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Technical Note: Sheet-based dynamic beam attenuator - A novel concept for dynamic fluence field modulation in x-ray
Sascha Manuel Huck1,2, George S K Fung3,4, Katia Parodi2
1Siemens Healthcare GmbH, Siemensstr. 3, 91301, Forchheim, Germany.
Medical Physics
|July 27, 2019
Summary
A novel sheet-based dynamic beam attenuator (sbDBA) allows computed tomography (CT) to adjust x-ray intensity in real-time. This innovation homogenizes image noise and optimizes radiation dose delivery, improving CT imaging capabilities.
Area of Science:
- Medical Imaging
- Radiological Physics
Background:
- Computed tomography (CT) aims to compensate for patient attenuation during data acquisition.
- Current bowtie filters cannot adapt x-ray intensity profiles dynamically.
- Patient attenuation varies spatially and temporally, impacting image quality and dose distribution.
Purpose of the Study:
- To introduce a novel sheet-based dynamic beam attenuator (sbDBA) concept.
- To enable dynamic shaping of the x-ray transmission profile in CT.
- To homogenize image noise and optimize radiation dose delivery.
Main Methods:
- The sbDBA utilizes an array of metal sheets focused toward the focal spot.
- Intensity modulation is achieved by controlled defocusing of the sheet array.
- The concept was evaluated using Monte Carlo simulations and experimental measurements on a clinical CT scanner.
Main Results:
- Experimental measurements confirmed the sbDBA's ability to dynamically alter the attenuation profile's width and location.
- The sbDBA demonstrated consistent transmission properties across various tube voltages.
- Monte Carlo simulations indicated minimal impact on the energy spectrum and negligible scatter emission toward the patient.
Conclusions:
- The sbDBA concept for dynamic beam attenuation was successfully demonstrated.
- The sbDBA offers advantages over conventional bowtie filters, including no filter-induced beam hardening or scatter.
- This technology supports region of interest (ROI) imaging and further patient dose reduction.
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