Average glandular dose in digital mammography and digital breast tomosynthesis: comparison of phantom and patient data

NARCIS (Netherlands)

Bouwman, R. W.; van Engen, R. E.; Young, K. C.; den Heeten, G. J.; Broeders, M. J. M.; Schopphoven, S.; Jeukens, C. R. L. P. N.; Veldkamp, W. J. H.; Dance, D. R.

2015-01-01

For the evaluation of the average glandular dose (AGD) in digital mammography (DM) and digital breast tomosynthesis (DBT) phantoms simulating standard model breasts are used. These phantoms consist of slabs of polymethyl methacrylate (PMMA) or a combination of PMMA and polyethylene (PE). In the last

Assessment of Mean Glandular Dose in Mammography System with Different Anode-Filter Combinations Using MCNP Code.

Science.gov (United States)

Gholamkar, Lida; Mowlavi, Ali Asghar; Sadeghi, Mahdi; Athari, Mitra

2016-10-01

X-ray mammography is one of the general methods for early detection of breast cancer. Since glandular tissue in the breast is sensitive to radiation and it increases the risk of cancer, the given dose to the patient is very important in mammography. The aim of this study was to determine the average absorbed dose of X-ray radiation in the glandular tissue of the breast during mammography examinations as well as investigating factors that influence the mean glandular dose (MGD). One of the precise methods for determination of MGD absorbed by the breast is Monte Carlo simulation method which is widely used to assess the dose. We studied some different X-ray sources and exposure factors that affect the MGD. "Midi-future" digital mammography system with amorphous-selenium detector was simulated using the Monte Carlo N-particle extended (MCNPX) code. Different anode/filter combinations such as tungsten/silver (W/Ag), tungsten/rhodium (W/Rh), and rhodium/aluminium (Rh/Al) were simulated in this study. The voltage of X-ray tube ranged from 24 kV to 32 kV with 2 kV intervals and the breast phantom thickness ranged from 3 to 8 cm, and glandular fraction g varied from 10% to 100%. MGD was measured for different anode/filter combinations and the effects of changing tube voltage, phantom thickness, combination and glandular breast tissue on MGD were studied. As glandular g and X-ray tube voltage increased, the breast dose increased too, and the increase of breast phantom thickness led to the decrease of MGD. The obtained results for MGD were consistent with the result of Boone et al. that was previously reported. By comparing the results, we saw that W/Rh anode/filter combination is the best choice in breast mammography imaging because of the lowest delivered dose in comparison with W/Ag and Rh/Al. Moreover, breast thickness and g value have significant effects on MGD.

Glandularity estimation in Japanese women by using a breast model made from mammographic findings of European women

International Nuclear Information System (INIS)

Kawaguchi, Ai; Matsunaga, Yuta; Chida, Koichi; Asada, Yasuki; Suzuki, Shoichi

2016-01-01

This study aimed to estimate breast glandularity in Japanese women using patient exposure conditions and tissue-equivalent materials by a conventional method. Typical glandularities in Japanese women were compared with those in European women to verify the validity of the average glandular dose estimation manual based on the EUREF protocol. Glandularity was estimated from the data of 600 patients and the model breast of the tissue-equivalent materials which had various amounts of glandular contents and thicknesses. The model breasts were measured to examine the relationships between the thickness of the glandular contents and tube loading by using an automatic exposure control system. Then, equations were established to determine glandularity from patient data. The mean glandularity in the highest compressed breast thickness (CBT) group of 36–45 mm was 72%. The mean CBT of the 184 (31%) patients with glandularities exceeding 100% was 31 mm. Glandularities in patients with CBT of 30–70 mm in the present study were higher compared to those in European women by approximately 10–20%. The results suggest that the model breast of European women might not be a suitable reference standard for more than 30% of Japanese women, who have breasts with lower CBT. (author)

Comportamento da dose glandular versus contraste do objeto em mamografia: determinação de formalismo semi-empírico para diferentes combinações alvo-filtro Behavior of subject contrast versus glandular dose in mammography: determination of a semi-empirical formalism for different target-filter combinations

Directory of Open Access Journals (Sweden)

Gabriela Hoff

2006-06-01

Full Text Available OBJETIVO: Verificar o efeito da mudança no contraste do objeto, tempo de exposição e dose de radiação quando diferentes espessuras de filtração de molibdênio (Mo e ródio (Rh são empregadas em mamógrafos. MATERIAIS E MÉTODOS: Realizaram-se medidas da exposição na entrada da pele com uma câmara de ionização para diferentes espessuras para os filtros de Mo e Rh. Para determinar a dose glandular média foi utilizado simulador de BR12 (50% tecido adiposo e 50% tecido glandular de diferentes espessuras (4 cm e 8 cm. Energias na faixa de 24 kVp a 34 kVp foram empregadas e filmes Kodak MinR 2000 foram utilizados. RESULTADOS: Os resultados evidenciaram dados de contraste do objeto, dose glandular e tempo de exposição para diferentes espessuras de filtros adicionais e diferentes tensões. Esses dados indicaram aumento nos valores de contraste do objeto e tempo de exposição, com o aumento da espessura dos filtros. A dose glandular apresentou comportamento com diferentes tendências para cada caso analisado. Equações foram definidas para possibilitar a estimativa do contraste do objeto, dose glandular e tempo de exposição para os casos estudados. CONCLUSÃO: Os resultados possibilitaram a estimativa de equações que auxiliam na verificação do comportamento do contraste do objeto e da dose glandular para simuladores com espessura de 4 cm e 8 cm e para os filtros de Rh e Mo. Dessa forma, torna-se possível estimar a figura de mérito (razão entre o contraste do objeto e a dose glandular, podendo auxiliar na análise da relação risco-benefício dos casos estudados.OBJECTIVE: Our purpose was to verify the effect of changes in subject contrast, exposure time and radiation dose when different thicknesses of molybdenum (Mo and rhodium (Rh filters are used in mammography equipments. MATERIALS AND METHODS: Entrance skin exposure measurements were performed with an ionization chamber for different thicknesses of Mo and Rh filters

Evaluation of average glandular dose in mammography services in 10 cities of Colombia; Avaliacao de dose glandular media em servicos de mamografia de 10 cidades de Colombia

Energy Technology Data Exchange (ETDEWEB)

Alejo-Martinez, H.; Salazar-Hurtado, E.; Puerto-Jimenez, D. [Grupo de Prevencion Temprana Del Cancer, Instituto Nacional de Cancerologia, Bogota D.C. (Colombia)

2016-07-01

The objective of this study was to conduct an assessment of dose in 60 mammography services that have screening programs for breast cancer in 10 cities of Colombia. The third quartile of the average glandular dose was 2,29 mGy, range between 1,0 and 5,6 mGy, for the phantom equivalent to a standard breast. This study included mammography units with conventional and digital technology. (author)

Impact of digitalization of mammographic units on average glandular doses in the Flemish Breast Cancer Screening Program

OpenAIRE

De Hauwere, An; Thierens, Hubert

2012-01-01

The impact of digitalization on the average glandular doses in 49 mammographic units participating in the Flemish Breast Cancer Screening Program was studied. Screen-film was changed to direct digital radiography and computed radiography in 25 and 24 departments respectively. Average glandular doses were calculated before and after digitalization for different PMMA-phantom thicknesses and for groups of 50 successive patients. For the transition from screen-film to computed radiography both ph...

Evaluation of average glandular dose in digital and conventional systems of the mammography; Avaliacao da dose glandular media em sistemas digitais e convencionais de mamografia

Energy Technology Data Exchange (ETDEWEB)

Xavier, Aline C.S.; Barros, Vinicius S.M.; Khoury, Hellen J., E-mail: alinecx90@gmail.com, E-mail: vsmdbarros@gmail.com, E-mail: hjkhoury@gmail.com [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil). Dept. de Energia Nuclear; Mello, Francisca A. de, E-mail: francissamello@yahoo.com.br [Hospital das Clinicas do Recife (HCR/UFPE), PE (Brazil)

2014-07-01

Mammography is currently the most effective method of diagnosis and detection of breast pathologies. The main interest in this kid of exam comes from the high incidence rate of breast cancer and necessity of high quality images for accurate diagnosis. Digital mammography systems have several advantages compared to conventional systems, however the use of digital imaging systems is not always integrated to an image acquisition protocol. Therefore, it is questionable if digital systems truly reduce the dose received by the patient, because many times is introduced in the clinics without optimization of the image acquisition protocols. The aim of this study is to estimate the value of incident air Kerma and average glandular dose (AGD) in patients undergoing conventional and digital mammography systems in Recife. This study was conducted with 650 patients in three hospitals. The value of incident air Kerma was estimated from the measurement of the yield of equipment and irradiation parameters used for each patient. From these results and using the methodology proposed by Dance et al. the value of the average glandular dose was calculated. The results obtained show that the lowest value of AGD was found with conventional screen-film system, indicating that the parameters for image acquisition with digital systems are not optimized. It was also observed that the institutions with digital systems use lower breast compression values than the conventional. (author)

Preliminary results of the average glandular dose to the breast with TLDS measure is computed as the conversion factors

International Nuclear Information System (INIS)

Sardo, Luiz T.L.; Almeida, Claudio D.; Coutinho, Celia M.C.

2013-01-01

At mammography exams there is a risk of a breast cancer induced from the absorbed dose by the glandular tissue. According to the National Institute of Cancer, INCA, breast cancer is the second type most frequent in the world and the most common among women, therefore the necessity of monitoring the mean glandular dose, D G . Measuring methods of D G were established by some authors. Among the established methods the method of Dance is one of the most known. In this study was utilized a measurement method realized with TL dosimeters inserted in a breast tissue equivalent phantom, BTE, with 46% of glandularity and exposed using Mo/Mo and Mo/Rh target/filter combination and 28kV. To ensure this measurement method the results were compared with a calculation method, used by Dance, of D G from the measurement of incident air kerma, K i , and conversion factors to consider mainly the beam quality, the compressed thickness and the glandularity of the breast. The results of the comparison of the D G measurement with the obtained dose by the method of Dance demonstrated that for the thickness of 4.0 and 6.0 cm the doses were consistent. For the thickness of 5.0 cm the difference was higher, indicating that the glandularity may influence, suggesting further investigation. (author)

MO-F-CAMPUS-I-02: Accuracy in Converting the Average Breast Dose Into the Mean Glandular Dose (MGD) Using the F-Factor in Cone Beam Breast CT- a Monte Carlo Study Using Homogeneous and Quasi-Homogeneous Phantoms

Energy Technology Data Exchange (ETDEWEB)

Lai, C; Zhong, Y; Wang, T; Shaw, C [UT MD Anderson Cancer Center, Houston, TX (United States)

2015-06-15

Purpose: To investigate the accuracy in estimating the mean glandular dose (MGD) for homogeneous breast phantoms by converting from the average breast dose using the F-factor in cone beam breast CT. Methods: EGSnrc-based Monte Carlo codes were used to estimate the MGDs. 13-cm in diameter, 10-cm high hemi-ellipsoids were used to simulate pendant-geometry breasts. Two different types of hemi-ellipsoidal models were employed: voxels in quasi-homogeneous phantoms were designed as either adipose or glandular tissue while voxels in homogeneous phantoms were designed as the mixture of adipose and glandular tissues. Breast compositions of 25% and 50% volume glandular fractions (VGFs), defined as the ratio of glandular tissue voxels to entire breast voxels in the quasi-homogeneous phantoms, were studied. These VGFs were converted into glandular fractions by weight and used to construct the corresponding homogeneous phantoms. 80 kVp x-rays with a mean energy of 47 keV was used in the simulation. A total of 109 photons were used to image the phantoms and the energies deposited in the phantom voxels were tallied. Breast doses in homogeneous phantoms were averaged over all voxels and then used to calculate the MGDs using the F-factors evaluated at the mean energy of the x-rays. The MGDs for quasi-homogeneous phantoms were computed directly by averaging the doses over all glandular tissue voxels. The MGDs estimated for the two types of phantoms were normalized to the free-in-air dose at the iso-center and compared. Results: The normalized MGDs were 0.756 and 0.732 mGy/mGy for the 25% and 50% VGF homogeneous breasts and 0.761 and 0.733 mGy/mGy for the corresponding quasi-homogeneous breasts, respectively. The MGDs estimated for the two types of phantoms were similar within 1% in this study. Conclusion: MGDs for homogeneous breast models may be adequately estimated by converting from the average breast dose using the F-factor.

MO-F-CAMPUS-I-02: Accuracy in Converting the Average Breast Dose Into the Mean Glandular Dose (MGD) Using the F-Factor in Cone Beam Breast CT- a Monte Carlo Study Using Homogeneous and Quasi-Homogeneous Phantoms

International Nuclear Information System (INIS)

Lai, C; Zhong, Y; Wang, T; Shaw, C

2015-01-01

Purpose: To investigate the accuracy in estimating the mean glandular dose (MGD) for homogeneous breast phantoms by converting from the average breast dose using the F-factor in cone beam breast CT. Methods: EGSnrc-based Monte Carlo codes were used to estimate the MGDs. 13-cm in diameter, 10-cm high hemi-ellipsoids were used to simulate pendant-geometry breasts. Two different types of hemi-ellipsoidal models were employed: voxels in quasi-homogeneous phantoms were designed as either adipose or glandular tissue while voxels in homogeneous phantoms were designed as the mixture of adipose and glandular tissues. Breast compositions of 25% and 50% volume glandular fractions (VGFs), defined as the ratio of glandular tissue voxels to entire breast voxels in the quasi-homogeneous phantoms, were studied. These VGFs were converted into glandular fractions by weight and used to construct the corresponding homogeneous phantoms. 80 kVp x-rays with a mean energy of 47 keV was used in the simulation. A total of 109 photons were used to image the phantoms and the energies deposited in the phantom voxels were tallied. Breast doses in homogeneous phantoms were averaged over all voxels and then used to calculate the MGDs using the F-factors evaluated at the mean energy of the x-rays. The MGDs for quasi-homogeneous phantoms were computed directly by averaging the doses over all glandular tissue voxels. The MGDs estimated for the two types of phantoms were normalized to the free-in-air dose at the iso-center and compared. Results: The normalized MGDs were 0.756 and 0.732 mGy/mGy for the 25% and 50% VGF homogeneous breasts and 0.761 and 0.733 mGy/mGy for the corresponding quasi-homogeneous breasts, respectively. The MGDs estimated for the two types of phantoms were similar within 1% in this study. Conclusion: MGDs for homogeneous breast models may be adequately estimated by converting from the average breast dose using the F-factor

Glandular dose in breast tomosynthesis examinations: Preliminary study with a sample of patients

International Nuclear Information System (INIS)

Castillo, M.; Chevalier, M.; Calzado, A.; Valverde, J.

2013-01-01

The aim of this study is to analyze the mean glandular dose administered to a group of patients with a tomography system (Selenia Dimensions) service installed on a large hospital in which routine tests are done and screening. (Author)

Estimate of average glandular dose (AGD) in national clinics of mammography

International Nuclear Information System (INIS)

Mora, Patricia; Segura, Helena

2004-01-01

The breast cancer represents the second cause of death by cancer in the femme population of our country. The specialized equipment for the obtaining of the mammographic images is higher every day and its use increases daily. The quality of the radiographic study is linked to the dose that this tissue intrinsically sensible receives to the ionizing radiations. The present work makes the first national study to quantify the average glandular doses and to connect them with the diagnostic quality and the recommendations to international scale. (Author) [es

Average glandular dose in routine mammography screening using a Sectra Microdose Mammography unit

International Nuclear Information System (INIS)

Hemdal, B.; Herrnsdorf, L.; Andersson, I.; Bengtsson, G.; Heddson, B.; Olsson, M.

2005-01-01

The Sectra MicroDose Mammography system is based on direct photon counting (with a solid-state detector), and a substantially lower dose to the breast than when using conventional system can be expected. In this work absorbed dose measurements have been performed for the first unit used in routine mammography screening (at the Hospitals of Helsingborg (Sweden)). Two European protocols on dosimetry in mammography have been followed. Measurement of half value layer (HVL) cannot be performed as prescribed, but this study has demonstrated than non-invasive measurements of HVL can be performed accurately with a sensitive and well collimated solid-state detector with simultaneous correction for the energy dependence. The average glandular dose for a 50 mm standard breast with 50% glandularity, simulated by 45 mm polymethylmethacrylate, was found to be 0.21 and 0.28 mGy in March and December 2004, respectively. These values are much lower than for any other mammography system on the market today. It has to be stressed that the measurement were made using the current clinical settings and that no systematic optimisation of the relationship between absorbed dose and diagnostic image quality has been performed within the present study. In order to further increase the accuracy of absorbed dose measurements for this unit, the existing dose protocols should be revised to account also for the tungsten/aluminium anode/filter combination, the multi-slit pre-collimator device and the occurrence of a dose profile in the scanning direction. (authors)

Evaluation of average glandular dose in mammography services in 10 cities of Colombia

International Nuclear Information System (INIS)

Alejo-Martinez, H.; Salazar-Hurtado, E.; Puerto-Jimenez, D.

2016-01-01

The objective of this study was to conduct an assessment of dose in 60 mammography services that have screening programs for breast cancer in 10 cities of Colombia. The third quartile of the average glandular dose was 2,29 mGy, range between 1,0 and 5,6 mGy, for the phantom equivalent to a standard breast. This study included mammography units with conventional and digital technology. (author)

Comparison of average glandular dose in screen-film and digital mammography using breast tissue-equivalent phantom

International Nuclear Information System (INIS)

Shin, Gwi Soon; Kim, Jung Min; Kim, You Hyun; Choi, Jong Hak; Kim, Chang Kyun

2007-01-01

In recent years, mammography system is changed rapidly from conventional screen-film system to digital system for application to screening and diagnosis. Digital mammography system provides several advantages over screen-film mammography system. According to the information provided by the manufacturer, digital mammography system offers radiation dose reduction in comparison with screen-film mammography system, because of digital detector, particularly direct digital detector has higher x-ray absorption efficiency than screen-film combination or imaging plate (IP). We measured average glandular doses (ADG) in screen-film mammography (SFM) system with slow screen-film combination, computed mammography (CM) system, indirect digital mammography (IDM) system and direct digital mammography (DDM) system using breast tissue-equivalent phantom (glandularity 30%, 50% and 70%). The results were shown as follows: AGD values for DDM system were highest than those for other systems. Although automatic exposure control (AEC) mode was selected, the curve of the AGD values against thickness or glandularity increased significantly for the SFM system with the uniform target/filter (Mo/Mo) combination. Therefore, the AGD values for the high energy examinations were highest in the SFM system, and those for the low energy examinations were highest in the DDM system. But the curve of the AGD values against thickness and glandularity increased gently for CM system with the automatic selection of the target/filter combination (from Mo/Mo to Mo/Rh or from Mo/Rh to Rh/Rh), and the AGD values were lowest. Consequently, the parameters in mammography for each exposure besides detection efficiency play an important role in order to estimate a patient radiation dose

Estimation of the average glandular dose on a team of tomosynthesis

International Nuclear Information System (INIS)

Nunez Martinez, L. M. R.; Sanchez Jimenez, J.; Pizarro trigo, F.

2013-01-01

Seeking to improve the information that gives us an image of mammography the manufacturers have implemented tomosynthesis. With this method of acquisition and reconstruction of image we went from having a 2D to a 3D image image, in such a way that it reduces or eliminates the effect of overlap of tissues. The estimate of the dose, which is always a fundamental parameter in the control of quality of radiology equipment, is more in the case of mammography by the radiosensitivity of this body and the frequency of their use. The objective of this work is the determination of the mean in a team glandular dose of with tomosynthesis mammography. (Author)

Method for determination of the mean fraction of glandular tissue in individual female breasts using mammography

International Nuclear Information System (INIS)

Jansen, J T M; Veldkamp, W J H; Thijssen, M A O; Woudenberg, S van; Zoetelief, J

2005-01-01

The nationwide breast cancer screening programme using mammography has been in full operation in the Netherlands since 1997. Quality control of the screening programme has been assigned to the National Expert and Training Centre for Breast Cancer Screening. Limits are set to the mean glandular dose and the centre monitors these for all facilities engaged in the screening programme. This procedure is restricted to the determination of the entrance dose on a 5 cm thick polymethylmethacrylate (PMMA) phantom. The mean glandular dose for a compressed breast is estimated from these data. Individual breasts may deviate largely from this 5 cm PMMA breast model. Not only may the compressed breast size vary from 2 to 10 cm, but breast composition varies also. The mean glandular dose is dependent on the fraction of glandular tissue (glandularity) of the breast. To estimate the risk related to individual mammograms requires the development of a method for determination of the glandularity of individual breasts. A method has been developed to derive the glandularity using the attenuation of mammography x-rays in the breast. The method was applied to a series of mammograms at a screening unit. The results, i.e., a glandularity of 93% within the range of 0 to 1, were comparable with data in the literature. The glandularity as a function of compressed breast thickness is similar to results from other investigators using differing methods

Effect of the glandular composition on digital breast tomosynthesis image quality and dose optimisation

International Nuclear Information System (INIS)

Marques, T.; Di Maria, S.; Vaz, P.; Ribeiro, A.; Belchior, A.; Cardoso, J.; Matela, N.; Oliveira, N.; Almeida, P.; Janeiro, L.

2015-01-01

In the image quality assessment for digital breast tomosynthesis (DBT), a breast phantom with an average percentage of 50 % glandular tissue is seldom used, which may not be representative of the breast tissue composition of the women undergoing such examination. This work aims at studying the effect of the glandular composition of the breast on the image quality taking into consideration different sizes of lesions. Monte Carlo simulations were performed using the state-of-the-art computer program PENELOPE to validate the image acquisition system of the DBT equipment as well as to calculate the mean glandular dose for each projection image and for different breast compositions. The integrated PENELOPE imaging tool (PenEasy) was used to calculate, in mammography, for each clinical detection task the X-ray energy that maximises the figure of merit. All the 2D cranial-caudal projections for DBT were simulated and then underwent the reconstruction process applying the Simultaneous Algebraic Reconstruction Technique. Finally, through signal-to-noise ratio analysis, the image quality in DBT was assessed. (authors)

Average glandular dose in digital mammography and breast tomosynthesis

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Olgar, T. [Ankara Univ. (Turkey). Dept. of Engineering Physics; Universitaetsklinikum Leipzig AoeR (Germany). Klinik und Poliklinik fuer Diagnostische und Interventionelle Radiologie; Kahn, T.; Gosch, D. [Universitaetsklinikum Leipzig AoeR (Germany). Klinik und Poliklinik fuer Diagnostische und Interventionelle Radiologie

2012-10-15

Purpose: To determine the average glandular dose (AGD) in digital full-field mammography (2 D imaging mode) and in breast tomosynthesis (3 D imaging mode). Materials and Methods: Using the method described by Boone, the AGD was calculated from the exposure parameters of 2247 conventional 2 D mammograms and 984 mammograms in 3 D imaging mode of 641 patients examined with the digital mammographic system Hologic Selenia Dimensions. The breast glandular tissue content was estimated by the Hologic R2 Quantra automated volumetric breast density measurement tool for each patient from right craniocaudal (RCC) and left craniocaudal (LCC) images in 2 D imaging mode. Results: The mean compressed breast thickness (CBT) was 52.7 mm for craniocaudal (CC) and 56.0 mm for mediolateral oblique (MLO) views. The mean percentage of breast glandular tissue content was 18.0 % and 17.4 % for RCC and LCC projections, respectively. The mean AGD values in 2 D imaging mode per exposure for the standard breast were 1.57 mGy and 1.66 mGy, while the mean AGD values after correction for real breast composition were 1.82 mGy and 1.94 mGy for CC and MLO views, respectively. The mean AGD values in 3 D imaging mode per exposure for the standard breast were 2.19 mGy and 2.29 mGy, while the mean AGD values after correction for the real breast composition were 2.53 mGy and 2.63 mGy for CC and MLO views, respectively. No significant relationship was found between the AGD and CBT in 2 D imaging mode and a good correlation coefficient of 0.98 in 3 D imaging mode. Conclusion: In this study the mean calculated AGD per exposure in 3 D imaging mode was on average 34 % higher than for 2 D imaging mode for patients examined with the same CBT.

Average glandular dose in digital mammography and breast tomosynthesis

International Nuclear Information System (INIS)

Olgar, T.; Universitaetsklinikum Leipzig AoeR; Kahn, T.; Gosch, D.

2012-01-01

Purpose: To determine the average glandular dose (AGD) in digital full-field mammography (2 D imaging mode) and in breast tomosynthesis (3 D imaging mode). Materials and Methods: Using the method described by Boone, the AGD was calculated from the exposure parameters of 2247 conventional 2 D mammograms and 984 mammograms in 3 D imaging mode of 641 patients examined with the digital mammographic system Hologic Selenia Dimensions. The breast glandular tissue content was estimated by the Hologic R2 Quantra automated volumetric breast density measurement tool for each patient from right craniocaudal (RCC) and left craniocaudal (LCC) images in 2 D imaging mode. Results: The mean compressed breast thickness (CBT) was 52.7 mm for craniocaudal (CC) and 56.0 mm for mediolateral oblique (MLO) views. The mean percentage of breast glandular tissue content was 18.0 % and 17.4 % for RCC and LCC projections, respectively. The mean AGD values in 2 D imaging mode per exposure for the standard breast were 1.57 mGy and 1.66 mGy, while the mean AGD values after correction for real breast composition were 1.82 mGy and 1.94 mGy for CC and MLO views, respectively. The mean AGD values in 3 D imaging mode per exposure for the standard breast were 2.19 mGy and 2.29 mGy, while the mean AGD values after correction for the real breast composition were 2.53 mGy and 2.63 mGy for CC and MLO views, respectively. No significant relationship was found between the AGD and CBT in 2 D imaging mode and a good correlation coefficient of 0.98 in 3 D imaging mode. Conclusion: In this study the mean calculated AGD per exposure in 3 D imaging mode was on average 34 % higher than for 2 D imaging mode for patients examined with the same CBT.

Evaluation of average glandular dose in digital and conventional systems of the mammography

International Nuclear Information System (INIS)

Xavier, Aline C.S.; Barros, Vinicius S.M.; Khoury, Hellen J.

2014-01-01

Mammography is currently the most effective method of diagnosis and detection of breast pathologies. The main interest in this kid of exam comes from the high incidence rate of breast cancer and necessity of high quality images for accurate diagnosis. Digital mammography systems have several advantages compared to conventional systems, however the use of digital imaging systems is not always integrated to an image acquisition protocol. Therefore, it is questionable if digital systems truly reduce the dose received by the patient, because many times is introduced in the clinics without optimization of the image acquisition protocols. The aim of this study is to estimate the value of incident air Kerma and average glandular dose (AGD) in patients undergoing conventional and digital mammography systems in Recife. This study was conducted with 650 patients in three hospitals. The value of incident air Kerma was estimated from the measurement of the yield of equipment and irradiation parameters used for each patient. From these results and using the methodology proposed by Dance et al. the value of the average glandular dose was calculated. The results obtained show that the lowest value of AGD was found with conventional screen-film system, indicating that the parameters for image acquisition with digital systems are not optimized. It was also observed that the institutions with digital systems use lower breast compression values than the conventional. (author)

Glandular dose in breast tomosynthesis examinations: Preliminary study with a sample of patients; Dosis glandular en examenes de tomosintesis de mama: estudio preliminar con una muestra de pacientes

Energy Technology Data Exchange (ETDEWEB)

Castillo, M.; Chevalier, M.; Calzado, A.; Valverde, J.

2013-07-01

The aim of this study is to analyze the mean glandular dose administered to a group of patients with a tomography system (Selenia Dimensions) service installed on a large hospital in which routine tests are done and screening. (Author)

Mean glandular dose measurement on various breast phantom using mammography machine in MINT Medical Physics Laboratory

International Nuclear Information System (INIS)

Wan Hazlinda Ismail; Asmaliza Hashim; Abd Aziz Mhd Ramli

2005-01-01

Until recently, mammography have been the primary means of detecting early breast cancer. Although there is a risk of radiation- induced carcinogenesis associated with the x-ray examination of the female breast, but this risk is small compared to its benefits with modern equipment and technique. Therefore, it is important to determine the dose of the tissue at risk from radiation exposure by measuring the mean glandular dose (MGD). This can help minimize the risk to the patient. This paper describe the MGD measurement done on various types and thickness of breast phantom using a Bennett mammography machine model DMF-150 in the Medical Physics laboratory at the Malaysian Institute for Nuclear Technology Research (MINT). Results of this study are discussed in this paper. (Author)

Estimation of average glandular dose depending on the thickness of the breast; Estimativa da dose glandular media em funcao da espessura da mama

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Real, Jessica V.; Luz, Renata M. da, E-mail: jessica.real@pucrs.br, E-mail: renata.luz@pucrs.br [Hospital Sao Lucas (HSL/PUCRS), Porto Alegre, RS (Brazil); Fröhlich, Bruna D.; Pertile, Alessandra S.; Silva, Ana Maria Marques da, E-mail: bruna.frohlich@acad.pucrs.br, E-mail: lessandra.pertile@acad.pucrs.br, E-mail: ana.marques@pucrs.br [Pontificia Universidade Catolica do Rio Grande do Sul (PUCRS), Porto Alegre, RS (Brazil)

2014-07-01

Breast cancer is the most common type of cancer in women worldwide. Mammography is, to date, the most efficient method for detecting an abnormality in the patient's breast. It is a technique of imaging diagnostic that requires special care because radiographs without adequate quality may lead to a false diagnosis and lead to the need for a repeat examination, increasing the dose of radiation in the patient. This study aimed to evaluate the average glandular dose (AGD), depending on the breast thickness in patients undergoing routine tests, with a digital computer radiography processing system. Analyzed 30 exhibitions in patients aged (65 ± 12) years, in the right and left caudal skull projections, for breasts with thicknesses between 45 mm and 50 mm. The calculated value of the AGD for this track thickness was (1.600 ± 0.009) mGy. The performance of mammography quality control tests was satisfactory and the AGD values obtained for the chosen thickness range is acceptable, since the threshold achievable is 1.6 mGy and the acceptable is 2 mGy. In Brazil, it is only required the input dose calculation in skin for 45 mm breasts. However, the calculation of AGD is required for different thicknesses of the breast, to identify the best mammographic pattern aiming at better image quality at the lowest dose provided the patient.

Estimation of the average glandular dose on a team of tomosynthesis; Estimacion de la dosis glandular media en un equipo de tomosintesis

Energy Technology Data Exchange (ETDEWEB)

Nunez Martinez, L. M. R.; Sanchez Jimenez, J.; Pizarro trigo, F.

2013-07-01

Seeking to improve the information that gives us an image of mammography the manufacturers have implemented tomosynthesis. With this method of acquisition and reconstruction of image we went from having a 2D to a 3D image image, in such a way that it reduces or eliminates the effect of overlap of tissues. The estimate of the dose, which is always a fundamental parameter in the control of quality of radiology equipment, is more in the case of mammography by the radiosensitivity of this body and the frequency of their use. The objective of this work is the determination of the mean in a team glandular dose of with tomosynthesis mammography. (Author)

A study on the image quality of mammography and the average glandular dose

International Nuclear Information System (INIS)

Lee, In Ja; Kim, Hak Sung; Kim, Sung Soo; Huh, Joon

2002-01-01

We came to the following conclusion as the results of experiment on the image quality of mammography and the average glandular dose using 4 apparatuses at 3 hospital in Seoul. Whereas the measurement of half value layer showed no differences among the apparatuses, the measurement by an attenuation curve method showed some differences by 5.9%. There were 9.1% differences in the measurement by aluminum conversion method. The basic density of an automatic exposure control unit must be D = 1.40, but there was no automatic exposure unit adjusted precisely at any hospital. The unit at the B hospital exceeded the allowable limit by ± 0.15. In the photographing using an automatic exposure control unit and the management of an automatic film processor using a sensitometer, most automatic film processors were well kept. But in some cases the mean value of a fluctuation coefficient exceeded the allowable limit. There is a need for more cautious management. The image quality of breast phantom photography was affected by the screen/film system among the hospital. The average glandular dose at a breast of 4.2 cm thickness depended on the tube voltage, In the case of Mo/Mo, it was measured 0.26 ∼ 1.39 mGy less than ACR standard 3.0 mGy

Estimates of Average Glandular Dose with Auto-modes of X-ray Exposures in Digital Breast Tomosynthesis

Directory of Open Access Journals (Sweden)

Izdihar Kamal

2015-05-01

Full Text Available Objectives: The aim of this research was to examine the average glandular dose (AGD of radiation among different breast compositions of glandular and adipose tissue with auto-modes of exposure factor selection in digital breast tomosynthesis. Methods: This experimental study was carried out in the National Cancer Society, Kuala Lumpur, Malaysia, between February 2012 and February 2013 using a tomosynthesis digital mammography X-ray machine. The entrance surface air kerma and the half-value layer were determined using a 100H thermoluminescent dosimeter on 50% glandular and 50% adipose tissue (50/50 and 20% glandular and 80% adipose tissue (20/80 commercially available breast phantoms (Computerized Imaging Reference Systems, Inc., Norfolk, Virginia, USA with auto-time, auto-filter and auto-kilovolt modes. Results: The lowest AGD for the 20/80 phantom with auto-time was 2.28 milliGray (mGy for two dimension (2D and 2.48 mGy for three dimensional (3D images. The lowest AGD for the 50/50 phantom with auto-time was 0.97 mGy for 2D and 1.0 mGy for 3D. Conclusion: The AGD values for both phantoms were lower against a high kilovolt peak and the use of auto-filter mode was more practical for quick acquisition while limiting the probability of operator error.

Glandular dose and image quality control in mammography facilities with computerized radiography systems; Dose glandular e controle de qualidade da imagem em servicos de mamografia com sistema de radiografia computadorizada

Energy Technology Data Exchange (ETDEWEB)

Dantas, Marcelino Vicente de Almeida

2010-07-01

Breast cancer is the most common cancer among women, and early detection is critical to its diagnosis and treatment. To date, the most effective method for early detection of breast cancer has been x-ray mammography for which the screen/film (SF) technique has been the gold standard. However, even though SF combinations have been improved and optimized over the years for breast imaging, there are some critical limitations, including a narrow exposure range, image artifacts, film processing problems, and inflexibility in image processing and film management. In recent years, digital mammography has been introduced in cancer screening programmes with the screen/film techniques gradually being phased out. Computed radiography (CR), also commonly known as photostimulable phosphor (PSP) imaging or storage phosphor, employs reusable imaging plates and associated hardware and software to acquire and to display digital projection radiographs. In this work, a protocol model was tested for performing image quality control and average glandular dose (AGD) evaluation in 19 institutions with computed radiography systems for mammography. The protocol was validated through tests at the Laboratorio de Radioprotecao Aplicada a Mamografia (LARAM) from the Centro de Desenvolvimento da Tecnologia Nuclear (CDTN). The image quality visual evaluation of CDMAM phantom showed that 53% of the facilities were able to produce images of excellent quality. Furthermore, the automated evaluation of image quality, using the analyze software cdcom.exe, showed that 57% of the images were considered to be of good quality. The detector linearity test showed that the CR response is very linear, where 95% of facilities evaluated were considered to be compliant. For the image noise was found that only 20% of facilities are in agreement with the parameters established for this test. The average glandular doses, which patients may be getting to perform an examination, were below the action levels

A Stochastic Polygons Model for Glandular Structures in Colon Histology Images.

Science.gov (United States)

Sirinukunwattana, Korsuk; Snead, David R J; Rajpoot, Nasir M

2015-11-01

In this paper, we present a stochastic model for glandular structures in histology images of tissue slides stained with Hematoxylin and Eosin, choosing colon tissue as an example. The proposed Random Polygons Model (RPM) treats each glandular structure in an image as a polygon made of a random number of vertices, where the vertices represent approximate locations of epithelial nuclei. We formulate the RPM as a Bayesian inference problem by defining a prior for spatial connectivity and arrangement of neighboring epithelial nuclei and a likelihood for the presence of a glandular structure. The inference is made via a Reversible-Jump Markov chain Monte Carlo simulation. To the best of our knowledge, all existing published algorithms for gland segmentation are designed to mainly work on healthy samples, adenomas, and low grade adenocarcinomas. One of them has been demonstrated to work on intermediate grade adenocarcinomas at its best. Our experimental results show that the RPM yields favorable results, both quantitatively and qualitatively, for extraction of glandular structures in histology images of normal human colon tissues as well as benign and cancerous tissues, excluding undifferentiated carcinomas.

Glandular dose and image quality control in mammography facilities with computerized radiography systems

International Nuclear Information System (INIS)

Dantas, Marcelino Vicente de Almeida

2010-01-01

Breast cancer is the most common cancer among women, and early detection is critical to its diagnosis and treatment. To date, the most effective method for early detection of breast cancer has been x-ray mammography for which the screen/film (SF) technique has been the gold standard. However, even though SF combinations have been improved and optimized over the years for breast imaging, there are some critical limitations, including a narrow exposure range, image artifacts, film processing problems, and inflexibility in image processing and film management. In recent years, digital mammography has been introduced in cancer screening programmes with the screen/film techniques gradually being phased out. Computed radiography (CR), also commonly known as photostimulable phosphor (PSP) imaging or storage phosphor, employs reusable imaging plates and associated hardware and software to acquire and to display digital projection radiographs. In this work, a protocol model was tested for performing image quality control and average glandular dose (AGD) evaluation in 19 institutions with computed radiography systems for mammography. The protocol was validated through tests at the Laboratorio de Radioprotecao Aplicada a Mamografia (LARAM) from the Centro de Desenvolvimento da Tecnologia Nuclear (CDTN). The image quality visual evaluation of CDMAM phantom showed that 53% of the facilities were able to produce images of excellent quality. Furthermore, the automated evaluation of image quality, using the analyze software cdcom.exe, showed that 57% of the images were considered to be of good quality. The detector linearity test showed that the CR response is very linear, where 95% of facilities evaluated were considered to be compliant. For the image noise was found that only 20% of facilities are in agreement with the parameters established for this test. The average glandular doses, which patients may be getting to perform an examination, were below the action levels

Determination of mean glandular dose on patients and phantom in X-ray mammography

International Nuclear Information System (INIS)

Avramova-Cholakova, S.; Vassileva, J.

2008-01-01

The statistics of breast cancer rate in Bulgaria show a tendency towards increase of the morbidity from this disease. Last years campaigns against breast cancer are organized yearly. This leads to an increased number of screening and diagnostic mammograms that are made in the country. The dose associated with the examination is very low but not slightingly small. The glandular tissue in the breast is considered to be the most sensitive in relation to the radiation exposure. Several publications propose different methods, measurement set up or conversion coefficients for the calculation of the mean glandular dose (MGD) delivered to the breast during the X-ray examination. The question about the standardization of the measurement procedures arises since the differences in the results obtained using different methodologies may be quite big. The aim of this work is to develop a standard procedure for the measurement of MGD based on the recommendations mentioned in the European protocol on dosimetry in mammography, the European protocol for the quality control of the physical and technical aspects of mammography screening and the Code of practice: TRS 457 of the IAEA. Five contemporary film-screen mammography units were included in this study. Attention should be paid to the measurement set up. The reference point is chosen 6 cm from the chest wall edge laterally centered. If an ionization chamber is used for dose measurements the compression plate should be placed in close contact with it. If solid state detectors are used the compression plate should be put away from the detector and the output recalculated like if the plate is near the detector. The conversion coefficients for age dependence are not used in this study as not appropriate for the population included in it. PMMA measurements for the determination of diagnostic reference levels could be used but more correct results would be obtained with patient measurements

Assessment of mean glandular dose for patients in mammography in some Hospitals in Khartoum state

International Nuclear Information System (INIS)

Abu Elmola, Alaa Mahdi

2016-12-01

A mammography examination facilitates the early detection of breast cancer. However, the potential risk of radiation- induced carcinogenesis is also increased with such a procedure. Thus assessment of the breast dose is important. The objective of this study was to determine the mean glandular dose (MGD) resulting from cranio caudal(CC) and mediolateral oblique (MLO) views in one breast and the total dose per woman in Sudan, and to identify the factors affecting it. Measurements were performed to estimate mean glandular doses for 60 patients who underwent mammography examination in two clinics in Khartoum, Sudan.Doses were studied in RCH and NDC, centers which were using computed radiography(CR)devices. The piranha system was used for determining the MGD in this work. The characteristics of the radiographic equipment and the exposure data of each patient were recorded using designed format. The MGD was calculated from the measured incident Air kerma using appropriate conversion coefficients. The range of CBT was (1-7)cm for two projections. The respective averages for the CC and MLO projections were (4.55±1.38)mGy and (4.15±1.33) mGy, respectively. The average MGD per image was (4.3±1.35)mGy. The MGD per women was (8.6±1.35)mGy. The mean±SD MGD per image in the present study was lower than most of similar reports. The average MGD values recorded in this study were above the limiting value of the Institute of Physical Sciences in Medicine(2.0 mGy) and American College of Radiology (3.0 mGy recommendation. This suggests that mammography x-ray generators in this case are not capable of achieving acceptable dose levels for patients safety. Therefore, with consideration of all other factors, quality control program tests must be carried out periodically and frequently of the mammography equipment.(Author)

Guideline for determining the mean glandular dose according to DIN 6868-162 and threshold contrast visibility according to the quality assurance guideline for digital mammography systems.

Science.gov (United States)

Sommer, A; Schopphoven, S; Land, I; Blaser, D; Sobczak, T

2014-05-01

As part of the physico-technical quality assurance of the German breast cancer screening program, the threshold contrast visibility and the average glandular dose of every digital mammography system have to fulfill the requirements of the "European guidelines for quality assurance in breast cancer screening and diagnosis" (4th Edition). To accomplish uniform measurements in all federal states of Germany, the physical board of the reference centers developed a special guideline in 2009. Due to recent changes in the guidelines and standards, a second version of the guideline was developed by the reference centers. This guideline describes the determination of the average glandular dose as well as the CDMAM image acquisition and the CDMAM image evaluation. The determination of the threshold contrast visibility can be performed visually or automatically. The determination of the average glandular dose is based on DIN 6868 - 162 and the threshold contrast visibility test is based on the German "Quality Assurance Guideline". © Georg Thieme Verlag KG Stuttgart · New York.

SU-F-I-01: Normalized Mean Glandular Dose Values for Dedicated Breast CT Using Realistic Breast-Shaped Phantoms

Energy Technology Data Exchange (ETDEWEB)

Hernandez, A [Department of Radiology, Biomedical Engineering Graduate Group, University of California Davis, Sacramento, CA (United States); Boone, J [Departments of Radiology and Biomedical Engineering, Biomedical Engeering Graduate Group, University of California Davis, Sacramento, CA (United States)

2016-06-15

Purpose: To estimate normalized mean glandular dose values for dedicated breast CT (DgN-CT) using breast CT-derived phantoms and compare to estimations using cylindrical phantoms. Methods: Segmented breast CT (bCT) volume data sets (N=219) were used to measure effective diameter profiles and were grouped into quintiles by volume. The profiles were averaged within each quintile to represent the range of breast sizes found clinically. These profiles were then used to generate five voxelized computational phantoms (V1, V2, V3, V4, V5 for the small to large phantom sizes, respectively), and loaded into the MCNP6 lattice geometry to simulate normalized mean glandular dose coefficients (DgN-CT) using the system specifications of the Doheny-prototype bCT scanner in our laboratory. The DgN-CT coefficients derived from the bCT-derived breast-shaped phantoms were compared to those generated using a simpler cylindrical phantom using a constant volume, and the following constraints: (1) Length=1.5*radius; (2) radius determined at chest wall (Rcw), and (3) radius determined at the phantom center-of-mass (Rcm). Results: The change in Dg-NCT coefficients averaged across all phantom sizes, was - 0.5%, 19.8%, and 1.3%, for constraints 1–3, respectively. This suggests that the cylindrical assumption is a good approximation if the radius is taken at the breast center-of-mass, but using the radius at the chest wall results in an underestimation of the glandular dose. Conclusion: The DgN-CT coefficients for bCT-derived phantoms were compared against the assumption of a cylindrical phantom and proved to be essentially equivalent when the cylinder radius was set to r=1.5/L or Rcm. While this suggests that for dosimetry applications a patient’s breast can be approximated as a cylinder (if the correct radius is applied), this assumes a homogenous composition of breast tissue and the results may be different if the realistic heterogeneous distribution of glandular tissue is considered

Relationship of Compressed Breast Thickness and Average Glandular Dose According to Focus/Filter

International Nuclear Information System (INIS)

Lee, In Ja

2009-01-01

The study examined the relationship between the compressed breast thickness and Average Glandular Dose (AGD) among 1,969 outpatients who went through breast X-ray in a university hospital for 10 months from July 1st, 2007 to April 30th, 2008. Then it analyzed the result acquired from 3,900 cases of Cranio-Caudal (CC) view, especially, when the breasts were compressed (13-15daN). The following is the conclusion driven from the relationship analysis. 1. The subjects aged in 40s and 50s were 2,679 out of 3,900 cases and this figure was 68.69% in all. 2. In terms of distribution depending on focus/filter, 41.0% was Mo/Mo, 34.8% was Mo/Rh, and 24.2% was Rh/Rh. 3. In terms of compressed breast thickness depending on focus/filter, the average thickness was 26.91 mm at Mo/Mo, 38.84 mm at Mo/Rh, and 48.80 mm at Rh/Rh. The average thickness of the entire cases was shown to be 36.27 mm. 4. AGD depending on focus/filter was 1.27 mGy at Mo/Mo, 1.55 mGy at Mo/Rh, and 1.42 mGy at Rh/Rh. The average glandular dose of the entire cases was shown to be 1.43 mGy. 5. The relationship of AGD depending on compressed breast thickness at Mo/Mo was y=0.0318x + 0.470 while it was y=0.0206x + 0.709 at Mo/Rh and y=0.0248x + 0.335 at Mo/Rh. It was highly influenced by the compressed breast thickness, however, more variation was detected at Mo/Mo depending on breast thickness.

Estimation of average glandular dose depending on the thickness of the breast

International Nuclear Information System (INIS)

Real, Jessica V.; Luz, Renata M. da; Fröhlich, Bruna D.; Pertile, Alessandra S.; Silva, Ana Maria Marques da

2014-01-01

Breast cancer is the most common type of cancer in women worldwide. Mammography is, to date, the most efficient method for detecting an abnormality in the patient's breast. It is a technique of imaging diagnostic that requires special care because radiographs without adequate quality may lead to a false diagnosis and lead to the need for a repeat examination, increasing the dose of radiation in the patient. This study aimed to evaluate the average glandular dose (AGD), depending on the breast thickness in patients undergoing routine tests, with a digital computer radiography processing system. Analyzed 30 exhibitions in patients aged (65 ± 12) years, in the right and left caudal skull projections, for breasts with thicknesses between 45 mm and 50 mm. The calculated value of the AGD for this track thickness was (1.600 ± 0.009) mGy. The performance of mammography quality control tests was satisfactory and the AGD values obtained for the chosen thickness range is acceptable, since the threshold achievable is 1.6 mGy and the acceptable is 2 mGy. In Brazil, it is only required the input dose calculation in skin for 45 mm breasts. However, the calculation of AGD is required for different thicknesses of the breast, to identify the best mammographic pattern aiming at better image quality at the lowest dose provided the patient

Comparative evaluation of average glandular dose and image of digital mammography and film mammography in Minas Gerais, Brazil

International Nuclear Information System (INIS)

Nogueira, M.; Leyton, F.; Rodrigue, L. L.C.; Oliveira, M.A.; Joana, G.S.; Silva, S.D.

2015-01-01

Breast cancer is the most common cancer among women, and early detection is critical to its diagnosis and treatment. Mammography is the best method for breast-cancer screening and is capable of reducing mortality rates To date, the most effective method for early detection of breast cancer has been x-ray mammography for which the screen/film (SF) technique has been the gold standard. Digital mammography has been proposed as a substitute for film mammography given the benefits inherent to digital technology. The purpose of our study was to compare the technical performance of digital mammographic and screen-film mammography. A PMMA phantom with objects to simulate breast structures. For the screen/film (SF) technique the results showed that 54% mammography units did not achieve the minimum acceptable performance as far the image quality. Besides, 67% services showed inadequate performance in their processing systems, which had significant influence on the image quality. At the mean glandular dose only 44% of digital systems evaluated were compliant in all thicknesses of PMMA. The average glandular dose AGD was 90 % higher than in screen/film systems. (authors)

Estimation of mean glandular dose for patients who undergo mammography and studying the factors affecting it

Science.gov (United States)

Barzanje, Sana L. N. H.; Harki, Edrees M. Tahir Nury

2017-09-01

The objective of this study was to determine mean glandular dose (MGD) during diagnostic mammography. This study was done in two hospitals in Hawler city in Kurdistan -region /Iraq, the exposure parameters kVp and mAs was recorded for 40 patients under go mammography. The MGD estimated by multiplied ESD with normalized glandular dose (Dn). The ESD measured indirectly by measuring output radiation mGy/mAs by using PalmRAD 907 as a suitable detector (Gigger detector).the results; shown that the mean and its standard deviation of MGD for Screen Film Mammography and Digital Mammography are (0.95±0.18)mGy and (0.99±0.26)mGy, respectively. And there is a significant difference between MGD for Screen Film Mammography and Digital Mammography views (p≤0. 05). Also the mean value and its standard deviation of MGD for screen film mammography is (0.96±0.21) for CC projection and (1.03±0.3) mGy for MLO projection, but mean value and its standard deviation evaluated of MGD for digital mammography is (0.92±0.17) mGy for CC projection and (0.98±0.2) mGy for MLO projection. As well as, the effect of kVp and mAs in MGD were studied, shows that in general as kVp and mAs increased the MGD increased accordingly in both of mammography systems.

Immunohistochemical characterization of glandular elements in glandular cardiac myxoma: Study of six cases

Directory of Open Access Journals (Sweden)

Devajit Nath

2017-01-01

Full Text Available Back ground: Glandular cardiac myxoma has varying clinical presentation with uncertain histogenesis and debatable immunohistochemical profile. Glandular epithelial differentiations are rare phenomenon known to be present as an intrinsic component of the tumor. The origin of the glands has been attributed to epithelial differentiation of a totipotent cardiomyogenic precursor cells or the entrapped foregut rests in the tumor. Materials and Methods: Retrospective study includes six cases of glandular cardiac myxoma collected over a perior of 4 years. Sections were examined to define the histogenesis, histological and immunohistochemical profile of the glandular elements. Results: Incidence of glandular cardiac myxoma was 6.6% with a male to female ratio of 1:2.Mean age was 49.9 years. Left atrium was the commonest site. Five were sporadic and one was familial. Chest pain and dyspnea were the commonest clinical symptoms. Histologically all myxoma showed well formed glandular structures with typical myxomatous area. No atypia, mitosis or necrosis was identified in the glandular elements. Markers in six cases of glandular cardiac myxoma were immunopositive for CK7, CK 19, EMA, CEA, focally for E-cadherin while immunonegative for CK20, Chromogranin, Synaptophysin, calretenin, vimentin, B-catenin, TTF-1 and GCDFP-15 favoring enteric differentiation. Conclusion: Glandular cardiac myxoma is a rare entity which shows characteristics similar to those of classical cardiac myxoma with benign glandular elements showing enteric differentiation. Complete surgical excision is the treatment of choice with good prognosis. It is important to recognize this entity to avoid an erroneous diagnosis of metastatic adenocarcinoma.

Evaluation of the influence of parameters that determine the mean glandular dose in mammography using different detectors

International Nuclear Information System (INIS)

Costa, K.; Nogueira, M. S.

2015-10-01

Full text: Mammography is a test used for early detection of breast cancer. The mean glandular dose (MGD) is dosimetric greatness accepted as indicative of carcinogenic risk induced by ionizing radiation in the breasts of women undergoing mammography exams. MGD value is estimated from the incident air kerma (k i), associated with conversion factors which depend on the half-value layer (HVL), the breast composition and thickness compressed breast. This study aims to evaluate the influence of the parameters used to determine the MGD using different measurement detectors. Measurements were performed on a Siemens Mammomat Model 300 Nova mammography equipment; this has the combinations Anode/Filter of Mo/Mo, Mo/Rh and W/Rh. Detectors used were the ionization chamber Model 10X6-6M manufactured by Radcal Co., two solid-state detectors, one Model AGMS-M manufactured by Radcal Co. and other Model Xi Mammo manufactured by UNFORS. The detectors measures were compared and the MGD value was estimated; differences between measurements and the reference values were higher in HVL and k i parameters. The results are displayed according to other published works. (Author)

Plant Glandular Trichomes

Indian Academy of Sciences (India)

landing on the plant. Glandular trichomes in catmint (Nepeta sp.) produce nepetalactone, closely related to the aphid sex pheromone, nepetalactol. Nepetalactone can be reduced to the corresponding nepetalactol. ... Plant glandular trichomes function either as repositories or releasing sites of various chemicals. Interest in ...

Evaluation of mean glandular dose in a full-field digital mammography unit in Tabriz (IR)

International Nuclear Information System (INIS)

Riabi, H. A.; Mehnati, P.; Mesbahi, A.

2010-01-01

This study was aimed at evaluating the mean glandular dose (MGD) and affecting factors during mammography examinations by a full-field digital mammography unit. An extensive quality control program was performed to assure that the unit is properly working. Required information including compressed breast thickness (CBT), breast parenchymal pattern and technical factors used for imaging were recorded. An entrance skin exposure measurement was also performed using slabs of polymethylmethacrylate with 2-8 cm thickness. On the basis of recorded information and measured data, the MGD was estimated for 1145 mammography examinations obtained from 298 patients. Mean CBTs of 4.9 and 5.8 cm and MGDs of 2 and 2.4 mGy were observed for cranio-caudal and medio-lateral oblique views, respectively. Significant correlation was seen between MGD and CBT, breast parenchymal pattern and applied kVp and mAs. (authors)

Morphological differentiation of non-glandular and glandular trichomes on Marrubium vulgare L.

Directory of Open Access Journals (Sweden)

Marta Dmitruk

2014-04-01

Full Text Available Marrubium vulgare L., commonly known as a white horehound or common horehound, belongs to the plant family Lamiaceae. It is a perennial aromatic herb which grows naturally in Europe, Asia, and America. Since ancient Egypt, this species has been known as a remedy for upper respiratory tract ailments. Nowadays, horehound is used in herbal medicine for treatment of liver diseases, biliary tract disorders, and for increasing the appetite and supporting the function of the stomach. The main biologically active substances in M. vulgare organs are: marrubiin, tannins, essential oils, and ursolic acid. The paper presents micromorphological analyses of non-glandular and glandular trichomes of M. vulgare. The research material was sampled from the plant collection in the Botanical Garden of the Maria Curie-Sklodowska University in Lublin (51°14′ N, 22°34′ E. The above-ground parts of horehound were collected during the flowering period in July 2013. Using light microscopy (LM and scanning electron microscopy (SEM, the types and sizes of trichomes from the stem, leaf, calyx, and corolla were investigated. The results of the microscopic observations show that the surfaces of M. vulgare vegetative and reproductive organs are densely clothed with glandular and non-glandular trichomes. The glandular trichomes are of two main types: peltate and capitate. Peltate trichomes consist of a short stalk cell and a large head with secretory cells arranged in a circle. The height of a mature trichome is about 31.33 μm and the diameter of the head is 31.47 μm. The substance produced by secretory cells passes through the apical walls and accumulates within a space between the cuticle and the cell wall layer. Capitate long trichomes with a basal cell, long stalk, neck cell, and a unicellular head are 36.65 μm long and the diameter of the head is about 15.6 μm. There are two types of short capitate trichomes: with a bicellular head and a unicellular stalk and with

Evaluation of the influence of parameters that determine the mean glandular dose in mammography using different detectors; Evaluacion de la influencia de los parametros que determinan la dosis glandular media en Mamografia utilizando diferentes detectores

Energy Technology Data Exchange (ETDEWEB)

Costa, K.; Nogueira, M. S., E-mail: katicostabh@gmail.com [Centro de Desenvolvimento da Tecnologia Nuclear, Pos-graduacao em Ciencias e Tecnologia das Radiacoes, Minerais e Materiais / CNEN, Av. Pte. Antonio Carlos 6627, 31270-901 Belo Horizonte, Minas Gerais (Brazil)

2015-10-15

Full text: Mammography is a test used for early detection of breast cancer. The mean glandular dose (MGD) is dosimetric greatness accepted as indicative of carcinogenic risk induced by ionizing radiation in the breasts of women undergoing mammography exams. MGD value is estimated from the incident air kerma (k i), associated with conversion factors which depend on the half-value layer (HVL), the breast composition and thickness compressed breast. This study aims to evaluate the influence of the parameters used to determine the MGD using different measurement detectors. Measurements were performed on a Siemens Mammomat Model 300 Nova mammography equipment; this has the combinations Anode/Filter of Mo/Mo, Mo/Rh and W/Rh. Detectors used were the ionization chamber Model 10X6-6M manufactured by Radcal Co., two solid-state detectors, one Model AGMS-M manufactured by Radcal Co. and other Model Xi Mammo manufactured by UNFORS. The detectors measures were compared and the MGD value was estimated; differences between measurements and the reference values were higher in HVL and k i parameters. The results are displayed according to other published works. (Author)

Validation of mean glandular dose values provided by a digital breast tomosynthesis system in Brazil

International Nuclear Information System (INIS)

Beraldo O, B.; Paixao, L.; Donato da S, S.; Araujo T, M. H.; Nogueira, M. S.

2014-08-01

Digital breast tomosynthesis (DBT) is an emerging imaging modality that provides quasi-three-dimensional structural information of the breast and has strong promise to improve the differentiation of normal tissue and suspicious masses reducing the tissue overlaps. DBT images are reconstructed from a sequence of low-dose X-ray projections of the breast acquired at a small number of angles over a limited angular range. The Ho logic Selen ia Dimensions system is equipped with an amorphous Selenium (a-Se) detector layer of 250 μm thickness and a 70 μm pixel pitch. Studies are needed to determine the radiation dose of patients that are undergoing this emerging procedure to compare with the results obtained in DBT images. The mean glandular dose (D G ) is the dosimetric quantity used in quality control of the mammographic systems. The aim of this work is to validate D G values for different breast thicknesses provided by a Ho logic Selen ia Dimensions system using a DBT mode in comparison with the same results obtained by a calibrated 90 X 5-6M-model Radcal ionization chamber. D G values were derived from the incident air kerma (K i ) measurements and tabulated conversion coefficients that are dependent on the half value layer (HVL) of the X-ray spectrum. Voltage and tube loading values were recorded in irradiations using W/Al anode/filter combination, automatic exposure control mode and polymethyl methacrylate (PMMA) slabs which simulate different breast thicknesses. For K i measurements, the ionization chamber was positioned at 655 mm from the focus and the same radiographic technique values were selected with the manual mode. D G values for a complete procedure ranged from 0.9 ± 0.1 to 3.7 ± 0.4 mGy. The results for different breast thicknesses are in accordance with values obtained by DBT images and with acceptable levels established by the Commission of the European Communities (Cec) and the International Atomic Energy Agency (IAEA). This work contributes to

Validation of mean glandular dose values provided by a digital breast tomosynthesis system in Brazil

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Beraldo O, B.; Paixao, L.; Donato da S, S. [Centro de Desenvolvimento da Tecnologia Nuclear / CNEN, Post-graduation in Sciences and Technology of Radiations Minerals and Materials, Pte. Antonio Carlos 6627, 31270-901 Belo Horizonte (Brazil); Araujo T, M. H. [Dr Maria Helena Araujo Teixeira Clinic, Guajajaras 40, 30180-100 Belo Horizonte (Brazil); Nogueira, M. S., E-mail: bbo@cdtn.br [Centro de Desenvolvimento da Tecnologia Nuclear / CNEN, Pte. Antonio Carlos 6627, 31270-901 Belo Horizonte (Brazil)

2014-08-15

Digital breast tomosynthesis (DBT) is an emerging imaging modality that provides quasi-three-dimensional structural information of the breast and has strong promise to improve the differentiation of normal tissue and suspicious masses reducing the tissue overlaps. DBT images are reconstructed from a sequence of low-dose X-ray projections of the breast acquired at a small number of angles over a limited angular range. The Ho logic Selen ia Dimensions system is equipped with an amorphous Selenium (a-Se) detector layer of 250 μm thickness and a 70 μm pixel pitch. Studies are needed to determine the radiation dose of patients that are undergoing this emerging procedure to compare with the results obtained in DBT images. The mean glandular dose (D{sub G}) is the dosimetric quantity used in quality control of the mammographic systems. The aim of this work is to validate D{sub G} values for different breast thicknesses provided by a Ho logic Selen ia Dimensions system using a DBT mode in comparison with the same results obtained by a calibrated 90 X 5-6M-model Radcal ionization chamber. D{sub G} values were derived from the incident air kerma (K{sub i}) measurements and tabulated conversion coefficients that are dependent on the half value layer (HVL) of the X-ray spectrum. Voltage and tube loading values were recorded in irradiations using W/Al anode/filter combination, automatic exposure control mode and polymethyl methacrylate (PMMA) slabs which simulate different breast thicknesses. For K{sub i} measurements, the ionization chamber was positioned at 655 mm from the focus and the same radiographic technique values were selected with the manual mode. D{sub G} values for a complete procedure ranged from 0.9 ± 0.1 to 3.7 ± 0.4 mGy. The results for different breast thicknesses are in accordance with values obtained by DBT images and with acceptable levels established by the Commission of the European Communities (Cec) and the International Atomic Energy Agency (IAEA

Structure and distribution of glandular and non-glandular trichomes on above-ground organs in Inula helenium L. (Asteraceae

Directory of Open Access Journals (Sweden)

Aneta Sulborska

2014-01-01

Full Text Available Micromorphology and distribution of glandular and non-glandular trichomes on the above-ground organs of Inula helenium L. were investigated using light and scanning electron microscopy (SEM. Two types of biseriate glandular trichomes, i.e. sessile and stalk hairs, and non-glandular trichomes were recorded. Sessile glandular trichomes were found on all examined I. helenium organs (with their highest density on the abaxial surface of leaves and disk florets, and on stems, whereas stalk glandular trichomes were found on leaves and stems. Sessile trichomes were characterised by a slightly lower height (58–103 μm and width (32–35 μm than the stalk trichomes (62–111 μm x 31–36 μm. Glandular hairs were composed of 5–7 (sessile trichomes or 6–9 (stalk trichomes cell tiers. Apical trichome cell tiers exhibited features of secretory cells. Secretion was accumulated in subcuticular space, which expanded and ruptured at the top, and released its content. Histochemical assays showed the presence of lipids and polyphenols, whereas no starch was detected. Non-glandular trichomes were seen on involucral bracts, leaves and stems (more frequently on involucral bracts. Their structure comprised 2–9 cells; basal cells (1–6 were smaller and linearly arranged, while apical cells had a prozenchymatous shape. The apical cell was the longest and sharply pointed. Applied histochemical tests revealed orange-red (presence of lipids and brow colour (presence of polyphenols in the apical cells of the trichomes. This may suggest that beside their protective role, the trichomes may participate in secretion of secondary metabolites.

