Dependence of scatter on atomic number for x rays from tungsten and molybdenum anodes in the mammographic energy range

Aus, R J; DeWerd, L; Pearson, D.W.; Micka, J; Kh, Ng

doi:10.1118/1.598625

Cited by 2 publications

(4 citation statements)

References 5 publications

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“…[ 30 ] Photoelectric absorption simply expressed in (Z/E) 3 , where E is the energy and Z is the atomic number of the materials. [ 31 32 ] At higher concentration of magnetite, the Z eff values were higher, it was around 18.060. It enables to enhance the photoelectric absorption in lower energies and considerable element composition dependence was observed.…”

Section: Discussionmentioning

confidence: 99%

Evaluation of radiation shielding properties of the polyvinyl alcohol/iron oxide polymer composite

Srinivasan¹,

Samuel

2017

J Med Phys

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Context:Lead is the conventional shielding material against gamma/X-rays. It has some limitations such as toxic, high density, nonflexibility, and also bremsstrahlung production during electron interaction. It may affect the accuracy of radiotherapy outcome.Aims:To theoretically analyze the radiation shielding properties of flexible polyvinyl alcohol/iron oxide polymer composite with five different concentrations of magnetite over the energy range of 15 KeV–20 MeV.Subjects and Methods:Radiological properties were calculated based on the published literature. Attenuation coefficients of pure elements are generated with the help of WinXCOM database.Results:Effective atomic numbers and electron density are increased with the concentration of magnetite. On the other hand, the number of electrons per gram decreased. Mass attenuation coefficient (μ/ϼ) and linear attenuation coefficients (μ) are higher in the lower energy <100 KeV, and their values decreased when the energy increased. Computed tomography numbers (CT) show the significant variation between the concentrations in <60 KeV. Half-value layer and tenth-value layers are directly proportional to the energy and indirectly proportional to the concentration of magnetite. Transmission curve, relaxation length (ƛ), kinetic energy released in the matter, and elemental weight fraction are also calculated and the results are discussed.Conclusions:0.5% of the magnetite gives superior shielding properties compared with other concentrations. It may be due to the presence of 0.3617% of Fe. Elemental weight fraction, atomic number, photon energy, and mass densities are the important parameters to understand the shielding behavior of any material.

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Section: Discussionmentioning

confidence: 99%

Evaluation of radiation shielding properties of the polyvinyl alcohol/iron oxide polymer composite

Srinivasan¹,

Samuel

2017

J Med Phys

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“…Foi simulada a energia absorvida pelo volume de interesse e a estimativa da exposição foi realizada através da aplicação da Equação 7, descrita por Attix (1986), que relaciona a exposição (X) com a energia total absorvida (Eab), que foi simulada, com o Wpar = 33,94 J/C (ATTIX, 1986), representando a energia média gasta pelo gás (no caso ar) para gerar um par elétron-íon positivo.…”

Section: Materiais E Métodosunclassified

Section: Introductionunclassified

“…De acordo com Ng (2000), Wu (1991) e Aus (1999), os valores para XESE devem ser medidos, e uma análise criteriosa dos fatores de erros associados deve ser realizada. Fatores geométricos da câmara de ionização no campo útil de radiação devem ser considerados, pois podem resultar em variação da ordem de 10% dos valores de exposição (Aus, 1999). A exposição na entrada da pele é associada a cada exposição free in air seguindo as recomendações da Associação Americana de Físicos em Medicina (American Association of Physicists in Medicine, AAPM) (AAPM 1985, AAPM 1989, AAPM 1990.…”

Section: Introductionunclassified

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Aplicabilidade da Lei do Inverso do Quadrado da Dis-tância em radiologia convencional e mamografia

Lima¹,

Hoff²

2015

Braz. J. Rad. Sci.

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The Inverse Square Law (ISL) is a mathematical rule used to adjust the KERMA and exposure to different distances of focal spot having as reference a determined point in space. Taking into account the limitations of this rule and its application, we have as main objective to verify the applicability of ISL to determine exposure on radiodiagnostic area (maximum tensions between 30kVp and 150kVp). Experimental data was collected, deterministic calculation and simulation using Monte Carlo Method (Geant4 toolkit) were applied to conventional radiology and mammography. The experimental data was collected using a calibrated ionizing chamber TNT 12000 from Fluke. The conventional X-ray equipment used was a Multix Top of Siemens, with Tungsten track and total filtration equivalent to 2.5 mm of aluminum; and the mammographic equipment was a Mammomat Inspiration from Siemens, presenting the track-add filtration combinations of Molybdenum-Molybdenum, Molybdenum-Rhodium, Tungsten-Rhodium. Both equipments have the Quality Control testes in agreement to Brazilian regulations. Based on the results it is possible conclude that the ISL presents lower performance in correct measurements on mammography spectra, i.e. the associated error (differences) achieves a value up to 77.8% and it can cause significant impact on both areas depending on the spectra energy and distance to correct.

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Dependence of scatter on atomic number for x rays from tungsten and molybdenum anodes in the mammographic energy range

Cited by 2 publications

References 5 publications

Evaluation of radiation shielding properties of the polyvinyl alcohol/iron oxide polymer composite

Evaluation of radiation shielding properties of the polyvinyl alcohol/iron oxide polymer composite

Aplicabilidade da Lei do Inverso do Quadrado da Dis-tância em radiologia convencional e mamografia

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