Radiation Protection Dosimetry Advance Access published online on May 3, 2008
Radiation Protection Dosimetry, doi:10.1093/rpd/ncn159
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ASSESSMENT OF PATIENT ORGAN DOSE IN CT VIRTUAL COLONOSCOPY FOR BOWEL CANCER SCREENING
1 Referenzzentrum Mammographie Süd West am, Universitätsklinikum Gießen und Marburg am Standort Marburg TQS, Dipl.-Ing. St. Schopphoven Bahnhofstraße 7, 35037 Marburg, Germany
2 Quality Assurance Reference Centre, Unit 9, Kingfisher Way, Silverlink, Wallsend, Tyne and Wear NE28 9ND, UK
3 Department of Radiology, Brüder Krankenhaus, Nordallee 1, Trier, Germany
* Corresponding author: schopphoven{at}referenzzentrum-suedwest.de
Justification and optimisation form the basic elements for the radiological protection of individuals for medical exposures. Justification includes the assessment of patient organ doses from which radiation risks are deduced. Medical radiation exposures are justified only in the case of a sufficient net benefit. For screening examinations, such as CT virtual colonoscopy, this implies that patient organ doses should be relatively low to minimise the radiation detriment. Image quality should be sufficient to maximise the potential diagnostic benefits. The Medical Exposures Directive places special attention on medical exposures as part of health screening programmes and examinations involving high individual doses to the patient, both of which apply to CT virtual colonoscopy. Technical factors were recorded for a series of patients having virtual colonoscopy on a CT scanner. In addition, the dose–length product was assessed. Patient organ doses were deduced using a CT dose calculation program. The typical effective dose was 7.5 mSv for male patients and 10.2 mSv for female patients. The effective dose is higher for female patients, as some gender-specific organs are irradiated during virtual colonoscopy. Each patient has two series of scans resulting in doses of 15 mSv for male patients and 20 mSv for female patients.