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At least 145 records · Page 8Linked to original sources

PubMed2005

Study of flow characteristics in a secondary clarifier by numerical simulation and radioisotope tracer technique.

Numerical simulation in a 2-D rectangular coordinate and experimental study have been performed to figure out the flow characteristics and concentration distribution of a large-scale rectangular final clarifier in wastewater treatment facility located in Busan, S. Korea. The purpose of numerical calculation is to verify the experimentally measured data by radioisotope tracer technique and further to understand the important physical feature occurring in a large-scale clarifier, in many cases which is not sufficient by the aid of limited number of experimental data. To this end, a comprehensive computer program is basically made by SIMPLE algorithm by Patankar with the special emphasis on the parametric evaluation of the various phenomenological models. Calculation results are successfully evaluated against experimental data obtained by the method of radioisotope tracer. Detailed comparison is made on the calculated residence time distribution (RTD) curves with measurement inside the clarifier as well as the exhaust. Further the calculation results predict well the well-known characteristics of clarifier flow such as the waterfall phenomenon at the front end of the clarifier, the bottom density current in the settling zone and the upward flow in the withdrawal zone. Thus it is believed that the flow calculation program and the data incorporation technique of radioisotope measurement employed in this study show the high possibility as a complementary tool of experiment in this area.

Journal Article↗

PubMed2003

Assessment of statistic analysis in non-radioisotopic local lymph node assay (non-RI-LLNA) with alpha-hexylcinnamic aldehyde as an example.

The murine local lymph node assay (LLNA) is used for the identification of chemicals that have the potential to cause skin sensitization. However, it requires specific facility and handling procedures to accommodate a radioisotopic (RI) endpoint. We have developed non-radioisotopic (non-RI) endpoint of LLNA based on BrdU incorporation to avoid a use of RI. Although this alternative method appears viable in principle, it is somewhat less sensitive than the standard assay. In this study, we report investigations to determine the use of statistical analysis to improve the sensitivity of a non-RI LLNA procedure with alpha-hexylcinnamic aldehyde (HCA) in two separate experiments. Consequently, the alternative non-RI method required HCA concentrations of greater than 25% to elicit a positive response based on the criterion for classification as a skin sensitizer in the standard LLNA. Nevertheless, dose responses to HCA in the alternative method were consistent in both experiments and we examined whether the use of an endpoint based upon the statistical significance of induced changes in LNC turnover, rather than an SI of 3 or greater, might provide for additional sensitivity. The results reported here demonstrate that with HCA at least significant responses were, in each of two experiments, recorded following exposure of mice to 25% of HCA. These data suggest that this approach may be more satisfactory-at least when BrdU incorporation is measured. However, this modification of the LLNA is rather less sensitive than the standard method if employing statistical endpoint. Taken together the data reported here suggest that a modified LLNA in which BrdU is used in place of radioisotope incorporation shows some promise, but that in its present form, even with the use of a statistical endpoint, lacks some of the sensitivity of the standard method. The challenge is to develop strategies for further refinement of this approach.

Acrolein↗

PubMed2001

Pre-concentration and measurement of low levels of gamma-ray emitting radioisotopes in coastal waters.

We describe extensive testing of a large-volume, high-speed water sampler for the concentration and measurement of radionuclides using high-resolution gamma ray spectrometry. The sampler processed hundreds to thousands of liters of natural waters with variable suspended sediment and salinity loads at flow rates of 10-201/min. Extraction of most radionuclides in the water column was accomplished through the combination of physical filtration down to 0.1 microm particle size and chemical separation of dissolved species on cellulose-based inorganic sorbent beds without recourse to complex, or hazardous chemistry. Performance and extraction efficiencies for suites of radioisotopes were determined in the laboratory and in the field with river and coastal ocean water samples. Extraction and recovery efficiencies are better than 90% for most fission and activation product radioisotopes. This methodology has broad application to the study of the distribution and fate of radioisotopes in coastal waterways.

Journal Article↗

PubMed2003

Bronchoscopic radioisotope injection for sentinel lymph-node mapping in potentially resectable non-small-cell lung cancer.

