## 2 Survey of Commercial Use of Radioactive Isotopes
### Mo
\({}^{103}\)Pd  
\({}^{103}\)Pd (T\({}_{1/2}\) = 16.99 days) radioactive sources supplied to the end medical treatments are enclosed in microseeds with low energy gamma emission that is rapidly absorbed in tissue, for instance, in ophthalmic plaque radiotherapy [13]. The implant with activity of 200-300 uCi [14] is typically positioned in the human body for 2-5 days. This isotope is usually produced through the \({}^{102}\)Pd(n,\(\gamma\))\({}^{103}\)Pd reaction in aluminum containers of 22 mm diameter and 46-50 mm length irradiated for 1-4 weeks. The typical yield of \({}^{103}\)Pd is \(\sim\)370 MBq per 100 mg of palladium [6]. The cost assessment of \({}^{103}\)Pd radioactive sources is complex because the medical treatments with this isotope are on a rising trend. A rough estimate of the commercial price could be USD 6000-12,500/seed [15]. \({}^{169}\)Yb  
\({}^{169}\)Yb (T\({}_{1/2}\) = 32.026 days) is a middle-energy brachytherapy decay gamma source; therefore, it is a very promising isotope to provide much higher absorbed dose in human organs compared to \({}^{192}\)Ir [16; 17]. This isotope is applied for cerebrospinal fluid treatments in the brain [4]. The \({}^{169}\)Yb radioactive source is produced in the \({}^{168}\)Yb(n,\(\gamma\))\({}^{169}\)Yb reaction with the irradiation of ytterbium oxide (Yb\({}_{2}\)O\({}_{3}\)) for 1 week. To increase the end yield of this isotope, the \({}^{168}\)Yb concentration in yttrium is enriched from the natural abundance of 0.13% up to 17.1% [6]. The irradiation of the target material of some 1.14 mg is carried out in a quartz vial of 14 mm diameter and 50 mm height for 1 week. The reference industrial product intensity achieved in such exposure is 1.6 TBq/g [6]. The high specific activity of the \({}^{169}\)Yb pieces enables the development of a much more efficient radioactive source as compared to ones loaded with an \({}^{192}\)Ir source. The cost of Yb\({}_{2}\)O\({}_{3}\) (82% \({}^{168}\)Yb) is currently USD \(\sim\)700/mg and the price of a \(\sim\)0.37 TBq (10 Ci) \({}^{169}\)Yb source is USD 1650-6000 [16]. \({}^{125}\)I  
The industrial production and utilization of \({}^{125}\)I (T\({}_{1/2}\) = 59.408 days) has many applications that become routine. \({}^{125}\)I is generated through the neutron irradiation of \({}^{124}\)Xe, formation of \({}^{125}\)Xe in the \({}^{124}\)Xe(n,\(\gamma\))\({}^{125}\)Xe reaction, and consequent decay of \({}^{125}\)Xe (T\({}_{1/2}\) = 16.9 h) into \({}^{125}\)I. For decades, the seeds for implantation filled with \({}^{125}\)I have been applied in nuclear radiation therapy, called brachytherapy, to treat in vitro malicious tumors. In such treatments, the distance between the seed and specific tumor location is usually short and enables exposure up to a preassigned dose that reduces unnecessary radiation damage of tissue in the vicinity. This isotope is also widely used in radioimmunoassays to detect hormones in tiny quantities [4]. The aluminum target capsule of 27 mm diameter and 200 mm length is filled with 0.4 g of the enriched \({}^{124}\)Xe and plugged [6]. The irradiation of the target for up to 1 week is applied to reach the reference specific activity of 6 \(\times\) 10\({}^{14}\) Bq/g. The market price of the \({}^{125}\)I sources can differ strongly depending on the specific activity and the volume of the source: USD 0.81-3.2/MBq (USD 30/mCi-USD 120/mCi) both for medical treatments and for industrial applications [18; 19; 20]. The world demand of \({}^{125}\)I is as high as 37 TBq/year (1000 Ci/year) [10].