ABSTRACT
Background: In CT systems, the machine utilizes a bowtie filter to shape the X -ray beam and remove lower energy photons. The shape of this bowtie filter is complicated and its geometry is often not available in detail. These renders the CT dose index [CTDI] to have different values in measurement versus Monte Carlo simulation studies and other analytical calculations especially in dosimetry of internal organs. In existing literature, the bowtie filter shape is extracted by using expensive sensors
Materials and Methods: In the present work, the shape of the bowtie filter of the Biograph 6 PET/CT was derived by using Thermolumenecence dosimeters [TLDs]. Subsequently, to evaluate the accuracy of the body bowtie filter shape as generated by TLDs, Monte Carlo simulation of CT was performed. 16 X-ray sources in various angles were used within the Monte Carlo code [MCNP-4C] to simulate the CT section of the PET -CT Biograph 6 system and to calculate dose
Results: The relative difference between simulated and measured CTDI value for the PET/CT Siemens Biograph 6 at 80, 110 and 130 kVp were 4.2, 2.9 and 2.3%, respectively
Conclusion: In this study, we demonstrate that it is possible to calculate the bowtie filter shape by using an inexpensive TLD method. The results showed that it is possible to determine the shape of the bowtie filter in PET/CT using TLDs with acceptable accuracy?
ABSTRACT
Too much fat in the diet can cause insulin resistance. This study was conducted to provide a suitable experimental model of type 2 diabetes and to compare the potency of olive and rump oils in the induction of insulin resistance. The study was done in three phases, each with 15 male Sprague dawley rats. The control, olive oil, and rump oil, groups were fed the commercial diet, and diets supplemented by 31% olive or rump oils for three weeks, respectively [first stage], and then diabetes was induced by IP injection of 35 mg/kg STZ [stages 2 and 3]. The oral glucose tolerance test [OGTT] showed glucose intolerance in both oil groups, compared to the control group [p<0.05], in stage 1, but increases in blood glucose levels were higher in the olive oil group in the second stage. TC and LDL-C levels increased by both the oils, especially olive oil. Insulin level was higher in the rump oil groups, especially after diabetes induction. Insulin sensitivity, as shown by the insulin tolerance test [ITT] and HOMA-IR, were decreased by both oils, especially rump oil. Although both oils had significant effects on metabolism, olive oil use was accompanied by more dyslipidemia, whereas rump oil increased insulin resistance more effectively. It seems that rump oil may be a more appropriate model for studies investigating disorders of carbohydrate metabolism of type 2 diabetes and olive oil, for induction of dyslipidemia and probably the metabolic syndrome
ABSTRACT
[18F]-6-thia-14-fluoro-heptadecanoic acid 3b, a free fatty acid, has been used in myocardial PET imaging. In order to establish an automated synthesis module for routine production in the country, a study performed for optimization of the production conditions as well as making modifications. [18F] Benzyl-14-Fluoro-6-thia-heptadecanoate 2b was prepared in no-carrier-added [n.c.a] form from C in Benzyl-14-tosyloxy-6-thia-heptadecanoate 1 in one step at 90 Kryptofix2.2.2/[18F] and acetonitrile as the solvent followed by Silica column chromatography. The radiolabeled ester 2 was then hydrolyzed to yield [18F]-6-thia-14-fluoro-heptadecanoic 3b. The final solution was concentrated using C18 SPE system and administered to normal rats for biodistribution as well as co-incidence imaging studies. The synthesis took 15 min with overall radiochemical yield of 15-25% [EOS] and chemical-radiochemical purity more than 94%. Automation was performed using a two-pot synthesis. The best imaging time was shown to be 140-180 minutes post injection. Using this procedure a fast, reliable, automated synthesis for the cordial PET tracer, i.e. [18F]-FTHA can be obtained without HPLC purification step
Subject(s)
Fluorides , Positron-Emission Tomography , Fatty Acids , MyocardiumABSTRACT
Bleomycin [BLM] has been labeled with radioisotopes and widely used in therapy and diagnosis. In this study BLM was labeled with [62Zn] zinc chloride for oncologic PET studies. The complex was obtained at the pH=2 in normal saline at 90°C in 60 min. Radio-TLC showed an overall radiochemical yield of 95-97% [radiochemical purity > 97%]. Stability of complex was checked in vitro in mice and human plasma/urine. Preliminary in vivo studies performed to determine complex stability and distribution of [62Zn] BLM in normal and fibrosarcoma-bearing mice. [62Zn] BLM accumulated significantly in induced fibrosarcoma tumors in mice according to bio-distribution/imaging studies. [62Zn] BLM can be used in PET oncology studies due to its suitable physico-chemical properties as a diagnostic complex in vitro and in vivo. Further studies should be performed for evaluation of the complex behavior in higher animals