Image quality, threshold contrast and mean glandular dose in CR mammography

International Nuclear Information System (INIS)

Jakubiak, R R; Gamba, H R; Neves, E B; Peixoto, J E

2013-01-01

In many countries, computed radiography (CR) systems represent the majority of equipment used in digital mammography. This study presents a method for optimizing image quality and dose in CR mammography of patients with breast thicknesses between 45 and 75 mm. Initially, clinical images of 67 patients (group 1) were analyzed by three experienced radiologists, reporting about anatomical structures, noise and contrast in low and high pixel value areas, and image sharpness and contrast. Exposure parameters (kV, mAs and target/filter combination) used in the examinations of these patients were reproduced to determine the contrast-to-noise ratio (CNR) and mean glandular dose (MGD). The parameters were also used to radiograph a CDMAM (version 3.4) phantom (Artinis Medical Systems, The Netherlands) for image threshold contrast evaluation. After that, different breast thicknesses were simulated with polymethylmethacrylate layers and various sets of exposure parameters were used in order to determine optimal radiographic parameters. For each simulated breast thickness, optimal beam quality was defined as giving a target CNR to reach the threshold contrast of CDMAM images for acceptable MGD. These results were used for adjustments in the automatic exposure control (AEC) by the maintenance team. Using optimized exposure parameters, clinical images of 63 patients (group 2) were evaluated as described above. Threshold contrast, CNR and MGD for such exposure parameters were also determined. Results showed that the proposed optimization method was effective for all breast thicknesses studied in phantoms. The best result was found for breasts of 75 mm. While in group 1 there was no detection of the 0.1 mm critical diameter detail with threshold contrast below 23%, after the optimization, detection occurred in 47.6% of the images. There was also an average MGD reduction of 7.5%. The clinical image quality criteria were attended in 91.7% for all breast thicknesses evaluated in both

Comparison of anode/filter combinations in digital mammography with respect to the average glandular dose

International Nuclear Information System (INIS)

Uhlenbrock, D.F.; Mertelmeier, Thomas

2009-01-01

To investigate the average glandular dose (AGD) applied for clinical digital mammograms acquired with the anode/filter combinations molybdenum/molybdenum (Mo/Mo), molybdenum/rhodium (Mo/Rh), and tungsten/rhodium (W/Rh). Using the method of Dance, the AGD was evaluated from the exposure data of 4867 digital mammograms at two sites equipped with a full-field digital mammography (FFDM) system based on an amorphous selenium detector. 1793 images were acquired and analyzed with Mo/Mo, 643 with Mo/Rh, and 2431 with W/Rh. In the Mo/Mo cases the mean compressed breast thickness was 46 ± 10 mm with an average AGD of 2.29 ± 1.31 mGy. For the Mo/Rh cases with a mean compressed thickness of 64 ± 9 mm, we obtained 2.76 ± 1.31 mGy. The W/Rh cases with a mean compressed thickness of 52 ± 13 mm resulted in 1.26 ± 0.44 mGy. The image quality was assessed as normal and adequate for diagnostic purposes in all cases. (orig.)

Monte Carlo simulations to assess the effects of tube current modulation on breast dose for multidetector CT

International Nuclear Information System (INIS)

Angel, Erin; Yaghmai, Nazanin; Jude, Cecilia Matilda; DeMarco, John J; Cagnon, Christopher H; Goldin, Jonathan G; McNitt-Gray, Michael F; Primak, Andrew N; McCollough, Cynthia H; Stevens, Donna M; Cody, Dianna D

2009-01-01

Tube current modulation was designed to reduce radiation dose in CT imaging while maintaining overall image quality. This study aims to develop a method for evaluating the effects of tube current modulation (TCM) on organ dose in CT exams of actual patient anatomy. This method was validated by simulating a TCM and a fixed tube current chest CT exam on 30 voxelized patient models and estimating the radiation dose to each patient's glandular breast tissue. This new method for estimating organ dose was compared with other conventional estimates of dose reduction. Thirty detailed voxelized models of patient anatomy were created based on image data from female patients who had previously undergone clinically indicated CT scans including the chest area. As an indicator of patient size, the perimeter of the patient was measured on the image containing at least one nipple using a semi-automated technique. The breasts were contoured on each image set by a radiologist and glandular tissue was semi-automatically segmented from this region. Previously validated Monte Carlo models of two multidetector CT scanners were used, taking into account details about the source spectra, filtration, collimation and geometry of the scanner. TCM data were obtained from each patient's clinical scan and factored into the model to simulate the effects of TCM. For each patient model, two exams were simulated: a fixed tube current chest CT and a tube current modulated chest CT. X-ray photons were transported through the anatomy of the voxelized patient models, and radiation dose was tallied in the glandular breast tissue. The resulting doses from the tube current modulated simulations were compared to the results obtained from simulations performed using a fixed mA value. The average radiation dose to the glandular breast tissue from a fixed tube current scan across all patient models was 19 mGy. The average reduction in breast dose using the tube current modulated scan was 17%. Results were

Dedicated breast CT: radiation dose for circle-plus-line trajectory

International Nuclear Information System (INIS)

Vedantham, Srinivasan; Shi, Linxi; Karellas, Andrew; Noo, Frederic

2012-01-01

Purpose: Dedicated breast CT prototypes used in clinical investigations utilize single circular source trajectory and cone-beam geometry with flat-panel detectors that do not satisfy data-sufficiency conditions and could lead to cone beam artifacts. Hence, this work investigated the glandular dose characteristics of a circle-plus-line trajectory that fulfills data-sufficiency conditions for image reconstruction in dedicated breast CT. Methods: Monte Carlo-based computer simulations were performed using the GEANT4 toolkit and was validated with previously reported normalized glandular dose coefficients for one prototype breast CT system. Upon validation, Monte Carlo simulations were performed to determine the normalized glandular dose coefficients as a function of x-ray source position along the line scan. The source-to-axis of rotation distance and the source-to-detector distance were maintained constant at 65 and 100 cm, respectively, in all simulations. The ratio of the normalized glandular dose coefficient at each source position along the line scan to that for the circular scan, defined as relative normalized glandular dose coefficient (RD g N), was studied by varying the diameter of the breast at the chest wall, chest-wall to nipple distance, skin thickness, x-ray beam energy, and glandular fraction of the breast. Results: The RD g N metric when stated as a function of source position along the line scan, relative to the maximum length of line scan needed for data sufficiency, was found to be minimally dependent on breast diameter, chest-wall to nipple distance, skin thickness, glandular fraction, and x-ray photon energy. This observation facilitates easy estimation of the average glandular dose of the line scan. Polynomial fit equations for computing the RD g N and hence the average glandular dose are provided. Conclusions: For a breast CT system that acquires 300-500 projections over 2π for the circular scan, the addition of a line trajectory with equal

Enhancement of lymphocyte proliferation by mouse glandular kallikrein.

Science.gov (United States)

Hu, Z Q; Murakami, K; Ikigai, H; Shimamura, T

1992-03-01

Mouse glandular kallikrein (mGK) strongly enhanced the spontaneous and mitogen-induced proliferation of lymphocytes. Both blast formation and 3H-TdR incorporation were dose-dependently enhanced at the same time many cells were killed. The enhancing activity was independent of EGF, because EGF-binding proteins (mGK-9 in mGK-6,9 mixture and mGK-13), renal kallikrein (mGK-6) and human kallikrein all displayed the same enhancement. A serine proteinase inhibitor, diisopropyl fluorophosphate, could block the enhancement by mGK. The new function suggests that mGK is important in the immune system as a regulatory molecule.

Average glandular dose in paired digital mammography and digital breast tomosynthesis acquisitions in a population based screening program: effects of measuring breast density, air kerma and beam quality

Science.gov (United States)

Helge Østerås, Bjørn; Skaane, Per; Gullien, Randi; Catrine Trægde Martinsen, Anne

2018-02-01

The main purpose was to compare average glandular dose (AGD) for same-compression digital mammography (DM) and digital breast tomosynthesis (DBT) acquisitions in a population based screening program, with and without breast density stratification, as determined by automatically calculated breast density (Quantra™). Secondary, to compare AGD estimates based on measured breast density, air kerma and half value layer (HVL) to DICOM metadata based estimates. AGD was estimated for 3819 women participating in the screening trial. All received craniocaudal and mediolateral oblique views of each breasts with paired DM and DBT acquisitions. Exposure parameters were extracted from DICOM metadata. Air kerma and HVL were measured for all beam qualities used to acquire the mammograms. Volumetric breast density was estimated using Quantra™. AGD was estimated using the Dance model. AGD reported directly from the DICOM metadata was also assessed. Mean AGD was 1.74 and 2.10 mGy for DM and DBT, respectively. Mean DBT/DM AGD ratio was 1.24. For fatty breasts: mean AGD was 1.74 and 2.27 mGy for DM and DBT, respectively. For dense breasts: mean AGD was 1.73 and 1.79 mGy, for DM and DBT, respectively. For breasts of similar thickness, dense breasts had higher AGD for DM and similar AGD for DBT. The DBT/DM dose ratio was substantially lower for dense compared to fatty breasts (1.08 versus 1.33). The average c-factor was 1.16. Using previously published polynomials to estimate glandularity from thickness underestimated the c-factor by 5.9% on average. Mean AGD error between estimates based on measurements (air kerma and HVL) versus DICOM header data was 3.8%, but for one mammography unit as high as 7.9%. Mean error of using the AGD value reported in the DICOM header was 10.7 and 13.3%, respectively. Thus, measurement of breast density, radiation dose and beam quality can substantially affect AGD estimates.

Average glandular dose in digital mammography and digital breast tomosynthesis: comparison of phantom and patient data

International Nuclear Information System (INIS)

Bouwman, R W; Van Engen, R E; Den Heeten, G J; Broeders, M J M; Veldkamp, W J H; Young, K C; Dance, D R; Schopphoven, S; Jeukens, C R L P N

2015-01-01

For the evaluation of the average glandular dose (AGD) in digital mammography (DM) and digital breast tomosynthesis (DBT) phantoms simulating standard model breasts are used. These phantoms consist of slabs of polymethyl methacrylate (PMMA) or a combination of PMMA and polyethylene (PE). In the last decades the automatic exposure control (AEC) increased in complexity and became more sensitive to (local) differences in breast composition. The question is how well the AGD estimated using these simple dosimetry phantoms agrees with the average patient AGD. In this study the AGDs for both dosimetry phantoms and for patients have been evaluated for 5 different x-ray systems in DM and DBT modes. It was found that the ratios between patient and phantom AGD did not differ considerably using both dosimetry phantoms. These ratios averaged over all breast thicknesses were 1.14 and 1.15 for the PMMA and PMMA-PE dosimetry phantoms respectively in DM mode and 1.00 and 1.02 in the DBT mode. These ratios were deemed to be sufficiently close to unity to be suitable for dosimetry evaluation in quality control procedures. However care should be taken when comparing systems for DM and DBT since depending on the AEC operation, ratios for particular breast thicknesses may differ substantially (0.83–1.96). Although the predictions of both phantoms are similar we advise the use of PMMA  +  PE slabs for both DM and DBT to harmonize dosimetry protocols and avoid any potential issues with the use of spacers with the PMMA phantoms. (paper)

Estimation of glandular content rate and statistical analysis of the influence of age group and compressed breast thickness on the estimated value

International Nuclear Information System (INIS)

Ohmori, Naoki; Ashida, Kenji; Fujita, Osamu

2003-01-01

Because the glandular content rate is an important factor in evaluating breast cancer detection and average glandular dose, it is important in mammography research to estimate and analyze this rate. The purpose of this study was to obtain a formula for statistical estimation of the glandular content rate, to clarify statistically the influence of age group and compressed breast thickness (CBT) on estimating the glandular content rate, and to show statistically the general relation between glandular content rate and the factors of age and CBT. The subjects were 740 Japanese women aged 20-91 years (mean±SD: 48.3±12.8 years) who had undergone mammography. In our study, the glandular content rate was statistically estimated from age group, mAs-value, and CBT when subjects underwent mammography, from a phantom simulation, and from MR images of the breast. In addition, multivariate analysis was carried to examine statistically the influence of age group and CBT on glandular content rate. The mean glandular content rate as estimated by age group was as follows: 35.6% for those in their 20s, 33.4% in the 30s, 27.5% in the 40s, 23.8% in the 50s, and 21.8% in those 60 and over. The rate for the subjects as a whole was 27.1%. This study indicated that overestimation occurred if the estimated value of the glandular content rate was not corrected in the 3D-measurement by MRI. In addition, this study showed that the statistical influence on glandular content rate was significantly larger for CBT than age. (author)

TU-F-18C-05: Evaluation of a Method to Calculate Patient-Oriented MGD Coefficients Using Estimates of Glandular Tissue Distribution

International Nuclear Information System (INIS)

Porras-Chaverri, M; Galavis, P; Bakic, P; Vetter, J

2014-01-01

Purpose: Evaluate mammographic mean glandular dose (MGD) coefficients for particular known tissue distributions using a novel formalism that incorporates the effect of the heterogeneous glandular tissue distribution, by comparing them with MGD coefficients derived from the corresponding anthropomorphic computer breast phantom. Methods: MGD coefficients were obtained using MCNP5 simulations with the currently used homogeneous assumption and the heterogeneously-layered breast (HLB) geometry and compared against those from the computer phantom (ground truth). The tissue distribution for the HLB geometry was estimated using glandularity map image pairs corrected for the presence of non-glandular fibrous tissue. Heterogeneity of tissue distribution was quantified using the glandular tissue distribution index, Idist. The phantom had 5 cm compressed breast thickness (MLO and CC views) and 29% whole breast glandular percentage. Results: Differences as high as 116% were found between the MGD coefficients with the homogeneous breast core assumption and those from the corresponding ground truth. Higher differences were found for cases with more heterogeneous distribution of glandular tissue. The Idist for all cases was in the [−0.8 − +0.3] range. The use of the methods presented in this work results in better agreement with ground truth with an improvement as high as 105 pp. The decrease in difference across all phantom cases was in the [9 − 105] pp range, dependent on the distribution of glandular tissue and was larger for the cases with the highest Idist values. Conclusion: Our results suggest that the use of corrected glandularity image pairs, as well as the HLB geometry, improves the estimates of MGD conversion coefficients by accounting for the distribution of glandular tissue within the breast. The accuracy of this approach with respect to ground truth is highly dependent on the particular glandular tissue distribution studied. Predrag Bakic discloses current

Results of a 2011 national questionnaire for investigation of mean glandular dose from mammography in Japan.

Science.gov (United States)

Asada, Y; Suzuki, S; Minami, K; Shirakawa, S

2014-03-01

Diagnostic reference levels (DRLs) for mammography have yet to be created in Japan. A national questionnaire investigation into radiographic conditions in Japan was carried out for the purpose of creating DRLs. Items investigated included the following: tube voltage; tube current; current-time product; source-image distance; craniocaudal view; automatic exposure control (AEC) settings; name of mammography unit; image receptor system (computed radiography (CR), flat panel detector (FPD), or film/screen (F/S)); and supported or unsupported monitor diagnosis (including monitor resolution). Estimation of the mean glandular dose (MGD) for mammography was performed and compared with previous investigations. The MGD was 1.58(0.48) mGy, which did not significantly differ from a 2007 investigation. In relation to image receptors, although no difference in average MGD values was observed between CR and FPD systems, F/S systems had a significantly decreased value compared to both CR and FPDs. Concerning digital systems (FPDs), the MGD value of the direct conversion system was significantly higher than the indirect conversion system. No significant difference in MGD value was evident concerning type of monitor diagnosis for either the CR or the FPD digital systems; however, hard copies were used more often in CR. No significant difference in the MGD value was found in relation to monitor resolution. This report suggests ways to lower the doses patients undergoing mammography receive in Japan, and serves as reference data for 4.2 cm compressed breast tissue of 50% composition DRLs. Furthermore, our findings suggest that further optimisation of FPD settings can promote a reduction in the MGD value.

PTEN phosphatase-independent maintenance of glandular morphology in a predictive colorectal cancer model system.

Science.gov (United States)

Jagan, Ishaan C; Deevi, Ravi K; Fatehullah, Aliya; Topley, Rebecca; Eves, Joshua; Stevenson, Michael; Loughrey, Maurice; Arthur, Kenneth; Campbell, Frederick Charles

2013-11-01

Organotypic models may provide mechanistic insight into colorectal cancer (CRC) morphology. Three-dimensional (3D) colorectal gland formation is regulated by phosphatase and tensin homologue deleted on chromosome 10 (PTEN) coupling of cell division cycle 42 (cdc42) to atypical protein kinase C (aPKC). This study investigated PTEN phosphatase-dependent and phosphatase-independent morphogenic functions in 3D models and assessed translational relevance in human studies. Isogenic PTEN-expressing or PTEN-deficient 3D colorectal cultures were used. In translational studies, apical aPKC activity readout was assessed against apical membrane (AM) orientation and gland morphology in 3D models and human CRC. We found that catalytically active or inactive PTEN constructs containing an intact C2 domain enhanced cdc42 activity, whereas mutants of the C2 domain calcium binding region 3 membrane-binding loop (M-CBR3) were ineffective. The isolated PTEN C2 domain (C2) accumulated in membrane fractions, but C2 M-CBR3 remained in cytosol. Transfection of C2 but not C2 M-CBR3 rescued defective AM orientation and 3D morphogenesis of PTEN-deficient Caco-2 cultures. The signal intensity of apical phospho-aPKC correlated with that of Na(+)/H(+) exchanger regulatory factor-1 (NHERF-1) in the 3D model. Apical NHERF-1 intensity thus provided readout of apical aPKC activity and associated with glandular morphology in the model system and human colon. Low apical NHERF-1 intensity in CRC associated with disruption of glandular architecture, high cancer grade, and metastatic dissemination. We conclude that the membrane-binding function of the catalytically inert PTEN C2 domain influences cdc42/aPKC-dependent AM dynamics and gland formation in a highly relevant 3D CRC morphogenesis model system.

PTEN Phosphatase-Independent Maintenance of Glandular Morphology in a Predictive Colorectal Cancer Model System

Directory of Open Access Journals (Sweden)

Ishaan C. Jagan

2013-11-01

Full Text Available Organotypic models may provide mechanistic insight into colorectal cancer (CRC morphology. Three-dimensional (3D colorectal gland formation is regulated by phosphatase and tensin homologue deleted on chromosome 10 (PTEN coupling of cell division cycle 42 (cdc42 to atypical protein kinase C (aPKC. This study investigated PTEN phosphatase-dependent and phosphatase-independent morphogenic functions in 3D models and assessed translational relevance in human studies. Isogenic PTEN-expressing or PTEN-deficient 3D colorectal cultures were used. In translational studies, apical aPKC activity readout was assessed against apical membrane (AM orientation and gland morphology in 3D models and human CRC. We found that catalytically active or inactive PTEN constructs containing an intact C2 domain enhanced cdc42 activity, whereas mutants of the C2 domain calcium binding region 3 membrane-binding loop (M-CBR3 were ineffective. The isolated PTEN C2 domain (C2 accumulated in membrane fractions, but C2 M-CBR3 remained in cytosol. Transfection of C2 but not C2 M-CBR3 rescued defective AM orientation and 3D morphogenesis of PTEN-deficient Caco-2 cultures. The signal intensity of apical phospho-aPKC correlated with that of Na+/H+ exchanger regulatory factor-1 (NHERF-1 in the 3D model. Apical NHERF-1 intensity thus provided readout of apical aPKC activity and associated with glandular morphology in the model system and human colon. Low apical NHERF-1 intensity in CRC associated with disruption of glandular architecture, high cancer grade, and metastatic dissemination. We conclude that the membrane-binding function of the catalytically inert PTEN C2 domain influences cdc42/aPKC-dependent AM dynamics and gland formation in a highly relevant 3D CRC morphogenesis model system.

Breast Glandularity in Malaysian Women from a Full-Field Digital Mammography System

International Nuclear Information System (INIS)

Noriah Jamal; Humairah Samad Cheung; Siti Selina Abdul Hamid; Juliana Mahamad Napiah

2014-01-01

This study is undertaken to estimate breast glandularity in Malaysian women from a Full-Field Digital mammography System. This study involved 223 women (Malay=100;Chinese=101 and Indian=22) underwent voluntary screening mammography at Breast Centre, International Islamic University Malaysia (IIUM Breast Centre) for the first quarter of year 2009. Those are women aged between 31 to 69 years old (median age, 49 years). Data on miliampere-seconds, kilo voltage and compressed breast thickness for each cranio caudal view are used to estimate breast glandularity for an individual breast. Breast glandularity is calculated using the fitted equation reported earlier. The difference in breast glandularity among ethnic groups was tested for significance using the nonparametric Kruskal-Wallis test. The average breast glandularity estimated in our study, using FFDM system is 52.94±27.63 %. No significant difference was seen in breast glandularity among the ethnic groups (p>0.05, Kruskan Wallis test). Breast glandularity decrease as age increases, up to 60 years old. (author)

Automated Breast Density Computation in Digital Mammography and Digital Breast Tomosynthesis: Influence on Mean Glandular Dose and BIRADS Density Categorization.

Science.gov (United States)

Castillo-García, Maria; Chevalier, Margarita; Garayoa, Julia; Rodriguez-Ruiz, Alejandro; García-Pinto, Diego; Valverde, Julio

2017-07-01

The study aimed to compare the breast density estimates from two algorithms on full-field digital mammography (FFDM) and digital breast tomosynthesis (DBT) and to analyze the clinical implications. We selected 561 FFDM and DBT examinations from patients without breast pathologies. Two versions of a commercial software (Quantra 2D and Quantra 3D) calculated the volumetric breast density automatically in FFDM and DBT, respectively. Other parameters such as area breast density and total breast volume were evaluated. We compared the results from both algorithms using the Mann-Whitney U non-parametric test and the Spearman's rank coefficient for data correlation analysis. Mean glandular dose (MGD) was calculated following the methodology proposed by Dance et al. Measurements with both algorithms are well correlated (r ≥ 0.77). However, there are statistically significant differences between the medians (P density median values from FFDM are, respectively, 8% and 77% higher than DBT estimations. Both algorithms classify 35% and 55% of breasts into BIRADS (Breast Imaging-Reporting and Data System) b and c categories, respectively. There are no significant differences between the MGD calculated using the breast density from each algorithm. DBT delivers higher MGD than FFDM, with a lower difference (5%) for breasts in the BIRADS d category. MGD is, on average, 6% higher than values obtained with the breast glandularity proposed by Dance et al. Breast density measurements from both algorithms lead to equivalent BIRADS classification and MGD values, hence showing no difference in clinical outcomes. The median MGD values of FFDM and DBT examinations are similar for dense breasts (BIRADS d category). Published by Elsevier Inc.

A comparison of mean glandular dose diagnostic reference levels within the all-digital irish national breast screening programme and the Irish symptomatic breast services

International Nuclear Information System (INIS)

O'Leary, D.; Rainford, L.

2013-01-01

Data on image quality, compression and radiation dose were collected from symptomatic breast units within the Republic of Ireland. Quantitative and qualitative data were analysed using SPSS. Recommendations of mean glandular dose (MGD) diagnostic reference levels were made at various levels for film-screen and full field digital mammography units to match levels published worldwide. MGDs received by symptomatic breast patients within Ireland are higher than those received in the all-digital Irish Breast Screening service; 55-65 mm breast: 1.75 mGy (screening) vs. 2.4 mGy (symptomatic) at the 95. percentile; various reasons are proposed for the differences. MGDs achieved in the screening service may be lower because of the exacting requirements for radiographer training, characteristics of the patients and equipment quality assurance levels. More precise imaging guidelines, standards and training of symptomatic radiographers performing mammography are suggested to remediate MGDs delivered to the breasts of Irish women attending the symptomatic breast services. (authors)

Telomerase reverse transcriptase promoter mutations in glandular lesions of the urinary bladder.

Science.gov (United States)

Vail, Eric; Zheng, Xiaoyong; Zhou, Ming; Yang, Ximing; Fallon, John T; Epstein, Jonathan I; Zhong, Minghao

2015-10-01

Glandular lesions of the urinary bladder include a broad spectrum of entities ranging from completely benign to primary and secondary malignancies. The accurate diagnosis of these lesions is both important and challenging. Recently, studies suggest that telomerase reverse transcriptase (TERT) promoter mutations could be a biomarker for urothelial carcinoma (UC). We hypothesized that these mutations can distinguish UC with glandular differentiation from nephrogenic adenoma, primary adenocarcinoma of the urinary bladder (PAUB), or secondary malignancies. Twenty-five cases of benign glandular lesions (including nephrogenic adenoma); 29 cases of UC with glandular differentiation; 10 cases of PAUB; and 10 cases each of metastatic colon cancer, prostatic carcinoma, and carcinoma from Mullerian origin were collected. Slides were reviewed and selected to make sure the lesion was at least 10% to 20% of all tissue. Macrodissection was performed in some of cases, and genomic DNA was extracted from the tissue. Telomerase reverse transcriptase promoter mutations were determined by standard polymerase chain reaction sequencing. Twenty-one cases (72%) of UC with glandular differentiation were positive for TERT promoter mutations. However, none of the remaining cases (total 65 cases of benign lesions, PAUB, and metastatic carcinomas) was positive for TERT promoter mutation. Telomerase reverse transcriptase promoter mutations were highly associated with UC including UC with glandular differentiation but not other glandular lesions of bladder. Therefore, in conjunction with morphologic features, Immunohistochemistry stain profile, and clinical information, TERT promoter mutations could distinguish UC with glandular differentiation from other bladder glandular lesions. In addition, lack of TERT promoter mutations in primary adenocarcinoma of bladder suggests that this entity may have different origin or carcinogenesis from those of UC. Published by Elsevier Inc.

Phantoms for quality control procedures in digital breast tomosynthesis: dose assessment

NARCIS (Netherlands)

Bouwman, R. W.; Diaz, O.; van Engen, R. E.; Young, K. C.; den Heeten, G. J.; Broeders, M. J. M.; Veldkamp, W. J. H.; Dance, D. R.

2013-01-01

The recent introduction of digital breast tomosynthesis into clinical practice requires quality control procedures. In this study we have investigated whether the assessment of the average glandular dose for modelled standard breasts can be performed using a combination of polymethyl methacrylate

Structure and histochemistry of the glandular trichomes on the ...

African Journals Online (AJOL)

The glandular trichomes were classified into two subpopulations, namely the peltate and capitate glandular trichomes. The former was characterized by a short stalk and a large four-celled secretory head, while the latter was further subdivided into two groups; one has a short unicellular stalk and two-cellular head (type I), ...

Measurement of the radiation dose and assessment of the risk in mammography screening for early detection of cancer of the breast, in Israel

International Nuclear Information System (INIS)

Broisman, A.; Schlesinger, T.; Alfassi, Z. B.

2011-01-01

The mean glandular doses to samples of women attending for mammographic screening are measured routinely at screening centres in Israel. As at present, no detailed and systematic data have been collected regarding the average glandular dose in mammography screening procedures carried out in Israel for the last 20 y. Especially data are lacking related to the glandular dose (GD) involved in mammography with the new digital mammography systems. In this work, partial results of the measurements are presented to asses the radiation dose to the breast and to the glandular tissue within the Israeli national mammography programme updated to year 2009. (authors)

Evaluation of absorbed radiation dose in mammography using Monte Carlo simulation; Avaliacao da dose absorvida em mamografia usando simulacao Monte Carlo

Energy Technology Data Exchange (ETDEWEB)

Rodrigues, Bruno L.; Tomal, Alessandra [Universidade Estadual de Campinas (UNICAMP), Campinas, SP (Brazil). Instituto de Fisica Gleb Wataghin

2016-07-01

Mammography is the main tool for breast cancer diagnosis, and it is based on the use of X-rays to obtain images. However, the glandular tissue present within the breast is highly sensitive to ionizing radiation, and therefore requires strict quality control in order to minimize the absorbed dose. The quantification of the absorbed dose in the breast tissue can be done by using Monte Carlo simulation, which allows a detailed study of the deposition of energy in different regions of the breast. Besides, the results obtained from the simulation can be associated with experimental data and provide values of dose interest, such as the dose deposited in glandular tissue. (author)

Glandular Trichomes and Essential Oil of Thymus quinquecostatus

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Ping Jia

2013-01-01

Full Text Available The distribution and types of glandular trichomes and essential oil chemistry of Thymus quinquecostatus were studied. The glandular trichomes are distributed on the surface of stem, leaf, rachis, calyx and corolla, except petiole, pistil and stamen. Three morphologically distinct types of glandular trichomes are described. Peltate trichomes, consisting of a basal cell, a stalk cell and a 12-celled head, are distributed on the stem, leaf, corolla and outer side of calyx. Capitate trichomes, consisting of a unicellular base, a 1–2-celled stalk and a unicellular head, are distributed more diffusely than peltate ones, existing on stem, leaf, rachis and calyx. Digitiform trichomes are just distributed on the outer side of corolla, consisting of 1 basal cell, 3 stalk cells and 1 head cell. All three types of glandular trichomes can secrete essential oil, and in small capitate trichomes of rachis, all peltate trichomes and digitiform trichomes, essential oil is stored in a large subcuticular space, released by cuticle rupture, whereas, in other capitate trichomes, essential oil crosses the thin cuticle. The essential oil of T. quinquecostatus is yellow, and its content is highest in the growth period. 68 constituents were identified in the essential oils. The main constituent is linalool.

Dose absorbed in adults and children thyroid due to the I123 using the dosimetry MIRD and Marinelli

International Nuclear Information System (INIS)

Vasquez, M.; Castillo, C.; Cabrera, C.; Sarachaga, R.; Castaneda, J.; Diaz, E.

2014-08-01

Using the dosimetry MIRD, and representation Cristy-Eckerman in the thyroid gland and organs of their bio-kinetics when I 123 (Iodine) is used, the study demonstrates that the absorbed dose by the gland of an adult, children, and newly born, is their auto-dose, independent of the compartments number of their bio-kinetics. The dosimetric contributions of the organs of their bio-kinetics are insignificant. Their results are not significantly different to those obtained by the formalism MARINELLI (auto-dose) when it uses a sphere like glandular representation. In consequence, the kinetic model corresponding to the glandular representation decreases to a compartment, where the gland can also be represented like a sphere. (Author)

Higher glandular trichome density in tomato leaflets and repellence to spider mites Alta densidade de tricomas glandulares em tomateiro e aumento da repelência a ácaros rajados

Directory of Open Access Journals (Sweden)

Wilson Roberto Maluf

2007-09-01

Full Text Available The objective of this work was to evaluate the feasibility of selection for higher glandular trichome densities, as an indirect criterion of selection for increasing repellence to spider mites Tetranychus urticae, in tomato populations derived from an interspecific cross between Lycopersicon esculentum x L. hirsutum var. glabratum PI 134417. Trichome densities were evaluated in 19 genotypes, including 12 from advanced backcross populations, derived from the original cross L. esculentum x L. hirsutum var. glabratum PI 134417. Counts were made both on the adaxial and abaxial leaf surfaces, and trichomes were classified into glandular types IV and VI, other glandular types (types I+VII, and nonglandular types. Mite repellence was measured by distances walked by mites onto the tomato leaf surface after 20, 40 and 60 min. Spider mite repellence biotests indicated that higher densities of glandular trichomes (especially type VI decreased the distances walked by the mites onto the tomato leaf surface. Selection of plants with higher densities of glandular trichomes can be an efficient criterion to obtain tomato genotypes with higher resistance (repellence to spider mites.O objetivo deste trabalho foi avaliar a eficiência da seleção para maior densidade de tricomas glandulares na resistência (repelência ao ácaro Tetranychus urticae, em populações de tomate derivadas do cruzamento interespecífico Lycopersicon esculentum x L. hirsutum var. glabratum PI 134417. Foram avaliados 19 genótipos quanto à densidade de tricomas, que incluíram 12 derivados de populações avançadas de retrocruzamentos, obtidos a partir do cruzamento original L. esculentum x L. hirsutum var. glabratum PI 134417. Nas faces abaxial e adaxial dos folíolos, realizaram-se as contagens e os tricomas foram classificados em glandulares tipo IV e VI, outros glandulares (tipo I e VII e não glandulares. A repelência aos ácaros foi medida pela distância média, percorrida pelo

Quality Control in Mammography: Image Quality and Patient Doses

International Nuclear Information System (INIS)

Ciraj Bjelac, O.; Arandjic, D.; Boris Loncar, B.; Kosutic, D.

2008-01-01

Mammography is method of choice for early detection of breast cancer. The purpose of this paper is preliminary evaluation the mammography practice in Serbia, in terms of both quality control indicators, i.e. image quality and patient doses. The survey demonstrated considerable variations in technical parameters that affect image quality and patients doses. Mean glandular doses ranged from 0.12 to 2.8 mGy, while reference optical density ranged from 1.2 to 2.8. Correlation between image contrast and mean glandular doses was demonstrated. Systematic implementation of quality control protocol should provide satisfactory performance of mammography units and maintain satisfactory image quality and keep patient doses as low as reasonably practicable. (author)

Radiation doses from mammography in Australia

International Nuclear Information System (INIS)

Thomson, J.E.M.; Young, B.F.; Young, J.G.; Tingey, D.R.C.

1991-05-01

During 1989-90 the Australian Radiation Laboratory conducted a postal survey of at least 90% of the mammographic facilities in Australia. The primary aim of the survey was to measure the mean glandular dose (MGD) and the X-ray beam half value layer (HVL) for a typical mammograph. The MGD and HVL were measured with a specially designed tissue equivalent monitor. In all, 258 mammographic centres were surveyed. It was found that for centres using film-screen imaging, the average mean glandular dose was 1.83 mGy for centres using grids and 0.84 mGy for centres not using grids. In addition to the MGD and HVL, comprehensive statistical information was collected and data is presented on the types of equipment and techniques used, the number and age of patients and demographic distribution of centres. Results indicate that the use of a grid is the major factor determining dose and several other factors appear to have minor effects. In view of the distribution of MGD, it is recommended that the mean glandular dose per image, for a 5 cm compressed breast thickness, should not exceed 2.0 mGy when a grid is used and 1.0 mGy without a grid. 63 refs., 11 tabs., 15 figs

Breast internal dose measurements in a physical thoracic phantom

Energy Technology Data Exchange (ETDEWEB)

Silva, S.D.; Oliveira, M.A.; Castro, A.L.S.; Dias, H.G.; Nogueira, L.B.; Campos, T.P.R., E-mail: sadonatosilva@hotmail.com [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Departamento de Engenharia Nuclear; Hospital das Clinicas de Uberlandia, MG (Brazil). Departamento de Oncologia; Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Anatomia e Departamento de Imagem

2017-10-01

Radiotherapy is a cancer treatment intended to deposit the entire prescribed dose homogeneously into a target volume in order to eliminate the tumor and to spare the surrounding healthy tissues. This paper aimed to provide a dosimetric comparison between the treatment planning system (TPS) ECLIPSE from Varian Medical Systems and the internal dosimetric measurements in a breast phantom. The methodology consisted in performing a 3D conformal radiotherapy planning with two tangential opposite parallel fields applied to the synthetic breast in a thoracic phantom. The irradiation was reproduced in the Varian Linear accelerator, model SL - 20 Precise, 6 MV energy. EBT2 Radiochromic films, placed into the glandular equivalent tissue of the breast, were used to measure the spatial dose distribution. The absorbed dose was compared to those values predicted by the treatment planning system; besides, the dosimetric uncertainties were analyzed. The modal absorbed dose was in agreement with the prescribed value of 180 cGy, although few high dose points between 180 and 220 cGy were detected. The findings suggested a non-uniform dose distribution in the glandular tissue of the synthetic breast, similar to those found in the TPS, associated with the irregular anatomic breast shape and presence of inhomogeneities next to the thoracic wall generated by the low lung density. (author)

Caracterização e ontogenia dos tricomas glandulares de Ocimum selloi Benth. - Lamiaceae Characterization and ontogeny of the glandular trichomes of Ocimum selloi Benth. (Lamiaceae

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Letícia de Almeida Gonçalves

2010-12-01

Full Text Available Ocimum selloi Benth. (Lamiaceae é uma espécie nativa da América do Sul e na medicina popular tem sido usada devido suas propriedades analgésica, anti-inflamatória e antiespasmódica. O objetivo do presente trabalho foi identificar os tipos de tricomas glandulares que ocorrem nos órgãos vegetativos e reprodutivos de O. selloi e determinar a ontogenia desses tricomas. Ramos laterais em início de formação, folhas totalmente expandidas, flores em diferentes estádios de diferenciação, amostras de caule e do eixo das inflorescências foram analisados em microscopias de luz e eletrônica de varredura. Tricomas glandulares do tipo peltado e capitado subséssil foram observados no caule, nas folhas, no eixo da inflorescência e na superfície adaxial das sépalas. Nas sépalas foi encontrado, além dos tricomas secretores peltados e capitados subsésseis, o tricoma glandular capitado pedunculado. A ontogenia inicia-se com a expansão de uma célula protodérmica que, de acordo com a seqüência de divisões periclinais e anticlinais (ora simétricas, ora assimétricas, dá origem aos tricomas. A diferenciação dos tricomas glandulares peltados e capitados não é sincrônica e ocorre muito cedo no desenvolvimento da folha, do caule e do eixo floral.Ocimum selloi Benth. (Lamiaceae is native to South America and in traditional medicine has been used due to its analgesic, anti-inflammatory, and antispasmodic properties. The aim of this study was to identify the types of glandular trichomes that occur on the vegetative and reproductive organs of O. selloi and to determine trichome ontogeny. Lateral branches at the initial formation phase, fully opened leaves, flowers at different differentiation stages, and stem and inflorescence axes were analyzed under light and scanning electron microscopy. Glandular trichomes of the peltate and subsessile capitate types were observed on the stem, leaves, inflorescence axis and the adaxial surface of the

Higher glandular trichome density in tomato leaflets and repellence to spider mites

International Nuclear Information System (INIS)

Maluf, Wilson Roberto; Inoue, Irene Fumi; Ferreira, Raphael de Paula Duarte; Gomes, Luiz Antonio Augusto; Castro, Evaristo Mauro de; Cardoso, Maria das Gracas

2007-01-01

The objective of this work was to evaluate the feasibility of selection for higher glandular trichome densities, as an indirect criterion of selection for increasing repellence to spider mites Tetranychus urticae, in tomato populations derived from an interspecific cross between Lycopersicon esculentum x L. hirsutum var. glabratum PI 134417. Trichome densities were evaluated in 19 genotypes, including 12 from advanced backcross populations, derived from the original cross L. esculentum x L. hirsutum var. glabratum PI 134417. Counts were made both on the adaxial and abaxial leaf surfaces, and trichomes were classified into glandular types IV and VI, other glandular types (types I+VII), and nonglandular types. Mite repellence was measured by distances walked by mites onto the tomato leaf surface after 20, 40 and 60 min. Spider mite repellence biotests indicated that higher densities of glandular trichomes (especially type VI) decreased the distances walked by the mites onto the tomato leaf surface. Selection of plants with higher densities of glandular trichomes can be an efficient criterion to obtain tomato genotypes with higher resistance (repellence) to spider mites. (author)

A calibration approach to glandular tissue composition estimation in digital mammography

International Nuclear Information System (INIS)

Kaufhold, J.; Thomas, J.A.; Eberhard, J.W.; Galbo, C.E.; Trotter, D.E. Gonzalez

2002-01-01

The healthy breast is almost entirely composed of a mixture of fatty, epithelial, and stromal tissues which can be grouped into two distinctly attenuating tissue types: fatty and glandular. Further, the amount of glandular tissue is linked to breast cancer risk, so an objective quantitative analysis of glandular tissue can aid in risk estimation. Highnam and Brady have measured glandular tissue composition objectively. However, they argue that their work should only be used for 'relative' tissue measurements unless a careful calibration has been performed. In this work, we perform such a 'careful calibration' on a digital mammography system and use it to estimate breast tissue composition of patient breasts. We imaged 0%, 50%, and 100% glandular-equivalent phantoms of varying thicknesses for a number of clinically relevant x-ray techniques on a digital mammography system. From these images, we extracted mean signal and noise levels and computed calibration curves that can be used for quantitative tissue composition estimation. In this way, we calculate the percent glandular composition of a patient breast on a pixelwise basis. This tissue composition estimation method was applied to 23 digital mammograms. We estimated the quantitative impact of different error sources on the estimates of tissue composition. These error sources include compressed breast height estimation error, residual scattered radiation, quantum noise, and beam hardening. Errors in the compressed breast height estimate contribute the most error in tissue composition--on the order of ±7% for a 4 cm compressed breast height. The spatially varying scattered radiation will contribute quantitatively less error overall, but may be significant in regions near the skinline. It is calculated that for a 4 cm compressed breast height, a residual scatter signal error is mitigated by approximately sixfold in the composition estimate. The error in composition due to the quantum noise, which is the limiting

Genetic architecture of capitate glandular trichome density in florets of domesticated sunflower (Helianthus annuus L.)

Science.gov (United States)

Capitate glandular trichomes (CGT), one type of glandular trichomes, are most common in Asteraceae species. Capitate glandular trichomes can produce various secondary metabolites such as sesquiterpene lactones (STLs) and provide durable resistance to insect pests. In sunflower, CGT-based host resist...

Dual-energy digital mammography: Calibration and inverse-mapping techniques to estimate calcification thickness and glandular-tissue ratio

International Nuclear Information System (INIS)

Kappadath, S. Cheenu; Shaw, Chris C.

2003-01-01

Breast cancer may manifest as microcalcifications in x-ray mammography. Small microcalcifications, essential to the early detection of breast cancer, are often obscured by overlapping tissue structures. Dual-energy imaging, where separate low- and high-energy images are acquired and synthesized to cancel the tissue structures, may improve the ability to detect and visualize microcalcifications. Transmission measurements at two different kVp values were made on breast-tissue-equivalent materials under narrow-beam geometry using an indirect flat-panel mammographic imager. The imaging scenario consisted of variable aluminum thickness (to simulate calcifications) and variable glandular ratio (defined as the ratio of the glandular-tissue thickness to the total tissue thickness) for a fixed total tissue thickness--the clinical situation of microcalcification imaging with varying tissue composition under breast compression. The coefficients of the inverse-mapping functions used to determine material composition from dual-energy measurements were calculated by a least-squares analysis. The linear function poorly modeled both the aluminum thickness and the glandular ratio. The inverse-mapping functions were found to vary as analytic functions of second (conic) or third (cubic) order. By comparing the model predictions with the calibration values, the root-mean-square residuals for both the cubic and the conic functions were ∼50 μm for the aluminum thickness and ∼0.05 for the glandular ratio

Patient doses and radiation risks in film-screen mammography in Finland

International Nuclear Information System (INIS)

Servomaa, A.; Parviainen, T.; Komppa, T.

1995-01-01

Screen-film mamography is the most sensitive method for the early detection of breast cancer. Breast doses in mamography should be measured for several reasons, especially for the evaluation of patient risk in a screening programme, but also for the assessment and comparison of imaging techniques and equipment performance. In this study, the factors affecting patient doses were assessed by making performance and patient dose measurements; about 50 mammographic units used for screening were included in the study. The lifetime risk as a function of age at exposure was calculated using the average glandular dose, the relative risk model shown in the BEIR V report, and the breast cancer mortality in Finland. The mean surface dose of a 4.5 cm thick phantom was 6.3 mGy, and the mean glandular dose 1.0 mGy. Analysis of the surface dose with respect to film optical density, relative speed of film processing, sensitivity of image receptors, and antiscatter grid showed that the mean surface dose could be decreased by more than 50%. For the screened age group of 50 to 59 years, the risk of exposure-induced death (REID) of breast cancer is about 1.4 x 10 -6 mSv -1 , and the average loss of life expectancy due to the radiation-induced breast cancer deaths (LLE/REID) is about 9.5 years. (Author)

Antibacterial, modulatory activity of antibiotics and toxicity from Rhinella jimi (Stevaux, 2002) (Anura: Bufonidae) glandular secretions.

Science.gov (United States)

Sales, Débora Lima; Morais-Braga, Maria Flaviana Bezerra; Santos, Antonia Thassya Lucas Dos; Machado, Antonio Judson Targino; Araujo Filho, João Antonio de; Dias, Diógenes de Queiroz; Cunha, Francisco Assis Bezerra da; Saraiva, Rogério de Aquino; Menezes, Irwin Rose Alencar de; Coutinho, Henrique Douglas Melo; Costa, José Galberto Martins; Ferreira, Felipe Silva; Alves, Rômulo Romeu da Nóbrega; Almeida, Waltécio de Oliveira

2017-08-01

The increase in microorganisms with resistance to medications has caused a strong preoccupation within the medical and scientific community. Animal toxins studies, such as parotoid glandular secretions from amphibians, possesses a great potential in the development of drugs, such as antimicrobials, as these possess bioactive compounds. It was evaluated Rhinella jimi (Stevaux, 2002) glandular secretions against standard and multi-resistant bacterial strains; the effect of secretions combined with drugs; and determined the toxicity using two biologic in vivo models, and a in vitro model with mice livers. Standard strains were used for the determination of the Minimum Inhibitory Concentration (MIC), while for the modulatory activity of antibiotics, the clinical isolates Escherichia coli 06, Pseudomonas aeruginosa 03 and Staphylococcus aureus 10 were used. Modulatory activity was evaluated by the broth microdilution method with aminoglycosides and β-lactams as target antibiotics. The secretions in association with the antibiotics have a significant reduction in MIC, both the aminoglycosides and β-lactams. The toxicity and cytotoxicity results were lower than the values used in the modulation. R. jimi glandular secretions demonstrated clinically relevant results regarding the modulation of the tested antimicrobials. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Second-harmonic generation as a DNA malignancy indicator of prostate glandular epithelial cells

International Nuclear Information System (INIS)

Zheng-Fei, Zhuang; Han-Ping, Liu; Zhou-Yi, Guo; Xiao-Yuan, Deng; Shuang-Mu, Zhuo; Bi-Ying, Yu

2010-01-01

This paper first demonstrates second-harmonic generation (SHG) in the intact cell nucleus, which acts as an optical indicator of DNA malignancy in prostate glandular epithelial cells. Within a scanning region of 2.7 μm×2.7 μm in cell nuclei, SHG signals produced from benign prostatic hyperplasia (BPH) and prostate carcinoma (PC) tissues (mouse model C57BL/6) have been investigated. Statistical analyses (t test) of a total of 405 measurements (204 nuclei from BPH and 201 nuclei from PC) show that SHG signals from BPH and PC have a distinct difference (p < 0.05), suggesting a potential optical method of revealing very early malignancy in prostate glandular epithelial cells based upon induced biochemical and/or biophysical modifications in DNA. (geophysics, astronomy and astrophysics)

Células glandulares atípicas e câncer de colo uterino: revisão sistemática Atypical glandular cells and cervical cancer: systematic review

Directory of Open Access Journals (Sweden)

Juliana Pedrosa de Holanda Marques

2011-04-01

Full Text Available Atipias de células glandulares em esfregaços cervicovaginais é um achado citológico na rotina de rastreamento do câncer cervical, que aumentou nas últimas décadas. Sua constatação é importante clinicamente, pois é alta a percentagem de casos associados com doença cervical e endometrial de alto grau e câncer. Este trabalho avaliou, por meio de uma revisão sistemática, estudos que investigaram o perfil das lesões de colo uterino em avaliações histológicas de seguimento de pacientes já diagnosticadas com células glandulares atípicas. Foram excluídos os estudos cuja investigação diagnóstica não incluísse o diagnóstico histopatológico. Realizou-se uma busca abrangente de publicações no período de 1966 a 2009, nas bases do LILACS, SciELO, PubMed/Medline e Old Medline. Os artigos omitidos na busca eletrônica também foram incluídos. Estavam de acordo com os critérios de inclusão 19 artigos, que foram selecionados. Este estudo tem como objetivo avaliar se a atipia celular glandular observada inicialmente na citologia relacionava-se histologicamente com a presença de lesões benignas, pré-neoplásicas ou neoplásicas. Dos 19 estudos selecionados, 11 mostraram maior correlação entre atipia glandular com patologias benignas e seis com lesões escamosas pré-malignas.Atypical glandular cells are a common finding in cervical cytology in cervical cancer screening and its occurrence has increased in the last decades. The identification of these cells is clinically very important due to its association with cervical and endometrial dysplasic lesions and cancer. Using a systematic approach, this article reviewed studies investigating cervical lesions that are characteristic in patients previously diagnosed as having atypical glandular cells. Studies in which diagnostic investigation did not include histopathological diagnosis were excluded. A comprehensive search for available material in LILACS, SciELO, PubMed/ Medline

Phenylpropanoid biosynthesis in leaves and glandular trichomes of basil (Ocimum basilicum L.).

Science.gov (United States)

Deschamps, Cícero; Simon, James E

2010-01-01

Basil (Ocimum basilicum L.) essential oil phenylpropenes are synthesized and accumulate in peltate glandular trichomes and their content and composition depend on plant developmental stage. Studies on gene expression and enzymatic activity indicate that the phenylpropene biosynthetic genes are developmentally regulated. In this study, the methylchavicol accumulation in basil leaves and the enzyme activities and gene expression of both chavicol O-methyltransferase (CVOMT) and eugenol O-methyltransferase (EOMT) were investigated in all leaves at four plant developmental stages. Methylchavicol accumulation decreased over time as leaves matured. There was a significant correlation between methylchavicol accumulation and CVOMT (r(2) = 0.88) enzyme activity, suggesting that the levels of biosynthetic enzymes control the essential oil content. CVOMT and EOMT transcript expression levels, which decreased with leaf age, followed the same pattern in both whole leaves and isolated glandular trichomes, providing evidence that CVOMT transcript levels are developmentally regulated in basil glandular trichomes themselves and that differences in CVOMT expression observed in whole leaves are not solely the result of differences in glandular trichome density.

Evaluation of the population dose to the UK population from the National Health Service breast screening programme

International Nuclear Information System (INIS)

Faulkner, K.; Wallis, M. G.; Neilson, F.; Whitaker, C. J.

2008-01-01

In the United Kingdom National Health Service Breast Screening Programme (NHSBSP), women aged between 50 and 70 y are invited for mammography every 3 y. Screening histories for each woman, over four screening rounds, were analysed. Data from five screening programmes were used to select 57 425 women into the study. Cases were selected on the basis of being between the ages of 50 and 53 at the start of the NHSBSP (i.e. between 1989 and 1992). Assessment of the outcome for each screening round for each woman involved assigning a simple outcome code. Each of the possible pathways through the four screening rounds was analysed. This comprises of 500 possible pathways. This data enabled the following information to be determined: (i) The number of times a woman attended the screening programme. (ii) The number of women referred for assessment at each screening round. This information may be used to deduce the population dose to this group of women averaged over four screening rounds. Patient doses have been monitored since the programme's inception and are typically 4.5 mGy for two-view screening. It is possible to determine the mean glandular dose received by this cohort of women over four screening rounds by multiplying the number of examinations by the mean glandular dose for a typical woman. Allowance has to be made for the number of projections taken at each screening round. Once a woman has been screened, she may be invited back for further assessment if an abnormality is found on her mammogram. A stereotactic attachment is used to determine where to place the biopsy device. Although the dose received during a normal screening mammogram is well known, the dose for a stereotactic procedure and other assessment procedures is less well known, partly because only a small part of the breast is directly irradiated during stereo-taxis. However, the woman may have multiple exposures during this stage. A prospective survey of doses was completed to deduce the mean

Patient radiation dose during mammography procedures

International Nuclear Information System (INIS)

Mohamed, Swsan Awd Elkriem

2015-11-01

The objectives of this study were to estimate the patient dose in term of mean glandular dose and assist in optimization of radiation protection in mammographic procedures in Sudan. A total number of 107 patients were included. Four mammographic units were participated. Only one center was using automatic exposure control (AEC). The mean doses in (mGy) for the CC projection were 3.13, 1.24, 2.45 and 0.98 and for the MLO projection was 2.13, 1.26, 1.99 and 1.02 for centers A, B, C, and D, respectively. The total mean dose per breast from both projections was 5.26, 2.50, 4.44 and 1.99 mGy for centers A, B, C and D, respectively. The minimum mean glandular dose was found between the digital system which was operated under AEC and one of the manual selected exposure factors systems, this highlight possible optimization of radiation protection in the other manual selected systems. The kilo volt and the tube current time products should be selected correctly according to the breast thickness in both centers A and C. (author)

Células glandulares atípicas em esfregaços cervicovaginais: significância e aspectos atuais Atypical glandular cells in cervical smears: significance and current aspects

Directory of Open Access Journals (Sweden)

Adriana Bittencourt Campaner

2007-02-01

Full Text Available Células glandulares atípicas (AGC em esfregaços cervicovaginais são achados citológicos raros, porém de significado representativo. Sua incidência varia, na literatura, de 0,08% a 0,81%. O sistema Bethesda de 2001 classifica estas lesões glandulares como AGCs sem outras especificações, AGCs provavelmente neoplásicas, adenocarcinoma cervical in situ (AIS e adenocarcinoma invasivo. Das mulheres portadoras de AGC, grande parte não apresentará qualquer tipo de alteração histológica em avaliação subseqüente. Entretanto, em 17,4% a 62,2% dos casos serão encontradas lesões histológicas significativas, como neoplasias intra-epiteliais cervicais, AIS, neoplasias escamosas e glandulares, cervicais e endometriais, bem como neoplasias de outras localizações. O risco de doença significativa está relacionado à subdivisão de AGC encontrada. Em virtude da elevada probabilidade de anormalidades histológicas significativas em casos de AGC, a simples repetição citológica é insuficiente para o seguimento dessa condição. Esta atualização descreve a epidemiologia, a avaliação e a conduta das pacientes portadoras dessa anormalidade citológica.Atypical glandular cells (AGC on cervical smears are unusual but important cytologic diagnosis. The incidence of AGC ranges from 0.08% to 0.81 % of all cervical smears tests. The 2001 Bethesda System nomenclature classifies these glandular lesions as AGC not otherwise specified, AGC favor neoplasia, endocervical adenocarcinoma in situ (AIS and invasive adenocarcinoma. Of women with AGC smears, a great number will have no histologic abnormalities on further evaluation. However, 17.4% to 62.2% are found to have significant histologic lesions such as cervical intraepithelial neoplasia, AIS, squamous and glandular cancers from sites farther the cervix and endometrium. The risk of significant disease is related to the AGC subclassification that was found. Because of the high likelihood that AGC

Mammographic dose survey in the Czech Republic

International Nuclear Information System (INIS)

Novak, Leos; Rada, Jiri

2006-01-01

At present, it is generally accepted that the average dose to the glandular tissue is the most reasonable dose descriptor in mammography with regard to the risk of breast cancer induced by ionizing radiation. It is advantageous to use the quantity mean glandular dose M.G.D. for setting of diagnostic reference levels (D.R.L.) as well, although the quantity is not directly measurable as it is the case of D.R.L. quantities for other imaging modalities. The reason is that a directly measurable quantity suitable for mammography, incident air kerma Ki, depends a lot on a beam quality. The influence of the beam quality (expressed by tube voltage, half value layer and combination of anode/filter material) is already included in calculation of mean glandular dose. To assess a radiation burden of patients due to mammography at a national level a representative dose survey is needed to carry out. Such a study provides statistically significant dose data for setting of the national diagnostic reference levels. National Radiation Protection Institute is performing the study in the Czech Republic since the year 2005.On a basis of presented data, it could be concluded, that the situation in the Czech Republic with respect to patient doses in mammography is encouraging and that the requirements of European Commission are well fulfilled. However, it is obvious, that the obtained results can not be considered as statistically significant at the moment, because the data were not collected from a representative sample of centers, which should observe a distribution of X-ray unit types, type of a mammographic center (screening/non screening ones) and also a locality of a center. The dose survey still continues to cover the whole Czech Republic with the main task to determine new national diagnostic reference levels and to find out optimized standards for carrying out the examinations with respect to patient doses and image quality. (authors)

Mammographic dose survey in the Czech Republic

Energy Technology Data Exchange (ETDEWEB)

Novak, Leos [National Radiation Protection Institute, Prague (Czech Republic); Rada, Jiri [National Radiation Protection Institute, Ostrava (Czech Republic)

2006-07-01

At present, it is generally accepted that the average dose to the glandular tissue is the most reasonable dose descriptor in mammography with regard to the risk of breast cancer induced by ionizing radiation. It is advantageous to use the quantity mean glandular dose M.G.D. for setting of diagnostic reference levels (D.R.L.) as well, although the quantity is not directly measurable as it is the case of D.R.L. quantities for other imaging modalities. The reason is that a directly measurable quantity suitable for mammography, incident air kerma Ki, depends a lot on a beam quality. The influence of the beam quality (expressed by tube voltage, half value layer and combination of anode/filter material) is already included in calculation of mean glandular dose. To assess a radiation burden of patients due to mammography at a national level a representative dose survey is needed to carry out. Such a study provides statistically significant dose data for setting of the national diagnostic reference levels. National Radiation Protection Institute is performing the study in the Czech Republic since the year 2005.On a basis of presented data, it could be concluded, that the situation in the Czech Republic with respect to patient doses in mammography is encouraging and that the requirements of European Commission are well fulfilled. However, it is obvious, that the obtained results can not be considered as statistically significant at the moment, because the data were not collected from a representative sample of centers, which should observe a distribution of X-ray unit types, type of a mammographic center (screening/non screening ones) and also a locality of a center. The dose survey still continues to cover the whole Czech Republic with the main task to determine new national diagnostic reference levels and to find out optimized standards for carrying out the examinations with respect to patient doses and image quality. (authors)

Micromorphology of glandular structures in Echium vulgare L. flowers

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Elżbieta Weryszko-Chmielewska

2012-12-01

Full Text Available The micromorphology of selected elements of Echium vulgare L. flowers was investigated, with special attention to the structure of the nectaries and the stigma of the pistil as well as types of trichomes occurring on the surface of the calyx. The nectary had the shape of an uneven disc located around the lower region of the four-parted ovary of the pistil. The glandular cells formed a tier with a height of 330 μm and a radial width of 144 μm. Nectar was secreted onto the nectary surface through anomocytic stomata located at the level of other epidermal cells. Most of the stomata were open, with a different dimension of the pore. Their largest number was observed at the base of the nectary, and 462 stomata were noted on the whole surface of the nectary. The cuticle on the surface of the guard cells formed fine, circular striae. The subsidiary cells formed striated cuticular ornamentation, with the striae arranged radially in the direction of the stoma, whereas on the surface of other epidermal cells the striae formed an arrangement with different directions. The epidermis on the surface of the stigma formed regularly arranged papillae with a fan-shaped, expanded upper part which had corrugated outer walls, whereas the base of the cell formed a widened small column. The epidermis of the abaxial part of the calyx was covered by numerous non-glandular trichomes of different length which were made up of one or several cells. The glandular trichomes in the epidermis of the calyx grew with smaller density compared to the protective trichomes, and they were composed of a 1-2-celled stalk and a glandular head.

