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Abstract
ABSTRACTResistivity and grain size measurements on thin films of co-sputtered WSi2 show that the resistivity in this material is dominated by grain boundary scattering. The reflection coefficient for the transport of charge carriers through the grain boundaries was determined to be approximately 0.9.
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Chu RM, Chen QY, Chu WK. Angular-dependent I-V characteristics in borocarbide superconductor YNi(2)B(2)C. J Phys Condens Matter 2006; 18:4085-4092. [PMID: 21690760 DOI: 10.1088/0953-8984/18/16/015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
We present angular-dependent current-voltage (I-V) measurements in borocarbide YNi(2)B(2)C single crystals near the vortex-glass irreversible line. External magnetic fields are applied along the angle θ with respect to the c-axis. The nonlinear I-V curves reveal scaling behaviour near the transition. Using the scaling analysis, the relevant critical exponents and vortex transition temperatures are determined for all orientations. The data agrees well with the vortex-glass (VG) model. No evidence was found that supports the existence of a Bose-glass (BG) type of transition.
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Affiliation(s)
- R M Chu
- Bio-Nano Computational Laboratory (RCMI-NCRR) and Physics Department, Texas Southern University, Houston, TX 77004, USA
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Hornberger TA, Chu WK, Mak YW, Hsiung JW, Huang SA, Chien S. The role of phospholipase D and phosphatidic acid in the mechanical activation of mTOR signaling in skeletal muscle. Proc Natl Acad Sci U S A 2006; 103:4741-6. [PMID: 16537399 PMCID: PMC1450240 DOI: 10.1073/pnas.0600678103] [Citation(s) in RCA: 233] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Signaling by the mammalian target of rapamycin (mTOR) has been reported to be necessary for mechanical load-induced growth of skeletal muscle. The mechanisms involved in the mechanical activation of mTOR signaling are not known, but several studies indicate that a unique [phosphotidylinositol-3-kinase (PI3K)- and nutrient-independent] mechanism is involved. In this study, we have demonstrated that a regulatory pathway for mTOR signaling that involves phospholipase D (PLD) and the lipid second messenger phosphatidic acid (PA) plays a critical role in the mechanical activation of mTOR signaling. First, an elevation in PA concentration was sufficient for the activation of mTOR signaling. Second, the isozymes of PLD (PLD1 and PLD2) are localized to the z-band in skeletal muscle (a critical site of mechanical force transmission). Third, mechanical stimulation of skeletal muscle with intermittent passive stretch ex vivo induced PLD activation, PA accumulation, and mTOR signaling. Finally, pharmacological inhibition of PLD blocked the mechanically induced increase in PA and the activation of mTOR signaling. Combined, these results indicate that mechanical stimuli activate mTOR signaling through a PLD-dependent increase in PA. Furthermore, we showed that mTOR signaling was partially resistant to rapamycin in muscles subjected to mechanical stimulation. Because rapamycin and PA compete for binding to the FRB domain on mTOR, these results suggest that mechanical stimuli activate mTOR signaling through an enhanced binding of PA to the FRB domain on mTOR.
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Affiliation(s)
- T. A. Hornberger
- Department of Bioengineering and Whitaker Institute of Biomedical Engineering, University of California at San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0412
| | - W. K. Chu
- Department of Bioengineering and Whitaker Institute of Biomedical Engineering, University of California at San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0412
| | - Y. W. Mak
- Department of Bioengineering and Whitaker Institute of Biomedical Engineering, University of California at San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0412
| | - J. W. Hsiung
- Department of Bioengineering and Whitaker Institute of Biomedical Engineering, University of California at San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0412
| | - S. A. Huang
- Department of Bioengineering and Whitaker Institute of Biomedical Engineering, University of California at San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0412
| | - S. Chien
- Department of Bioengineering and Whitaker Institute of Biomedical Engineering, University of California at San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0412
- *To whom correspondence should be addressed. E-mail:
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Chu WK, Wong MH, Zhang J. Accumulation, distribution and transformation of DDT and PCBs by Phragmites australis and Oryza sativa L.: I. Whole plant study. Environ Geochem Health 2006; 28:159-68. [PMID: 16547765 DOI: 10.1007/s10653-005-9027-8] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
Glasshouse experiments were conducted to determine the accumulation, distribution and transformation of o,p'-DDT, p,p'-DDT and PCBs by common reed (Phragmites australis) and rice (Oryza sativa L.) under hydroponic conditions. The culture solution was spiked with the organic pollutants and samples were collected daily. Analysis of the plants at harvest showed that both species had removed DDT and PCBs from the solution. DDT appeared to have accumulated within P. australis by both passive adsorption and active absorption. Both o,p'-DDT and p,p'-DDT were transformed within P. australis. DDD was the major metabolite and the transformation was mediated by reductive dehalogenation. Plant long-distance transportation systems may be involved in the translocation of PCBs within P. australis and the affinity of the PCBs for lipids is one of the major factors affecting their uptake and translocation within the plants. Similar but less pronounced results were found in O. sativa and suggest that these wetland plants may be used for the plant-mediated remediation of persistent organic pollutants.
