| This course will focus on the definition and determination of dosimetry quantities and units used for radiation protection of patients undergoing x-ray procedures, both diagnostic and interventional. It will present and discuss ICRP terms such as effective dose as well as ICRU-recommended magnitudes such as incident or entrance air-kerma for radiography/fluoroscopy, and air-kerma (or dose) index, air-kerma (or dose) length-product, and more recently, size-specific dose estimate for computed tomography. Differences and uncertainties associated with effective doses, dose indices and patient organ doses will be examined. Current methods of organ dose determinations, like placing external dosimeters such as TLD or OSL on the patient’s skin, making measurements in patient-mimicking physical phantoms, and performing Monte Carlo radiation transport calculations using mathematical simulations, will be illustrated. The question is whether we need individualized dosimetry to assess patient risk or whether the goal is to optimize patient radiological protection. If the goal is not to assess risk, but to reduce it, dose-related machine parameters can be measured easily and compared against previously established diagnostic reference levels (DRLs). Published DRLs for several imaging modalities will be reviewed. The course will end with an introduction to the DICOM standards, especially the Radiation Dose Structured Report (RDSR), and its potential impact on patient dose management in radiological procedures. |
