نتایج جستجو برای: dose calibrator
تعداد نتایج: 311008 فیلتر نتایج به سال:
The protein-based secondary standardsfor serum fructosamine in a commercial test kit (Roche Diagnostics) have recently been modified by the manufacturer. Under certain assay conditions, the new calibrator gave significantly greater serum fructosamine values than those obtained with the originally supplied calibrator. However, for 20-4, samples and absorbance measurements at 10 and 15 mm, hereaf...
BACKGROUND Errors of calibrator-assigned values lead to errors in the testing of patient samples. The ability to estimate the uncertainties of calibrator-assigned values and other variables minimizes errors in testing processes. International Organization of Standardization guidelines provide simple equations for the estimation of calibrator uncertainty with simple value-assignment processes, b...
This article reviews routine quality-control (QC) procedures for current nuclear medicine instrumentation, including the survey meter, dose calibrator, well counter, intraoperative probe, organ ("thyroid") uptake probe, gamma-camera, SPECT and SPECT/CT scanner, and PET and PET/CT scanner. It should be particularly useful for residents, fellows, and other trainees in nuclear medicine, nuclear ca...
CONTEXT AND OBJECTIVE Studies using radionuclides are the most appropriate method for estimating renal function. Dimercaptosuccinic acid chelate labeled with technetium-99m (99mTc-DMSA) is the radiopharmaceutical of choice for high-resolution imaging of the renal cortex and estimation of the functional renal mass. The aim of this study was to evaluate a simplified method for determining the abs...
Quantitative PET imaging is an important tool for clinical trials evaluating the response of cancers to investigational therapies. The standardized uptake value, used as a quantitative imaging biomarker, is dependent on multiple parameters that may contribute bias and variability. The use of long-lived, sealed PET calibration phantoms offers the advantages of known radioactivity activity concen...
We describe the design and calibration of an external cryogenic blackbody calibrator used for the first two flights of the Absolute Radiometer for Cosmology, Astrophysics, and Diffuse Emission (ARCADE) instrument. The calibrator consists of a microwave absorber weakly coupled to a superfluid liquid helium bath. Half-wave corrugations viewed 30° off axis reduce the return loss below −35 dB withi...
UNLABELLED A multi-centre trial using PET requires the analysis of images acquired on different systems We designed a multi-centre trial to estimate the value of 18F-FLT-PET to predict response to neoadjuvant chemotherapy in patients with newly diagnosed breast cancer. A calibration check of each PET-CT and of its peripheral devices was performed to evaluate the reliability of the results. MA...
UNLABELLED The purpose of this study was to measure the errors introduced by regular calibration of PET/CT scanners and to minimize the effect of calibration error on standardized uptake value measurements. METHODS Global calibration factors from 2 PET/CT scanners were recorded for 3.5 and 1.8 y, comparing manufacturer-recommended protocols with modified protocols to evaluate error contributi...
This multicenter study aimed to determine the reproducibility of quantitative SPECT images reconstructed using a commercially available method ordered-subset conjugate-gradient minimization. Methods: A common cylindric phantom containing 100 kBq/mL concentration 99mTc-pertechnetate solution in volume 7 L was scanned under standard imaging conditions at 6 institutions local cli...
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