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Affiliation(s)
- W K Chu
- Department of Biology, Hong Kong Baptist University, Hong Kong, China
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Chu WK, Wong MH, Zhang J. Accumulation, distribution and transformation of DDT and PCBs by Phragmites australis and Oryza sativa L.: II. Enzyme study. Environ Geochem Health 2006; 28:169-81. [PMID: 16547764 DOI: 10.1007/s10653-005-9028-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
Two wetland plant species, Phragmites australis and Oryza sativa, were grown in a glasshouse under hydroponics conditions. Enzyme extracts from different parts of the plants were used to determine the transformation rate of o,p'-DDT, p,p'-DDT and PCBs. The organic pollutants were directly spiked into the enzyme extracts, and samples were collected every 30 min and analyzed with a GC-ECD. Root extracts of P. australis readily degraded and transformed DDT and some PCB congeners with a low degree of chlorination. In contrast, crude extracts of O. sativa showed no appreciable degradation or transformation of DDT or PCBs. Inhibition studies indicated that the degradation and transformation of both DDT and PCBs by P. australis enzymes were partly mediated by peroxidase and the plant P-450 system. PCBs with a high degree of chlorination were highly resistant to transformation or degradation by plant enzymes. Both wetland plant species accumulated substantial quantities of the persistent organic chemicals but had different degradation capacities. The enzyme systems in P. australis were much more effective that those in rice in the degradation and transformation of the organic pollutants.
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Affiliation(s)
- W K Chu
- Department of Biology, Hong Kong Baptist University, Hong Kong, China
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Chu WK, Nicolet MA, Mayer JW, Evans CA. Comparison of backscattering spectrometry and secondary ion mass spectrometry by analysis of tantalum pentoxide layers. Anal Chem 2002. [DOI: 10.1021/ac60350a039] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Chen JY, Chu WK, Wu HN, Hsu YL, Wu JL. Infectious Pancreatic Necrosis Virus RNA Cleavage In Vitro by Hammerhead Ribozymes and Enhancement of Ribozyme Catalysis by Oligonucleotide Facilitators. Mar Biotechnol (NY) 2000; 2:364-375. [PMID: 10960126 DOI: 10.1007/s101269900033] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Infectious pancreatic necrosis virus (IPNV), an aquatic birnavirus, has a bisegmented double-stranded RNA genome consisting of a 3.2-kb A segment and a 2.9-kb B segment. To determine the function of IPNV's viral proteins and to study the effects of viral RNA cleavage by hammerhead ribozymes, we cloned and sequenced the IPNV E1S strain of the A segment. After sequencing, we continued to study the virus pathogens inhibited by ribozyme cleavage and analyzed the cleavage of the virus RNA in vitro. The templates (VP2, 1220 bp) for in vitro transcription of S569 and S969 (substrates 569 and 969 bp in length) were synthesized by polymerase chain reaction. The DNA templates of hammerhead ribozymes targeted different sites in the partial sense RNA of IPNV. These templates were chemically synthesized RNAs prepared by runoff transcription of amplification products or synthetic DNA templates containing a T7 RNA polymerase promoter, and were used to characterize several properties of the cleavage reaction at 25 degrees C in 12 mM Mg(2+). Under this condition (25 degrees C, 12 mM Mg(2+)), the hammerhead ribozymes formed an estimated fraction of product during the reaction of only 30% in cleaving long RNA substrates in vitro. Short DNA facilitators (12 or 24-mers) that bind adjacent to either the 3' or 5' end of the ribozyme enhanced the rate of cleavage of the long RNA substrates containing 569 and 969 nucleotides, respectively, in trans. The hammerhead ribozymes with 3'-end facilitators reacted more efficiently (i.e., 65%).
