Experimental setup for light-to-heat NIR conversion measurements of gold nano-particles\u2019 solutions

In recent years, there is a constantly increasing interest in the application of nanoparticles for cancer diagnosis and cancer therapy. In this respect, the most promising nano-objects at present are the gold nanoparticles. A very convenient and powerful property of these objects is their ability to increase their temperature under electro-magnetic irradiation with certain wavelength. In our research we have directed our efforts toward particular nano-objects specifically sensitive to electromagnetic radiation in the near-infrared region (NIR). In order to study the photothermic properties of the solutions of gold nanoparticles in the NIR we constructed a specific electronic setup consisting of a laser system with interchangeable laser diodes with different wavelength NIR light, a thermally-insulated cuvette-holder compartment with temperature measuring probes and a NIR spectrometer to control the stimulated fluorescence emission of the nanoparticles\u2019 solutions. The temperature measurement compartment with the thermal-insulated cuvette holder was designed to maintain the solutions\u2019 temperature at a fixed value right before the moment of laser irradiation. To maintain the measurement setup at a fixed temperature before the irradiation we used a thermal stabilized system based on two Peltier cells with electronic temperature control. The temperatures of the ambient air and the temperature of the cuvette walls were continuously measured in order to make corrections about the temperature dissipation during the irradiation

Assessment of dose increase after administration of radiopharmaceuticals prepared with cyclotron-produced 99mTc

Technetium-99m (99mTc) is currently available from 99Mo/99mTc generators as the \u3b2-decay product of 99Mo (T\ubd=66 h). Nowadays, 99Mo is mostly obtained as a fission product in nuclear reactors by neutron-induced reactions on highly enriched uranium. Alternative production routes, such as direct production of 99mTc via 100Mo(p,2n)99mTc reaction using medical cyclotrons has the potential to be both reliable and relatively costeffective. However, results showed that the extracted 99mTc from the proton-bombarded 100Mo-enriched target contains small quantities of several Tc radioisotopes (93mTc, 93Tc, 94Tc, 94mTc, 95Tc, 95mTc, 96Tc and 97mTc). The aim of this work was to estimate the dose increase (DI) due to the contribution of Tc radioisotopes generated as impurities, after the intravenous injection of four radiopharmaceuticals prepared with cyclotronproduced 99mTc (CP-99mTc) using 99.05% 100Mo-enriched metallic targets. Four 99mTc radiopharmaceuticals (pertechnetate, sestamibi (MIBI), hexamethylpropylene- amine oxime (HMPAO) and disodium etidronate (HEDP)), were considered in this study. The biokinetic models reported by the International Commission on Radiological Protection (ICRP) for each radiopharmaceutical were used to define the main source organs and to calculate the number of disintegrations per MBq that occurred in each source organ (Nsource) for each Tc radioisotope present in the CP-99mTc solution. Then, target organ equivalent doses and effective dose were calculated for each Tc radioisotope with the OLINDA/EXM software versions 1.1 and 2.0, using the calculated Nsource values and the adult male phantom as program inputs. Total effective dose produced by all Tc isotopes impurities present in the CP-99mTc solution was calculated using the fraction of total activity corresponding to each radioisotope generated by the bombardment of 100Mo-enriched (99.05%) metallic target. Finally, the effective obtained dose was compared with the effective dose delivered by the generator-produced 99mTc. The total effective dose increases of CP-99mTc radiopharmaceuticals, calculated with both versions of the OLINDA software, remained within the 10% limit in all cases, from 6 up to 12 hours after end of bombardment (EOB). The Tc radioisotopes with the highest concentration in the CP-99mTc solution at EOB are 94mTc and 93mTc. However, their contribution to DI 6 hours after EOB is minimal, due to their short half-lives. 96Tc is the radioisotope with the largest contribution to the effective DI, followed by 95Tc and 94Tc, although their concentration in the CP-99mTc solution is 5 times less than 94mTc and 93mTc at the EOB. This is due to the types of their emissions and relatively long half-lives. The increase in the radiation dose caused by the other Tc radioisotopes contained in produced CP-99mTc, as described here, is quite low. Although the concentrations of the 94Tc and 95Tc radioisotopes in the CP-99mTc solution exceed the limits established by the European Pharmacopoeia, CP-99mTc radiopharmaceuticals could be used in routine nuclear medicine diagnostic studies if administered from 6 to 12 hours after the EOB; thus, maintaining the effective DI within the 10% limit