Radiation Absorption
Radiation Absorption - Related Videos
01:05
Absorption of Radiation
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2023
The rate of heat transfer by emitted radiation is described by the Stefan-Boltzmann law of radiation: where σ is the Stefan-Boltzmann constant, a combination of fundamental constants of nature; A is the surface area of the object; and T is its temperature in kelvins. The proportionality to the fourth power of the absolute temperature gives a remarkably strong temperature dependence. It allows the detection of even small temperature variations. Images called thermographs can be used medically...
01:13
Atomic Absorption Spectroscopy: Radiation and Light Sources
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2024
Atomic absorption spectroscopy (AAS) relies on the Beer-Lambert law, which requires that the radiation source emits a narrow range of wavelengths to match the absorption characteristics of the analyte atom. The primary criteria for choosing an appropriate radiation source in AAS is to provide a precise and intense emission at specific wavelengths that will allow accurate detection of the analyte. Two common narrow-range 'line' sources used in AAS are hollow-cathode lamps (HCLs) and...
08:17
Dynamic Lung Tumor Tracking for Stereotactic Ablative Body Radiation Therapy
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Cited by 9 •
2015
Stereotactic ablative body radiation therapy (SBRT) involves the precise delivery of high-dose radiation to cancer tumor targets. A novel SBRT platform offers a first-of-its-kind gimbaled radiation accelerator mounted within a pivoting O-ring gantry capable of dynamic image-guided tumor tracking. Here, we describe dynamic tumor tracking for lung targets.
02:59
Biological Effects of Radiation
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2020
All radioactive nuclides emit high-energy particles or electromagnetic waves. When this radiation encounters living cells, it can cause heating, break chemical bonds, or ionize molecules. The most serious biological damage results when these radioactive emissions fragment or ionize molecules. For example, α and β particles emitted from nuclear decay reactions possess much higher energies than ordinary chemical bond energies. When these particles strike and penetrate matter, they produce ions...
01:19
Drug Absorption: Factors Affecting GI Absorption
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2023
The process of oral drug absorption can be influenced by several factors. Weakly acidic drugs tend to be absorbed more readily from the stomach due to their nonionized state. However, absorption may be less efficient in the upper intestine, where drugs are often ionized. Interestingly, despite the stomach's apparent advantage for drug absorption, its mucous layer can hinder diffusion. Its surface area is also smaller than the intestine's, which can further slow down the absorption rate. In...
FAQs
Allowed energy levels act as the selection condition for absorption. Radiation transfers energy efficiently when its energy matches an available transition in the interacting particles. Depending on the material and radiation, that transition may produce electronic excitation, molecular vibration, molecular rotation, or ionization. This energy-matching principle explains why changing wavelength changes the observed absorption.
Material composition determines which particles can interact with incoming radiation and which energy-transfer channels are available. Wavelength identifies the radiation energy, while thickness affects how much material the radiation encounters. Intensity also changes the amount of incident energy available for transfer. Considering these variables together helps interpret measured absorption rather than attributing every change to material composition.
The transferred energy becomes internal energy, but its immediate form depends on the interaction. It may raise particles to electronically excited states, drive molecular vibrations or rotations, or remove electrons through ionization. These microscopic changes can alter the material’s state, making absorption relevant not only to radiation transport but also to the material response after energy deposition.
Measurements quantify how much radiation a material takes up under specified wavelength, thickness, and intensity conditions. Comparing those results helps characterize the material and reveals how radiation propagates through it. In physics, measured absorption also provides a way to quantify energy deposition, linking an observable radiation change to energy transferred into matter.
A thicker sample presents more material through which radiation can interact, so thickness can influence the measured amount absorbed. Without recording it, comparisons between samples may mix differences in sample geometry with differences in composition or wavelength response. Controlling or reporting thickness therefore improves interpretation of radiation propagation and energy-deposition measurements.
The principle supports spectroscopy, where absorption helps characterize materials; atmospheric and astrophysical observations, where it informs how radiation propagates; and medical imaging and radiation treatment, where energy transfer in matter matters. It also guides optical, thermal, and radiation-shielding system design. These applications use absorption measurements or behavior to connect radiation with material response.