OBJECTIVE: Prospective study to evaluate the feasibility of a preoperative bronchoscopic radioisotope application, followed by conventional sentinel lymph-node (SLN) identification and to investigate the occurrence and distribution of micrometastases in relation to SLN activity. METHODS: Twenty patients with a mean age of 63 years and proven clinical stage T1-3 N0-1 non-small-cell lung cancer (NSCLC) were included. A dosage of 80MBq radiolabeled technetium-99m nanocolloid was endoscopically administrated on intubated patients in the operation theatre. At thoracotomy, scintigraphic readings of both the primary tumor and hilar and mediastinal lymph-node stations were obtained with a hand-held gamma-counter. Patients underwent lung resection and mediastinal lymphadenectomy. Radiolabeled nodes were also examined separately on back-table. SLNs were defined as the hottest nodes or nodes with at least one-tenth of the radioactivity of the hottest nodes. SLNs pathologic assessment included standard examination using hematoxylin and eosin staining on step sections and immunohistochemistry (ICH) for cytokeratins. RESULTS: Identification of SLNs was possible in 19/20 (95%) patients after bronchoscopic radioisotope application. In 7/19 (37%) patients, a unique SLN was identified, whereas in 12/19 (63%) patients, nodes from two different stations could be classified as SLNs. Metastatic nodal disease was found in 9/19 (47%) patients. ICH revealed micrometastases in 2/12 (17%) patients, initially classified nodal negative. Pathologic negative SLNs were a predictor for absence of metastatic nodal disease after mediastinal lymphadenectomy. No complication related to the procedure was observed. CONCLUSION: Our preliminary results suggest that preoperative bronchoscopic radioisotope injection for SLN identification is a safe and simple method, improving accuracy of SLN detection in comparison to intraoperative technique. The absence of metastases in the SLNs seems to predict a negative nodal status accurately.

Aged↗

PubMed2003

On-line liquid chromatography-accurate radioisotope counting coupled with a radioactivity detector and mass spectrometer for metabolite identification in drug discovery and development.

A novel detection method combining on-line liquid chromatography-accurate radioisotope counting (LC-ARC, advanced stop flow controller) coupled with a radioactivity detector and mass spectrometer has been developed. One of the major benefits of this method is that this system enhances the sensitivity of radioisotope measurement for metabolite identification in drug metabolism studies. Another advantage to this system is the easy interface with the mass spectrometer, which allows acquisition of mass spectrometric data on-line. For purposes of evaluating this system, in vitro microsomal incubations with [3Hlpropranolol were conducted. On-line separation and identification of [3H]propranolol metabolites was achieved without intensive sample preparation, concentration, or fraction collection. Mass spectrometric analysis showed the presence of propranolol major metabolites formed by hydroxylation, correlating with previously published results. Further evaluations of this system also were conducted using two 14C compounds, which are herein labeled X and Y. As our results show, 14C peaks were detected down to 6 cpm, which is approximately 20 times more sensitive than commercially available flow through radioactivity detectors. The overall results suggest that the combination of LC-ARC with radioactivity detection and mass spectrometry has great potential as a powerful tool for improving the sensitivity of radioisotope measurement in metabolite identification studies during drug discovery and development.

Animals↗

PubMed2006

A second radioisotope injection enhances intraoperative sentinel node identification in breast cancer patients without visualized nodes on preoperative lymphoscintigraphy.

PURPOSE: To evaluate the influence of a second radioisotope injection on the intraoperative success rate in patients with non-visualized axillary sentinel nodes (SN). MATERIAL AND METHODS: Altogether, 534 consecutive breast cancer patients with lymphoscintigraphy (LS) and SN biopsy and were included. An intratumoral injection of 99mTc-labeled human albumin colloid with a median dose of 93 MBq was applied. Forty-two of the 80 patients without axillary hot spots on LS received a second tracer injection with a median dose of 70 MBq. RESULTS: The visualization rate of axillary SN was 454/534 (85%). The intraoperative SN identification rate was 97% in patients with and 69% in patients without visualized SN in the axilla (P<0.00005), but the success rate was higher (88%) with a second radioisotope injection than without it (47%; P<0.0002). CONCLUSION: The failure rate in intraoperative SN identification was minimized using a second radioisotope injection in patients without axillary SN on LS.

Adult↗

PubMed2002

Radioisotope stents.

