مؤسسة الشرق الأوسط للنشر العلمي
عادةً ما يتم الرد في غضون خمس دقائق
The recent unexpected closure of the Chalk River, Canada, reactor and the high flux reactor, The Netherlands, at the same period in 2010 as the main supplier of radionuclides in the world lead to major interruption in the supply of the most important radionuclide used in medicine nowadays, Molybdenum-99 (Mo-99). In addition to this period, another shortage of Mo-99 supply occurred during the last decade resulting from maintenance of some other smaller reactors. Mo-99 is the source (parent) of Technetium-99m (Tc-99m) (daughter) which is used in about 80% of all nuclear medicine imaging procedures. Tc-99m has many characteristics which make it the preferable radionuclide in clinical applications. For example, it can be produced easily from a small onsite generator containing Mo-99 in a few minutes. Then, the decay of the source’s activity (half-life) is approximately 6 hours, which is a short time and suitable for most diagnostic examinations, resulting in low patient dose and good image quality. In addition, decay of product is an important factor for imaging; hence Tc-99m producing pure gamma radiation at 140 kilo electron Volts (keV) is an ideal radionuclide. However, when this crisis occurred in 2010, some alternative radionuclides were applied in most of the nuclear medicine procedures, such as Rubidium-82 (Rb-82) and Thalium-201 (Tl- 201). The difference in the physical and biological properties of these alternatives must be considered and studied, then compared with Tc-99m properties for accurate images and lower patient doses. For example, with the myocardial perfusion test, Rb-82 characteristics are more useful than Tl-201 for better imaging results, a shorter physical half-life at 78 seconds and 73 hours respectively, lower radiation dose to the patient and an onsite generator for production. However, despite these advantages of Rb-82, Tl-201 is the most available technique nowadays and can be applied by classical imaging methods (planar) without a computer to process the image. Then, the cost of installation of an Rb-82 facility is high. In addition, imaging techniques are another reason to be considered because Rb-82 has a detection process of positron emissions, while Tl-201 has the detection of single gamma photon emission (the same as Tc-99m) and each technique has its effect on the imaging process. Recently, there is another trend to produce Tc-99m by accelerators instead of reactors to cover any expected shortage. Tc-99m production by accelerator is in the development level and is not yet the perfect way for Tc-99m supply. Hence, as new reactors in the world are planned, still most rely on those reactors’ production of the isotopes and supply. On the other hand, alteration of work schedules (extended work time) might be a short-term solution in this crisis of supply shortage. However, the challenge that faces this idea is connected with the decay of the Mo-99 depending upon the half-life.