Zeitschriften und Ausgaben

Volumen 28 (2022): Heft 3 (September 2022)

Volumen 28 (2022): Heft 2 (June 2022)

Volumen 28 (2022): Heft 1 (March 2022)

Volumen 27 (2021): Heft 4 (December 2021)

Volumen 27 (2021): Heft 3 (September 2021)

Volumen 27 (2021): Heft 2 (June 2021)

Volumen 27 (2021): Heft 1 (March 2021)

Volumen 26 (2020): Heft 4 (December 2020)

Volumen 26 (2020): Heft 3 (September 2020)

Volumen 26 (2020): Heft 2 (June 2020)

Volumen 26 (2020): Heft 1 (March 2020)

Volumen 25 (2019): Heft 4 (December 2019)

Volumen 25 (2019): Heft 3 (September 2019)

Volumen 25 (2019): Heft 2 (June 2019)

Volumen 25 (2019): Heft 1 (March 2019)

Volumen 24 (2018): Heft 4 (December 2018)

Volumen 24 (2018): Heft 3 (September 2018)

Volumen 24 (2018): Heft 2 (June 2018)

Volumen 24 (2018): Heft 1 (March 2018)

Volumen 23 (2017): Heft 4 (December 2017)

Volumen 23 (2017): Heft 3 (September 2017)

Volumen 23 (2017): Heft 2 (June 2017)

Volumen 23 (2017): Heft 1 (March 2017)

Volumen 22 (2016): Heft 4 (December 2016)

Volumen 22 (2016): Heft 3 (September 2016)

Volumen 22 (2016): Heft 2 (June 2016)

Volumen 22 (2016): Heft 1 (March 2016)

Volumen 21 (2015): Heft 1 (December 2015)

Volumen 20 (2014): Heft 1 (March 2014)

Volumen 19 (2013): Heft 2 (December 2013)

Volumen 19 (2013): Heft 1 (March 2013)

Volumen 18 (2012): Heft 2 (June 2012)

Volumen 18 (2012): Heft 1 (March 2012)

Volumen 17 (2011): Heft 4 (December 2011)

Volumen 17 (2011): Heft 3 (September 2011)

Volumen 17 (2011): Heft 2 (June 2011)

Volumen 17 (2011): Heft 1 (March 2011)

Volumen 16 (2010): Heft 2 (June 2010)

Volumen 16 (2010): Heft 1 (March 2010)

Volumen 15 (2009): Heft 4 (December 2009)

Volumen 15 (2009): Heft 3 (September 2009)

Volumen 15 (2009): Heft 2 (June 2009)

Volumen 15 (2009): Heft 1 (March 2009)

Volumen 14 (2008): Heft 4 (December 2008)

Volumen 14 (2008): Heft 3 (September 2008)

Volumen 14 (2008): Heft 2 (June 2008)

Volumen 14 (2008): Heft 1 (March 2008)

Volumen 13 (2007): Heft 4 (December 2007)

Volumen 13 (2007): Heft 3 (September 2007)

Volumen 13 (2007): Heft 2 (June 2007)

Volumen 13 (2007): Heft 1 (March 2007)

Zeitschriftendaten
Format
Zeitschrift
eISSN
1898-0309
Erstveröffentlichung
30 Dec 2008
Erscheinungsweise
4 Hefte pro Jahr
Sprachen
Englisch

Suche

Volumen 25 (2019): Heft 2 (June 2019)

Zeitschriftendaten
Format
Zeitschrift
eISSN
1898-0309
Erstveröffentlichung
30 Dec 2008
Erscheinungsweise
4 Hefte pro Jahr
Sprachen
Englisch

Suche

10 Artikel
access type Uneingeschränkter Zugang

A literature review on multimodality molecular imaging nanoprobes for cancer detection

Online veröffentlicht: 18 Jun 2019
Seitenbereich: 57 - 68

Zusammenfassung

Abstract

Molecular imaging techniques using nanoparticles have significant potential to be widely used for the detection of various types of cancers. Nowadays, there has been an increased focus on developing novel nanoprobes as molecular imaging contrast enhancement agents in nanobiomedicine. The purpose of this review article is to summarize the use of a variety of nanoprobes and their current achievements in accurate cancer imaging and effective treatment. Nanoprobes are rapidly becoming potential tools for cancer diagnosis by using novel molecular imaging modalities such as Ultrasound (US) imaging, Computerized Tomography (CT), Single Photon Emission Tomography (SPECT) and Positron Emission Tomography (PET), Magnetic Resonance Imaging (MRI), and Optical Imaging. These imaging modalities may facilitate earlier and more accurate diagnosis and staging the most of cancers.

