title: A Randomized Controlled Trial about the Levels of Radiation Exposure Depends on the Use of Collimation C-arm Fluoroscopic-guided Medial Branch Block.
abstract: BACKGROUND
  C-arm fluoroscope has been widely used to promote more effective pain management; however, unwanted radiation exposure for operators is inevitable. We prospectively investigated the differences in radiation exposure related to collimation in Medial Branch Block (MBB).
  
  
  METHODS
  This study was a randomized controlled trial of 62 MBBs at L3, 4 and 5. After the patient was laid in the prone position on the operating table, MBB was conducted and only AP projections of the fluoroscope were used. Based on a concealed random number table, MBB was performed with (collimation group) and without (control group) collimation. The data on the patient's age, height, gender, laterality (right/left), radiation absorbed dose (RAD), exposure time, distance from the center of the field to the operator, and effective dose (ED) at the side of the table and at the operator's chest were collected. The brightness of the fluoroscopic image was evaluated with histogram in Photoshop.
  
  
  RESULTS
  There were no significant differences in age, height, weight, male to female ratio, laterality, time, distance and brightness of fluoroscopic image. The area of the fluoroscopic image with collimation was 67% of the conventional image. The RAD (29.9 ± 13.0, P = 0.001) and the ED at the left chest of the operators (0.53 ± 0.71, P = 0.042) and beside the table (5.69 ± 4.6, P = 0.025) in collimation group were lower than that of the control group (44.6 ± 19.0, 0.97 ± 0.92, and 9.53 ± 8.16), resepectively.
  
  
  CONCLUSIONS
  Collimation reduced radiation exposure and maintained the image quality. Therefore, the proper use of collimation will be beneficial to both patients and operators.
authors.affiliation: Department of Anesthesiology and Pain Medicine, Konkuk University Medical Center, Seoul, Korea.
authors.forename: Seung Woo
authors.initials: SW
authors.lastname: Baek
authors.forename: Jae Sung
authors.initials: JS
authors.lastname: Ryu
authors.forename: Cheol Hee
authors.initials: CH
authors.lastname: Jung
authors.forename: Joo Han
authors.initials: JH
authors.lastname: Lee
authors.forename: Won Kyoung
authors.initials: WK
authors.lastname: Kwon
authors.forename: Nam Sik
authors.initials: NS
authors.lastname: Woo
authors.forename: Hae Kyoung
authors.initials: HK
authors.lastname: Kim
authors.forename: Jae Hun
authors.initials: JH
authors.lastname: Kim
keywords: collimation; image quality; radiation absorbed dose; radiation exposure