A Survey On Mean Glandular Dose From Full-Field Digital Mammography Systems, Operate Using Mo/ Mo And W/Rh Target/ Filter Combinations

International Nuclear Information System (INIS)

Noriah Jamal; Siti Selina Abdul Hamid; Humairah Samad Cheung; Siti Kamariah Che Mohamed; Ellyda Muhammed Nordin; Radhiana Hassan; Rehir Dahalan

2013-01-01

We had conducted a survey on Mean Glandular Dose (MGD) from Full-Field Digital Mammography systems (FFDM) operate using Molybdenum/ Molybdenum (Mo/ Mo) and Tungsten/ Rhodium (W/ Rh) target/ filter combinations. A survey was carried out at two randomly selected mammography centres in Malaysia, namely National Cancer Society and International Islamic University of Malaysia. The first centre operates using a W/ Rh, while the second centre operates using an Mo/ Mo target/ filter combinations. On the basis of recorded information, data on mammographic views, MGD, age and Compressed Breast Thickness (CBT) were recorded for 100 patients, for each mammographic centre respectively. The MGD data were analyzed for variation with age group, with 5 years increment. The MGD data were also analyzed for variation with CBT, with 5 mm increment. We found that for both CC and MLO views, FFDM systems operated using Mo/ Mo and W/ Rh target/ filter combinations present the same trend on MGD. The average MGD decreases as age increases. While average MGD increases with the increasing of CBT. However, FFDM system operates using Mo/ Mo gives higher MGD as compared with FFDM system operates using W/ Rh. (author)

Cadmium induced changes in subcellular glutathione contents within glandular trichomes of Cucurbita pepo L.

Science.gov (United States)

Kolb, Dagmar; Müller, Maria; Zellnig, Günther; Zechmann, Bernd

2010-07-01

Plants cope with cadmium (Cd) stress by complexation with phytochelatins (Pc), metallothioneins and glutathione and sequestration within vacuoles. Especially glutathione was found to play a major role in Cd detoxification as Cd shows a high binding affinity towards thiols and as glutathione is a precursor for Pc synthesis. In the present study, we have used an immunohistochemical approach combined with computer-supported transmission electron microscopy in order to measure changes in the subcellular distribution of glutathione during Cd-stress in mesophyll cells and cells of different glandular trichomes (long and short stalked) of Cucurbita pepo L. subsp. pepo var. styriaca GREB: . Even though no ultrastructural alterations were observed in leaf and glandular trichome cells after the treatment of plants with 50 microM cadmium chloride (CdCl(2)) for 48 h, all cells showed a large decrease in glutathione contents. The strongest decrease was found in nuclei and the cytosol (up to 76%) in glandular trichomes which are considered as a major side of Cd accumulation in leaves. The ratio of glutathione between the cytosol and nuclei and the other cell compartments was strongly decreased only in glandular trichomes (more than 50%) indicating that glutathione in these two cell compartments is especially important for the detoxification of Cd in glandular trichomes. Additionally, these data indicate that large amounts of Cd are withdrawn from nuclei during Cd exposure. The present study gives a detailed insight into the compartment-specific importance of glutathione during Cd exposure in mesophyll cells and glandular trichomes of C. pepo L. plants.

Monte Carlo simulation studies for the determination of microcalcification thickness and glandular ratio through dual-energy mammography

Science.gov (United States)

Del Lama, L. S.; Godeli, J.; Poletti, M. E.

2017-08-01

The majority of breast carcinomas can be associated to the presence of calcifications before the development of a mass. However, the overlapping tissues can obscure the visualization of microcalcification clusters due to the reduced contrast-noise ratio (CNR). In order to overcome this complication, one potential solution is the use of the dual-energy (DE) technique, in which two different images are acquired at low (LE) and high (HE) energies or kVp to highlight specific lesions or cancel out tissue background. In this work, the DE features were computationally studied considering simulated acquisitions from a modified PENELOPE Monte Carlo code. The employed irradiation geometry considered typical distances used in digital mammography, a CsI detection system and an updated breast model composed of skin, microcalcifications and glandular and adipose tissues. The breast thickness ranged from 2 to 6 cm with glandularities of 25%, 50% and 75%, where microcalcifications with dimensions from 100 up to 600 μm were positioned. In general, results pointed an efficiency index better than 87% for the microcalcification thicknesses and better than 95% for the glandular ratio. The simulations evaluated in this work can be used to optimize the elements from the DE imaging chain, in order to become a complementary tool for the conventional single-exposure images, especially for the visualization and estimation of calcification thicknesses and glandular ratios.

Influence of breast composition and interseed attenuation in dose calculations for post-implant assessment of permanent breast 103Pd seed implant

International Nuclear Information System (INIS)

Afsharpour, Hossein; Beaulieu, Luc; Pignol, Jean-Philippe; Keller, Brian; Carrier, Jean-Francois; Reniers, Brigitte; Verhaegen, Frank

2010-01-01

The impact of tissue heterogeneity and interseed attenuation is studied in post-implant evaluation of five clinical permanent breast 103 Pd seed implants using the Monte Carlo (MC) dose calculation method. Dose metrics for the target (PTV) as well as an organ at risk (skin) are used to visualize the differences between a TG43-like MC method and more accurate MC methods capable of considering the breast tissue heterogeneity as well as the interseed attenuation. PTV dose is reduced when using a breast tissue model instead of water in MC calculations while the dose to the skin is increased. Furthermore, we investigate the effect of varying the glandular/adipose proportion of the breast tissue on dose distributions. The dose to the PTV (skin) decreases (increases) with the increasing adipose proportion inside the breast. In a complete geometry and compared to a TG43-like situation, the average PTV D 90 reduction varies from 3.9% in a glandular breast to 35.5% when the breast consists entirely of adipose. The skin D 10 increases by 28.2% in an entirely adipose breast. The results of this work show the importance of an accurate and patient-dependent breast tissue model to be used in the dosimetry for this kind of low energy implant.

Glandular trichomes in Connarus suberosus (Connaraceae: distribution, structural organization and probable functions

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João Donizete Denardi

2012-03-01

Full Text Available Connarus suberosus is a typical species of the Brazilian Cerrado biome, and its inflorescences and young vegetative branches are densely covered by dendritic trichomes. The objective of this study was to report the occurrence of a previously undescribed glandular trichome of this species. The localization, origin and structure of these trichomes were investigated under light, transmission and scanning electron microscopy. Collections were made throughout the year, from five adult specimens of Connarus suberosus near Botucatu, São Paulo, Brazil, including vegetative and reproductive apices, leaves and fruits in different developmental stages, as well as floral buds and flowers at anthesis. Glandular trichomes (GTs occurred on vegetative and reproductive organs during their juvenile stages. The GTs consisted of a uniseriate, multicellular peduncle, whose cells contain phenolic compounds, as well as a multicellular glandular portion that accumulates lipids. The glandular cell has thin wall, dense cytoplasm (with many mitochondria, plastids and dictyosomes, and a large nucleus with a visible nucleolus. The starch present in the plastids was hydrolyzed during the synthesis phase, reducing the density of the plastid stroma. Some plastids were fused to vacuoles, and some evidence suggested the conversion of plastids into vacuoles. During the final activity stages of the GTs, a darkening of the protoplasm was observed in some of the glandular cells, as a programmed cell death; afterwards, became caducous. The GTs in C. suberosus had a temporal restriction, being limited to the juvenile phase of the organs. Their presence on the exposed surfaces of developing organs and the chemical nature of the reserve products, suggest that these structures are food bodies. Field observations and detailed studies of plant-environment interactions, as well as chemical analysis of the reserve compounds, are still necessary to confirm the role of these GTs as feeding

Evaluation of the image quality criteria and study of doses in a mammography department

International Nuclear Information System (INIS)

Alcantara, Marcela Costa

2009-01-01

The mammographic image quality criteria published by European Commission were implemented in three mammography equipment of a same radiology department in a hospital of Sao Paulo city. Among the mammography equipment, two use the screen-film system and one of them uses the indirect digital system. During the data collection, it was noted the need to conduct a study about image rejection in each mammography equipment. Therefore, this study was realized and, after that, the results in each mammography equipment of image rejection and image percentage that present each quality criterion it were compared. At the same time of this studies, it was realized other study about surface entrance dose and average glandular dose. These doses it was estimated based on different methods published by different groups of researcher, for all combinations anode filter available in the equipment. To estimate the surface entrance dose following the methodology published in Avenue's' guide and the average glandular dose following the Wu' methodology, it was developed a phantom, in different thicknesses of acrylic, to simulate a breast. Finally, the image quality it was associated with the dose received by patient. The digital equipment shows better results in the evaluation of quality criteria, lower rate of image rejection and lower values of average glandular dose and surface entrance dose in all methods studied. But it is not sufficient, because is not adequate for patients with great breast. (author)

Dose absorbed in adults and children thyroid due to the I{sup 123} using the dosimetry MIRD and Marinelli; Dosis absorbida en tiroides de adultos y ninos debido al I{sup 123} utilizando las dosimetrias MIRD y Marinelli

Energy Technology Data Exchange (ETDEWEB)

Vasquez, M.; Castillo, C.; Cabrera, C.; Sarachaga, R.; Castaneda, J. [Universidad Nacional de Trujillo, Av. Juan Pablo II s/n, Ciudad Universitaria, Trujillo (Peru); Diaz, E., E-mail: marvva@hotmail.com [Universidade Federal do Rio Grande do Sul, Av. Paulo Gamma 110, Bairro Farropilhas, Porto Alegre, RS 90040-060 (Brazil)

2014-08-15

Using the dosimetry MIRD, and representation Cristy-Eckerman in the thyroid gland and organs of their bio-kinetics when I{sup 123} (Iodine) is used, the study demonstrates that the absorbed dose by the gland of an adult, children, and newly born, is their auto-dose, independent of the compartments number of their bio-kinetics. The dosimetric contributions of the organs of their bio-kinetics are insignificant. Their results are not significantly different to those obtained by the formalism MARINELLI (auto-dose) when it uses a sphere like glandular representation. In consequence, the kinetic model corresponding to the glandular representation decreases to a compartment, where the gland can also be represented like a sphere. (Author)

Evaluation of patient dose in some mammography centres in Iran

International Nuclear Information System (INIS)

Paknyat, A.; Samarin, E. R. P.; Jeshvaghane, N. A.; Paydar, R.; Fasaei, B.; Karamloo, A.; Khosravi, H. R.; Deevband, M. R.

2011-01-01

High diagnostic sensitivity and specificity while maintaining the least dose to the patient is the ideal mammography. The objective of this work was to evaluate patient dose and image quality of mammograms to propose corrective actions. The image quality for 1242 patient in 7 mammography facilities in Tehran city was evaluated based on selected image quality criteria using a three-point scale. Clinical image quality, the entrance surface air kerma, the average glandular dose and optical density of films for standard PMMA phantom of 4.5 cm thickness were evaluated. The results showed that up to 72 % of mammograms were in good condition to be diagnosed, and only about 3.4 % of the images were unacceptable or with suboptimal quality. The entrance surface air kerma values were in the range of 3.8-10.5 mGy, average glandular dose 0.5-1.8 mGy and optical density of films 0.74-2.03. The image quality evaluation after correction actions, periodic image quality evaluation and using the correct equipment certainly will improve patient dose. (authors)

Review of Dosimetric Methods for Mammography in the UK Breast Screening Programme

International Nuclear Information System (INIS)

Young, K.C.; Ramsdale, M.L.; Bignell, F.

1998-01-01

The two methods used to monitor dose in mammography in the UK Breast Screening Programme are reviewed. The first is the measurement of mean glandular dose to a standard breast. The second is the estimation of mean glandular dose for individual women using the X ray exposure factors. Neither method takes account of variations in breast composition and the effect of this on estimates of glandular dose are reported. Applying the standard breast model using PMMA resulted in substantial overestimates of breast doses for women with large compressed breast thicknesses because they tend to have low glandular content. Conversely the use of post-exposure data to estimate the MGDs in women attending screening with large breasts resulted in underestimates of their doses unless the relatively low levels of glandularity were taken into account. When estimating the MGDs for breasts of different sizes, it is important that the models and methods used take account of the strong variation in breast composition with compressed thickness. (author)

Mineral nutrient uptake from prey and glandular phosphatase activity as dual test of carnivory in semidesert plants with glandular leaves suspected of carnivory

Czech Academy of Sciences Publication Activity Database

Plachno, B.J.; Adamec, Lubomír; Huet, H.

2009-01-01

Roč. 104, č. 4 (2009), s. 649-654 ISSN 0305-7364 Institutional research plan: CEZ:AV0Z60050516 Keywords : mineral nutrient uptake * phosphatases * glandular leaves Subject RIV: EF - Botanics Impact factor: 3.501, year: 2009

Identifying three ecological chemotypes of Xanthium strumarium glandular trichomes using a combined NMR and LC-MS method.

Science.gov (United States)

Chen, Fangfang; Hao, Fuhua; Li, Changfu; Gou, Junbo; Lu, Dayan; Gong, Fujun; Tang, Huiru; Zhang, Yansheng

2013-01-01

Xanthanolides, as the sesquiterpene lactones, are reportedly the major components for the pharmacological properties of X. strumarium L. species. Phytochemical studies indicated that the glandular structures on the surface of plant tissues would form the primary sites for the accumulation of this class of the compounds. As the interface between plants and their natural enemies, glandular trichomes may vary with respect to which of their chemicals are sequestered against different herbivores in different ecologies. However, to date, no data are available on the chemical characterisation of X. strumarium glandular cells. In this study, the trichome secretions of the X. strumarium species originating from nineteen unique areas across eleven provinces in China, were analysed by HPLC, LC-ESI-MS and NMR. For the first time three distinct chemotypes of X. strumarium glandular trichomes were discovered along with the qualitative and quantitative evaluations of their presence of xanthanolides; these were designated glandular cell Types I, II, and III, respectively. The main xanthanolides in Type I cells were 8-epi-xanthatin and xanthumin while no xanthatin was detected. Xanthatin, 8-epi-xanthatin, and xanthumin dominated in Type II cells with comparable levels of each being present. For Type III cells, significantly higher concentrations of 8-epi-xanthatin or xanthinosin (relative to xanthatin) were detected with xanthinosin only being observed in this type. Further research will focus on understanding the ecological and molecular mechanism causing these chemotype differences in X. strumarium glandular structures.

Identifying three ecological chemotypes of Xanthium strumarium glandular trichomes using a combined NMR and LC-MS method.

Directory of Open Access Journals (Sweden)

Fangfang Chen

Full Text Available Xanthanolides, as the sesquiterpene lactones, are reportedly the major components for the pharmacological properties of X. strumarium L. species. Phytochemical studies indicated that the glandular structures on the surface of plant tissues would form the primary sites for the accumulation of this class of the compounds. As the interface between plants and their natural enemies, glandular trichomes may vary with respect to which of their chemicals are sequestered against different herbivores in different ecologies. However, to date, no data are available on the chemical characterisation of X. strumarium glandular cells. In this study, the trichome secretions of the X. strumarium species originating from nineteen unique areas across eleven provinces in China, were analysed by HPLC, LC-ESI-MS and NMR. For the first time three distinct chemotypes of X. strumarium glandular trichomes were discovered along with the qualitative and quantitative evaluations of their presence of xanthanolides; these were designated glandular cell Types I, II, and III, respectively. The main xanthanolides in Type I cells were 8-epi-xanthatin and xanthumin while no xanthatin was detected. Xanthatin, 8-epi-xanthatin, and xanthumin dominated in Type II cells with comparable levels of each being present. For Type III cells, significantly higher concentrations of 8-epi-xanthatin or xanthinosin (relative to xanthatin were detected with xanthinosin only being observed in this type. Further research will focus on understanding the ecological and molecular mechanism causing these chemotype differences in X. strumarium glandular structures.

Dose surveys in two digital mammography units using DICOM headers

International Nuclear Information System (INIS)

Tsalafoutas, I.; Michalaki, C.; Papagiannopoulou, C.; Efstathopoulos, E.

2012-01-01

Background and objective: Digital mammography units store images in DICOM format. Thus, data regarding the acquisition parameters are available within DICOM headers, including among others, the anode/filter combination, tube potential and tube current exposure time product, compressed breast thickness, entrance surface air kerma (ESAK) and mean glandular dose (MGD). However, manual extraction of these data for the verification of the displayed values' accuracy and for dose survey purposes is time consuming. Our objective was to develop a method that enables the automation of such procedures. Materials and methods: Two hundred mammographic examinations (800 mammograms) performed in two digital units (GE, Essential) were recorded on CD-roms. Using appropriate software (DICOM Info Extractor) all dose related DICOM headers were extracted into a Microsoft Excel based spreadsheet, containing embedded algorithms for the calculation of ESAK and MGD according to Dance et al (Phys. Med. Biol. 45, 2000) methodology. Results: The ESAK and MGD values stored in the DICOM headers were compared with those calculated and in most cases were within ±10%. The basic difference among the two mammographic units is that, the older one calculates MGD assuming a breast composition 50% glandular-50% adipose tissue, while the newer one calculates the actual breast glandularity and stores this value in a DICOM header. The average MGD values were 1.21 mGy and 1.38 mGy, respectively. Conclusion: For the units studied, the ESAK and MGD values stored in DICOM headers are reliable. Utilizing tools for their automatic extraction provides an easy way to perform dose surveys. (authors)

Papel dos tricomas glandulares da folha do tomateiro na oviposição de Tuta absoluta Role of tomato leaf glandular trichomes on oviposition of Tuta absoluta

Directory of Open Access Journals (Sweden)

Elsa Gilardón

2001-03-01

Full Text Available Os tricomas glandulares presentes nas folhas e ramos das plantas do gênero Lycopersicon são responsáveis pela secreção de metabólitos de diferentes naturezas. A presença de alguns desses compostos tem sido associada à resistência do tomate a diferentes insetos. A traça-do-tomateiro, Tuta absoluta (Meyrick, é uma das pragas mais nocivas da América do Sul. O adulto oviposita sobre as folhas do tomate e suas larvas abrem galerias no mesófilo das folhas, ramos, flores e frutos. As espécies silvestres do tomate conservam a capacidade de biossintetizar compostos químicos que lhes conferem resistência a esta praga. No presente trabalho, foi avaliada a preferência para oviposição desse inseto sobre folhas com e sem tricomas glandulares de L. esculentum (Mill. cv. Uco Plata, suscetível, e de L. hirsutum f. glabratum (Mull. PI 134417, espécie silvestre afim ao tomate, e resistente à traça. Os resultados sugerem que as fêmeas ovipositam indistintamente sobre as folhas de ambas espécies, independentemente da presença, ou não, dos tricomas glandulares. E a presença destes e de seus exsudatos não têm efeito inibidor na oviposição do inseto.In the genus Lycopersicon, different metabolites are secreted by the glandular trichomes of leaves and stems. These compounds have been associated to different tomato pests resistance. The South American tomato pinworm, Tuta absoluta (Meyrick, is one of the most harmful pests in South America. The females oviposit on tomato leaves and the larvae mine the leaf mesophyl, stems, flowers and fruits. Some wild accessions of Lycopersicon keep their capacity to synthesize allelochemicals that protect them from the pest. In this paper a comparison was made between the tomato pinworm oviposition on leaves with and without trichomes of L. esculentum (Mill. cv. Uco Plata, a susceptible cultivar, and L. hirsutum f. glabratum (Mull. PI 134417, a resistant wild accession. Results suggest that the female

Two-dose strategies for human papillomavirus vaccination: how well do they need to protect?

Science.gov (United States)

Jit, Mark; Choi, Yoon Hong; Laprise, Jean-François; Boily, Marie-Claude; Drolet, Mélanie; Brisson, Marc

2014-05-30

Two-dose human papillomavirus (HPV) vaccine schedules may provide short-term protection but their long-term population impact is unknown. Two models of HPV transmission and associated cervical disease (squamous and glandular, neoplasia and cancer) were fitted to data from England and Canada on HPV epidemiology, sexual behaviour, cervical screening outcomes and cervical cancer incidence. Models suggest that at 40-80% coverage, if two-dose schedules protect vaccinees for 20 years, then the benefits of the third dose are small. If two doses protect for 10 years, then the third dose may prevent as many cancers as the first two. At 80% coverage, numbers needed to receive a third dose to prevent an additional cancer are 5900-110,000 (England), 3000-5100 (Canada) with 20 years two-dose protection, and 2000-5300 (England), 760-950 (Canada) with 10 years two-dose protection. Results enable decision makers to quantify risks associated with two-dose schedules despite remaining uncertainties in vaccine duration and cross-protection. Copyright © 2014 Elsevier Ltd. All rights reserved.

Negative ion 'chip-based' nanospray tandem mass spectrometry for the analysis of flavonoids in glandular trichomes of Lychnophora ericoides Mart. (Asteraceae).

Science.gov (United States)

Gobbo-Neto, Leonardo; Gates, Paul J; Lopes, Norberto P

2008-12-01

This paper reports a method for the analysis of secondary metabolites stored in glandular trichomes, employing negative ion 'chip-based' nanospray tandem mass spectrometry. The analyses of glandular trichomes from Lychnophora ericoides, a plant endemic to the Brazilian 'cerrado' and used in traditional medicine as an anti-inflammatory and analgesic agent, led to the identification of five flavonoids (chrysin, pinocembrin, pinostrobin, pinobanksin and 3-O-acetylpinobanksin) by direct infusion of the extracts of glandular trichomes into the nanospray ionisation source. All the flavonoids have no oxidation at ring B, which resulted in a modification of the fragmentation pathways compared with that of the oxidised 3,4-dihydroflavonoids already described in the literature. The absence of the anti-inflammatory and antioxidant di-C-glucosylflavone vicenin-2, or any other flavonoid glycosides, in the glandular trichomes was also demonstrated. The use of the 'chip-based' nanospray QqTOF apparatus is a new fast and useful tool for the identification of secondary metabolites stored in the glandular trichomes, which can be useful for chemotaxonomic studies based on metabolites from glandular trichomes.

Radioimmunoassay of glandular kallikrein in human plasma after partial purification by immunoaffinity column

International Nuclear Information System (INIS)

Nishimura, Kazutaka; Inoue, Yoshikazu; Kokubu, Tatsuo

1987-01-01

Glandular kallikrein in human plasma was partially purified by immunoaffinity column and was measured by a radioimmunoassay (RIA). Plasma was diluted with an equal volume of 10 mmol/l sodium phosphate buffer, pH 7.4, containing 0.9% NaCl (PBS) and was applied to an immunoaffinity column from which glandular kallikrein was eluted with 3 mol/l NaSCN (20 ml). The enzymic fraction was concentrated with an Amicon PM 10 filter and dialyzed against PBS. The final recovery of the enzyme was 51.6 ± 1.6%, determined by using [ 125 I]kallikrein. The usable range of the standard curve covered 2.5-100 ng/tube. The coefficient of variation within the series was 5.9%, and the coefficient of variation between the series was 7.6%. In healthy controls, the plasma content of glandular kallikrein was 1.36 ± 0.39 ng/ml. In patients with acute pancreatitis, the plasma concentration was 8.02 ± 6.15 ng/ml, significantly different from the control group. (Auth.)

Dose and risk evaluation in digital mammography using computer modeling

Energy Technology Data Exchange (ETDEWEB)

Correa, Samanda Cristine Arruda; Souza, Edmilson Monteiro de, E-mail: scorrea@nuclear.ufrj.b, E-mail: emonteiro@nuclear.ufrj.b [Centro Universitario Estadual da Zona Oeste (CCMAT/UEZO), Rio de Janeiro, RJ (Brazil); Silva, Humberto de Oliveira, E-mail: hbetorj@gmail.co [Universidade Federal do Rio de Janeiro IF/UFRJ, RJ (Brazil). Inst. de Fisica; Silva, Ademir Xavier da; Lopes, Ricardo Tadeu; Magalhaes, Sarah Braga, E-mail: ademir@nuclear.ufrj.b, E-mail: ricardo@lin.ufrj.b, E-mail: smagalhaes@nuclear.ufrj.b [Coordenacao dos Programas de Pos-Graduacao de Engenharia (COPPE/UFRJ), RJ (Brazil). Programa de Engenharia Nuclear

2010-07-01

Digital mammography has been introduced in several countries in the last years. The new technology requires new optimising methods considering for instance the increased possibility of changing the absorbed dose, mainly in modern mammographic systems that allow the operator to choose the beam quality by varying the tube voltage, and filter and target materials. In this work, the Monte Carlo code MCNPX is used in order to investigate how the average glandular dose vary with tube voltage (23-32 kV) and anode-filter combination (Mo-Mo,Mo-Rh and Rh-Rh) in digital mammographic examinations. Furthermore, the risk of breast cancer incidence attributable to mammography exams was estimated using the Biological Effects of Ionizing Radiations (BEIR) VII Committee Report. The results show that the risk of breast cancer incidence in women younger than 30 years of age tends to decrease significantly using Rh-Rh anode-filter combination and higher tube voltage. For women older than 50 years of age the variation of tube voltage, and anode-filter combination did not influence the risk values considerably. (author)

Dose and risk evaluation in digital mammography using computer modeling

International Nuclear Information System (INIS)

Correa, Samanda Cristine Arruda; Souza, Edmilson Monteiro de; Silva, Humberto de Oliveira; Silva, Ademir Xavier da; Lopes, Ricardo Tadeu; Magalhaes, Sarah Braga

2010-01-01

Digital mammography has been introduced in several countries in the last years. The new technology requires new optimising methods considering for instance the increased possibility of changing the absorbed dose, mainly in modern mammographic systems that allow the operator to choose the beam quality by varying the tube voltage, and filter and target materials. In this work, the Monte Carlo code MCNPX is used in order to investigate how the average glandular dose vary with tube voltage (23-32 kV) and anode-filter combination (Mo-Mo,Mo-Rh and Rh-Rh) in digital mammographic examinations. Furthermore, the risk of breast cancer incidence attributable to mammography exams was estimated using the Biological Effects of Ionizing Radiations (BEIR) VII Committee Report. The results show that the risk of breast cancer incidence in women younger than 30 years of age tends to decrease significantly using Rh-Rh anode-filter combination and higher tube voltage. For women older than 50 years of age the variation of tube voltage, and anode-filter combination did not influence the risk values considerably. (author)

Characterization of fibrillar collagens and extracellular matrix of glandular benign prostatic hyperplasia nodules.

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Tyler M Bauman

Full Text Available Recent studies have associated lower urinary tract symptoms (LUTS in men with prostatic fibrosis, but a definitive link between collagen deposition and LUTS has yet to be demonstrated. The objective of this study was to evaluate ECM and collagen content within normal glandular prostate tissue and glandular BPH, and to evaluate the association of clinical parameters of LUTS with collagen content.Fibrillar collagen and ECM content was assessed in normal prostate (48 patients and glandular BPH nodules (24 patients using Masson's trichrome stain and Picrosirius red stain. Second harmonic generation (SHG imaging was used to evaluate collagen content. Additional BPH tissues (n = 47 were stained with Picrosirius red and the association between clinical parameters of BPH/LUTS and collagen content was assessed.ECM was similar in normal prostate and BPH (p = 0.44. Total collagen content between normal prostate and glandular BPH was similar (p = 0.27, but a significant increase in thicker collagen bundles was observed in BPH (p = 0.045. Using SHG imaging, collagen content in BPH (mean intensity = 62.52; SEM = 2.74 was significantly higher than in normal prostate (51.77±3.49; p = 0.02. Total collagen content was not associated with treatment with finasteride (p = 0.47 or α-blockers (p = 0.52, pre-TURP AUA symptom index (p = 0.90, prostate-specific antigen (p = 0.86, post-void residual (PVR; p = 0.32, prostate size (p = 0.21, or post-TURP PVR (p = 0.51. Collagen content was not associated with patient age in patients with BPH, however as men aged normal prostatic tissue had a decreased proportion of thick collagen bundles.The proportion of larger bundles of collagen, but not total collagen, is increased in BPH nodules, suggesting that these large fibers may play a role in BPH/LUTS. Total collagen content is independent of clinical parameters of BPH and LUTS. If fibrosis and overall ECM deposition are

Localization of a defensive volatile 4-hydroxy-4-methylpentan-2-one in the capitate glandular trichomes of Oenothera glazioviana

Institute of Scientific and Technical Information of China (English)

Yanyun Tan; Desen Li; Juan Hua; Shihong Luo; Yan Liu; Shenghong Li

2017-01-01

Glandular trichomes of plants produce a wide variety of secondary metabolites which are considered as major defensive chemicals. The capitate glandular trichomes of Oenothera glazioviana (Onagraceae) were collected with laser microdissection and analyzed by gas chromatography-mass spectrometry. The volatile compound 4-hydroxy-4-methylpentan-2-one (1) was identified. We found that compound 1 displays antimicrobial, insecticidal, and phytotoxic activities. These results suggest that compound 1 might function as a defensive compound in the capitate glandular trichomes of O. glazioviana against pathogens, insect herbivores, and presumably competitive plants as well.

Localization of a defensive volatile 4-hydroxy-4-methylpentan-2-one in the capitate glandular trichomes of Oenothera glazioviana

Directory of Open Access Journals (Sweden)

Yanyun Tan

2017-06-01

Full Text Available Glandular trichomes of plants produce a wide variety of secondary metabolites which are considered as major defensive chemicals. The capitate glandular trichomes of Oenothera glazioviana (Onagraceae were collected with laser microdissection and analyzed by gas chromatography–mass spectrometry. The volatile compound 4-hydroxy-4-methylpentan-2-one (1 was identified. We found that compound 1 displays antimicrobial, insecticidal, and phytotoxic activities. These results suggest that compound 1 might function as a defensive compound in the capitate glandular trichomes of O. glazioviana against pathogens, insect herbivores, and presumably competitive plants as well.

Breast compression and radiation dose in two different mammographic oblique projections: 45 and 60 deg

International Nuclear Information System (INIS)

Brnic, Zoran; Hebrang, Andrija

2001-01-01

Introduction: Standard mammography includes two views, craniocaudal and medio-lateral oblique. Depending on patient's body constitution, central beam angle in mediolateral oblique projection may vary, with 45 deg. being suitable for the majority of patients in routine daily practice. With continuous improvement in X-ray technology and radiographers' training, the risk of radiation induced cancerogenesis is considerably reduced and acceptable when compared to benefit. However, the risk still exists, being cumulative and directly related to absorbed glandular dose. There is no minimal dose of radiation which is absolutely harmless, and every effort to reduce the dose is welcome. In this retrospective study two different angles (45 vs. 60 deg.) of mediolateral oblique view were compared according to radiation dose and efficacy of breast compression. Patients and methods: In 52 women, additional 60 deg. oblique films were done after craniocaudal and mediolateral oblique 45 deg.-films, with the same kVp and positioning technique. Breast thickness, time-current products (mA s) and absorbed doses were compared between 45 deg. - and 60 deg.-films. Subgroups of women with large, small, prominent and pendulous breasts were analyzed separately, following the same methodology as for the whole group. Results: mA s were 11.5% lower and compression 7% better with an angle of 60 deg. than with 45 deg. In the subgroup of women with small breasts, mA s values were 13% lower and compression 9% better with 60 deg. than with 45 deg., while in the subgroup with large breasts, mA s were 9% lower and compression 5% better. In the subgroup of patients with pendulous breasts, mA s values were 12% lower and compression 10% better with 60 deg. than with 45 deg., while in the subgroup with prominent breasts, mA s values were 4% lower and compression 3% better. Absorbed glandular dose was estimated to be approximately 20% lower when an oblique mammogram was done with 60 deg. instead of 45 deg

CT measurement of breast glandular tissue and its association with testicular cancer

Energy Technology Data Exchange (ETDEWEB)

Klang, Eyal [Tel Aviv University, Department of Radiology, Chaim Sheba Medical Center, Tel Aviv (Israel); The Chaim Sheba Medical Center, Tel Hashomer (Israel); Rozendorn, Noa; Raskin, Steve; Portnoy, Orith; Sklair, Miri; Marom, Edith M.; Konen, Eli; Amitai, Michal M. [Tel Aviv University, Department of Radiology, Chaim Sheba Medical Center, Tel Aviv (Israel)

2017-02-15

To evaluate the associations between breast glandular tissues diameters as determined by CT and b-hCG levels, histological types, tumour spread and prognosis in patients with testicular germ cell tumour. Ninety-four patients with pre-treatment CT scan and markers (b-hCG, AFP, LDH) were retrospectively collected. A radiologist measured diameters in all CT examinations and correlation between diameters and log (b-hCG) was assessed (Pearson's coefficient). The ability of measured diameters to predict lymphatic and distant haematogenous metastatic spread was evaluated (ROC curves). The associations between measured diameter cut-off values of 20 and 25 mm and International Germ Cell Cancer Collaborative Group (IGCCCG) classification, lymphatic and distant haematogenous metastatic spread and histological subtypes were evaluated (chi squared test). Breast glandular diameters correlated to log(b-hCG) (r = 0.579) and predicted distant haematogenous metastatic spread (AUC = 0.78). Worse prognosis (intermediate or poor IGCCCG) was shown for 20 mm (27.3 vs. 4.2 %, p = 0.005) and 25 mm (33.3 vs. 6.1 %, p = 0.014). A diameter of 25 mm was associated with non-seminoma (91.7 vs. 48.8 %, p = 0.005). Breast glandular tissue diameters correlated with log(b-hCG) and predicted distant haematogenous metastases. Twenty and 25 mm were associated with worse prognosis and 25 mm was able to distinguish between seminoma and non-seminoma. (orig.)

Papel da 2-tridecanona e dos tricomas glandulares tipo VI na resistência do tomateiro a Tuta absoluta Role of 2-tridecanone and type VI glandular trichome on tomato resistance to Tuta absoluta

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Elsa Gilardón

2001-07-01

Full Text Available O metabólito secundário 2-tridecanona, secretado pelos tricomas glandulares tipo VI das folhas de tomateiro silvestre, Lycopersicon hirsutum L., confere-lhe resistência a uma grande variedade de insetos, inclusive a traça-do-tomateiro, Tuta absoluta (Meyrick. O objetivo do trabalho foi avaliar a concentração de 2- tridecanona, a densidade de tricomas glandulares tipo VI e o grau de infestação da traça-do-tomateiro na cultivar suscetível 'Uco Plata' (Lycopersicon esculentum Mill., na linhagem resistente PI 134417 (L. hirsutum f. glabratum e em suas progênies F1 e F2. Foram avaliadas ainda as possíveis associações entre a concentração de 2-tridecanona, a densidade de tricomas glandulares tipo VI e o grau de infestação da traça-do-tomateiro. O grau médio de infestação da traça-do-tomateiro em 'Uco Plata' foi significativamente superior ao obtido em PI 134417. Ainda que a concentração de 2-tridecanona tenha sido significativamente superior no parental resistente, a presença deste metabólito somente explicaria parcialmente a resistência (R² = 8,17%. Não se detectaram diferenças significativas na densidade de tricomas tipo VI entre o parental suscetível e o resistente. Este comportamento ocorreu independentemente do conteúdo de 2-tridecanona e do grau de infestação da traça-do-tomateiro.The secondary metabolite 2-tridecanone, secreted by the type VI glandular trichomes present in the leaves of Lycopersicon hirsutum L., make it resistant to a great variety of insects, including the tomato pinworm, Tuta absoluta (Meyrick. The 2-tridecanone concentration, the type VI glandular trichome densities and the pinworm infestation degree were evaluated on the Lycopersicon esculentum Mill. susceptible cultivar 'Uco Plata', on the Lycopersicon hirsutum f. glabratum resistant accession PI 134417 and on their F1 and F2. The mean infestation degree with pinworm larvae was significantly higher in 'Uco Plata' than in PI 134417. The 2

Morphology and histochemistry of glandular trichomes of Orobanche alba Stephan ex Willd

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Aneta Sulborska

2014-04-01

Full Text Available Orobanche alba Stephan ex Willd is an achlorophyllous root parasite rare in Poland. It prefers dry and sunny slopes, xerothermic grasslands and pastures, mountain pastures, light scrubs, and rock fissures and ledges. The hosts of O. alba include Thymus polytrichus A. ern. ex Borbás, Clinopodium vulgare L. and Origanum vulgare L. The tick and fleshy 10-70 cm high stem in this species bears an inflorescence composed of zygomorphic, white or yellow “spotted” flowers covered by purple glandular trichomes. Glandular trichomes of this type are also borne on other parts of the plant, i.e. on the stem, scaly leaves, sepals, filaments, and the style. The secondary metabolites secreted by the glandular trichomes are related to defense of plants against the attack of herbivores and pathogens or act as attractants to pollinators or for fruit dispersal. The micromorphology and histochemistry of the glandular trichomes in O. alba were examined using scanning electron and light microscopes. In order to determine the type of secondary metabolites produced by the trichomes, the flowing histochemical assays were used: Sudan III and neutral red for detection of lipophilic compounds, IKI for detection of starch, and FeCl3 for detection of phenolic compounds. The peltate glandular trichomes of O. alba were characterised by a varied length (0.15‑0.48 mm and different activity phases. The trichome was composed of one larger basal epidermal cell, 1-3 hyaline stalk cells with a striated cuticle, a neck cell with a smooth cuticle on the surface, and a globose head formed of 8-18 secretory cells arranged in a circle. Many stalk cells of the trichomes, particularly those located on the corolla, contained anthocyanins, which give the trichomes dark carmine colour. In turn, the colour of the heads was dependent on trichome age: the heads were brown in older trichomes and yellow in younger hairs. Secretion was produced by both young and older trichomes. It penetrated

Glandular odontogenic cyst: A case report

International Nuclear Information System (INIS)

Tambawaia, Shahnaz S.; Karjodkar, Freny R.; Yadav, Archana; Sansare, Kaustubh; Sontakke, Subodh

2014-01-01

Glandular odontogenic cysts (GOCs) are rare intrabony solitary or multiloculated cysts of odontogenic origin. The importance of GOCs lies in the fact that they exhibit a propensity for recurrence similar to keratocystic odontogenic tumors and that they may be confused microscopically with central mucoepidermoid carcinoma. Thus, the oral and maxillofacial radiologists play an important role in definitive diagnosis of GOC based on distinctive cases; though they are rare. In large part, this is due to the GOC's complex and frequently non-specific histopathology. This report describes a case of GOC occurrence in the posterior mandibular ramus region in a 17-year-old female, which is a rare combination of site, age, and gender for occurrence.

Glandular odontogenic cyst: A case report

Energy Technology Data Exchange (ETDEWEB)

Tambawaia, Shahnaz S.; Karjodkar, Freny R.; Yadav, Archana; Sansare, Kaustubh; Sontakke, Subodh [Nair Hospital Dental College, Mumbai (India)

2014-03-15

Glandular odontogenic cysts (GOCs) are rare intrabony solitary or multiloculated cysts of odontogenic origin. The importance of GOCs lies in the fact that they exhibit a propensity for recurrence similar to keratocystic odontogenic tumors and that they may be confused microscopically with central mucoepidermoid carcinoma. Thus, the oral and maxillofacial radiologists play an important role in definitive diagnosis of GOC based on distinctive cases; though they are rare. In large part, this is due to the GOC's complex and frequently non-specific histopathology. This report describes a case of GOC occurrence in the posterior mandibular ramus region in a 17-year-old female, which is a rare combination of site, age, and gender for occurrence.

Doses mammography: from phantom to the patient

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Cross, P [Gammasonic Radiological Services, Pty., Ltd., Five Dock, NSW (Australia)

1994-02-01

While the use of a reference phantom is essential for dosimetry in acceptance testing and in regular quality control checks of a mammographic X-ray unit, it is also of importance to be able to estimate the patient dose in each individual investigation. Radiographic and physical data were analysed for a total of 212 women who were screened at three locations participating in a breast screening programme. The radiologists made estimates of the individual breast composition (%glandular/adipose ratio) at the film reporting sessions, and then the glandular doses were calculated by the auditor according to the NCRP 85 methodology. Arising from the data analysis of this dosimetry survey, a method is proposed to determine objectively patient breast composition from the photo-timed mAs for a given film optical density setting. This permits the NCRP calculations to be extended from breasts of 'average' (50/50) composition to breasts of individually determined composition. The diversity of the results between the three locations emphasises the need for regular audits of a mammographic X-ray unit's performance by an experienced radiological physicists, at least annually or after any major interventional service on the unit. 11 refs., 6 tabs., 4 figs.

Image Quality and Radiation Dose Assessment of a Digital Mammography System

International Nuclear Information System (INIS)

Isa, N. M.; Hassan, W. M. S. W.; Abdullah, W. A. K. W.; Othman, F.; Ramli, A. A. M.

2010-01-01

Image quality and radiation dose of a direct amorphous selenium digital mammography system were considered in terms of contrast to noise ratio (CNR) and average glandular dose (AGD). They were measured for various qualities and breast phantom thicknesses with different types of breast tissue composition to determine optimal radiation quality and dose. Three sets of breast tissue equivalent slabs (30%:70%, 50%:50% and 70%:30% glandular-adipose) with thickness of 2 cm to 7 cm and 0.2 mm aluminum foil were used to provide certain CNR. Two different combinations of anode/ilter material and a wide range of tube voltages were employed for each phantom thickness. Phantom images with grid were acquired using automatic exposure control (AEC) mode for each thickness. Phantom images without grid were also obtained in manual exposure mode by selecting the same anode/filter combination and kVp as the image obtained with grid at the same thickness, but varying mAs of 10 to 200 mAs. Optimization indicated that relatively high energy beam qualities should be used with a greater dose to compensate for lower energy x-rays. The results also indicate that current AEC setting for a fixed detector is not optimal.

Normal tissue dose-effect models in biological dose optimisation

International Nuclear Information System (INIS)

Alber, M.

2008-01-01

Sophisticated radiotherapy techniques like intensity modulated radiotherapy with photons and protons rely on numerical dose optimisation. The evaluation of normal tissue dose distributions that deviate significantly from the common clinical routine and also the mathematical expression of desirable properties of a dose distribution is difficult. In essence, a dose evaluation model for normal tissues has to express the tissue specific volume effect. A formalism of local dose effect measures is presented, which can be applied to serial and parallel responding tissues as well as target volumes and physical dose penalties. These models allow a transparent description of the volume effect and an efficient control over the optimum dose distribution. They can be linked to normal tissue complication probability models and the equivalent uniform dose concept. In clinical applications, they provide a means to standardize normal tissue doses in the face of inevitable anatomical differences between patients and a vastly increased freedom to shape the dose, without being overly limiting like sets of dose-volume constraints. (orig.)

Methodology for correlations between doses and detectability in standard mammographic images: application in Sao Paulo state

International Nuclear Information System (INIS)

Furquim, Tania Aparecida Correia

2005-01-01

Measurements using mammography units were performed in loco in 50 health establishments, randomly sampled from an equipment list of the Cadastro Nacional de Estabelecimentos de Saude (Health Establishments Brazilian Catalog). For the measurements six phantoms were utilized to establish different quality criteria and to evaluate doses in different breast thicknesses. Two different methods of measuring average glandular doses (AGD) were applied, and measurements of entrance surface doses (ESD) were also realized, in order to obtain mean values to Sao Paulo State. A study relating distribution and properties of different mammography trademarks with doses was performed. The sensitometry of processors allowed a quantification of the film-processing contrast index, A g , establishing a state mean value. The phantom images allowed the evaluation of detection limits of structures as microcalcifications, fibers, and masses, and state mean values were established for: spatial resolution (on surface and glandular breast position); image contrast; and detection expert ability from phantom images in two situations: before knowing the image targets and after viewing of a target map. Then, the results were compared to target detections in laboratory environment. Based on dose results, A g , image contrast, maximum contrast, and detection ratio, a relationship between them was determined. The results show that, in Sao Paulo State, mean glandular doses were lower than reference levels considering the Wu method, and close to or above reference levels for ail phantoms considering the Dance method. The ESD was always close to or above reference levels. The A g presented a mean value of (10,42 ± 0,20) for Sao Paulo State, and the image contrast was lower than the required limits established by the phantom manufacturers. The high contrast resolution showed that mammography units presented the expected values of line pair per mm in the State. The detectability evaluation of local

Image quality and dose assessment in digital breast tomosynthesis: A Monte Carlo study

International Nuclear Information System (INIS)

Baptista, M.; Di Maria, S.; Oliveira, N.; Matela, N.; Janeiro, L.; Almeida, P.; Vaz, P.

2014-01-01

Mammography is considered a standard technique for the early detection of breast cancer. However, its sensitivity is limited essentially due to the issue of the overlapping breast tissue. This limitation can be partially overcome, with a relatively new technique, called digital breast tomosynthesis (DBT). For this technique, optimization of acquisition parameters which maximize image quality, whilst complying with the ALARA principle, continues to be an area of considerable research. The aim of this work was to study the best quantum energies that optimize the image quality with the lowest achievable dose in DBT and compare these results with the digital mammography (DM) ones. Monte Carlo simulations were performed using the state-of-the-art computer program MCNPX 2.7.0 in order to generate several 2D cranio-caudal (CC) projections obtained during an acquisition of a standard DBT examination. Moreover, glandular absorbed doses and photon flux calculations, for each projection image, were performed. A homogeneous breast computational phantom with 50%/50% glandular/adipose tissue composition was used and two compressed breast thicknesses were evaluated: 4 cm and 8 cm. The simulated projection images were afterwards reconstructed with an algebraic reconstruction tool and the signal difference to noise ratio (SDNR) was calculated in order to evaluate the image quality in DBT and DM. Finally, a thorough comparison between the results obtained in terms of SDNR and dose assessment in DBT and DM was performed. - Highlights: • Optimization of the image quality in digital breast tomosynthesis. • Calculation of photon energies that maximize the signal difference to noise ratio. • Projections images and dose calculations through the Monte Carlo (MC) method. • Tumor masses and microcalcifications included in the MC model. • A dose saving of about 30% can be reached if optimal photon energies are used

SU-F-I-53: Coded Aperture Coherent Scatter Spectral Imaging of the Breast: A Monte Carlo Evaluation of Absorbed Dose

Energy Technology Data Exchange (ETDEWEB)

Morris, R [Durham, NC (United States); Lakshmanan, M; Fong, G; Kapadia, A [Carl E Ravin Advanced Imaging Laboratories, Durham, NC (United States); Greenberg, J [Duke University, Durham, NC (United States)

2016-06-15

Purpose: Coherent scatter based imaging has shown improved contrast and molecular specificity over conventional digital mammography however the biological risks have not been quantified due to a lack of accurate information on absorbed dose. This study intends to characterize the dose distribution and average glandular dose from coded aperture coherent scatter spectral imaging of the breast. The dose deposited in the breast from this new diagnostic imaging modality has not yet been quantitatively evaluated. Here, various digitized anthropomorphic phantoms are tested in a Monte Carlo simulation to evaluate the absorbed dose distribution and average glandular dose using clinically feasible scan protocols. Methods: Geant4 Monte Carlo radiation transport simulation software is used to replicate the coded aperture coherent scatter spectral imaging system. Energy sensitive, photon counting detectors are used to characterize the x-ray beam spectra for various imaging protocols. This input spectra is cross-validated with the results from XSPECT, a commercially available application that yields x-ray tube specific spectra for the operating parameters employed. XSPECT is also used to determine the appropriate number of photons emitted per mAs of tube current at a given kVp tube potential. With the implementation of the XCAT digital anthropomorphic breast phantom library, a variety of breast sizes with differing anatomical structure are evaluated. Simulations were performed with and without compression of the breast for dose comparison. Results: Through the Monte Carlo evaluation of a diverse population of breast types imaged under real-world scan conditions, a clinically relevant average glandular dose for this new imaging modality is extrapolated. Conclusion: With access to the physical coherent scatter imaging system used in the simulation, the results of this Monte Carlo study may be used to directly influence the future development of the modality to keep breast dose to

Doses in mammography. Preliminary study

International Nuclear Information System (INIS)

Marquez P, F.; Acosta R, N.; Universidad Nacional Mayor de San Marcos, Lima; Benavente, T.; Universidad Nacional Mayor de San Marcos, Lima; Poma, M.

2002-01-01

Mammography is the most important method to detect lesions in the breast with this technique one can detect small tumours before clear clinical symptoms appear. Mammographic image of require high quality standards due that the extremely low contrast between the normal and pathological areas in the breast, eg.g., they have similar attenuation and absorption coefficient. The x-ray mammographic systems, used in this study are Senographe 500t and Senographe DMR, a detector with a RadCal ionization chambers calibrated to the qualities of mammographic x-ray beams, and a breast simulator that is a phantoms of polymethylmethacrylate (PMMA) of several thicknesses with the equivalence of 50% of the glandular tissue. The results obtained indicate that the values of doses at the entrance surface of a breast (DES) are greater the reference value 20 mGy to 5,0 cm of PMMA and the values of the mean glandular dose (MGD) exceed the reference value of 2,1 mGy for 5,1 cm of compressed thick breast. We consider that the values high of the EDS and MGD are due that the x-ray systems no meeting in good condition or for used of x-ray spectra no suitable, so is recommendable be carried out test of quality control to the x-ray systems and also realize studies, or characterize the of x-ray mammographic spectra

Abnormal ion content, hydration and granule expansion of the secretory granules from cystic fibrosis airway glandular cells

International Nuclear Information System (INIS)

Baconnais, S.; Delavoie, F.; Zahm, J.M.; Milliot, M.; Terryn, C.; Castillon, N.; Banchet, V.; Michel, J.; Danos, O.; Merten, M.; Chinet, T.; Zierold, K.; Bonnet, N.; Puchelle, E.; Balossier, G.

2005-01-01

The absence or decreased expression of cystic fibrosis transmembrane conductance regulator (CFTR) induces increased Na + absorption and hyperabsorption of the airway surface liquid (ASL) resulting in a dehydrated and hyperviscous ASL. Although the implication of abnormal airway submucosal gland function has been suggested, the ion and water content in the Cystic Fibrosis (CF) glandular secretory granules, before exocytosis, is unknown. We analyzed, in non-CF and CF human airway glandular cell lines (MM-39 and KM4, respectively), the ion content in the secretory granules by electron probe X-ray microanalysis and the water content by quantitative dark field imaging on freeze-dried cryosections. We demonstrated that the ion content (Na + , Mg 2+ , P, S and Cl - ) is significantly higher and the water content significantly lower in secretory granules from the CF cell line compared to the non-CF cell line. Using videomicroscopy, we observed that the secretory granule expansion was deficient in CF glandular cells. Transfection of CF cells with CFTR cDNA or inhibition of non-CF cells with CFTR inh -172, respectively restored or decreased the water content and granule expansion, in parallel with changes in ion content. We hypothesize that the decreased water and increased ion content in glandular secretory granules may contribute to the dehydration and increased viscosity of the ASL in CF

Differentiating between endocervical glandular neoplasia and high grade squamous intraepithelial lesions in endocervical crypts: cytological features in ThinPrep and SurePath cervical cytology samples.

Science.gov (United States)

Thiryayi, Sakinah A; Marshall, Janet; Rana, Durgesh N

2009-05-01

A recent audit at our institution revealed a higher number of cases diagnosed as endocervical glandular neoplasia on ThinPrep (TP) cervical cytology samples (9 cases) as opposed to SurePath (SP) (1 case), which on histology showed only high-grade cervical intraepithelial neoplasia (CIN) with endocervical crypt involvement (CI). We attempted to ascertain the reasons for this finding by reviewing the available slides of these cases, as well as slides of cases diagnosed as glandular neoplasia on cytology and histology; cases diagnosed as high-grade squamous intraepithelial lesions (HSIL) on cytology which had CIN with CI on histology and cases with mixed glandular and squamous abnormalities diagnosed both cytologically and histologically. Single neoplastic glandular cells and short pseudostratified strips were more prevalent in SP than TP with the cell clusters in glandular neoplasia 3-4 cells thick, in contrast to the dense crowded centre of cell groups in HSIL with CI. The cells at the periphery of groups can be misleading. Cases with HSIL and glandular neoplasia have a combination of the features of each entity in isolation. The diagnosis of glandular neoplasia remains challenging and conversion from conventional to liquid based cervical cytology requires a period of learning and adaptation, which can be facilitated by local audit and review of the cytology slides in cases with a cytology-histology mismatch. (c) 2009 Wiley-Liss, Inc.

Atypical squamous and glandular cells of undetermined significance (ASCUS and AGUS) of the uterine cervix.

Science.gov (United States)

Cenci, M; Vecchione, A

2000-01-01

ASCUS (Atypical Squamous Cells of Undetermined Significance) and AGUS (Atypical Glandular Cells of Undetermined Significance), or AGCUS, are two acronyms introduced in 1988 by The Bethesda System (TBS) for reporting borderline cytological changes in cervical cytology. ASCUS and AGUS categories should be subclassified. Five ASCUS subgroups were proposed: 1) ASCUS due to processing defects, 2) with "mature" cytoplasm, 3) in post-menopausal women (a--in the setting of atrophy and b--with estrogen stimulation), 4) atypical metaplasia, and 5) ASCUS with keratinized cytoplasm. AGUS subgroups may be subcategorized in endometrial or endocervical on the basis of origin. Endocervical AGUS should be further qualified, but the analysis of atypical glandular cells may be really difficult and the conclusive diagnosis is frequently "AGUS not otherwise specified". The subclassification of ASCUS and AGUS is useful for an appropriate clinical management, but pertinent patient information (such as age, date of last menstrual period, mechanical therapies, tamoxifen therapy, and others) is needed to avoid an overdiagnosis and consequently an overtreatment. In fact various subgroups require different clinical management. Therefore, an effective communication between cytopathologists and referring physicians is essential in the analysis of squamous and glandular atypias.

Development of low-dose photon-counting contrast-enhanced tomosynthesis with spectral imaging.

Science.gov (United States)

Schmitzberger, Florian F; Fallenberg, Eva Maria; Lawaczeck, Rüdiger; Hemmendorff, Magnus; Moa, Elin; Danielsson, Mats; Bick, Ulrich; Diekmann, Susanne; Pöllinger, Alexander; Engelken, Florian J; Diekmann, Felix

2011-05-01

To demonstrate the feasibility of low-dose photon-counting tomosynthesis in combination with a contrast agent (contrast material-enhanced tomographic mammography) for the differentiation of breast cancer. All studies were approved by the institutional review board, and all patients provided written informed consent. A phantom model with wells of iodinated contrast material (3 mg of iodine per milliliter) 1, 2, 5, 10, and 15 mm in diameter was assessed. Nine patients with malignant lesions and one with a high-risk lesion (atypical papilloma) were included (all women; mean age, 60.7 years). A multislit photon-counting tomosynthesis system was utilized (spectral imaging) to produce both low- and high-energy tomographic data (below and above the k edge of iodine, respectively) in a single scan, which allowed for dual-energy visualization of iodine. Images were obtained prior to contrast material administration and 120 and 480 seconds after contrast material administration. Four readers independently assessed the images along with conventional mammograms, ultrasonographic images, and magnetic resonance images. Glandular dose was estimated. Contrast agent was visible in the phantom model with simulated spherical tumor diameters as small as 5 mm. The average glandular dose was measured as 0.42 mGy per complete spectral imaging tomosynthesis scan of one breast. Because there were three time points (prior to contrast medium administration and 120 and 480 seconds after contrast medium administration), this resulted in a total dose of 1.26 mGy for the whole procedure in the breast with the abnormality. Seven of 10 cases were categorized as Breast Imaging Reporting and Data System score of 4 or higher by all four readers when reviewing spectral images in combination with mammograms. One lesion near the chest wall was not captured on the spectral image because of a positioning problem. The use of contrast-enhanced tomographic mammography has been demonstrated successfully in

Radiation doses in mammography as planning parameters for premature breast cancer tracking programs

International Nuclear Information System (INIS)

Souza Ferreira, Rubemar de.

1994-01-01

Radiation doses are the main parameters applied to the evaluation of mammographic radiological impact. This study, for a sample of 407 women, were analyzed, through the thermoluminescent dosimetry, radiation doses in the surface of skin and glandular absorbed doses for cranio-caudal view. The results show the presence of a large dose range to the same mammographic procedure, which, analyzed enclosed with 585 facilities, suggest be necessary the standardization of the mammographic technique. From that results, with the additive model, the excess of breast cancer (radioinduced) and lifetime loss risk, for age groups between 30 and 70 years were estimated. Is demonstrated that the benefits from dedicated mammography, overcome the relationship among the epidemiological aspects of breast cancer and ionizing radiation as an harmful agent, which may show an important correlation for large exposed populations, point out the importance of the continuous risk and benefit evaluation to the new technologies introduced. (author). 86 refs., 40 figs., 14 tabs

Radiation doses and some aspects of image quality in mammography facilities in New Zealand

International Nuclear Information System (INIS)

Williamson, B.D.P.; Poletti, J.L.

1990-02-01

Until recently, mammography in New Zealand was performed largely with adapted conventional x-ray machines with tungsten anode x-ray tubes. Over the last several years these have virtually all been replaced by dedicated mammography machines with molybdenum anode x-ray tubes. To assess current trends in radiation doses to patients and central aspects of image quality, some 37 mammography x-ray machines were surveyed during 1988-89. The mean glandular dose per film for 30 and 45 mm thick breast-equivalent phantoms was determined using thermoluminescent dosimetry. Imagings of simulated microcalcifications (specks) and a contrast-detail phantom were assessed. Accuracy of calibration of the x-ray machines and quality of film processing were also tested. Details of the survey results are given. Mean glandular tissue doses per cranio-caudal films were generally well within the recommended guidelines. Mammography facilities differed in their ability to delete simulated calcification specks. Mammographic equipment was found to be generally well adjusted. Speed and contrast of film processing were found to vary widely implying that this is a major cause of the variations in dose and image quality. An annex outlines a quality assurance programme for maintenance of optimal physical image quality and control of radiation doses. 55 refs., 21 tabs., 17 figs., 2 ills

Genetics and biochemistry of collagen binding-triggered glandular differentiation in a human colon carcinoma cell line

International Nuclear Information System (INIS)

Pignatelli, M.; Bodmer, W.F.

1988-01-01

The authors have examined the interaction between collagen binding and epithelial differentiation by using a human colon carcinoma cell line (SW1222) that can differentiate structurally when grown in a three-dimensional collagen gel to form glandular structures. As much as 66% inhibition of glandular differentiation can be achieved by addition to the culture of a synthetic peptide containing the Arg-Gly-Asp-Thr (RGDT) sequence, which is a cell recognition site found in collagen. Arg-Gly-Asp-Thr also inhibited the cell attachment to collagen-coated plates. Chromosome 15 was found in all human-mouse hybrid clones that could differentiate in the collagen gel and bind collagen. Both binding to collagen and glandular differentiation of the hybrid cells were also inhibited by Arg-Gly-Asp-Thr as for the parent cell line SW1222. The ability of SW1222 cells to express the differentiated phenotype appears, therefore, to be determined by an Arg-Gly-Asp-directed collagen receptor on the cell surface that is controlled by a gene on chromosome 15

Impact of the digitalisation of mammography on performance parameters and breast dose in the Flemish Breast Cancer Screening Programme.

Science.gov (United States)

Timmermans, Lore; De Hauwere, An; Bacher, Klaus; Bosmans, Hilde; Lemmens, Kim; Bleyen, Luc; Van Limbergen, Erik; Martens, Patrick; Van Steen, Andre; Mortier, Griet; Van Herck, Koen; Thierens, Hubert

2014-08-01

To investigate the impact of digitalisation on performance parameters and breast dose of the Flemish Breast Cancer Screening Programme. Both computed (CR) and direct radiography (DR) are compared with screen-film mammography (SFM). Data from 975,673 mammographic examinations were collected from units which underwent digitalisation from SFM to CR (41 units) or DR (72 units) in the period 2005-2011. Performance indicators were obtained by consulting the Screening Programme database. Phantom and patient dosimetry data were acquired from the physical technical quality assurance of the programme. Digitalisation induced no significant change in cancer detection rate (CDR), percentage of ductal carcinomas in situ and percentage of breast cancers smaller than 1 cm. A decrease in false-positive results and third readings was observed, which was a time-related observation. After digitalisation, positive predictive value (PPV) increased and recall rates decreased. Compared with SFM, an increase of 30% in mean glandular dose (MGD) was found for CR, while a similar change in the opposite direction was found for DR. No major differences in performance parameters after digitalisation were found. Transition of SFM to CR resulted in a higher MGD and associated lower detection-over-induction ratio (DIR), while the change to DR induced an improvement of DIR. • Performance parameters showed no major differences after digitalisation to CR or DR. • Transition from SFM to CR results in a higher mean glandular dose. • Transition from SFM to DR results in a lower mean glandular dose.

Radiation doses in mammography as planning parameters for premature breast cancer tracking programs; Doses de radiacao em mamografias como parametros de planejamento para programas de rastreamento do cancer precoce da mama

Energy Technology Data Exchange (ETDEWEB)

Souza Ferreira, Rubemar de

1994-12-31

Radiation doses are the main parameters applied to the evaluation of mammographic radiological impact. This study, for a sample of 407 women, were analyzed, through the thermoluminescent dosimetry, radiation doses in the surface of skin and glandular absorbed doses for cranio-caudal view. The results show the presence of a large dose range to the same mammographic procedure, which, analyzed enclosed with 585 facilities, suggest be necessary the standardization of the mammographic technique. From that results, with the additive model, the excess of breast cancer (radioinduced) and lifetime loss risk, for age groups between 30 and 70 years were estimated. Is demonstrated that the benefits from dedicated mammography, overcome the relationship among the epidemiological aspects of breast cancer and ionizing radiation as an harmful agent, which may show an important correlation for large exposed populations, point out the importance of the continuous risk and benefit evaluation to the new technologies introduced. (author). 86 refs., 40 figs., 14 tabs.