Schlüsselwörter

  • molecular imaging
  • nanoprobes
  • cancer
  • nanobiomedicine
access type Uneingeschränkter Zugang

Study the Anti-MUC1 antibody-based iron oxide nanoparticles on three-dimension spheroid and breast cancer (MCF-7) cell imaging

Online veröffentlicht: 18 Jun 2019
Seitenbereich: 69 - 77

Zusammenfassung

Abstract

Non-invasive methods for breast cancer detection in early stages may help to increase the survival rate of patients. This study aimed to evaluate the application of Anti-MUC1 antibody-based iron oxide nanoparticle (SPIONs-C595) which was assessed in vivo as a molecular imaging probe for breast cancer (MCF-7) detection using MRI. Nine groups of female NRC NU/Nu mice (each group of 3), 6 to 8 weeks old were used and MCF-7 cells were injected subcutaneously into both flanks of nude mice. After two weeks the mice received an intravenous injection of different concentrations of SPIONs-C595. The uptake ability of SPIONs-C595 on three-dimension (3D) macrostructure is exploited a modified hanging drop method using Prussian blue for MCF-7 cells. The iron content was measured in liver, kidney, spleen, and tumor. The MR imaging features and biodistribution of nanoprobe was also investigated. The MR images obtained from digested tumor after nanoprobe administration in different time-period revealed that enhancement of T1 and T2 relaxation time. Moreover, the storage stability test was shown great application and no sedimentation of nanoparticles within two months storage at 4°C. Additionally, great validation of SPIONs-C595 on the 3D spheroid of MCF-7 was observed. The biodistribution analysis showed that iron content of the spleen was more than the other studied organs. These results highlighted the feasibility of an in-vivo model for detection of breast cancer MUC1 expression. Current researches are ongoing to further enhancement of relaxation times for classification of MUC1 status using clinical specimens.

Schlüsselwörter

  • SPIONs
  • MR imaging
  • MCF-7 cells
  • C595 monoclonal antibody
access type Uneingeschränkter Zugang

Bismuth-based nanoparticles as radiosensitizer in low and high dose rate brachytherapy

Online veröffentlicht: 18 Jun 2019
Seitenbereich: 79 - 85

Zusammenfassung

Abstract

Background: Recently bismuth-based nanoparticles have attracted increasing attention as a dose amplification agent in radiation therapy due to high atomic number, high photoelectric absorption, low cost, and low toxicity.

Objectives: This study aims to calculate physical aspects of dose enhancement of bismuth-based nanoparticles in the presence of brachytherapy source by Monte Carlo simulation and an analytical method for low mono-energy. Materials and methods: After simulation and validation brachytherapy sources (Iodine-125 and Ytterbium-169) by Monte Carlo code, bismuth-based nanoparticles (bismuth, bismuth oxide, bismuth sulfide, and bismuth ferrite) were modeled in the sizes of 50 nm and 100 nm for two concentrations of 10 and 20 mg/ml. Dose enhancement factors for the bismuth-based nanoparticles were measured at both brachytherapy sources. Furthermore, the dose amplification was calculated with an analytic method at 30 keV mono-energy.

Results: Dose enhancement factor was greatest with pure bismuth nanoparticles, followed by bismuth oxide, bismuth sulfide and bismuth ferrite for both radiation source and simulation methods. The dose amplification for the bismuth-based nanoparticles increased with increasing size and concentration of nanoparticles.

Conclusion: The physical aspect dose enhancement of the nanoparticles was shown by Monte Carlo and analytic method. The results have proved bismuth-based nanoparticles deserve further study as a radiosensitizer.

