Dose conversion coefficients for monoenergetic electrons incident on a realistic human eye model with different lens cell populations

Nogueira, Pedro; Zankl, M.; Schlattl, Helmut; Vaz, P.

doi:10.1088/0031-9155/56/21/010

Cited by 33 publications

(37 citation statements)

References 28 publications

(58 reference statements)

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“…It is considered that the mathematical model used in traditional articles by P. Nogueira et al (2011) [20] and R. Behrens (2009) [21] was better than the mathematical model developed in this study in terms of geometrical elements and material composition. However, whereas the mathematical model for eyes was restricted in one and the traditional studies were performed by preparing a model of the orbit (the bone structure surrounding the eyes), this study intended to perform a more practical study with a model more properly suited to evaluate the radiation exposure of the eyes accompanying a brain CT by preparing two eyes along with the cranium (brain part).…”

Section: Composition Of the Mathematical Phantommentioning

confidence: 74%

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Evaluation of radiation exposure upon visual organs during a head CT scan

Kim

Lim

Chung

2012

Journal of Nuclear Science and Technology

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In order to analyze and compare the absorbed radiation dose and dose rate of visual organs (eyes, corneas, and lenses) of the head with the surrounding areas of the head during CT scans, a mathematical head phantom was created. In addition, the amount of radiation exposure reduced when using an eye shield was also analyzed. According to the results, it was found that the absorbed dose was highest when using 120 kV (as compared to 80 kV and 100 kV) and the absorbed dose rate of the visual organs compared to the head was about 1.35% for the eyes, 0.9% for the corneas, and 0.095% for the lenses. Finally, it was shown that the dose reduction rate of each organ when using an eye shield was about 24% for the eyes, about 22% for the corneas, and more than 40% for the lenses.

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Section: Composition Of the Mathematical Phantommentioning

confidence: 74%

“…As there was a previous example by Jonathan Bristol [19] in 2010 and P. Nogueira et al [20] in 2011 assessing the radiation dose on the eyes using MCNP (Monte Carlo Particle Transport) code, we also chose to use MCNPX for calculating the amount of photon transport and energy deposition.…”

Section: Monte Carlo Calculationmentioning

confidence: 99%

Evaluation of radiation exposure upon visual organs during a head CT scan

Kim

Lim

Chung

2012

Journal of Nuclear Science and Technology

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“…In the present work, a detailed model of the eye, which provides the geometry and composition of different zones of the lens and other eye substructures such as anterior chamber, cornea, sclera, choroid, retina, and vitreous humor, was considered (Nogueira et al 2011). Figure 1 displays schematic two-dimensional and three-dimensional views of the Nogueira eye model used in the present work, in comparison with the AM eye model which is usually included in the ICRP male reference phantom.…”

Section: Eye Structurementioning

confidence: 99%

“…In recent years, different eye models were presented based on the differences in sensitivity of eye zones (Alghamdi et al 2007;Behrens et al 2009;Nogueira et al 2011;Caracappa et al 2014). Till now, these models have been widely used for calculation of dose conversion coefficients of the eye lens (Behrens et al 2009;Behrens and Dietze 2010;Nogueira et al 2011;Manger et al 2012;Sakhaee et al 2015;Vejdani-Noghreiyan and EbrahimiKhankook 2016).…”

Section: Introductionmentioning

confidence: 99%

“…Till now, these models have been widely used for calculation of dose conversion coefficients of the eye lens (Behrens et al 2009;Behrens and Dietze 2010;Nogueira et al 2011;Manger et al 2012;Sakhaee et al 2015;Vejdani-Noghreiyan and EbrahimiKhankook 2016). One of the most detailed models is the one designed by Nogueira and co-workers, in which lens cells were divided into sensitive and insensitive, and GZ was considered as the sensitive zone to ionizing radiation (Nogueira et al 2011).…”

Section: Introductionmentioning

confidence: 99%

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The effects of simulating a realistic eye model on the eye dose of an adult male undergoing head computed tomography