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Affiliation(s)
- JY Chen
- Institute of Zoology, Academia Sinica, Taipei, Taiwan
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Ma DH, Tsai RJ, Chu WK, Kao CH, Chen JK. Inhibition of vascular endothelial cell morphogenesis in cultures by limbal epithelial cells. Invest Ophthalmol Vis Sci 1999; 40:1822-8. [PMID: 10393055] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/13/2023] Open
Abstract
PURPOSE To study the in vitro angiogenic activity of human conjunctival and limbal epithelial cells and conjunctival, limbal, and corneal fibroblasts in a three-cell-type coculture model. METHODS Human umbilical vein endothelial cells (EC) were cocultured with epithelial cells, fibroblasts, or epithelial cells and fibroblasts to test their effect on EC morphogenesis. Neutralizing antibodies to some known angiogenic factors were added to the culture to see whether the EC morphogenesis may be blocked by a particular antibody. RESULTS Conjunctival and limbal epithelial cells exhibited very little or no stimulatory effect on EC tube formation when examined in an EC- epithelial cell coculture system. In contrast, conjunctival, limbal, and corneal fibroblasts all promoted EC morphogenesis when examined under the same culture conditions. Fibroblast-induced EC morphogenesis was inhibited by addition of anti-vascular endothelial growth factor (VEGF) and/or anti-basic fibroblast growth factor (bFGF) antibodies to the culture medium. In the three-cell-type coculture system consisting of ECs, fibroblasts, and epithelial cells, limbal epithelial cells (but not conjunctival epithelial cells) exhibited a strong inhibitory effect on fibroblast-induced EC tube formation. CONCLUSIONS The proangiogenic activity of ocular surface fibroblasts is probably mediated through a paracrine mechanism by VEGF and bFGF. Limbal epithelial cells, but not conjunctival epithelial cells, inhibit fibroblast-stimulated angiogenesis.
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Affiliation(s)
- D H Ma
- Department of Ophthalmology, Change Gung Memorial Hospital, Tao-Yuan, Taiwan, Republic of China
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Abstract
Dosimetrists, physicists, and physicians rely heavily upon digital imaging modalities in their daily work. In the current healthcare marketplace, many radiotherapy facilities operate satellite centers or may be undergoing mergers with other service providers in their community. As a consequence, the development of network-based radiotherapy image communication may yield a significant impact on the clinical operation of such centers. Digital image networking will become an everyday tool in radiotherapy treatment planning in the near future. As responsible users of this technology, an accurate perception of what the network does is essential and enhances our ability to utilize it. This article presents a review of the network architecture and transmission standards necessary for understanding and developing a radiotherapy image network.
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Affiliation(s)
- C L Smith
- Department of Radiation Oncology, University of Nebraska Medical Center, Omaha 68198, USA
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Chu WK, Smith CL, Wobig RK, Hahn FA. An application of digital network technology to medical image management. Biomed Sci Instrum 1998; 34:287-90. [PMID: 9603054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
With the advent of network technology, there is considerable interest within the medical community to manage the storage and distribution of medical images by digital means. Higher workflow efficiency leading to better patient care is one of the commonly cited outcomes [1,2]. However, due to the size of medical image files and the unique requirements in detail and resolution, medical image management poses special challenges. Storage requirements are usually large, which implies expenses or investment costs make digital networking projects financially out of reach for many clinical institutions. New advances in network technology and telecommunication, in conjunction with the decreasing cost in computer devices, have made digital image management achievable. In our institution, we have recently completed a pilot project to distribute medical images both within the physical confines of the clinical enterprise as well as outside the medical center campus. The design concept and the configuration of a comprehensive digital image network is described in this report.
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Affiliation(s)
- W K Chu
- Department of Radiology, University of Nebraska Medical Center, Omaha 68198, USA
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Smith CL, Chu WK, Granville D, Nabity L. An examination of radiation exposure to clinical staff from patients implanted with 137Cs and 192Ir for the treatment of gynecologic malignancies. Health Phys 1998; 74:301-308. [PMID: 9482595 DOI: 10.1097/00004032-199803000-00002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
The treatment of cancers by placement of radioactive materials within or adjacent to a tumor is clinically known as brachytherapy. Although the intracavitary treatment of gynecologic cancers using 137Cs has been in widespread use for nearly a century, interstitial techniques using 192Ir have developed within the last decade. Both procedures are performed as temporary implants and typically require a hospital stay of approximately 48 h. Significant differences in source strengths, loading conditions, and patient care requirements are visible between the intracavitary and interstitial techniques. Facilities that are experienced in the use of intracavitary techniques may lack clinical experience in the use of newer interstitial procedures. An examination of radiation exposure to the radiation oncology staff administering the treatment, exposure rate at frequently occupied points in the patient room, and exposure to the nursing staff will be of value to those institutions considering integration of interstitial brachytherapy techniques into their department.
