Rigaku CT Scanner FAQs

Industrial CT uses microfocus X-ray sources plus high-precision stages to achieve higher resolution with voxel sizes 10–1,000 times finer than medical CT (e.g., down to sub-micron with nano3DX). The X-ray voltage tends to be higher for industrial CT to handle heavily absorbing materials, such as metals and ceramics. Both use X-ray attenuation, and the image reconstruction methods are similar, but industrial systems are optimized for higher spatial resolution and a wider variety of sample materials and sizes. (Blog: Industrial vs. Medical CT Scanners: What Are the Differences?)

Filtered back-projection (FBP) is the most commonly used reconstruction algorithm. All Rigaku systems include reconstruction software and a workstation with high-spec GPUs to run reconstructions fast. (Blog: How Does CT Reconstruction Work?)

The achievable spatial resolution largely depends on the sample size and the scanner’s specifications. The resolution of most CT scanners ranges from a few microns to hundreds of microns. When the sample size and scan conditions are optimized, Rigaku CT scanners can achieve the following spatial resolutions:

• nano3DX: 0.7–1 µm at ϕ0.66 mm FOV
• CT Lab HX: 4.2 µm at ϕ5 mm FOV
• CT Lab GX: 15 µm at ϕ36 mm FOV
• CT Lab HV: 3 µm at ϕ4 mm FOV

(Compare the specifications of all Rigaku X-ray CT products)

It depends. CT Lab HV’s 225 kV X-ray source generates high-energy X-rays, which can penetrate through dense materials like steel up to a couple of tens of millimeters or tungsten up to a few millimeters in thickness.

No. The CT Lab GX keeps the sample stationary and instead rotates the source-detector gantry, which can be especially beneficial for some in-situ measurements involving liquids or fragile samples.

First, you need to know your sample's general composition, density, and thickness. Then, consult published experimental results or X-ray absorbance characteristics to establish a starting point for kV and filter material. Finally, perform short test scans and evaluate them based on specific image quality metrics, such as the signal-to-noise (SNR) or contrast-to-noise (CNR) ratio for materials phases, the ease of segmentation of material phases, or the presence and severity of artifacts. Visual inspection of images alone can be misleading, so quantitative tools are better to gauge image quality. Generally, higher density or thicker samples (like metals or large rocks) require higher kV and more absorbing filters (e.g., Cu, Sn) to minimize beam hardening, while light, low-density, or thin samples (like polymers or biological materials) benefit from lower kV and lighter filters (e.g., Al, or no filter) to achieve good contrast. (Blog: How to Choose kV and Filter for Your Micro-CT Experiment)

Begin by defining the smallest feature size (L) you need to observe, and then set the voxel size accordingly: L/5 to L/2 if simply identifying the feature is sufficient, or L/20 to L/5 for quantitative analysis of its shape and size. The voxel size is determined by the detector pixel size divided by the magnification factor, meaning increasing magnification is a key method to decrease voxel size and improve resolution. Also, minimize the X-ray focus size if it is adjustable. Additionally, optimize the X-ray energy by selecting the appropriate X-ray tube voltage (kV) and filter based on your sample's density and size to achieve good contrast and minimize artifacts, such as beam hardening. If these adjustments to enhance resolution lead to a lower signal-to-noise ratio (SNR), compensate by increasing the number of projections or the scan time. (Blog: How to Improve the Resolution of X-ray CT Images)

TIFF is the most universal industrial CT image file format supported by most analysis software. Additionally, DICOm and RAW are occasionally used. Some software packages can also generate VGStudio-MAX compatible *.vgl and surface meshes (STL, OBJ) for CAD overlay or finite-element simulation.

Rigaku CT scanners use traditional micro X-ray sources with no water cooling, and they generally do not require daily maintenance. Running automatic alignment and detector calibration are recommended when the scan settings are changed. (Please contact the service team if you have any questions about your Rigaku CT scanner maintenance.)

All CT Lab systems come with lifetime application support. Whether you need help to optimize scan parameters or need data analysis assistance, Rigaku application scientists can help you with your CT questions beyond initial training.