Monte Carlo derivation of filtered tungsten anode X-ray spectra for dose computation in digital mammography

Energy Technology Data Exchange (ETDEWEB)

Paixao, L.; Oliveira, B. B.; Nogueira, M. do S. [Centro de Desenvolvimento da Tecnologia Nuclear, Post-graduation in Science and Technology of Radiations, Minerals and Materials, Pte. Antonio Carlos 6.627, Pampulha, 31270-901 Belo Horizonte (Brazil); Viloria, C. [UFMG, Departamento de Engenharia Nuclear, Post-graduation in Nuclear Sciences and Techniques, Pte. Antonio Carlos 6.627, Pampulha, 31270-901 Belo Horizonte (Brazil); Alves de O, M. [UFMG, Department of Anatomy and Imaging, Prof. Alfredo Balena 190, 30130-100 Belo Horizonte (Brazil); Araujo T, M. H., E-mail: lpr@cdtn.br [Dr Maria Helena Araujo Teixeira Clinic, Guajajaras 40, 30180-100 Belo Horizonte (Brazil)

2014-08-15

It is widely accepted that the mean glandular dose (D{sub G}) for the glandular tissue is the more useful magnitude for characterizing the breast cancer risk. The procedure to estimate the D{sub G}, for being difficult to measure it directly in the breast, it is to make the use of conversion factors that relate incident air kerma (K{sub i}) at this dose. Generally, the conversion factors vary with the x-ray spectrum half-value layer and the breast composition and thickness. Several authors through computer simulations have calculated such factors by the Monte Carlo (Mc) method. Many spectral models for D{sub G} computer simulations purposes are available in the diagnostic range. One of the models available generates unfiltered spectra. In this work, the Monte Carlo EGSnrc code package with the C++ class library (eg spp) was employed to derive filtered tungsten x-ray spectra used in digital mammography systems. Filtered spectra for rhodium and aluminium filters were obtained for tube potentials between 26 and 32 kV. The half-value layer of simulated filtered spectra were compared with those obtained experimentally with a solid state detector Unfors model 8202031-H Xi R/F and Mam Detector Platinum and 8201023-C Xi Base unit Platinum Plus w m As in a Hologic Selenia Dimensions system using a Direct Radiography mode. Calculated half-value layer values showed good agreement compared to those obtained experimentally. These results show that the filtered tungsten anode x-ray spectra and the EGSnrc Mc code can be used for D{sub G} determination in mammography. (Author)

Monte Carlo derivation of filtered tungsten anode X-ray spectra for dose computation in digital mammography

International Nuclear Information System (INIS)

Paixao, L.; Oliveira, B. B.; Nogueira, M. do S.; Viloria, C.; Alves de O, M.; Araujo T, M. H.

2014-08-01

It is widely accepted that the mean glandular dose (D G ) for the glandular tissue is the more useful magnitude for characterizing the breast cancer risk. The procedure to estimate the D G , for being difficult to measure it directly in the breast, it is to make the use of conversion factors that relate incident air kerma (K i ) at this dose. Generally, the conversion factors vary with the x-ray spectrum half-value layer and the breast composition and thickness. Several authors through computer simulations have calculated such factors by the Monte Carlo (Mc) method. Many spectral models for D G computer simulations purposes are available in the diagnostic range. One of the models available generates unfiltered spectra. In this work, the Monte Carlo EGSnrc code package with the C++ class library (eg spp) was employed to derive filtered tungsten x-ray spectra used in digital mammography systems. Filtered spectra for rhodium and aluminium filters were obtained for tube potentials between 26 and 32 kV. The half-value layer of simulated filtered spectra were compared with those obtained experimentally with a solid state detector Unfors model 8202031-H Xi R/F and Mam Detector Platinum and 8201023-C Xi Base unit Platinum Plus w m As in a Hologic Selenia Dimensions system using a Direct Radiography mode. Calculated half-value layer values showed good agreement compared to those obtained experimentally. These results show that the filtered tungsten anode x-ray spectra and the EGSnrc Mc code can be used for D G determination in mammography. (Author)

Investigation of absorbed radiation dose in refraction-enhanced breast tomosynthesis by a Laue case analyser

International Nuclear Information System (INIS)

Sato, H.; Ando, M.; Shimao, D.

2011-01-01

An early diagnosis system for breast cancer using refraction-enhanced breast tomosynthesis is under development. Tomograms of breast specimens based on refraction-contrast were demonstrated using the simplest shift-and-add tomosynthesis algorithm. Raw projection image data of breast specimens for tomosynthesis were acquired for a total of 51 views over an angle of 50 deg., in increments of 1 deg., by rotating the object. The incident X ray was monochromatic synchrotron radiation with 20 keV. The purpose of this study was to estimate the absorbed dose of a new X-ray imaging method. As breast cancer almost always arises in glandular breast tissue, the average absorbed dose in such glandular tissue should be measured to estimate the radiation risk associated with mammography. The absorbed dose of the mammary gland due to monochromatic X rays was calculated by the Monte Carlo method, and the optimal X ray energy range for refraction-enhanced breast tomosynthesis was investigated through actual measurements. Compared with the conventional method, it was found to be below one-sixth per inspection. (authors)

CINtec PLUS immunocytochemistry as a tool for the cytologic diagnosis of glandular lesions of the cervix uteri.

Science.gov (United States)

Ravarino, Alberto; Nemolato, Sonia; Macciocu, Elena; Fraschini, Matteo; Senes, Giancarlo; Faa, Gavino; Negri, Giovanni

2012-11-01

Cytologic findings of glandular lesions of the cervix uteri are often difficult to evaluate. We studied the usefulness of CINtec PLUS p16/Ki-67 double stain (mtm laboratories, Heidelberg, Germany) for the diagnosis of glandular lesions. The study included 47 abnormal results on liquid-based cytologic tests with a subsequent histologic diagnosis of adenocarcinoma in situ or with early invasion, and 16 samples with negative results on follow-up. All samples were stained with CINtec PLUS p16/Ki-67 double stain. Of the neoplastic samples, 7 were excluded because of insufficient residual cellularity or loss of neoplastic cells. Of the samples that were adequate, 92.5% were stained with CINtec PLUS, whereas 7.5% were judged inconclusive. All inconclusive cases were at least 3 years old. Of the 16 negative samples, 15 (93.8%) stained negative and only 1 (6.2%) showed several positive clusters of cells. Our study shows that CINtec PLUS is a robust and useful tool for the diagnosis of glandular lesions of the cervix uteri.

Cloning of a sesquiterpene synthase from Lavandula x intermedia glandular trichomes.

Science.gov (United States)

Sarker, Lukman S; Demissie, Zerihun A; Mahmoud, Soheil S

2013-11-01

The essential oil (EO) of Lavandula is dominated by monoterpenes, but can also contain small amounts of sesquiterpenes, depending on species and environmental conditions. For example, the sesquiterpene 9-epi-caryophyllene can make up to 8 % of the EO in a few species, including those commercially propagated for EO production. Here, we report the cloning and functional characterization of 9-epi-caryophyllene synthase (LiCPS) from the glandular trichomes of Lavandula x intermedia, cv. Grosso. The 1,617 bp open reading frame of LiCPS, which did not encode a transit peptide, was expressed in Escherichia coli and the recombinant protein purified by Ni-NTA agarose affinity chromatography. The ca. 60 kDa recombinant protein specifically converted farnesyl diphosphate to 9-epi-caryophyllene. LiCPS also produced a few monoterpenes when assayed with the monoterpene precursor geranyl diphosphate (GPP), but--unlike most monoterpene synthases--was not able to derive detectable amounts of any products from the cis isomer of GPP, neryl diphosphate. The LiCPS transcripts accumulated in developing L. x intermedia flowers and were highly enriched in glandular trichomes, but were not detected in leaves suggesting that the transcriptional expression of this gene is spatially and developmentally regulated.

A novel dose uncertainty model and its application for dose verification

International Nuclear Information System (INIS)

Jin Hosang; Chung Heetaek; Liu Chihray; Palta, Jatinder; Suh, Tae-Suk; Kim, Siyong

2005-01-01

Based on statistical approach, a novel dose uncertainty model was introduced considering both nonspatial and spatial dose deviations. Non-space-oriented uncertainty is mainly caused by dosimetric uncertainties, and space-oriented dose uncertainty is the uncertainty caused by all spatial displacements. Assuming these two parts are independent, dose difference between measurement and calculation is a linear combination of nonspatial and spatial dose uncertainties. Two assumptions were made: (1) the relative standard deviation of nonspatial dose uncertainty is inversely proportional to the dose standard deviation σ, and (2) the spatial dose uncertainty is proportional to the gradient of dose. The total dose uncertainty is a quadratic sum of the nonspatial and spatial uncertainties. The uncertainty model provides the tolerance dose bound for comparison between calculation and measurement. In the statistical uncertainty model based on a Gaussian distribution, a confidence level of 3σ theoretically confines 99.74% of measurements within the bound. By setting the confidence limit, the tolerance bound for dose comparison can be made analogous to that of existing dose comparison methods (e.g., a composite distribution analysis, a γ test, a χ evaluation, and a normalized agreement test method). However, the model considers the inherent dose uncertainty characteristics of the test points by taking into account the space-specific history of dose accumulation, while the previous methods apply a single tolerance criterion to the points, although dose uncertainty at each point is significantly different from others. Three types of one-dimensional test dose distributions (a single large field, a composite flat field made by two identical beams, and three-beam intensity-modulated fields) were made to verify the robustness of the model. For each test distribution, the dose bound predicted by the uncertainty model was compared with simulated measurements. The simulated

Evaluation of repeated dose micronucleus assays of the liver and gastrointestinal tract using potassium bromate: a report of the collaborative study by CSGMT/JEMS.MMS.

Science.gov (United States)

Okada, Emiko; Fujiishi, Yohei; Narumi, Kazunori; Kado, Shoichi; Wako, Yumi; Kawasako, Kazufumi; Kaneko, Kimiyuki; Ohyama, Wakako

2015-03-01

The food additive potassium bromate (KBrO3) is known as a renal carcinogen and causes chromosomal aberrations in vitro without metabolic activation and in vivo in hematopoietic and renal cells. As a part of a collaborative study by the Mammalian Mutagenicity Study group, which is a subgroup of the Japanese Environmental Mutagen Society, we administered KBrO3 to rats orally for 4, 14, and 28 days and examined the micronucleated (MNed) cell frequency in the liver, glandular stomach, colon, and bone marrow to confirm whether the genotoxic carcinogen targeting other than liver and gastrointestinal (GI) tract was detected by the repeated dose liver and GI tract micronucleus (MN) assays. In our study, animals treated with KBrO3 showed some signs of toxicity in the kidney and/or stomach. KBrO3 did not increase the frequency of MNed cells in the liver and colon in any of the repeated dose studies. However, KBrO3 increased the frequency of MNed cells in the glandular stomach and bone marrow. Additionally, the MNed cell frequency in the glandular stomach was not significantly affected by the difference in the length of the administration period. These results suggest that performing the MN assay using the glandular stomach, which is the first tissue to contact agents after oral ingestion, is useful for evaluating the genotoxic potential of chemicals and that the glandular stomach MN assay could be integrated into general toxicity studies. Copyright © 2014 Elsevier B.V. All rights reserved.

Diagnostic and therapeutic dilemma associated with atypical glandular cells on liquid-based cervical cytology.

LENUS (Irish Health Repository)

Chummun, K

2012-12-01

In 2008, the management of women in Ireland with atypical glandular cells changed to immediate referral to colposcopy. The optimal management of these women is unclear. A balance between the detection of occult disease and overtreatment is required.

Botulinum toxin for treatment of glandular hypersecretory disorders.

LENUS (Irish Health Repository)

Laing, T A

2012-02-03

SUMMARY: The use of botulinum toxin to treat disorders of the salivary glands is increasing in popularity in recent years. Recent reports of the use of botulinum toxin in glandular hypersecretion suggest overall favourable results with minimal side-effects. However, few randomised clinical trials means that data are limited with respect to candidate suitability, treatment dosages, frequency and duration of treatment. We report a selection of such cases from our own department managed with botulinum toxin and review the current data on use of the toxin to treat salivary gland disorders such as Frey\\'s syndrome, excessive salivation (sialorrhoea), focal and general hyperhidrosis, excessive lacrimation and chronic rhinitis.

Experimental data and dose-response models

International Nuclear Information System (INIS)

Ullrich, R.L.

1985-01-01

Dose-response relationships for radiation carcinogenesis have been of interest to biologists, modelers, and statisticians for many years. Despite his interest there are few instances in which there are sufficient experimental data to allow the fitting of various dose-response models. In those experimental systems for which data are available the dose-response curves for tumor induction for the various systems cannot be described by a single model. Dose-response models which have been observed following acute exposures to gamma rays include threshold, quadratic, and linear models. Data on sex, age, and environmental influences of dose suggest a strong role of host factors on the dose response. With decreasing dose rate the effectiveness of gamma ray irradiation tends to decrease in essentially every instance. In those cases in which the high dose rate dose response could be described by a quadratic model, the effect of dose rate is consistent with predictions based on radiation effects on the induction of initial events. Whether the underlying reasons for the observed dose-rate effect is a result of effects on the induction of initial events or is due to effects on the subsequent steps in the carcinogenic process is unknown. Information on the dose response for tumor induction for high LET (linear energy transfer) radiations such as neutrons is even more limited. The observed dose and dose rate data for tumor induction following neutron exposure are complex and do not appear to be consistent with predictions based on models for the induction of initial events

Long acting β2-agonist and corticosteroid restore airway glandular cell function altered by bacterial supernatant

Directory of Open Access Journals (Sweden)

Nawrocki-Raby Béatrice

2010-01-01

Full Text Available Abstract Background Staphylococcus aureus releases virulence factors (VF that may impair the innate protective functions of airway cells. The aim of this study was to determine whether a long-acting β2 adrenergic receptor agonist (salmeterol hydroxynaphthoate, Sal combined with a corticosteroid (fluticasone propionate, FP was able to regulate ion content and cytokine expression by airway glandular cells after exposure to S. aureus supernatant. Methods A human airway glandular cell line was incubated with S. aureus supernatant for 1 h and then treated with the combination Sal/FP for 4 h. The expression of actin and CFTR proteins was analyzed by immunofluorescence. Videomicroscopy was used to evaluate chloride secretion and X-ray microanalysis to measure the intracellular ion and water content. The pro-inflammatory cytokine expression was assessed by RT-PCR and ELISA. Results When the cells were incubated with S. aureus supernatant and then with Sal/FP, the cellular localisation of CFTR was apical compared to the cytoplasmic localisation in cells incubated with S. aureus supernatant alone. The incubation of airway epithelial cells with S. aureus supernatant reduced by 66% the chloride efflux that was fully restored by Sal/FP treatment. We also observed that Sal/FP treatment induced the restoration of ion (Cl and S and water content within the intracellular secretory granules of airway glandular cells and reduced the bacterial supernatant-dependent increase of pro-inflammatory cytokines IL8 and TNFα. Conclusions Our results demonstrate that treatment with the combination of a corticosteroid and a long-acting β2 adrenergic receptor agonist after bacterial infection restores the airway glandular cell function. Abnormal mucus induced by defective ion transport during pulmonary infection could benefit from treatment with a combination of β2 adrenergic receptor agonist and glucocorticoid.

Glandular trichome density and essential oil composition in leaves and inflorescences of Lippia origanoides Kunth (Verbenaceae in the Brazilian Cerrado

Directory of Open Access Journals (Sweden)

Luiz R.S. Tozin

2015-06-01

Full Text Available The essential oils from leaves and inflorescences of Lippia origanoides Kunth present aromatic and medicinal potential and have been used to treat several diseases, including melanoma. In Brazil, L. origanoides is commonly found in campo cerrado and cerrado stricto sensu, physiognomies featured mainly by the differential light conditions to which short and medium-sized plants are subjected. Our aim was to investigate the glandular trichome density and the yield and chemical composition of the essential oils in leaves and inflorescences of L. origanoides from campo cerrado and cerrado stricto sensu. For glandular density analysis, leaves and inflorescences were processed according to conventional techniques for scanning electron microscopy. The essential oils of leaves and inflorescences were obtained by hydrodistillation and identified with gas chromatography. Bracts and sepals showed the highest glandular density, followed by petals and leaves. The glandular density in the abaxial leaf surface was higher in individuals from the campo cerrado. In both populations the essential oil yield was higher in inflorescences than in leaves. The chemical composition of the essential oils varied among individuals from different areas and inside a same population. Our results demonstrated the chemical plasticity of L. origanoides suggesting the importance of monitoring its popular use.

Glandular trichome density and essential oil composition in leaves and inflorescences of Lippia origanoides Kunth (Verbenaceae) in the Brazilian Cerrado.

Science.gov (United States)

Tozin, Luiz R S; Marques, Marcia O M; Rodrigues, Tatiane M

2015-01-01

The essential oils from leaves and inflorescences of Lippia origanoides Kunth present aromatic and medicinal potential and have been used to treat several diseases, including melanoma. In Brazil, L. origanoides is commonly found in campo cerrado and cerrado stricto sensu, physiognomies featured mainly by the differential light conditions to which short and medium-sized plants are subjected. Our aim was to investigate the glandular trichome density and the yield and chemical composition of the essential oils in leaves and inflorescences of L. origanoides from campo cerrado and cerrado stricto sensu. For glandular density analysis, leaves and inflorescences were processed according to conventional techniques for scanning electron microscopy. The essential oils of leaves and inflorescences were obtained by hydrodistillation and identified with gas chromatography. Bracts and sepals showed the highest glandular density, followed by petals and leaves. The glandular density in the abaxial leaf surface was higher in individuals from the campo cerrado. In both populations the essential oil yield was higher in inflorescences than in leaves. The chemical composition of the essential oils varied among individuals from different areas and inside a same population. Our results demonstrated the chemical plasticity of L. origanoides suggesting the importance of monitoring its popular use.

Genetic Architecture of Capitate Glandular Trichome Density in Florets of Domesticated Sunflower (Helianthus annuus L.).

Science.gov (United States)

Gao, Qing-Ming; Kane, Nolan C; Hulke, Brent S; Reinert, Stephan; Pogoda, Cloe S; Tittes, Silas; Prasifka, Jarrad R

2017-01-01

Capitate glandular trichomes (CGT), one type of glandular trichomes, are most common in Asteraceae species. CGT can produce various secondary metabolites such as sesquiterpene lactones (STLs) and provide durable resistance to insect pests. In sunflower, CGT-based host resistance is effective to combat the specialist pest, sunflower moth. However, the genetic basis of CGT density is not well understood in sunflower. In this study, we identified two major QTL controlling CGT density in sunflower florets by using a F 4 mapping population derived from the cross HA 300 × RHA 464 with a genetic linkage map constructed from genotyping-by-sequencing data and composed of 2121 SNP markers. One major QTL is located on chromosome 5, which explained 11.61% of the observed phenotypic variation, and the second QTL is located on chromosome 6, which explained 14.06% of the observed phenotypic variation. The QTL effects and the association between CGT density and QTL support interval were confirmed in a validation population which included 39 sunflower inbred lines with diverse genetic backgrounds. We also identified two strong candidate genes in the QTL support intervals, and the functions of their orthologs in other plant species suggested their potential roles in regulating capitate glandular trichome density in sunflower. Our results provide valuable information to sunflower breeding community for developing host resistance to sunflower insect pests.

Patient dose in digital mammography

International Nuclear Information System (INIS)

Chevalier, Margarita; Moran, Pilar; Ten, Jose I.; Fernandez Soto, Jose M.; Cepeda, T.; Vano, Eliseo

2004-01-01

In the present investigation, we analyze the dose of 5034 patients (20 137 images) who underwent mammographic examinations with a full-field digital mammography system. Also, we evaluate the system calibration by analyzing the exposure factors as a function of breast thickness. The information relevant to this study has been extracted from the image DICOM header and stored in a database during a 3-year period (March 2001-October 2003). Patient data included age, breast thickness, kVp, mAs, target/filter combination, and nominal dose values. Entrance surface air kerma (ESAK) without backscatter was calculated from the tube output as measured for each voltage used under clinical conditions and from the tube loading (mAs) included in the DICOM header. Mean values for the patient age and compressed breast thickness were 56 years (SD: 11) and 52 mm (SD: 13), respectively. The majority of the images was acquired using the STD (for standard) automatic mode (98%). The most frequent target/filter combination automatically selected for breast smaller than 35 mm was Mo/Mo (75%); for intermediate thicknesses between 35 and 65 mm, the combinations were Mo/Rh (54%) and Rh/Rh (38.5%); Rh/Rh was the combination selected for 91% of the cases for breasts thicker than 65 mm. A wide kVp range was observed for each target/filter combination. The most frequent values were 28 kVp for Mo/Mo, 29 kVp for Mo/Rh, and 29 and 30 kV for Rh/Rh. Exposure times ranged from 0.2 to 4.2 s with a mean value of 1.1 s. Average glandular doses (AGD) per exposure were calculated by multiplying the ESAK values by the conversion factors tabulated by Dance for women in the age groups 50 to 64 and 40 to 49. This approach is based on the dependence of breast glandularity on breast thickness and age. The total mean average glandular dose (AGD T ) was calculated by summing the values associated with the pre-exposure and with the main exposure. Mean AGD T per exposure was 1.88 mGy (CI 0.01) and the mean AGD T per

Elimination of salmonella from animal glandular products.

Science.gov (United States)

De Fiebre, C W; Burck, K T; Feldman, D

1969-03-01

Methods for the elimination of salmonellae from selected powdered pharmaceuticals of animal glandular origin were studied. Terminal heat treatment under carefully controlled conditions was effective for pancreatin-a powder containing proteolytic, amylolytic, and lipolytic enzymes prepared from hog pancreas glands. Use of this method resulted in a significant reduction in the number of salmonella-positive batches and also reduced the testing procedures required to confirm the absence of viable salmonellae among the majority of samples tested. Powders such as stomach substance and thyroid, in which the biological activity is not enzyme in nature, were treated successfully with acidified organic solvents. Other methods were investigated but were not suitable because of a deleterious effect on the biological activity or physical properties of the product or an inability to effect salmonella elimination.

Elimination of Salmonellae from Animal Glandular Products

Science.gov (United States)

De Fiebre, Conrad W.; Burck, Kenneth T.; Feldman, David

1969-01-01

Methods for the elimination of salmonellae from selected powdered pharmaceuticals of animal glandular origin were studied. Terminal heat treatment under carefully controlled conditions was effective for pancreatin—a powder containing proteolytic, amylolytic, and lipolytic enzymes prepared from hog pancreas glands. Use of this method resulted in a significant reduction in the number of salmonella-positive batches and also reduced the testing procedures required to confirm the absence of viable salmonellae among the majority of samples tested. Powders such as stomach substance and thyroid, in which the biological activity is not enzyme in nature, were treated successfully with acidified organic solvents. Other methods were investigated but were not suitable because of a deleterious effect on the biological activity or physical properties of the product or an inability to effect salmonella elimination. PMID:5780395

Comparison of Nordic dose models

International Nuclear Information System (INIS)

Thykier-Nielsen, S.

1978-04-01

A comparison is made between the models used in the four Nordic countries, Finland, Norway, Sweden and Denmark, for calculation of concentrations and doses from releases of radioactive material to the atmosphere. The comparison is limited to the near-zone models, i.e. the models for calculation of concentrations and doses within 50 km from the release point, and it comprises the following types of calculation: a. Concentrations of airborne material, b. External gamma doses from a plume, c. External gamma doses from radioactive material deposited on the ground. All models are based on the gaussian dispersion model (the gaussian plume model). Unit releases of specific isotopes under specific meteorological conditions are assumed. On the basis of the calculation results from the models, it is concluded that there are no essential differences. The difference between the calculation results only exceeds a factor of 3 in special cases. It thus lies within the known limits of uncertainty for the gaussian plume model. (author)

Glandular differentiation in dedifferentiated chondrosarcoma: molecular evidence of a rare phenomenon.

Science.gov (United States)

Jour, George; Liu, Yajuan; Ricciotti, Robert; Pritchard, Colin; Hoch, Benjamin L

2015-09-01

Epithelial glandular differentiation in dedifferentiated chondrosarcoma has not been described. Our patient was a 64-year-old man with a history of prostate cancer status post-radiation and hormonal therapy. On screening bone scan, he was found to have increased uptake in his right femoral shaft. Biopsy revealed intermediate-grade conventional chondrosarcoma. Subsequent femoral resection was remarkable for an intermediate-grade chondrosarcomatous component juxtaposed to an area composed of anastomosing nests and cords of malignant epithelial cells showing nuclear atypia and increased mitotic activity. A fibroblastic-appearing spindle cell population was intimately associated with the epithelial cells. The epithelial cells labeled with 34bE12, AE1/AE3, EMA, and Vimentin (both spindled and epithelial components) while being negative for prostate-specific antigen, prostate specific acid phosphatase, cytokeratin 20, thyroid transcription factor-1, and CDX2. The patient developed local recurrence 9 months after the initial resection but has had no metastatic disease and consistently undetectable prostate-specific antigen levels. Deep parallel sequencing of the dedifferentiated component showed a nonsynonymous mutation at exon 4 of IDH1 gene at codon R132 leading to a substitution of arginine, with serine confirming glandular differentiation in dedifferentiated chondrosarcoma. Copyright © 2015 Elsevier Inc. All rights reserved.

Optimum filter selection for Dual Energy X-ray Applications through Analytical Modeling

International Nuclear Information System (INIS)

Koukou, V; Martini, N; Sotiropoulou, P; Nikiforidis, G; Michail, C; Kalyvas, N; Kandarakis, I; Fountos, G

2015-01-01

In this simulation study, an analytical model was used in order to determine the optimal acquisition parameters for a dual energy breast imaging system. The modeled detector system, consisted of a 33.91mg/cm 2 Gd 2 O 2 S:Tb scintillator screen, placed in direct contact with a high resolution CMOS sensor. Tungsten anode X-ray spectra, filtered with various filter materials and filter thicknesses were examined for both the low- and high-energy beams, resulting in 3375 combinations. The selection of these filters was based on their K absorption edge (K-edge filtering). The calcification signal-to-noise ratio (SNR tc ) and the mean glandular dose (MGD) were calculated. The total mean glandular dose was constrained to be within acceptable levels. Optimization was based on the maximization of the SNR tc /MGD ratio. The results showed that the optimum spectral combination was 40kVp with added beam filtration of 100 μm Ag and 70kVp Cu filtered spectrum of 1000 μm for the low- and high-energy, respectively. The minimum detectable calcification size was 150 μm. Simulations demonstrate that this dual energy X-ray technique could enhance breast calcification detection. (paper)

[Treatment of gynecomastia by a combined method of liposuction and semicircular periareolar incision glandular organ partial resection].

Science.gov (United States)

Liu, Su; Kuang, Ruixia; Chen, Zhenyu; Li, Huichao; Zhang, Weina; Wang, Zhiguo; Miao, Yuanxin; Chen, Lu

2008-12-01

To evaluate the effect of the combined method of liposuction and semicircular periareolar incision glandular organ partial resection in the treatment of gynecomastia. From June 2004 to June 2006, 40 patients, aged 11-41 years old, were treated, with no-nodule (n = 10), nodule (n = 22) and female-breast-like with nodules (n = 8). Three patients were unilateral and 37 ones were bilateral. The levels of serum prolactin, luteinizing hormone, follicle stimulating hormone, estradiol, testosterone and cortisol were normal in 38 patients, while in the other 2 patients, the levels of serum prolactin, luteinizing hormone, follicle stimulating hormone and estradiol were higher than normal, and the testosterone level was lower. Liposuction alone was performed in 10 no-nodule patients (lipo-type), and combined liposuction and semicircular periareolar incision glandular organ partial resection were conducted in the other 30 patients (lipo-glandular type). RESULTS; Except for 2 cases in which hematoma and a small amount of effusion were found on the first and second day postoperatively and then obtained healing by first intention right after hematoma removal in time, all the other patients incisions obtained healing by first intention. Nipple numbness occurred in 3 cases on the first day postoperatively and no special treatment was conducted. There was still nipple hypesthesia in these 3 cases after 6-month follow-up. There were no complications such as hematoma, effusion, nipple and mammary areola necrosis, and nipple hypesthesia in other patients. All the 40 patients were followed up for 6-24 months (13 months on average). They were satisfied with their chest figures and no recurrence was observed. The combined method of liposuction and semicircular periareolar incision glandular organ partial resection in the treatment of gynecomastia has many advantages, such as safe, micro-scars, natural and beautiflhl male breast figures as well as high patients' satisfaction.

Radiation dose with digital breast tomosynthesis compared to digital mammography: per-view analysis.

Science.gov (United States)

Gennaro, Gisella; Bernardi, D; Houssami, N

2018-02-01

To compare radiation dose delivered by digital mammography (FFDM) and breast tomosynthesis (DBT) for a single view. 4,780 FFDM and 4,798 DBT images from 1,208 women enrolled in a screening trial were used to ground dose comparison. Raw images were processed by an automatic software to determine volumetric breast density (VBD) and were used together with exposure data to compute the mean glandular dose (MGD) according to Dance's model. DBT and FFDM were compared in terms of operation of the automatic exposure control (AEC) and MGD level. Statistically significant differences were found between FFDM and DBT MGDs for all views (CC: MGD FFDM =1.366 mGy, MGD DBT =1.858 mGy; ptomosynthesis compared to FFDM. Given the emerging role of DBT, its use in conjunction with synthetic 2D images should not be deterred by concerns regarding radiation burden, and should draw on evidence of potential clinical benefit. • Most studies compared tomosynthesis in combination with mammography vs. mammography alone. • There is some concern about the dose increase with tomosynthesis. • Clinical data show a small increase in radiation dose with tomosynthesis. • Synthetic 2D images from tomosynthesis at zero dose reduce potential harm. • The small dose increase should not be a barrier to use of tomosynthesis.

Gynecomastia: glandular-liposculpture through a single transaxillary one hole incision.

Science.gov (United States)

Lee, Yung Ki; Lee, Jun Hee; Kang, Sang Yoon

2018-04-01

Gynecomastia is characterized by the benign proliferation of breast tissue in men. Herein, we present a new method for the treatment of gynecomastia, using ultrasound-assisted liposuction with both conventional and reverse-cutting edge tip cannulas in combination with a pull-through lipectomy technique with pituitary forceps through a single transaxillary incision. Thirty patients were treated with this technique at the author's institution from January 2010 to January 2015. Ten patients were treated with conventional surgical excision of the glandular/fibrous breast tissue combined with liposuction through a periareolar incision before January 2010. Medical records, clinical photographs and linear analog scale scores were analyzed to compare the surgical results and complications. The patients were required to rate their cosmetic outcomes based on the linear analog scale with which they rated their own surgical results; the mean overall average score indicated a good or high level of satisfaction. There were no incidences of skin necrosis, hematoma, infection and scar contracture; however, one case each of seroma and nipple inversion did occur. Operative time was reduced overall using the new technique since it is relatively simple and straightforward. According to the evaluation by the four independent researchers, the patients treated with this new technique showed statistically significant improvements in scar and nipple-areolar complex (NAC) deformity compared to those who were treated using the conventional method. Glandular liposculpture through a single transaxillary incision is an efficient and safe technique that can provide aesthetically satisfying and consistent results.

Thyroid absorbed dose using TLDs during mammography

International Nuclear Information System (INIS)

Gonzalez A, M.; Melendez L, M.; Davila M, P.

2015-10-01

Full text: In this study, the mean glandular dose (MGD) and the thyroid dose (D Thy) were measured in 200 women screened with mammography in Cranio caudal (Cc) and mediolateral oblique projections. All mammograms were performed with Giotto-Ims (6000-14-M2 Model) equipment, which was verified to meet the criteria of quality of NOM-229-Ssa-2002. During audits performance and HVL, for each anode filter combinations was measured with the camera Radcal mammography equipment 10 X 6-6M (HVL = 0.26 mm Al). D Thy measurements were performed with TLD dosimeters (LiF:Mn) , that were read with the Harshaw 3500 TLD reader. The MGD, was obtained according to the UK and European protocols for mammographic dosimetry using a plane parallel chamber (Standard Imaging, Model A-600) calibrated by a radiation beam UW-23-Mo (= 0.279 mm Al HVL). A comparative statistical analysis was carried out with the measured MGD and D thy. The thyroid mean dose was 0.063 mGy and 0.078 mGy for Cc and mediolateral oblique respectively. There is a linear correlation between the MGD and the D Thy slightly influenced by the anode-filter combination. Using a 95% for the confidence interval in MGD (1.07 mGy), the 90% of measurements are in agreement with the established uncertainty limits. The D Thy are lower than the MGD. There is no risk for cancer induction in thyroid in women due to mammography screening. (Author)

Capitate glandular trichomes in Aldama discolor (Heliantheae - Asteraceae): morphology, metabolite profile and sesquiterpene biosynthesis.

Science.gov (United States)

Bombo, A B; Appezzato-da-Glória, B; Aschenbrenner, A-K; Spring, O

2016-05-01

The capitate glandular trichome is the most common type described in Asteraceae species. It is known for its ability to produce various plant metabolites of ecological and economic importance, among which sesquiterpene lactones are predominant. In this paper, we applied microscopy, phytochemical and molecular genetics techniques to characterise the capitate glandular trichome in Aldama discolor, a native Brazilian species of Asteraceae, with pharmacological potential. It was found that formation of trichomes on leaf primordia of germinating seeds starts between 24 h and 48 h after radicle growth indicates germination. The start of metabolic activity of trichomes was indicated by separation of the cuticle from the cell wall of secretory cells at the trichome tip after 72 h. This coincided with the accumulation of budlein A, the major sesquiterpene lactone of A. discolor capitate glandular trichomes, in extracts of leaf primordia after 96 h. In the same timeframe of 72-96 h post-germination, gene expression studies showed up-regulation of the putative germacrene A synthase (pGAS2) and putative germacrene A oxidase (pGAO) of A. discolor in the transcriptome of these samples, indicating the start of sesquiterpene lactone biosynthesis. Sequencing of the two genes revealed high similarity to HaGAS and HaGAO from sunflower, which shows that key steps of this pathway are highly conserved. The processes of trichome differentiation, metabolic activity and genetic regulation in A. discolor and in sunflower appear to be typical for other species of the subtribe Helianthinae. © 2015 German Botanical Society and The Royal Botanical Society of the Netherlands.

Comparative evaluation of average glandular dose and breast cancer detection between single-view digital breast tomosynthesis (DBT) plus single-view digital mammography (DM) and two-view DM: correlation with breast thickness and density

International Nuclear Information System (INIS)

Shin, Sung Ui; Chang, Jung Min; Bae, Min Sun; Lee, Su Hyun; Cho, Nariya; Seo, Mirinae; Kim, Won Hwa; Moon, Woo Kyung

2015-01-01

To compare the average glandular dose (AGD) and diagnostic performance of mediolateral oblique (MLO) digital breast tomosynthesis (DBT) plus cranio-caudal (CC) digital mammography (DM) with two-view DM, and to evaluate the correlation of AGD with breast thickness and density. MLO and CC DM and DBT images of both breasts were obtained in 149 subjects. AGDs of DBT and DM per exposure were recorded, and their correlation with breast thickness and density were evaluated. Paired data of MLO DBT plus CC DM and two-view DM were reviewed for presence of malignancy in a jack-knife alternative free-response ROC (JAFROC) method. The AGDs of both DBT and DM, and differences in AGD between DBT and DM (ΔAGD), were correlated with breast thickness and density. The average JAFROC figure of merit (FOM) was significantly higher on the combined technique than two-view DM (P = 0.005). In dense breasts, the FOM and sensitivity of the combined technique was higher than that of two-view DM (P = 0.003) with small ΔAGD. MLO DBT plus CC DM provided higher diagnostic performance than two-view DM in dense breasts with a small increase in AGD. (orig.)

Comparative evaluation of average glandular dose and breast cancer detection between single-view digital breast tomosynthesis (DBT) plus single-view digital mammography (DM) and two-view DM: correlation with breast thickness and density

Energy Technology Data Exchange (ETDEWEB)

Shin, Sung Ui; Chang, Jung Min; Bae, Min Sun; Lee, Su Hyun; Cho, Nariya; Seo, Mirinae; Kim, Won Hwa; Moon, Woo Kyung [Seoul National University Hospital, Department of Radiology, Seoul (Korea, Republic of)

2015-01-15

To compare the average glandular dose (AGD) and diagnostic performance of mediolateral oblique (MLO) digital breast tomosynthesis (DBT) plus cranio-caudal (CC) digital mammography (DM) with two-view DM, and to evaluate the correlation of AGD with breast thickness and density. MLO and CC DM and DBT images of both breasts were obtained in 149 subjects. AGDs of DBT and DM per exposure were recorded, and their correlation with breast thickness and density were evaluated. Paired data of MLO DBT plus CC DM and two-view DM were reviewed for presence of malignancy in a jack-knife alternative free-response ROC (JAFROC) method. The AGDs of both DBT and DM, and differences in AGD between DBT and DM (ΔAGD), were correlated with breast thickness and density. The average JAFROC figure of merit (FOM) was significantly higher on the combined technique than two-view DM (P = 0.005). In dense breasts, the FOM and sensitivity of the combined technique was higher than that of two-view DM (P = 0.003) with small ΔAGD. MLO DBT plus CC DM provided higher diagnostic performance than two-view DM in dense breasts with a small increase in AGD. (orig.)

Dose to population as a metric in the design of optimised exposure control in digital mammography

International Nuclear Information System (INIS)

Klausz, R.; Shramchenko, N.

2005-01-01

This paper describes a methods for automatic optimisation of parameter (AOP) in digital mammography systems. Using a model of the image chain, contrast to noise ratio (CNR) and average glandular dose (AGD) are computed for possible X-ray parameters and breast types. The optimisation process consists of the determination of the operating points providing the lowest possible AGD for each CNR level and breast type. The proposed metric for the dose used in the design of an AOP mode is the resulting dose to the population, computed by averaging the AGD values over the distribution of breast types in the population. This method has been applied to the automatic exposure control of new digital mammography equipment. Breast thickness and composition are estimated from a low dose pre-exposure and used to index tables containing sets of optimised operating points. The resulting average dose to the population ranges from a level comparable to state-of-the-art screen/film mammography to a reduction by a factor of two. Using this method, both CNR and dose are kept under control for all breast types, taking into consideration both individual and collective risk. (authors)

Development and Structure of Internal Glands and External Glandular Trichomes in Pogostemon cablin

Science.gov (United States)

Guo, Jiansheng; Yuan, Yongming; Liu, Zhixue; Zhu, Jian

2013-01-01

Pogostemon cablin possesses two morphologically and ontogenetically different types of glandular trichomes, one type of bristle hair on the surfaces of leaves and stems and one type of internal gland inside the leaves and stems. The internal gland originates from elementary meristem and is associated with the biosynthesis of oils present inside the leaves and stems. However, there is little information on mechanism for the oil biosynthesis and secretion inside the leaves and stems. In this study, we identified three kinds of glandular trichome types and two kinds of internal gland in the Pogostemon cablin. The oil secretions from internal glands of stems and leaves contained lipids, flavones and terpenes. Our results indicated that endoplasmic reticulum and plastids and vacuoles are likely involved in the biosynthesis of oils in the internal glands and the synthesized oils are transported from endoplasmic reticulum to the cell wall via connecting endoplasmic reticulum membranes to the plasma membrane. And the comparative analysis of the development, distribution, histochemistry and ultrastructures of the internal and external glands in Pogostemon cablin leads us to propose that the internal gland may be a novel secretory structure which is different from external glands. PMID:24205002

Fibroblast growth factor 10-fibroblast growth factor receptor 2b mediated signaling is not required for adult glandular stomach homeostasis.

Directory of Open Access Journals (Sweden)

Allison L Speer

Full Text Available The signaling pathways that are essential for gastric organogenesis have been studied in some detail; however, those that regulate the maintenance of the gastric epithelium during adult homeostasis remain unclear. In this study, we investigated the role of Fibroblast growth factor 10 (FGF10 and its main receptor, Fibroblast growth factor receptor 2b (FGFR2b, in adult glandular stomach homeostasis. We first showed that mouse adult glandular stomach expressed Fgf10, its receptors, Fgfr1b and Fgfr2b, and most of the other FGFR2b ligands (Fgf1, Fgf7, Fgf22 except for Fgf3 and Fgf20. Fgf10 expression was mesenchymal whereas FGFR1 and FGFR2 expression were mostly epithelial. Studying double transgenic mice that allow inducible overexpression of Fgf10 in adult mice, we showed that Fgf10 overexpression in normal adult glandular stomach increased epithelial proliferation, drove mucous neck cell differentiation, and reduced parietal and chief cell differentiation. Although a similar phenotype can be associated with the development of metaplasia, we found that Fgf10 overexpression for a short duration does not cause metaplasia. Finally, investigating double transgenic mice that allow the expression of a soluble form of Fgfr2b, FGF10's main receptor, which acts as a dominant negative, we found no significant changes in gastric epithelial proliferation or differentiation in the mutants. Our work provides evidence, for the first time, that the FGF10-FGFR2b signaling pathway is not required for epithelial proliferation and differentiation during adult glandular stomach homeostasis.

The effect of breast compression on mass conspicuity in digital mammography

International Nuclear Information System (INIS)

Saunders, Robert S. Jr; Samei, Ehsan

2008-01-01

This study analyzed how the inherent quality of diagnostic information in digital mammography could be affected by breast compression. A digital mammography system was modeled using a Monte Carlo algorithm based on the Penelope program, which has been successfully used to model several medical imaging systems. First, the Monte Carlo program was validated against previous measurements and simulations. Once validated, the Monte Carlo software modeled a digital mammography system by tracking photons through a voxelized software breast phantom, containing anatomical structures and breast masses, and following photons until they were absorbed by a selenium-based flat-panel detector. Simulations were performed for two compression conditions (standard compression and 12.5% reduced compression) and three photon flux conditions (constant flux, constant detector signal, and constant glandular dose). The results showed that reduced compression led to higher scatter fractions, as expected. For the constant photon flux condition, decreased compression also reduced glandular dose. For constant glandular dose, the SdNR for a 4 cm breast was 0.60±0.11 and 0.62±0.11 under standard and reduced compressions, respectively. For the 6 cm case with constant glandular dose, the SdNR was 0.50±0.11 and 0.49±0.10 under standard and reduced compressions, respectively. The results suggest that if a particular imaging system can handle an approximately 10% increase in total tube output and 10% decrease in detector signal, breast compression can be reduced by about 12% in terms of breast thickness with little impact on image quality or dose.

Ultrastructure of the apical glandular region of the scolex of Proteocephalus torulosus (Cestoda: Proteocephalidae)

Czech Academy of Sciences Publication Activity Database

Žďárská, Zdeňka; Scholz, Tomáš; Nebesářová, Jana

2004-01-01

Roč. 51, č. 4 (2004), s. 333-338 ISSN 0015-5683 R&D Projects: GA ČR GA524/04/0342; GA AV ČR KSK6005114 Institutional research plan: CEZ:AV0Z6022909 Keywords : Cestoda * Proteocephalus torulosus * apical glandular region Subject RIV: GJ - Animal Vermins ; Diseases, Veterinary Medicine Impact factor: 0.837, year: 2004

Total dose and dose rate models for bipolar transistors in circuit simulation.

Energy Technology Data Exchange (ETDEWEB)

Campbell, Phillip Montgomery; Wix, Steven D.

2013-05-01

The objective of this work is to develop a model for total dose effects in bipolar junction transistors for use in circuit simulation. The components of the model are an electrical model of device performance that includes the effects of trapped charge on device behavior, and a model that calculates the trapped charge densities in a specific device structure as a function of radiation dose and dose rate. Simulations based on this model are found to agree well with measurements on a number of devices for which data are available.

An inter-hospital comparison of patient dose based on clinical indications

International Nuclear Information System (INIS)

Teeuwisse, W.; Geleijns, J.; Veldkamp, W.

2007-01-01

Patient dose is usually estimated for a single radiographic projection or computed tomography (CT) series. In this study, patient dose was calculated for predefined clinical indications (24 radiography, 11 CT). Members of the radiology staff of each of 11 hospitals were trained in dose measurement and calculation techniques. Based on clinical indications participants decided on imaging protocols and calculated cumulative effective dose for a complete examination. Effective dose ranged from <1 μSv to 0.6 mSv for examinations with radiographs and from 0.2 to 12 mSv for CT scans. Differences in the imaging protocols contributedd to a substantial variation in patient dose. For mammography, average glandular dose (AGD) was estimated for 32-, 53- and 90-mm compressed breast thicknesses, with a median value of 0.74, 1.74 and 3.40 mGy, respectively. The results presented here demonstrate that a pragmatic choice of dosimetry methods enables local staff to estimate effective dose. The inclusion of imaging protocols in the dose surveys provided a broader view on the variations in patient dose between hospitals. (orig.)

Dose modeling in ultraviolet phototherapy

International Nuclear Information System (INIS)

Grimes, David Robert; Robbins, Chris; O'Hare, Neil John

2010-01-01

Purpose: Ultraviolet phototherapy is widely used in the treatment of numerous skin conditions. This treatment is well established and largely beneficial to patients on both physical and psychological levels; however, overexposure to ultraviolet radiation (UVR) can have detrimental effects, such as erythemal responses and ocular damage in addition to the potentially carcinogenic nature of UVR. For these reasons, it is essential to control and quantify the radiation dose incident upon the patient to ensure that it is both biologically effective and has the minimal possible impact on the surrounding unaffected tissue. Methods: To date, there has been little work on dose modeling, and the output of artificial UVR sources is an area where research has been recommended. This work characterizes these sources by formalizing an approach from first principles and experimentally examining this model. Results: An implementation of a line source model is found to give impressive accuracy and quantifies the output radiation well. Conclusions: This method could potentially serve as a basis for a full computational dose model for quantifying patient dose.

Honey bee males and queens use glandular secretions to enhance sperm viability before and after storage

DEFF Research Database (Denmark)

Den Boer, Susanne Petronella A; Boomsma, Jacobus Jan; Baer, Boris

2009-01-01

Internal fertilization requires live sperm to be transferred from male to female before egg fertilization. Both males and females assist the insemination process by providing sperm with glandular secretions, which have been inferred to contain subsets of proteins that maintain sperm viability. He...

Evolution of the excess absolute risk (EAR) in the Valencian breast cancer screening programme

International Nuclear Information System (INIS)

Ferrer, S.; Ramos, M.; Villaescusa, J. I.; Verdu, G.; Salas, M. D.; Cuevas, M. D.

2004-01-01

Breast cancer is one of the most frequent diseases in women, with a high incidence rate. The best fight against the breast cancer is the early detection by menas of mammograms in a screening programme. The Valencian Breast Cancer Screening Programme (VBCSP) started at 1992, and it is composed of twenty-two mammography units. The programme is targeted towards asympotomatic women dfrom 45 to 69 years old, but this screening has a negative influence in the studied woman, whatever the diagnosis was. By means of MCNP-4c2 Monte Carlo code, some conversion factors from air kerma air kerma to glandular dose have been developed. Different breast woamn models, according to the Valencian brest anathomy (taking into account the relation breast radius / breast compression thickness obtained from real samples, have been simulated in order to obtain the glandular breast dose values. Quality control parameters as ESAK values were also employed for developing the methods. The conversion factors give a simple and fast wasy to obtain the mean glandular dose from mammography exposition parameters. The glandular dose has been also calculated following the European Protocol on Dosimetry in order to compare the results of the new methodology. Four sample populations of 100 omen from each uunit of the VBCSP have been taken innnn order to estimate the mean glandular dose and the associated excess absolute risk (EAR). Once the doses for each woman from the samples are obtained and according to the age of them, the EAR value for each sample has been determinated following the UNSCEAR 2000 projection risk model, which takes into account the characteristics of the Valencian population and gives the EAR for radio-induced breast cancer. The results have been calculated and compared by means of the ASQRAD software, but with an older risk projection model, the UNSCEAR 1994. Once the four sample average EAR have been calculated, the evolution of the induced risk in the Valencian Breast Cancer

Proposal of a probabilistic dose-response model

International Nuclear Information System (INIS)

Barrachina, M.

1997-01-01

A biologically updated dose-response model is presented as an alternative to the linear-quadratic model currently in use for cancer risk assessment. The new model is based on the probability functions for misrepair and/or unrepair of DNA lesions, in terms of the radiation damage production rate in the cell (supposedly, a stem cell) and its repair-rate constant. The model makes use, interpreting it on the basis of misrepair probabilities, of the ''dose and dose-rate effectiveness factor'' of ICRP, and provides the way for a continuous extrapolation between the high and low dose-rate regions, ratifying the ''linear non-threshold hypothesis'' as the main option. Anyhow, the model throws some doubts about the additive property of the dose. (author)

Determination of dose levels for chest (PA), lumbar spine (AP and LAT) and mammography (CC and MLO) for Latin america

International Nuclear Information System (INIS)

Mora, P.; Ramirez, R.; Blanco, D. E.; Benavente, T. A.; Ortiz Lopez, P.; Giannone, C. A.; Gherco, J. T.; Mecca, F.; Kodlulovich, S.; Ramirez, A.; Anselmo Puerta, J. A.; Fonseca, L.; Cardenas, J.; Martinez, A.; Zorin, F. J.; Roas, N.; Garcia, F.; Caldeira, M. E.; Salazar, G.

2006-01-01

Under the auspices of the ARCAL Technical Cooperation Program of the IAEA, 11 countries in Latin American (Argentina, Brazil, Chile, Costa Rica, Cuba, Mexico, Nicaragua, Peru, Uruguay and Venezuela) motivated by the necessity to optimize the doses in diagnostic procedures, started the first regional pilot study to determine the guidance dose levels for chest (PA), lumbar spine (AP and LAT) and mammography (CC and MLO) procedures. A total of 33 hospitals participated with 54 diagnostic X-ray equipment and 18 mammography units. The entrance kerma and mean glandular doses were obtained through the output of the X-rays. A TLD intercomparison was carried out as a means to do quality control of all the process. A total of 2120 doses were estimated with the information of each patient (kVp, mAs, distance, etc.). Parallel to this, the image quality of the studies was evaluated using the criteria established by the European Community. The values of the entrance kerma an mean glandular doses for the 75% percentile are in general very compatible with the ones in Schedule III of the NBS. Although this study did not allow the establishment of guidance levels for the region, it did lay the foundations for optimization processes and the necessity of making better efforts that will improve medical practices. (Author)

Three-dimensional dose distribution in contrast-enhanced digital mammography using Gafchromic XR-QA2 films: Feasibility study

International Nuclear Information System (INIS)

Hwang, Yi-Shuan; Lin, Yu-Ying; Cheung, Yun-Chung; Tsai, Hui-Yu

2014-01-01

This study was aimed to establish three-dimensional dose distributions for contrast-enhanced digital mammography (CEDM) using self-developed Gafchromic XR-QA2 films. Dose calibration and distribution evaluations were performed on a full-field digital mammography unit with dual energy (DE) contrast-enhanced option. Strategy for dose calibration of films in the DE mode was based on the data obtained from common target/filter/kVp combinations used clinically and the dose response model modified from Rampado's model. Dose derived from films were also verified by measured data from an ionization chamber. The average difference of dose was 8.9% in the dose range for clinical uses. Three-dimensional dose distributions were estimated using triangular acrylic phantom equipped with the mammography system. Five pieces of film sheets were separately placed between the acrylic slabs to evaluate the dose distribution at different depths. After normalizing the dose in each pixel to the maximum dose at the top-center position of the acrylic, normalized dose distribution for transverse, coronal and sagittal planes, could thus be obtained. The depth dose distribution evaluated in this study may further serve as a reference for evaluating the patient glandular dose at different depths based on the entrance exposure information. - Highlights: • CEDM techniques can enhance contrast uptake areas and suppress background tissue. • Dose for the dual-energy acquisition is about 20% higher than standard mode. • A new method is proposed to estimate the 3D dose distribution in dual-energy CEDM. • Depth of normalized dose ratio of 0.5 is less than but near 1 cm in the DE mode

Dose reconstruction modeling for medical radiation workers

International Nuclear Information System (INIS)

Choi, Yeong Chull; Cha, Eun Shil; Lee, Won Jin

2017-01-01

Exposure information is a crucial element for the assessment of health risk due to radiation. Radiation doses received by medical radiation workers have been collected and maintained by public registry since 1996. Since exposure levels in the remote past are greater concern, it is essential to reconstruct unmeasured doses in the past using known information. We developed retrodiction models for different groups of medical radiation workers and estimate individual past doses before 1996. Reconstruction models for past radiation doses received by medical radiation workers were developed, and the past doses were estimated. Using these estimates, organ doses should be calculated which, in turn, will be used to explore a wide range of health risks of medical occupational radiation exposure. Reconstruction models for past radiation doses received by medical radiation workers were developed, and the past doses were estimated. Using these estimates, organ doses should be calculated which, in turn, will be used to explore a wide range of health risks of medical occupational radiation exposure.

Dose reconstruction modeling for medical radiation workers

Energy Technology Data Exchange (ETDEWEB)

Choi, Yeong Chull; Cha, Eun Shil; Lee, Won Jin [Dept. of Preventive Medicine, Korea University, Seoul (Korea, Republic of)

2017-04-15

Exposure information is a crucial element for the assessment of health risk due to radiation. Radiation doses received by medical radiation workers have been collected and maintained by public registry since 1996. Since exposure levels in the remote past are greater concern, it is essential to reconstruct unmeasured doses in the past using known information. We developed retrodiction models for different groups of medical radiation workers and estimate individual past doses before 1996. Reconstruction models for past radiation doses received by medical radiation workers were developed, and the past doses were estimated. Using these estimates, organ doses should be calculated which, in turn, will be used to explore a wide range of health risks of medical occupational radiation exposure. Reconstruction models for past radiation doses received by medical radiation workers were developed, and the past doses were estimated. Using these estimates, organ doses should be calculated which, in turn, will be used to explore a wide range of health risks of medical occupational radiation exposure.

The dose and image quality in mammography in Macedonia

International Nuclear Information System (INIS)

Gershan, V.

2007-01-01

Complete test of publication follows. Mean Glandular Dose (MGD), dose distribution, phantom and quality of the real mammogram were studied for the first time in Macedonia. The study was conducted to review the condition of mammography equipment, to access the dose and image quality in mammography practices in Macedonia.. The purpose was to find out the weak points in the mammography practices in order to suggest improvements in the practices and establish quality control procedures. Under evaluation were 12 monographic machines. MGD was estimated using Entrance Surface Air KERMA at the breast surface K f measured free in air and appropriate conversion factors. Dose survey was curried by measurement and calculated of the HVLs and radiation output for 25-32 kVp and keeping record of the clinical parameters (breast thickness, kVp, mAs). Image quality was evaluated using the Mammographic Accreditation Phantom Gammex 156, PMMA plates and test tool for film processing.

Differential microRNA Analysis of Glandular Trichomes and Young Leaves in Xanthium strumarium L. Reveals Their Putative Roles in Regulating Terpenoid Biosynthesis.

Science.gov (United States)

Fan, Rongyan; Li, Yuanjun; Li, Changfu; Zhang, Yansheng

2015-01-01

The medicinal plant Xanthium strumarium L. (X. strumarium) is covered with glandular trichomes, which are the sites for synthesizing pharmacologically active terpenoids such as xanthatin. MicroRNAs (miRNAs) are a class of 21-24 nucleotide (nt) non-coding RNAs, most of which are identified as regulators of plant growth development. Identification of miRNAs involved in the biosynthesis of plant secondary metabolites remains limited. In this study, high-throughput Illumina sequencing, combined with target gene prediction, was performed to discover novel and conserved miRNAs with potential roles in regulating terpenoid biosynthesis in X. strumarium glandular trichomes. Two small RNA libraries from leaves and glandular trichomes of X. strumarium were established. In total, 1,185 conserved miRNAs and 37 novel miRNAs were identified, with 494 conserved miRNAs and 18 novel miRNAs being differentially expressed between the two tissue sources. Based on the X. strumarium transcriptome data that we recently constructed, 3,307 annotated mRNA transcripts were identified as putative targets of the differentially expressed miRNAs. KEGG (Kyoto Encyclopedia of Genes and Genomes) pathway analysis suggested that some of the differentially expressed miRNAs, including miR6435, miR5021 and miR1134, might be involved in terpenoid biosynthesis in the X. strumarium glandular trichomes. This study provides the first comprehensive analysis of miRNAs in X. strumarium, which forms the basis for further understanding of miRNA-based regulation on terpenoid biosynthesis.

Differential microRNA Analysis of Glandular Trichomes and Young Leaves in Xanthium strumarium L. Reveals Their Putative Roles in Regulating Terpenoid Biosynthesis.

Directory of Open Access Journals (Sweden)

Rongyan Fan

Full Text Available The medicinal plant Xanthium strumarium L. (X. strumarium is covered with glandular trichomes, which are the sites for synthesizing pharmacologically active terpenoids such as xanthatin. MicroRNAs (miRNAs are a class of 21-24 nucleotide (nt non-coding RNAs, most of which are identified as regulators of plant growth development. Identification of miRNAs involved in the biosynthesis of plant secondary metabolites remains limited. In this study, high-throughput Illumina sequencing, combined with target gene prediction, was performed to discover novel and conserved miRNAs with potential roles in regulating terpenoid biosynthesis in X. strumarium glandular trichomes. Two small RNA libraries from leaves and glandular trichomes of X. strumarium were established. In total, 1,185 conserved miRNAs and 37 novel miRNAs were identified, with 494 conserved miRNAs and 18 novel miRNAs being differentially expressed between the two tissue sources. Based on the X. strumarium transcriptome data that we recently constructed, 3,307 annotated mRNA transcripts were identified as putative targets of the differentially expressed miRNAs. KEGG (Kyoto Encyclopedia of Genes and Genomes pathway analysis suggested that some of the differentially expressed miRNAs, including miR6435, miR5021 and miR1134, might be involved in terpenoid biosynthesis in the X. strumarium glandular trichomes. This study provides the first comprehensive analysis of miRNAs in X. strumarium, which forms the basis for further understanding of miRNA-based regulation on terpenoid biosynthesis.

Modeling of radiation doses from chronic aqueous releases

International Nuclear Information System (INIS)

Watts, J.R.

1976-01-01

A general model and corresponding computer code were developed to calculate personnel dose estimates from chronic releases via aqueous pathways. Potential internal dose pathways are consumption of water, fish, crustacean, and mollusk. Dose prediction from consumption of fish, crustacean, or mollusk is based on the calculated radionuclide content of the water and applicable bioaccumulation factor. 70-year dose commitments are calculated for whole body, bone, lower large intestine of the gastrointestinal tract, and six internal organs. In addition, the code identifies the largest dose contributor and the dose percentages for each organ-radionuclide combination in the source term. The 1974 radionuclide release data from the Savannah River Plant were used to evaluate the dose models. The dose predicted from the model was compared to the dose calculated from radiometric analysis of water and fish samples. The whole body dose from water consumption was 0.45 mrem calculated from monitoring data and 0.61 mrem predicted from the model. Tritium contributed 99 percent of this dose. The whole body dose from fish consumption was 0.20 mrem calculated from monitoring data and 0.14 mrem from the model. Cesium-134,137 was the principal contributor to the 70-year whole body dose from fish consumption

Mesorad dose assessment model. Volume 1. Technical basis

International Nuclear Information System (INIS)

Scherpelz, R.I.; Bander, T.J.; Athey, G.F.; Ramsdell, J.V.

1986-03-01

MESORAD is a dose assessment model for emergency response applications. Using release data for as many as 50 radionuclides, the model calculates: (1) external doses resulting from exposure to radiation emitted by radionuclides contained in elevated or deposited material; (2) internal dose commitment resulting from inhalation; and (3) total whole-body doses. External doses from airborne material are calculated using semi-infinite and finite cloud approximations. At each stage in model execution, the appropriate approximation is selected after considering the cloud dimensions. Atmospheric processes are represented in MESORAD by a combination of Lagrangian puff and Gaussian plume dispersion models, a source depletion (deposition velocity) dry deposition model, and a wet deposition model using washout coefficients based on precipitation rates

Quality control, mean glandular dose estimate and room shielding calculation in mammography

International Nuclear Information System (INIS)

Rakotomalala, H.M.

