Ci/year) only in the USA [10], and roughly doubled in the world. An estimated medical treatment with the \({}^{153}\)Sm source is USD ~12,000 per patient and the price for the \({}^{153}\)Sm isotope varies from USD ~378,380-729,730/TBq (USD 14,000-27,000/Ci) [31; 32; 33] depending on the supplier. \({}^{177}\)Lu (T\({}_{1/2}\) = 6.734 days) is a somewhat short-lived isotope with enormous applications in the medical industry [4], and its radioactive properties make it a powerful tool for the direct treatment of certain cancers. The production of \({}^{177}\)Lu is performed by direct neutron irradiation of enriched \({}^{176}\)Lu through neutron capture: \({}^{176}\)Lu(n,\(\gamma\))\({}^{177}\)Lu. The target material, Lu\({}_{2}\)O\({}_{3}\), in the amount of 10 mg sealed in a quartz ampule of 8 mm diameter and 50 mm length and irradiated for 1 week can reach a specific reference activity of 2 \(\times\) 10\({}^{12}\) Bq/g [6]. The lutetium-176 with a natural abundance of 2.59% is usually used enriched up to ~70%. The price for the enriched \({}^{176}\)Lu can reach USD 220/mg [34; 35] and the price for the \({}^{176}\)Lu radioactive source is estimated to be USD 1-2.2 M/TBq (USD 38,000-80,000/Ci) [36; 37]. \({}^{186}\)Re (T\({}_{1/2}\) = 3.718 days) is used for bone pain palliative care [4; 10]. This isotope is fabricated through neutron irradiation of \({}^{185}\)Re in the fission reactors: \({}^{185}\)Re(n,\(\gamma\))\({}^{186}\)Re. The target material, 1-12 mg of Re enriched above 94% of \({}^{185}\)Re, is enclosed in quartz capsules of 9 mm diameter and 50 mm length and it is irradiated for 7-10 days [6]. The reference specific activity achieved at the end of the irradiation is 3.7 \(\times\) 10\({}^{13}\) Bq/g [10]. The estimated annual demand of \({}^{186}\)Re in the USA is 148 TBq/year (4000 Ci/year) and it might be twice as high worldwide [10]. The dose of 1.5 GBq (40 mCi) is usually prescribed up to four times per year. Rhenium is the rarest stable nonradioactive element, and the price for the target material, ~97.4% pure \({}^{185}\)Re, is, accordingly, USD ~9500/g [35]. The \({}^{186}\)Re radioactive source price is found to be USD ~12,000/5.5 GBq, that is, USD ~2.2 M/TBq (USD 81,000/Ci) [38]. \({}^{204}\)Tl (T\({}_{1/2}\) = 3.78 years) is applied in the industry for measurement of dust levels in technical filters and for calibration and assessment of the thicknesses of plastic, metal, rubber, and paper sheets. This isotope is typically produced in fission reactors through the neutron irradiation of the target material \({}^{203}\)Tl(n,\(\gamma\))\({}^{204}\)Tl. Metal thulium in the amount of 1 g is sealed in aluminum cans of 22 mm diameter and 50 mm length.