title: Effects of quality assurance regulatory enforcement on performance of mammography systems: evidence from large-scale surveys in Taiwan.
abstract: OBJECTIVE
  The Standards for Medical Exposure Quality Assurance in mammography systems were enacted on July 1, 2008, in Taiwan. This study aimed to evaluate the trends in performance of mammography units before and after the regulation started on the basis of annual on-site surveys from 2008 to 2010.
  
  
  METHODS
  On-site measurements were conducted on 215, 205, and 209 mammography units in 2008, 2009, and 2010, respectively, which accounted for more than 95% of all units in Taiwan. Phantom image quality, average glandular dose (AGD), and half-value layer were evaluated on all systems. Processor conditions, compression conditions, radiation output, and computed radiography exposure indicators were assessed on units participating in mammography screening in 2008 and on all units in the later years. Evaluations of maximum compression force and automatic exposure control reproducibility were added into the protocol from 2009 onward.
  
  
  RESULTS
  Mean phantom scores were improved significantly from 2008 to 2009 (11.63 ± 1.30 vs 12.31 ± 0.94, p < 0.05) and remained stable for 2010 (12.35 ± 0.87). Mean AGDs were 1.48 ± 0.47, 1.38 ± 0.41, and 1.37 ± 0.42 mGy over the 3 years, with a significant reduction from 2008 to 2009 (p < 0.05). For film-screen mammography systems, variations of sensitometric curves were greatly reduced in 2009 and 2010 when compared with 2008. Passing rates were increased after the regulation took effect in almost all aspects.
  
  
  CONCLUSIONS
  Results from large-scale on-site surveys showed an overall improvement in performance after quality assurance in mammography was enforced in Taiwan.
authors.affiliation: Department of Medical Imaging and Intervention, Chang Gung Memorial Hospital at Linkou, 5 Fushing St, Kweishan, Taoyuan 333, Taiwan.
authors.forename: Yi-Shuan
authors.initials: YS
authors.lastname: Hwang
authors.forename: Hui-Yu
authors.initials: HY
authors.lastname: Tsai
authors.forename: Chien-Chuan
authors.initials: CC
authors.lastname: Chen
authors.forename: Pei-Kwei
authors.initials: PK
authors.lastname: Tsay
authors.forename: Huay-Ben
authors.initials: HB
authors.lastname: Pan
authors.forename: Giu-Cheng
authors.initials: GC
authors.lastname: Hsu
authors.forename: Jen-Hsuan
authors.initials: JH
authors.lastname: Lin
authors.forename: Chen-Shou
authors.initials: CS
authors.lastname: Chui
authors.forename: Yung-Liang
authors.initials: YL
authors.lastname: Wan
authors.forename: Ho-Ling
authors.initials: HL
authors.lastname: Liu
mesh_terms: D000704:Analysis of Variance; D001943:Breast Neoplasms / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D008327:Mammography / Q000592:standards*; D019047:Phantoms, Imaging; D011785:Quality Assurance, Health Care; D011829:Radiation Dosage; D015203:Reproducibility of Results; D013624:Taiwan