2014-01-01

This study focuses in the importance of Radiation Protection in mammography. A good control of the radiological risk depends on the dose optimization, room shielding calculation and the quality of equipment. The work was carried out in the three private medical centers called A, B, and C. Dosimetry estimates were made on the equipment of the three centers. Values has been compared with the Diagnostic Reference Levels established by the International Atomic Energy Agency (IAEA). Conformity control of the radiological devices has also been done with the Mammographic Quality Control Kit of the INSTN-Madagascar. Verifications of shields of the room containing the mammography equipment were done by theoretical calculations using the method provided by NCRP 147. [fr

Radiation dose with digital breast tomosynthesis compared to digital mammography. Per-view analysis

Energy Technology Data Exchange (ETDEWEB)

Gennaro, Gisella [Veneto Institute of Oncology IOV- IRCCS, Radiology Unit, Padua (Italy); Bernardi, D. [Azienda Provinciale Servizi Sanitari (APSS), U.O. Senologia Clinica e Screening Mammografico, Department of Diagnostics, Trento (Italy); Houssami, N. [University of Sydney, Screening and Test Evaluation Program (STEP), School of Public Health, Sydney Medical School, Sydney (Australia)

2018-02-15

To compare radiation dose delivered by digital mammography (FFDM) and breast tomosynthesis (DBT) for a single view. 4,780 FFDM and 4,798 DBT images from 1,208 women enrolled in a screening trial were used to ground dose comparison. Raw images were processed by an automatic software to determine volumetric breast density (VBD) and were used together with exposure data to compute the mean glandular dose (MGD) according to Dance's model. DBT and FFDM were compared in terms of operation of the automatic exposure control (AEC) and MGD level. Statistically significant differences were found between FFDM and DBT MGDs for all views (CC: MGD{sub FFDM}=1.366 mGy, MGD{sub DBT}=1.858 mGy; p<0.0001; MLO: MGD{sub FFDM}=1.374 mGy, MGD{sub DBT}=1.877 mGy; p<0.0001). Considering the 4,768 paired views, Bland-Altman analysis showed that the average increase of DBT dose compared to FFDM is 38 %, and a range between 0 % and 75 %. Our findings show a modest increase of radiation dose to the breast by tomosynthesis compared to FFDM. Given the emerging role of DBT, its use in conjunction with synthetic 2D images should not be deterred by concerns regarding radiation burden, and should draw on evidence of potential clinical benefit. (orig.)

Severe glandular tularemia in a patient treated with anti-tumour necrosis factor for psoriatic arthritis

Directory of Open Access Journals (Sweden)

Ruxandra Calin

2017-07-01

Full Text Available A case of severe glandular tularemia in a patient receiving anti-tumour necrosis factor (TNF therapy is reported here. The patient required prolonged treatment with doxycycline–ciprofloxacin due to early relapse after ciprofloxacin was stopped. Tularemia may have a more severe course in patients receiving anti-TNF. This may thus be an indication for more aggressive treatment.

Single toxin dose-response models revisited

Energy Technology Data Exchange (ETDEWEB)

Demidenko, Eugene, E-mail: eugened@dartmouth.edu [Department of Biomedical Data Science, Geisel School of Medicine at Dartmouth, Hanover, NH03756 (United States); Glaholt, SP, E-mail: sglaholt@indiana.edu [Indiana University, School of Public & Environmental Affairs, Bloomington, IN47405 (United States); Department of Biological Sciences, Dartmouth College, Hanover, NH03755 (United States); Kyker-Snowman, E, E-mail: ek2002@wildcats.unh.edu [Department of Natural Resources and the Environment, University of New Hampshire, Durham, NH03824 (United States); Shaw, JR, E-mail: joeshaw@indiana.edu [Indiana University, School of Public & Environmental Affairs, Bloomington, IN47405 (United States); Chen, CY, E-mail: Celia.Y.Chen@dartmouth.edu [Department of Biological Sciences, Dartmouth College, Hanover, NH03755 (United States)

2017-01-01

The goal of this paper is to offer a rigorous analysis of the sigmoid shape single toxin dose-response relationship. The toxin efficacy function is introduced and four special points, including maximum toxin efficacy and inflection points, on the dose-response curve are defined. The special points define three phases of the toxin effect on mortality: (1) toxin concentrations smaller than the first inflection point or (2) larger then the second inflection point imply low mortality rate, and (3) concentrations between the first and the second inflection points imply high mortality rate. Probabilistic interpretation and mathematical analysis for each of the four models, Hill, logit, probit, and Weibull is provided. Two general model extensions are introduced: (1) the multi-target hit model that accounts for the existence of several vital receptors affected by the toxin, and (2) model with a nonzero mortality at zero concentration to account for natural mortality. Special attention is given to statistical estimation in the framework of the generalized linear model with the binomial dependent variable as the mortality count in each experiment, contrary to the widespread nonlinear regression treating the mortality rate as continuous variable. The models are illustrated using standard EPA Daphnia acute (48 h) toxicity tests with mortality as a function of NiCl or CuSO{sub 4} toxin. - Highlights: • The paper offers a rigorous study of a sigmoid dose-response relationship. • The concentration with highest mortality rate is rigorously defined. • A table with four special points for five morality curves is presented. • Two new sigmoid dose-response models have been introduced. • The generalized linear model is advocated for estimation of sigmoid dose-response relationship.

Maxilary glandular odontogenic cyst: case report = Cisto odontogênico glandular em maxila: relato de caso

Directory of Open Access Journals (Sweden)

Cardoso, Juliana Andrade

2015-01-01

Full Text Available Objetivo: O presente trabalho objetiva relatar um caso clínico de cisto odontogênico glandular (COG em maxila, cisto de desenvolvimento raro que pode apresentar comportamento agressivo e recidivante, dando ênfase no tratamento e proservação desta doença. Relato de Caso: Paciente faioderma, gênero feminino, 36 anos, foi encaminhada pelo Ortodontista por apresentar aumento de volume em maxila com abaulamento e crepitação. Foram realizadas radiografias e punção aspirativa. Uma vez observado o conteúdo da lesão, foi realizada a biópsia incisional e iniciada a descompressão com colocação de dreno rígido. Tendo a confirmação do diagnóstico para COG, a paciente foi submetida à cirurgia para remoção do cisto maxilar, através da enucleação cirúrgica, curetagem e osteotomia periférica. Conclusões: O COG é uma patologia incomum, recentemente reconhecida, cujo comportamento biológico pouco ainda se sabe. Sugere-se, portanto, a realização de investigações futuras sobre critérios para classificação de variáveis comumente utilizadas em estudos epidemiológicos, na tentativa de padronizar e possibilitar comparação entre estudos, todavia, para auxiliar em um diagnóstico bem sucedido

Effect of 935-MHz phone-simulating electromagnetic radiation on endometrial glandular cells during mouse embryo implantation.

Science.gov (United States)

Liu, Wenhui; Zheng, Xinmin; Qu, Zaiqing; Zhang, Ming; Zhou, Chun; Ma, Ling; Zhang, Yuanzhen

2012-10-01

This study examined the impact of 935MHz phone-simulating electromagnetic radiation on embryo implantation of pregnant mice. Each 7-week-old Kunming (KM) female white mouse was set up with a KM male mouse in a single cage for mating overnight after induction of ovulation. In the first three days of pregnancy, the pregnant mice was exposed to electromagnetic radiation at low-intensity (150 μW/cm(2), ranging from 130 to 200 μW/cm(2), for 2- or 4-h exposure every day), mid-intensity (570 μW/cm(2), ranging from 400 to 700 μW/cm(2), for 2- or 4-h exposure every day) or high-intensity (1400 μW/cm(2), ranging from 1200 to 1500 μW/cm(2), for 2- or 4-h exposure every day), respectively. On the day 4 after gestation (known as the window of murine embryo implantation), the endometrium was collected and the suspension of endometrial glandular cells was made. Laser scanning microscopy was employed to detect the mitochondrial membrane potential and intracellular calcium ion concentration. In high-intensity, 2- and 4-h groups, mitochondrial membrane potential of endometrial glandular cells was significantly lower than that in the normal control group (Pelectromagnetic radiation and longer length of the radiation are required to inflict a remarkable functional and structural damage to mitochondrial membrane. Our data demonstrated that electromagnetic radiation with a 935-MHz phone for 4 h conspicuously decreased mitochondrial membrane potential and lowered the calcium ion concentration of endometrial glandular cells. It is suggested that high-intensity electromagnetic radiation is very likely to induce the death of embryonic cells and decrease the chance of their implantation, thereby posing a high risk to pregnancy.

Metastatic Urothelial Carcinoma with Glandular Differentiation That Confirmed the Response by Autopsy Specimen to Second-Line mFOLFOX6 (Fluorouracil, Oxaliplatin, and Leucovorin plus Bevacizumab Chemotherapy

Directory of Open Access Journals (Sweden)

Taku Naiki

2017-11-01

Full Text Available The prognostic significance of glandular differentiation in urothelial carcinoma (UC is controversial, and thus far there is no established treatment strategy against metastasis of glandular component. We describe here a case of metastatic UC with glandular differentiation that had histological disappearance of adenocarcinoma components at autopsy after sequential chemotherapy with S-1 and cisplatin (CDDP and with mFOLFOX6 (fluorouracil, oxaliplatin, and leucovorin plus bevacizumab (mFOLFOX6+Bev. A 62-year-old Asian male was diagnosed with invasive UC with glandular differentiation (T2N0M0 by radical cystectomy and ileal conduit, and careful follow-up observation was made. Eight years after radical operation, peritoneal metastases occurred, and a biopsy specimen using colon fiber revealed high-grade adenocarcinomas with an immunohistochemical profile that included positivity for cytokeratin 7 (CK7 and negativity for cytokeratin 20 (CK20 and uroplakin, which was identical to the radical cystectomy specimen. Thus, he received combination chemotherapy consisting of S-1 and CDDP; however, the peritoneal metastasis worsened after 2 cycles. Therefore, second-line mFOLFOX6+Bev chemotherapy was performed for a total of 5 courses. In spite of this, the patient died, and the final diagnosis by autopsy was multiple metastases of infiltrating pure UC to the lung, bone, and peritoneum. Interestingly, there were no pathological findings of adenocarcinoma, and the immunohistochemical profile of the metastatic lesions was identical to that of the previous specimens from the bladder and colon. This suggests that sequential chemotherapy of S-1 and CDDP and second-line mFOLFOX6+Bev might be a feasible option in metastatic UC with glandular differentiation.

Modelling of the mammographic exposure conditions for radiological detriment study in the Valencian Breast Cancer Screening Programme

International Nuclear Information System (INIS)

Ferrer, S.; Ramos, M.; Villaescusa, J. I.; Verdu, G.; Salas, M. D.; Cuevas, M. D.

2005-01-01

Breast screening programmes are the best weapon to fight against breast cancer. Nevertheless, despite the benefits, this practice supposes a radiological risk that cannot be forgotten. In order to calculate breast glandular doses, different MCNP-4C2 models have been developed, simulating the exposure conditions. Radiological detriments have been transported from the population under study in the UNSCEAR 2000 to the Valencian Community, obtaining the detection-induced cancer ratio (DICR) for this population. (authors)

Urban contamination and dose model

International Nuclear Information System (INIS)

Robertson, E.; Barry, P.J.

1995-10-01

Nuclear power reactors and other nuclear facilities are being built near or even within urban centres. Accidental releases of radionuclides to the atmosphere in built-up areas result in radiological exposure pathways that differ from those caused by releases in rural environments. Other than inhalation, exposure pathways involve external radiation from the plume while it passes and from radioactivity deposited onto the many and varied surfaces after it has passed. Radiation fields inside buildings are attenuated but many people are potentially exposed so while individual doses may be relatively low, population integrated doses may be high enough to cause concern. It is important, therefore, to assess the potential exposures and to estimate the cost-effectiveness of dose reduction measures in urban environments. This report describes a model developed to carry out such assessments. The model draws heavily on experience gained in European cities after their contamination fallout from the Chernobyl accident. Input is time integrated concentrations of specific radionuclides in urban air, obtained either by direct measurement or by prediction using an atmospheric dispersion model. The code includes default values for site specific variables and transfer parameters but the user is invited if desired to enter other values from the keyboard. Output is the time integrated dose rates for individuals selected because of the characteristic living, working and recreational habits. An accompanying manual documents the technical background on which the model is based and leads a first-time suer through various steps and operations encountered while the model is running. (author). 60 refs., 10 tabs., 1 fig

Functional effects of proinflammatory factors present in Sjögren's syndrome salivary microenvironment in an in vitro model of human salivary gland.

Science.gov (United States)

Arce-Franco, Mayte; Dominguez-Luis, María; Pec, Martina K; Martínez-Gimeno, Carlos; Miranda, Pablo; Alvarez de la Rosa, Diego; Giraldez, Teresa; García-Verdugo, José María; Machado, José David; Díaz-González, Federico

2017-09-19

Primary Sjögren's syndrome (pSS) is an autoimmune exocrinopathy in which the role that the immune response plays in reducing exocrine gland function, including the glandular microenvironment of cytokines, has not been fully understood. Epithelial cells from biopsies of human parotid gland (HPG) were used to establish a model of human salivary gland in vitro. In this model, the functional consequences of several proinflammatory soluble factors present in the pSS glandular microenvironment were assessed. Stimulation with isoproterenol and calcium produced a significant increase in the basal activity of amylase in the HPG cell supernatants. Under these conditions, the presence of TNF-α and CXCL12 increased amylase mRNA cellular abundance, but reduced the amylase activity in the cell-free supernatant in a dose-dependent manner. IL-1β and IFN-γ, but not TGF-β, also diminished amylase secretion by HPG cells. These results suggest that the glandular microenvironment of cytokine, by acting post-transcriptionally, may be responsible, at least in part, for the reduced exocrine function observed in pSS patients. These data may help to a better understanding of the pathogenesis of SS, which in turn would facilitate the identification of new therapeutic targets for this disorder.

Human papillomavirus prevalence and type-distribution in cervical glandular neoplasias

DEFF Research Database (Denmark)

Holl, Katsiaryna; Nowakowski, Andrzej M; Powell, Ned

2015-01-01

Cervical glandular neoplasias (CGN) present a challenge for cervical cancer prevention due to their complex histopathology and difficulties in detecting preinvasive stages with current screening practices. Reports of human papillomavirus (HPV) prevalence and type-distribution in CGN vary, providing...... uncertain evidence to support prophylactic vaccination and HPV screening. This study [108288/108290] assessed HPV prevalence and type-distribution in women diagnosed with cervical adenocarcinoma in situ (AIS, N = 49), adenosquamous carcinoma (ASC, N = 104), and various adenocarcinoma subtypes (ADC, N = 461...... of CGN are HPV16/18/45-positive, the incorporation of prophylactic vaccination and HPV testing in cervical cancer screening are important prevention strategies. Our results suggest that special attention should be given to certain rarer ADC subtypes as most appear to be unrelated to HPV....

Nonlinear model of high-dose implantation

International Nuclear Information System (INIS)

Danilyuk, A.

2001-01-01

The models of high-dose implantation, using the distribution functions, are relatively simple. However, they must take into account the variation of the function of distribution of the implanted ions with increasing dose [1-4]. This variation takes place owing to the fact that the increase of the concentration of the implanted ions results in a change of the properties of the target. High-dose implantation is accompanied by sputtering, volume growth, diffusion, generation of defects, formation of new phases, etc. The variation of the distribution function is determined by many factors and is not known in advance. The variation within the framework of these models [1-4] is taken into account in advance by the introduction of intuitive assumptions on the basis of implicit considerations. Therefore, these attempts should be regarded as incorrect. The model prepared here makes it possible to take into account the sputtering of the target, volume growth and additional declaration on the implanted ions. Without any assumptions in relation to the variation of the distribution function with increasing dose. In our model it is assumed that the type of distribution function for small doses in a pure target substance is the same as in substances with implanted ions. A second assumption relates to the type of the distribution function valid for small doses in the given substances. These functions are determined as a result of a large number of theoretical and experimental investigations and are well-known at the present time. They include the symmetric and nonsymmetric Gauss distribution, the Pearson distribution, and others. We examine implantation with small doses of up to 10 14 - 10 15 cm -2 when the accurately known distribution is valid

Effect of Low-Dose Aspirin on Chronic Acid Reflux Esophagitis in Rats.

Science.gov (United States)

Masuda, Takahiro; Yano, Fumiaki; Omura, Nobuo; Tsuboi, Kazuto; Hoshino, Masato; Yamamoto, Se Ryung; Akimoto, Shunsuke; Kashiwagi, Hideyuki; Yanaga, Katsuhiko

2018-01-01

Clinical role of low-dose aspirin (LDA) in pathogenesis of gastroesophageal reflux disease is by far controversial. This can be attributed to the paucity of basic research detailing the mechanism of LDA-induced esophageal mucosal injury (EI) on underlying chronic acid reflux esophagitis (RE). The aim of this study was to clarify the effect of LDA on chronic RE in rats. Esophagitis was induced in 8-week-old male Wistar rats by ligating the border between forestomach and glandular portion with a 2-0 silk tie and covering the duodenum with a small piece of 18-Fr Nélaton catheter. Seventy-eight chronic RE rat models were divided into five treatment groups, consisting of orally administered vehicle (controls), and aspirin doses of 2, 5, 50 or 100 mg/kg once daily for 28 days. EI was assessed by gross area of macroscopic mucosal injury, severity grade of esophagitis and microscopic depth of infiltration by inflammatory cells. Area of esophagitis in animals with aspirin dose of 100 mg/kg/day showed a 36.5% increase compared with controls, although it failed to achieve statistical significance (p = 0.812). Additionally, the rate of severe EI was increased in animals with aspirin dose of 100 mg/kg/day as compared with controls (p aspirin (100 mg/kg/day) contributed in exacerbating preexisting EI. LDA (2 and 5 mg/kg/day), on the other hand, did not affect chronic RE in this model. LDA seems to be safe for use in patients with chronic RE.

[Markers of stromal invasion during background and precancerous changes of the glandular epithelium and in adenocarcinoma of the cervix uteri].

Science.gov (United States)

Danilova, N V; Andreeva, Iu Iu; Zavalishina, L É; Mal'kov, P G

2012-01-01

It is very difficult to identify stromal invasion when the glandular epithelium of the cervix uteri is involved. It is necessary to draw a clear distinction between its glandular structures and adenocarcinoma in situ, involving the preexisting crypts and invasive glands. An attempt was made to assess the possibilities of using as markers of invasion the following stromal proteins and adhesion molecules: CD44, E-cadherin, beta-catenin, tenascin, and laminin. Fifty-three cases of benign glandular changes, 66 cases of dysplasias and adenocarcinomas in situ, and 47 cases of invasive adenocarcinoma were examined. An immunohistochemical study was performed according to the standard protocol using the antibodies to CD44, laminin, tenascin, E-cadherin, and beta-catenin and a semiquantitative assessment of results was made. CD44 was found to be redistributed from the cells to the tumor stroma. CD44 was not detected in the stroma surrounding the intact glands, so were benign epithelial changes. In the tumor environment, there was, on the contrary, a reaction with CD44 in 74.5% of invasive adenocarcinomas cases (p 0.05). CD44 and tenascin are of great diagnostic value in examining invasive and microinvasive adenocarcinomas of the cervix uteri. E-cadherin and beta-catenin are of no diagnostic value in the study groups of pathological processes. Laminin is a potential marker of stromal invasion; however, its expression calls for further investigation.

Some hybrid models applicable to dose-response relationships

International Nuclear Information System (INIS)

Kumazawa, Shigeru

1992-01-01

A new type of models of dose-response relationships has been studied as an initial stage to explore a reliable extrapolation of the relationships decided by high dose data to the range of low dose covered by radiation protection. The approach is to use a 'hybrid scale' of linear and logarithmic scales; the first model is that the normalized surviving fraction (ρ S > 0) in a hybrid scale decreases linearly with dose in a linear scale, and the second is that the induction in a log scale increases linearly with the normalized dose (τ D > 0) in a hybrid scale. The hybrid scale may reflect an overall effectiveness of a complex system against adverse events caused by various agents. Some data of leukemia in the atomic bomb survivors and of rodent experiments were used to show the applicability of hybrid scale models. The results proved that proposed models fit these data not less than the popular linear-quadratic models, providing the possible interpretation of shapes of dose-response curves, e.g. shouldered survival curves varied by recovery time. (author)

MORPHOLOGIC CONSIDERATIONS ABOUT THE WALL OF THE GLANDULAR STOMACH OF YOUNG RABBITS (Oryctolagus cuniculus)

OpenAIRE

de Oliveira, Larissa Renata; Molinari, Sonia Lucy; Natali, Maria Raquel Marçal; Michelan, Andrea Cristiane; Scapinello, Claúdio

2001-01-01

The morphology of the stomach may vary between species as a function of feeding habits, differences on the cellular composition of the mucosa of the stomach wall and the different functions it carries out. Morphofunctional variations of the stomach of several animals along phylogeny led us to investigate the morphology of the wall of the glandular stomach of rabbits. We used the stomachs of 32 young rabbits (Oryctolagus cuniculus) from the White New Zealand strain, coming from the Experimenta...

Application of a Novel Dose-Uncertainty Model for Dose-Uncertainty Analysis in Prostate Intensity-Modulated Radiotherapy

International Nuclear Information System (INIS)

Jin Hosang; Palta, Jatinder R.; Kim, You-Hyun; Kim, Siyong

2010-01-01

Purpose: To analyze dose uncertainty using a previously published dose-uncertainty model, and to assess potential dosimetric risks existing in prostate intensity-modulated radiotherapy (IMRT). Methods and Materials: The dose-uncertainty model provides a three-dimensional (3D) dose-uncertainty distribution in a given confidence level. For 8 retrospectively selected patients, dose-uncertainty maps were constructed using the dose-uncertainty model at the 95% CL. In addition to uncertainties inherent to the radiation treatment planning system, four scenarios of spatial errors were considered: machine only (S1), S1 + intrafraction, S1 + interfraction, and S1 + both intrafraction and interfraction errors. To evaluate the potential risks of the IMRT plans, three dose-uncertainty-based plan evaluation tools were introduced: confidence-weighted dose-volume histogram, confidence-weighted dose distribution, and dose-uncertainty-volume histogram. Results: Dose uncertainty caused by interfraction setup error was more significant than that of intrafraction motion error. The maximum dose uncertainty (95% confidence) of the clinical target volume (CTV) was smaller than 5% of the prescribed dose in all but two cases (13.9% and 10.2%). The dose uncertainty for 95% of the CTV volume ranged from 1.3% to 2.9% of the prescribed dose. Conclusions: The dose uncertainty in prostate IMRT could be evaluated using the dose-uncertainty model. Prostate IMRT plans satisfying the same plan objectives could generate a significantly different dose uncertainty because a complex interplay of many uncertainty sources. The uncertainty-based plan evaluation contributes to generating reliable and error-resistant treatment plans.

A Generalized QMRA Beta-Poisson Dose-Response Model.

Science.gov (United States)

Xie, Gang; Roiko, Anne; Stratton, Helen; Lemckert, Charles; Dunn, Peter K; Mengersen, Kerrie

2016-10-01

Quantitative microbial risk assessment (QMRA) is widely accepted for characterizing the microbial risks associated with food, water, and wastewater. Single-hit dose-response models are the most commonly used dose-response models in QMRA. Denoting PI(d) as the probability of infection at a given mean dose d, a three-parameter generalized QMRA beta-Poisson dose-response model, PI(d|α,β,r*), is proposed in which the minimum number of organisms required for causing infection, K min , is not fixed, but a random variable following a geometric distribution with parameter 0Poisson model, PI(d|α,β), is a special case of the generalized model with K min = 1 (which implies r*=1). The generalized beta-Poisson model is based on a conceptual model with greater detail in the dose-response mechanism. Since a maximum likelihood solution is not easily available, a likelihood-free approximate Bayesian computation (ABC) algorithm is employed for parameter estimation. By fitting the generalized model to four experimental data sets from the literature, this study reveals that the posterior median r* estimates produced fall short of meeting the required condition of r* = 1 for single-hit assumption. However, three out of four data sets fitted by the generalized models could not achieve an improvement in goodness of fit. These combined results imply that, at least in some cases, a single-hit assumption for characterizing the dose-response process may not be appropriate, but that the more complex models may be difficult to support especially if the sample size is small. The three-parameter generalized model provides a possibility to investigate the mechanism of a dose-response process in greater detail than is possible under a single-hit model. © 2016 Society for Risk Analysis.

Severe glandular tularemia in a patient treated with anti-tumour necrosis factor for psoriatic arthritis.

Science.gov (United States)

Calin, Ruxandra; Caumes, Eric; Reibel, Florence; Ali Mohamed, Anzime; Brossier, Florence; Foltz, Violaine; Boussouar, Samia; Fautrel, Bruno; Maurin, Max; Katlama, Christine; Pourcher, Valérie

2017-07-01

A case of severe glandular tularemia in a patient receiving anti-tumour necrosis factor (TNF) therapy is reported here. The patient required prolonged treatment with doxycycline-ciprofloxacin due to early relapse after ciprofloxacin was stopped. Tularemia may have a more severe course in patients receiving anti-TNF. This may thus be an indication for more aggressive treatment. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

Bone and marrow dose modeling

International Nuclear Information System (INIS)

Stabin, Michael G.

2004-01-01

Nuclear medicine therapy is being used increasingly in the treatment of cancer (thyroid, leukemia/lymphoma with RIT, primary and secondary bone malignancies, and neuroblastomas). In all cases it is marrow toxicity that limits the amount of treatment that can be administered safely. Marrow dose calculations are more difficult than for many major organs because of the intricate association of bone and soft tissue elements. In RIT, there appears to be no consensus on how to calculate that dose accurately, or of individual patients ability to tolerate planned therapy. Available dose models are designed after an idealized average, healthy individual. Patient-specific methods are applied in evaluation of biokinetic data, and need to be developed for treatment of the physical data (dose conversion factors) as well: age, prior patient therapy, disease status. Contributors to marrow dose: electrons and photons

Dose assessment models. Annex A

International Nuclear Information System (INIS)

1982-01-01

The models presented in this chapter have been separated into 2 general categories: environmental transport models which describe the movement of radioactive materials through all sectors of the environment after their release, and dosimetric models to calculate the absorbed dose following an intake of radioactive materials or exposure to external irradiation. Various sections of this chapter also deal with atmospheric transport models, terrestrial models, and aquatic models.

Correlação dos aspectos laparoscópicos com as alterações histológicas glandulares das lesões endometrióticas peritoneais Correlation between laparoscopic aspects and glandular hystological findings of peritoneal endometriotic lesions

Directory of Open Access Journals (Sweden)

Francesco Antonio Viscomi

2004-09-01

Full Text Available OBJETIVOS: Correlacionar os aspectos laparoscópicos com os achados histológicos na endometriose peritoneal para facilitar a compreensão da teoria evolutiva da endometriose. MÉTODOS: Foram selecionadas aleatoriamente para o presente estudo prospectivo 67 pacientes submetidas a laparoscopia, com diagnóstico de endometriose peritoneal. A avaliação laparoscópica foi baseada no aspecto visual do implante suspeito de endometriose peritoneal, submetido a estudo anatomopatológico. De acordo com o aspecto laparoscópico, as lesões foram agrupadas em: grupo V - vermelhas, grupo N - negras, grupo B - brancas. A avaliação histológica foi realizada observando-se as características funcionais do epitélio glandular, a presença de debris intraluminais, o número de mitoses e a relação estroma/glândula. RESULTADOS: As características funcionais do epitélio glandular mostraram associação estatisticamente significante entre os grupos, sendo o epitélio com carcterística secretora encontrado em 68,4% das lesões do grupo V, 15,8% do grupo N e B, enquanto que o epitélio incaracterístico foi encontrado em 19,4% das lesões vermelhas, 38,7% das lesões negras e 41,9% das brancas e o epitélio proliferativo foi observado em 50% das pacientes do grupo B e em 25% dos grupos V e N (p=0,011. Em relação à presença de debris intraluminais, também houve diferença significante entre os grupos, estando presentes em 58,4% das lesões negras, 33,3% das lesões brancas e 8,3% das lesões vermelhas (p=0,016. Quanto ao número de mitoses, não houve diferença significante nos três grupos de estudo (p=0,428. O mesmo foi observado na relação estroma/glândula, não havendo diferença significante nos grupos de estudo (p=0,159. CONCLUSÃO: A associação entre atividade funcional nas lesões vermelhas e baixa atividade funcional nas lesões negras e brancas, bem como a presença de debris intraluminais nos diferentes grupos, reforçam a teoria

Image quality and dose in mammographic images obtained in Mexico City hospitals

International Nuclear Information System (INIS)

Ruiz-Trejo, C.; Brandan, M.-E.; Verdejo, M.; Flores, A.; Guevara, M.; Martin, J.; Madero-Preciado, L.

2001-01-01

The performance of three mammographic systems in large Mexican hospitals has been evaluated, as well as the image quality and associated dose. Quality control tests include examination of X-ray equipment, darkroom conditions, film processor, and viewboxes. Systems referred to as '1', '2', and '3' passed 50%, 75% and 75% of these tests, respectively. Quality image is assessed using five images obtained under similar nominal conditions in each X-ray equipment. System 1 generates no image of acceptable quality, while equipment 2 and 3 produce one and two, respectively. The mean glandular dose for the best images obtained in each service with an accreditation phantom has been measured, and the values are 1.4 mGy, 1.6 mGy, and 1.0 mGy, respectively. (author)

Comparison between linear quadratic and early time dose models

International Nuclear Information System (INIS)

Chougule, A.A.; Supe, S.J.

1993-01-01

During the 70s, much interest was focused on fractionation in radiotherapy with the aim of improving tumor control rate without producing unacceptable normal tissue damage. To compare the radiobiological effectiveness of various fractionation schedules, empirical formulae such as Nominal Standard Dose, Time Dose Factor, Cumulative Radiation Effect and Tumour Significant Dose, were introduced and were used despite many shortcomings. It has been claimed that a recent linear quadratic model is able to predict the radiobiological responses of tumours as well as normal tissues more accurately. We compared Time Dose Factor and Tumour Significant Dose models with the linear quadratic model for tumour regression in patients with carcinomas of the cervix. It was observed that the prediction of tumour regression estimated by the Tumour Significant Dose and Time Dose factor concepts varied by 1.6% from that of the linear quadratic model prediction. In view of the lack of knowledge of the precise values of the parameters of the linear quadratic model, it should be applied with caution. One can continue to use the Time Dose Factor concept which has been in use for more than a decade as its results are within ±2% as compared to that predicted by the linear quadratic model. (author). 11 refs., 3 figs., 4 tabs

Antibodies against Escherichia coli O24 and O56 O-Specific Polysaccharides Recognize Epitopes in Human Glandular Epithelium and Nervous Tissue

Science.gov (United States)

Korzeniowska-Kowal, Agnieszka; Kochman, Agata; Gamian, Elżbieta; Lis-Nawara, Anna; Lipiński, Tomasz; Seweryn, Ewa; Ziółkowski, Piotr; Gamian, Andrzej

2015-01-01

Lipopolysaccharide (LPS), the major component of the outer membrane of Gram-negative bacteria, contains the O-polysaccharide, which is important to classify bacteria into different O-serological types within species. The O-polysaccharides of serotypes O24 and O56 of E. coli contain sialic acid in their structures, already established in our previous studies. Here, we report the isolation of specific antibodies with affinity chromatography using immobilized lipopolysaccharides. Next, we evaluated the reactivity of anti-O24 and anti-O56 antibody on human tissues histologically. The study was conducted under the assumption that the sialic acid based molecular identity of bacterial and tissue structures provides not only an understanding of the mimicry-based bacterial pathogenicity. Cross-reacting antibodies could be used to recognize specific human tissues depending on their histogenesis and differentiation, which might be useful for diagnostic purposes. The results indicate that various human tissues are recognized by anti-O24 and anti-O56 antibodies. Interestingly, only a single specific reactivity could be found in the anti-O56 antibody preparation. Several tissues studied were not reactive with either antibody, thus proving that the presence of cross-reactive antigens was tissue specific. In general, O56 antibody performed better than O24 in staining epithelial and nervous tissues. Positive staining was observed for both normal (ganglia) and tumor tissue (ganglioneuroma). Epithelial tissue showed positive staining, but an epitope recognized by O56 antibody should be considered as a marker of glandular epithelium. The reason is that malignant glandular tumor and its metastasis are stained, and also epithelium of renal tubules and glandular structures of the thyroid gland are stained. Stratified epithelium such as that of skin is definitely not stained. Therefore, the most relevant observation is that the epitope recognized by anti-O56 antibodies is a new marker

Comparative study of dose estimation in the change a conventional mammography to digital mammography

International Nuclear Information System (INIS)

Vazquez Vazquez, R.; Otero Martinez, C.; Soto Bua, M.; Santamarina Vazquez, F.; Carril Iglesias, S.; Lobato Busto, R.; Luna Vega, V.; Mosquera Sueiro, J.; Sqanchez Garcia, M.; Pombar Camean, M.

2011-01-01

Mammographic studies are now one of the most demanding radiological because of its effectiveness in detecting breast cancer early. The introduction of digital mammography has been a major advance because it has overcome some of the limitations of conventional systems. Due to the nature of the radiosensitive glandular tissue becomes very important control of the dose given to patients. In the present study is to analyze the variations in dosimetry that can exist between a conventional mammography and digital mammography.

Evaluation of bismuth shielding effectiveness in reducing breast absorbed dose during thoracic CT scan

Energy Technology Data Exchange (ETDEWEB)

Alonso, T. C.; Mourao, A. P.; Santana, P. C.; Silva, T. A. [Federal University of Minas Gerais, Program of Nuclear Science and Techniques, Av. Pte. Antonio Carlos 6627, 31270-901 Belo Horizonte, Minas Gerais (Brazil)

2015-10-15

Computed Tomography (CT) is an essential method for tracking neoplasia and efficiently diagnosing a wide variety of thoracic diseases. CT is generally considered the most accurate choice for lung examination. Due to the growing use of CT, breast and other superficial and radiosensitive organs are unnecessarily irradiated during radiological procedures, thus requiring the development of strategies appropriate to optimize and, if possible, to reduce the radiation dose. The use of bismuth shielding to reduce radiation dose absorbed by breast during thoracic CT examinations has been the subject of many studies recently published by Brazilian and foreign authors of various fields. The purpose of this paper is both to accurately determine the glandular dose when breast is exposed to radiation and to assess the reduction in absorbed dose during thoracic CT examinations, using a set of Thermoluminescent Dosimeters, an anthropomorphic phantom and bismuth shielding. (Author)

Evaluation of bismuth shielding effectiveness in reducing breast absorbed dose during thoracic CT scan

International Nuclear Information System (INIS)

Alonso, T. C.; Mourao, A. P.; Santana, P. C.; Silva, T. A.

2015-10-01

Computed Tomography (CT) is an essential method for tracking neoplasia and efficiently diagnosing a wide variety of thoracic diseases. CT is generally considered the most accurate choice for lung examination. Due to the growing use of CT, breast and other superficial and radiosensitive organs are unnecessarily irradiated during radiological procedures, thus requiring the development of strategies appropriate to optimize and, if possible, to reduce the radiation dose. The use of bismuth shielding to reduce radiation dose absorbed by breast during thoracic CT examinations has been the subject of many studies recently published by Brazilian and foreign authors of various fields. The purpose of this paper is both to accurately determine the glandular dose when breast is exposed to radiation and to assess the reduction in absorbed dose during thoracic CT examinations, using a set of Thermoluminescent Dosimeters, an anthropomorphic phantom and bismuth shielding. (Author)

Investigation on 3D dose distribution in digital breast tomosynthesis

Science.gov (United States)

Masi, M.

2017-03-01

Monte Carlo calculations for dosimetry in digital breast tomosynthesis (DBT) require experimental validations. We measured the 3D dose distribution in a breast phantom in a DBT scan, using XR-QA2 radiochromic films. We positioned film pieces at the entrance surface, at the bottom surface and at four depths between adjacent slabs in the 5-slabs, 5-cm-thick phantom simulating a compressed breast with 50% glandular fraction. We irradiated the phantom at 40kV (half value layer 1.1mm Al) for three angular tilting of the beam central axis ( {±}25° and 0° normal incidence). We determined the transverse and longitudinal distributions of the average dose in the phantom (in terms of air kerma normalized to the entrance air kerma), showing the angular dependence of the depth-resolved 3D dose distributions. In transverse planes the maximum dose variations were between 5.0% and 14.8% for normal incidence, and by 8.6% from the central to the tilted view. In the direction of the beam axis, the dose decreases up to about 71% from the entrance to the exit value. The extimated backscatter fraction was between 3% and 8%.

Embracing model-based designs for dose-finding trials.

Science.gov (United States)

Love, Sharon B; Brown, Sarah; Weir, Christopher J; Harbron, Chris; Yap, Christina; Gaschler-Markefski, Birgit; Matcham, James; Caffrey, Louise; McKevitt, Christopher; Clive, Sally; Craddock, Charlie; Spicer, James; Cornelius, Victoria

2017-07-25

Dose-finding trials are essential to drug development as they establish recommended doses for later-phase testing. We aim to motivate wider use of model-based designs for dose finding, such as the continual reassessment method (CRM). We carried out a literature review of dose-finding designs and conducted a survey to identify perceived barriers to their implementation. We describe the benefits of model-based designs (flexibility, superior operating characteristics, extended scope), their current uptake, and existing resources. The most prominent barriers to implementation of a model-based design were lack of suitable training, chief investigators' preference for algorithm-based designs (e.g., 3+3), and limited resources for study design before funding. We use a real-world example to illustrate how these barriers can be overcome. There is overwhelming evidence for the benefits of CRM. Many leading pharmaceutical companies routinely implement model-based designs. Our analysis identified barriers for academic statisticians and clinical academics in mirroring the progress industry has made in trial design. Unified support from funders, regulators, and journal editors could result in more accurate doses for later-phase testing, and increase the efficiency and success of clinical drug development. We give recommendations for increasing the uptake of model-based designs for dose-finding trials in academia.

Forest food chain and dose model (FDMF) for RODOS. Model description

International Nuclear Information System (INIS)

Rantavaara, A.; Vetikko, V.; Calmon, P.; Wendt, J.

2001-12-01

In the early phase of a large-scale fallout situation, both access to forests and the use of wild foods may need temporal restrictions. In a later phase wild foods and internal doses received through them may still need surveillance of radioactivity. After accidental fallout a major source of external radiation are the ground deposits, and in forests contaminated overstorey can also be a considerable source. For consideration of dose pathways related to forests during a nuclear emergency the Forest Food Chain and Dose Model (FDMF) was developed. It is an integral part of RODOS, a real-time, on-line decision support system for off-site emergency management in Europe. The forest module FDMF receives radionuclide concentrations in air as input from the air dispersion model of RODOS, and calculates activities deposited on various parts of the forest. The model simulates the transfer of radionuclides in the forest ecosystem. It quantifies the dynamic changes for three types of forests, typical of a region. The model gives the contamination of forest products and dose rate for external radiation as a function of time. External and internal radiation doses for various population groups according to their stay in forests and their use of forest products can be assessed since the first year until the 50 th year after the fallout event. Doses are calculated for children and adults representing the public, and ingestion doses also for pickers of berries and mushrooms, and hunters. Forest workers are a special group due to their potentially enhanced external dose from outdoor working. The model results can be shown as spatial distributions on top of geographical maps. Many parameters in the FDMF database are regional and have to be adjusted when the model is adapted for local conditions or new radioecological regions. Long-term predictions will be considerably improved when site-specific parameters are used. STUK developed the forest module together with IPSN (Institut de

Modelling simple helically delivered dose distributions

International Nuclear Information System (INIS)

Fenwick, John D; Tome, Wolfgang A; Kissick, Michael W; Mackie, T Rock

2005-01-01

In a previous paper, we described quality assurance procedures for Hi-Art helical tomotherapy machines. Here, we develop further some ideas discussed briefly in that paper. Simple helically generated dose distributions are modelled, and relationships between these dose distributions and underlying characteristics of Hi-Art treatment systems are elucidated. In particular, we describe the dependence of dose levels along the central axis of a cylinder aligned coaxially with a Hi-Art machine on fan beam width, couch velocity and helical delivery lengths. The impact on these dose levels of angular variations in gantry speed or output per linear accelerator pulse is also explored

Detection of cervical intraepithelial neoplasia in women with atypical squamous or glandular cells of undetermined significance cytology: a prospective study

NARCIS (Netherlands)

Wensveen, Celesta; Kagie, Marjolein; Veldhuizen, Roel; de Groot, Christianne; Denny, Lynette; Zwinderman, Koos; Trimbos, Baptist

2003-01-01

(1) To assess the prevalence of histologically confirmed cervical intraepithelial neoplasia in patients with cervical smears diagnosed as atypical squamous or glandular cells of undetermined significance. (2) To evaluate the role of colposcopy and the presence of human papillomavirus in detecting

False positive reaction due to endogenous biotin activity in glandular epithelium of decidua Reação falso positiva em epitélio glandular da decídua devido a atividade endógena de biotina

Directory of Open Access Journals (Sweden)

Liliana Cruz Spano

2005-06-01

Full Text Available Biotin-labeled probe was used in an in situ hybridisation assay to localize virus infection in formalin-fixed, paraffin embedded tissues taken from eleven abortion cases. Probes for human cytomegalovirus (HCMV, human Parvovirus B19 (B19 and human adenovirus type 2 (HAd2, were labeled with biotin-11-dUTP by nick-translation reaction. Streptavidin-alkaline-phosphatase (SAP was used to detect biotin, followed by 4-nitroblue tetrazolium/5-bromo-4-chloro-3-indolyl phosphate (NBT/BCIP solution. Positive reaction was observed in nucleus of glandular ephitelium cells of decidua either in positive or in negative control at first and second gestational trimester. The reaction was not inhibited with blocking solution for alkaline phosphatase endogenous activity and it persisted even with probes omission. The use of adequate negative control permitted to reveal the presence of nuclear biotin in glandular epithelium of decidua, responsible for false positivity in detection systems involving streptavidin biotin system (StrepABC. The stained cells resembled to cytophatic effect due to herpesvirus, which could induce further misinterpretation. The results obtained in this study strongly recommend that DNA detection by in situ hybridisation reaction in gestational endometrium should be done without using StrepABC system.Sondas marcadas com biotina foram utilizadas neste trabalho para detecção de infecção viral por hibridização in situ em tecidos fixados com formalina e embebidos em parafina de 11 casos obtidos de abortamento. Sondas para citomegalovírus humano (HCMV, parvovírus B19 humano (B19 e adenovírus humano tipo 2 (HAd2, foram marcadas com biotina-11-dUTP através da reação de nick-translation. Estreptavidina conjugada com fosfatase alcalina (SAP seguida por solução de 4-nitro-azul de tetrazolio/5-bromo-4-cloro-3-indolil fosfato (NBT/BCIP foram utilizadas para detecção da biotina após a reação de hibridização. Reação positiva foi

Choline PET based dose-painting in prostate cancer - Modelling of dose effects

International Nuclear Information System (INIS)

Niyazi, Maximilian; Bartenstein, Peter; Belka, Claus; Ganswindt, Ute

2010-01-01

Several randomized trials have documented the value of radiation dose escalation in patients with prostate cancer, especially in patients with intermediate risk profile. Up to now dose escalation is usually applied to the whole prostate. IMRT and related techniques currently allow for dose escalation in sub-volumes of the organ. However, the sensitivity of the imaging modality and the fact that small islands of cancer are often dispersed within the whole organ may limit these approaches with regard to a clear clinical benefit. In order to assess potential effects of a dose escalation in certain sub-volumes based on choline PET imaging a mathematical dose-response model was developed. Based on different assumptions for α/β, γ50, sensitivity and specificity of choline PET, the influence of the whole prostate and simultaneous integrated boost (SIB) dose on tumor control probability (TCP) was calculated. Based on the given heterogeneity of all potential variables certain representative permutations of the parameters were chosen and, subsequently, the influence on TCP was assessed. Using schedules with 74 Gy within the whole prostate and a SIB dose of 90 Gy the TCP increase ranged from 23.1% (high detection rate of choline PET, low whole prostate dose, high γ50/ASTRO definition for tumor control) to 1.4% TCP gain (low sensitivity of PET, high whole prostate dose, CN + 2 definition for tumor control) or even 0% in selected cases. The corresponding initial TCP values without integrated boost ranged from 67.3% to 100%. According to a large data set of intermediate-risk prostate cancer patients the resulting TCP gains ranged from 22.2% to 10.1% (ASTRO definition) or from 13.2% to 6.0% (CN + 2 definition). Although a simplified mathematical model was employed, the presented model allows for an estimation in how far given schedules are relevant for clinical practice. However, the benefit of a SIB based on choline PET seems less than intuitively expected. Only under the

Why we need new approaches to low-dose risk modeling

International Nuclear Information System (INIS)

Alvarez, J.L.; Seiler, F.A.

1996-01-01

The linear no-threshold model for radiation effects was introduced as a conservative model for the design of radiation protection programs. The model has persisted not only as the basis for such programs, but has come to be treated as a dogma and is often confused with scientific fact. In this examination a number of serious problems with the linear no-threshold model of radiation carcinogenesis were demonstrated, many of them invalidating the hypothesis. It was shown that the relative risk formalism did not approach 1 as the dose approaches zero. When morality ratios were used instead, the data in the region below 0.3 Sv were systematically below the predictions of the linear model. It was also shown that the data above 0.3 Sv were of little use in formulating a model at low doses. In addition, these data are valid only for doses accumulated at high dose rates, and there is no scientific justification for using the model in low-dose, low-dose-rate extrapolations for purposes of radiation protection. Further examination of model fits to the Japanese survivor data were attempted. Several such models were fit to the data including an unconstrained linear, linear-square root, and Weibull, all of which fit the data better than the relative risk, linear no-threshold model. These fits were used to demonstrate that the linear model systematically over estimates the risk at low doses in the Japanese survivor data set. It is recommended here that an unbiased re-analysis of the data be undertaken and the results used to construct a new model, based on all pertinent data. This model could then form the basis for managing radiation risks in the appropriate regions of dose and dose rate

Histotripsy of the Prostate for the Treatment of BPH: Chronic Results From a Canine Model

Science.gov (United States)

Hall, Timothy L.; Hempel, Chris R.; Lake, Alison M.; Kieran, Kathy; Ives, Kim; Fowlkes, J. Brian; Cain, Charles A.; Roberts, William W.

2009-04-01

Histotripsy was evaluated as a non-invasive BPH treatment. The prostates of 21 canine subjects were targeted with one of three histotripsy doses. Prostates were harvested immediately, 7 days, or 28 days after treatment and assessed for changes. Lower treatment doses were found to produced scattered cellular disruption and hemorrhage that was sometimes reversible. Higher doses perforated the urethra and produced cavities in the glandular prostate that healed to leave an enlarged urinary channel.

Development of the model MAAP5-DOSE for dose analysis in Cofrentes NPP

International Nuclear Information System (INIS)

Gonzalez, C.; Diaz, P.; Ibanez, L.; Lamela, B.; Serrano, C.

2013-01-01

Iberdrola Ingenieria y Construccion has developed a model of Cofrentes NPP with code MAAP5-DOSE in order to be able to assess in realistic conditions the the expected dose in points and radiological consequences of severe accident of local action.

Isobio software: biological dose distribution and biological dose volume histogram from physical dose conversion using linear-quadratic-linear model.

Science.gov (United States)

Jaikuna, Tanwiwat; Khadsiri, Phatchareewan; Chawapun, Nisa; Saekho, Suwit; Tharavichitkul, Ekkasit

2017-02-01

To develop an in-house software program that is able to calculate and generate the biological dose distribution and biological dose volume histogram by physical dose conversion using the linear-quadratic-linear (LQL) model. The Isobio software was developed using MATLAB version 2014b to calculate and generate the biological dose distribution and biological dose volume histograms. The physical dose from each voxel in treatment planning was extracted through Computational Environment for Radiotherapy Research (CERR), and the accuracy was verified by the differentiation between the dose volume histogram from CERR and the treatment planning system. An equivalent dose in 2 Gy fraction (EQD 2 ) was calculated using biological effective dose (BED) based on the LQL model. The software calculation and the manual calculation were compared for EQD 2 verification with pair t -test statistical analysis using IBM SPSS Statistics version 22 (64-bit). Two and three-dimensional biological dose distribution and biological dose volume histogram were displayed correctly by the Isobio software. Different physical doses were found between CERR and treatment planning system (TPS) in Oncentra, with 3.33% in high-risk clinical target volume (HR-CTV) determined by D 90% , 0.56% in the bladder, 1.74% in the rectum when determined by D 2cc , and less than 1% in Pinnacle. The difference in the EQD 2 between the software calculation and the manual calculation was not significantly different with 0.00% at p -values 0.820, 0.095, and 0.593 for external beam radiation therapy (EBRT) and 0.240, 0.320, and 0.849 for brachytherapy (BT) in HR-CTV, bladder, and rectum, respectively. The Isobio software is a feasible tool to generate the biological dose distribution and biological dose volume histogram for treatment plan evaluation in both EBRT and BT.

Dose Assessment Model for Chronic Atmospheric Releases of Tritium

International Nuclear Information System (INIS)

Shen Huifang; Yao Rentai

2010-01-01

An improved dose assessment model for chronic atmospheric releases of tritium was proposed. The proposed model explicitly considered two chemical forms of tritium.It was based on conservative assumption of transfer of tritiated water (HTO) from air to concentration of HTO and organic beam tritium (OBT) in vegetable and animal products.The concentration of tritium in plant products was calculated based on considering dividedly leafy plant and not leafy plant, meanwhile the concentration contribution of tritium in the different plants from the tritium in soil was taken into account.Calculating the concentration of HTO in animal products, average water fraction of animal products and the average weighted tritium concentration of ingested water based on the fraction of water supplied by each source were considered,including skin absorption, inhalation, drinking water and food.Calculating the annual doses, the ingestion doses were considered, at the same time the contribution of inhalation and skin absorption to the dose was considered. Concentrations in foodstuffs and dose of annual adult calculated with the specific activity model, NEWTRI model and the model proposed by the paper were compared. The results indicate that the model proposed by the paper can predict accurately tritium doses through the food chain from chronic atmospheric releases. (authors)

On the possibility of reducing doses received by patients during mammography screening

International Nuclear Information System (INIS)

Tolwinski, J.; Fabiszewska, E.; Gwiazdowska, B.; Bulski, W.

2005-01-01

The aim of the study was to collect and to evaluate a set of data of a large group of patients examined with different mammography units, and to compare the individual doses (Di) with the standard average glandular dose (standard AGD) established for a particular mammography unit. The comparison was intended to allow to formulate recommendations of procedures in order to limit the exposure of patients, procedures which are beyond the scope of routine testing of mammography facilities. The presented analysis bases on the results of the measurements of the standard AGD, taken from 82 protocols of quality control of mammography equipment; - 16 histograms of dose distribution for individual patients (Di) examined with 16 different mammography units; - 2 histograms for patients examined with one mammography unit by the radiographer before and after training; - histograms of individual doses (Di), corresponding high-voltage (kV) and tube-loading (mAs) values, for one mammography unit (Elscint-Glory 2001) which was equipped with an automatic optimisation of contrast (AOC) system. The measurements were carried out according to the procedures of the American College of Radiology (ACR). Basing upon the constructed histograms we performed a comparison of the standard AGD values with the individual doses (Di). The frequency distribution of the standard AGDs (Figure 1) shows a considerable dispersion of values, ranging between 0.5 and 2.5 mGy. The histograms of the individual glandular doses (Di) calculated for individual patients, examined with different units (Figure 2) suggest that the choice of high voltage made by the radiographers may be incorrect i.e. the high voltage was not increased sufficiently with the increase of breast thickness. The incorrect value of the high voltage (low value) may be also set up by the AOC system (Figure 4). Two histograms for patients examined with one mammography unit by the radiographer before and after training (Figure 3) indicate the

American College of Radiology Accreditation Program for mammographic screening sites: Physical evaluation criteria

International Nuclear Information System (INIS)

Hendrick, R.E.; Haus, A.G.; Hubbard, L.B.; Lasky, H.J.; McCrohan, J.; McLelland, R.; Rothenberg, L.N.; Tanner, R.L.; Zinninger, M.D.

1987-01-01

The American College of Radiology has initiated a program for the accreditation of mammographic screening sites, which includes evaluation by mail of image quality and average glandular breast dose. Image quality is evaluated by use of a specially designed phantom (a modified RMI 152D Mammographic Phantom) containing simulated microcalcifications, fibrils and masses. Average glandular dose to a simulated 4.5-cm-thick (50% glandular, 50% fat) compressed breast is evaluated by thermoluminescent dosimeter measurements of entrance exposure and half value layer. Standards for acceptable image quality and patient doses are presented and preliminary results of the accreditation program are discussed

Incidence of late rectal bleeding in high-dose conformal radiotherapy of prostate cancer using equivalent uniform dose-based and dose-volume-based normal tissue complication probability models

International Nuclear Information System (INIS)

Soehn, Matthias; Yan Di; Liang Jian; Meldolesi, Elisa; Vargas, Carlos; Alber, Markus

2007-01-01

Purpose: Accurate modeling of rectal complications based on dose-volume histogram (DVH) data are necessary to allow safe dose escalation in radiotherapy of prostate cancer. We applied different equivalent uniform dose (EUD)-based and dose-volume-based normal tissue complication probability (NTCP) models to rectal wall DVHs and follow-up data for 319 prostate cancer patients to identify the dosimetric factors most predictive for Grade ≥ 2 rectal bleeding. Methods and Materials: Data for 319 patients treated at the William Beaumont Hospital with three-dimensional conformal radiotherapy (3D-CRT) under an adaptive radiotherapy protocol were used for this study. The following models were considered: (1) Lyman model and (2) logit-formula with DVH reduced to generalized EUD (3) serial reconstruction unit (RU) model (4) Poisson-EUD model, and (5) mean dose- and (6) cutoff dose-logistic regression model. The parameters and their confidence intervals were determined using maximum likelihood estimation. Results: Of the patients, 51 (16.0%) showed Grade 2 or higher bleeding. As assessed qualitatively and quantitatively, the Lyman- and Logit-EUD, serial RU, and Poisson-EUD model fitted the data very well. Rectal wall mean dose did not correlate to Grade 2 or higher bleeding. For the cutoff dose model, the volume receiving > 73.7 Gy showed most significant correlation to bleeding. However, this model fitted the data more poorly than the EUD-based models. Conclusions: Our study clearly confirms a volume effect for late rectal bleeding. This can be described very well by the EUD-like models, of which the serial RU- and Poisson-EUD model can describe the data with only two parameters. Dose-volume-based cutoff-dose models performed worse

Mathematical model for evaluation of dose-rate effect on biological responses to low dose γ-radiation

International Nuclear Information System (INIS)

Ogata, H.; Kawakami, Y.; Magae, J.

2003-01-01

Full text: To evaluate quantitative dose-response relationship on the biological response to radiation, it is necessary to consider a model including cumulative dose, dose-rate and irradiation time. In this study, we measured micronucleus formation and [ 3 H] thymidine uptake in human cells as indices of biological response to gamma radiation, and analyzed mathematically and statistically the data for quantitative evaluation of radiation risk at low dose/low dose-rate. Effective dose (ED x ) was mathematically estimated by fitting a general function of logistic model to the dose-response relationship. Assuming that biological response depends on not only cumulative dose but also dose-rate and irradiation time, a multiple logistic function was applied to express the relationship of the three variables. Moreover, to estimate the effect of radiation at very low dose, we proposed a modified exponential model. From the results of fitting curves to the inhibition of [ 3 H] thymidine uptake and micronucleus formation, it was obvious that ED 50 in proportion of inhibition of [ 3 H] thymidine uptake increased with longer irradiation time. As for the micronuclei, ED 30 also increased with longer irradiation times. These results suggest that the biological response depends on not only total dose but also irradiation time. The estimated response surface using the three variables showed that the biological response declined sharply when the dose-rate was less than 0.01 Gy/h. These results suggest that the response does not depend on total cumulative dose at very low dose-rates. Further, to investigate the effect of dose-rate within a wider range, we analyzed the relationship between ED x and dose-rate. Fitted curves indicated that ED x increased sharply when dose-rate was less than 10 -2 Gy/h. The increase of ED x signifies the decline of the response or the risk and suggests that the risk approaches to 0 at infinitely low dose-rate

True dose from incorporated activities. Models for internal dosimetry

International Nuclear Information System (INIS)

Breustedt, B.; Eschner, W.; Nosske, D.

2012-01-01

The assessment of doses after incorporation of radionuclides cannot use direct measurements of the doses, as for example dosimetry in external radiation fields. The only observables are activities in the body or in excretions. Models are used to calculate the doses based on the measured activities. The incorporated activities and the resulting doses can vary by more than seven orders of magnitude between occupational and medical exposures. Nevertheless the models and calculations applied in both cases are similar. Since the models for the different applications have been developed independently by ICRP and MIRD different terminologies have been used. A unified terminology is being developed. (orig.)

Verification of an effective dose equivalent model for neutrons

International Nuclear Information System (INIS)

Tanner, J.E.; Piper, R.K.; Leonowich, J.A.; Faust, L.G.

1992-01-01

Since the effective dose equivalent, based on the weighted sum of organ dose equivalents, is not a directly measurable quantity, it must be estimated with the assistance of computer modelling techniques and a knowledge of the incident radiation field. Although extreme accuracy is not necessary for radiation protection purposes, a few well chosen measurements are required to confirm the theoretical models. Neutron doses and dose equivalents were measured in a RANDO phantom at specific locations using thermoluminescence dosemeters, etched track dosemeters, and a 1.27 cm (1/2 in) tissue-equivalent proportional counter. The phantom was exposed to a bare and a D 2 O-moderated 252 Cf neutron source at the Pacific Northwest Laboratory's Low Scatter Facility. The Monte Carlo code MCNP with the MIRD-V mathematical phantom was used to model the human body and to calculate the organ doses and dose equivalents. The experimental methods are described and the results of the measurements are compared with the calculations. (author)

Molecular cloning and functional characterization of borneol dehydrogenase from the glandular trichomes of Lavandula x intermedia.

Science.gov (United States)

Sarker, Lukman S; Galata, Mariana; Demissie, Zerihun A; Mahmoud, Soheil S

2012-12-15

Several varieties of Lavandula x intermedia (lavandins) are cultivated for their essential oils (EOs) for use in cosmetic, hygiene and personal care products. These EOs are mainly constituted of monoterpenes including camphor, which contributes an off odor reducing the olfactory appeal of the oil. We have recently constructed a cDNA library from the glandular trichomes (the sites of EO synthesis) of L. x intermedia plants. Here, we describe the cloning of a borneol dehydrogenase cDNA (LiBDH) from this library. The 780 bp open reading frame of the cDNA encoded a 259 amino acid short chain alcohol dehydrogenase with a predicted molecular mass of ca. 27.5 kDa. The recombinant LiBDH was expressed in Escherichia coli, purified by Ni-NTA agarose affinity chromatography, and functionally characterized in vitro. The bacterially produced enzyme specifically converted borneol to camphor as the only product with K(m) and k(cat) values of 53 μM and 4.0 × 10(-4) s(-1), respectively. The LiBDH transcripts were specifically expressed in glandular trichomes of mature flowers indicating that like other Lavandula monoterpene synthases the expression of this gene is regulated in a tissue-specific manner. The cloning of LiBDH has far reaching implications in improving the quality of Lavandula EOs through metabolic engineering. Copyright © 2012 Elsevier Inc. All rights reserved.

Model of organ dose combination

International Nuclear Information System (INIS)

Valley, J.-F.; Lerch, P.

1977-01-01

The ICRP recommendations are based on the limitation of the dose to each organ. In the application and for a unique source the critical organ concept allows to limit the calculation and represents the irradiation status of an individuum. When several sources of radiation are involved the derivation of the dose contribution of each source to each organ is necessary. In order to represent the irradiation status a new parameter is to be defined. Propositions have been made by some authors, in particular by Jacobi introducing at this level biological parameters like the incidence rate of detriment and its severity. The new concept is certainly richer than a simple dose notion. However, in the actual situation of knowledge about radiation effects an intermediate parameter, using only physical concepts and the maximum permissible doses to the organs, seems more appropriate. The model, which is a generalization of the critical organ concept and shall be extended in the future to take the biological effects into account, will be presented [fr

Review of the first 50 cases completed by the RACR mammography QA programme; Phantom image quality, processor control and dose considerations

International Nuclear Information System (INIS)

McLean, D.; Chan, W.; Eckert, M.; Heard, R.