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Affiliation(s)
- C L Smith
- Department of Radiation Oncology, University of Nebraska Medical Center, Omaha 68198-1050, USA
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Sharma RP, Venkatesan T, Zhang ZH, Liu JR, Chu R, Chu WK. Evidence for Large Static and Dynamic Distortions in High Tc Superconducting YBa2Cu3O 7- delta Crystals over a Wide Temperature Range. Phys Rev Lett 1996; 77:4624-4627. [PMID: 10062585 DOI: 10.1103/physrevlett.77.4624] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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Smith CL, Chu WK, Goede MR, Granville D, Dalrymple GV. An analysis of the elements essential in the development of a customized TBI program. Med Dosim 1996; 21:49-56; quiz 58-60. [PMID: 8807604 DOI: 10.1016/0958-3947(96)00027-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Bone marrow transplant, once a procedure carried out at a relatively small number of large medical centers, is being employed at an increasing number of non-academic hospitals. The use of total body photon irradiation for the purpose of marrow ablation and immunosuppression can be expected to accompany the outward growth of bone marrow transplantation at these same hospitals. An analysis of the fundamental physical factors associated with total body photon irradiation (TBI) should be of value to facilities considering the incorporation of a total body irradiation program into an existing radiation oncology department. By examining the existing resources of a radiotherapy center and the clinical objectives of the treatment, a facility considering TBI may determine whether or not their center already fulfills the necessary criteria, in addition to the avoidance of potential pitfalls in project implementation.
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Affiliation(s)
- C L Smith
- Department of Radiation Oncology, University of Nebraska Medical Center, Omaha 68198, USA
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Rabalais JW, Al-Bayati AH, Boyd KJ, Marton D, Kulik J, Zhang Z, Chu WK. Ion-energy effects in silicon ion-beam epitaxy. Phys Rev B Condens Matter 1996; 53:10781-10792. [PMID: 9982646 DOI: 10.1103/physrevb.53.10781] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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McConnell JR, Antonson DL, Ong CS, Chu WK, Fox IJ, Heffron TG, Langnas AN, Shaw BW. Proton spectroscopy of brain glutamine in acute liver failure. Hepatology 1995; 22:69-74. [PMID: 7601435] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/06/2022]
Abstract
Evidence indicates that the accumulation of glutamine in the brain plays an important role in the pathogenesis and severity of the encephalopathy of acute liver failure (ALF). This study uses in vivo proton magnetic resonance spectroscopy (1H MRS) to assess brain glutamine (GLN) in five cases of acute liver failure. The findings are consistent with prior investigations and suggest that the alpha 1H of the GLN molecule can be used for noninvasive spectroscopic quantitation of brain GLN in patients with ALF.
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Affiliation(s)
- J R McConnell
- Department of Radiology, University of Nebraska Medical Center, Omaha 68198-1045, USA
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McConnell JR, Swindells S, Ong CS, Gmeiner WH, Chu WK, Brown DK, Gendelman HE. Prospective utility of cerebral proton magnetic resonance spectroscopy in monitoring HIV infection and its associated neurological impairment. AIDS Res Hum Retroviruses 1994; 10:977-82. [PMID: 7811549 DOI: 10.1089/aid.1994.10.977] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Neurological manifestations of HIV disease occur in most adults and children with AIDS. Many of those affected will inevitably suffer clinical neurological deficits involving mental function, movement, and sensation. Surprisingly, there are not as yet adequate monitoring systems to predict the onset and/or progression of HIV infection of the CNS. Neurological, neuropsychological, CSF, and magnetic resonance imaging (MRI) analyses cannot accurately detect mental deterioration during advancing HIV disease. Reports suggest that in vivo proton MR spectroscopy (1H MRS) of the brain could be a predictor of virus-induced neurological deterioration. H MRS can measure N-acetylaspartate (NAA), a metabolite present only in neurons. Decreased NAA reflects neuronal loss seen during HIV infection of brain. To uncover possible associations between NAA levels and HIV-induced neurological disease we performed serial 1H MRS brain tests in HIV-infected patients with or at risk for encephalopathy. Serial testing, for 1 year, of 10 patients showed that brain NAA levels decreased in all HIV-infected subjects. The most severe NAA reductions were associated with progressive neurological impairment. These findings suggest that NAA can be used as a noninvasive measure of neuronal loss in patients with HIV disease. Most important, the results suggest that 1H MRS could be used to monitor therapeutics directed against HIV infection within the CNS.
