Publications by authors named "Ying-Yan Chen"

Objectives: This study performed dosimetry studies and secondary cancer risk assessments on using electronic portal imaging device (EPID) and cone beam computed tomography (CBCT) as image guided tools for the early lung cancer patients treated with SBRT.

Methods: The imaging doses from MV-EPID and kV-CBCT of the Edge accelerator were retrospectively added to sixty-one SBRT treatment plans of early lung cancer patients. The MV-EPID imaging dose (6MV Photon beam) was calculated in Pinnacle TPS, and the kV-CBCT imaging dose was simulated and calculated by modeling of the kV energy beam in TPS using Pinnacle automatic modeling program.

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Article Synopsis
  • - The study investigates how different types of positioning errors in multi-leaf collimators (MLCs) affect the dosage delivered during stereotactic body radiotherapy (SBRT) for patients with early-stage lung cancer.
  • - Three types of MLC errors were simulated: random errors, systematic shifts (left or right), and opposite directional movements of MLC banks; dosimetric parameters and dose sensitivities were then calculated.
  • - Results showed that the dose sensitivities for MLC errors were significantly impacted by whether or not the MU (monitor units) were weighted, highlighting that larger patient volumes reduced dosage sensitivity, especially in automatic plans compared to manually optimized plans.
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Background: Streptococcus pneumoniae infections in Taiwan mostly occur in children aged 2-4 years. Because of a significant increase in the incidence of serotype 19A-related infections, the 13-valent pneumococcal conjugate vaccine (PCV13) was initially introduced in the national immunization program for children 2-5 years of age, prior to the national programs for infants. We have assessed the impact of such vaccination programs in reducing the incidence of invasive pneumococcal disease (IPD) in Taiwanese children.

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Introduction: Serotype replacement after the introduction of seven-valent pneumococcal conjugate vaccine (PCV7) and the future availability of multivalent PCVs prompted the listing of invasive pneumococcal disease (IPD) as a notifiable disease in Taiwan in October 2007. Here, we report the national surveillance results.

Methods: The study population comprised the whole nation of Taiwan from 2008 to 2012.

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In Taiwan, pertussis is a notifiable disease with a low incidence in recent years, and antimicrobial susceptibility testing for the causative agent, Bordetella pertussis, has not been reported to date. In May 2007, the Centers for Disease Control, Taiwan, was informed of a 1-month-old pertussis patient who did not respond to erythromycin treatment. In this study, we report the result of antimicrobial susceptibility testing performed for the suspected erythromycin-resistant isolate, as well as for an additional 27 B.

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Background And Purpose: Surveillance data of colonization by Haemophilus influenzae in Taiwan are lacking. This study aimed to define the nasopharyngeal carriage rate of H. influenzae among children younger than 5 years in northern Taiwan, and to determine the antibiotic susceptibility, serotype and the clonal relationship of these isolates.

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In this study, 830 Streptococcus pyogenes isolates collected between 2001 and 2002 from patients with scarlet fever in northern Taiwan were analyzed by M protein gene (emm) sequence typing, pulsed-field gel electrophoresis (PFGE), and antimicrobial susceptibility testing. A total of 21 emm types and 56 PFGE patterns were identified. The most frequent emm types were emm1 (29.

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In Taiwan, routine pertussis immunization has been implemented for more than 40 years and a low incidence of pertussis was maintained until an 80-fold increase in cases occurred in 1992. The unexpected increase emphasized the significance of pertussis. This study evaluated a total of 2452 reported cases of pertussis during 1993-2004 and surveillance data on incidence, age distribution and seasonality.

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A total of 522 Streptococcus pneumoniae invasive isolates from diverse sources were collected from January 2002 to December 2003 in Taiwan in order to understand the serotype distribution of invasive isolates in Taiwan. The most frequently isolated serotypes of S. pneumoniae were types 14 (18.

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Pertussis reemerges periodically despite high pertussis vaccination coverage in many countries. We used prn and fim3 gene sequences and pulsed-field gel electrophoresis (PFGE) to analyze the molecular epidemiology of 168 clinical isolates of Bordetella pertussis during 1993-2004, and deduced possible reasons for an outbreak in 1997 in Taiwan. In Taiwan, during 1996-1997, a shift of prn1 to prn2 was reflected in a transition of PFGE group I to group IIIa; during 2000-2001, the change from fim3A to fim3B was displayed in transition of PFGE group IIIa to group IIIb.

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Streptococcus pneumoniae causes substantial morbidity and mortality worldwide. Because only limited data are available for the antibiotic resistance patterns and seroepidemiology of invasive S. pneumoniae isolates in Taiwanese children, this national surveillance of invasive pneumococcal infections in children was conducted during a 5-year period.

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In recent studies, antigenic divergence has been observed in Bordetella pertussis circulating isolates. We collected 80 Bordetella pertussis isolates in Taiwan from 1998 to 2004 and analyzed them using a combination of pulsed-field gel electrophoresis (PFGE) and sequencing of the ptxS1 and prn genes. The incidence of pertussis increases every 3 years, and most of the isolates prevalent since 1998 have expressed nonvaccine ptxS1A and prn2 alleles.

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