Determination of Half-Value Layer

Ed, Trout; Jp, Kelley; Ac, Lucas

doi:10.1148/73.1.107b

Cited by 20 publications

(34 citation statements)

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“…1). A 5 cm clinical cone was mounted on the Pantak [4] and in accordance with the procedure of Trout et al [2] high purity aluminium absorbers were placed such that the FCD = 2 9 FAD for FCD values of 30, 60, 90 and 130. The latter value corresponds to the FCD used at ARPANSA in the determination of air kerma calibration coefficients for secondary standard chambers as a function of beam quality (0.35 mm Al-3.98 mm Cu) and an FCD = 30 cm is consistent with the configuration used at our facility to establish reference HVL values for clinically used X-ray beams, namely those associated with the manufacturer supplied filter inserts 4-8.…”

Section: Hvl Determinationmentioning

confidence: 99%

“…Following the IPEMB code of practice for the determination of absorbed dose to water [1] such beam qualities constitute both low (1-8 mm Al) and medium (0.5-4 mm Cu) energy X-rays and the protocol requires beam specific measurements of HVL as a pre-requisite in order to determine parameters such as backscatter factors and mass-energy absorption coefficient water to air ratios. There are guidelines on optimal measurement geometry for a determination of HVL for orthovoltage X-rays based on the work of Trout et al [2] which may be adopted for superficial X-rays, such as those generated by the Pantak system. Such guidelines include collimation to achieve a narrow beam cross-section and a focal spot to chamber distance (FCD) that is double the focal spot to absorber distance (FAD) and FCD preferably 80-100 cm.…”

Section: Introductionmentioning

confidence: 99%

“…Such guidelines include collimation to achieve a narrow beam cross-section and a focal spot to chamber distance (FCD) that is double the focal spot to absorber distance (FAD) and FCD preferably 80-100 cm. Since for orthovoltage beams it has been shown that factors such as FCD and aperture size influence measured HVL values [2,3] the term apparent HVL is appropriate for empirically determined values in contrast to the intrinsic HVL associated with a particular beam which may be determined from Monte Carlo simulations.…”

Section: Introductionmentioning

confidence: 99%

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The variation of HVL with focal spot to chamber distance as a function of beam quality for the Pantak Therapax 150 X-ray unit and the implications on dose to water determination using the IPEMB code of practice

Baines

Sim

2014

Australas Phys Eng Sci Med

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Using a Pantak Therapax SXT 150 system HVL values for clinical beams generated with filters 4-8, were determined as a function of FCD (30-130 cm). Aluminium absorbers were placed midway between the focus and chamber with collimation to define both narrow and broad beam geometries. For filters 4-7 with broad beam geometry the HVL initially decreases as the FCD is increased from 30 cm and then increases as the FCD approaches 130 cm. In contrast filter 8 exhibits a reduction in HVL with increasing FCD attributed to the decreasing influence of absorber scatter. With narrow beam geometry the HVL of filter 4 increases as the FCD is increased. For other filters the HVL variation is similar to that for the broader beam albeit that for a given FCD the HVL is smaller, a consequence of reduced absorber scatter. Monte Carlo BEAMnrc simulations of filter 4-8 beams demonstrated a quality dependent air attenuation effect associated with an increase in HVL for lower quality beams with increasing FCD. Thus for the beams investigated in this work the variation of HVL with FCD can be interpreted in terms of the competing influences of absorber scatter, which tends to decrease the measured HVL, and a quality dependent in air attenuation that tends to increase the HVL with increasing FCD. In terms of an absorbed dose determination it is shown that changes of HVL with FCD resulted in variations of D w,z = 0 < ±0.5 %.

