Assessment of organ and effective dose when using region-of-interest attenuators in cone-beam CT and interventional fluoroscopy

Xiong, Zhenyu; Vijayan, Sarath; Rudin, Stephen; Bednarek, Daniel R.

doi:10.1117/1.jmi.4.3.031210

Cited by 9 publications

(7 citation statements)

References 31 publications

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“…9, 10 The ROI attenuator was inserted at the center of the x-ray field, and the phantom was irradiated with the x-rays using the identical setup as described in section 2.3.1. The resultant dose distribution was comprised of a high dose circular region of interest and a low dose periphery due to the dose intensity attenuation by the ROI beam attenuator.…”

Section: Methodsmentioning

confidence: 99%

Calculation of forward scatter dose distribution at the skin entrance from the patient table for fluoroscopically guided interventions using a pencil beam convolution kernel

Vijayan¹,

Xiong²,

Guo³

et al. 2018

Medical Imaging 2018: Physics of Medical Imaging

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The forward-scatter dose distribution generated by the patient table during fluoroscopic interventions and its contribution to the skin dose is studied. The forward-scatter dose distribution to skin generated by a water table-equivalent phantom and the patient table are calculated using EGSnrc Monte-Carlo and Gafchromic film as a function of x-ray field size and beam penetrability. Forward scatter point spread function’s (PSFn) were generated with EGSnrc from a 1×1 mm simulated primary pencil beam incident on the water model and patient table. The forward-scatter point spread function normalized to the primary is convolved over the primary-dose distribution to generate scatter-dose distributions. The utility of PSFn to calculate the entrance skin dose distribution using DTS (dose tracking system) software is investigated. The forward-scatter distribution calculations were performed for 2.32 mm, 3.10 mm, 3.84 mm and 4.24 mm Al HVL x-ray beams for 5×5 cm, 9×9 cm, 13.5×13.5 cm sized x-ray fields for water and 3.1 mm Al HVL x-ray beam for 16.5×16.5 cm field for the patient table. The skin dose is determined with DTS by convolution of the scatter dose PSFn’s and with Gafchromic film under PMMA “patient-simulating” blocks for uniform and for shaped x-ray fields. The normalized forward-scatter distribution determined using the convolution method for water table-equivalent phantom agreed with that calculated for the full field using EGSnrc within ±6%. The normalized forward-scatter dose distribution calculated for the patient table for a 16.5×16.5 cm FOV, agreed with that determined using film within ±2.4%. For the homogenous PMMA phantom, the skin dose using DTS was calculated within ±2 % of that measured with the film for both uniform and non-uniform x-ray fields. The convolution method provides improved accuracy over using a single forward-scatter value over the entire field and is a faster alternative to performing full-field Monte-Carlo calculations.

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Section: Methodsmentioning

confidence: 99%

Calculation of forward scatter dose distribution at the skin entrance from the patient table for fluoroscopically guided interventions using a pencil beam convolution kernel

Vijayan¹,

Xiong²,

Guo³

et al. 2018

Medical Imaging 2018: Physics of Medical Imaging

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“…All parts of the tube were simulated according to the manufacturer’s specifications. 3 We used the XTUBE component module (CM) of the BEAMnrc code library to simulate the tube target, with a target material of tungsten–rhenium (WRe) and an anode angle of 11 deg. The incident electron energy was simulated using a constant potential with no ripple.…”

Section: Methodsmentioning

confidence: 99%

“…The anode bremsstrahlung cross-section enhancement was increased by a factor equal to 200. 3 In all simulations, the photon energy cut-off (global PCUT) was set to 10 keV for range rejection. 4 Material data were generated by the PEGS4 code developed at the National Research Council.…”

Section: Methodsmentioning

confidence: 99%

Investigation of organ dose variation with adult head size and pediatric age for neuro-interventional projections

Xiong

Vijayan

Guo

et al. 2018

Medical Imaging 2018: Physics of Medical Imaging

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The purpose of this study was to evaluate the effect of patient head size on radiation dose to radiosensitive organs, such as the eye lens, brain and spinal cord in fluoroscopically guided neuro-interventional procedures and CBCT scans of the head. The Toshiba Infinix C-Arm System was modeled in BEAMnrc/EGSnrc Monte-Carlo code and patient organ and effective doses were calculated in DOSxynrc/EGSnrc for CBCT and interventional procedures. X-ray projections from different angles, CBCT scans, and neuro-interventional procedures were simulated on a computational head phantom for the range of head sizes in the adult population and for different pediatric ages. The difference of left-eye lens dose between the mean head size and the mean ± 1 standard deviation (SD) ranges from 20% to 300% for projection angles of 0° to 90° RAO. The differences for other organs do not vary as much and is only about 10% for the brain. For a LCI-High CBCT protocol, the difference between mean and mean ± 1 SD head size is about 100% for lens dose and only 10% for mean and peak brain dose; the difference between 20 and 3 year-old mean head size is an increase of about 200% for the eye lens dose and only 30% for mean and peak brain dose. Dose for all organs increases with decreasing head size for the same reference point air kerma. These results will allow size-specific dose estimates to be made using software such as our dose tracking system (DTS).

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“…As a result, flat‐panel detectors have been developed and used as alternatives due to their significantly higher contrast and spatial resolution 62,63 . As for the radiation dose, Xiong et al 64 demonstrated the efficacy of region of interest (ROI) imaging using an ROI attenuator composed of 0.7‐mm‐thick Cu in reducing the patient radiation dose in CBCT. Compared to standard neuro‐CBCT scans without the ROI attenuator, the dose for most organs was reduced by 45%–50%, with an effective dose of approximately 46%.…”

Section: Cbct Perfusion Techniquementioning

confidence: 99%

Advances in cerebral perfusion imaging techniques in acute ischemic stroke

Fang

Cheng

et al. 2022

J of Clinical Ultrasound

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The application of cerebral perfusion imaging has demonstrated significant assessment benefits and an ability to establish an appropriate triage of patients with acute ischemic stroke (AIS) and large artery occlusion (LAO) in the extended time window. Computed tomography perfusion (CTP) and magnetic resonance imaging (MRI) are routinely used to determine the ischemic core, as well as the tissue at risk, to aid in therapeutic decision‐making. However, the time required to transport patients to imaging extends the door‐to‐reperfusion time. C‐arm cone‐beam CT (CBCT) is a novel tomography technology that combines 2D radiography and 3D CT imaging based on the digital subtraction angiography platform. In comparison with CT or MRI perfusion techniques, CBCT combined with catheterized angiogram or therapy can serve as a “one‐stop‐shop” for the diagnosis and treatment of AIS, and greatly reduce the door to reperfusion time. Here, we review the current evidence on the efficacy and theoretical basis of CBCT, as well as other perfusion techniques, with the purpose to assist clinicians to establish an effective and repaid workflow for patients with AIS and LAO in clinical practice.

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Assessment of organ and effective dose when using region-of-interest attenuators in cone-beam CT and interventional fluoroscopy

Cited by 9 publications

References 31 publications

Calculation of forward scatter dose distribution at the skin entrance from the patient table for fluoroscopically guided interventions using a pencil beam convolution kernel

Calculation of forward scatter dose distribution at the skin entrance from the patient table for fluoroscopically guided interventions using a pencil beam convolution kernel

Investigation of organ dose variation with adult head size and pediatric age for neuro-interventional projections

Advances in cerebral perfusion imaging techniques in acute ischemic stroke

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