f-number formula

The lower the f‑number the larger the aperture diameter, meaning more thermal IR energy is reaching the infrared sensor. This increases the detail, contrast, and overall performance of the thermal infrared cameras, especially for surveillance where long-range detection, recognition and identification is desired in even in low contrast scenes. A thermal camera’s sensitivity is measured by its NETD (Noise Equivalent Temperature Difference). Often described in millikelvins (mK, thousandths of a degree), NETD is determined by the thermal camera’s sensor sensitivity and the f‑stop of the lens.

MR OEMS rely on the MRID³ᴰ for the commissioning and continuous QA of MRgRT systems. The system is vendor-agnostic and can quantify distortion on systems ranging from 0.35T – 3T.

Lanchun Lu,Xiangyu Yang,Brian Raterman,Xia Jiang,Matthew Meineke,John Grecula,Dukagjin Blakaj,Joshua Palmer,Raju Raval,Evan Thomas,David Hintenlang,Nilendu Gupta (2022), Assessment of MRI image distortion based on 6 consecutive years of annual QAs and measurements on 14 MRI scanners used for radiation therapy, Journal of Applied Clinical Medical Physics, e13843, https://doi.org/10.1002/acm2.13843

Lens fcanon

f-number calculator

MRID³ᴰ uses a proven scientific method to quantify MR Geometric Distortion by adaptation of algorithms used in B0 shimming and gradient coil design. This innovative method allows for a highly accurate, hollow and lighter geometric distortion phantom. Combined with the phantom’s physical features, the MRID³ᴰ provides true submillimeter accuracy.

The large FOV (37 cm x 32 cm) hollow boundary phantom design allows for efficient workflow with setup, scan, and analysis in under 10 minutes. MRID3D includes image analysis software with a built-in 3D DICOM Viewer and Region of Interest (ROI) selector, permitting user analysis of smaller custom volumes.

F-stop chart

QUASAR MRID³ᴰ advanced software provides users with the ability to monitor the performance of their MR system over time. By acquiring routine scans of the phantom on a consistent basis, users can detect changes in their MR system’s magnetic field which may contribute to system troubleshooting and preventative maintenance.

F-number oflens

Unlike our competitors’ solutions, the MRID³ᴰ includes unlimited analyzed scans on one scanner with no expiry. This enables users to test freely without the concern of depleting a defined quota of eligible scans. An optional unlimited system scan license enables multi-system scanning over multiple sites with no expiry.

Locally secure, client-based software designed for fast data transfer by using a built-in DICOM receiver. Advanced algorithms analyze 11,253 data points to report a high-resolution DVF. Results are typically available in under 10 minutes, including setup and scanning. Maintain control of your critical information without a need for cloud-based data management.

QUASAR MRID³ᴰ provides the ability to report spherical harmonic coefficients and automatically quantify B0 and Gradient Non-Linearity distortions. Distortion characterization enables optimization of scan sequences for Radiation Therapy and increased inspection of the DVF. This feature is valuable in advanced imaging techniques such as Diffusion Weighted Imaging (DWI), which is greatly affected by GNL.

Accuracy is further improved by the incorporation of an XYZ detection feature, along with six contrastive fiducials at isocenter. MRID³ᴰ determines any discrepancy with DICOM coordinates and corrects the DVF to remove the effects of laser/couch misalignment or human error. This design promotes accurate data registration, even at high distortion levels.

Lens fvs aperture

Interactive 3D DVF Viewer with ROI selector enables users to update displayed data in real-time to gain additional insights. Multiple visualization tools provide a variety of ways to easily interpret the analysis results. View and report data in statistical and graphical formats using a customizable, simple to use report generator.

Lens fcamera

QUASAR™ MRID3D is a lighter, larger and more efficient way to quantify MRI geometric distortion in 3D. This industry-leading distortion analysis system provides sub-millimeter accuracy and is trusted globally by medical physicists for third party MR-SIM and MR-LINAC commissioning and quality assurance.

f-stop photography

An f‑number (ƒ/#) or f‑stop refers to the ratio of a lens’s focal length to its aperture’s diameter (lens opening vs focal length) and indicates the amount of IR energy (heat) coming through the lens to the infrared sensor. An f/1.0 lens means the aperture diameter is equal to the focal length, whereas an f/2.0 lens would mean the aperture diameter is half of the focal length. Lenses are typically specified with their maximum aperture (some lens apertures are internally adjustable) and max focal length/zoom power.

The QUASAR™ MRID³ᴰ software application is designed with specific needs of MR medical physicists and clinical workflow in mind. Accuracy, speed, and efficiency of results were primary considerations during the design process. The software application is optimized to run locally without load or latency issues, which results in less time waiting for cloud-based applications to generate 3D distortion vector fields. An unlimited scan license for one system is provided with QUASAR™ MRID³ᴰ. This allows users to test freely without the concern of depleting a defined quota of eligible scans. Additional system licenses are available upon request.

The MRID³ᴰ system is designed to maintain geometric integrity, resulting in accurate and reliable distortion analysis over the lifetime of the phantom. The combination of precisely machined fiducials, susceptibility-matched materials and structure volume stabilization features result in a superior geometric distortion solution.

An ƒ/1.0 Ge lens allows for 250% more infrared thermal energy to be transferred to the infrared sensor than an ƒ/1.6 lens. This means the f‑number can be even more important than the sensor as it relates to a camera’s overall NETD sensitivity, particularly for uncooled LWIR cameras which are the most common type of thermal imaging. See the following image for a visual example of how much the area of the aperture changes with different f‑stop values.

The MRID³ᴰ design enables quick setup, scanning and analysis of geometric distortion in as little as 10 minutes. The phantom is pre-filled with high T1W mineral oil and is self-contained with a controlled internal environment, which does not require maintenance over time. In addition, auto-detection and auto-registration processes support quick and accurate data analysis.