Characterization of the scattered radiation field around an x-ray tube

Abstract

To determine patient doses or doses to the medical staff, Monte Carlo calculations are frequently applied. In these kinds of calculations the x-ray tube is often simplified to make the calculations faster. The purpose of this study is to investigate the influence of simplifications in the Monte Carlo set-up of the x-ray tube on the observed differences between measurements and calculations in the scattered field. At a distance of 50 and 100 cm from the focal spot, air kerma calculations are done for different angles from -90° to 90° from the central beam axis in steps of 15° with the Monte Carlo software code MCNP-X. Different calculations were performed where each time a component of the simulated x-ray tube (collimator, filters, etc) or the environment (walls) is included. Scattered doses are also measured with thermoluminescent dosemeters. For the most simplified geometry of the x-ray tube, measurements are on average 70% larger than the calculated results. A much better agreement with the measurements is observed for more realistic calculations. The current work applies to a particular source in the SCK•CEN calibration laboratory; therefore the obtained results are representative and relevant for studies in calibration laboratories. As clinical sources have more shielding material and as in real imaging situations the scatter generated at the patient is much larger than the scatter leaking from the source, the results of this study have a limited impact on the wider field of clinical dosimetry.

Ensuring the unity of measurements of the neutron radiation rate absorbed dose in the field of clinical neutron radiation dosimetry

“…If the value of the absorbed dose received by the patient is less than necessary, then some of the malignant cells will not be destroyed. If the value of the absorbed dose received by the patient exceeds the specified value, then ionizing radiation will harm healthy tissues, thereby aggravating the patient's condition [6]. This causes very high demands on the accuracy of measurements of the absorbed dose of neutron radiation in medical practice and on the system for ensuring the uniformity of measurements of these measurements.…”

High frequency residues: A new set of signals for detectability studies of an X-ray imaging system

“…Several studies have described methods to properly design the necessary protections [1,16,12,18], and some of them have been incorporated into international and national recommendations [11], enabling the design of nearly any medical X-ray installation today. At all times, new methods are being developed to facilitate the design of shielding for various facilities, such as dental radiology rooms [19], mammography suites [15], and those allowing for a better description of the protective materials used in radiology [3,4,9] and interventional procedures [10,17].…”

Technical Note: Assessment of scatter originating from the x‐ray tube collimator assembly of modern angiography systems

“…In 2004, McVey et al used Monte Carlo simulation to estimate scatter originating from within a simulated air kerma‐area product (KAP) meter . In 2011, Struelens et al studied scatter originating from Cu and Al spectral filters and collimators and concluded that “the largest contribution of the exposure of medical staff comes from scattered radiation from the patient” . However, that work did not include a physical KAP meter.…”

“…11 In 2011, Struelens et al studied scatter originating from Cu and Al spectral filters and collimators and concluded that "the largest contribution of the exposure of medical staff comes from scattered radiation from the patient". 12 However, that work did not include a physical KAP meter. In 2017, Miyagawa et al investigated a lead-lined collimator assembly cover as a means to reduce scattered radiation to the operator from modern x-ray angiography systems.…”

“…Therefore, in keeping with the goal of striving to use ALARA levels of radiation, the aim of this work was to characterize the potential contribution of modern x‐ray angiography system collimator assemblies to radiation scatter. A secondary goal was to investigate a potential collimator assembly scatter mitigation strategy similar to that described by Miyagawa et al…”