1997-01-01

The Mammography Quality Assurance Programme, recently established by the Royal Australasian College of Radiologists, has processed the first 50 applications. This programme, which closely follows the programme of the American College of Radiology (ACR), utilizes phantom film images, thermoluminescent dosimetry measurement of mean glandular dose, processor control charts, clinical images, equipment reports and required survey information to establish that a centre conforms to a minimum standard in mammography. The present paper describes the initial results of the first phantom images, dose measurements, processor control and survey information. Fifty films have been evaluated up to the present time with a failure rate of 26%. The major causes of failure were unacceptable film artefacts and poor contrast (as indicated by reduced fibre and mass visibility). A surprising result was the high failure in processing, where 23% of units reviewed had significant problems, including failure to keep the processor within required control limits. Only one centre recorded a mean glandular dose above 2 mGy with no centre over the 3 mGy limit. A review of the frequency of the quality control testing shows that the acceptance of quality assurance in mammography, while greater than in the initial stages of the ACR programme, is less than current US practice. These initial results for the accreditation process probably reflect an initial period of adjustment, as seen by the high pass rate achieved by centres that have re submitted material to gain accreditation. (authors)

Trend of patient radiation doses in medical examination in Japan

International Nuclear Information System (INIS)

Suzuki, Shoichi

2013-01-01

We have investigated radiation doses to patients in selected types of examinations in Japan since 1974 and have analyzed the trend of patient radiation doses during a period of 37 years. This study covered regular plain X-ray scanning (including mammography) and computed tomography (CT) scanning. Dose evaluation was performed in terms of entrance skin dose (ESD) for regular plain X-ray scanning, average glandular dose (AGD) for mammography, and volume CT dose index (CTDIvol) for CT scanning. Evaluation was performed in 26 orientations at 21 sites for regular plain X-rays, and for cranial, thoracic, and abdominal scans of children and adults for CT scanning. With the exception of chest X-rays, the dose during regular plain X-ray scanning had decreased by approximately 50% compared with scans performed in 1974. The dose during mammography had decreased to less than 10% of its former level. In scans performed in 2011, dose at all sites were within International Atomic Energy Authority (IAEA) guidance levels. The increasing use of multiple detectors in CT scanning devices was evident in CT scanning. A comparison of doses from cranial non-helical scans performed in 2007 and 2011 found that the latter were higher. An examination of changes in doses between 1997 and 2011 revealed that doses had tended to increase in cranial scans of adults, but had hardly changed at all in abdominal scans. Doses during CT scanning of children were around half those for adults in cranial, thoracic, and abdominal scans. We have ascertained changes in the doses to which patients have been exposed during X-ray scanning in Japan. (author)

Verification of an effective dose equivalent model for neutrons

International Nuclear Information System (INIS)

Tanner, J.E.; Piper, R.K.; Leonowich, J.A.; Faust, L.G.

1991-10-01

Since the effective dose equivalent, based on the weighted sum of organ dose equivalents, is not a directly measurable quantity, it must be estimated with the assistance of computer modeling techniques and a knowledge of the radiation field. Although extreme accuracy is not necessary for radiation protection purposes, a few well-chosen measurements are required to confirm the theoretical models. Neutron measurements were performed in a RANDO phantom using thermoluminescent dosemeters, track etch dosemeters, and a 1/2-in. (1.27-cm) tissue equivalent proportional counter in order to estimate neutron doses and dose equivalents within the phantom at specific locations. The phantom was exposed to bare and D 2 O-moderated 252 Cf neutrons at the Pacific Northwest Laboratory's Low Scatter Facility. The Monte Carlo code MCNP with the MIRD-V mathematical phantom was used to model the human body and calculate organ doses and dose equivalents. The experimental methods are described and the results of the measurements are compared to the calculations. 8 refs., 3 figs., 3 tabs

A study to determine the differences between the displayed dose values for two full-field digital mammography units and values calculated using a range of Monte-Carlo-based techniques: A phantom study

International Nuclear Information System (INIS)

Borg, M.; Badr, I.; Royle, G. J.

2013-01-01

Modern full-field digital mammography (FFDM) units display the mean glandular dose (MGD) and the entrance or incident air kerma (K) to the breast following each exposure. Information on how these values are calculated is limited and knowing how displayed MGD values compare and correlate to conventional Monte-Carlo-based methods is useful. From measurements done on polymethyl methacrylate (PMMA) phantoms, it has been shown that displayed and calculated MGD values are similar for thin to medium thicknesses and appear to differ with larger PMMA thicknesses. As a result, a multiple linear regression analysis on the data was performed to generate models by which displayed MGD values on the two FFDM units included in the study may be converted to the Monte-Carlo values calculated by conventional methods. These models should be a useful tool for medical physicists requiring MGD data from FFDM units included in this paper and should reduce the survey time spent on dose calculations. (authors)

Modeling dose-rate on/over the surface of cylindrical radio-models using Monte Carlo methods

International Nuclear Information System (INIS)

Xiao Xuefu; Ma Guoxue; Wen Fuping; Wang Zhongqi; Wang Chaohui; Zhang Jiyun; Huang Qingbo; Zhang Jiaqiu; Wang Xinxing; Wang Jun

2004-01-01

Objective: To determine the dose-rates on/over the surface of 10 cylindrical radio-models, which belong to the Metrology Station of Radio-Geological Survey of CNNC. Methods: The dose-rates on/over the surface of 10 cylindrical radio-models were modeled using the famous Monte Carlo code-MCNP. The dose-rates on/over the surface of 10 cylindrical radio-models were measured by a high gas pressurized ionization chamber dose-rate meter, respectively. The values of dose-rate modeled using MCNP code were compared with those obtained by authors in the present experimental measurement, and with those obtained by other workers previously. Some factors causing the discrepancy between the data obtained by authors using MCNP code and the data obtained using other methods are discussed in this paper. Results: The data of dose-rates on/over the surface of 10 cylindrical radio-models, obtained using MCNP code, were in good agreement with those obtained by other workers using the theoretical method. They were within the discrepancy of ±5% in general, and the maximum discrepancy was less than 10%. Conclusions: As if each factor needed for the Monte Carlo code is correct, the dose-rates on/over the surface of cylindrical radio-models modeled using the Monte Carlo code are correct with an uncertainty of 3%

Biosphere model for assessing doses from nuclear waste disposal

International Nuclear Information System (INIS)

Zach, R.; Amiro, B.D.; Davis, P.A.; Sheppard, S.C.; Szekeley, J.G.

1994-01-01

The biosphere model, BIOTRAC, for predicting long term nuclide concentrations and radiological doses from Canada's nuclear fuel waste disposal concept of a vault deep in plutonic rock of the Canadian Shield is presented. This generic, boreal zone biosphere model is based on scenario analysis and systems variability analysis using Monte Carlo simulation techniques. Conservatism is used to bridge uncertainties, even though this creates a small amount of extra nuclide mass. Environmental change over the very long assessment period is mainly handled through distributed parameter values. The dose receptors are a critical group of humans and four generic non-human target organisms. BIOTRAC includes six integrated submodels and it interfaces smoothly with a geosphere model. This interface includes a bedrock well. The geosphere model defines the discharge zones of deep groundwater where nuclides released from the vault enter the biosphere occupied by the dose receptors. The size of one of these zones is reduced when water is withdrawn from the bedrock well. Sensitivity analysis indicates 129 I is by far the most important radionuclide. Results also show bedrock-well water leads to higher doses to man than lake water, but the former doses decrease with the size of the critical group. Under comparable circumstances, doses to the non-human biota are greater than those for man

Dosimetry and image quality assessment in a direct radiography system

Energy Technology Data Exchange (ETDEWEB)

Oliveira, Bruno Beraldo; Paixao, Lucas; Nogueira, Maria do Socorro, E-mail: boliveira.mg@gmail.com [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil); Oliveira, Marcio Alves de [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Fac. de Medicina. Dept. de Anatomia e Imagem; Teixeira, Maria Helena Araujo [Clinica Dra. Maria Helena Araujo Teixeira, Belo Horizonte, MG (Brazil)

2014-11-15

Objective: to evaluate the mean glandular dose with a solid state detector and the image quality in a direct radiography system, utilizing phantoms. Materials and methods: Irradiations were performed with automatic exposure control and polymethyl methacrylate slabs with different thicknesses to calculate glandular dose values. The image quality was evaluated by means of the structures visualized on the images of the phantoms. Results: considering the uncertainty of the measurements, the mean glandular dose results are in agreement with the values provided by the equipment and with internationally adopted reference levels. Results obtained from images of the phantoms were in agreement with the reference values. Conclusion: the present study contributes to verify the equipment conformity as regards dose values and image quality. (author)

NAIRAS aircraft radiation model development, dose climatology, and initial validation.

Science.gov (United States)

Mertens, Christopher J; Meier, Matthias M; Brown, Steven; Norman, Ryan B; Xu, Xiaojing

2013-10-01

[1] The Nowcast of Atmospheric Ionizing Radiation for Aviation Safety (NAIRAS) is a real-time, global, physics-based model used to assess radiation exposure to commercial aircrews and passengers. The model is a free-running physics-based model in the sense that there are no adjustment factors applied to nudge the model into agreement with measurements. The model predicts dosimetric quantities in the atmosphere from both galactic cosmic rays (GCR) and solar energetic particles, including the response of the geomagnetic field to interplanetary dynamical processes and its subsequent influence on atmospheric dose. The focus of this paper is on atmospheric GCR exposure during geomagnetically quiet conditions, with three main objectives. First, provide detailed descriptions of the NAIRAS GCR transport and dosimetry methodologies. Second, present a climatology of effective dose and ambient dose equivalent rates at typical commercial airline altitudes representative of solar cycle maximum and solar cycle minimum conditions and spanning the full range of geomagnetic cutoff rigidities. Third, conduct an initial validation of the NAIRAS model by comparing predictions of ambient dose equivalent rates with tabulated reference measurement data and recent aircraft radiation measurements taken in 2008 during the minimum between solar cycle 23 and solar cycle 24. By applying the criterion of the International Commission on Radiation Units and Measurements (ICRU) on acceptable levels of aircraft radiation dose uncertainty for ambient dose equivalent greater than or equal to an annual dose of 1 mSv, the NAIRAS model is within 25% of the measured data, which fall within the ICRU acceptable uncertainty limit of 30%. The NAIRAS model predictions of ambient dose equivalent rate are generally within 50% of the measured data for any single-point comparison. The largest differences occur at low latitudes and high cutoffs, where the radiation dose level is low. Nevertheless, analysis

NAIRAS aircraft radiation model development, dose climatology, and initial validation

Science.gov (United States)

Mertens, Christopher J.; Meier, Matthias M.; Brown, Steven; Norman, Ryan B.; Xu, Xiaojing

2013-10-01

The Nowcast of Atmospheric Ionizing Radiation for Aviation Safety (NAIRAS) is a real-time, global, physics-based model used to assess radiation exposure to commercial aircrews and passengers. The model is a free-running physics-based model in the sense that there are no adjustment factors applied to nudge the model into agreement with measurements. The model predicts dosimetric quantities in the atmosphere from both galactic cosmic rays (GCR) and solar energetic particles, including the response of the geomagnetic field to interplanetary dynamical processes and its subsequent influence on atmospheric dose. The focus of this paper is on atmospheric GCR exposure during geomagnetically quiet conditions, with three main objectives. First, provide detailed descriptions of the NAIRAS GCR transport and dosimetry methodologies. Second, present a climatology of effective dose and ambient dose equivalent rates at typical commercial airline altitudes representative of solar cycle maximum and solar cycle minimum conditions and spanning the full range of geomagnetic cutoff rigidities. Third, conduct an initial validation of the NAIRAS model by comparing predictions of ambient dose equivalent rates with tabulated reference measurement data and recent aircraft radiation measurements taken in 2008 during the minimum between solar cycle 23 and solar cycle 24. By applying the criterion of the International Commission on Radiation Units and Measurements (ICRU) on acceptable levels of aircraft radiation dose uncertainty for ambient dose equivalent greater than or equal to an annual dose of 1 mSv, the NAIRAS model is within 25% of the measured data, which fall within the ICRU acceptable uncertainty limit of 30%. The NAIRAS model predictions of ambient dose equivalent rate are generally within 50% of the measured data for any single-point comparison. The largest differences occur at low latitudes and high cutoffs, where the radiation dose level is low. Nevertheless, analysis suggests

Toward a unified approach to dose-response modeling in ecotoxicology.

Science.gov (United States)

Ritz, Christian

2010-01-01

This study reviews dose-response models that are used in ecotoxicology. The focus lies on clarification of differences and similarities between models, and as a side effect, their different guises in ecotoxicology are unravelled. A look at frequently used dose-response models reveals major discrepancies, among other things in naming conventions. Therefore, there is a need for a unified view on dose-response modeling in order to improve the understanding of it and to facilitate communication and comparison of findings across studies, thus realizing its full potential. This study attempts to establish a general framework that encompasses most dose-response models that are of interest to ecotoxicologists in practice. The framework includes commonly used models such as the log-logistic and Weibull models, but also features entire suites of models as found in various guidance documents. An outline on how the proposed framework can be implemented in statistical software systems is also provided.

Clinical implications of alternative TCP models for nonuniform dose distributions

International Nuclear Information System (INIS)

Deasy, J. O.

1995-01-01

Several tumor control probability (TCP) models for nonuniform dose distributions were compared, including: (a) a logistic/inter-patient-heterogeneity model, (b) a probit/inter-patient-heterogeneity model, (c) a Poisson/radioresistant-strain/identical-patients model, (d) a Poisson/inter-patient-heterogeneity model and (e) a Poisson/intra-tumor- and inter-patient-heterogeneity model. The models were analyzed in terms of the probability of controlling a single tumor voxel (the voxel control probability, or VCP), as a function of voxel volume and dose. Alternatively, the VCP surface can be thought of as the effect of a small cold spot. The models based on the Poisson equation which include inter-patient heterogeneity ((d) and (e)) have VCP surfaces (VCP as a function of dose and volume) which have a threshold 'waterfall' shape: below the waterfall (in dose), VCP is nearly zero. The threshold dose decreases with decreasing voxel volume. However, models (a), (b), and (c) all show a high probability of controlling a voxel (VCP>50%) with very low dose (e.g., 1 Gy) if the voxel is small (smaller than about 10 -3 of the tumor volume). Model (c) does not have the waterfall shape at low volumes due to the assumption of patient uniformity and a neglect of the effect of the clonogens which are more radiosensitive (and more numerous). Models (a) and (b) deviate from the waterfall shape at low volumes due to numerical differences between the functions used and the Poisson function. Hence, the Possion models which include inter-patient heterogeneities ((d) and (e)) are more sensitive to the effects of small cold spots than the other models considered

Recommendations on dose buildup factors used in models for calculating gamma doses for a plume

International Nuclear Information System (INIS)

Hedemann Jensen, P.; Thykier-Nielsen, S.

1980-09-01

Calculations of external γ-doses from radioactivity released to the atmosphere have been made using different dose buildup factor formulas. Some of the dose buildup factor formulas are used by the Nordic countries in their respective γ-dose models. A comparison of calculated γ-doses using these dose buildup factors shows that the γ-doses can be significantly dependent on the buildup factor formula used in the calculation. Increasing differences occur for increasing plume height, crosswind distance, and atmospheric stability and also for decreasing downwind distance. It is concluded that the most accurate γ-dose can be calculated by use of Capo's polynomial buildup factor formula. Capo-coefficients have been calculated and shown in this report for γ-energies below the original lower limit given by Capo. (author)

A model for inverse dose-rate effects - low dose-rate hyper-sensibility in response to targeted radionuclide therapy

International Nuclear Information System (INIS)

Murray, I.; Mather, S.J.

2015-01-01

Full text of publication follows. The aim of this work was to test the hypothesis that the Linear-Quadratic (LQ) model of cell survival, developed for external beam radiotherapy (EBRT), could be extended to targeted radionuclide therapy (TRT) in order to predict dose-response relationships in a cell line exhibiting low dose hypersensitivity (LDH). Methods: aliquots of the PC-3 cancer cell line were treated with either EBRT or an in-vitro model of TRT (Irradiation of cell culture with Y-90 EDTA over 24, 48, 72 or 96 hours). Dosimetry for the TRT was calculated using radiation transport simulations with the Monte Carlo PENELOPE code. Clonogenic as well as functional biological assays were used to assess cell response. An extension of the LQ model was developed which incorporated a dose-rate threshold for activation of repair mechanisms. Results: accurate dosimetry for in-vitro exposures of cell cultures to radioactivity was established. LQ parameters of cell survival were established for the PC-3 cell line in response to EBRT. The standard LQ model did not predict survival in PC-3 cells exposed to Y 90 irradiation over periods of up to 96 hours. In fact cells were more sensitive to the same dose when irradiation was carried out over 96 hours than 24 hours. I.e. at a lower dose-rate. Deviations from the LQ predictions were most pronounced below a threshold dose-rate of 0.5 Gy/hr. These results led to an extension of the LQ model based upon a dose-rate dependent sigmoid model of single strand DNA repair. This extension to the model resulted in predicted cell survival curves that closely matched the experimental data. Conclusion: the LQ model of cell survival to radiation has been shown to be largely predictive of response to low dose-rate irradiation. However, in cells displaying LDH, further adaptation of the model was required. (authors)

Monte Carlo derivation of filtered tungsten anode X-ray spectra for dose computation in digital mammography*

Science.gov (United States)

Paixão, Lucas; Oliveira, Bruno Beraldo; Viloria, Carolina; de Oliveira, Marcio Alves; Teixeira, Maria Helena Araújo; Nogueira, Maria do Socorro

2015-01-01

Objective Derive filtered tungsten X-ray spectra used in digital mammography systems by means of Monte Carlo simulations. Materials and Methods Filtered spectra for rhodium filter were obtained for tube potentials between 26 and 32 kV. The half-value layer (HVL) of simulated filtered spectra were compared with those obtained experimentally with a solid state detector Unfors model 8202031-H Xi R/F & MAM Detector Platinum and 8201023-C Xi Base unit Platinum Plus w mAs in a Hologic Selenia Dimensions system using a direct radiography mode. Results Calculated HVL values showed good agreement as compared with those obtained experimentally. The greatest relative difference between the Monte Carlo calculated HVL values and experimental HVL values was 4%. Conclusion The results show that the filtered tungsten anode X-ray spectra and the EGSnrc Monte Carlo code can be used for mean glandular dose determination in mammography. PMID:26811553

Monte Carlo derivation of filtered tungsten anode X-ray spectra for dose computation in digital mammography

Directory of Open Access Journals (Sweden)

Lucas Paixão

2015-12-01

Full Text Available Abstract Objective: Derive filtered tungsten X-ray spectra used in digital mammography systems by means of Monte Carlo simulations. Materials and Methods: Filtered spectra for rhodium filter were obtained for tube potentials between 26 and 32 kV. The half-value layer (HVL of simulated filtered spectra were compared with those obtained experimentally with a solid state detector Unfors model 8202031-H Xi R/F & MAM Detector Platinum and 8201023-C Xi Base unit Platinum Plus w mAs in a Hologic Selenia Dimensions system using a direct radiography mode. Results: Calculated HVL values showed good agreement as compared with those obtained experimentally. The greatest relative difference between the Monte Carlo calculated HVL values and experimental HVL values was 4%. Conclusion: The results show that the filtered tungsten anode X-ray spectra and the EGSnrc Monte Carlo code can be used for mean glandular dose determination in mammography.

Development on Dose Assessment Model of Northeast Asia Nuclear Accident Simulator

Energy Technology Data Exchange (ETDEWEB)

Kim, Ju Yub; Kim, Ju Youl; Kim, Suk Hoon; Lee, Seung Hee; Yoon, Tae Bin [FNC Techology, Yongin (Korea, Republic of)

2016-05-15

In order to support the emergency response system, the simulator for overseas nuclear accident is under development including source-term estimation, atmospheric dispersion modeling and dose assessment. The simulator is named NANAS (Northeast Asia Nuclear Accident Simulator). For the source-term estimation, design characteristics of each reactor type should be reflected into the model. Since there are a lot of reactor types in neighboring countries, the representative reactors of China, Japan and Taiwan have been selected and the source-term estimation models for each reactor have been developed, respectively. For the atmospheric dispersion modeling, Lagrangian particle model will be integrated into the simulator for the long range dispersion modeling in Northeast Asia region. In this study, the dose assessment model has been developed considering external and internal exposure. The dose assessment model has been developed as a part of the overseas nuclear accidents simulator which is named NANAS. It addresses external and internal pathways including cloudshine, groundshine and inhalation. Also, it uses the output of atmospheric dispersion model (i.e. the average concentrations of radionuclides in air and ground) and various coefficients (e.g. dose conversion factor and breathing rate) as an input. Effective dose and thyroid dose for each grid in the Korean Peninsula region are printed out as a format of map projection and chart. Verification and validation on the dose assessment model will be conducted in further study by benchmarking with the measured data of Fukushima Daiichi Nuclear Accident.

Trans-nipple removal of fibro-glandular tissue in gynaecomastia surgery without additional scars: An innovative approach

Directory of Open Access Journals (Sweden)

R K Mishra

2014-01-01

Full Text Available Context: The established techniques that have been used to treat gynaecomastia are said to have relatively less patient satisfaction rate as they leave some visible scars or mild elevation over the nipple areola complex, resulting in aesthetically unsatisfactory results. Even the slightest elevation or smallest scar over nipple areola complex leave patients extremely self conscious and in a dilemma of having a second intervention to get rid of that blemish. Aims: The aim of the study is to achieve - A flat chest without adding a scar and with no chances of re-occurrence of the condition. This article suggests an innovative approach to address the problem. Materials and Methods: The author presents trans-nipple incision approach for the delivery of fibro-glandular tissue component following liposuction for maximum patient satisfaction. This method consists of a unique small criss-cross incision right on the nipple itself for retrieving any volume of tough fibro-glandular tissues. Between the duration of January 2012 to October 2013, 28 male patients of different ages were operated with this technique. Results: The surgery resulted in well-shaped, symmetric chest contour without any visible elevation or additional scars on nipple areola complex. No complications were noticed in any of the patients. Conclusions: The presented technique is proved to have a high patient satisfaction rate and to be promising method to achieve good aesthetic results in gynaecomastia surgery.

Interactive Rapid Dose Assessment Model (IRDAM): user's guide

International Nuclear Information System (INIS)

Poeton, R.W.; Moeller, M.P.; Laughlin, G.J.; Desrosiers, A.E.

1983-05-01

As part of the continuing emphasis on emergency preparedness the US Nuclear Regulatory Commission (NRC) sponsored the development of a rapid dose assessment system by Pacific Northwest Laboratory (PNL). This system, the Interactive Rapid Dose Assessment Model (IRDAM) is a micro-computer based program for rapidly assessing the radiological impact of accidents at nuclear power plants. This User's Guide provides instruction in the setup and operation of the equipment necessary to run IRDAM. Instructions are also given on how to load the magnetic disks and access the interactive part of the program. Two other companion volumes to this one provide additional information on IRDAM. Reactor Accident Assessment Methods (NUREG/CR-3012, Volume 2) describes the technical bases for IRDAM including methods, models and assumptions used in calculations. Scenarios for Comparing Dose Assessment Models (NUREG/CR-3012, Volume 3) provides the results of calculations made by IRDAM and other models for specific accident scenarios

Influence on dose coefficients for workers of the new metabolic models

International Nuclear Information System (INIS)

Gomez Parada, I.M.; Rojo, A.M.

1998-01-01

The International Commission on Radiological Protection (ICRP) has recently reviewed the biokinetic models used in the internal contamination dose assessment. ICRP has adopted a new model for the human respiratory tract and has updated, in ICRP Publications 56, 67 and 69, some of the biokinetic models of ICRP Publication 30. In this paper, the dose coefficients for some selected radionuclides issued in ICRP Publication 68 are compared with those obtained using the software LUPED (LUng Dose Evaluation Program). The former were calculated using the new systemic models, while the latter are based on the old metabolic models. The aim is to know to what extent the new models for systematic retention influence the dose coefficients for workers. (author) [es

Entomology contribution in animal immunity: Determination of the crude thoraxial glandular protein extract of Stomoxys calcitrans as an antibody production enhancer in young horses

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L. Rumokoy

2017-12-01

Full Text Available This experiment was conducted to evaluate the level of antigens protein contained in the crude thoraxial glandular protein (TGP extract of Stomoxys calcitrans which function as immunity enhancer in young horses. The detection of protein content of the thoraxial glandular samples was performed by using a spectrophotometer Nano Drop-1000. This result showed that the lowest level of antigen protein was 0.54 mg/mL, the highest was 72 mg/mL, and the average was 0.675 mg/mL. Six foals were used and divided into two groups. The first group was treated with a solution of 100 μg of TGP by subcutaneous injection, the other group acted as control. The TGP extract was injected on the first day of the experiment. Three ml of blood were sampled from the jugular vein on the 14th day after TGP injection. The blood sampled was centrifuged and its serum placed in micro-tubes to observe the IgG level. The injection of TGP had a significant effect on the IgG level of the experiment animals (P<0.05. This experiment emphasized an important relation between entomology and animal husbandry; health improvement in the young animals was observed after the injection of the insect antigen, so it can be concluded that crude thoraxial glandular proteins of S. calcitrans can be used to improve the immunoglobulin-G circulation in foals.

An improved analytical model for CT dose simulation with a new look at the theory of CT dose

International Nuclear Information System (INIS)

Dixon, Robert L.; Munley, Michael T.; Bayram, Ersin

2005-01-01

Gagne [Med. Phys. 16, 29-37 (1989)] has previously described a model for predicting the sensitivity and dose profiles in the slice-width (z) direction for CT scanners. The model, developed prior to the advent of multidetector CT scanners, is still widely used; however, it does not account for the effect of anode tilt on the penumbra or include the heel effect, both of which are increasingly important for the wider beams (up to 40 mm) of contemporary, multidetector scanners. Additionally, it applied only on (or near) the axis of rotation, and did not incorporate the photon energy spectrum. The improved model described herein transcends all of the aforementioned limitations of the Gagne model, including extension to the peripheral phantom axes. Comparison of simulated and measured dose data provides experimental validation of the model, including verification of the superior match to the penumbra provided by the tilted-anode model, as well as the observable effects on the cumulative dose distribution. The initial motivation for the model was to simulate the quasiperiodic dose distribution on the peripheral, phantom axes resulting from a helical scan series in order to facilitate the implementation of an improved method of CT dose measurement utilizing a short ion chamber, as proposed by Dixon [Med. Phys. 30, 1272-1280 (2003)]. A more detailed set of guidelines for implementing such measurements is also presented in this paper. In addition, some fundamental principles governing CT dose which have not previously been clearly enunciated follow from the model, and a fundamental (energy-based) quantity dubbed 'CTDI-aperture' is introduced

Dose-response relationships for environmentally mediated infectious disease transmission models.

Directory of Open Access Journals (Sweden)

Andrew F Brouwer

2017-04-01

Full Text Available Environmentally mediated infectious disease transmission models provide a mechanistic approach to examining environmental interventions for outbreaks, such as water treatment or surface decontamination. The shift from the classical SIR framework to one incorporating the environment requires codifying the relationship between exposure to environmental pathogens and infection, i.e. the dose-response relationship. Much of the work characterizing the functional forms of dose-response relationships has used statistical fit to experimental data. However, there has been little research examining the consequences of the choice of functional form in the context of transmission dynamics. To this end, we identify four properties of dose-response functions that should be considered when selecting a functional form: low-dose linearity, scalability, concavity, and whether it is a single-hit model. We find that i middle- and high-dose data do not constrain the low-dose response, and different dose-response forms that are equally plausible given the data can lead to significant differences in simulated outbreak dynamics; ii the choice of how to aggregate continuous exposure into discrete doses can impact the modeled force of infection; iii low-dose linear, concave functions allow the basic reproduction number to control global dynamics; and iv identifiability analysis offers a way to manage multiple sources of uncertainty and leverage environmental monitoring to make inference about infectivity. By applying an environmentally mediated infectious disease model to the 1993 Milwaukee Cryptosporidium outbreak, we demonstrate that environmental monitoring allows for inference regarding the infectivity of the pathogen and thus improves our ability to identify outbreak characteristics such as pathogen strain.

Integration of models for the Hanford Environmental Dose Reconstruction Project

International Nuclear Information System (INIS)

Napier, B.A.

1991-01-01

The objective of the Hanford Environmental Dose Reconstruction Project is to estimate the radiation dose that individuals could have received as a result of emissions from nuclear operations at Hanford since 1944. The objective of phase 1 of the project was to demonstrate through calculations that adequate models and support data exist or could be developed to allow realistic estimations of doses to individuals from releases of radionuclides to the environment that occurred as long as 45 years ago. Much of the data used in phase 1 was preliminary; therefore, the doses calculated must be considered preliminary approximations. This paper describes the integration of various models that was implemented for initial computer calculations. Models were required for estimating the quantity of radioactive material released, for evaluating its transport through the environment, for estimating human exposure, and for evaluating resultant doses

Simplification of an MCNP model designed for dose rate estimation

Science.gov (United States)

Laptev, Alexander; Perry, Robert

2017-09-01

A study was made to investigate the methods of building a simplified MCNP model for radiological dose estimation. The research was done using an example of a complicated glovebox with extra shielding. The paper presents several different calculations for neutron and photon dose evaluations where glovebox elements were consecutively excluded from the MCNP model. The analysis indicated that to obtain a fast and reasonable estimation of dose, the model should be realistic in details that are close to the tally. Other details may be omitted.

Object-oriented process dose modeling for glovebox operations

International Nuclear Information System (INIS)

Boerigter, S.T.; Fasel, J.H.; Kornreich, D.E.

1999-01-01

The Plutonium Facility at Los Alamos National Laboratory supports several defense and nondefense-related missions for the country by performing fabrication, surveillance, and research and development for materials and components that contain plutonium. Most operations occur in rooms with one or more arrays of gloveboxes connected to each other via trolley gloveboxes. Minimizing the effective dose equivalent (EDE) is a growing concern as a result of steadily declining allowable dose limits being imposed and a growing general awareness of safety in the workplace. In general, the authors discriminate three components of a worker's total EDE: the primary EDE, the secondary EDE, and background EDE. A particular background source of interest is the nuclear materials vault. The distinction between sources inside and outside of a particular room is arbitrary with the underlying assumption that building walls and floors provide significant shielding to justify including sources in other rooms in the background category. Los Alamos has developed the Process Modeling System (ProMoS) primarily for performing process analyses of nuclear operations. ProMoS is an object-oriented, discrete-event simulation package that has been used to analyze operations at Los Alamos and proposed facilities such as the new fabrication facilities for the Complex-21 effort. In the past, crude estimates of the process dose (the EDE received when a particular process occurred), room dose (the EDE received when a particular process occurred in a given room), and facility dose (the EDE received when a particular process occurred in the facility) were used to obtain an integrated EDE for a given process. Modifications to the ProMoS package were made to utilize secondary dose information to use dose modeling to enhance the process modeling efforts

Dosimetric characterization and organ dose assessment in digital breast tomosynthesis: Measurements and Monte Carlo simulations using voxel phantoms

Energy Technology Data Exchange (ETDEWEB)

Baptista, Mariana, E-mail: marianabaptista@ctn.ist.utl.pt; Di Maria, Salvatore; Barros, Sílvia; Vaz, Pedro [Centro de Ciências e Tecnologias Nucleares, Instituto Superior Técnico, Universidade de Lisboa, Estrada Nacional 10, km 139,7, Bobadela LRS 2695-066 (Portugal); Figueira, Catarina [Centre for Plasma Physics, School of Mathematics and Physics, Queen’s University, Belfast BT7 1NN (United Kingdom); Sarmento, Marta; Orvalho, Lurdes [Serviço de Imagiologia, Hospital da Luz, Avenida Lusíada, 100, Lisboa 1500-650 (Portugal)

2015-07-15

Purpose: Due to its capability to more accurately detect deep lesions inside the breast by removing the effect of overlying anatomy, digital breast tomosynthesis (DBT) has the potential to replace the standard mammography technique in clinical screening exams. However, the European Guidelines for DBT dosimetry are still a work in progress and there are little data available on organ doses other than to the breast. It is, therefore, of great importance to assess the dosimetric performance of DBT with respect to the one obtained with standard digital mammography (DM) systems. The aim of this work is twofold: (i) to study the dosimetric properties of a combined DBT/DM system (MAMMOMAT Inspiration Siemens{sup ®}) for a tungsten/rhodium (W/Rh) anode/filter combination and (ii) to evaluate organs doses during a DBT examination. Methods: For the first task, measurements were performed in manual and automatic exposure control (AEC) modes, using two homogeneous breast phantoms: a PMMA slab phantom and a 4 cm thick breast-shaped rigid phantom, with 50% of glandular tissue in its composition. Monte Carlo (MC) simulations were performed using Monte Carlo N-Particle eXtended v.2.7.0. A MC model was implemented to mimic DM and DBT acquisitions for a wide range of x-ray spectra (24 –34 kV). This was used to calculate mean glandular dose (MGD) and to compute series of backscatter factors (BSFs) that could be inserted into the DBT dosimetric formalism proposed by Dance et al. Regarding the second aim of the study, the implemented MC model of the clinical equipment, together with a female voxel phantom (“Laura”), was used to calculate organ doses considering a typical DBT acquisition. Results were compared with a standard two-view mammography craniocaudal (CC) acquisition. Results: Considering the AEC mode, the acquisition of a single CC view results in a MGD ranging from 0.53 ± 0.07 mGy to 2.41 ± 0.31 mGy in DM mode and from 0.77 ± 0.11 mGy to 2.28 ± 0.32 mGy in DBT mode

Image Quality and Patient Dose Optimisation in Mammography in Slovakia

International Nuclear Information System (INIS)

Horvathova, M.; Nikodemova, D.; Prikazska, M.

2003-01-01

Breast cancer represents also in Slovakia the greatest cancer risk for women, with great incidence and mortality. Conventional film-screen mammography is still the primary breast imaging modality with increasing number of mammography units and mammography examinations. From the radiation protection point of view achievement of good practice in mammography department by implementation of quality assurance play an important role for reduction of patients doses. Introduction of QA needs trained and experienced staff and requires close collaboration between radiologists, medical physicist and radiographers. At the beginning of nineties at the Institute of Preventive and Clinical Medicine we started with a survey of mean glandular doses at 15 existing mammography units in the country. On the basis of a questionnaire in the year 1991 were performed 10 488 mammography examinations, where due to out of date mammography units the mean glandular dose reached more as 3 mGy. In the following years the claim to the modern mammography units kept growing and in the year 1999 the total number of 63 mammography units were operating in Slovakia providing about 101 471 mammography examinations. According to the alarming increase of the number of mammography examinations it is absolutely necessary to work out criteria and principles for Quality Control at mammography workplaces in our country and make it obligatory for the staff of all mammography units. Summarising the CRP results it can be stated that they: 1) Initiated the suggestion of unified QA/QC criteria in mammography and the urgent need to implement them into the national program of radiology image quality improvement; 2) Remitted on unhomogenity not only in the equipment outfit but also in the procedure of evaluation of the measured parameters and imaging quality; 3) Revealed the shortcomings in the everyday practice of mammography units which can be removed only by comprehensive by training of personal in imaging radiology

Noise and dose modeling for pediatric CT optimization: preliminary results

International Nuclear Information System (INIS)

Miller Clemente, Rafael A.; Perez Diaz, Marlen; Mora Reyes, Yudel; Rodriguez Garlobo, Maikel; Castillo Salazar, Rafael

2008-01-01

Full text: A Multiple Linear Regression Model was developed to predict noise and dose in computed tomography pediatric imaging for head and abdominal examinations. Relative values of Noise and Volumetric Computed Tomography Dose Index was used to estimate de model respectively. 54 images of physical phantoms were performed. Independent variables considered included: phantom diameter, tube current and kilovolts, x ray beam collimation, reconstruction diameter and equipment's post processing filters. Predicted values show good agreement with measurements, which were better in noise model (R 2 adjusted =0.953) than the dose model (R 2 adjusted =0.744). Tube current, object diameter, beam collimation and reconstruction filter were identified as the most influencing factors in models. (author)

Simplification of an MCNP model designed for dose rate estimation

Directory of Open Access Journals (Sweden)

Laptev Alexander

2017-01-01

Full Text Available A study was made to investigate the methods of building a simplified MCNP model for radiological dose estimation. The research was done using an example of a complicated glovebox with extra shielding. The paper presents several different calculations for neutron and photon dose evaluations where glovebox elements were consecutively excluded from the MCNP model. The analysis indicated that to obtain a fast and reasonable estimation of dose, the model should be realistic in details that are close to the tally. Other details may be omitted.

Theory of thermoluminescence gamma dose response: The unified interaction model

International Nuclear Information System (INIS)

Horowitz, Y.S.

2001-01-01

We describe the development of a comprehensive theory of thermoluminescence (TL) dose response, the unified interaction model (UNIM). The UNIM is based on both radiation absorption stage and recombination stage mechanisms and can describe dose response for heavy charged particles (in the framework of the extended track interaction model - ETIM) as well as for isotropically ionising gamma rays and electrons (in the framework of the TC/LC geminate recombination model) in a unified and self-consistent conceptual and mathematical formalism. A theory of optical absorption dose response is also incorporated in the UNIM to describe the radiation absorption stage. The UNIM is applied to the dose response supralinearity characteristics of LiF:Mg,Ti and is especially and uniquely successful in explaining the ionisation density dependence of the supralinearity of composite peak 5 in TLD-100. The UNIM is demonstrated to be capable of explaining either qualitatively or quantitatively all of the major features of TL dose response with many of the variable parameters of the model strongly constrained by ancilliary optical absorption and sensitisation measurements

A comparison of dose-response models for death from hematological depression

International Nuclear Information System (INIS)

Morris, M.D.; Jones, T.D.

1987-01-01

Many radiation-induced lethality experiments that have been published for various mammalian species have been compiled into a database suitable to study interspecific variability of radiosensitivity, dose-rate dependence of sensitivity, dose-response behavior within each experiment, etc. The data compiled were restricted to continuous and nearly continuous exposures to photon radiations having source energies above 100 keV. Also, photon source energy, exposure geometry, and body weight considerations were used to select studies where the dose to hematopoietic marrow was nearly uniform, i.e., < +- 20%. The data base reflects 13 mammalian test species ranging from mouse to cattle. Some 211 studies were compiled but only 105 were documented in adequate detail to be useful in development and evaluation of dose-response models of interest to practical human exposures. Of the 105 studies, 70 were for various rodent species, and 35 were for nonrodent groups ranging from standard laboratory primates (body weight ∼5 kg) to cattle (body weight 375 kg). This paper considers seven different dose-response models which are tested for validity against those 105 studies. The dose-response models included: a right-skewed extreme value, a left-skewed extreme value model, log-logistic, log-probit, logistic, probit, and Weibull models. In general, the log transformed models did not improve model performance and the extreme value models did not seem consistent with the preponderance of the data. Overall, the probit and the logistic models seemed preferable over the Weibull model. 30 refs., 8 tabs

Development of a patient-specific two-compartment anthropomorphic breast phantom

International Nuclear Information System (INIS)

Prionas, Nicolas D; Burkett, George W; McKenney, Sarah E; Chen, Lin; Boone, John M; Stern, Robin L

2012-01-01

The purpose of this paper is to develop a technique for the construction of a two-compartment anthropomorphic breast phantom specific to an individual patient's pendant breast anatomy. Three-dimensional breast images were acquired on a prototype dedicated breast computed tomography (bCT) scanner as part of an ongoing IRB-approved clinical trial of bCT. The images from the breast of a patient were segmented into adipose and glandular tissue regions and divided into 1.59 mm thick breast sections to correspond to the thickness of polyethylene stock. A computer-controlled water-jet cutting machine was used to cut the outer breast edge and the internal regions corresponding to glandular tissue from the polyethylene. The stack of polyethylene breast segments was encased in a thermoplastic ‘skin’ and filled with water. Water-filled spaces modeled glandular tissue structures and the surrounding polyethylene modeled the adipose tissue compartment. Utility of the phantom was demonstrated by inserting 200 µm microcalcifications as well as by measuring point dose deposition during bCT scanning. Affine registration of the original patient images with bCT images of the phantom showed similar tissue distribution. Linear profiles through the registered images demonstrated a mean coefficient of determination (r 2 ) between grayscale profiles of 0.881. The exponent of the power law describing the anatomical noise power spectrum was identical in the coronal images of the patient's breast and the phantom. Microcalcifications were visualized in the phantom at bCT scanning. The real-time air kerma rate was measured during bCT scanning and fluctuated with breast anatomy. On average, point dose deposition was 7.1% greater than the mean glandular dose. A technique to generate a two-compartment anthropomorphic breast phantom from bCT images has been demonstrated. The phantom is the first, to our knowledge, to accurately model the uncompressed pendant breast and the glandular tissue

Response of canine oesophagus to change in dose per fraction

International Nuclear Information System (INIS)

Gillette, E.L.; Hoopes, P.J.; Ensley, B.A.

1986-01-01

Data are presented from which it is concluded that the amount of glandular tissue in the submucosa at 6 months may be related to the residual increase in connective tissue component. If the connective tissue component continues to increase it could lead to further decreases in glandular tissues and thinning of the epithelium of the oesophagus. Significant atrophy of the submucosal oesophageal glands could have serious clinical implications. (author)

Scattering influence in mammographic image

International Nuclear Information System (INIS)

Poletti, Martin Eduardo; Almeida, Adelaide de

1996-01-01

The quantification of mammographic images affected by scattered radiation is studied. The average glandular dose as a function of kVp and breast thickness for breast composition 50/50% is also evaluated. The results show that the contrast decreases with increasing of kVp and breast thickness, and the average glandular dose increase with increasing breast thickness and decreases with increasing kVp

A model for automation of radioactive dose control

International Nuclear Information System (INIS)

Ribeiro, Carlos Henrique Calazans; Zambon, Jose Waldir; Bitelli, Ricardo; Honaiser, Eduardo Henrique Rangel

2009-01-01

The paper presents a proposal for automation of the personnel dose control system to be used in nuclear medicine environments. The model has considered the Standards and rules of the National Commission of Nuclear Energy (CNEN) and of the Health Ministry. The advantages of the model is a robust management of the integrated dose and technicians qualification status. The software platform selected to be used was the Lotus Notes and an analysis of the advantages, disadvantages of the use of this platform is also presented. (author)

A model for automation of radioactive dose control

Energy Technology Data Exchange (ETDEWEB)

Ribeiro, Carlos Henrique Calazans; Zambon, Jose Waldir; Bitelli, Ricardo; Honaiser, Eduardo Henrique Rangel [Centro Tecnologico da Marinha em Sao Paulo (CTMSP), Sao Paulo, SP (Brazil)], e-mail: calazans@ctmsp.mar.mil.br, e-mail: zambon@ctmsp.mar.mil.br, e-mail: bitelli@ctmsp.mar.mil.br, e-mail: honaiser@ctmsp.mar.mil.br

2009-07-01

The paper presents a proposal for automation of the personnel dose control system to be used in nuclear medicine environments. The model has considered the Standards and rules of the National Commission of Nuclear Energy (CNEN) and of the Health Ministry. The advantages of the model is a robust management of the integrated dose and technicians qualification status. The software platform selected to be used was the Lotus Notes and an analysis of the advantages, disadvantages of the use of this platform is also presented. (author)

Recent developments in biokinetic models and the calculation of internal dose coefficients

International Nuclear Information System (INIS)

Fell, T.P.; Phipps, A.W.; Kendall, G.M.; Stradling, G.N.

1997-01-01

In most cases the measurement of radioactivity in an environmental or biological sample will be followed by some estimation of dose and possibly risk, either to a population or an individual. This will normally involve the use of a dose coefficient (dose per unit intake value) taken from a compendium. In recent years the calculation of dose coefficients has seen many developments in both biokinetic modelling and computational capabilities. ICRP has recommended new models for the respiratory tract and for the systemic behavior of many of the more important elements. As well as this, a general age-dependent calculation method has been developed which involves an effectively continuous variation of both biokinetic and dosimetric parameters, facilitating more realistic estimation of doses to young people. These new developments were used in work for recent ICRP, IAEA and CEC compendia of dose coefficients for both members of the public (including children) and workers. This paper presents a general overview of the method of calculation of internal doses with particular reference to the actinides. Some of the implications for dose coefficients of the new models are discussed. For example it is shown that compared with data in ICRP Publications 30 and 54: the new respiratory tract model generally predicts lower deposition in systemic tissues per unit intake; the new biokinetic models for actinides allow for burial of material deposited on bone surfaces; age-dependent models generally feature faster turnover of material in young people. All of these factors can lead to substantially different estimates of dose and examples of the new dose coefficients are given to illustrate these differences. During the development of the new models for actinides, human bioassay data were used to validate the model. Thus, one would expect the new models to give reasonable predictions of bioassay quantities. Some examples of the bioassay applications, e.g., excretion data for the

Radiation dose from Chernobyl forests: assessment using the 'forestpath' model

International Nuclear Information System (INIS)

Schell, W.R.; Linkov, I.; Belinkaia, E.; Rimkevich, V.; Zmushko, Yu.; Lutsko, A.; Fifield, F.W.; Flowers, A.G.; Wells, G.

1996-01-01

Contaminated forests can contribute significantly to human radiation dose for a few decades after initial contamination. Exposure occurs through harvesting the trees, manufacture and use of forest products for construction materials and paper production, and the consumption of food harvested from forests. Certain groups of the population, such as wild animal hunters and harvesters of berries, herbs and mushrooms, can have particularly large intakes of radionuclides from natural food products. Forestry workers have been found to receive radiation doses several times higher than other groups in the same area. The generic radionuclide cycling model 'forestpath' is being applied to evaluate the human radiation dose and risks to population groups resulting from living and working near the contaminated forests. The model enables calculations to be made to predict the internal and external radiation doses at specific times following the accident. The model can be easily adjusted for dose calculations from other contamination scenarios (such as radionuclide deposition at a low and constant rate as well as complex deposition patterns). Experimental data collected in the forests of Southern Belarus are presented. These data, together with the results of epidemiological studies, are used for model calibration and validation

Model-Based Individualized Treatment of Chemotherapeutics: Bayesian Population Modeling and Dose Optimization.

Directory of Open Access Journals (Sweden)

Devaraj Jayachandran

Full Text Available 6-Mercaptopurine (6-MP is one of the key drugs in the treatment of many pediatric cancers, auto immune diseases and inflammatory bowel disease. 6-MP is a prodrug, converted to an active metabolite 6-thioguanine nucleotide (6-TGN through enzymatic reaction involving thiopurine methyltransferase (TPMT. Pharmacogenomic variation observed in the TPMT enzyme produces a significant variation in drug response among the patient population. Despite 6-MP's widespread use and observed variation in treatment response, efforts at quantitative optimization of dose regimens for individual patients are limited. In addition, research efforts devoted on pharmacogenomics to predict clinical responses are proving far from ideal. In this work, we present a Bayesian population modeling approach to develop a pharmacological model for 6-MP metabolism in humans. In the face of scarcity of data in clinical settings, a global sensitivity analysis based model reduction approach is used to minimize the parameter space. For accurate estimation of sensitive parameters, robust optimal experimental design based on D-optimality criteria was exploited. With the patient-specific model, a model predictive control algorithm is used to optimize the dose scheduling with the objective of maintaining the 6-TGN concentration within its therapeutic window. More importantly, for the first time, we show how the incorporation of information from different levels of biological chain-of response (i.e. gene expression-enzyme phenotype-drug phenotype plays a critical role in determining the uncertainty in predicting therapeutic target. The model and the control approach can be utilized in the clinical setting to individualize 6-MP dosing based on the patient's ability to metabolize the drug instead of the traditional standard-dose-for-all approach.

Model-Based Individualized Treatment of Chemotherapeutics: Bayesian Population Modeling and Dose Optimization

Science.gov (United States)

Jayachandran, Devaraj; Laínez-Aguirre, José; Rundell, Ann; Vik, Terry; Hannemann, Robert; Reklaitis, Gintaras; Ramkrishna, Doraiswami

2015-01-01

6-Mercaptopurine (6-MP) is one of the key drugs in the treatment of many pediatric cancers, auto immune diseases and inflammatory bowel disease. 6-MP is a prodrug, converted to an active metabolite 6-thioguanine nucleotide (6-TGN) through enzymatic reaction involving thiopurine methyltransferase (TPMT). Pharmacogenomic variation observed in the TPMT enzyme produces a significant variation in drug response among the patient population. Despite 6-MP’s widespread use and observed variation in treatment response, efforts at quantitative optimization of dose regimens for individual patients are limited. In addition, research efforts devoted on pharmacogenomics to predict clinical responses are proving far from ideal. In this work, we present a Bayesian population modeling approach to develop a pharmacological model for 6-MP metabolism in humans. In the face of scarcity of data in clinical settings, a global sensitivity analysis based model reduction approach is used to minimize the parameter space. For accurate estimation of sensitive parameters, robust optimal experimental design based on D-optimality criteria was exploited. With the patient-specific model, a model predictive control algorithm is used to optimize the dose scheduling with the objective of maintaining the 6-TGN concentration within its therapeutic window. More importantly, for the first time, we show how the incorporation of information from different levels of biological chain-of response (i.e. gene expression-enzyme phenotype-drug phenotype) plays a critical role in determining the uncertainty in predicting therapeutic target. The model and the control approach can be utilized in the clinical setting to individualize 6-MP dosing based on the patient’s ability to metabolize the drug instead of the traditional standard-dose-for-all approach. PMID:26226448

Guidelines for Use of the Approximate Beta-Poisson Dose-Response Model.

Science.gov (United States)

Xie, Gang; Roiko, Anne; Stratton, Helen; Lemckert, Charles; Dunn, Peter K; Mengersen, Kerrie

2017-07-01

For dose-response analysis in quantitative microbial risk assessment (QMRA), the exact beta-Poisson model is a two-parameter mechanistic dose-response model with parameters α>0 and β>0, which involves the Kummer confluent hypergeometric function. Evaluation of a hypergeometric function is a computational challenge. Denoting PI(d) as the probability of infection at a given mean dose d, the widely used dose-response model PI(d)=1-(1+dβ)-α is an approximate formula for the exact beta-Poisson model. Notwithstanding the required conditions α1, issues related to the validity and approximation accuracy of this approximate formula have remained largely ignored in practice, partly because these conditions are too general to provide clear guidance. Consequently, this study proposes a probability measure Pr(0 (22α̂)0.50 for 0.020.99) . This validity measure and rule of thumb were validated by application to all the completed beta-Poisson models (related to 85 data sets) from the QMRA community portal (QMRA Wiki). The results showed that the higher the probability Pr(0 Poisson model dose-response curve. © 2016 Society for Risk Analysis.

Health effects of low doses at low dose rates: dose-response relationship modeling in a cohort of workers of the nuclear industry

International Nuclear Information System (INIS)

Metz-Flamant, Camille

2011-01-01

The aim of this thesis is to contribute to a better understanding of the health effects of chronic external low doses of ionising radiation. This work is based on the French cohort of CEA-AREVA NC nuclear workers. The mains stages of this thesis were (1) conducting a review of epidemiological studies on nuclear workers, (2) completing the database and performing a descriptive analysis of the cohort, (3) quantifying risk by different statistical methods and (4) modelling the exposure-time-risk relationship. The cohort includes monitored workers employed more than one year between 1950 and 1994 at CEA or AREVA NC companies. Individual annual external exposure, history of work, vital status and causes of death were reconstructed for each worker. Standardized mortality ratios using French national mortality rates as external reference were computed. Exposure-risk analysis was conducted in the cohort using the linear excess relative risk model, based on both Poisson regression and Cox model. Time dependent modifying factors were investigated by adding an interaction term in the model or by using exposure time windows. The cohort includes 36, 769 workers, followed-up until age 60 in average. During the 1968- 2004 period, 5, 443 deaths, 2, 213 cancers, 62 leukemia and 1, 314 cardiovascular diseases were recorded. Among the 57% exposed workers, the mean cumulative dose was 21.5 milli-sieverts (mSv). A strong Healthy Worker Effect is observed in the cohort. Significant elevated risks of pleura cancer and melanoma deaths were observed in the cohort but not associated with dose. No significant association was observed with solid cancers, lung cancer and cardiovascular diseases. A significant dose-response relationship was observed for leukemia excluding chronic lymphatic leukemia, mainly for doses received less than 15 years before and for yearly dose rates higher than 10 mSv. This PhD work contributes to the evaluation of risks associated to chronic external radiation

SU-E-T-43: Analytical Model for Photon Peripheral Dose in Radiotherapy Treatments

Energy Technology Data Exchange (ETDEWEB)

Nieto, B Sanchez; El far, R [Instituto de Fisica, Pontificia Universidad Catolica de Chile, Santiago, Santiago De Chile (Chile); Romero-Exposito, M [Universitat Autonoma de Barcelona, Barcelona (Spain); Lagares, J [Centro de Investigaciones Energeticas Medioambientales y Tecnologicas, Madrid (Spain); Mateo, JC [Hospital Duques del Infantado, Sevilla (Spain); Terron, JA [Servicio de Radiofisica, Hospital Universitario Virgen Macarena, Sevilla (Spain); Irazola, L; Sanchez-Doblado, F [Servicio de Radiofisica, Hospital Universitario Virgen Macarena, Sevilla (Spain); Departamento de Fisiologia Medica y Biofisica, Universidad de Sevilla, Sevilla (Spain)

2014-06-01

Purpose: The higher survival rate of radiotherapy patients entails a growing concern on second cancers associated to peripheral doses. Currently, dosimetry of out-of field doses is still under development. Our group has developed a methodology to estimate neutron equivalent dose in organs (1,2). We aimed to propose a model to estimate out-of-field photon doses in isocentric treatments from basic clinical data. Methods: The proposed function models the dose as the sum of leakage and scatter terms. The latter is modeled as a virtual source at the collimator, which suffers from attenuation in air and tissue, corrected by the inverse-square-law. The model was parameterized using experimental measurements with TLD700 chips placed inside an anthropomorphic phantom (6–18MV) irradiated with conformal and modulated techniques in Elekta, Siemens and Varian linacs. This model provides photon dose at a point as a function of clinical parameters as prescription dose/UM, PTV volume, distance to the field edge, height of the MLC leaves and distance from the the MLC to the isocenter. Model was tested against independent measurements (TLD100) for a VMAT treatment on a Elekta. Dose to organs is modeled from dose to points along the head-to-feet axis of the organ of a “standard man” escalated by patient height. Results: Our semi-empirical model depends on 3 given parameters (leakage parameter can be individualized). A novelty of our model, over other models (e.g., PERIDOSE), arises from its applicability to any technique (independently of the number of MU needed to deliver a dose). Differences between predictions and measurements were < 0.005mSv/UM. Conclusion: We have proposed a unique model which successfully account for photon peripheral organ dose. This model can be applied in the day-to-day clinic as it only needs a few basic parameters which are readily accessible.1. Radiother. Oncol. 107:234–243, 2013. 2. Phys. Med. Biol. 57:6167–6191, 2012.

SU-E-T-43: Analytical Model for Photon Peripheral Dose in Radiotherapy Treatments

International Nuclear Information System (INIS)

Nieto, B Sanchez; El far, R; Romero-Exposito, M; Lagares, J; Mateo, JC; Terron, JA; Irazola, L; Sanchez-Doblado, F

2014-01-01

Purpose: The higher survival rate of radiotherapy patients entails a growing concern on second cancers associated to peripheral doses. Currently, dosimetry of out-of field doses is still under development. Our group has developed a methodology to estimate neutron equivalent dose in organs (1,2). We aimed to propose a model to estimate out-of-field photon doses in isocentric treatments from basic clinical data. Methods: The proposed function models the dose as the sum of leakage and scatter terms. The latter is modeled as a virtual source at the collimator, which suffers from attenuation in air and tissue, corrected by the inverse-square-law. The model was parameterized using experimental measurements with TLD700 chips placed inside an anthropomorphic phantom (6–18MV) irradiated with conformal and modulated techniques in Elekta, Siemens and Varian linacs. This model provides photon dose at a point as a function of clinical parameters as prescription dose/UM, PTV volume, distance to the field edge, height of the MLC leaves and distance from the the MLC to the isocenter. Model was tested against independent measurements (TLD100) for a VMAT treatment on a Elekta. Dose to organs is modeled from dose to points along the head-to-feet axis of the organ of a “standard man” escalated by patient height. Results: Our semi-empirical model depends on 3 given parameters (leakage parameter can be individualized). A novelty of our model, over other models (e.g., PERIDOSE), arises from its applicability to any technique (independently of the number of MU needed to deliver a dose). Differences between predictions and measurements were < 0.005mSv/UM. Conclusion: We have proposed a unique model which successfully account for photon peripheral organ dose. This model can be applied in the day-to-day clinic as it only needs a few basic parameters which are readily accessible.1. Radiother. Oncol. 107:234–243, 2013. 2. Phys. Med. Biol. 57:6167–6191, 2012

Technical feasibility proof for high-resolution low-dose photon-counting CT of the breast

Energy Technology Data Exchange (ETDEWEB)

Kalender, Willi A.; Kolditz, Daniel; Lueck, Ferdinand [University of Erlangen-Nuernberg, Institute of Medical Physics (IMP), Erlangen (Germany); CT Imaging GmbH, Erlangen (Germany); Steiding, Christian [University of Erlangen-Nuernberg, Institute of Medical Physics (IMP), Erlangen (Germany); CT Imaging GmbH, Erlangen (Germany); University Hospital of Erlangen, Institute of Radiology, Erlangen (Germany); Ruth, Veikko; Roessler, Ann-Christin [University of Erlangen-Nuernberg, Institute of Medical Physics (IMP), Erlangen (Germany); Wenkel, Evelyn [University Hospital of Erlangen, Institute of Radiology, Erlangen (Germany)

2017-03-15

X-ray computed tomography (CT) has been proposed and evaluated multiple times as a potentially alternative method for breast imaging. All efforts shown so far have been criticized and partly disapproved because of their limited spatial resolution and higher patient dose when compared to mammography. Our concept for a dedicated breast CT (BCT) scanner therefore aimed at novel apparatus and detector design to provide high spatial resolution of about 100 μm and average glandular dose (AGD) levels of 5 mGy or below. Photon-counting technology was considered as a solution to reach these goals. The complete concept was previously evaluated and confirmed by simulations and basic experiments on laboratory setups. We here present measurements of dose, technical image quality parameters and surgical specimen results on such a scanner. For comparison purposes, the specimens were also imaged with digital mammography (DM) and breast tomosynthesis (BT) apparatus. Results show that photon-counting BCT (pcBCT) at 5 mGy AGD offers sufficiently high 3D spatial resolution for reliable detectability of calcifications and soft tissue delineation. (orig.)

Fractional poisson--a simple dose-response model for human norovirus.

Science.gov (United States)

Messner, Michael J; Berger, Philip; Nappier, Sharon P

2014-10-01

This study utilizes old and new Norovirus (NoV) human challenge data to model the dose-response relationship for human NoV infection. The combined data set is used to update estimates from a previously published beta-Poisson dose-response model that includes parameters for virus aggregation and for a beta-distribution that describes variable susceptibility among hosts. The quality of the beta-Poisson model is examined and a simpler model is proposed. The new model (fractional Poisson) characterizes hosts as either perfectly susceptible or perfectly immune, requiring a single parameter (the fraction of perfectly susceptible hosts) in place of the two-parameter beta-distribution. A second parameter is included to account for virus aggregation in the same fashion as it is added to the beta-Poisson model. Infection probability is simply the product of the probability of nonzero exposure (at least one virus or aggregate is ingested) and the fraction of susceptible hosts. The model is computationally simple and appears to be well suited to the data from the NoV human challenge studies. The model's deviance is similar to that of the beta-Poisson, but with one parameter, rather than two. As a result, the Akaike information criterion favors the fractional Poisson over the beta-Poisson model. At low, environmentally relevant exposure levels (Poisson model; however, caution is advised because no subjects were challenged at such a low dose. New low-dose data would be of great value to further clarify the NoV dose-response relationship and to support improved risk assessment for environmentally relevant exposures. © 2014 Society for Risk Analysis Published 2014. This article is a U.S. Government work and is in the public domain for the U.S.A.

Use of nonlinear dose-effect models to predict consequences

International Nuclear Information System (INIS)

Seiler, F.A.; Alvarez, J.L.

1996-01-01

The linear dose-effect relationship was introduced as a model for the induction of cancer from exposure to nuclear radiation. Subsequently, it has been used by analogy to assess the risk of chemical carcinogens also. Recently, however, the model for radiation carcinogenesis has come increasingly under attack because its calculations contradict the epidemiological data, such as cancer in atomic bomb survivors. Even so, its proponents vigorously defend it, often using arguments that are not so much scientific as a mix of scientific, societal, and often political arguments. At least in part, the resilience of the linear model is due to two convenient properties that are exclusive to linearity: First, the risk of an event is determined solely by the event dose; second, the total risk of a population group depends only on the total population dose. In reality, the linear model has been conclusively falsified; i.e., it has been shown to make wrong predictions, and once this fact is generally realized, the scientific method calls for a new paradigm model. As all alternative models are by necessity nonlinear, all the convenient properties of the linear model are invalid, and calculational procedures have to be used that are appropriate for nonlinear models

A model for dose estimation in therapy of liver with intraarterial microspheres

International Nuclear Information System (INIS)

Zavgorodni, S.F.

1996-01-01

Therapy with intraarterial microspheres is a technique which involves incorporation of radioisotope-labelled microspheres into a capillary bed of tumour and normal tissue. Beta-emitters such as 90 Y and 166 Ho are used for this purpose. This technique provides tumour to normal tissue (TNT) dose ratios in the range of 2-10 and demonstrates significant clinical benefit, which could potentially be increased with more accurate dose predictions and delivery. However, dose calculations in this modality face the difficulties associated with nonuniform and inhomogeneous activity distribution. Most of the dose calculations used clinically do not account for the nonuniformity and assume uniform activity distribution. This paper is devoted to the development of a model which would allow more accurate prediction of dose distributions from microspheres. The model calculates dose assuming that microspheres are aggregated into randomly distributed clusters, and using precomputed dose kernels for the clusters. The dose kernel due to a microsphere cluster was found by numerical integration of a point source dose kernel over the volume of the cluster. It is shown that a random distribution of clusters produces an intercluster distance distribution which agrees well with the one measured by Pillai et al in liver. Dose volume histograms (DVHs) predicted by the model agree closely with the results of Roberson et al for normal tissue and tumour. Dose distributions for different concentrations and types of radioisotope, as well as for tumours of different radii, have been calculated to demonstrate the model's possible applications. (author)

Radiation burden of patients due to mammography

International Nuclear Information System (INIS)

Novak, L.; Rada, J.