Intracoronary stent placement following PTCA improves the long-term outcome of the treated patient, but in-stent restenosis remains problematic, especially in smaller vessels and longer lesions. Intravascular brachytherapy is a rapidly evolving field of research and clinical treatment, with a number of different irradiation techniques being used clinically. Many clinical data are now available that indicate clearly that either &#110 or &#103 radiation can reduce, and hopefully cure restenosis. The combination of radiation with stents has several distinct advantages over radiation with balloon angioplasty. It should be possible to use the stent as the radioactive source, as the radioactivity levels required by a permanent implant are extremely safe (< 1/1000 of the radioactivity of the least radioactive brachytherapy catheters). Once the stent has been implanted, the procedure is complete; catheter-based brachytherapy requires a second procedure after stent implantation. Unfortunately, in many human studies of the efficacy of radioisotope stents, although an excellent result in terms of a dramatically reduced neointima was seen in the stent, the incidence of an 'edge effect', with a reduced lumen just beyond the stent-edge occurred at an unacceptable rate. The encouraging results of the 'hot ends' study, where the stent ends were made more radioactive to reduce the edge effect, coincided with even more encouraging results from sirolimus drug-eluting stents. As a result, most work on radioisotope stents for the treatment of restenosis has been abandoned. There may, however, be applications for radioisotope stents in the treatment of malignant ducts, such as the esophagus and bronchia, which could justify further study of the devices.

Journal Article↗

PubMedDate not supplied

Evaluation of the benefit of using blue dye in addition to radioisotope for sentinel lymph node biopsy in patients with breast cancer.

The techniques for performing sentinel lymph node biopsy (SLNB) vary from institution to institution. Some advocate blue dye only, others radioisotope only, and many utilize a combination of both. The purpose of this study is to evaluate the additional benefit that blue dye provides when used in combination with a radioisotope. From October 2001 to June 2004, 102 SLNBs were attempted in 99 patients with breast cancer using a combination of blue dye and radioisotope. A lymph node was considered a sentinel lymph node (SLN) when it was stained with blue dye, had a blue lymphatic afferent, or had increased radioactivity. Ninety-eight patients had 101 successful identifications of SLNs, for an identification rate of 99%. Twenty-eight patients had positive SLNs. In three of those patients, although there were SLNs identified by both techniques, the positive SLNs were identified with only blue dye. Of the 102 SLNB procedures, there were two patients whose only SLN was identified by blue dye only. Although blue dye did not improve the identification rate, there was a definite benefit in improving the false-negative rate.

Breast Neoplasms↗

PubMed2004

Use of radioisotopic esophageal transit in the assessment of patients with symptoms of reflux and non-specific esophageal motor disorders.

The purposes of this study were to assess the esophageal clearance of a radioisotopic bolus in patients with symptoms of reflux and evaluate the impact of manometric abnormalities on scintigraphic esophageal transit. Esophageal clearance was assessed in a supine position and indicated by the retained radioactivity in the esophagus at 10, 20, 30 and 40 s after the ingestion of a liquid bolus labeled with 2 mCi 99 mTc-SC. The study included 214 consecutive patients with symptoms of reflux and 11 normal controls. The results were compared to the motility findings detected on manometry performed on a separate occasion. Esophageal manometry was normal in 93 patients. Nonspecific esophageal motor disorders were identified in 121 patients and were classified into: 'predominantly nonpropagated activity', 'predominantly low-amplitude peristaltic contractions' and 'miscellaneous disorders' diagnosed in 27, 47 and 47 patients, respectively. The radionuclide clearance was significantly delayed in the overall group of patients compared with that of normal controls (P < 0.001); in patients with reflux symptoms and nonspecific esophageal motor disorders compared with patients with reflux symptoms and 'normal manometry' (P < 0.01 at 20 s); and in patients with reflux symptoms and 'normal manometry' compared with the control group (P < 0.01 at 20 s). Abnormal radioisotope clearances were detected in 88% of patients with 'predominantly nonpropagated activity', in 70% of patients with 'predominantly low-amplitude peristaltic contractions' and in 57% of patients with 'miscellaneous disorders'. Radioisotopic esophageal clearance abnormalities are frequently observed in patients with reflux symptoms and are more likely to be associated to hypomotility disorders, i.e. nonpropagated motor activity or low-amplitude contractions.

Administration, Oral↗

PubMed1977

A comparison of radiography and radioisotope scanning in the detection of Paget's disease and in the assessment of response to human calcitonin.

