With the radioactivity clearance curve of 99mTc-DTPA which was injected into the flusing device, the authors measured cerebrospinal fluid(CSF) flow rate through the shunt tube. The CSF flow rates in resting state in control group and malfunction group were considerably variable and there was no difference of CSF flow rates between the two groups. The significance, advantages, and problems of CSF flow rate measurement were discussed. The changes of CSF flow rate according to physiologic and pathologic fluctuation of intracranial pressure(ICP) should be taken into consideration for a valuable clinical application of this study.
Radioactivity

No abstract available.
Liver* ; Radioactivity* ; Radionuclide Imaging*

Radionuclide therapy has been an important field in nuclear medicine. In radionuclide therapy, relevant evaluation of internally absorbed dose is essential for the achievement of efficient and sufficient treatment of incurable disease, and can be accomplish by means of accurate measurement of radioactivity in body and its changes with time. Recently, the advances of nuclear medicine imaging and multi?modality imaging processing techniques can provide chance of more accurate and easier measurement of the measures commented above, in cooperation of conventional imaging?based approaches. In this review, basic concept for internal dosimetry using nuclear medicine imaging is summarized with several check points which should be considered in real practice.
Nuclear Medicine* ; Radioactivity ; Radiometry*

Radionuclide therapy has been an important field in nuclear medicine. In radionuclide therapy, relevant evaluation of internally absorbed dose is essential for the achievement of efficient and sufficient treatment of incurable disease, and can be accomplish by means of accurate measurement of radioactivity in body and its changes with time. Recently, the advances of nuclear medicine imaging and multi?modality imaging processing techniques can provide chance of more accurate and easier measurement of the measures commented above, in cooperation of conventional imaging?based approaches. In this review, basic concept for internal dosimetry using nuclear medicine imaging is summarized with several check points which should be considered in real practice.
Nuclear Medicine* ; Radioactivity ; Radiometry*

OBJECTIVE: Radiation is used extensively in emergency centers. Computed tomography and X-ray imaging are used frequently. Portable X-rays, in particular, cause a significant amount of indirect radiation exposure to medical personnel. The authors' emergency center was remodeled, and a comparative study of radiation exposure was carried out in certain places that had experienced radiation for a long time. METHODS: The cumulative radiation dose was measured 20 times in the 24 hours prior to remodeling, and the cumulative radiation dose was measured again 20 times across the 24-hour period. The measurement points were fixed at the emergency doctor's seat (Zone A), charge nurse's seat (Zone B), and section nurse's seat (Zone C). During the 24-hour cumulative radiation measurement period, the number of portable X-ray shots was recorded in the emergency center. RESULTS: The mean of the 24-hour cumulative radiation measurements in zone A was 3.36±0.07 µSV and 4.54±0.07 µSV before and after remodeling, respectively (P<0.001). Regarding the number of portable X-rays performed during the measurement, a higher number of trials in the Pearson correction correlated with a higher radiation measurement. CONCLUSION: In an emergency medical center, there is a higher level of low-dose radiation exposure compared to that experienced from natural radioactivity. Regarding the number of portable X-rays, the cumulative radiation dose measured 24 hours after remodeling increased and can be assumed to be related to the environment.
Emergencies ; Radiation Exposure ; Radioactivity

The technetium (Tc)-99m pyrophosphate scans have been used to diagnose acute myocardial infarctions and to confirm the equivocal cases. Many articles have been reported about its diagnostic performance and pitfalls. But there has been no evaluation of its predictability according to the grades of the radioactivity land statistical evaluation of the trade-off point, i.e., grade 2 and the area under the receiver operating characteristic curve. To achieve the goals, we reviewed 252 cases of Tc-99m pyrophosphate scans (acute transmural infarction [n=99], acute subendocardial infarction [n=7], unstable angina[n=16], old myocardial infarction [n=19] others [n=111]). The predictabilities of the scan are 98% in grade 4, 84% in grade 3, 83% in grade 2, 53% in grade 1 and 18% in non-uptake. The usual trade-off point, grade 2 is not statistically significant(Z=1.945, P=0.0259>0.01). The area under the receiver operating characteristic curve(Az) is 0.885. Our study shows that the probable main cause of the false negative cases is the time interval between the onset of symptoms and the test.
Infarction ; Myocardial Infarction ; Radioactivity ; ROC Curve ; Technetium

Technisium ((99m)Tc) is one of the most widely used radioactive isotopes for diagnosis in nuclear medicine. In general, technisium is produced inside the so called (99m)Tc generator which is usually made out of lead to shield relatively high energy radiation from (99)Mo and its daughter nuclide (99m)Tc. In this paper, a GEANT4 simulation is carried out to test the safety of the (99m)Tc generator, taking the Daiichi product with radioactivity of 500 mCi as an example. According to the domestic regulation on radiation safety, the dose at 10 cm and 100 cm away from the surface of shielding container should not exceed 2.0 mSv/h and 0.02 mSv/h, respectively. The simulated dose turned out to be less than the limit, satisfying the domestic regulation.
Nuclear Family ; Nuclear Medicine ; Radioactivity ; Radioisotopes

