title: A study on the usefulness of methylcellulose in rectal CT based on the analysis of the differences in absorption of radiation-permeable and radiation-impermeable materials.
abstract: OBJECTIVE
  The purpose of this study was to use various radiation-permeable and radiation-impermeable materials, used to facilitate the observation of a lesion during a rectal computed tomography (CT) scan, in order to determine the best material to use.
  
  
  METHODS
  In regard to the study method, the radiation-permeable and radiation-impermeable materials of physiological saline, methylcellulose, contrast medium, ultrasound gel, and air were used to perform scanning with scan parameters that were used in general abdominal scanning. The GSI mode was used for material analysis.
  
  
  RESULTS
  According to the results of the phantom study, the average CT value was 25.5 ± 5.9 HU for physiological saline, 77.6 ± 7.3 HU for methylcellulose, 3,070 ± 0.1 HU for contrast medium, 74.1 ± 11.9 HU for ultrasound gel, and -954.1 ± 10.3 HU for air. According to the analysis of materials by energy, contrast medium and physiological saline showed a dramatic decrease in the CT value as energy increased. Methylcellulose showed a gradual decrease in CT value, whereas air showed a small change in CT value according to the graph.
  
  
  CONCLUSIONS
  Out of these materials, methylcellulose had the advantage of reducing discomfort in patients, and was more convenient for examiners before and after the rectal CT scan.
authors.affiliation: Department of International Radiological Science, Hallym University of Graduate Studies, Seoul, Republic of Korea, 8452404@hanmail.net.
authors.forename: Jae-Hwan
authors.initials: JH
authors.lastname: Cho
authors.forename: Hae-Kag
authors.initials: HK
authors.lastname: Lee
authors.forename: Hyun-Ju
authors.initials: HJ
authors.lastname: Kim
authors.forename: Yeong-Cheol
authors.initials: YC
authors.lastname: Heo
authors.forename: Jin-Hyeok
authors.initials: JH
authors.lastname: Lee
authors.forename: In-Sik
authors.initials: IS
authors.lastname: Hong
mesh_terms: D000388:Air; D003287:Contrast Media; D005782:Gels; D006801:Humans; D008747:Methylcellulose; D019047:Phantoms, Imaging; D011829:Radiation Dosage; D011856:Radiographic Image Enhancement / Q000379:methods; D012007:Rectum / Q000000981:diagnostic imaging; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D003287:Contrast Media; D005782:Gels; D008747:Methylcellulose