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Affiliation(s)
- J R McConnell
- Department of Radiology, University of Nebraska Medical Center, Omaha 68198
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Wu JZ, Chu WK. Anisotropy of the transport critical current in (110)-, (113)-, and a-axis-oriented YBa2Cu3O7- delta thin films. Phys Rev B Condens Matter 1994; 49:1381-1386. [PMID: 10010449 DOI: 10.1103/physrevb.49.1381] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Wu JZ, Yu N, Chu WK. Anisotropy of the ion-beam radiation effect in YBa2Cu3O7- delta (110) thin films. Phys Rev B Condens Matter 1993; 48:9929-9931. [PMID: 10007262 DOI: 10.1103/physrevb.48.9929] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Abstract
BACKGROUND The treatment of primary and recurrent skull base meningiomas presents a formidable surgical problem. METHODS Fifteen patients with primary and recurrent skull base meningiomas were treated by means of interstitial irradiation with iodine 125 (125I) seed implantation. The physical characteristics of 125I enabled the authors to administer a minimum tumor dose ranging from 100 to 500 Gy at a low dose rate of 0.05-0.25 Gy per hour. RESULTS All 15 patients are alive at a median follow-up of 29 months. Of the 15 patients, 2 with calcification and 2 without calcification achieved only partial responses. The remaining 11 patients achieved a complete response. No early or late complications were observed. CONCLUSIONS From these data, the authors conclude that interstitial irradiation with 125I seeds is an effective, safe, and simple method in the treatment of both recurrent and primary skull base meningiomas.
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Affiliation(s)
- P P Kumar
- Division of Radiation Oncology, University of Nebraska, Medical Center, Omaha
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Kumar PP, Patil AA, Leibrock LG, Chu WK, Syh HW, McCaul GF, Reeves MA. Continuous low dose rate brachytherapy with high activity iodine-125 seeds in the management of meningiomas. Int J Radiat Oncol Biol Phys 1993; 25:325-8. [PMID: 8420881 DOI: 10.1016/0360-3016(93)90355-y] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The purpose of this study was to evaluate if meningiomas can be effectively treated with brachytherapy using permanent implantation of high activity I-125 seeds. Thirteen patients with intracranial meningiomas were treated by means of permanent stereotactic implantation of one or more high-activity I-125 seeds. The physical characteristics of I-125 enabled us to deliver a minimum tumor dose ranging from 100 Gy to 500 Gy at a low dose rate of 5 cGy to 25 cGy per hr. Indications for this procedure included recurrence after initial surgery or as primary modality of treatment in patients who were not candidates for surgery. All 13 patients are alive at a median follow-up of 25 months. Nine of 13 patients achieved complete resolution of the tumor and in the remaining four, more than 50% reduction in tumor volume was noted at the last follow-up. No late complications were observed. We conclude from this initial data that localized high dose irradiation delivered at a low dose rate using I-125 permanent implantation is an effective, safe, and simple method in the treatment of both recurrent and primary intracranial meningiomas.
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Affiliation(s)
- P P Kumar
- Division of Radiation Oncology, University of Nebraska Medical Center, Omaha 68198-1045
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Abstract
The purposes of this study were to 1) determine the effect of concentric isokinetic training on strength and cross-sectional area (CSA) of selected extensor and flexor muscles of the forearm and leg, 2) examine the potential for preferential hypertrophy of individual muscles within a muscle group, 3) identify the location (proximal, middle, or distal level) of hypertrophy within an individual muscle, and 4) determine the effect of unilateral concentric isokinetic training on strength and hypertrophy of the contralateral limbs. Thirteen untrained male college students [mean age 25.1 +/- 6.1 (SD) yr] volunteered to perform six sets of 10 repetitions of extension and flexion of the nondominant limbs three times per week for 8 wk, using a Cybex II isokinetic dynamometer. Pretraining and posttraining peak torque and muscle CSA measurements for both the dominant and nondominant limbs were determined utilizing a Cybex II isokinetic dynamometer and magnetic resonance imaging scanner, respectively. The results indicated significant (P less than 0.0008) hypertrophy in all trained muscle groups as well as preferential hypertrophy of individual muscles and at specific levels. None of the muscles of the contralateral limbs increased significantly in CSA. In addition, significant (P less than 0.0008) increases in peak torque occurred for trained forearm extension and flexion as well as trained leg flexion. There were no significant increases in peak torque, however, for trained leg extension or for any movement in the contralateral limbs. These data suggest that concentric isokinetic training results in significant strength and hypertrophic responses in the trained limbs.