PURPOSE: We determined whether the uptake of Ga-67 by cultured cells occur by both transferrin (Tf)-dependent and independent mechanisms and the mechanism and magnitude of its uptake may vary as the degree of expression of the transformed phenotype. MATERIALS AND METHODS: Uptake of Ga-67 between the tansformed and untransformed cells was compared. Cells were incubated with Ga-67 in either the presence or absence of Tf and with complete medium containing Ga-67 after preincubating with anti-Tf receptor antibodies at 37oC in 8% CO2. Monolayers of cells were washed and trypsinized. Radioactivity and protein content of the samples were determined. RESULTS: Uptake of Ga-67 by cultured cells occurred both in Tf-bound and ionic form and was increased with radioactivity and time. The magnitude for the uptake of Tf-bound form was approximately 3 and 6-fold greater than ionic form. In the presence of Tf, uptake of Ga-67 was 2-fold greater in the transformed cells. Conversely, In the absence of Tf, it was 1.5-fold greater in the untransformed cells. Regardless of blocking the Tf receptor by anti-Tf receptor antibodies, a significant amount of intracellular Ga-67 uptake was found. CONCLUSION: Dual mechanisms exist for the uptake of Ga-67 by cultured cells. The primary important one was the Tf-dependent system. Tf-dependent and independent mechanisms and the magnitude operated oppositely in the transformed cells when compared to their untransformed counterpart.
Antibodies ; Cells, Cultured* ; Phenotype ; Radioactivity ; Transferrin ; Trypsin

PURPOSE: The purpose of this study was to develop a small animal PET using dual layer phoswich detector to minimize parallax error that degrades spatial resolution at the outer part of field-of-view (FOV). MATERIALS AND METHODS: A simulation tool GATE (Geant4 Application for Tomographic Emission) was used to derive optimal parameters of small PET, and PET was developed employing the parameters. Lutetium Oxyorthosilicate (LSO) and Lutetium-Yttrium Aluminate-Perovskite (LuYAP) was used to construct dual layer phoswitch crystal. 8 X 8 arrays of LSO and LuYAP pixels, 2 mm X 2 mm X 8 mm in size, were coupled to a 64-channel position sensitive photomultiplier tube. The system consisted of 16 detector modules arranged to one ring configuration (ring inner diameter 10 cm, FOV of 8 cm). The data from phoswich detector modules were fed into an ADC board in the data acquisition and preprocessing PC via sockets, decoder block, FPGA board, and bus board. These were linked to the master PC that stored the events data on hard disk. RESULTS: In a preliminary test of the system, reconstructed images were obtained by using a pair of detectors and sensitivity and spatial resolution were measured. Spatial resolution was 2.3 mm FWHM and sensitivity was 10.9 cps/micro Ci at the center of FOV. CONCLUSION: The radioactivity distribution patterns were accurately represented in sinograms and images obtained by PET with a pair of detectors. These preliminary results indicate that it is promising to develop a high performance small animal PET.
Animals* ; Electrons* ; Lutetium ; Positron-Emission Tomography* ; Radioactivity

PURPOSE: The pvrpose of this study was to evaluate the accuracy of radioactivity quantitation in Tc-99m SPECT by using combined scatter and attenuation correction. MATERIALS AND METHODS: A cylindrical phantom which simulates tumors (T) and normal tissue (B) was filled with varying activity ratios of Tc-99m. We acquired emission scans of the phantom using a three-headed SPECT system (Trionix, Inc.) witb two energy windows (photopeak window: 126 154 keV and scatter window: 101 123 keV). We performed the scatter correction with dual-energy window subtraction method (k=0.4) and Chang attenuation correction. Three sets of SPECT images were reconstructed using combined scatter and attenuation correction (SC+AC', attenuation correction (AC) and without any correction (NONE). We compared T/B ratio, irnage contrast [(T-B)/(T+B)) and absolute radioactivity with true values. RESULTS: SC+AC images had the highest mean values of T/B ratios. Image contrast was 0.92 in SC+AC, which was close to the true value of 1, and higher than AC (0.77) or NONE (0.80). Errors of true activity by SPECT images ranged from 1 to 11% for SC+AC, 22-47% for AC, and 2 16% for NONE in a phantom which was located 2.4cm from the phantom surface. In a phantom located 10,0cm from the surface, SC+AC underestimated by ?4%, NON.E 40%. However, AC overestimated by 10%. CONCLUSION: We conclude that accurate SPECT activity quantitation of Tc-99m distribution can be achieved by dual window scatter correc.tion combined with attenuation correction.
Radioactivity ; Tomography, Emission-Computed, Single-Photon*