In eight patients with symptomatic Paget's disease, radiographs and radioisotope bone scans have been compared before treatment by high dose synthetic human calcitonin (CIBA 47175-Ba) and three months and 12 months later. In six patients quantitative radioisotope scans allowed calculation of relative radioactivity in normal bone, Paget's disease and bone adjacent to osteoarthritic joints. Comparison of radiographs and scans showed 69 sites diagnosed as Paget's disease on both examinations; nine sites showed radiographic changes of Paget's disease but had negative radioisotope scans and two sites were abnormal on the scan but radiologically normal. One of these two reverted towards normal during treatment with calcitonin. Comparison of analogue scans done at three months and 12 months with initial scans showed diminished uptake in Paget's disease compared with normal bone, and quantitation showed this was due to decreased absolute uptake in Paget's disease and a slight increase in normal bone. Osteoarthritic bone showed no significant response to calcitonin.

Aged↗

PubMed1980

The detection of pyelonephritic scarring in children by radioisotope imaging.

Radioisotope scintigraphy of the kidney and intravenous urography have been compared in 79 children with bacteriologically proven urinary tract infections, followed up over a period of between one and four years. Both techniques were in agreement as to the presence or absence of an abnormality, and the extent of any abnormality present, in 93.5% of the kidneys studied. There was a discrepancy in ten kidneys. Excretion urography has a sensitivity of 0.86 and a specificity of 0.92 in the detection of pyelonephritic scarring in children. Radioisotope scintigraphy has a sensitivity of 0.96 and a specificity of 0.98. It is therefore concluded that radioisotope scintigraphy is the preferred technique.

Atrophy↗

PubMed1981

The use of radioisotope scans in the preoperative evaluation of epidermoid carcinoma of the head and neck.

Because of the growing awareness of metastatic disease in head and neck patients, a protocol including radioisotope scans was begun through the Baylor Department of Otolaryngology at the Houston V.A. Hospital in an attempt to identify these patients preoperatively. Out of 198 death charts reviewed, only 3 had positive preoperative scans and only one of these was clinically significant. Chest X-rays identified more preoperative metastatic disease than the radioisotope scans. Twenty percent of patients had second primaries, which was more than the number of patients dying with distant metastatic disease. Only 5% of these patients died of metastatic disease with local control. Local control with follow-up for second primaries should be the primary objective of the surgeon. Radioisotope scans were of no significant value in evaluating preoperative metastatic disease.

Carcinoma, Squamous Cell↗

PubMed2003

Radioisotope marking under CT guidance and localization using a handheld gamma probe for small or indistinct pulmonary lesions.

STUDY OBJECTIVES: A new marking technique was developed to localize small or indistinct pulmonary lesions, involving preoperative radioisotope injection and intraoperative detection with a handheld gamma probe. SETTING: National hospital for respiratory disease. METHODS: and patients: A technetium suspension (either (99m)Tc tin colloid [2 to 4 mCi, 0.5 to 2.5 mL] or (99m)Tc phytate [2 mCi, 2.0 mL]) was injected preoperatively in the vicinity of the lesion under CT guidance in 25 patients with small or indistinct pulmonary lesions. A handheld gamma probe (Navigator GPS; Tyco Healthcare Japan; Tokyo, Japan) was used to detect the hot spot where radioactivity was localized during surgery. The lesion marked by the radioisotope then was thoracoscopically resected using endostaplers. RESULTS: The preoperative marking procedure took approximately 30 min. A small pneumothorax and mild intrapulmonary bleeding were observed in two patients and one patient, respectively, but no additional treatment was needed for these complications. The lesion was resected soon after the marking procedure in 21 patients, and on the next day in 4 patients. All lesions were easily identified during surgery as radioactive hot spots detected by the handheld gamma probe. Thoracoscopic wedge resection was successfully performed in all patients without complications. CONCLUSION: This new marking technique for small or indistinct pulmonary lesions (radioisotope injection under CT guidance and intraoperative detection with a handheld gamma probe) seems to be safe, reliable, and convenient.

Colloids↗

PubMed2002

Effects of radioisotopes on the accuracy of dual-energy X-ray absorptiometry for bone densitometry.

