Computing patient doses of X-ray examinations using a patient size- and sex-adjustable phantom.

Both the use of traditional fluoroscopy and the increasing use of modern digital techniques in radiology and interventional radiology demand the development of versatile computer programs for patient dose determinations. Long computing times restrict the use of Monte Carlo (MC) methods in dose monitoring applications where the radiological views change frequently. In the Organ Doses Calculation Software application (ODS-60), the phantom model is similar in principle to the Alderson-Rando (A-R) phantom, but its sex, size and shape is modified according to a particular patient. Organ and effective doses are computed online (in a few seconds) using a method similar to the traditional dose planning systems used in radiotherapy. In this paper, the new ODS-60 software is presented in detail and its capabilities are demonstrated. Software performance was determined by comparing the results with those from independent methods. In the case of a reference man-sized male, the effective dose was about 7% larger than the effective dose given in another publication. In the case of a reference woman-sized female, the disagreement with the other method was greater (33%). Anatomical differences between the phantom models (ODS-60 and MC) were found to be the main reasons for these findings. This paper shows the advantage of using a patient size- and sex-adaptable phantom for patient dose determinations; the conversion coefficient from entrance surface dose-to-effective dose ratio between male (170 cm, 85 kg) and a female (160 cm, 43 kg) varies in the range 1.5-2.

Intercomparison of radiotherapy treatment planning systems for external photon and electron beam dose calculations.

Dose distributions calculated by six different treatment planning systems (TPSs), used by the hospitals in Finland or in Russia, were compared with measured dose distributions. Five typical cases of irradiation were selected: regular fields, oblique incidence, irregular field, wedge field and inhomogeneity in a water equivalent phantom. The beam data for each TPS where those pertaining to the beam where the comparative relative measurements were performed. The results indicate that the dose distributions produced by different TPSs can differ from each other as well as from the measured dose distributions up to a level which is not acceptable in terms of the ICRU recommendations. Greatest differences seem to be related to the omission or undue consideration of the scatter components of the beam.