Oxford University Press is a department of the University of Oxford. It furthers the University's objective of excellence in research, scholarship, and education by publishing worldwide

x-ray collimator material

Many societies offer single sign-on between the society website and Oxford Academic. If you see ‘Sign in through society site’ in the sign in pane within a journal:

X RayCollimator Price

Simply put, the imaging scanning principle uses transmitted light to generate a signal: a linear scale and a scanning grating of the same or similar pitch move relative to each other. The base of the scanning grating is transparent, while the linear scale, which serves as the measuring reference, can be either transparent or reflective. When parallel light passes through a grating, a light/dark area is formed at a certain distance, and the scanning mask is located at this position. When two gratings are moved relative to each other, the light passing through the linear scale is modulated. If the slits are aligned, the light passes through. If the scribe lines of one grating are aligned with the slits of the other, the light does not pass through. A set of regularly arranged photocells converts these changes in light intensity into electrical signals. A special form of scanning grating modulates the light intensity into a nearly sinusoidal output signal.

X raycollimator ppt

Access to content on Oxford Academic is often provided through institutional subscriptions and purchases. If you are a member of an institution with an active account, you may be able to access content in one of the following ways:

For librarians and administrators, your personal account also provides access to institutional account management. Here you will find options to view and activate subscriptions, manage institutional settings and access options, access usage statistics, and more.

Oxford Academic is home to a wide variety of products. The institutional subscription may not cover the content that you are trying to access. If you believe you should have access to that content, please contact your librarian.

First, the system activates a light source that emits light. The light passes through the grating lines of the linear scale head, creating light and dark interference fringes. One end of the linear scale head is connected to the object to be measured, ensuring that the linear scale head follows the movement of the object. When the object to be measured moves, the linear scale head also moves, causing the relative positions of the interference fringes to change.

X raycollimator diagram

The working principle of linear scale is based on the interference phenomenon of light. The linear scale head contains a series of grating lines that are very evenly spaced. When light passes through these lines, an interference phenomenon occurs, forming light and dark stripes. The spacing of these fringes is closely related to the spacing of the encoder lines. During measurement, one end of the linear scale head is connected to the object to be measured, while the other end is connected to the reading instrument. When the object to be measured moves, the linear scale head also moves, resulting in a change in the relative position of the encoder lines. By measuring the changes in the light and dark stripes on the linear scale head, the displacement of the object to be measured can be determined.

If your institution is not listed or you cannot sign in to your institution’s website, please contact your librarian or administrator.

types of x-ray collimator

The photodetectors in the readout instrument sense the change in the interference fringes and convert it into an electrical signal. The electrical signal undergoes complex signal processing to extract information related to the displacement of the object. After mathematical operations, the final displacement value of the measured object is obtained. The final displacement value is usually shown on a display for the user to observe and record.

Duminda Satharasinghe, J Jeyasugiththan, M Jeyasuthan, T Amalaraj, A L Abeyweera, W M N M B Wanninayake, A S Pallewatte, IMPACT OF COLLIMATION ON RADIATION EXPOSURE IN ADULT AND PAEDIATRIC DIGITAL X-RAY IMAGING, Radiation Protection Dosimetry, Volume 197, Issue 1, November 2021, Pages 19–27, https://doi.org/10.1093/rpd/ncab155

Linear scale is a kind of sensor widely used in measurement and positioning systems, which realizes high precision measurement by detecting the phase change of light. This linear scale usually consists of a light source, a grating, a detector, and a signal processing unit, and has the advantages of high precision and fast response speed. The following is a detailed article from the sisco store about the working principle of linear scale.

As a high-precision measurement and positioning sensor, high quality linear scale realizes accurate measurement of position by using the fluctuation of light and the principle of interference. Its structure is simple, stable work, and is widely used in machinery manufacturing, semiconductor production, and other fields. With the continuous progress of science and technology, linear scale will continue to play an important role in the field of precision measurement, promoting the development of industrial automation and intelligent manufacturing.

What iscollimationin radiology

This study aimed to evaluate the collimation practices and quantify the overexposure due to extensive X-ray field area. The study was carried out in four digital X-ray units (including one paediatric X-ray unit). A total of 749 X-ray projections (555 adult and 194 paediatric) were evaluated. In adult X-ray units, the radiation field size was two times larger than the electronically collimated field. In the paediatric unit, the radiation field was 3.7 times larger than the electronic collimated field. The average additional entrance surface dose due to the excess radiation field used in a paediatric X-ray unit varied between 9.3 (2.5%) and 201.4 |$\mu $|Gy (10.9%). Therefore, proper pre-patient collimation should be applied whenever feasible, which reduces the patient radiation dose considerably.

Choose this option to get remote access when outside your institution. Shibboleth/Open Athens technology is used to provide single sign-on between your institution’s website and Oxford Academic.

Typically, access is provided across an institutional network to a range of IP addresses. This authentication occurs automatically, and it is not possible to sign out of an IP authenticated account.

use of collimator in x-ray

The interference scanning principle utilizes the diffraction and interference of fine gratings to create signals for position measurement movements. Linear scales with stepped light are inscribed on a flat reflective surface with a 0.2 um high reflective line. The linear scale in front of the scanning grating, its grating distance, and linear scale grating distance are the same, it is the transmission phase grating.

The relative motion of the scanning grating and the linear scale causes the diffracted light of the first stage to be phase-shifted: when the grating is moved over a pitch, the +1 diffracted light of the previous stage is shifted in the positive direction by one light wavelength, and the -1 diffracted light is shifted in the negative direction by one light wavelength. Since these two light waves will interfere when they leave the scanning grating, the light waves will be shifted by two wavelengths relative to each other. That is to say, relative movement of a grating distance can be obtained in two signal periods.

When the light shines on the scanning grating, the light is diffracted into three beams of light intensity approximation: -1, 0, and +1. In the light wave diffracted by the linear scale, the strongest beams of diffracted light intensity of the reflected light are +1 and -1. These two beams of light in the scanning grating meet again at the phase light shed, and once again be diffracted and interfered with. It forms three beams of light that leave the scanning grating at different angles. The photocell converts these alternating light intensity changes into electrical signals.

Shop on sisco.com for all of your industrial test and measurement equipment & accessories including portable detectors, meters, testers, scales, etc.