Organ dose conversion coefficients for voxel models of the reference male and female from idealized photon exposures

Schlattl, Helmut; Zankl, M.; Petoussi-Henss, Nina

doi:10.1088/0031-9155/52/8/006

Cited by 88 publications

(77 citation statements)

References 23 publications

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“…So far, no newly calculated conversion coefficients based on ICRP Publication 103 have been published by ICRU or ICRP. Calculations by Schlattl et al (10) have shown that the effect for photons are expected to be modest. It is recommended to continue to use the coefficients of ICRP Publication 74 for the time being.…”

Section: Concept Of Radiation Protection Quantitiesmentioning

confidence: 98%

“…For individual monitoring, the operational quantity is the personal dose equivalent, (10) and H p (0.07) are defined in the body of each person considered, their values vary from one person to another and also depend on the location on the body where the dosemeter is worn. In a non-isotropic radiation field, the value of personal dose equivalent also depends on the orientation of the person in this field.…”

Section: Operational Quantities For Individual Monitoring H P (D)mentioning

confidence: 99%

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Individual monitoring at accelerator centres

Wernli

2009

Radiation Protection Dosimetry

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The accurate determination of personal dose equivalent requires the proper use of appropriate radiological quantities and units, knowledge of the dose equivalent response of the personal dosemeters used and detailed information on the fluence as well as dose equivalent spectra at the workplaces. This information can then be used to select the appropriate dosemeters, to set up the optimum calibration conditions and to introduce, in case of need, normalisation factors for application in specific radiation fields. High-energy neutrons contribute significantly to the radiation fields around high-energy particle accelerators. Examples for procedures and methods to determine personal dose equivalent at accelerator centres are given.

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Section: Concept Of Radiation Protection Quantitiesmentioning

confidence: 98%

Section: Operational Quantities For Individual Monitoring H P (D)mentioning

confidence: 99%

Individual monitoring at accelerator centres

Wernli

2009

Radiation Protection Dosimetry

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“…Most of Organ absorbed doses per unit air kerma free in air from Pelvis-CT and Pelvis-Photo pelvic model are lower than those of ICRP Publication 74, which is caused by the difference in trunk thickness and organ position between different models. 22,23) The discrepancies decreased for the photon beams with higher energies which have higher penetrating power. The overall trend of conversion coefficients from kerma free-in-air to organ absorbed doses in the Pelvis-CT model agreed better with those from the ICRP Publication 74 data than those from Pelvis-Photo.…”

Section: )mentioning

confidence: 98%

“…When creating the Monte Carlo input file, the density and the elemental components were the most important physical property of voxel model, and need to be assigned to voxel. The density was acquired from ICRP Publication 23,10) and the elemental composition was acquired from ICRU Report 44. 11) In the Pelvis-Photo model, voxels that belong to the same organ or tissue had the same density.…”

Section: Constructing the Voxel Model (1) Construction Of Pelvis-photmentioning

confidence: 99%

Construction of a Voxel Model from CT Images with Density Derived from CT Numbers

Cheng

Qin

Cao

et al. 2011

Progress in Nuclear Science and Technology

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The voxel models representing human anatomy have been developed to calculate dose distribution in human body, while the density and elemental composition are the most important physical properties of voxel model. Usually, when creating the Monte Carlo input files, the average tissue densities recommended in ICRP Publication were used to assign each voxel in the existing voxel models. As each tissue consists of many voxels with different densities, the conventional method of average tissue densities failed to take account of the voxel's discrepancy, and therefore could not represent human anatomy faithfully. To represent human anatomy more faithfully, a method was implemented to assign each voxel, the densities of which were derived from CT number. In order to compare with the traditional method, we constructed two models from the cadaver specimen dataset. A CT-based pelvic voxel model called Pelvis-CT model was constructed, the densities of which were derived from the CT numbers. A color photograph-based pelvic voxel model called Pelvis-Photo model was also constructed, the densities of which were taken from ICRP Publication. The CT images and the color photographs were obtained from the same female cadaver specimen. The Pelvis-CT and Pelvis-Photo models were both ported into Monte Carlo code MCNP to calculate the conversion coefficients from kerma free-in-air to absorbed dose for external monoenergetic photon beams with energies of 0.1, 1 and 10 MeV under anterior-posterior (AP) geometry. The results were compared with those of given in ICRP Publication 74. Differences of up to 50% were observed between conversion coefficients of Pelvis-CT and Pelvis-Photo models, moreover the discrepancies decreased for the photon beams with higher energies. The overall trend of conversion coefficients of the Pelvis-CT model agreed well with that of ICRP Publication 74 data.

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“…Dosimetry for CT devices is mostly limited to measurements of so‐called computed tomography dose index (CTDI) values and various dose conversion factors 1 , 2 , 3 , 4 . These conversion factors are usually obtained with Monte Carlo simulations, which are calibrated themselves again with CTDI measurements.…”

Section: Introductionmentioning

confidence: 99%

Computed tomography dosimetry with high‐resolution detectors commonly used in radiotherapy — an energy dependence study

Liebmann

Poppe

Boetticher

2015

J Applied Clin Med Phys

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New methods of dosimetry in computed tomography (CT) X‐ray fields require the use of high‐resolution detectors instead of pencil‐type ionization chambers typically used for CT dose index (CTDI) measurements. This paper presents a study on the suitability of a wide range of ionization chambers, diodes, and a two‐dimensional detector array, used primarily in radiation therapy, for CT and cone‐beam CT dosimetry. Specifically, the energy dependence of these detectors from 50 kVp up to 125 kVp is reported. All measurements were performed in reference to a calibrated diode for use in this energy region. The radiation quality correction factors provided by the manufacturer were used, depending on the measured half‐value layer (HVL) for the particular X‐ray beam. Our study demonstrated the general usability of thimble ionization chambers. These thimble ionization chambers showed a maximum variation in energy response of 5%. Ionization chambers with even smaller sensitive volume, and which exhibit similar variation in energy dependence, can be used if higher spatial resolution is required. Furthermore, the investigated detectors are better suited for dosimetry at CT and CBCT units than conventional large volume or flat detectors, due to their rotational symmetry. Nevertheless, a flat detector can be used for certain measurement tasks, such as the acquisition of percent depth‐dose curves or beam profiles for nonrotating beams, which are important for beam characterization.PACS numbers: 87.57.uq, 87.56.Da, 87.57.Q‐

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Organ dose conversion coefficients for voxel models of the reference male and female from idealized photon exposures

Cited by 88 publications

References 23 publications

Individual monitoring at accelerator centres

Individual monitoring at accelerator centres

Construction of a Voxel Model from CT Images with Density Derived from CT Numbers

Computed tomography dosimetry with high‐resolution detectors commonly used in radiotherapy — an energy dependence study

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