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

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Abstract
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.