Akhlaghi

Ebrahimi-Khankook

Vejdani-Noghreiyan

2017

Radiat Environ Biophys

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In head computed tomography, radiation upon the eye lens (as an organ with high radiosensitivity) may cause lenticular opacity and cataracts. Therefore, quantitative dose assessment due to exposure of the eye lens and surrounding tissue is a matter of concern. For this purpose, an accurate eye model with realistic geometry and shape, in which different eye substructures are considered, is needed. To calculate the absorbed radiation dose of visual organs during head computed tomography scans, in this study, an existing sophisticated eye model was inserted at the related location in the head of the reference adult male phantom recommended by the International Commission on Radiological Protection (ICRP). Then absorbed doses and distributions of energy deposition in different parts of this eye model were calculated and compared with those based on a previous simple eye model. All calculations were done using the Monte Carlo code MCNP4C for tube voltages of 80, 100, 120 and 140 kVp. In spite of the similarity of total dose to the eye lens for both eye models, the dose delivered to the sensitive zone, which plays an important role in the induction of cataracts, was on average 3% higher for the sophisticated model as compared to the simple model. By increasing the tube voltage, differences between the total dose to the eye lens between the two phantoms decrease to 1%. Due to this level of agreement, use of the sophisticated eye model for patient dosimetry is not necessary. However, it still helps for an estimation of doses received by different eye substructures separately.

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Dose rate conversion coefficients for ocular contamination in nuclear medicine: A Monte Carlo simulation with experimental validation

Hoeijmakers,

Hoenen,

Bauwens

et al. 2024

Medical Physics

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BackgroundSince 2011, the International Commission on Radiological Protection (ICRP) has recommended an annual eye lens dose limit of 20 mSv for radiation workers, averaged over 5 years, with no year exceeding 50 mSv. However, limited research has been conducted on dose rate conversion coefficients (DCCs) for direct contamination of the eye.PurposeThis study aimed to accurately determine DCCs for the eye lens and cornea for ocular contamination with radionuclides used in nuclear medicine.MethodsDCCs for 37 radionuclides used in nuclear medicine were determined using two different methods. Method 1 involved conducting Monte Carlo (MC) simulations of an ICRU cylinder to determine the absorbed dose at a depth of 3 mm resulting from a point source. The accuracy of this simulation approach was validated by experimental thermoluminescent dosimeter (TLD) measurements for 18F, 68Ga, 99mTc, and 177Lu. In method 2, average DCCs were calculated for the eye lens (complete and radiosensitive parts) and the cornea for both a point source and thin surface contamination centered on the cornea using MC simulations on the adult mesh‐type reference computational phantom of the eye from the ICRP (MRCP).ResultsDCCs determined from TLD measurements showed excellent agreement (deviations: +1.4%, +4.7%, −3.1%, and −2.5% for 18F, 68Ga, 99mTc, and 177Lu, respectively) compared to MC simulations of the experimental set‐up. For the 37 radionuclides, DCCs of the complete eye‐lens for a point source ranged from 2.53 × 10−7 to 4.15 × 10−2 mGy MBq−1 s−1 for the adult MRCPs, being substantially smaller compared to DCCs determined via MC simulations of a ICRU cylinder. In general, point source and surface contamination showed comparable DCCs for the eye lens. Radionuclides emitting low‐energy beta radiation or conversion electrons (e.g., 177Lu, 99mTc) showed low DCCs as the radiation does not penetrate to the depth of the eye lens, while radionuclides emitting high‐energy beta radiation (e.g., 90Y) showed high DCCs. Overall, DCCs for the radiosensitive part of the eye lens were larger (up to a factor of 3) compared to the complete eye lens. DCCs for the cornea were larger than for the eye lens with a factor that strongly depended on the emitted radiation type. Especially alpha emitters (e.g., 211At, 223Ra) showed high DCCs for the cornea because of the short range of alpha radiation, leading to local maxima in the cornea and not reaching the eye lens.ConclusionDCCs at a depth of 3 mm in an ICRU cylinder and adult MRCP DCCs for both the complete and sensitive parts of the eye lens and cornea were determined for 37 radionuclides having applications in nuclear medicine. These DCCs are highly useful in radiation safety assessments and radiation dose calculations in ocular contamination incidents.

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Dose conversion coefficients for monoenergetic electrons incident on a realistic human eye model with different lens cell populations

Cited by 33 publications

References 28 publications

Evaluation of radiation exposure upon visual organs during a head CT scan

Evaluation of radiation exposure upon visual organs during a head CT scan

The effects of simulating a realistic eye model on the eye dose of an adult male undergoing head computed tomography

Dose rate conversion coefficients for ocular contamination in nuclear medicine: A Monte Carlo simulation with experimental validation

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