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Affiliation(s)
- D J Housh
- Department of Oral Biology, College of Dentistry, University of Nebraska Medical Center, Lincoln 68583-0740
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Syh HW, Chu WK, Kumar PP, Goede MR, Smith CL, Reeves MA, McCaul G. Estimation of the mean effective organ doses for total body irradiation from Rando phantom measurements. Med Dosim 1992; 17:103-6. [PMID: 1616588 DOI: 10.1016/0958-3947(92)90022-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
For the total body irradiation (TBI) procedure, it is necessary to compare the mean dose obtained from the tissue or organs and the estimated dose equivalent value from the computer program. Due to the easy-access of the Rando phantom and repeatability of TLDs and its output, the results from the experiment are quite encouraging for the verification of the dose distributions from total body irradiation at the given prescribed monitor units. The estimation of effective dose equivalent particularly across the lung sections was studied by combinations of using arms as the scatter volume to compensate for the inhomogeneity across the breast portion, as well as using the spoiler for skin-sparing purposes. The results were based upon various beam quality such as 4 MV, 6 MV, and 10 MV X rays. One series of experiments performed for this survey to ascertain the dose equivalent of the tissues was conducted. This paper describes the method and procedure for comparison between the measured data and computed data as a reference in the dosimetry of total body irradiation. Comparison of the measured and computed data for the largest collimated field shows that the calculated dose rates do not differ by more than 2% from the measured data. Because uncertainty is inherent in non-patient-like phantoms, the calculated data may be served as a reference for the dosimetry. For the total body irradiation setup, considering the radiation field size and treatment distances commonly employed, we conclude that the best combination of the patient setup will be (1) laying both arms down as compensation for lung inhomogeneity, and (2) the spoiler, which is made of acrylic about 8 mm thick and functions like a bolus, is needed to reduce the skin sparing effects and contribute the uniform dose distribution. The beam spoiler with the frame stands near the patient during the treatment.
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Affiliation(s)
- H W Syh
- Radiation Oncology, University of Nebraska Medical Center, Omaha 68198-1045
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Wu JZ, Hsieh PY, McGuire AV, Schmidt DL, Wood LT, Shen Y, Chu WK. Anisotropic properties of the high-quality epitaxial YBa2Cu3O7- delta (110) thin film. Phys Rev B Condens Matter 1991; 44:12643-12646. [PMID: 9999439 DOI: 10.1103/physrevb.44.12643] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Kumar PP, Patil AA, Leibrock LG, Chu WK, Syh J, McCaul GF, Reeves MA. Brachytherapy: a viable alternative in the management of basal meningiomas. Neurosurgery 1991; 29:676-80. [PMID: 1961396] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Thirteen patients with intracranial meningiomas of the skull base were treated with one or more high-activity iodine-125 seeds. In 11 patients, the seeds were implanted stereotactically under local anesthesia. A minimum dose of 100 to 500 Gy was delivered to the tumor at a dose rate of 5 to 25 cGy/h. Indications for this procedure included recurrence after initial surgery or as the primary modality of treatment in patients who were not candidates for surgery. All 13 patients are alive at a median follow-up of 15 months. Nine of 11 patients (82%) without calcification in their meningiomas achieved complete response. The remaining 4 patients-2 with calcification and 2 without--achieved partial response. No early or late complications were observed. We conclude from our experience that both recurrent and primary meningiomas of the skull base can be treated effectively with permanent iodine-125 brachytherapy.
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Affiliation(s)
- P P Kumar
- Division of Radiation Oncology, University of Nebraska Medical Center, Omaha
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28
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Wu JZ, Ting CS, Chu WK, Yao XX. Proximity effect on the superconducting transition temperature of YBa2Cu3O7-x/PrBa2Cu3O7-x superlattices. Phys Rev B Condens Matter 1991; 44:411-414. [PMID: 9998264 DOI: 10.1103/physrevb.44.411] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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29
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Chu WK, Allen WR, Picraux ST, Ellison JA. Planar channeling in superlattices. III. Potential and parameter dependence of catastrophic dechanneling. Phys Rev B Condens Matter 1990; 42:5923-5935. [PMID: 9994666 DOI: 10.1103/physrevb.42.5923] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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30
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McConnell JR, Fleming WH, Chu WK, Hahn FJ, Sarafian LB, Hofschire PJ, Kugler JD. Magnetic resonance imaging of the brain in infants and children before and after cardiac surgery. A prospective study. Am J Dis Child 1990; 144:374-8. [PMID: 2305749 DOI: 10.1001/archpedi.1990.02150270124041] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
We assessed the morphologic findings of the brain prospectively before and after cardiac surgery using magnetic resonance imaging. There were 12 patients with acyanotic and 6 with cyanotic heart disease. There were 2 deaths, and 1 patient did not have to undergo postoperative magnetic resonance imaging. The study group consisted of 15 patients completing both the preoperative and postoperative magnetic resonance imagings. All patients in the study group underwent moderate hypothermic cardiopulmonary bypass using a nonpulsatile membrane oxygenator. The mean (+/- SD) cardiopulmonary bypass time was 100 +/- 55 minutes. Ten of the preoperative studies were interpreted as normal. One third (5 of 15) of the patients showed ventriculomegaly and dilatation of the subarachnoid spaces on preoperative magnetic resonance images. Measurements of the preoperative and postoperative magnetic resonance images showed a postoperative increase in the bicaudate and third ventricular diameters. Four patients in the study group developed postoperative subdural hematomas. The subdural hematomas were small and caused no demonstrable mass effect on magnetic resonance imaging. One patient had a preoperative white matter infarction. There was 1 patient with a postoperative infarction.
