Percent depth doses and X-ray beam characterizations of a fluoroscopic system incorporating copper filtration

Wunderle, Kevin; Godley, A.; Shen, Zhongzhou; Rakowski, J; Dong, Frank

doi:10.1002/mp.12109

Cited by 6 publications

(7 citation statements)

References 16 publications

(22 reference statements)

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“…Figures (a) and (b) illustrate the x‐ray beam profiles at 60 kVp without filtration and with the maximum available filtration (0.9 mm Cu) in the 42‐cm FOV and the 22‐cm FOV; their respective first half value layers in mm of aluminum are 2.19 and 6.25, as reported in the previous publication . The values reported are normalized to the x‐ray beam central‐axis 10‐mm depth measurement.…”

Section: Resultsmentioning

confidence: 93%

“…As stated previously, the values reported here were normalized to the central‐axis 10‐mm depth measurement. To use these data for dosimetric purposes, one must first reference previously published PDD data for these x‐ray beam spectra . The supplemental material has an example of how to use these data to calculate a dose at some depth in water or water‐equivalent media.…”

Section: Discussionmentioning

confidence: 99%

“…The fluoroscopic x‐ray beam qualities used in this investigation were characterized by the first half‐value layers (HVLs), second HVLs, and homogeneity coefficients. The methodology for measuring x‐ray beam quality and results of these techniques have been reported previously …”

Section: Methodsmentioning

confidence: 99%

“…A previous study characterized the x‐ray beam spectra commonly used by state‐of‐the‐art fluoroscopes during FGI procedures and investigated the percent depth doses (PDDs) from these modern x‐ray beam qualities, allowing for estimation of dose at depth in soft tissue . As is typical, this previous study reported PDDs only along the central axis of the x‐ray beam.…”

Section: Introductionmentioning

confidence: 99%

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Technical Note: Characterization of x‐ray beam profiles for a fluoroscopic system incorporating copper filtration

et al. 2019

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Purpose The goal of this study was to investigate x‐ray beam profiles at various water depths to characterize the two‐dimensional x‐ray dose distribution, allowing for off‐axis and out‐of‐field radiation dose estimation for a wide range of x‐ray beam spectra commonly encountered in fluoroscopically guided interventional procedures. Methods A Siemens Artis interventional fluoroscope was operated in a service mode to generate a continuous x‐ray beam at fixed x‐ray beam spectra, defined by their kVp and the thickness of additional copper filtration. A PTW scanning water tank with a diode detector was used to measure the x‐ray beam profiles at several depths in water at various fields of view and x‐ray beam spectra, both parallel and perpendicular to the anode‐cathode axis direction. Results X‐ray beam profiles, including out‐of‐field tails, were characterized for a wide range of beam qualities. The anode heel effect was pronounced even at depth, resulting in large dose variations across the x‐ray field; this effect was even more definite at large fields of view, at higher kVps, and in the absence of additional copper filtration. Conclusions This study investigated and characterized 2D radiation dose deposition in water from x‐ray beam spectra commonly used by modern fluoroscopes in interventional procedures. This knowledge can be applied to manual dosimetry calculations or can be used to refine the accuracy of automated dose mapping tools or Monte Carlo simulations of the radiation dose to soft tissue within the x‐ray field and to tissue adjacent to the primary beam. Additionally, this study illustrates a substantial reduction of the anode heel effect by using moderate amounts of additional copper filtration to harden the x‐ray beam spectrum.

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Section: Resultsmentioning

confidence: 93%

Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Technical Note: Characterization of x‐ray beam profiles for a fluoroscopic system incorporating copper filtration

et al. 2019

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“…Backscatter factors have been calculated using Monte Carlo simulations for a variety of x‐ray beam qualities, and for filtered x‐ray beams intended to reduce patient dose . More recently, Wunderle et al measured BSFs for a modern fluoroscope that employs copper (Cu) filtration, using polymethyl methacrylate (PMMA) blocks and an over‐table x‐ray tube setup . The authors found that BSF depended on kVp, added Cu filter thickness, and x‐ray field size, and ranged from 1.18 (using 60 kVp, 0.0 mm Cu, 11 cm field of view) to 1.58 (using 80 kVp, 0.9 mm Cu, 42 cm field of view).…”

