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T Y Song

Publications and source records attributed to T Y Song.

5 recordsLinked to original sources
PubMed2004

GATE: a simulation toolkit for PET and SPECT.

Monte Carlo simulation is an essential tool in emission tomography that can assist in the design of new medical imaging devices, the optimization of acquisition protocols and the development or assessment of image reconstruction algorithms and correction techniques. GATE, the Geant4 Application for Tomographic Emission, encapsulates the Geant4 libraries to achieve a modular, versatile, scripted simulation toolkit adapted to the field of nuclear medicine. In particular, GATE allows the description of time-dependent phenomena such as source or detector movement, and source decay kinetics. This feature makes it possible to simulate time curves under realistic acquisition conditions and to test dynamic reconstruction algorithms. This paper gives a detailed description of the design and development of GATE by the OpenGATE collaboration, whose continuing objective is to improve, document and validate GATE by simulating commercially available imaging systems for PET and SPECT. Large effort is also invested in the ability and the flexibility to model novel detection systems or systems still under design. A public release of GATE licensed under the GNU Lesser General Public License can be downloaded at http:/www-lphe.epfl.ch/GATE/. Two benchmarks developed for PET and SPECT to test the installation of GATE and to serve as a tutorial for the users are presented. Extensive validation of the GATE simulation platform has been started, comparing simulations and measurements on commercially available acquisition systems. References to those results are listed. The future prospects towards the gridification of GATE and its extension to other domains such as dosimetry are also discussed.

Computer Simulation↗
PubMed2001

Inhibitory effects of Cassia tora L. on benzo[a]pyrene-mediated DNA damage toward HepG2 cells.

The effects of water extracts from Cassia tora L. (WECT) treated with different degrees of roasting on benzo[a]pyrene (B[a]P)-induced DNA damage in human hepatoma cell line HepG2 were investigated via the comet assay without exogenous activation mixtures, such as S9 mix. WECT alone, at concentrations of 0.1-2 mg/mL, showed neither cytotoxic nor genotoxic effect toward HepG2 cells. B[a]P-induced DNA damage in HepG2 cells could be reduced by WECT in a dose-dependent manner (P < 0.05). At a concentration of 1 mg/mL, the inhibitory effects of WECT on DNA damage were in the order unroasted (72%) > roasted at 150 degrees C (60%) > roasted at 250 degrees C (23%). Ethoxyresorufin-O-dealkylase activity of HepG2 cells was effectively inhibited by WECT, and a similar trend of inhibition was observed in the order unroasted (64%) > roasted at 150 degrees C (42%) > roasted at 250 degrees C (18%). The activity of NADPH cytochrome P-450 reductase was also decreased by unroasted and 150 degrees C-roasted samples (50% and 38%, respectively). Furthermore, glutathione S-transferase activity was increased by treatment with unroasted (1.26-fold) and 150 degrees C-roasted (1.35-fold) samples at 1 mg/mL. In addition, the contents of anthraquinones (AQs) in WECT, including chrysophanol, emodin, and rhein, were decreased with increasing roasting temperature. Each of these AQs also demonstrated significant antigenotoxic activity in the comet assay. The inhibitory effects of chrysophanol, emodin, and rhein on B[a]P-mediated DNA damage in HepG2 cells were 78, 86, and 71%, respectively, at 100 microM. These findings suggested that the decreased antigenotoxicity of the roasted samples might be due to a reduction in their AQs content.

Benzo(a)pyrene↗
PubMed1997

DNA cytometric proliferative index predicting organ confinement in clinical stage-B prostate cancer.

PURPOSE: To assess nuclear activity by DNA flow cytometry (FCM), Gleason score and serum prostate-specific antigen (PSA) levels in predicting extracapsular tumour involvement in patients with prostate cancer. DESIGN: Retrospective pathologic study. PATIENTS: Forty patients with clinical stage-B prostate cancer who underwent radical prostatectomy. INTERVENTIONS: The relationship between the pathologic state and each of the proliferative index (PI). Gleason score and PSA level was analysed retrospectively with the use of archival specimens. Preoperative serum PSA levels, were measured by the Hybritech assay. Gleason score was determined by 2 of the authors. Tumours were classified as stage B (confined to prostate), C1 (focal capsular penetration) or C2 (involvement of seminal vesicles or capsular perforation). FCM PI measurements were performed on deparaffinized tumour specimens. RESULTS: All 40 specimens were diploid. There were 9 pathologic stage-B, 16 stage-C1 and 15 stage-C2 tumours. The serum PSA level was 20 ng/mL or less for all patients except 2, for whom the levels were 27.8 ng/mL and 45.9 ng/mL, respectively. A Gleason score lower than 7 had a 76.0% sensitivity and 53.5% specificity in predicting organ confinement. In contrast, a PI of 21 or lower had a 84.0% sensitivity and a 73.0% specificity in predicting organ confinement, with a positive predictive value of 84.0%. Of the 17 tumours with both "favourable" features (Gleason score lower than 7 and PI of 21 or lower), only 1 (5.9%) had extracapsular involvement (stage C2). Of the 6 tumours with both "unfavourable" features (Gleason score higher than 7 and PI of 21 or higher) 5 of 6 were stage C2 and 1 was stage C1. CONCLUSION: The single most consistent predictor of organ confinement was PI alone.

Cell Division↗
PubMed1996

Management of vesical calculi: comparison of lithotripsy devices.

Although endoscopic lithotripsy of bladder stones has been well described and is widely practiced, comparison of the main modalities of mechanical, electrohydraulic, and ultrasonic lithotripsy is lacking. The exact role of these and other modalities such as the Swiss Lithoclast and extracorporeal shockwave lithotripsy is not clearly defined. The safety and efficacy of the various lithotripsy modalities available to treat bladder calculi were reviewed retrospectively over an 18-year period. A total of 106 patients were treated with some form of intracorporeal lithotripsy. In general, all devices proved to be effective with a low rate of complications. The addition of transurethral resection of the prostate to bladder stone management under the same anesthetic was also found to be a safe procedure for moderate benign prostatic hyperplasia. In summary, transurethral endoscopic lithotripsy is a safe and effective method of bladder stone management both alone and in combination with transurethral prostatectomy. All modalities of intracorporeal lithotripsy are effective; however, devices such as ultrasound lithotripters or the Swiss Lithoclast that utilize larger, rigid probes may be more efficient for patients with large or particularly hard vesical calculi.

Adolescent↗