Purpose: To assess the frequency, appropriateness, and radiation doses associated with multiphase computed tomography (CT) protocols for routine chest and abdomen–pelvis examinations in 18 countries. Materials and Methods: In collaboration with the International Atomic Energy Agency, multi-institutional data on clinical indications, number of scan phases, scan parameters, and radiation dose descriptors (CT dose–index volume; dose–length product [DLP]) were collected for routine chest (n = 1706 patients) and abdomen–pelvis (n = 426 patients) CT from 18 institutions in Asia, Africa, and Europe. Two radiologists scored the need for each phase based on clinical indications (1 = not indicated, 2 = probably indicated, 3 = indicated). We surveyed 11 institutions for their practice regarding single-phase and multiphase CT examinations. Data were analyzed with the Student t test. Results: Most institutions use multiphase protocols for routine chest (10/18 institutions) and routine abdomen–pelvis (10/11 institutions that supplied data for abdomen–pelvis) CT examinations. Most institutions (10/11) do not modify scan parameters between different scan phases. Respective total DLP for 1-, 2-, and 3-phase routine chest CT was 272, 518, and 820 mGy·cm, respectively. Corresponding values for 1- to 5-phase routine abdomen–pelvis CT were 400, 726, 1218, 1214, and 1458 mGy cm, respectively. For multiphase CT protocols, there were no differences in scan parameters and radiation doses between different phases for either chest or abdomen–pelvis CT ( P = 0.40-0.99). Multiphase CT examinations were unnecessary in 100% of routine chest CT and in 63% of routine abdomen–pelvis CT examinations. Conclusions: Multiphase scan protocols for the routine chest and abdomen–pelvis CT examinations are unnecessary, and their use increases radiation dose.

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IntroductionExternal photon beam modulation using compensators in order to achieve a desired dose distribution when brachytherapy treatment is followed by external beam radiation is a well-established technique. A compensator modulates the central part of the beam, and the dose beneath the thickest part of the compensator is delivered mostly by scattered, low energy photons. A two-dimensional detector with a good spatial resolution is needed for the verification of those beams. In this work, the influence of different types of detectors on the measured modulated dose distributions was examined.Materials and methodsDosimetric verification was performed using X-Omat V, Eastman Kodak radiographic films at different depths in a solid water phantom. The film measurements were compared with those made by ionization chambers. Photon beams were also modelled using EGSnrc Monte Carlo algorithm to explain the measured results.ResultsMonte Carlo calculated over-response of the film under the thickest part of the compensator was over 15%, which was confirmed by measurements. The magnitude of over-response could be associated with changes in the spectra of photon energy in the beam.ConclusionsThe radiographic film can be used for the dosimetry of compensated high energy photon beams, with limitations in volumes where photon spectra are hardly degraded.

Ma jor ity of health in sti tu tions in Croatia do not have med i cal phys i cists in di ag nos tic ra di ology. Re gard ing this, in the west re gion of Croatia col lab o ra tion be tween pub lic health in sti tution and Uni ver sity Hos pi tal Rijeka was ini ti ated in 2015. Qual ity As sur ance pro gram was im ple mented in these pub lic health in sti tu tions dur ing 2015 and 2016 and the next step was to as sess pa tient doses for the most fre quent X-ray ex am i nations. This in cluded five pub lic health in sti tu tions: 1 uni ver sity hos pi tal, 1 gen eral hos pi tal, 1 spe cial hos pi tal, 2 pub lic health in sti tu tions with 13 fa cil i ties. The aim of this study was to carry out as sess ment of pa tient doses and to es tab lish lo cal di ag nos tic ref er ence lev els of entrance sur face air kerma for ev ery in sti tu tion for six most fre quent X-ray ex am i na tions. Also, lo cal di ag nos tic ref er ence lev els for the whole west re gion of Croatia were es tab lished and com pared with the na tional di ag nos tic ref er ence lev els and lat est pub lished data. Me dian entrance sur face air kerma val ues for tho rax PA, tho rax LAT, cer vi cal spine AP, tho racic spine AP, lum bar spine AP, pel vis AP and si nuses are 0.14 mGy, 0.50 mGy, 0.52 mGy, 1.50 mGy, 2.52 mGy, 2.03 mGy, and 1.03 mGy, re spec tively. Di ag nos tic ref er ence lev els pro posed for our re gion were com pa ra ble with other stud ies.

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