2005-01-01

A mammographic dose survey performed in the Czech Republic is based on evaluation of MGD for cranio-caudal (CC) and medio-lateral oblique (MLO) view, which are the standard mammographic projections. The study started in the year 2005, aims of the study are to establish new diagnostic reference levels (DRL) with regards to compressed breast thickness (current DRL is 3 mGy for a 45 mm PMMA breast phantom with 50% glandularity and Mo/Mo combination of filter and anode material) and to analyze an influence of different X -ray machine types, image receptors and imaging techniques on doses to patients. The calculation of mean glandular dose is based on a formalism suggested by Dance and accepted by European Commission. Mean glandular dose is computed from incident air kerma (without backscatter) using tabulated conversion coefficients for different breast thickness, beam quality and patient age. (authors)

The role of dose inhomogeneity in biological models of dose response

International Nuclear Information System (INIS)

Crawford-Brown, D.J.

1989-01-01

The paper focuses on the semi-empirical functions proposed by NAS (1980), ICRP (1977), in which terms for initiation and cell killing appear. The extent is not to produce a new model of carcinogenesis, or to reanalyse existing epidemiological data, but to explore whether an existing extrapolation function (proposed by the NAS) can be shown to have coherent theoretical support, while at the same time reproducing (however reasonably) the features of epidemiological data. Attention is restricted to irradiation by high LET radiations such as alpha particles, which may produce large inhomogeneities in both emission density and dose in cellular populations. Particular interest is directed towards epidemiological studies of uranium miners (Hornung and Meinhardt, 1987) and persons injected with 224 Ra (Spiess and Mays, 1970), although the results of the radium dial studies are included since they are discussed in the NAS report. Both populations are characterized by large uncertainties in dose estimation (mean organ dose) and by highly inhomogeneous patterns of irradiation within a single organ (Arnold and Jee, 1959; Diel, 1978; Singh, Bennettee and Wrenn, 1987; Rowland and Marshall, 1959). (author)

Dose-rate dependent stochastic effects in radiation cell-survival models

International Nuclear Information System (INIS)

Sachs, R.K.; Hlatky, L.R.

1990-01-01

When cells are subjected to ionizing radiation the specific energy rate (microscopic analog of dose-rate) varies from cell to cell. Within one cell, this rate fluctuates during the course of time; a crossing of a sensitive cellular site by a high energy charged particle produces many ionizations almost simultaneously, but during the interval between events no ionizations occur. In any cell-survival model one can incorporate the effect of such fluctuations without changing the basic biological assumptions. Using stochastic differential equations and Monte Carlo methods to take into account stochastic effects we calculated the dose-survival rfelationships in a number of current cell survival models. Some of the models assume quadratic misrepair; others assume saturable repair enzyme systems. It was found that a significant effect of random fluctuations is to decrease the theoretically predicted amount of dose-rate sparing. In the limit of low dose-rates neglecting the stochastic nature of specific energy rates often leads to qualitatively misleading results by overestimating the surviving fraction drastically. In the opposite limit of acute irradiation, analyzing the fluctuations in rates merely amounts to analyzing fluctuations in total specific energy via the usual microdosimetric specific energy distribution function, and neglecting fluctuations usually underestimates the surviving fraction. The Monte Carlo methods interpolate systematically between the low dose-rate and high dose-rate limits. As in other approaches, the slope of the survival curve at low dose-rates is virtually independent of dose and equals the initial slope of the survival curve for acute radiation. (orig.)

Personalized estimates of radiation dose from dedicated breast CT in a diagnostic population and comparison with diagnostic mammography

International Nuclear Information System (INIS)

Vedantham, Srinivasan; Shi, Linxi; Karellas, Andrew; O'Connell, Avice M; Conover, David L

2013-01-01

This study retrospectively analyzed the mean glandular dose (MGD) to 133 breasts from 132 subjects, all women, who participated in a clinical trial evaluating dedicated breast CT in a diagnostic population. The clinical trial was conducted in adherence to a protocol approved by institutional review boards and the study participants provided written informed consent. Individual estimates of MGD to each breast from dedicated breast CT was obtained by combining x-ray beam characteristics with estimates of breast dimensions and fibroglandular fraction from volumetric breast CT images, and using normalized glandular dose coefficients. For each study participant and for the breast corresponding to that imaged with breast CT, an estimate of the MGD from diagnostic mammography (including supplemental views) was obtained from the DICOM image headers for comparison. This estimate uses normalized glandular dose coefficients corresponding to a breast with 50% fibroglandular weight fraction. The median fibroglandular weight fraction for the study cohort determined from volumetric breast CT images was 15%. Hence, the MGD from diagnostic mammography was corrected to be representative of the study cohort. Individualized estimates of MGD from breast CT ranged from 5.7 to 27.8 mGy. Corresponding to the breasts imaged with breast CT, the MGD from diagnostic mammography ranged from 2.6 to 31.6 mGy. The mean (± inter-breast SD) and the median MGD (mGy) from dedicated breast CT exam were 13.9 ± 4.6 and 12.6, respectively. For the corresponding breasts, the mean (± inter-breast SD) and the median MGD (mGy) from diagnostic mammography were 12.4 ± 6.3 and 11.1, respectively. Statistical analysis indicated that at the 0.05 level, the distributions of MGD from dedicated breast CT and diagnostic mammography were significantly different (Wilcoxon signed ranks test, p = 0.007). While the interquartile range and the range (maximum–minimum) of MGD from dedicated breast CT was lower than

Forward-scattered radiation from the compression paddle should be considered in glandular dose estimations

International Nuclear Information System (INIS)

Hemdal, B.

2011-01-01

From major protocols on dosimetry in mammography, there is no doubt that the incident air kerma should be evaluated without backscattered radiation to the dosemeter. However, forward-scattered radiation from the compression paddle is neglected. The aim of this work was to analyse the contribution of forward-scattered radiation for typical air kerma measurements. Measurements of forward-scatter were performed with a plane-parallel ionisation chamber on four mammography units. The forward-scatter contribution to the air kerma was 2-10 % and increased with the compression paddle thickness, but also with the half-value layer value. For incident air kerma in mammography, it can be as important to consider forward scattered as backscattered radiation. If an ionisation chamber is used, the compression paddle should be in contact with the chamber; otherwise the air kerma and absorbed dose will be underestimated. If a dosemeter based on semiconductors with much less sensitivity to scattered radiation is used, it is suggested that a forward-scatter factor (FSF) is applied. Based on the results of this work, FSF=1.06 will lead to a maximum error of ∼4 %. (authors)

TSD-DOSE: A radiological dose assessment model for treatment, storage, and disposal facilities

International Nuclear Information System (INIS)

Pfingston, M.; Arnish, J.; LePoire, D.; Chen, S.-Y.

1998-01-01

Past practices at US Department of Energy (DOE) field facilities resulted in the presence of trace amounts of radioactive materials in some hazardous chemical wastes shipped from these facilities. In May 1991, the DOE Office of Waste Operations issued a nationwide moratorium on shipping all hazardous waste until procedures could be established to ensure that only nonradioactive hazardous waste would be shipped from DOE facilities to commercial treatment, storage, and disposal (TSD) facilities. To aid in assessing the potential impacts of shipments of mixed radioactive and chemically hazardous wastes, a radiological assessment computer model (or code) was developed on the basis of detailed assessments of potential radiological exposures and doses for eight commercial hazardous waste TSD facilities. The model, called TSD-DOSE, is designed to incorporate waste-specific and site-specific data to estimate potential radiological doses to on-site workers and the off-site public from waste-handling operations at a TSD facility. The code is intended to provide both DOE and commercial TSD facilities with a rapid and cost-effective method for assessing potential human radiation exposures from the processing of chemical wastes contaminated with trace amounts of radionuclides

Comprehensive fluence model for absolute portal dose image prediction

International Nuclear Information System (INIS)

Chytyk, K.; McCurdy, B. M. C.

2009-01-01

Amorphous silicon (a-Si) electronic portal imaging devices (EPIDs) continue to be investigated as treatment verification tools, with a particular focus on intensity modulated radiation therapy (IMRT). This verification could be accomplished through a comparison of measured portal images to predicted portal dose images. A general fluence determination tailored to portal dose image prediction would be a great asset in order to model the complex modulation of IMRT. A proposed physics-based parameter fluence model was commissioned by matching predicted EPID images to corresponding measured EPID images of multileaf collimator (MLC) defined fields. The two-source fluence model was composed of a focal Gaussian and an extrafocal Gaussian-like source. Specific aspects of the MLC and secondary collimators were also modeled (e.g., jaw and MLC transmission factors, MLC rounded leaf tips, tongue and groove effect, interleaf leakage, and leaf offsets). Several unique aspects of the model were developed based on the results of detailed Monte Carlo simulations of the linear accelerator including (1) use of a non-Gaussian extrafocal fluence source function, (2) separate energy spectra used for focal and extrafocal fluence, and (3) different off-axis energy spectra softening used for focal and extrafocal fluences. The predicted energy fluence was then convolved with Monte Carlo generated, EPID-specific dose kernels to convert incident fluence to dose delivered to the EPID. Measured EPID data were obtained with an a-Si EPID for various MLC-defined fields (from 1x1 to 20x20 cm 2 ) over a range of source-to-detector distances. These measured profiles were used to determine the fluence model parameters in a process analogous to the commissioning of a treatment planning system. The resulting model was tested on 20 clinical IMRT plans, including ten prostate and ten oropharyngeal cases. The model predicted the open-field profiles within 2%, 2 mm, while a mean of 96.6% of pixels over all

Absorbed dose modeled for a liquid circulating around a Co-60 irradiator

International Nuclear Information System (INIS)

Mangussi, J.

2013-01-01

A model for the distribution of the absorbed dose in a volume of liquid circulating into an active tank containing a Co-60 irradiator is presented. The absorbed dose, the stir process and the liquid recirculation into the active tank are modeled. The absorbed dose for different fractions of the volume is calculated. The necessary irradiation times for the achievement of the required absorbed dose are evaluated. (author)

A demonstration of dose modeling at Yucca Mountain

International Nuclear Information System (INIS)

Miley, T.B.; Eslinger, P.W.

1992-11-01

The U. S. Environmental Protection Agency is currently revising the regulatory guidance for high-level nuclear waste disposal. In its draft form, the guidelines contain dose limits. Since this is likely to be the case in the final regulations, it is essential that the US Department of Energy be prepared to calculate site-specific doses for any potential repository location. This year, Pacific Northwest Laboratory (PNL) has made a first attempt to estimate doses for the potential geologic repository at Yucca Mountain, Nevada as part of a preliminary total-systems performance assessment. A set of transport scenarios was defined to assess the cumulative release of radionuclides over 10,000 years under undisturbed and disturbed conditions at Yucca Mountain. Dose estimates were provided for several of the transport scenarios modeled. The exposure scenarios used to estimate dose in this total-systems exercise should not, however, be considered a definitive set of scenarios for determining the risk of the potential repository. Exposure scenarios were defined for waterborne and surface contamination that result from both undisturbed and disturbed performance of the potential repository. The exposure scenarios used for this analysis were designed for the Hanford Site in Washington. The undisturbed performance scenarios for which exposures were modeled are gas-phase release of 14 C to the surface and natural breakdown of the waste containers with waterborne release. The disturbed performance scenario for which doses were estimated is exploratory drilling. Both surface and waterborne contamination were considered for the drilling intrusion scenario

Identification, functional characterization and developmental regulation of sesquiterpene synthases from sunflower capitate glandular trichomes

Directory of Open Access Journals (Sweden)

Ro Dae-Kyun

2009-07-01

Full Text Available Abstract Background Sesquiterpene lactones are characteristic metabolites of Asteraceae (or Compositae which often display potent bioactivities and are sequestered in specialized organs such as laticifers, resin ducts, and trichomes. For characterization of sunflower sesquiterpene synthases we employed a simple method to isolate pure trichomes from anther appendages which facilitated the identification of these genes and investigation of their enzymatic functions and expression patterns during trichome development. Results Glandular trichomes of sunflower (Helianthus annuus L. were isolated, and their RNA was extracted to investigate the initial steps of sesquiterpene lactone biosynthesis. Reverse transcription-PCR experiments led to the identification of three sesquiterpene synthases. By combination of in vitro and in vivo characterization of sesquiterpene synthase gene products in Escherichia coli and Saccharomyces cerevisiae, respectively, two enzymes were identified as germacrene A synthases, the key enzymes of sesquiterpene lactone biosynthesis. Due to the very low in vitro activity, the third enzyme was expressed in vivo in yeast as a thioredoxin-fusion protein for functional characterization. In in vivo assays, it was identified as a multiproduct enzyme with the volatile sesquiterpene hydrocarbon δ-cadinene as one of the two main products with α-muuorlene, β-caryophyllene, α-humulene and α-copaene as minor products. The second main compound remained unidentified. For expression studies, glandular trichomes from the anther appendages of sunflower florets were isolated in particular developmental stages from the pre- to the post-secretory phase. All three sesquiterpene synthases were solely upregulated during the biosynthetically active stages of the trichomes. Expression in different aerial plant parts coincided with occurrence and maturity of trichomes. Young roots with root hairs showed expression of the sesquiterpene synthase genes

A unified framework for benchmark dose estimation applied to mixed models and model averaging

DEFF Research Database (Denmark)

Ritz, Christian; Gerhard, Daniel; Hothorn, Ludwig A.

2013-01-01

for hierarchical data structures, reflecting increasingly common types of assay data. We illustrate the usefulness of the methodology by means of a cytotoxicology example where the sensitivity of two types of assays are evaluated and compared. By means of a simulation study, we show that the proposed framework......This article develops a framework for benchmark dose estimation that allows intrinsically nonlinear dose-response models to be used for continuous data in much the same way as is already possible for quantal data. This means that the same dose-response model equations may be applied to both...

Current modeling practice may lead to falsely high benchmark dose estimates.

Science.gov (United States)

Ringblom, Joakim; Johanson, Gunnar; Öberg, Mattias

2014-07-01

Benchmark dose (BMD) modeling is increasingly used as the preferred approach to define the point-of-departure for health risk assessment of chemicals. As data are inherently variable, there is always a risk to select a model that defines a lower confidence bound of the BMD (BMDL) that, contrary to expected, exceeds the true BMD. The aim of this study was to investigate how often and under what circumstances such anomalies occur under current modeling practice. Continuous data were generated from a realistic dose-effect curve by Monte Carlo simulations using four dose groups and a set of five different dose placement scenarios, group sizes between 5 and 50 animals and coefficients of variations of 5-15%. The BMD calculations were conducted using nested exponential models, as most BMD software use nested approaches. "Non-protective" BMDLs (higher than true BMD) were frequently observed, in some scenarios reaching 80%. The phenomenon was mainly related to the selection of the non-sigmoidal exponential model (Effect=a·e(b)(·dose)). In conclusion, non-sigmoid models should be used with caution as it may underestimate the risk, illustrating that awareness of the model selection process and sound identification of the point-of-departure is vital for health risk assessment. Copyright © 2014 The Authors. Published by Elsevier Inc. All rights reserved.

Comparison of two dose and three dose human papillomavirus vaccine schedules: cost effectiveness analysis based on transmission model.

Science.gov (United States)

Jit, Mark; Brisson, Marc; Laprise, Jean-François; Choi, Yoon Hong

2015-01-06

To investigate the incremental cost effectiveness of two dose human papillomavirus vaccination and of additionally giving a third dose. Cost effectiveness study based on a transmission dynamic model of human papillomavirus vaccination. Two dose schedules for bivalent or quadrivalent human papillomavirus vaccines were assumed to provide 10, 20, or 30 years' vaccine type protection and cross protection or lifelong vaccine type protection without cross protection. Three dose schedules were assumed to give lifelong vaccine type and cross protection. United Kingdom. Males and females aged 12-74 years. No, two, or three doses of human papillomavirus vaccine given routinely to 12 year old girls, with an initial catch-up campaign to 18 years. Costs (from the healthcare provider's perspective), health related utilities, and incremental cost effectiveness ratios. Giving at least two doses of vaccine seems to be highly cost effective across the entire range of scenarios considered at the quadrivalent vaccine list price of £86.50 (€109.23; $136.00) per dose. If two doses give only 10 years' protection but adding a third dose extends this to lifetime protection, then the third dose also seems to be cost effective at £86.50 per dose (median incremental cost effectiveness ratio £17,000, interquartile range £11,700-£25,800). If two doses protect for more than 20 years, then the third dose will have to be priced substantially lower (median threshold price £31, interquartile range £28-£35) to be cost effective. Results are similar for a bivalent vaccine priced at £80.50 per dose and when the same scenarios are explored by parameterising a Canadian model (HPV-ADVISE) with economic data from the United Kingdom. Two dose human papillomavirus vaccine schedules are likely to be the most cost effective option provided protection lasts for at least 20 years. As the precise duration of two dose schedules may not be known for decades, cohorts given two doses should be closely

Dose rate effect models for biological reaction to ionizing radiation in human cell lines

International Nuclear Information System (INIS)

Magae, Junji; Ogata, Hiromitsu

2008-01-01

Full text: Because of biological responses to ionizing radiation are dependent on irradiation time or dose rate as well as dose, simultaneous inclusion of dose and dose rate is required to evaluate the risk of long term irradiation at low dose rates. We previously published a novel statistical model for dose rate effect, modified exponential (MOE) model, which predicts irradiation time-dependent biological response to low dose rate ionizing radiation, by analyzing micronucleus formation and growth inhibition in a human osteosarcoma cell line, exposed to wide range of doses and dose rates of gamma-rays. MOE model demonstrates that logarithm of median effective dose exponentially increases in low dose rates, and thus suggests that the risk approaches to zero at infinitely low dose rate. In this paper, we extend the analysis in various kinds of human cell lines exposed to ionizing radiation for more than a year. We measured micronucleus formation and [ 3 H]thymidine uptake in human cell lines including an osteosarcoma, a DNA-dependent protein kinase-deficient glioma, a SV40-transformed fibroblast derived from an ataxia telangiectasia patient, a normal fibroblast, and leukemia cell lines. Cells were exposed to gamma-rays in irradiation room bearing 50,000 Ci of cobalt-60. After the irradiation, they were cultured for 24 h in the presence of cytochalasin B to block cytokinesis, and cytoplasm and nucleus were stained with DAPI and prospidium iodide. The number of binuclear cells bearing a micronucleus was counted under a fluorescence microscope. For proliferation inhibition, cells were cultured for 48 h after the irradiation and [ 3 H] thymidine was pulsed for 4 h before harvesting. We statistically analyzed the data for quantitative evaluation of radiation risk. While dose and dose rate relationship cultured within one month followed MOE model in cell lines holding wild-type DNA repair system, dose rate effect was greatly impaired in DNA repair-deficient cell lines

Addressing model uncertainty in dose-response: The case of chloroform

International Nuclear Information System (INIS)

Evans, J.S.

1994-01-01

This paper discusses the issues involved in addressing model uncertainty in the analysis of dose-response relationships. A method for addressing model uncertainty is described and applied to characterize the uncertainty in estimates of the carcinogenic potency of chloroform. The approach, which is rooted in Bayesian concepts of subjective probability, uses probability trees and formally-elicited expert judgments to address model uncertainty. It is argued that a similar approach could be used to improve the characterization of model uncertainty in the dose-response relationships for health effects from ionizing radiation

The MESORAD dose assessment model: Computer code

International Nuclear Information System (INIS)

Ramsdell, J.V.; Athey, G.F.; Bander, T.J.; Scherpelz, R.I.

1988-10-01

MESORAD is a dose equivalent model for emergency response applications that is designed to be run on minicomputers. It has been developed by the Pacific Northwest Laboratory for use as part of the Intermediate Dose Assessment System in the US Nuclear Regulatory Commission Operations Center in Washington, DC, and the Emergency Management System in the US Department of Energy Unified Dose Assessment Center in Richland, Washington. This volume describes the MESORAD computer code and contains a listing of the code. The technical basis for MESORAD is described in the first volume of this report (Scherpelz et al. 1986). A third volume of the documentation planned. That volume will contain utility programs and input and output files that can be used to check the implementation of MESORAD. 18 figs., 4 tabs

A model to accumulate fractionated dose in a deforming organ

International Nuclear Information System (INIS)

Yan Di; Jaffray, D.A.; Wong, J.W.

1999-01-01

Purpose: Measurements of internal organ motion have demonstrated that daily organ deformation exists throughout the course of radiation treatment. However, a method of constructing the resultant dose delivered to the organ volume remains a difficult challenge. In this study, a model to quantify internal organ motion and a method to construct a cumulative dose in a deforming organ are introduced. Methods and Materials: A biomechanical model of an elastic body is used to quantify patient organ motion in the process of radiation therapy. Intertreatment displacements of volume elements in an organ of interest is calculated by applying an finite element method with boundary conditions, obtained from multiple daily computed tomography (CT) measurements. Therefore, by incorporating also the measurements of daily setup error, daily dose delivered to a deforming organ can be accumulated by tracking the position of volume elements in the organ. Furthermore, distribution of patient-specific organ motion is also predicted during the early phase of treatment delivery using the daily measurements, and the cumulative dose distribution in the organ can then be estimated. This dose distribution will be updated whenever a new measurement becomes available, and used to reoptimize the ongoing treatment. Results: An integrated process to accumulate dosage in a daily deforming organ was implemented. In this process, intertreatment organ motion and setup error were systematically quantified, and incorporated in the calculation of the cumulative dose. An example of the rectal wall motion in a prostate treatment was applied to test the model. The displacements of volume elements in the rectal wall, as well as the resultant doses, were calculated. Conclusion: This study is intended to provide a systematic framework to incorporate daily patient-specific organ motion and setup error in the reconstruction of the cumulative dose distribution in an organ of interest. The realistic dose

Optimization of technique factors for a silicon diode array full-field digital mammography system and comparison to screen-film mammography with matched average glandular dose

International Nuclear Information System (INIS)

Berns, Eric A.; Hendrick, R. Edward; Cutter, Gary R.

2003-01-01

Contrast-detail experiments were performed to optimize technique factors for the detection of low-contrast lesions using a silicon diode array full-field digital mammography (FFDM) system under the conditions of a matched average glandular dose (AGD) for different techniques. Optimization was performed for compressed breast thickness from 2 to 8 cm. FFDM results were compared to screen-film mammography (SFM) at each breast thickness. Four contrast-detail (CD) images were acquired on a SFM unit with optimal techniques at 2, 4, 6, and 8 cm breast thicknesses. The AGD for each breast thickness was calculated based on half-value layer (HVL) and entrance exposure measurements on the SFM unit. A computer algorithm was developed and used to determine FFDM beam current (mAs) that matched AGD between FFDM and SFM at each thickness, while varying target, filter, and peak kilovoltage (kVp) across the full range available for the FFDM unit. CD images were then acquired on FFDM for kVp values from 23-35 for a molybdenum-molybdenum (Mo-Mo), 23-40 for a molybdenum-rhodium (Mo-Rh), and 25-49 for a rhodium-rhodium (Rh-Rh) target-filter under the constraint of matching the AGD from screen-film for each breast thickness (2, 4, 6, and 8 cm). CD images were scored independently for SFM and each FFDM technique by six readers. CD scores were analyzed to assess trends as a function of target-filter and kVp and were compared to SFM at each breast thickness. For 2 cm thick breasts, optimal FFDM CD scores occurred at the lowest possible kVp setting for each target-filter, with significant decreases in FFDM CD scores as kVp was increased under the constraint of matched AGD. For 2 cm breasts, optimal FFDM CD scores were not significantly different from SFM CD scores. For 4-8 cm breasts, optimum FFDM CD scores were superior to SFM CD scores. For 4 cm breasts, FFDM CD scores decreased as kVp increased for each target-filter combination. For 6 cm breasts, CD scores decreased slightly as k

Proof of concept and dose estimation with binary responses under model uncertainty.

Science.gov (United States)

Klingenberg, B

2009-01-30

This article suggests a unified framework for testing Proof of Concept (PoC) and estimating a target dose for the benefit of a more comprehensive, robust and powerful analysis in phase II or similar clinical trials. From a pre-specified set of candidate models, we choose the ones that best describe the observed dose-response. To decide which models, if any, significantly pick up a dose effect, we construct the permutation distribution of the minimum P-value over the candidate set. This allows us to find critical values and multiplicity adjusted P-values that control the familywise error rate of declaring any spurious effect in the candidate set as significant. Model averaging is then used to estimate a target dose. Popular single or multiple contrast tests for PoC, such as the Cochran-Armitage, Dunnett or Williams tests, are only optimal for specific dose-response shapes and do not provide target dose estimates with confidence limits. A thorough evaluation and comparison of our approach to these tests reveal that its power is as good or better in detecting a dose-response under various shapes with many more additional benefits: It incorporates model uncertainty in PoC decisions and target dose estimation, yields confidence intervals for target dose estimates and extends to more complicated data structures. We illustrate our method with the analysis of a Phase II clinical trial. Copyright (c) 2008 John Wiley & Sons, Ltd.

Radiation dose modeling using IGRIP and Deneb/ERGO

International Nuclear Information System (INIS)

Vickers, D.S.; Davis, K.R.; Breazeal, N.L.; Watson, R.A.; Ford, M.S.

1995-01-01

The Radiological Environment Modeling System (REMS) quantifies dose to humans in radiation environments using the IGRIP (Interactive Graphical Robot Instruction Program) and Deneb/ERGO (Ergonomics) simulation software products. These commercially available products are augmented with custom C code to provide the radiation exposure information to and collect the radiation dose information from the workcell simulations. The emphasis of this paper is on the IGRIP and Deneb/ERGO parts of REMS, since that represents the extension to existing capabilities developed by the authors. Through the use of any radiation transport code or measured data, a radiation exposure input database may be formulated. User-specified IGRIP simulations utilize these database files to compute and accumulate dose to human devices (Deneb's ERGO human) during simulated operations around radiation sources. Timing, distances, shielding, and human activity may be modeled accurately in the simulations. The accumulated dose is recorded in output files, and the user is able to process and view this output. REMS was developed because the proposed reduction in the yearly radiation exposure limit will preclude or require changes in many of the manual operations currently being utilized in the Weapons Complex. This is particularly relevant in the area of dismantlement activities at the Pantex Plant in Amarillo, TX. Therefore, a capability was needed to be able to quantify the dose associated with certain manual processes so that the benefits of automation could be identified and understood

Introduction of computed radiography in two mammography services: image quality and dose analysis

International Nuclear Information System (INIS)

Jakubiak, Rosangela R.; Gamba, Humberto R.; Ramos, Maria M.; Faversani, Gislene G.; Peixoto, Joao E.

2008-01-01

This study has evaluated the impact of the introduction of CR technology in the routine of two mammography services operating with Lorad Affinity X-ray units and CR Fuji Profect One system. Mean glandular dose was determined to set Automatic Exposure Control parameters according to optimal image quality. Reject analysis of patient images was made to establish the overall impact in routine work. As regards to dose evaluation, the results show that in 44% of mammography exams the MGD were above action levels. It is due to inadequate AEC adjustment and insufficient training of the staff in operating CR systems. In addition, common errors with screen/film systems like wrong breast positing and selection of exposure parameters, as well as X-ray unit failures like insufficient anti scatter grid movement still occurs. This is an indication that ongoing efforts should be concentrated in the constancy of AEC adjustment for CR image plates and staff training. Until now, brazilian health authorities did not implement any program to evaluate digital systems performance, but efforts are being done in order to provide guidelines to breast screening aiming the control of breast dose compatible with optimal image quality. (author)

Assessment of body doses from photon exposures using human voxel models

International Nuclear Information System (INIS)

Zankl, M.; Fill, U.; Petoussi-Henss, N.; Regulla, D.

2000-01-01

For the scope of risk assessment in protection against ionising radiation (occupational, environmental and medical) it is necessary to determine the radiation dose to specific body organs and tissues. For this purpose, a series of models of the human body were designed in the past, together with computer codes simulating the radiation transport and energy deposition in the body. Most of the computational body models in use are so-called mathematical models; the most famous is the MIRD-5 phantom developed at Oak Ridge National Laboratory. In the 1980s, a new generation of human body models was introduced at GSF, constructed from whole body CT data. Due to being constructed from image data of real persons, these 'voxel models' offer an improved realism of external and internal shape of the body and its organs, compared to MIRD-type models. Comparison of dose calculations involving voxel models with respective dose calculations for MIRD-type models revealed that the deviation of the individual anatomy from that described in the MIRD-type models indeed introduces significant deviations of the calculated organ doses. Specific absorbed fractions of energy released in a source organ due to incorporated activity which are absorbed in target organs may differ by more than an order of magnitude between different body models; for external photon irradiation, the discrepancies are more moderate. (author)

Speculation on improving personal dosimetry in mammography

International Nuclear Information System (INIS)

Nicoll, J.J.

1996-01-01

The increasing importance of radiation protection of the patient in diagnostic radiology has created an interest in the dose individuals receive from X-ray mammography, although this is an area where the most important aspect of protection is based on the inter comparison of machines using phantoms and standard conditions. In 1987 the ICRP established the critical quantity as being the average absorbed dose to the glandular tissue of the breast, and identified a composition of 50% adipose; 50% glandular tissue as a reference. Several authors have published experimental and monte carlo simulation resuluts to enable the determination of this quantity from output, beam quality and compressed breast thickness. Many centres, including ourselves, have studied the distribution of radiation dose on this basis. The result is however dependant on the assumption made about tissue composition. It is apparently common knowledge among pathologists and frequently mentioned in general anatomy texts, that the amount of glandular tissue is independent of breast size; that is larger breasts will have a higher adipose:glandular tissue ratio. Such a systematic variation would lead to an overestimate of the dose being received by women with larger breasts. I will review the availabe pathology and demonstrate the effect of applying the assumed breast composition on our own data. (author)

Increased adrenocortical response to adrenocorticotropic hormone (ACTH) in sport horses with equine glandular gastric disease (EGGD).

Science.gov (United States)

Scheidegger, M D; Gerber, V; Bruckmaier, R M; van der Kolk, J H; Burger, D; Ramseyer, A

2017-10-01

This study tested the hypothesis that adrenocortical function would be altered in horses with equine gastric ulcer syndrome (EGUS). Twenty-six sport horses competing at national or international levels in eventing (n=15) or endurance (n=11) were subjected to a gastroscopic examination and an adrenocorticotropic hormone (ACTH) stimulation test. Salivary cortisol concentrations were measured before (baseline) and after (30, 60, 90, 120 and 150min) IV ACTH injection (1μg/kg bodyweight). Within EGUS, two distinct diseases, equine squamous gastric disease (ESGD) and equine glandular gastric disease (EGGD), can be distinguished. ESGD was diagnosed in 8/11 (73%; 95% confidence intervals [95%CI], 43-92%) endurance horses and 5/15 (33%; 95% CI, 14-58%) eventing horses. EGGD was observed in 9/11 (82%; 95% CI, 53-96%) endurance horses and 9/15 (60%; 95% CI, 35-81%) eventing horses. The presence or severity of ESGD was unrelated to the presence or severity of EGGD. ACTH stimulation induced a larger increase in cortisol concentration in horses with moderate EGGD than in horses with mild EGGD. Cortisol concentration during the entire sampling period (total increase in cortisol concentration during the entire sampling period [dAUC], 31.1±6.4ng/mL) and the highest measured concentration at a single time point (maximal increase in cortisol concentration [dMAX], 10.3±2.3ng/mL) were increased (P=0.005 and P=0.038, respectively), indicating that horses with glandular gastric disease exhibited increased adrenocortical responses to ACTH stimulation. These results suggest that EGGD might be associated with an enhanced adrenocortical sensitivity. Further investigations are warranted to confirm the association between adrenocortical sensitivity and EGGD and to elucidate the pathophysiological mechanisms involved. Copyright © 2017 Elsevier Ltd. All rights reserved.

Evaluation of the dose assessment models for routine radioactive releases to the environment

International Nuclear Information System (INIS)

Rossi, J.

1998-05-01

The aim of the work was to evaluate the needs of development concerning the dose calculation models for routine releases and application of the models for exceptional release situations at the NPP plants operated by Imatran Voima Ltd. and Teollisuuden Voima Ltd. in Finland. First, the differences of the calculation models concerning input data, models themselves and output are considered. Subsequently some single features like importance of nuclides in exposure pathways due to change of the release composition, dose calculation for children and importance of time period of particle releases are considered. The existing dose calculation model used by the radiation safety authorities is aimed at a tool for checking the results from calculations of doses arising from routine releases by the power companies. Characteristics of an independent, foreign model and its suitability for safety authorities for dose calculations of releases in normal operation is also assessed. The needs of improvements in the existing calculation models and characteristics of a comprehensive model for safety authorities are discussed as well

Modeling low-dose-rate effects in irradiated bipolar-base oxides

International Nuclear Information System (INIS)

Graves, R.J.; Cirba, C.R.; Schrimpf, R.D.; Milanowski, R.J.; Saigne, F.; Michez, A.; Fleetwood, D.M.; Witczak, S.C.

1997-02-01

A physical model is developed to quantify the contribution of oxide-trapped charge to enhanced low-dose-rate gain degradation in BJTs. Simulations show that space charge limited transport is partially responsible for the low-dose-rate enhancement

Activity measurement and effective dose modelling of natural radionuclides in building material

International Nuclear Information System (INIS)

Maringer, F.J.; Baumgartner, A.; Rechberger, F.; Seidel, C.; Stietka, M.

2013-01-01

In this paper the assessment of natural radionuclides' activity concentration in building materials, calibration requirements and related indoor exposure dose models is presented. Particular attention is turned to specific improvements in low-level gamma-ray spectrometry to determine the activity concentration of necessary natural radionuclides in building materials with adequate measurement uncertainties. Different approaches for the modelling of the effective dose indoor due to external radiation resulted from natural radionuclides in building material and results of actual building material assessments are shown. - Highlights: • Dose models for indoor radiation exposure due to natural radionuclides in building materials. • Strategies and methods in radionuclide metrology, activity measurement and dose modelling. • Selection of appropriate parameters in radiation protection standards for building materials. • Scientific-based limitations of indoor exposure due to natural radionuclides in building materials

Calculating external doses from contaminated soil with the computer model SOILD

International Nuclear Information System (INIS)

Chen, Y.; LePoire, D.; Yu, C.

1991-01-01

The SOILD computer model was developed for calculating the effective dose equivalent from external exposure to distributed gamma sources in soil. It is designed to assess external doses under various exposure scenarios that may be encountered in environmental restoration programs. The model's four major functional features address (a) dose versus source depth in soil, (b) shielding of clean cover soil, (c) area of contamination, and (d) nonuniform distribution of sources. The model can also adjust doses when there are variations in soil densities for both source and cover soils. It is supported by a data base of ∼500 radionuclides. A sample calculation was performed by SOILD to determine the effective dose equivalent for a uniform source distribution in soil. The soil density was assumed to be 1.6 g/cm 3 , and the source strength was assumed to be 1 pCi/cm 3 . The following radionuclides were studied: 60 C, 131 I, 137+D Cs, 238+D U, and 226+D Ra ('+D' denotes the parent nuclide and daughters)

A unique case of a huge mixed squamous cell and glandular papilloma of non-endobronchial origin with a peripheral growth

Directory of Open Access Journals (Sweden)

Kei Yabuki

Full Text Available We report a case of a huge solitary non-endobronchial pulmonary tumor in a 76-year-old male smoker. The tumor measured 11 × 10 × 8 cm. It was ill-defined, and it was located periphery of the right lower lobe with the subpleural cystic spaces. He underwent right lower lobectomy with mediastinal lymph node dissection and is free from tumor 30 months after surgery. Microscopically, it was composed of a proliferation of squamous and ciliated columnar epithelial cells with a few mucous cells. These cells were arranged in a papillary growth fashion extending along the fibrously thickened alveolar septa together with metaplastic bronchiolar and squamous epithelia displaying an usual interstitial pneumonia-pattern. Although the histologic features of the tumor were that of a mixed squamous cell and glandular papilloma (MSCGP, it was peripherally located and showed a lepidic growth, and it was much larger than previously reported MSCGPs. It is possible that the tumor developed in association with bronchial metaplasia in the periphery of the lung, and then extended along the surface of the reconstructed air spaces, which resulted in its unique histologic appearance. Further investigations of respiratory papilloma are needed to clarify the pathogenesis of these lesions. Keywords: Mixed squamous cell and glandular papilloma, Non-endobronchial, Cytology, Interstitial pneumonia, Pulmonary tumor

Evaluation of Mird and Marinelli formalisms in the radiation dosimetry for thyroid of adults and children using 131I (radioiodine)

International Nuclear Information System (INIS)

Vasquez, A.M.; Rocha, J.J.; Castillo, D.C.; Gomez, M.A.; Mendoza, A.A.; Rabanal, M.J.; Cruz, S.J.

2013-01-01

Using MIRD formalism and Cristy-Eckerman representation for the thyroid adults, children of 15, 10, 5, 1 year old and newborn it is shown that the total dose absorbed by the gland due to 131 I(iodine) is its self-dose. Their results are not significantly different from those reported by the formalism MARINELLI (self-dose), which uses a sphere as glandular representation. Consequently, the kinetic model to the gland is a single compartment and the thyroid can be represented as a sphere

An audit of cervicovaginal cytology in a teaching hospital: Are atypical glandular cells under-recognised on cytological screening?

Science.gov (United States)

Crasta, Julian A; Chaitra, V; Simi, Cm; Correa, Marjorie

2009-04-01

Cervical cytology screening for carcinoma of the cervix in India is mainly opportunistic in nature and is practiced mainly in urban centres. The effectiveness of cervical cytology screening depends on various factors. The quality of cervicovaginal cytology service is assessed by various quality indices and by cyto-histology correlation, which is the most important quality assurance measure. To describe the cervical cytology diagnoses, estimate the quality indices, and evaluate the discrepant cases on cytohistological correlation. Retrospective observational study from a tertiary care centre in South India. Using a database search, all the cervicovaginal cytology reported during the period of 2002-2006 was retrieved and various diagnoses were described. The data was analysed to assess the quality indices. The cytohistologically discrepant cases were reviewed. A total of 10,787 cases were retrieved, of which 98.14% were labeled negative and 1.36% were unsatisfactory for evaluation. A few (0.81%) of the cases were labeled as squamous intraepithelial lesions and 0.38% as atypical squamous cells. The ASCUS: SIL ratio was 0.5. Cytohistological correlation revealed a total of ten cases with significant discrepancy. The majority of these were carcinomas that were misdiagnosed as atypical glandular cells. These cytology smears and the subsequent biopsies were reviewed to elucidate the reasons for the discrepancies. The cervical cytology service at our centre is well within the accepted standards. An increased awareness of cytological features, especially of glandular lesions, a good clinician-laboratory communication and a regular cytohistological review would further improve the diagnostic standards.

Dose rate modelled for the outdoors of a gamma irradiation

International Nuclear Information System (INIS)

Mangussi, J

2012-01-01

A model for the absorbed dose rate calculation on the surroundings of a gamma irradiation plant is developed. In such plants, a part of the radiation emitted upwards reach's the outdoors. The Compton scatterings on the wall of the exhausting pipes through de plant roof and on the outdoors air are modelled. The absorbed dose rate generated by the scattered radiation as far as 200 m is calculated. The results of the models, to be used for the irradiation plant design and for the environmental studies, are showed on graphics (author)

Experimental characterization and physical modelling of the dose distribution of scanned proton pencil beams

International Nuclear Information System (INIS)

Pedroni, E; Scheib, S; Boehringer, T; Coray, A; Grossmann, M; Lin, S; Lomax, A

2005-01-01

In this paper we present the pencil beam dose model used for treatment planning at the PSI proton gantry, the only system presently applying proton therapy with a beam scanning technique. The scope of the paper is to give a general overview on the various components of the dose model, on the related measurements and on the practical parametrization of the results. The physical model estimates from first physical principles absolute dose normalized to the number of incident protons. The proton beam flux is measured in practice by plane-parallel ionization chambers (ICs) normalized to protons via Faraday-cup measurements. It is therefore possible to predict and deliver absolute dose directly from this model without other means. The dose predicted in this way agrees very well with the results obtained with ICs calibrated in a cobalt beam. Emphasis is given in this paper to the characterization of nuclear interaction effects, which play a significant role in the model and are the major source of uncertainty in the direct estimation of the absolute dose. Nuclear interactions attenuate the primary proton flux, they modify the shape of the depth-dose curve and produce a faint beam halo of secondary dose around the primary proton pencil beam in water. A very simple beam halo model has been developed and used at PSI to eliminate the systematic dependences of the dose observed as a function of the size of the target volume. We show typical results for the relative (using a CCD system) and absolute (using calibrated ICs) dosimetry, routinely applied for the verification of patient plans. With the dose model including the nuclear beam halo we can predict quite precisely the dose directly from treatment planning without renormalization measurements, independently of the dose, shape and size of the dose fields. This applies also to the complex non-homogeneous dose distributions required for the delivery of range-intensity-modulated proton therapy, a novel therapy technique

A review of a priori regression models for warfarin maintenance dose prediction.

Directory of Open Access Journals (Sweden)

Ben Francis

Full Text Available A number of a priori warfarin dosing algorithms, derived using linear regression methods, have been proposed. Although these dosing algorithms may have been validated using patients derived from the same centre, rarely have they been validated using a patient cohort recruited from another centre. In order to undertake external validation, two cohorts were utilised. One cohort formed by patients from a prospective trial and the second formed by patients in the control arm of the EU-PACT trial. Of these, 641 patients were identified as having attained stable dosing and formed the dataset used for validation. Predicted maintenance doses from six criterion fulfilling regression models were then compared to individual patient stable warfarin dose. Predictive ability was assessed with reference to several statistics including the R-square and mean absolute error. The six regression models explained different amounts of variability in the stable maintenance warfarin dose requirements of the patients in the two validation cohorts; adjusted R-squared values ranged from 24.2% to 68.6%. An overview of the summary statistics demonstrated that no one dosing algorithm could be considered optimal. The larger validation cohort from the prospective trial produced more consistent statistics across the six dosing algorithms. The study found that all the regression models performed worse in the validation cohort when compared to the derivation cohort. Further, there was little difference between regression models that contained pharmacogenetic coefficients and algorithms containing just non-pharmacogenetic coefficients. The inconsistency of results between the validation cohorts suggests that unaccounted population specific factors cause variability in dosing algorithm performance. Better methods for dosing that take into account inter- and intra-individual variability, at the initiation and maintenance phases of warfarin treatment, are needed.

A review of a priori regression models for warfarin maintenance dose prediction.

Science.gov (United States)

Francis, Ben; Lane, Steven; Pirmohamed, Munir; Jorgensen, Andrea

2014-01-01

A number of a priori warfarin dosing algorithms, derived using linear regression methods, have been proposed. Although these dosing algorithms may have been validated using patients derived from the same centre, rarely have they been validated using a patient cohort recruited from another centre. In order to undertake external validation, two cohorts were utilised. One cohort formed by patients from a prospective trial and the second formed by patients in the control arm of the EU-PACT trial. Of these, 641 patients were identified as having attained stable dosing and formed the dataset used for validation. Predicted maintenance doses from six criterion fulfilling regression models were then compared to individual patient stable warfarin dose. Predictive ability was assessed with reference to several statistics including the R-square and mean absolute error. The six regression models explained different amounts of variability in the stable maintenance warfarin dose requirements of the patients in the two validation cohorts; adjusted R-squared values ranged from 24.2% to 68.6%. An overview of the summary statistics demonstrated that no one dosing algorithm could be considered optimal. The larger validation cohort from the prospective trial produced more consistent statistics across the six dosing algorithms. The study found that all the regression models performed worse in the validation cohort when compared to the derivation cohort. Further, there was little difference between regression models that contained pharmacogenetic coefficients and algorithms containing just non-pharmacogenetic coefficients. The inconsistency of results between the validation cohorts suggests that unaccounted population specific factors cause variability in dosing algorithm performance. Better methods for dosing that take into account inter- and intra-individual variability, at the initiation and maintenance phases of warfarin treatment, are needed.

Absorbed dose measurements in mammography using Monte Carlo method and ZrO2+PTFE dosemeters

International Nuclear Information System (INIS)

Duran M, H. A.; Hernandez O, M.; Salas L, M. A.; Hernandez D, V. M.; Vega C, H. R.; Pinedo S, A.; Ventura M, J.; Chacon, F.; Rivera M, T.

2009-10-01

Mammography test is a central tool for breast cancer diagnostic. In addition, programs are conducted periodically to detect the asymptomatic women in certain age groups; these programs have shown a reduction on breast cancer mortality. Early detection of breast cancer is achieved through a mammography, which contrasts the glandular and adipose tissue with a probable calcification. The parameters used for mammography are based on the thickness and density of the breast, their values depend on the voltage, current, focal spot and anode-filter combination. To achieve an image clear and a minimum dose must be chosen appropriate irradiation conditions. Risk associated with mammography should not be ignored. This study was performed in the General Hospital No. 1 IMSS in Zacatecas. Was used a glucose phantom and measured air Kerma at the entrance of the breast that was calculated using Monte Carlo methods and ZrO 2 +PTFE thermoluminescent dosemeters, this calculation was completed with calculating the absorbed dose. (author)

CT radiation dose and image quality optimization using a porcine model.

Science.gov (United States)

Zarb, Francis; McEntee, Mark F; Rainford, Louise

2013-01-01

To evaluate potential radiation dose savings and resultant image quality effects with regard to optimization of commonly performed computed tomography (CT) studies derived from imaging a porcine (pig) model. Imaging protocols for 4 clinical CT suites were developed based on the lowest milliamperage and kilovoltage, the highest pitch that could be set from current imaging protocol parameters, or both. This occurred before significant changes in noise, contrast, and spatial resolution were measured objectively on images produced from a quality assurance CT phantom. The current and derived phantom protocols were then applied to scan a porcine model for head, abdomen, and chest CT studies. Further optimized protocols were developed based on the same methodology as in the phantom study. The optimization achieved with respect to radiation dose and image quality was evaluated following data collection of radiation dose recordings and image quality review. Relative visual grading analysis of image quality criteria adapted from the European guidelines on radiology quality criteria for CT were used for studies completed with both the phantom-based or porcine-derived imaging protocols. In 5 out of 16 experimental combinations, the current clinical protocol was maintained. In 2 instances, the phantom protocol reduced radiation dose by 19% to 38%. In the remaining 9 instances, the optimization based on the porcine model further reduced radiation dose by 17% to 38%. The porcine model closely reflects anatomical structures in humans, allowing the grading of anatomical criteria as part of image quality review without radiation risks to human subjects. This study demonstrates that using a porcine model to evaluate CT optimization resulted in more radiation dose reduction than when imaging protocols were tested solely on quality assurance phantoms.

Model-based dose calculations for COMS eye plaque brachytherapy using an anatomically realistic eye phantom.

Science.gov (United States)

Lesperance, Marielle; Inglis-Whalen, M; Thomson, R M

2014-02-01

To investigate the effects of the composition and geometry of ocular media and tissues surrounding the eye on dose distributions for COMS eye plaque brachytherapy with(125)I, (103)Pd, or (131)Cs seeds, and to investigate doses to ocular structures. An anatomically and compositionally realistic voxelized eye model with a medial tumor is developed based on a literature review. Mass energy absorption and attenuation coefficients for ocular media are calculated. Radiation transport and dose deposition are simulated using the EGSnrc Monte Carlo user-code BrachyDose for a fully loaded COMS eye plaque within a water phantom and our full eye model for the three radionuclides. A TG-43 simulation with the same seed configuration in a water phantom neglecting the plaque and interseed effects is also performed. The impact on dose distributions of varying tumor position, as well as tumor and surrounding tissue media is investigated. Each simulation and radionuclide is compared using isodose contours, dose volume histograms for the lens and tumor, maximum, minimum, and average doses to structures of interest, and doses to voxels of interest within the eye. Mass energy absorption and attenuation coefficients of the ocular media differ from those of water by as much as 12% within the 20-30 keV photon energy range. For all radionuclides studied, average doses to the tumor and lens regions in the full eye model differ from those for the plaque in water by 8%-10% and 13%-14%, respectively; the average doses to the tumor and lens regions differ between the full eye model and the TG-43 simulation by 2%-17% and 29%-34%, respectively. Replacing the surrounding tissues in the eye model with water increases the maximum and average doses to the lens by 2% and 3%, respectively. Substituting the tumor medium in the eye model for water, soft tissue, or an alternate melanoma composition affects tumor dose compared to the default eye model simulation by up to 16%. In the full eye model

Model-based dose calculations for COMS eye plaque brachytherapy using an anatomically realistic eye phantom

International Nuclear Information System (INIS)

Lesperance, Marielle; Inglis-Whalen, M.; Thomson, R. M.

2014-01-01

Purpose : To investigate the effects of the composition and geometry of ocular media and tissues surrounding the eye on dose distributions for COMS eye plaque brachytherapy with 125 I, 103 Pd, or 131 Cs seeds, and to investigate doses to ocular structures. Methods : An anatomically and compositionally realistic voxelized eye model with a medial tumor is developed based on a literature review. Mass energy absorption and attenuation coefficients for ocular media are calculated. Radiation transport and dose deposition are simulated using the EGSnrc Monte Carlo user-code BrachyDose for a fully loaded COMS eye plaque within a water phantom and our full eye model for the three radionuclides. A TG-43 simulation with the same seed configuration in a water phantom neglecting the plaque and interseed effects is also performed. The impact on dose distributions of varying tumor position, as well as tumor and surrounding tissue media is investigated. Each simulation and radionuclide is compared using isodose contours, dose volume histograms for the lens and tumor, maximum, minimum, and average doses to structures of interest, and doses to voxels of interest within the eye. Results : Mass energy absorption and attenuation coefficients of the ocular media differ from those of water by as much as 12% within the 20–30 keV photon energy range. For all radionuclides studied, average doses to the tumor and lens regions in the full eye model differ from those for the plaque in water by 8%–10% and 13%–14%, respectively; the average doses to the tumor and lens regions differ between the full eye model and the TG-43 simulation by 2%–17% and 29%–34%, respectively. Replacing the surrounding tissues in the eye model with water increases the maximum and average doses to the lens by 2% and 3%, respectively. Substituting the tumor medium in the eye model for water, soft tissue, or an alternate melanoma composition affects tumor dose compared to the default eye model simulation by up

A system for environmental protection. Reference dose models for fauna and flora

International Nuclear Information System (INIS)

Pentreath, R.J.; Woodhead, D.S.

2000-01-01

Ideas have already been published on how the current problems relating to environmental protection could be explicitly addressed. One of the basic cornerstones of the proposed system is that of the use of reference dose models for fauna and flora, in a manner analogous to those used for the human species. The concept is that, for a number of both aquatic and terrestrial fauna and flora types, 'reference' dose models, and dose per unit (internal and external) exposure tables, could be compiled. These would then be used to draw broad conclusions on the likely effects for such organisms in relation to three broad environment end points of concern: life shortening; impairment of reproductive capacity; and scorable, cytogenetic damage. The level of complexity of the dose models needs to be commensurate with the morphological complexity of the modelled organism, its size, and the data bases which are either available or could be reasonably obtained. The most basic models considered are either solid ellipsoids or spheres, with fixed dimensions. Secondary models contain internal, but relatively simple geometric features representative of those key organs or tissues for which more precise estimates of dose are required. Their level of complexity is also a function of different internal and external sources of radiation, and expected differences in radiosensitivities. Tertiary models -of greater complexity- are only considered to be of value for higher vertebrates. The potential derivation and use of all three sets of models is briefly discussed. (author)

Intravascular brachytherapy: a model for the calculation of the dose

International Nuclear Information System (INIS)

Pirchio, Rosana; Martin, Gabriela; Rivera, Elena; Cricco, Graciela; Cocca, Claudia; Gutierrez, Alicia; Nunez, Mariel; Bergoc, Rosa; Guzman, Luis; Belardi, Diego

2002-01-01

In this study we present the radiation dose distribution for a theoretical model with Montecarlo simulation, and based on an experimental model developed for the study of the prevention of restenosis post-angioplasty employing intravascular brachytherapy. In the experimental in vivo model, the atherosclerotic plaques were induced in femoral arteries of male New Zealand rabbits through surgical intervention and later administration of cholesterol enriched diet. For the intravascular irradiation we employed a 32P source contained within the balloon used for the angioplasty. The radiation dose distributions were calculated using the Monte Carlo code MCNP4B according to a segment of a simulated artery. We studied the radiation dose distribution in the axial and radial directions for different thickness of the atherosclerotic plaques. The results will be correlated with the biologic effects observed by means of histological analysis of the irradiated arteries (Au)

Analysis of the NAEG model of transuranic radionuclide transport and dose

International Nuclear Information System (INIS)

Kercher, J.R.; Anspaugh, L.R.

1984-01-01

We analyze the model for estimating the dose FR-om /sup 239/Pu developed for the Nevada Applied Ecology Group (NAEG) by using sensitivity analysis and uncertainty analysis. Sensitivity analysis results suggest that the air pathway is the critical pathway for the organs receiving the highest dose. Soil concentration and the factors controlling air concentration are the most important parameters. The only organ whose dose is sensitive to parameters in the ingestion pathway is the GI tract. The air pathway accounts for 100% of the dose to lung, upper respiratory tract, and thoracic lymph nodes; and 95% of its dose via ingestion. Leafy vegetable ingestion accounts for 70% of the dose FR-om the ingestion pathway regardless of organ, peeled vegetables 20%; accidental soil ingestion 5%; ingestion of beef liver 4%; beef muscle 1%. Only a handful of model parameters control the dose for any one organ. The number of important parameters is usually less than 10. Uncertainty analysis indicates that choosing a uniform distribution for the input parameters produces a lognormal distribution of the dose. The ratio of the square root of the variance to the mean is three times greater for the doses than it is for the individual parameters. As found by the sensitivity analysis, the uncertainty analysis suggests that only a few parameters control the dose for each organ. All organs have similar distributions and variance to mean ratios except for the lymph modes. 16 references, 9 figures, 13 tables

Analysis of the NAEG model of transuranic radionuclide transport and dose

International Nuclear Information System (INIS)

Kercher, J.R.; Anspaugh, L.R.

1984-11-01

We analyze the model for estimating the dose from 239 Pu developed for the Nevada Applied Ecology Group (NAEG) by using sensitivity analysis and uncertainty analysis. Sensitivity analysis results suggest that the air pathway is the critical pathway for the organs receiving the highest dose. Soil concentration and the factors controlling air concentration are the most important parameters. The only organ whose dose is sensitive to parameters in the ingestion pathway is the GI tract. The air pathway accounts for 100% of the dose to lung, upper respiratory tract, and thoracic lymph nodes; and 95% of its dose via ingestion. Leafy vegetable ingestion accounts for 70% of the dose from the ingestion pathway regardless of organ, peeled vegetables 20%; accidental soil ingestion 5%; ingestion of beef liver 4%; beef muscle 1%. Only a handful of model parameters control the dose for any one organ. The number of important parameters is usually less than 10. Uncertainty analysis indicates that choosing a uniform distribution for the input parameters produces a lognormal distribution of the dose. The ratio of the square root of the variance to the mean is three times greater for the doses than it is for the individual parameters. As found by the sensitivity analysis, the uncertainty analysis suggests that only a few parameters control the dose for each organ. All organs have similar distributions and variance to mean ratios except for the lymph modes. 16 references, 9 figures, 13 tables

MO-FG-CAMPUS-IeP1-02: Dose Reduction in Contrast-Enhanced Digital Mammography Using a Photon-Counting Detector

Energy Technology Data Exchange (ETDEWEB)

Lee, S; Kang, S; Eom, J [Konyang University, Daejeon (Korea, Republic of)

2016-06-15

Purpose: Photon-counting detectors (PCDs) allow multi-energy X-ray imaging without additional exposures and spectral overlap. This capability results in the improvement of accuracy of material decomposition for dual-energy X-ray imaging and the reduction of radiation dose. In this study, the PCD-based contrast-enhanced dual-energy mammography (CEDM) was compared with the conventional CDEM in terms of radiation dose, image quality and accuracy of material decomposition. Methods: A dual-energy model was designed by using Beer-Lambert’s law and rational inverse fitting function for decomposing materials from a polychromatic X-ray source. A cadmium zinc telluride (CZT)-based PCD, which has five energy thresholds, and iodine solutions included in a 3D half-cylindrical phantom, which composed of 50% glandular and 50% adipose tissues, were simulated by using a Monte Carlo simulation tool. The low- and high-energy images were obtained in accordance with the clinical exposure conditions for the conventional CDEM. Energy bins of 20–33 and 34–50 keV were defined from X-ray energy spectra simulated at 50 kVp with different dose levels for implementing the PCD-based CDEM. The dual-energy mammographic techniques were compared by means of absorbed dose, noise property and normalized root-mean-square error (NRMSE). Results: Comparing to the conventional CEDM, the iodine solutions were clearly decomposed for the PCD-based CEDM. Although the radiation dose for the PCD-based CDEM was lower than that for the conventional CEDM, the PCD-based CDEM improved the noise property and accuracy of decomposition images. Conclusion: This study demonstrates that the PCD-based CDEM allows the quantitative material decomposition, and reduces radiation dose in comparison with the conventional CDEM. Therefore, the PCD-based CDEM is able to provide useful information for detecting breast tumor and enhancing diagnostic accuracy in mammography.

Three-dimensional dose-response models of risk for radiation injury carcinogenesis

International Nuclear Information System (INIS)

Raabe, O.G.

1988-01-01

The use of computer graphics in conjunction with three-dimensional models of dose-response relationships for chronic exposure to ionizing radiation dramaticly clarifies the separate and interactive roles of competing risks. The three dimensions are average dose rate, exposure time, and risk. As an example, the functionally injurious and carcinogenic responses after systemic uptake of Ra-226 by beagles, mice and people with consequent alpha particle irradiation of the bone are represented by three-dimensional dose-rate/time/response surfaces that demonstrate the contributions with the passage of time of the competing deleterious responses. These relationships are further evaluated by mathematical stripping with three-dimensional illustrations that graphically show the resultant separate contribution of each effect. Radiation bone injury predominates at high dose rates and bone cancer at intermediate dose rates. Low dose rates result in spontaneous deaths from natural aging, yielding a type of practical threshold for bone cancer induction. Risk assessment is benefited by the insights that become apparent with these three-dimensional models. The improved conceptualization afforded by them contributes to planning and evaluating epidemiological analyses and experimental studies

Radiation doses in volume-of-interest breast computed tomography—A Monte Carlo simulation study

Energy Technology Data Exchange (ETDEWEB)

Lai, Chao-Jen, E-mail: cjlai3711@gmail.com; Zhong, Yuncheng; Yi, Ying; Wang, Tianpeng; Shaw, Chris C. [Department of Imaging Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030-4009 (United States)

2015-06-15

Purpose: Cone beam breast computed tomography (breast CT) with true three-dimensional, nearly isotropic spatial resolution has been developed and investigated over the past decade to overcome the problem of lesions overlapping with breast anatomical structures on two-dimensional mammographic images. However, the ability of breast CT to detect small objects, such as tissue structure edges and small calcifications, is limited. To resolve this problem, the authors proposed and developed a volume-of-interest (VOI) breast CT technique to image a small VOI using a higher radiation dose to improve that region’s visibility. In this study, the authors performed Monte Carlo simulations to estimate average breast dose and average glandular dose (AGD) for the VOI breast CT technique. Methods: Electron–Gamma-Shower system code-based Monte Carlo codes were used to simulate breast CT. The Monte Carlo codes estimated were validated using physical measurements of air kerma ratios and point doses in phantoms with an ion chamber and optically stimulated luminescence dosimeters. The validated full cone x-ray source was then collimated to simulate half cone beam x-rays to image digital pendant-geometry, hemi-ellipsoidal, homogeneous breast phantoms and to estimate breast doses with full field scans. 13-cm in diameter, 10-cm long hemi-ellipsoidal homogeneous phantoms were used to simulate median breasts. Breast compositions of 25% and 50% volumetric glandular fractions (VGFs) were used to investigate the influence on breast dose. The simulated half cone beam x-rays were then collimated to a narrow x-ray beam with an area of 2.5 × 2.5 cm{sup 2} field of view at the isocenter plane and to perform VOI field scans. The Monte Carlo results for the full field scans and the VOI field scans were then used to estimate the AGD for the VOI breast CT technique. Results: The ratios of air kerma ratios and dose measurement results from the Monte Carlo simulation to those from the physical

Evaluation of Mird and Marinelli formalisms in the radiation dosimetry for thyroid of adults and children using {sup 131I} (radioiodine); Evaluacion de las dosimetrias Mird y de Marinelli en el estimado de dosis de radiacion para tiroides de adultos y ninos cuando se usa {sup 131}I (yoduro)

Energy Technology Data Exchange (ETDEWEB)

Vasquez, A.M.; Rocha, J.J.; Castillo, D.C.; Gomez, M.A.; Mendoza, A.A.; Rabanal, M.J.; Cruz, S.J. [Universidad Nacional de Trujillo (UNT-UCV), Trujillo (Peru). Grupo de Fisica Medica

2013-11-01

Using MIRD formalism and Cristy-Eckerman representation for the thyroid adults, children of 15, 10, 5, 1 year old and newborn it is shown that the total dose absorbed by the gland due to {sup 131}I(iodine) is its self-dose. Their results are not significantly different from those reported by the formalism MARINELLI (self-dose), which uses a sphere as glandular representation. Consequently, the kinetic model to the gland is a single compartment and the thyroid can be represented as a sphere.

