ABSTRACT
The goal of this study was to determine the quantitative accuracy of our OSEM-APDI reconstruction method based on SPECT/CT imaging for Tc-99m, In-111, I-123, and I-131 isotopes. Phantom studies were performed on a SPECT/low-dose multislice CT system (Infinia-Hawkeye-4 slice, GE Healthcare) using clinical acquisition protocols. Two radioactive sources were centrally and peripherally placed inside an anthropometric Thorax phantom filled with non-radioactive water. Corrections for attenuation, scatter, collimator blurring and collimator septal penetration were applied and their contribution to the overall accuracy of the reconstruction was evaluated. Reconstruction with the most comprehensive set of corrections resulted in activity estimation with error levels of 3-5% for all the isotopes.
Subject(s)
Tomography, Emission-Computed, Single-Photon/methods , Tomography, X-Ray Computed/methods , Algorithms , Anthropometry , Humans , Image Processing, Computer-Assisted , Indium Radioisotopes/pharmacology , Iodine Radioisotopes/pharmacology , Models, Statistical , Phantoms, Imaging , Photons , Positron-Emission Tomography/methods , Reproducibility of Results , Technetium/pharmacology , Thorax/pathologyABSTRACT
Diets containing essentially no fat, 1-2 g fat per day, have resulted in cholesterol gallstones. Greater fat may result in less gallbladder stasis. Do gallstones form with greater fat content? We studied 272 moderately obese subjects who had normal gallbladder ultrasonograms. The 900 kcal/day liquid diets contained either 16 g fat (N = 94) or 30 g fat (N = 178) each day for 13 weeks. A second gallbladder ultrasound was performed. Sixteen of 94 (17.0%) of the 16-g fat group developed stones with a weight loss of 18 (+/- 7) kg and a body mass index (BMI) decrease of 6 (+/- 2) kg/m2. Twenty of 178 (11.2%) of the 30-g fat group developed stones (P = 0.18, no difference in stone formation) with similar weight loss of 20 (+/- 7) kg (P = 0.08) and BMI decrease of 7 (+/- 2) kg/m2 (P = 0.04). Substantial fat for rapid weight-reducing diets resulted in gallstone formation. Since experiments have shown that our higher fat diet, containing 10 g fat per meal, results in maximal gallbladder emptying, cholelithiasis from rapid weight loss may not be solely attributable to gallbladder stasis.
Subject(s)
Cholelithiasis/etiology , Diet, Fat-Restricted , Diet, Reducing , Dietary Fats/administration & dosage , Gallbladder Emptying/physiology , Obesity, Morbid/diet therapy , Obesity/diet therapy , Case-Control Studies , Cholelithiasis/diagnostic imaging , Cholelithiasis/epidemiology , Energy Intake , Female , Food, Formulated , Gallbladder/diagnostic imaging , Humans , Male , Prospective Studies , Risk Factors , Time Factors , UltrasonographyABSTRACT
The exposure of nuclear medicine technologists to airborne radiocontaminants is generally far below the compliance limits. Most of the contamination is external rather than internal deposition. Higher contamination levels approaching the allowable limits are rare. Personal respiratory protection is unwarranted and may have undesirable impressions on patients undergoing lung scanning. Exposures are well controlled by suitable work practices that are in keeping with as low as reasonably achievable (ALARA) principles.
Subject(s)
Allied Health Personnel , Lung/diagnostic imaging , Occupational Exposure/prevention & control , Radiation Protection , Radionuclide Imaging/adverse effects , Aerosols , Equipment Failure , Humans , Patient Education as Topic , Radiation Monitoring , Radionuclide Imaging/instrumentation , Respiratory Protective DevicesABSTRACT
Twenty-three morbidly obese patients underwent gastric emptying studies (Tc-99m egg salad sandwich--a semisolid meal) preoperatively, and at three months and 12 months postoperatively to evaluate the effect of transverse gastroplasty on gastric emptying and to determine the predictive value of this study for weight loss. At three months pouch emptying was variable with nine of 23 patients having prolonged half-times, and 14 shortened half-times compared with preoperative values, despite both groups having identical weight loss. At 12 months pouch half-times returned to baseline. The data suggests that this type of gastroplasty causes weight loss solely by reducing the gastric volume resulting in reduced meal volume. Weight loss is not related to impaired pouch emptying, which might result in a prolonged feeling of fullness. Gastric emptying studies neither preoperatively nor postoperatively have weight loss predictive value for this particular operation.