Magnification occurs in x-ray imaging because the x-rays are divergent or spread out from the x-ray source. Therefore, the object will appear larger on the detector than the true object size. Magnification in radiography is defined as (Image Size/Object Size) and is equal to the (SID/SOD) which is the source to image distance divided by […]
Beam Quality describes the shape of the energy spectrum (i.e. the energy distribution of the x-rays) and beam quantity describes the total intensity of the spectrum (i.e. the area under the x-ray spectrum curve). In this post we describe the factors affecting beam quality including: kVp, target material, and pre-patient collimation. We also discuss the
Beam Quality, Beam Quantity (mA, kVp, HVL) for Radiologic Technologist Read More »
The motivation for gonad shielding is to reduce the hereditary specific risks of radiation, and it is still common practice at many institutions. The reasons that shielding will soon be phased out include: hereditary risk in humans has not been demonstrated even at high doses, the radiation doses have reduced greatly from the 1950s (orders
The body is composed of individual cells wherein the genetic information is stored in DNA (deoxyribose nucleic acid). This DNA can be damaged by ionizing radiation, i.e. radiation which has sufficient energy to remove electrons from atoms. The DNA damage can be either direct (i.e. the electron hits the DNA directly) or indirect (i.e. the
The radiation dose for x-ray radiography and CT is compared with the background radiation dose levels (average in United States of 3mSv). The different exams Abdomen, Bone, Head and Neck, Chest, Cardiac, and Mammography are presented. For reference the sources of background radiation of cosmic radiation and Radon are presented. Background Radiation Overview To provide
The x-ray interactions are Photoelectric, Compton and Coherent. Photoelectric is mainly responsible for image contrast, Compton contributes to artifacts in the images, and Coherent scattering has little influence in most diagnostic (x-ray/CT) procedures. Overview of the Physics Behind X-Ray Interactions When x-rays interact with the human body during an x-ray exposure, they form an image
Basics of x-ray properties for radiographers and radiologic technologists include: wave and particle models for x-rays, relationships between Energy, wavelength and frequency, and 1/R^2 effect. Radiation Radiation is energy emitted/transmitted as a wave or particle that travels through a medium (such as the air or a patient). A brief comparison of the different types of
X-Ray Properties (Energy, Wavelength, Inverse Square Law) For Radiologic Technologists Read More »
X-ray scatter due to Compton Scatter generates background haze in x-ray images and there is a desire to reduce the scatter impact on image quality. X-ray scatter depends on several physical factors including: body habitus (increases with increased habitus), kVp, collimation (increases with increased kVp), air gap (decreases with increased air gap), and anti-scatter grids
The basic concepts of digital x-ray detectors are covered including the important concepts. Digital detectors are separated into small individual components termed detector elements (DELs), and the size of individual DELs is referred to as the pixel pitch. Whereas the matrix size is the number of DELs in each direction on the detector. The signal
Digital X-ray Imaging [Dels, Matrix Size, Bit Depth , Dynamic Range, Sampling Frequency] Read More »
Introduction As a radiologic technologist one of your primary responsibilities is to get X-rays images with satisfactory image quality at a radiation dose that is As Low as Reasonably Achievable (ALARA). With this in mind, you must have a good understanding of the basis concepts in radiation dose measurements and the units for measuring radiation
What Radiologic Technologists must know about Radiation Dose Units (mGy, mSv). Read More »