Effect of Gamma Radiation on Morphology and Histology of Sex Pheromone Gland of Callosobruchus maculatus (F.) Female

International Nuclear Information System (INIS)

El-Degwi, M.S.; Salem, H.M.; El-Maasarawy, S.A.S.; Ismail, I.I.

2008-01-01

The pheromone gland in normal adult female of C. maculatus consists of an internal lobe composed of glandular epithelia cells, connected dorsally with the abdominal tip. It has many tubule opening dorsally in large sets which have a groove. The size of pheromone gland of 4-day old females increased than 2-day old females. There is no difference between the gland size of 6-day old females and 4-day ones, but it decreased in females of 8-day old. In this age the gland divided into two separate parts. When females 4-day old irradiated with 100 Gy the glandular cells were separated and the nuclei were not clear. The fat bodies were less in numbers than in unirradiated ones and the glandular cell membrane is irregular. After increasing the radiation dose to 200 Gy, the glandular cells destroyed and become undistinguished. All the tubule were closed. The glandular cells in the irradiated 6-day old females with 100 Gy were compact. The nuclei and cytoplasm are very difficult to distinguished, the cytoplasm is deteriorated. As increasing the irradiation dose to 200 Gy, the glandular tissue completely damaged and appeared as narrow ribbon. Scanning electron micrographs of the abdominal tip of C.maculatus showed that the sex pheromone releasing area contains a mammiform, also it has a large number of large setae which has groove

Low-Dose Contrast-Enhanced Breast CT Using Spectral Shaping Filters: An Experimental Study.

Science.gov (United States)

Makeev, Andrey; Glick, Stephen J

2017-12-01

Iodinated contrast-enhanced X-ray imaging of the breast has been studied with various modalities, including full-field digital mammography (FFDM), digital breast tomosynthesis (DBT), and dedicated breast CT. Contrast imaging with breast CT has a number of advantages over FFDM and DBT, including the lack of breast compression, and generation of fully isotropic 3-D reconstructions. Nonetheless, for breast CT to be considered as a viable tool for routine clinical use, it would be desirable to reduce radiation dose. One approach for dose reduction in breast CT is spectral shaping using X-ray filters. In this paper, two high atomic number filter materials are studied, namely, gadolinium (Gd) and erbium (Er), and compared with Al and Cu filters currently used in breast CT systems. Task-based performance is assessed by imaging a cylindrical poly(methyl methacrylate) phantom with iodine inserts on a benchtop breast CT system that emulates clinical breast CT. To evaluate detectability, a channelized hoteling observer (CHO) is used with sums of Laguerre-Gauss channels. It was observed that spectral shaping using Er and Gd filters substantially increased the dose efficiency (defined as signal-to-noise ratio of the CHO divided by mean glandular dose) as compared with kilovolt peak and filter settings used in commercial and prototype breast CT systems. These experimental phantom study results are encouraging for reducing dose of breast CT, however, further evaluation involving patients is needed.

Modified Exponential (MOE) Models: statistical Models for Risk Estimation of Low dose Rate Radiation

International Nuclear Information System (INIS)

Ogata, H.; Furukawa, C.; Kawakami, Y.; Magae, J.

2004-01-01

Simultaneous inclusion of dose and dose-rate is required to evaluate the risk of long term irradiation at low dose-rates, since biological responses to radiation are complex processes that depend both on irradiation time and total dose. Consequently, it is necessary to consider a model including cumulative dose,dose-rate and irradiation time to estimate quantitative dose-response relationship on the biological response to radiation. In this study, we measured micronucleus formation and (3H) thymidine uptake in U2OS, human osteosarcoma cell line, as indicators of biological response to gamma radiation. Cells were exposed to gamma ray in irradiation room bearing 50,000 Ci 60Co. After irradiation, they were cultured for 24h in the presence of cytochalasin B to block cytokinesis, and cytoplasm and nucleus were stained with DAPI and propidium iodide. The number of binuclear cells bearing a micronucleus was counted under a florescence microscope. For proliferation inhibition, cells were cultured for 48 h after the irradiation and (3h) thymidine was pulsed for 4h before harvesting. We statistically analyzed the data for quantitative evaluation of radiation risk at low dose/dose-rate. (Author)

Differential microRNA Analysis of Glandular Trichomes and Young Leaves in Xanthium strumarium L. Reveals Their Putative Roles in Regulating Terpenoid Biosynthesis

OpenAIRE

Fan, Rongyan; Li, Yuanjun; Li, Changfu; Zhang, Yansheng

2015-01-01

The medicinal plant Xanthium strumarium L. (X. strumarium) is covered with glandular trichomes, which are the sites for synthesizing pharmacologically active terpenoids such as xanthatin. MicroRNAs (miRNAs) are a class of 21-24 nucleotide (nt) non-coding RNAs, most of which are identified as regulators of plant growth development. Identification of miRNAs involved in the biosynthesis of plant secondary metabolites remains limited. In this study, high-throughput Illumina sequencing, combined w...

Plasminogen-independent initiation of the pro-urokinase activation cascade in vivo. Activation of pro-urokinase by glandular kallikrein (mGK-6) in plasminogen-deficient mice

DEFF Research Database (Denmark)

List, K; Jensen, Ole Nørregaard; Bugge, T H

2000-01-01

)-antitrypsin. We suggest that mouse glandular kallikrein mGK-6 is an activator of pro-uPA in the mouse urinary tract in vivo. Since this kallikrein is expressed in a number of tissues and also occurs in plasma, it can also be considered a candidate for a physiological pro-uPA activator in other locations....

User Guide for GoldSim Model to Calculate PA/CA Doses and Limits

Energy Technology Data Exchange (ETDEWEB)

Smith, F. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

2016-10-31

A model to calculate doses for solid waste disposal at the Savannah River Site (SRS) and corresponding disposal limits has been developed using the GoldSim commercial software. The model implements the dose calculations documented in SRNL-STI-2015-00056, Rev. 0 “Dose Calculation Methodology and Data for Solid Waste Performance Assessment (PA) and Composite Analysis (CA) at the Savannah River Site”.

A model for radiological dose assessment in an urban environment

International Nuclear Information System (INIS)

Hwang, Won Tae; Kim, Eun Han; Jeong, Hyo Joon; Suh, Kyung Suk; Han, Moon Hee

2007-01-01

A model for radiological dose assessment in an urban environment, METRO-K has been developed. Characteristics of the model are as follows ; 1) mathematical structures are simple (i.e. simplified input parameters) and easy to understand due to get the results by analytical methods using experimental and empirical data, 2) complex urban environment can easily be made up using only 5 types of basic surfaces, 3) various remediation measures can be applied to different surfaces by evaluating the exposure doses contributing from each contamination surface. Exposure doses contributing from each contamination surface at a particular location of a receptor were evaluated using the data library of kerma values as a function of gamma energy and contamination surface. A kerma data library was prepared for 7 representative types of Korean urban building by extending those data given for 4 representative types of European urban buildings. Initial input data are daily radionuclide concentration in air and precipitation, and fraction of chemical type. Final outputs are absorbed dose rate in air contributing from the basic surfaces as a function of time following a radionuclide deposition, and exposure dose rate contributing from various surfaces constituting the urban environment at a particular location of a receptor. As the result of a contaminative scenario for an apartment built-up area, exposure dose rates show a distinct difference for surrounding environment as well as locations of a receptor

Mechanistic formulation of a lineal-quadratic-linear (LQL) model: Split-dose experiments and exponentially decaying sources

International Nuclear Information System (INIS)

Guerrero, Mariana; Carlone, Marco

2010-01-01

Purpose: In recent years, several models were proposed that modify the standard linear-quadratic (LQ) model to make the predicted survival curve linear at high doses. Most of these models are purely phenomenological and can only be applied in the particular case of acute doses per fraction. The authors consider a mechanistic formulation of a linear-quadratic-linear (LQL) model in the case of split-dose experiments and exponentially decaying sources. This model provides a comprehensive description of radiation response for arbitrary dose rate and fractionation with only one additional parameter. Methods: The authors use a compartmental formulation of the LQL model from the literature. They analytically solve the model's differential equations for the case of a split-dose experiment and for an exponentially decaying source. They compare the solutions of the survival fraction with the standard LQ equations and with the lethal-potentially lethal (LPL) model. Results: In the case of the split-dose experiment, the LQL model predicts a recovery ratio as a function of dose per fraction that deviates from the square law of the standard LQ. The survival fraction as a function of time between fractions follows a similar exponential law as the LQ but adds a multiplicative factor to the LQ parameter β. The LQL solution for the split-dose experiment is very close to the LPL prediction. For the decaying source, the differences between the LQL and the LQ solutions are negligible when the half-life of the source is much larger than the characteristic repair time, which is the clinically relevant case. Conclusions: The compartmental formulation of the LQL model can be used for arbitrary dose rates and provides a comprehensive description of dose response. When the survival fraction for acute doses is linear for high dose, a deviation of the square law formula of the recovery ratio for split doses is also predicted.

An audit of cervicovaginal cytology in a teaching hospital: Are atypical glandular cells under-recognised on cytological screening?

Directory of Open Access Journals (Sweden)

Crasta Julian

2009-01-01

Full Text Available Background: Cervical cytology screening for carcinoma of the cervix in India is mainly opportunistic in nature and is practiced mainly in urban centres. The effectiveness of cervical cytology screening depends on various factors. The quality of cervicovaginal cytology service is assessed by various quality indices and by cyto-histology correlation, which is the most important quality assurance measure. Aims: To describe the cervical cytology diagnoses, estimate the quality indices, and evaluate the discrepant cases on cytohistological correlation. Settings and Design: Retrospective observational study from a tertiary care centre in South India. Materials and Methods: Using a database search, all the cervicovaginal cytology reported during the period of 2002-2006 was retrieved and various diagnoses were described. The data was analysed to assess the quality indices. The cytohistologically discrepant cases were reviewed. Results: A total of 10,787 cases were retrieved, of which 98.14% were labeled negative and 1.36% were unsatisfactory for evaluation. A few (0.81% of the cases were labeled as squamous intraepithelial lesions and 0.38% as atypical squamous cells. The ASCUS: SIL ratio was 0.5. Cytohistological correlation revealed a total of ten cases with significant discrepancy. The majority of these were carcinomas that were misdiagnosed as atypical glandular cells. These cytology smears and the subsequent biopsies were reviewed to elucidate the reasons for the discrepancies. Conclusions: The cervical cytology service at our centre is well within the accepted standards. An increased awareness of cytological features, especially of glandular lesions, a good clinician-laboratory communication and a regular cytohistological review would further improve the diagnostic standards.

New model for assessing dose and dose rate sensitivity of Gamma ray radiation loss in polarization maintaining optical fibers

International Nuclear Information System (INIS)

Zhang Hongchen; Liu Hai; Qiao Wenqiang; Xue Huijie; He Shiyu

2012-01-01

Highlights: ► Building a new phenomenological theory model to investigate the relation about the irradiation induced loss with irradiation dose and dose rate. ► The Gamma ray irradiation induced loss of the “Capsule” type and “Panda” type polarization maintaining optical fibers at 1310 nm wavelength are investigated. ► The anti irradiation performance of the “Panda” type polarization maintaining optical fiber is better than that of the “Capsule” type polarization maintaining optical fiber, the reason is that the stress region doped by GeO 2 . - Abstract: The Gamma ray irradiation induced loss of the “Capsule” type and “Panda” type polarization maintaining optical fibers at 1310 nm wavelength are investigated. A phenomenological theory model is introduced and the influence of irradiation dose and dose rate on the irradiation induced loss is discussed. The phenomenological theoretical results are consistent with the experimental results of the irradiation induced loss for the two types of polarization maintaining optical fibers. The anti irradiation performance of the “Panda” type polarization maintaining optical fiber is better than that of the “Capsule” type polarization maintaining optical fiber, the reason is that the stress region dope with GeO 2 . Meanwhile, both of the polarization maintaining optical fiber irradiation induced loss increase with increasing the irradiation dose. In the case of same dose, the high dose rate Gamma ray irradiation induced optical fiber losses are higher than that of the low dose rate.

Biological profiling and dose-response modeling tools ...

Science.gov (United States)

Through its ToxCast project, the U.S. EPA has developed a battery of in vitro high throughput screening (HTS) assays designed to assess the potential toxicity of environmental chemicals. At present, over 1800 chemicals have been tested in up to 600 assays, yielding a large number of concentration-response data sets. Standard processing of these data sets involves finding a best fitting mathematical model and set of model parameters that specify this model. The model parameters include quantities such as the half-maximal activity concentration (or “AC50”) that have biological significance and can be used to inform the efficacy or potency of a given chemical with respect to a given assay. All of this data is processed and stored in an online-accessible database and website: http://actor.epa.gov/dashboard2. Results from these in vitro assays are used in a multitude of ways. New pathways and targets can be identified and incorporated into new or existing adverse outcome pathways (AOPs). Pharmacokinetic models such as those implemented EPA’s HTTK R package can be used to translate an in vitro concentration into an in vivo dose; i.e., one can predict the oral equivalent dose that might be expected to activate a specific biological pathway. Such predicted values can then be compared with estimated actual human exposures prioritize chemicals for further testing.Any quantitative examination should be accompanied by estimation of uncertainty. We are developing met

New model for mines and transportation tunnels external dose calculation using Monte Carlo simulation

International Nuclear Information System (INIS)

Allam, Kh. A.

2017-01-01

In this work, a new methodology is developed based on Monte Carlo simulation for tunnels and mines external dose calculation. Tunnels external dose evaluation model of a cylindrical shape of finite thickness with an entrance and with or without exit. A photon transportation model was applied for exposure dose calculations. A new software based on Monte Carlo solution was designed and programmed using Delphi programming language. The variation of external dose due to radioactive nuclei in a mine tunnel and the corresponding experimental data lies in the range 7.3 19.9%. The variation of specific external dose rate with position in, tunnel building material density and composition were studied. The given new model has more flexible for real external dose in any cylindrical tunnel structure calculations. (authors)

Evolution of dose calculation models for proton-therapy treatment planning

International Nuclear Information System (INIS)

Vidal, Marie

2011-01-01

This work was achieved in collaboration between the Institut Curie proton-therapy Center of Orsay (ICPO), the DOSIsoft company and the CREATIS laboratory, in order to develop a new dose calculation model for the new ICPO treatment room. A new accelerator and gantry room from the IBA company were installed during the up-grade project of the proton-therapy center, with the intention of enlarging the cancer localizations treated at ICPO. Developing a package of methods and new dose calculation algorithms to adapt them to the new specific characteristics of the delivered beams by the IBA system is the first goal of this PhD work. They all aim to be implemented in the DOSIsoft treatment planning software, Isogray. First, the double scattering technique is treated in taking into account major differences between the IBA system and the ICPO fixed beam lines passive system. Secondly, a model is explored for the scanned beams modality. The second objective of this work is improving the Ray-Tracing and Pencil-Beam dose calculation models already in use. For the double scattering and uniform scanning techniques, the patient personalized collimator at the end of the beam line causes indeed a patient dose distribution contamination. A reduction method of that phenomenon was set up for the passive beam system. An analytical model was developed which describes the contamination function with parameters validated through Monte-Carlo simulations on the GATE platform. It allows us to apply those methods to active scanned beams [fr

Analysis and modeling of electronic portal imaging exit dose measurements

International Nuclear Information System (INIS)

Pistorius, S.; Yeboah, C.

1995-01-01

In spite of the technical advances in treatment planning and delivery in recent years, it is still unclear whether the recommended accuracy in dose delivery is being achieved. Electronic portal imaging devices, now in routine use in many centres, have the potential for quantitative dosimetry. As part of a project which aims to develop an expert-system based On-line Dosimetric Verification (ODV) system we have investigated and modelled the dose deposited in the detector of a video based portal imaging system. Monte Carlo techniques were used to simulate gamma and x-ray beams in homogeneous slab phantom geometries. Exit doses and energy spectra were scored as a function of (i) slab thickness, (ii) field size and (iii) the air gap between the exit surface and the detector. The results confirm that in order to accurately calculate the dose in the high atomic number Gd 2 O 2 S detector for a range of air gaps, field sizes and slab thicknesses both the magnitude of the primary and scattered components and their effective energy need to be considered. An analytic, convolution based model which attempts to do this is proposed. The results of the simulation and the ability of the model to represent these data will be presented and discussed. This model is used to show that, after training, a back-propagation feed-forward cascade correlation neural network has the ability to identify and recognise the cause of, significant dosimetric errors

User Guide for GoldSim Model to Calculate PA/CA Doses and Limits

International Nuclear Information System (INIS)

Smith, F.

2016-01-01

A model to calculate doses for solid waste disposal at the Savannah River Site (SRS) and corresponding disposal limits has been developed using the GoldSim commercial software. The model implements the dose calculations documented in SRNL-STI-2015-00056, Rev. 0 ''Dose Calculation Methodology and Data for Solid Waste Performance Assessment (PA) and Composite Analysis (CA) at the Savannah River Site''.

Animal model of acid-reflux esophagitis: pathogenic roles of acid/pepsin, prostaglandins, and amino acids.

Science.gov (United States)

Takeuchi, Koji; Nagahama, Kenji

2014-01-01

Esophagitis was induced in rats within 3 h by ligating both the pylorus and transitional region between the forestomach and glandular portion under ether anesthesia. This esophageal injury was prevented by the administration of acid suppressants and antipepsin drug and aggravated by exogenous pepsin. Damage was also aggravated by pretreatment with indomethacin and the selective COX-1 but not COX-2 inhibitor, whereas PGE2 showed a biphasic effect depending on the dose; a protection at low doses, and an aggravation at high doses, with both being mediated by EP1 receptors. Various amino acids also affected this esophagitis in different ways; L-alanine and L-glutamine had a deleterious effect, while L-arginine and glycine were highly protective, both due to yet unidentified mechanisms. It is assumed that acid/pepsin plays a major pathogenic role in this model of esophagitis; PGs derived from COX-1 are involved in mucosal defense of the esophagus; and some amino acids are protective against esophagitis. These findings also suggest a novel therapeutic approach in the treatment of esophagitis, in addition to acid suppressant therapy. The model introduced may be useful to test the protective effects of drugs on esophagitis and investigate the mucosal defense mechanism in the esophagus.

Analytical dose modeling for preclinical proton irradiation of millimetric targets.

Science.gov (United States)

Vanstalle, Marie; Constanzo, Julie; Karakaya, Yusuf; Finck, Christian; Rousseau, Marc; Brasse, David

2018-01-01

Due to the considerable development of proton radiotherapy, several proton platforms have emerged to irradiate small animals in order to study the biological effectiveness of proton radiation. A dedicated analytical treatment planning tool was developed in this study to accurately calculate the delivered dose given the specific constraints imposed by the small dimensions of the irradiated areas. The treatment planning system (TPS) developed in this study is based on an analytical formulation of the Bragg peak and uses experimental range values of protons. The method was validated after comparison with experimental data from the literature and then compared to Monte Carlo simulations conducted using Geant4. Three examples of treatment planning, performed with phantoms made of water targets and bone-slab insert, were generated with the analytical formulation and Geant4. Each treatment planning was evaluated using dose-volume histograms and gamma index maps. We demonstrate the value of the analytical function for mouse irradiation, which requires a targeting accuracy of 0.1 mm. Using the appropriate database, the analytical modeling limits the errors caused by misestimating the stopping power. For example, 99% of a 1-mm tumor irradiated with a 24-MeV beam receives the prescribed dose. The analytical dose deviations from the prescribed dose remain within the dose tolerances stated by report 62 of the International Commission on Radiation Units and Measurements for all tested configurations. In addition, the gamma index maps show that the highly constrained targeting accuracy of 0.1 mm for mouse irradiation leads to a significant disagreement between Geant4 and the reference. This simulated treatment planning is nevertheless compatible with a targeting accuracy exceeding 0.2 mm, corresponding to rat and rabbit irradiations. Good dose accuracy for millimetric tumors is achieved with the analytical calculation used in this work. These volume sizes are typical in mouse

Health effects of low doses at low dose rates: dose-response relationship modeling in a cohort of workers of the nuclear industry; Effets sanitaires des faibles doses a faibles debits de dose: modelisation de la relation dose-reponse dans une cohorte de travailleurs du nucleaire

Energy Technology Data Exchange (ETDEWEB)

Metz-Flamant, Camille

2011-09-19

The aim of this thesis is to contribute to a better understanding of the health effects of chronic external low doses of ionising radiation. This work is based on the French cohort of CEA-AREVA NC nuclear workers. The mains stages of this thesis were (1) conducting a review of epidemiological studies on nuclear workers, (2) completing the database and performing a descriptive analysis of the cohort, (3) quantifying risk by different statistical methods and (4) modelling the exposure-time-risk relationship. The cohort includes monitored workers employed more than one year between 1950 and 1994 at CEA or AREVA NC companies. Individual annual external exposure, history of work, vital status and causes of death were reconstructed for each worker. Standardized mortality ratios using French national mortality rates as external reference were computed. Exposure-risk analysis was conducted in the cohort using the linear excess relative risk model, based on both Poisson regression and Cox model. Time dependent modifying factors were investigated by adding an interaction term in the model or by using exposure time windows. The cohort includes 36, 769 workers, followed-up until age 60 in average. During the 1968- 2004 period, 5, 443 deaths, 2, 213 cancers, 62 leukemia and 1, 314 cardiovascular diseases were recorded. Among the 57% exposed workers, the mean cumulative dose was 21.5 milli-sieverts (mSv). A strong Healthy Worker Effect is observed in the cohort. Significant elevated risks of pleura cancer and melanoma deaths were observed in the cohort but not associated with dose. No significant association was observed with solid cancers, lung cancer and cardiovascular diseases. A significant dose-response relationship was observed for leukemia excluding chronic lymphatic leukemia, mainly for doses received less than 15 years before and for yearly dose rates higher than 10 mSv. This PhD work contributes to the evaluation of risks associated to chronic external radiation

A comparison of newborn stylized and tomographic models for dose assessment in paediatric radiology

International Nuclear Information System (INIS)

Staton, R J; Pazik, F D; Nipper, J C; Williams, J L; Bolch, W E

2003-01-01

Establishment of organ doses from diagnostic and interventional examinations is a key component to quantifying the radiation risks from medical exposures and for formulating corresponding dose-reduction strategies. Radiation transport models of human anatomy provide a convenient method for simulating radiological examinations. At present, two classes of models exist: stylized mathematical models and tomographic voxel models. In the present study, organ dose comparisons are made for projection radiographs of both a stylized and a tomographic model of the newborn patient. Sixteen separate radiographs were simulated for each model at x-ray technique factors typical of newborn examinations: chest, abdomen, thorax and head views in the AP, PA, left LAT and right LAT projection orientation. For AP and PA radiographs of the torso (chest, abdomen and thorax views), the effective dose assessed for the tomographic model exceeds that for the stylized model with per cent differences ranging from 19% (AP abdominal view) to 43% AP chest view. In contrast, the effective dose for the stylized model exceeds that for the tomographic model for all eight lateral views including those of the head, with per cent differences ranging from 9% (LLAT chest view) to 51% (RLAT thorax view). While organ positioning differences do exist between the models, a major factor contributing to differences in effective dose is the models' exterior trunk shape. In the tomographic model, a more elliptical shape is seen thus providing for less tissue shielding for internal organs in the AP and PA directions, with corresponding increased tissue shielding in the lateral directions. This observation is opposite of that seen in comparisons of stylized and tomographic models of the adult

The ecosystem models used for dose assessments in SR-Can

Energy Technology Data Exchange (ETDEWEB)

Avila, Rodolfo [Facilia AB, Bromma (Sweden)

2006-11-15

The estimation of doses to humans in the main scenarios considered in SR-Can is carried out by multiplying the radionuclide releases to the biosphere by Landscape Dose Factors (LDF), which provide estimates of doses incurred by unit releases of activity of a specific radionuclide to the landscape. The landscape models considered in deriving the LDFs consist of a set of interconnected ecosystem models of different types, including aquatic and terrestrial ecosystems. Aquatic ecosystems comprise the sea, lakes and rivers. The terrestrial ecosystems include agricultural lands, forests and mires. In this report dose conversion factor for each individual ecosystem are reported. Two release cases are considered in the report: a constant unit release rate during 10,000 years and a pulse release, i.e. a unit release during one year. For deriving the LDF values, at each considered time period an ecosystem model is assigned to each landscape object, according to the projected succession of ecosystems in the objects. The applied ecosystem models have been described elsewhere, but some modifications have been made which are described in this report. The main modifications applied to the models are to consider releases through bottom sediments and to consider upstream fluxes for the estimation of the fluxes of radionuclides between the different landscape objects. To facilitate calculations of the radionuclide concentrations in the ingested food, aggregated transfer factors are derived for each ecosystem type. These relate the radionuclide concentrations in the edible carbon production in different ecosystem types to the radionuclide concentrations in the main environmental substrates of the ecosystems, i.e. the water in aquatic ecosystems and the soil in the terrestrial ecosystems. The report provides a description of the methods applied for the derivation of aggregated transfer factors for each ecosystem type and for irrigation. These factors are applicable for situations of

The ecosystem models used for dose assessments in SR-Can

International Nuclear Information System (INIS)

Avila, Rodolfo

2006-11-01

The estimation of doses to humans in the main scenarios considered in SR-Can is carried out by multiplying the radionuclide releases to the biosphere by Landscape Dose Factors (LDF), which provide estimates of doses incurred by unit releases of activity of a specific radionuclide to the landscape. The landscape models considered in deriving the LDFs consist of a set of interconnected ecosystem models of different types, including aquatic and terrestrial ecosystems. Aquatic ecosystems comprise the sea, lakes and rivers. The terrestrial ecosystems include agricultural lands, forests and mires. In this report dose conversion factor for each individual ecosystem are reported. Two release cases are considered in the report: a constant unit release rate during 10,000 years and a pulse release, i.e. a unit release during one year. For deriving the LDF values, at each considered time period an ecosystem model is assigned to each landscape object, according to the projected succession of ecosystems in the objects. The applied ecosystem models have been described elsewhere, but some modifications have been made which are described in this report. The main modifications applied to the models are to consider releases through bottom sediments and to consider upstream fluxes for the estimation of the fluxes of radionuclides between the different landscape objects. To facilitate calculations of the radionuclide concentrations in the ingested food, aggregated transfer factors are derived for each ecosystem type. These relate the radionuclide concentrations in the edible carbon production in different ecosystem types to the radionuclide concentrations in the main environmental substrates of the ecosystems, i.e. the water in aquatic ecosystems and the soil in the terrestrial ecosystems. The report provides a description of the methods applied for the derivation of aggregated transfer factors for each ecosystem type and for irrigation. These factors are applicable for situations of

Modeling estimates of the effect of acid rain on background radiation dose.

Science.gov (United States)

Sheppard, S C; Sheppard, M I

1988-06-01

Acid rain causes accelerated mobilization of many materials in soils. Natural and anthropogenic radionuclides, especially 226Ra and 137Cs, are among these materials. Okamoto is apparently the only researcher to date who has attempted to quantify the effect of acid rain on the "background" radiation dose to man. He estimated an increase in dose by a factor of 1.3 following a decrease in soil pH of 1 unit. We reviewed literature that described the effects of changes in pH on mobility and plant uptake of Ra and Cs. Generally, a decrease in soil pH by 1 unit will increase mobility and plant uptake by factors of 2 to 7. Thus, Okamoto's dose estimate may be too low. We applied several simulation models to confirm Okamoto's ideas, with most emphasis on an atmospherically driven soil model that predicts water and nuclide flow through a soil profile. We modeled a typical, acid-rain sensitive soil using meteorological data from Geraldton, Ontario. The results, within the range of effects on the soil expected from acidification, showed essentially direct proportionality between the mobility of the nuclides and dose. This supports some of the assumptions invoked by Okamoto. We conclude that a decrease in pH of 1 unit may increase the mobility of Ra and Cs by a factor of 2 or more. Our models predict that this will lead to similar increases in plant uptake and radiological dose to man. Although health effects following such a small increase in dose have not been statistically demonstrated, any increase in dose is probably undesirable.

Modeling estimates of the effect of acid rain on background radiation dose

International Nuclear Information System (INIS)

Sheppard, S.C.; Sheppard, M.I.

1988-01-01

Acid rain causes accelerated mobilization of many materials in soils. Natural and anthropogenic radionuclides, especially 226Ra and 137Cs, are among these materials. Okamoto is apparently the only researcher to date who has attempted to quantify the effect of acid rain on the background radiation dose to man. He estimated an increase in dose by a factor of 1.3 following a decrease in soil pH of 1 unit. We reviewed literature that described the effects of changes in pH on mobility and plant uptake of Ra and Cs. Generally, a decrease in soil pH by 1 unit will increase mobility and plant uptake by factors of 2 to 7. Thus, Okamoto's dose estimate may be too low. We applied several simulation models to confirm Okamoto's ideas, with most emphasis on an atmospherically driven soil model that predicts water and nuclide flow through a soil profile. We modeled a typical, acid-rain sensitive soil using meteorological data from Geraldton, Ontario. The results, within the range of effects on the soil expected from acidification, showed essentially direct proportionality between the mobility of the nuclides and dose. This supports some of the assumptions invoked by Okamoto. We conclude that a decrease in pH of 1 unit may increase the mobility of Ra and Cs by a factor of 2 or more. Our models predict that this will lead to similar increases in plant uptake and radiological dose to man. Although health effects following such a small increase in dose have not been statistically demonstrated, any increase in dose is probably undesirable

Optimized dose distribution of a high dose rate vaginal cylinder

International Nuclear Information System (INIS)

Li Zuofeng; Liu, Chihray; Palta, Jatinder R.

1998-01-01

Purpose: To present a comparison of optimized dose distributions for a set of high-dose-rate (HDR) vaginal cylinders calculated by a commercial treatment-planning system with benchmark calculations using Monte-Carlo-calculated dosimetry data. Methods and Materials: Optimized dose distributions using both an isotropic and an anisotropic dose calculation model were obtained for a set of HDR vaginal cylinders. Mathematical optimization techniques available in the computer treatment-planning system were used to calculate dwell times and positions. These dose distributions were compared with benchmark calculations with TG43 formalism and using Monte-Carlo-calculated data. The same dwell times and positions were used for a quantitative comparison of dose calculated with three dose models. Results: The isotropic dose calculation model can result in discrepancies as high as 50%. The anisotropic dose calculation model compared better with benchmark calculations. The differences were more significant at the apex of the vaginal cylinder, which is typically used as the prescription point. Conclusion: Dose calculation models available in a computer treatment-planning system must be evaluated carefully to ensure their correct application. It should also be noted that when optimized dose distribution at a distance from the cylinder surface is calculated using an accurate dose calculation model, the vaginal mucosa dose becomes significantly higher, and therefore should be carefully monitored

Analysis of ethyl acrylate (EA) and acrylic acid (AA) residues from rat tissues following oral ea dosing

International Nuclear Information System (INIS)

Udinsky, J.R.; Frederick, C.B.

1990-01-01

Gavage dosing of rats with EA at high dose levels (100 or 200 mg/kg) has resulted in tumors at the dosing site, forestomach (FST), but no lesions of the glandular stomach (GST) or other remote tissues. Since previous in vitro studies have demonstrated that EA is very rapidly metabolized to AA and glutathione conjugates, EA and AA residues were analyzed 0-24 hr following gavage dosing of non-fasted F-344/N male rats with [1- 14 C]EA in corn oil at 10, 50, and 200 mg/kg. Analysis of total 14 C indicated that the dose solution was primarily in the FST at ≥5 min after dosing, although 14 C was detected in the GST, duodenum, and small intestine (attributed to distension of the FST and leakage from the FST to the GST). HPLC analysis of the gut contents, gut wall, liver, kidneys, lungs, and blood indicated that EA and AA could only be detected at ≥15 min in the FST and GST contents, and in the FST tissue. AA alone was detected in the GST tissue, duodenum tissue and contents, and small intestine tissue and contents. The minimum level of detection was 0.0005% of the dose. The remaining 14 C was primarily attributed to binding to the gut contents or bioincorporation of AA. The detection of EA and AA residues only in the upper gastrointestinal tract following gavage dosing is consistent with rapid detoxification of EA by hydrolysis and conjugation which prevents toxicity at sites remote form the site of dosing

Reconstructing Organophosphorus Pesticide Doses Using the Reversed Dosimetry Approach in a Simple Physiologically-Based Pharmacokinetic Model

Directory of Open Access Journals (Sweden)

Chensheng Lu

2012-01-01

Full Text Available We illustrated the development of a simple pharmacokinetic (SPK model aiming to estimate the absorbed chlorpyrifos doses using urinary biomarker data, 3,5,6-trichlorpyridinol as the model input. The effectiveness of the SPK model in the pesticide risk assessment was evaluated by comparing dose estimates using different urinary composite data. The dose estimates resulting from the first morning voids appeared to be lower than but not significantly different to those using before bedtime, lunch or dinner voids. We found similar trend for dose estimates using three different urinary composite data. However, the dose estimates using the SPK model for individual children were significantly higher than those from the conventional physiologically based pharmacokinetic (PBPK modeling using aggregate environmental measurements of chlorpyrifos as the model inputs. The use of urinary data in the SPK model intuitively provided a plausible alternative to the conventional PBPK model in reconstructing the absorbed chlorpyrifos dose.

Evaluation of Inhaled Versus Deposited Dose Using the Exponential Dose-Response Model for Inhalational Anthrax in Nonhuman Primate, Rabbit, and Guinea Pig.

Science.gov (United States)

Gutting, Bradford W; Rukhin, Andrey; Mackie, Ryan S; Marchette, David; Thran, Brandolyn

2015-05-01

The application of the exponential model is extended by the inclusion of new nonhuman primate (NHP), rabbit, and guinea pig dose-lethality data for inhalation anthrax. Because deposition is a critical step in the initiation of inhalation anthrax, inhaled doses may not provide the most accurate cross-species comparison. For this reason, species-specific deposition factors were derived to translate inhaled dose to deposited dose. Four NHP, three rabbit, and two guinea pig data sets were utilized. Results from species-specific pooling analysis suggested all four NHP data sets could be pooled into a single NHP data set, which was also true for the rabbit and guinea pig data sets. The three species-specific pooled data sets could not be combined into a single generic mammalian data set. For inhaled dose, NHPs were the most sensitive (relative lowest LD50) species and rabbits the least. Improved inhaled LD50 s proposed for use in risk assessment are 50,600, 102,600, and 70,800 inhaled spores for NHP, rabbit, and guinea pig, respectively. Lung deposition factors were estimated for each species using published deposition data from Bacillus spore exposures, particle deposition studies, and computer modeling. Deposition was estimated at 22%, 9%, and 30% of the inhaled dose for NHP, rabbit, and guinea pig, respectively. When the inhaled dose was adjusted to reflect deposited dose, the rabbit animal model appears the most sensitive with the guinea pig the least sensitive species. © 2014 Society for Risk Analysis.

Model of the dose rate for a semi industrial irradiation plant. Pt. 2

International Nuclear Information System (INIS)

Mangusi, Josefina

2004-01-01

The second stage of the model for the absorbed dose rate in air for the enclosure of a half-industrialist irradiation plant operating with cobalt-60 sources holden in plan geometry is presented. The sensibility of the model with the treatment of the support structure of the irradiator is analyzed and verified with experimental measurements with good accord. The model of the absorbed dose rate in air in the case of an interposed material between the radioactive sources and the point of interest includes in its calculation a set of secondary radioactive sources created by the Compton scattering of the primary radiation. The accord of the calculated absorbed dose rate and the experimental measured ones is good. The transit dose due to the irradiator moving until its dwell position is also modeled. The isodose curves for a set of irradiator parallel planes are also generated. (author) [es

Models for dose assessments. Models adapted to the SFR-area, Sweden

Energy Technology Data Exchange (ETDEWEB)

Karlsson, Sara; Bergstroem, U.; Meili, M. [Studsvik Eco and Safety AB, Nykoeping (Sweden)

2001-10-01

This report presents a model system created to be used to predict dose rates to the most exposed individuals in case of a long-term release of radionuclides from the Final repository for radioactive operational waste (SFR) in Forsmark, Sweden. The system accounts for an underground point source emitting radionuclides to the biosphere,their transport and distribution in various ecosystem types, their uptake by various biota, and calculation of doses to man from a multitude of exposure pathways. Long-term aspects include the consideration of processes at geological time scales, such as land uplift and conversion of marine sediments to arable land. Model parameters are whenever possible based on local conditions and recent literature. The system has been used for simulations based on geospheric releases varying over time of a mixture of radionuclides. Here, the models have been subjected to various test scenarios, including different radionuclide entry points and sorption properties. Radionuclides released from SFR are efficiently diluted to low concentrations in the water of the coastal model. A large fraction of the nuclides leave the Model Area quickly as a consequence of the rapid water turnover. The total amount of radionuclides in water is about the same independent of particle affinity (K{sub d} ), and at most some percents of the amounts retained in the sediments for some time. The latter is also true for the lake model when releases of radionuclides to the water is simulated. The role of sediments as a radionuclide source seems of minor importance in lakes at least for long-term radiation doses. Modelling the sediments as a source of radionuclides most of the 'low K{sub d} radionuclides' will leave the lake whereas the 'high K{sub d} nuclides' are still present within the deeper sediments after 1 000 years. The amount of 'low K{sub d} radionuclides' present in the water and on suspended matter are about 8x10{sup -5} of the

Models for dose assessments. Models adapted to the SFR-area, Sweden

International Nuclear Information System (INIS)

Karlsson, Sara; Bergstroem, U.; Meili, M.

2001-10-01

This report presents a model system created to be used to predict dose rates to the most exposed individuals in case of a long-term release of radionuclides from the Final repository for radioactive operational waste (SFR) in Forsmark, Sweden. The system accounts for an underground point source emitting radionuclides to the biosphere,their transport and distribution in various ecosystem types, their uptake by various biota, and calculation of doses to man from a multitude of exposure pathways. Long-term aspects include the consideration of processes at geological time scales, such as land uplift and conversion of marine sediments to arable land. Model parameters are whenever possible based on local conditions and recent literature. The system has been used for simulations based on geospheric releases varying over time of a mixture of radionuclides. Here, the models have been subjected to various test scenarios, including different radionuclide entry points and sorption properties. Radionuclides released from SFR are efficiently diluted to low concentrations in the water of the coastal model. A large fraction of the nuclides leave the Model Area quickly as a consequence of the rapid water turnover. The total amount of radionuclides in water is about the same independent of particle affinity (K d ), and at most some percents of the amounts retained in the sediments for some time. The latter is also true for the lake model when releases of radionuclides to the water is simulated. The role of sediments as a radionuclide source seems of minor importance in lakes at least for long-term radiation doses. Modelling the sediments as a source of radionuclides most of the 'low K d radionuclides' will leave the lake whereas the 'high K d nuclides' are still present within the deeper sediments after 1 000 years. The amount of 'low K d radionuclides' present in the water and on suspended matter are about 8x10 -5 of the initial inventory in the sediments. For 'high K d nuclides

Mid-ventilation position planning: Optimal model for dose distribution in lung tumour

International Nuclear Information System (INIS)

Benchalal, M.; Leseur, J.; Chajon, E.; Cazoulat, G.; Haigron, P.; Simon, A.; Bellec, J.; Lena, H.; Crevoisier, R. de

2012-01-01

Purpose. - The dose distribution for lung tumour is estimated using a 3D-CT scan, and since a person breathes while the images are captured, the dose distribution doesn't reflect the reality. A 4D-CT scan integrates the motion of the tumour during breathing and, therefore, provides us with important information regarding tumour's motion in all directions, the motion volume (ITV) and the time-weighted average position (MVP). Patient and methods. - Based on these two concepts, we have estimated, for a lung carcinoma case a 3D dose distribution from a 3D-CT scan, and a 4D dose distribution from a 4-D CT scan. To this, we have applied a non-rigid registration to estimate the cumulative dose. Results. - Our study shows that the 4D dose estimation of the GTV is almost the same when made using MVP and ITV concepts, but sparring of the healthy lung is better done using the MPV model (MVP), as compared to the ITV model. This improvement of the therapeutic index allows, from a projection on the theoretical maximal dose to PTV (strictly restricted to doses for the lungs and the spinal cord), for an increase of about 11% on the total dose (maximal dose of 86 Gy for the ITV and 96 Gy for the MVP). Conclusion. - Further studies with more patients are needed to confirm our data. (authors)

A deterministic partial differential equation model for dose calculation in electron radiotherapy.

Science.gov (United States)

Duclous, R; Dubroca, B; Frank, M

2010-07-07

High-energy ionizing radiation is a prominent modality for the treatment of many cancers. The approaches to electron dose calculation can be categorized into semi-empirical models (e.g. Fermi-Eyges, convolution-superposition) and probabilistic methods (e.g.Monte Carlo). A third approach to dose calculation has only recently attracted attention in the medical physics community. This approach is based on the deterministic kinetic equations of radiative transfer. We derive a macroscopic partial differential equation model for electron transport in tissue. This model involves an angular closure in the phase space. It is exact for the free streaming and the isotropic regime. We solve it numerically by a newly developed HLLC scheme based on Berthon et al (2007 J. Sci. Comput. 31 347-89) that exactly preserves the key properties of the analytical solution on the discrete level. We discuss several test cases taken from the medical physics literature. A test case with an academic Henyey-Greenstein scattering kernel is considered. We compare our model to a benchmark discrete ordinate solution. A simplified model of electron interactions with tissue is employed to compute the dose of an electron beam in a water phantom, and a case of irradiation of the vertebral column. Here our model is compared to the PENELOPE Monte Carlo code. In the academic example, the fluences computed with the new model and a benchmark result differ by less than 1%. The depths at half maximum differ by less than 0.6%. In the two comparisons with Monte Carlo, our model gives qualitatively reasonable dose distributions. Due to the crude interaction model, these so far do not have the accuracy needed in clinical practice. However, the new model has a computational cost that is less than one-tenth of the cost of a Monte Carlo simulation. In addition, simulations can be set up in a similar way as a Monte Carlo simulation. If more detailed effects such as coupled electron-photon transport, bremsstrahlung

A deterministic partial differential equation model for dose calculation in electron radiotherapy

Science.gov (United States)

Duclous, R.; Dubroca, B.; Frank, M.

2010-07-01

High-energy ionizing radiation is a prominent modality for the treatment of many cancers. The approaches to electron dose calculation can be categorized into semi-empirical models (e.g. Fermi-Eyges, convolution-superposition) and probabilistic methods (e.g. Monte Carlo). A third approach to dose calculation has only recently attracted attention in the medical physics community. This approach is based on the deterministic kinetic equations of radiative transfer. We derive a macroscopic partial differential equation model for electron transport in tissue. This model involves an angular closure in the phase space. It is exact for the free streaming and the isotropic regime. We solve it numerically by a newly developed HLLC scheme based on Berthon et al (2007 J. Sci. Comput. 31 347-89) that exactly preserves the key properties of the analytical solution on the discrete level. We discuss several test cases taken from the medical physics literature. A test case with an academic Henyey-Greenstein scattering kernel is considered. We compare our model to a benchmark discrete ordinate solution. A simplified model of electron interactions with tissue is employed to compute the dose of an electron beam in a water phantom, and a case of irradiation of the vertebral column. Here our model is compared to the PENELOPE Monte Carlo code. In the academic example, the fluences computed with the new model and a benchmark result differ by less than 1%. The depths at half maximum differ by less than 0.6%. In the two comparisons with Monte Carlo, our model gives qualitatively reasonable dose distributions. Due to the crude interaction model, these so far do not have the accuracy needed in clinical practice. However, the new model has a computational cost that is less than one-tenth of the cost of a Monte Carlo simulation. In addition, simulations can be set up in a similar way as a Monte Carlo simulation. If more detailed effects such as coupled electron-photon transport, bremsstrahlung

Modification and validation of an analytical source model for external beam radiotherapy Monte Carlo dose calculations

Energy Technology Data Exchange (ETDEWEB)

Davidson, Scott E., E-mail: sedavids@utmb.edu [Radiation Oncology, The University of Texas Medical Branch, Galveston, Texas 77555 (United States); Cui, Jing [Radiation Oncology, University of Southern California, Los Angeles, California 90033 (United States); Kry, Stephen; Ibbott, Geoffrey S.; Followill, David S. [Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030 (United States); Deasy, Joseph O. [Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York, New York 10065 (United States); Vicic, Milos [Department of Applied Physics, University of Belgrade, Belgrade 11000 (Serbia); White, R. Allen [Bioinformatics and Computational Biology, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030 (United States)

2016-08-15

Purpose: A dose calculation tool, which combines the accuracy of the dose planning method (DPM) Monte Carlo code and the versatility of a practical analytical multisource model, which was previously reported has been improved and validated for the Varian 6 and 10 MV linear accelerators (linacs). The calculation tool can be used to calculate doses in advanced clinical application studies. One shortcoming of current clinical trials that report dose from patient plans is the lack of a standardized dose calculation methodology. Because commercial treatment planning systems (TPSs) have their own dose calculation algorithms and the clinical trial participant who uses these systems is responsible for commissioning the beam model, variation exists in the reported calculated dose distributions. Today’s modern linac is manufactured to tight specifications so that variability within a linac model is quite low. The expectation is that a single dose calculation tool for a specific linac model can be used to accurately recalculate dose from patient plans that have been submitted to the clinical trial community from any institution. The calculation tool would provide for a more meaningful outcome analysis. Methods: The analytical source model was described by a primary point source, a secondary extra-focal source, and a contaminant electron source. Off-axis energy softening and fluence effects were also included. The additions of hyperbolic functions have been incorporated into the model to correct for the changes in output and in electron contamination with field size. A multileaf collimator (MLC) model is included to facilitate phantom and patient dose calculations. An offset to the MLC leaf positions was used to correct for the rudimentary assumed primary point source. Results: Dose calculations of the depth dose and profiles for field sizes 4 × 4 to 40 × 40 cm agree with measurement within 2% of the maximum dose or 2 mm distance to agreement (DTA) for 95% of the data

Validation and uncertainty analysis of a pre-treatment 2D dose prediction model

Science.gov (United States)

Baeza, Jose A.; Wolfs, Cecile J. A.; Nijsten, Sebastiaan M. J. J. G.; Verhaegen, Frank

2018-02-01

Independent verification of complex treatment delivery with megavolt photon beam radiotherapy (RT) has been effectively used to detect and prevent errors. This work presents the validation and uncertainty analysis of a model that predicts 2D portal dose images (PDIs) without a patient or phantom in the beam. The prediction model is based on an exponential point dose model with separable primary and secondary photon fluence components. The model includes a scatter kernel, off-axis ratio map, transmission values and penumbra kernels for beam-delimiting components. These parameters were derived through a model fitting procedure supplied with point dose and dose profile measurements of radiation fields. The model was validated against a treatment planning system (TPS; Eclipse) and radiochromic film measurements for complex clinical scenarios, including volumetric modulated arc therapy (VMAT). Confidence limits on fitted model parameters were calculated based on simulated measurements. A sensitivity analysis was performed to evaluate the effect of the parameter uncertainties on the model output. For the maximum uncertainty, the maximum deviating measurement sets were propagated through the fitting procedure and the model. The overall uncertainty was assessed using all simulated measurements. The validation of the prediction model against the TPS and the film showed a good agreement, with on average 90.8% and 90.5% of pixels passing a (2%,2 mm) global gamma analysis respectively, with a low dose threshold of 10%. The maximum and overall uncertainty of the model is dependent on the type of clinical plan used as input. The results can be used to study the robustness of the model. A model for predicting accurate 2D pre-treatment PDIs in complex RT scenarios can be used clinically and its uncertainties can be taken into account.

Dose coefficients in pediatric and adult abdominopelvic CT based on 100 patient models

Science.gov (United States)

Tian, Xiaoyu; Li, Xiang; Segars, W. Paul; Frush, Donald P.; Paulson, Erik K.; Samei, Ehsan

2013-12-01

Recent studies have shown the feasibility of estimating patient dose from a CT exam using CTDIvol-normalized-organ dose (denoted as h), DLP-normalized-effective dose (denoted as k), and DLP-normalized-risk index (denoted as q). However, previous studies were limited to a small number of phantom models. The purpose of this work was to provide dose coefficients (h, k, and q) across a large number of computational models covering a broad range of patient anatomy, age, size percentile, and gender. The study consisted of 100 patient computer models (age range, 0 to 78 y.o.; weight range, 2-180 kg) including 42 pediatric models (age range, 0 to 16 y.o.; weight range, 2-80 kg) and 58 adult models (age range, 18 to 78 y.o.; weight range, 57-180 kg). Multi-detector array CT scanners from two commercial manufacturers (LightSpeed VCT, GE Healthcare; SOMATOM Definition Flash, Siemens Healthcare) were included. A previously-validated Monte Carlo program was used to simulate organ dose for each patient model and each scanner, from which h, k, and q were derived. The relationships between h, k, and q and patient characteristics (size, age, and gender) were ascertained. The differences in conversion coefficients across the scanners were further characterized. CTDIvol-normalized-organ dose (h) showed an exponential decrease with increasing patient size. For organs within the image coverage, the average differences of h across scanners were less than 15%. That value increased to 29% for organs on the periphery or outside the image coverage, and to 8% for distributed organs, respectively. The DLP-normalized-effective dose (k) decreased exponentially with increasing patient size. For a given gender, the DLP-normalized-risk index (q) showed an exponential decrease with both increasing patient size and patient age. The average differences in k and q across scanners were 8% and 10%, respectively. This study demonstrated that the knowledge of patient information and CTDIvol/DLP values may

Dose coefficients in pediatric and adult abdominopelvic CT based on 100 patient models

International Nuclear Information System (INIS)

Tian, Xiaoyu; Samei, Ehsan; Li, Xiang; Segars, W Paul; Frush, Donald P; Paulson, Erik K

2013-01-01

Recent studies have shown the feasibility of estimating patient dose from a CT exam using CTDI vol -normalized-organ dose (denoted as h), DLP-normalized-effective dose (denoted as k), and DLP-normalized-risk index (denoted as q). However, previous studies were limited to a small number of phantom models. The purpose of this work was to provide dose coefficients (h, k, and q) across a large number of computational models covering a broad range of patient anatomy, age, size percentile, and gender. The study consisted of 100 patient computer models (age range, 0 to 78 y.o.; weight range, 2–180 kg) including 42 pediatric models (age range, 0 to 16 y.o.; weight range, 2–80 kg) and 58 adult models (age range, 18 to 78 y.o.; weight range, 57–180 kg). Multi-detector array CT scanners from two commercial manufacturers (LightSpeed VCT, GE Healthcare; SOMATOM Definition Flash, Siemens Healthcare) were included. A previously-validated Monte Carlo program was used to simulate organ dose for each patient model and each scanner, from which h, k, and q were derived. The relationships between h, k, and q and patient characteristics (size, age, and gender) were ascertained. The differences in conversion coefficients across the scanners were further characterized. CTDI vol -normalized-organ dose (h) showed an exponential decrease with increasing patient size. For organs within the image coverage, the average differences of h across scanners were less than 15%. That value increased to 29% for organs on the periphery or outside the image coverage, and to 8% for distributed organs, respectively. The DLP-normalized-effective dose (k) decreased exponentially with increasing patient size. For a given gender, the DLP-normalized-risk index (q) showed an exponential decrease with both increasing patient size and patient age. The average differences in k and q across scanners were 8% and 10%, respectively. This study demonstrated that the knowledge of patient information and CTDI vol

Monte Carlo-based dose reconstruction in a rat model for scattered ionizing radiation investigations.

Science.gov (United States)

Kirkby, Charles; Ghasroddashti, Esmaeel; Kovalchuk, Anna; Kolb, Bryan; Kovalchuk, Olga

2013-09-01

In radiation biology, rats are often irradiated, but the precise dose distributions are often lacking, particularly in areas that receive scatter radiation. We used a non-dedicated set of resources to calculate detailed dose distributions, including doses to peripheral organs well outside of the primary field, in common rat exposure settings. We conducted a detailed dose reconstruction in a rat through an analog to the conventional human treatment planning process. The process consisted of: (i) Characterizing source properties of an X-ray irradiator system, (ii) acquiring a computed tomography (CT) scan of a rat model, and (iii) using a Monte Carlo (MC) dose calculation engine to generate the dose distribution within the rat model. We considered cranial and liver irradiation scenarios where the rest of the body was protected by a lead shield. Organs of interest were the brain, liver and gonads. The study also included paired scenarios where the dose to adjacent, shielded rats was determined as a potential control for analysis of bystander effects. We established the precise doses and dose distributions delivered to the peripheral organs in single and paired rats. Mean doses to non-targeted organs in irradiated rats ranged from 0.03-0.1% of the reference platform dose. Mean doses to the adjacent rat peripheral organs were consistent to within 10% those of the directly irradiated rat. This work provided details of dose distributions in rat models under common irradiation conditions and established an effective scenario for delivering only scattered radiation consistent with that in a directly irradiated rat.

TSD-DOSE : a radiological dose assessment model for treatment, storage, and disposal facilities

International Nuclear Information System (INIS)

Pfingston, M.

1998-01-01

In May 1991, the U.S. Department of Energy (DOE), Office of Waste Operations, issued a nationwide moratorium on shipping slightly radioactive mixed waste from DOE facilities to commercial treatment, storage, and disposal (TSD) facilities. Studies were subsequently conducted to evaluate the radiological impacts associated with DOE's prior shipments through DOE's authorized release process under DOE Order 5400.5. To support this endeavor, a radiological assessment computer code--TSD-DOSE (Version 1.1)--was developed and issued by DOE in 1997. The code was developed on the basis of detailed radiological assessments performed for eight commercial hazardous waste TSD facilities. It was designed to utilize waste-specific and site-specific data to estimate potential radiological doses to on-site workers and the off-site public from waste handling operations at a TSD facility. The code has since been released for use by DOE field offices and was recently used by DOE to evaluate the release of septic waste containing residual radioactive material to a TSD facility licensed under the Resource Conservation and Recovery Act. Revisions to the code were initiated in 1997 to incorporate comments received from users and to increase TSD-DOSE's capability, accuracy, and flexibility. These updates included incorporation of the method used to estimate external radiation doses from DOE's RESRAD model and expansion of the source term to include 85 radionuclides. In addition, a detailed verification and benchmarking analysis was performed

Modelling of Biota Dose Effects. Report of Working Group 6 Biota Dose Effects Modelling of EMRAS II Topical Heading Reference Approaches for Biota Dose Assessment. Environmental Modelling for RAdiation Safety (EMRAS II) Programme

International Nuclear Information System (INIS)

2014-07-01

Environmental assessment models are used for evaluating the radiological impact of actual and potential releases of radionuclides to the environment. They are essential tools for use in the regulatory control of routine discharges to the environment and in planning the measures to be taken in the event of accidental releases. They are also used for predicting the impact of releases which may occur far into the future, for example, from underground radioactive waste repositories. It is important to verify, to the extent possible, the reliability of the predictions of such models by a comparison with measured values in the environment or with the predictions of other models. The IAEA has been organizing programmes on international model testing since the 1980s. These programmes have contributed to a general improvement in models, in the transfer of data and in the capabilities of modellers in Member States. IAEA publications on this subject over the past three decades demonstrate the comprehensive nature of the programmes and record the associated advances which have been made. From 2009 to 2011, the IAEA organized a project entitled Environmental Modelling for RAdiation Safety (EMRAS II), which concentrated on the improvement of environmental transfer models and the development of reference approaches to estimate the radiological impacts on humans, as well as on flora and fauna, arising from radionuclides in the environment. Different aspects were addressed by nine working groups covering three themes: reference approaches for human dose assessment, reference approaches for biota dose assessment and approaches for addressing emergency situations. This publication describes the work of the Biota Effects Modelling Working Group

Modelling of Biota Dose Effects. Report of Working Group 6 Biota Dose Effects Modelling of EMRAS II Topical Heading Reference Approaches for Biota Dose Assessment. Environmental Modelling for RAdiation Safety (EMRAS II) Programme

Energy Technology Data Exchange (ETDEWEB)

NONE

2014-07-15

Environmental assessment models are used for evaluating the radiological impact of actual and potential releases of radionuclides to the environment. They are essential tools for use in the regulatory control of routine discharges to the environment and in planning the measures to be taken in the event of accidental releases. They are also used for predicting the impact of releases which may occur far into the future, for example, from underground radioactive waste repositories. It is important to verify, to the extent possible, the reliability of the predictions of such models by a comparison with measured values in the environment or with the predictions of other models. The IAEA has been organizing programmes on international model testing since the 1980s. These programmes have contributed to a general improvement in models, in the transfer of data and in the capabilities of modellers in Member States. IAEA publications on this subject over the past three decades demonstrate the comprehensive nature of the programmes and record the associated advances which have been made. From 2009 to 2011, the IAEA organized a project entitled Environmental Modelling for RAdiation Safety (EMRAS II), which concentrated on the improvement of environmental transfer models and the development of reference approaches to estimate the radiological impacts on humans, as well as on flora and fauna, arising from radionuclides in the environment. Different aspects were addressed by nine working groups covering three themes: reference approaches for human dose assessment, reference approaches for biota dose assessment and approaches for addressing emergency situations. This publication describes the work of the Biota Effects Modelling Working Group.

A model to incorporate organ deformation in the evaluation of dose/volume relationship

International Nuclear Information System (INIS)

Yan, D.; Jaffray, D.; Wong, J.; Brabbins, D.; Martinez, A. A.

1997-01-01

Purpose: Measurements of internal organ motion have demonstrated that daily organ deformation exists during the course of radiation treatment. However, a model to evaluate the resultant dose delivered to a daily deformed organ remains a difficult challenge. Current methods which model such organ deformation as rigid body motion in the dose calculation for treatment planning evaluation are incorrect and misleading. In this study, a new model for treatment planning evaluation is introduced which incorporates patient specific information of daily organ deformation and setup variation. The model was also used to retrospectively analyze the actual treatment data measured using daily CT scans for 5 patients with prostate treatment. Methods and Materials: The model assumes that for each patient, the organ of interest can be measured during the first few treatment days. First, the volume of each organ is delineated from each of the daily measurements and cumulated in a 3D bit-map. A tissue occupancy distribution is then constructed with the 50% isodensity representing the mean, or effective, organ volume. During the course of treatment, each voxel in the effective organ volume is assumed to move inside a local 3D neighborhood with a specific distribution function. The neighborhood and the distribution function are deduced from the positions and shapes of the organ in the first few measurements using the biomechanics model of viscoelastic body. For each voxel, the local distribution function is then convolved with the spatial dose distribution. The latter includes also the variation in dose due to daily setup error. As a result, the cumulative dose to the voxel incorporates the effects of daily setup variation and organ deformation. A ''variation adjusted'' dose volume histogram, aDVH, for the effective organ volume can then be constructed for the purpose of treatment evaluation and optimization. Up to 20 daily CT scans and daily portal images for 5 patients with prostate

Optimization of dose radiation and image quality on computed tomography of thorax in adult women

Energy Technology Data Exchange (ETDEWEB)

Cruz Z, G. R.; Casian C, G. [Hospital Juarez de Mexico, Av. IPN No. 5160, 07760 Mexico D. F. (Mexico); Gaona, E.; Franco E, J. G.; Molina F, N., E-mail: gaen1310@correo.xoc.uam.mx [Universidad Autonoma Metropolitana, Unidad Xochimilco, Calz. del Hueso 1100, 04960 Mexico D. F. (Mexico)

2015-10-15

Full text: The objective of the study is the optimization of the dose (Dlp) and image quality in the exploration of adult women in studies of thorax with computed tomography (CT). The CT is a technique of exploration with high radiation doses to patients with an increase of the risk factors of developing cancer in the future, but X-rays are a very important medical diagnostic tool. We performed a retrospective survey of 50 female patients who had thorax tomography using the automatic protocol established by the manufacturer, a database of dose (Dlp), measures of patient A P and radiological parameters such as kV and m A was obtained. Subsequently, we carry out the prospective study with 30 patients with prescription of thorax tomography, scans were conducted with CT with reduced doses using manual techniques protocol of exploration while maintaining diagnostic image quality. The results show that the prospective study patients received doses lower than 30% on average. In general the dose patients were within the confidence interval of 95% of the levels of diagnostic reference (DRL) adopted by the European Community for CT and the most common value is 400 Dlp for thorax. Comparative image quality study was conducted using the protocol of the manufacturer and the manual protocol and image quality was diagnostic after dose reduction up to 30%. The reduction of radiation dose in female patients in studies of thorax CT helps to reduce risk factors of developing cancer later in life. A thorax tomography study includes the fibro-glandular tissue of the breast which is very sensitive to stochastic effects of radiation. (Author)