title: Measurement of radiation dose in cerebral CT perfusion study.
abstract: OBJECTIVE
  To evaluate radiation dose in cerebral perfusion studies with a multi-detector row CT (MDCT) scanner on various voltage and current settings by using a human head phantom.
  
  
  METHODS
  Following the CT perfusion study protocol, continuous cine scans (1 sec/rotation x60 sec) consisting of four 5-mm-thick contiguous slices were performed three times at variable tube voltages of 80 kV, 100 kV, 120 kV, and 140 kV with the same tube current setting of 200 mA and on variable current settings of 50 mA, 100 mA, 150 mA, and 200 mA with the same tube voltage of 80 kV. Radiation doses were measured using a total of 41 theroluminescent dosimeters (TLDs) placed in the human head phantom. Thirty-six TLDs were inside and three were on the surface of the slice of the X-ray beam center, and two were placed on the surface 3 cm caudal assuming the lens position.
  
  
  RESULTS
  Average radiation doses of surface, inside, and lens increased in proportion to the increases of tube voltage and tube current. The lowest inside dose was 87.6+/-15.3 mGy, and the lowest surface dose was 162.5+/-6.7 mGy at settings of 80 kV and 50 mA. The highest inside dose was 1,591.5+/-179.7 mGy, and the highest surface dose was 2,264.6+/-123.7 mGy at 140 kV-200 mA. At 80 kV-50 mA, the average radiation dose of lens was the lowest at 5.5+/-0.0 mGy. At 140 kV-200 mA the radiation dose of lens was the highest at 127.2+/-0.6 mGy.
  
  
  CONCLUSIONS
  In cerebral CT perfusion study, radiation dose can vary considerably. Awareness of the patient's radiation dose is recommended.
authors.affiliation: Department of Radiology, Ehime University School of Medicine, Shitsukawa, Toon, Japan.
authors.forename: Masaaki
authors.initials: M
authors.lastname: Hirata
authors.forename: Yoshifumi
authors.initials: Y
authors.lastname: Sugawara
authors.forename: Yukimi
authors.initials: Y
authors.lastname: Fukutomi
authors.forename: Kenji
authors.initials: K
authors.lastname: Oomoto
authors.forename: Kenya
authors.initials: K
authors.lastname: Murase
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Miki
authors.forename: Teruhito
authors.initials: T
authors.lastname: Mochizuki
mesh_terms: D001479:Basal Ganglia / Q000528:radiation effects; D001921:Brain / Q000000981:diagnostic imaging* / Q000528:radiation effects; D002933:Cineradiography; D005625:Frontal Lobe / Q000528:radiation effects; D006257:Head / Q000528:radiation effects; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D007908:Lens, Crystalline / Q000528:radiation effects; D009778:Occipital Lobe / Q000528:radiation effects; D019047:Phantoms, Imaging; D011829:Radiation Dosage; D013819:Thermoluminescent Dosimetry / Q000295:instrumentation; D014057:Tomography, X-Ray Computed / Q000379:methods*