Determination of Entrance Skin Doses and Organ Doses for Medical X Ray Examinations

Tung, Chuan–Jong; Cheng, C.Y.; Chao, Tsi-Chian; Tsai, Huei‐Ting

doi:10.1093/oxfordjournals.rpd.a032886

Cited by 7 publications

(2 citation statements)

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“…The BSF depends on factors such as kVp, field size, FFD, body tissue, etc. This quantity was studied previously by TLD measurements 17 and Monte Carlo simulations 18 for different x-ray radiographic procedures. Further, one may convert the ESD air into the entrance skin dose to tissue with backscatter (ESD tissue ) by the relation…”

Section: Methodsmentioning

confidence: 99%

Determination of guidance levels of dose for diagnostic radiography in Taiwan

Tung¹,

Tsai²,

Lo³

et al. 2001

Medical Physics

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The International Atomic Energy Agency has recommended guidance levels of dose for diagnostic radiography for a typical adult patient. These levels were intended to act as thresholds to trigger investigations or corrective actions in ensuring optimized protection of patients and maintaining appropriate levels of good practice. Since guidance levels should be derived from wide scale surveys of exposure factors performed in individual hospitals, a national survey was conducted recently in Taiwan to collect these factors for the most frequent radiographic procedures. A total of 276 completed questionnaires were received and analyzed. In the questionnaire, respondents were asked to check those projections that were routinely performed in their department and to report machine data, patient data, output measurements, and technical factors including kVp, mAs, focus-to-film distance, table-to-film distance, aluminum filtration, and focal spot size. Based on the survey data, entrance skin exposures in air, i.e., free air exposures at the point of intersection of the x-ray central beam with the entrance surface of the patient, were estimated using the RADCOMP program. Entrance surface doses to air and tissue with backscatter were then evaluated by the application of the exposure-dose conversion factor and the backscatter factor obtained from TLD measurements and Monte Carlo simulations. Guidance levels were determined from survey results on the entrance surface dose based on optimization considerations involving the cost-effectiveness analysis. Except for chest PA and LAT and skull LAT procedures, all guidance levels derived in this work are less than those recommended by the International Atomic Energy Agency. Survey data and guidance levels were provided to the national authorities to help them develop quality control and radiation protection programs for medical exposures.

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Section: Methodsmentioning

confidence: 99%

Determination of guidance levels of dose for diagnostic radiography in Taiwan

Tung¹,

Tsai²,

Lo³

et al. 2001

Medical Physics

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“…To determine patient doses or doses to the medical staff, Monte Carlo calculations are frequently applied (Zankl et al 2000, Tung et al 1999, Schultz et al 2003. This involves calculating the average or probable behaviour of a system by observing the outcomes of a large number of physical events.…”

Section: Introductionmentioning

confidence: 99%

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

Struelens

Kauwenberghs²,

Vanhavere

2011

Phys. Med. Biol.

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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.

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Skin dose measurements on patients for diagnostic and interventional neuroradiology: a multicentre study

Struelens

Vanhavere²,

Bosmans³

et al. 2005

Radiation Protection Dosimetry

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The present study reports on the skin dose measurements on patients undergoing diagnostic and interventional neuroradiology procedures. Grids of thermoluminescence dosemeters were attached on the head of the patient. The exposure parameters of the X-ray systems and the clinical procedures were fully documented. While for the diagnostic procedure, the dose threshold of 2 Gy for deterministic effects was not reached, this situation was much different for the embolisations. For angiography of the carotid arteries, no skin doses were measured >320 mGy. For the cerebral embolisations, maximum skin doses up to 5.4 Gy were measured. Doses to the patients varied largely between different hospitals and within the same hospital for similar procedures. On the one hand, the complexity of the pathology for interventional procedures was responsible for the large variability in dose. On the other hand, large differences in clinical protocol and technical parameters of the X-ray systems, explaining the dose variations, were also observed. A correlation was found between the maximum skin dose measured on a patient and the total dose-area product (DAP) value for cerebral embolisations. This correlation makes it possible to estimate the maximum skin dose from these DAP values and to determine a trigger level. In conclusion, management of patient doses in interventional radiology requires training, specialisation and well-documented procedure guidelines.

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Determination of Entrance Skin Doses and Organ Doses for Medical X Ray Examinations

Cited by 7 publications

References 0 publications

Determination of guidance levels of dose for diagnostic radiography in Taiwan

Determination of guidance levels of dose for diagnostic radiography in Taiwan

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

Skin dose measurements on patients for diagnostic and interventional neuroradiology: a multicentre study

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