Section: Introductionmentioning

confidence: 99%

Evaluation of skin dose calculation factors in interventional fluoroscopy

DeLorenzo

Goode

2019

J Applied Clin Med Phys

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PurposeThe purpose of this study was to measure fluoroscopic dose calculation factors for modern fluoroscopy‐guided interventional (FGI) systems, and to fit to analytical functions for peak skin dose (PSD) calculation.MethodsTable transmission factor (TTF), backscatter factor (BSF), and a newly termed kerma correction factor (KCF) were measured for two interventional fluoroscopy systems. For each setup, air kerma rates were measured using a small ionization chamber in fluoroscopic service mode while selecting kVp, copper (Cu) filter thickness, incident angle, and x‐ray field size at the assumed patient skin locations. Angle dependency on KCF was measured on the GE system at isocenter for angles of 0, 15, 30, and 40 degrees, using a range of kVp, Cu filters, and one field size. An analytical equation was created to fit the data to facilitate PSD calculation.ResultsFor the GE system, oblique incidence measurements show KCF decreased by about 2%, 8%, and 13% for incident angles of 15, 30, and 40°, respectively, relative to KCF at 0 degree. The GE and Siemens systems' KCFs ranged from 0.89 to 1.45, and 0.64 to 1.44, respectively. The KCFs increased with a power of field size, and generally increased with kVp and Cu filter. The average percentage difference between TTF × BSF × f and KCF was 16% at normal incidence. The KCF data were successfully fitted to function of angle, field size, kVp, and Cu filter thickness using seven parameters, with an average R‐squared value of 0.98 and maximum percentage difference of 6.0%.ConclusionsThis study evaluated scatter factors for two fluoroscopy systems, and dependencies on angle, kVp, Cu filter, and field size, with emphasis on under table beam orientations. Analytical fitting of the data with exposure parameters may facilitate PSD calculations, and more accurately determine the potential for radiation‐induced skin injury.

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Technical note: Relationship between peak skin dose and fluoroscopic K_a,r: Clinical variations and application in establishing substantial radiation dose levels

Fong

Wunderle

2022

Medical Physics

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Background:The reference point cumulative air kerma (K a,r ) is a commonly used dose quantity for establishing substantial radiation dose levels (SRDLs) that can provide guidance for patient dose management actions following fluoroscopically guided procedures. However, the K a,r may not correlate well with the patient peak skin dose (D skin,max ) because the relationship between K a,r and D skin,max may vary widely due to clinical variations. Therefore, it may be prudent for institutions to establish different K a,r -based SRDL values based on the clinical procedure type. Purpose: The present study investigates the relationship between K a,r and D skin,max for different clinical services and how that variation may overestimate or underestimate the need for patient follow-up. Additionally, the study suggests a possible framework for establishing K a,r SRDLs based on the clinical data analysis. Methods: A retrospective analysis was performed for fluoroscopically guided interventions exceeding 5 Gy K a,r . For each procedure, the patient D skin,max was estimated and the ratio of D skin,max to K a,r (DKR) was calculated. Results were pooled into one of three clinical service categories: body interventions (n = 33), cardiac interventions (n = 81), or neurological (neuro) interventions (n = 44). The distributions in K a,r , D skin,max , and DKR were analyzed in aggregate and by the clinical service category. Results: The median K a,r values for procedures exceeding 5 Gy were 6.0 Gy (95% CI [5.6, 6.4]) for body interventions, 5.8 Gy (95% CI [5.5, 6.0]) for cardiac interventions, and 6.3 Gy (95% CI [5.9, 6.6]) for neuro interventions. D skin,max for the same procedure data sets were 5.0 Gy (95% CI [4.4, 5.6]) for body interventions, 5.5 Gy (95% CI [5.2, 5.8]) for cardiac interventions, and 3.7 Gy (95% CI [3.4, 4.0]) for neuro interventions. This resulted in median DKR values of 0.81 for body interventions, 0.91 for cardiac interventions, and 0.59 for neuro interventions.Conclusions: This study illustrates the need to understand the relationship between the reported K a,r and the patient D skin,max for different types of interventional procedures. This is especially important when an institution uses K a,r as the parameter for establishing an SRDL threshold to identify patients who may require clinical follow-up. The implications of this research and a guide for how to implement these findings are elaborated on in the Discussion.

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Percent depth doses and X-ray beam characterizations of a fluoroscopic system incorporating copper filtration

Abstract: The data sets of X-ray beam characteristics and PDDs presented in this study can be used to estimate organ or soft tissue doses at depth involving similar beam qualities or to compare with mathematical models.

Cited by 6 publications

References 16 publications

Technical Note: Characterization of x‐ray beam profiles for a fluoroscopic system incorporating copper filtration

Technical Note: Characterization of x‐ray beam profiles for a fluoroscopic system incorporating copper filtration

Evaluation of skin dose calculation factors in interventional fluoroscopy

Technical note: Relationship between peak skin dose and fluoroscopic K_a,r: Clinical variations and application in establishing substantial radiation dose levels

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Percent depth doses and X-ray beam characterizations of a fluoroscopic system incorporating copper filtration

Abstract: The data sets of X-ray beam characteristics and PDDs presented in this study can be used to estimate organ or soft tissue doses at depth involving similar beam qualities or to compare with mathematical models.

Cited by 6 publications

References 16 publications

Technical Note: Characterization of x‐ray beam profiles for a fluoroscopic system incorporating copper filtration

Technical Note: Characterization of x‐ray beam profiles for a fluoroscopic system incorporating copper filtration

Evaluation of skin dose calculation factors in interventional fluoroscopy

Technical note: Relationship between peak skin dose and fluoroscopic Ka,r: Clinical variations and application in establishing substantial radiation dose levels

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Technical note: Relationship between peak skin dose and fluoroscopic K_a,r: Clinical variations and application in establishing substantial radiation dose levels