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Section: Hvl Determinationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The variation of HVL with focal spot to chamber distance as a function of beam quality for the Pantak Therapax 150 X-ray unit and the implications on dose to water determination using the IPEMB code of practice

Baines

Sim

2014

Australas Phys Eng Sci Med

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“…Podstawowymi parametrami określającymi właściwości osłonowe promieniowania jonizującego są HVL oraz TVL [5]. HVL (Half Value Layer) definiowany jest jako grubość materiału osłonowego wyrażona w cm, która powoduje osłabienie promieniowania o 50%, odpowiednio TVL (Tenth Value Layer) definiowany jest jako grubość materiału osłonowego wyrażona w cm, która powoduje osłabienie promieniowania o 90%.…”

Section: Badanie Osłonności Przed Promieniowaniem Gammaunclassified

Badanie Osłonności Radiacyjnej Betonów Specjalnych

et al. 2016

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BADANIE OSŁONNOŚCI RADIACYJNEJ BETONÓW SPECJALNYCHW artykule przedstawiono wyniki badań właściwości osłonnych betonów eksperymentalnych przed promieniowaniem gamma, z wykorzystaniem zamkniętego źródła promieniotwórczego 137 Cs. Do analiz sporządzono i opisano specjalne stanowisko badawcze o określonej geometrii. Do badań wykorzystano odpowiednio przygotowane próbki betonów ciężkich o zróżnicowanym składzie. W ramach prac przebadano piętnaście rodzajów betonów różniących się przede wszystkim zawartością kruszyw oraz gęstością objętościową. Na podstawie uzyskanych danych pomiarowych, dla poszczególnych prób betonów, otrzymano wartości grubości kolejnych warstw połówkowych (HVL) i dziesięciochłonnych (TVL). Z przeprowadzonych analiz wynika, iż najlepsze parametry osłonne w polu promieniowania gamma dla izotopu 137 Cs mają betony, z których kruszywem magnetytowym oraz barytowym. Betony te miały bardzo wysoką gęstość -powyżej 3300 kg/m 3 . Gorszymi parametrami charakteryzowały się natomiast mieszanki zawierające w skła-dzie tylko kruszywa zwykłe (serpentynit lub amfibolit), a ich gęstość nie przekraczała 2450 kg/m 3 . Otrzymane wyniki badań, zgodnie z wcześniejszymi założenia-mi, wskazują, że wraz ze wzrostem gęstości materiału osłonowego warstwa HVL (odpowiednio TVL) zmniejsza się, co oznacza, że właściwości osłonowe materiału przed promieniowaniem gamma ulegają poprawie.Słowa kluczowe: beton, osłony, promieniowanie gamma, pomiary eksperymentalne 1 Autor do korespondencji/corresponding author: Agnieszka Burakowska, Narodowe Centrum Badań Jądrowych,

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“…According to E.D. Trout 4) who made the detail investigation on the variation of HVL with diameter of irradiated filter, with focal-filter and focal-chamber distances, the more detail investigation will be done.…”

Section: Characteristics Of X-ray Reference Radiationmentioning

confidence: 99%

Establishment of Filtered X-ray Reference Radiation Based on ISO4037-1:1996 in CIRP

Zhang¹,

Minchen²,

Yawen³

et al. 2008

Journal of Nuclear Science and Technology

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According to the recommendations of ISO4037-1:1996, we have established the filtered x-ray reference radiation of low air kerma rate series (10 reference radiations), narrow spectrum series (13 reference radiations ), wide spectrum series (7 reference radiations) and high air kerma rate series (8 reference radiations) in CIRP. The relevant calibration facilities, such as ISO water phantom, are also built for calibration practice. An Yxlon MG325 is used as x-ray generator. Totally 38 reference radiations are produced with tube voltage range from 15 kV to 300 kV. The characteristics, such as HVL (half value layer), for these reference radiations are investigated. They are well consistent with the recommendations of ISO and can be used for the calibration of dose & doserate meters for radiation protection purpose.

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Determination of Half-Value Layer

Cited by 20 publications

References 0 publications

The variation of HVL with focal spot to chamber distance as a function of beam quality for the Pantak Therapax 150 X-ray unit and the implications on dose to water determination using the IPEMB code of practice

The variation of HVL with focal spot to chamber distance as a function of beam quality for the Pantak Therapax 150 X-ray unit and the implications on dose to water determination using the IPEMB code of practice

Badanie Osłonności Radiacyjnej Betonów Specjalnych

Establishment of Filtered X-ray Reference Radiation Based on ISO4037-1:1996 in CIRP

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