RESUMO
This work presents the results obtained from the dosimetric properties of the new radiation detectors of KMgF3:Tbâ¯+â¯PTFE. The thermoluminescent material was obtained by microwave technique. The polycrystalline powder obtained was mixed with polytetrafluoroethylene resin powder in the ratio 2:3 to make dosimeters in pellet form. The thermoluminescent response of these new detectors presented a linear behavior, in the dose range between 1 and 1000â¯Gy 60Co gamma radiation, the repeatability test in the measurements, during ten cycles of heat treatment, irradiation and readouts, showed ±â¯3.7% DS, the stability test of thermoluminescent signal, during two months showed that the fading is practically null. For the results obtained, this new detector could be very useful for radiation dosimetry, in clinical applications.
Assuntos
Dosimetria Termoluminescente/métodos , Radioisótopos de Cobalto , Fluoretos , Raios gama , Humanos , Compostos de Magnésio , Politetrafluoretileno , Compostos de Potássio , Térbio , Dosimetria Termoluminescente/estatística & dados numéricosRESUMO
Radiolabelled somatostatin analogues have been used in diagnostic and therapeutic nuclear medicine to treat cancerous tumours. Lanreotide, a cyclic octapeptide, beta-naphthyl-peptide, with antiproliferative action on human small cell lung carcinoma was (188)Re labelled and characterised, and its biodistribution was studied in mice. Molecular modelling indicates that the lipophilic radiopharmaceutical might be an oxo-rhenium (V) penta-coordinated complex. The implanted human cervical tumour of epidermoid origin was positive for cytokeratins and Vimentin. Uptake of (188)Re-labelled peptide in the implanted tumour in athymic mice was 6.2+/-2.9% and was rapidly cleared via the hepatobiliary system. (188)Re-beta-naphthyl-peptide might be a potential therapeutic agent.
Assuntos
Antineoplásicos/farmacocinética , Peptídeos Cíclicos/farmacocinética , Compostos Radiofarmacêuticos/farmacocinética , Somatostatina/farmacocinética , Neoplasias do Colo do Útero/metabolismo , Animais , Feminino , Células HeLa , Humanos , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Nus , Ligação Proteica , Somatostatina/análogos & derivados , Distribuição TecidualRESUMO
The uptake of the rhenium-188 (188Re(V)-DMSA) complex of dimercaptosuccinic acid by cervical carcinoma cells in nude mice was evaluated. The pharmacokinetics and dosimetry calculations in normal rats were also evaluated. The images obtained in mice did not show significant accumulation in metabolic organs and the biodistribution studies showed that 3.52 +/- 0.76% of the injected activity per gram (n = 4) was taken up by the tumor. This percentage produces a cumulated activity of 35.63 +/- 8.40 MBq h and an equivalent dose per injected activity of 260 +/- 8.91 mSv/MBq. Pharmacokinetics and dosimetry of the 1887e(V)-DMSA complex indicate that this radiopharmaceutical could be evaluated in patients with soft tissue tumors, since the risk of radiation damage to the kidney or red bone marrow could not be an obstacle for its application in therapeutic nuclear medicine.
Assuntos
Compostos Organometálicos/farmacocinética , Radioisótopos/farmacocinética , Compostos Radiofarmacêuticos/farmacocinética , Rênio/farmacocinética , Succímero/farmacocinética , Neoplasias do Colo do Útero/metabolismo , Neoplasias do Colo do Útero/radioterapia , Animais , Feminino , Células HeLa , Humanos , Camundongos , Camundongos Nus , Compostos Organometálicos/administração & dosagem , Compostos Organometálicos/uso terapêutico , Doses de Radiação , Radioisótopos/administração & dosagem , Radioisótopos/uso terapêutico , Compostos Radiofarmacêuticos/administração & dosagem , Compostos Radiofarmacêuticos/uso terapêutico , Ratos , Ratos Wistar , Rênio/administração & dosagem , Rênio/uso terapêutico , Succímero/administração & dosagem , Succímero/uso terapêutico , Distribuição TecidualRESUMO
A direct labeling technique via EHDP for the preparation of 188Re-somatostatin analogue peptide beta-(2-naphthyl)-D-Ala-Cys-Tyr-D-Trp-Lys-Val-Cys-Thr-amide complex was developed. The influence of reaction conditions such as pH, temperature, weak ligand concentration and stannous chloride concentration were investigated. Methods of analysis were also established permitting identification of radiochemical impurities which may be present in the radiopharmaceutical solution. Results showed that under the procedure reported herein 188Re-peptide complex can be prepared with a radiochemical purity of 90% and a specific activity up to 1.8 GBq mg-1 without radiolytic degradation of the product.