Nuclear medicine procedures are often performed in close-time proximity to bone densitometry studies. The purpose of this study was to determine the effects of various radioisotopes on the accuracy of bone mineral density (BMD) measurements performed using dual-energy x-ray absorptiometry (DEXA) systems. We evaluated two DEXA scanners: the Hologic QDR4500 and the Lunar Prodigy. The effects of various activities of Tc-99m, Tl-201, Ga-67 and I-131 on BMD were assessed by placing vials or syringes containing the appropriate isotope above or below a simulated spine (average BMD = 1.1 g/cm2) embedded in a lucite block. We also placed a spine phantom (average BMD = 2.0 g/cm2) in a water bath containing various concentrations of Tc-99m. Maximum activities evaluated were as follows: Tc-99m, 80 mCi; I-131, 50 mCi; Tl-201, 66 mCi; Ga-67, 20 mCi. For the Hologic QDR4500 system, irrespective of the radioisotope or activity, we found no significant effect of adjacent activity on measured BMD on this system. For the Lunar Prodigy system, the effects of adjacent activity on BMD were found to be dependent on source location, strength, and radioisotope. For sources placed beneath the solid lucite phantom, BMD decreased by approx 0.5%/10 mCi of activity for all isotopes. In general, for sources placed above the lucite phantom, the BMD decreased by 1.6-4.0%/10 mCi of activity, depending on location. The exception was Tl-201, where BMD increased by 0.5-2.5%/10 mCi, depending on location. With the high-density spine in the water phantom, the effects of adjacent activity were more pronounced than in the standard density spine in the lucite block. For a distributed Tc-99m source, the BMD decreased by 1.7%/10 mCi. The effect of radioactivity on DEXA measurements is system dependent. In general, adjacent activity results in a reduction in apparent BMD. The magnitude of the effect increases with increasing BMD and is dependent on the location of the activity.

Absorptiometry, Photon↗

PubMed2002

Diagnosis of coronary artery disease based on blood pool radioisotope angiography at rest.

BACKGROUND: The author wanted to determine which of 3 parameters (global left ventricular ejection, regional left ventricular ejection fraction, or isocontours together with peak filling rate and time of peak filling rate) measured with blood pool radioisotope angiography at rest was sufficient to permit diagnosis of coronary artery disease. METHODS: Thirty-one patients with coronary artery disease and 11 hypertensive patients without coronary heart disease were assessed with blood pool radioisotope angiography using a computerized large-field gamma camera. RESULTS: Of the 3 parameters measured, only assessment of isocontours with peak filling rate and time of peak filling rate provided sufficient information for establishing a diagnosis of coronary artery disease. In contrast, measurement of global left ventricular ejection provided equivocal data, as did that of regional left ventricular ejection fraction. CONCLUSIONS: In combination with peak filling rate and time of peak filling rate, measurement of isocontours by blood pool radioisotope angiography at rest provided sufficient information for establishing a diagnosis of coronary artery disease.

Adult↗

PubMed1980

[Radioisotope lymphadenectomy in testicular tumors (author's transl)].

This paper presents a preliminary report of the first eleven patients with testicular cancer who underwent lymphadenectomy assisted by radioisotope techniques with a special designed gamma surgical camera. In cases of only partial carcinomatous infiltration the lymph nodes are well marked with the radioisotope. Additionally colour television gives the surgeon an objective continuous control of the actually dissected lymphatic tissue during all phases of surgery. In our experience the use of radioisotope-techniques and a gamma surgical camera seem to be of great value in improving lymph node extirpation in cases of testicular cancer.

Adolescent↗

PubMed1993

TESLA Accelerator Installation at Vinca. Production of radioisotopes for nuclear-medical applications.

The construction of the TESLA Accelerator Installation has been in progress under way at Vinca. It was designed so that the parameters of its main part-the VINCY Cyclotron enable, besides other applications, also the production of a number of radioisotopes which can be used in nuclear medicine. The production of a given radioisotope includes the choice of nuclear reaction (type, energy and beam current of accelerated particles, cross section, yield, etc), target (chemical form, isotopic composition, thermal stability), procedure of chemical treatment of the target after irradiation, procedure of labeling and quality control of the obtained radiopharmaceutical. In the paper these aspects are shown on the example of the production of radioisotope 123I.

Cyclotrons↗

PubMed1978

A preliminary study of the dynamics of resolution of experimental haematomas: radioisotope studies in animals.

A preliminary investigation was carried out in order to establish a method for the study of experimental haematomas. For this purpose haematomas were produced in rabbits by subcutaneous injection of rabbits' own blood after labelling the various blood components with appropriate radioisotopes. In addition, radioisotope labelled human serum albumin and fibrinogen were studied. The results show that there is considerable variation in the rate and pattern of dissipation of the various components of the experimentally produced haematoma. The significance of these findings is discussed.

Animals↗