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Affiliation(s)
- J R McConnell
- Department of Radiology, University of Nebraska Medical Center, Omaha 68105
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31
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Abstract
Decreasing or alleviating pain experienced by some patients during or after temporomandibular arthrography would make this relatively inexpensive and highly accurate technique more attractive. This is particularly true for those patients without access to MR or those whose referring physicians prefer arthrography to other techniques for diagnosing internal derangements. Ionic and nonionic contrast agents were compared in a randomized, double-blind trial to determine if pain could be decreased by using a nonionic contrast material. Forty patients received either Omnipaque 300 (nonionic, iohexol) or Hypaque 60 (ionic, diatrizoate meglumine). Radiographs were assessed for diagnostic quality, and patients were asked to note their level of discomfort. No significant differences between the agents were detected. Maximal discomfort was noted at 24 hr. Discomfort was classified as none, mild, or moderate, with no patients describing marked discomfort. This study does not support the use of nonionic contrast agents over the less expensive ionic agents for decreasing pain or improving film quality in temporomandibular joint arthrography.
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Affiliation(s)
- P A Kaplan
- Department of Radiology, University of Nebraska Medical Center, Omaha 68105
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32
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Taylor TK, Chu WK, Teten S. Tracking radiation for quality's sake. Adm Radiol 1989; 8:115-7. [PMID: 10296509] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
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33
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Allen WR, Chu WK, Picraux ST, Biefeld RM, Ellison JA. Planar channeling in superlattices: Resonance channeling. Phys Rev B 1989; 39:3954-3958. [PMID: 9948729 DOI: 10.1103/physrevb.39.3954] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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34
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Picraux ST, Biefeld RM, Allen WR, Chu WK, Ellison JA. Planar channeling in superlattices. II. Catastrophic dechanneling. Phys Rev B Condens Matter 1988; 38:11086-11097. [PMID: 9945981 DOI: 10.1103/physrevb.38.11086] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/11/2023]
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Hahn FJ, Chu WK, Coleman PE, Anderson JC, Dobry CA, Imray TJ, Hahn PY, Lee SH. Artifacts and diagnostic pitfalls on magnetic resonance imaging: a clinical review. Radiol Clin North Am 1988; 26:717-35. [PMID: 3380943] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
High field MRI of the brain occasionally exhibits imaging artifacts; most artifacts are obvious and easily recognized, but some are subtle and mimic disease. A thorough understanding of brain MRI artifacts is important to avoid potential diagnostic pitfalls. Some imaging techniques or procedures could be utilized to remove or identify artifacts. These include additional projections, different pulse sequence, and 90 degree shift of phase-encoding gradient. The use of respiratory gating or cardiac gating may also improve image quality by reducing some of the motion-related artifacts.
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Affiliation(s)
- F J Hahn
- Department of Radiology, University of Nebraska School of Medicine, Omaha
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36
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Taylor TK, Chu WK. Microcomputers in radiation oncology. Adm Radiol 1987; 6:22-5. [PMID: 10284779] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
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38
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Temme JB, Chu WK, Anderson JC. CT scanograms compared with conventional orthoroentgenograms in long bone measurement. Radiol Technol 1987; 59:65-8. [PMID: 3659341] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
In this article the standard orthoroentgenograph is compared with computed tomography (CT) scanography in determining bone length discrepancies. Dried femur bones are studied by both methods. The CT scanogram method is found to be more accurate than the orthoroentgenography method.
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Affiliation(s)
- J B Temme
- Division of Radiologic Technology, School of Allied Health Professions, University of Nebraska Medical Center, Omaha 68105
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Huurman WW, Jacobsen FS, Anderson JC, Chu WK. Limb-length discrepancy measured with computerized axial tomographic equipment. J Bone Joint Surg Am 1987; 69:699-705. [PMID: 3597470] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
A simple, rapid, and accurate method for measuring limb-length discrepancies with computerized axial tomographic equipment is described. With this method less irradiation is delivered and some of the errors of computation are eliminated, compared with conventional methods. The costs of the technique are comparable with those of scanograms. The method is particularly applicable in the patient who has contracture of a joint.
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Chu WK, Sangster W. Potential impacts of MRI accidents. Radiol Technol 1986; 58:139-41. [PMID: 3786695] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
A minor accident occurred in our Magnetic Resonance imaging suite. It is minor, because no personal injury nor equipment damage resulted from it. However, this incident has prompted us to review and re-emphasize our safety precautions and to investigate means of insurance coverage for any potential effects that could result from such incidents.
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Kumar PP, Good RR, Skultety FM, Jones EO, Chu WK. Retreatment of recurrent cystic craniopharyngioma with chromic phosphorus P 32. J Natl Med Assoc 1986; 78:542-3, 547-9. [PMID: 3735454 PMCID: PMC2571306] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
A cystic craniopharyngioma in a two-year-old boy recurred six months after surgery and postoperative external-beam radiotherapy. Successful retreatment was accomplished with radioisotope injection of 0.5 mCi of chromic phosphorus P 32 into the intracranial cyst, which delivered approximately 300.00 Gy to the cyst wall. The patient's symptoms were relieved, and he is without evidence of disease or cystic fluid accumulation four years after intracavitary (32)P irradiation.
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Kumar PP, Good RR, Hodgson PE, Edney JA, Jones EO, Chu WK, McAnulty BE, Dunlap B, Rogers SS, McCaul GF. Intraoperative electron-beam facility at the University of Nebraska Medical Center. Nebr Med J 1986; 71:191-8. [PMID: 3724916] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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44
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Picraux ST, Allen WR, Biefeld RM, Ellison JA, Chu WK. Incident-angle dependence of catastrophic dechanneling for strained-layer superlattices. Phys Rev Lett 1985; 54:2355-2358. [PMID: 10031319 DOI: 10.1103/physrevlett.54.2355] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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45
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Pan CK, Zheng DC, Finstad TG, Chu WK, Speriosu VS, Nicolet MA, Barrett JH. Structural study of GaSb/AlSb strained-layer superlattice. Phys Rev B Condens Matter 1985; 31:1270-1277. [PMID: 9935901 DOI: 10.1103/physrevb.31.1270] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/11/2023]
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Hahn FJ, Chu WK, Cheung JY. CT measurements of cranial growth: alternative measurement method. AJNR Am J Neuroradiol 1985; 6:537-8. [PMID: 3927669 PMCID: PMC8335186] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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Abstract
Newer CT scans have greatly enhanced oculometric research and made it possible to measure ocular dimensions. With these measurements, ocular volume can be more accurately estimated to understand its relationship with age and sex. One hundred CT orbit scans with presumed normal eyes were used for the data base. The mean values and normal variations of ocular volumes at various ages in both sexes are presented. Rapid growth of the eyeball was noted during the first 24 months of age. It reached its peak between the ages of 18 and 30 years of age, after which there was a reduction. Results may be of help in recognizing eye abnormalities such as microophthalmus and macrophthalmia.
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Chu WK, Dobry CA, Imasy TJ, Taylor TK. Comprehensive radiological equipment management program. J Clin Eng 1984; 9:281-9. [PMID: 10269779 DOI: 10.1097/00004669-198410000-00002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The increasing cost and complexity of state-of-the-art radiological equipment, and the need for more comprehensive safety and performance assurance, have increased maintenance expenditures to a level where they have become one of the largest operating expenses of radiology departments. To cope with this ever increasing expenditure, a comprehensive in-house maintenance program was implemented in our institution. This program properly balanced the capability of the radiology department's in-house technical personnel with support provided by equipment manufacturers' service organizations. Quality assurance activities are also included as an integral part of the entire program. Since the implementation of the program, an average 40% reduction in the annual maintenance expenditure has been observed.
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Abstract
Growth patterns of the cranium measured directly as head circumference have been well documented. With the availability of computed tomography (CT), cranial dimensions can be obtained easily. The objective of this project was to establish the mean values and their normal variance of CT cranial area of subjects at different ages. Cranial areas and its long and short axes were measured on CT scans for 215 neurologic patients of a wide age range who presented no evidence of abnormal growth of head size. Growth patterns of the cranial area as well as the numeric product of its linear dimensions were determined via a curve fitting process. The patterns resemble that of the head circumference growth chart, with the most rapid growth observed in the first 12 months of age and reaching full size during adolescence. It is believed that the availability of such reference, in addition to the head circumference measurement, will be valuable to the CT reviewer in determining the growth status of head size.
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50
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Hahn FJ, Chu WK, Torkelson RD. CT measurements of cranial growth: microcephaly. AJR Am J Roentgenol 1984; 142:1257-8. [PMID: 6609617 DOI: 10.2214/ajr.142.6.1257] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Computed tomographic (CT) head scans were measured to determine the cranial dimensions of four children with microcephaly. These measurements were compared with cranial dimensions of normal children. CT proved to be useful in determining the developmental status of children with neurologic problems relative to their normal counterparts on the basis of cranial dimensions.
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