Schlüsselwörter

  • bismuth-based nanoparticles
  • brachytherapy source
  • radiosensitizer
  • Monte Carlo simulation
  • dose enhancement
access type Uneingeschränkter Zugang

A Monte Carlo study on the radio-sensitization effect of gold nanoparticles in brachytherapy of prostate by 103Pd seeds

Online veröffentlicht: 18 Jun 2019
Seitenbereich: 87 - 92

Zusammenfassung

Abstract

103Pd seed is being used for prostate brachytherapy. Additionally, the dose enhancement effect of gold nanoparticles (GNP) has been reported in previous studies. The aim of this study was to characterize the dosimetric effect of gold nanoparticles in brachytherapy with a 103Pd source. Two brachytherapy seeds including 103 Pd source was simulated using MCNPX Monte Carlo code. The seeds’ models were validated by comparing the MC with reported results. Then, GNPs (10 nm in diameter) with a concentration of 7mg Au/g were simulated uniformly inside the prostate of a humanoid computational phantom. Additionally, the dose enhancement factor (DEF) of nanoparticles was calculated for both modeled brachytherapy seeds. A good agreement was found between the MC calculated and the reported dosimetric parameters. For both seeds, an average DEF of 23% was obtained in tumor volume for prostate brachytherapy. The application of GNPs in conjunction with 103Pd seed in brachytherapy can enhance the delivered dose to the tumor and consequently leads to better treatment outcome.

Schlüsselwörter

  • Pd
  • prostate cancer
  • brachytherapy
  • Monte Carlo
  • gold nanoparticle
access type Uneingeschränkter Zugang

A GATE Monte Carlo model for a newly developed small animal PET scanner: the IRI-microPET

Online veröffentlicht: 18 Jun 2019
Seitenbereich: 93 - 100

Zusammenfassung

Abstract

Monte Carlo simulation is widely used in emission tomography, in order to assess image reconstruction algorithms and correction techniques, for system optimization, and study the parameters affecting the system performance. In the current study, the performance of the IRI-microPET system was simulated using the GATE Monte Carlo code and a number of performance parameters, including spatial resolution, scatter fraction, sensitivity, RMS contrast, and signal-to-noise ratio, evaluated and compared to the corresponding measured values. The results showed an excellent agreement between simulated and measured data: The experimental and simulated spatial resolutions (radial) for 18F in the center of the AFOV were 1.81 mm and 1.65 mm, respectively. The difference between the experimental and simulated sensitivities of the system was <7%. Simulated and experimental scatter fractions differed less than 9% for the mouse phantom in different timing windows. The validation study of the image quality indicated a good agreement in RMS contrast and signal-to-noise ratio. Also, system performance was compared with the two available commercial scanners which were simulated using GATE code. In conclusion, the assessment of the Monte Carlo modeling of the IRI-microPET system reveals that the GATE code is a flexible and accurate tool for describing the response of an animal PET system.

Schlüsselwörter

  • GATE
  • Monte Carlo
  • simulation
  • IRI-microPET
  • performance
access type Uneingeschränkter Zugang

The effect of SSD, Field size, Energy and Detector type for Relative Output Factor measurement in small photon beams as compared with Monte Carlo simulation

Online veröffentlicht: 18 Jun 2019
Seitenbereich: 101 - 110

Zusammenfassung

Abstract

Introduction: Small fields photon dosimetry is associated with many problems. Using the right detector for measurement plays a fundamental role. This study investigated the measurement of relative output for small photon fields with different detectors. It was investigated for three-photon beam energies at SSDs of 90, 95, 100 and 110 cm. As a benchmark, the Monte Carlo simulation was done to calculate the relative output of these small photon beams for the dose in water.

Materials and Methods: 6, 10 and 15 MV beams were delivered from a Synergy LINAC equipped with an Agility 160 multileaf collimator (MLC). A CC01 ion chamber, EFD-3G diode, PTW60019 microdiamond, EBT2 radiochromic film, and EDR2 radiographic film were used to measure the relative output of the linac. Measurements were taken in water for the CC01 ion chamber, EFD-3G diode, and the PTW60019. Films were measured in water equivalent RW3 phantom slabs. Measurements were made for 1 × 1, 2 × 2, 3 × 3, 4 × 4, 5 × 5 and a reference field of 10 × 10 cm2. Field sizes were defined at 100cm SSD. Relative output factors were also compared with Monte Carlo (MC) simulation of the LINAC and a water phantom model. The influence of voxel size was also investigated for relative output measurement. Results and Discussion: The relative output factor (ROF) increased with energy for all fields large enough to have lateral electronic equilibrium (LEE). This relation broke down as the field sizes decreased due to the onset of lateral electronic disequilibrium (LED). The high-density detector, PTW60019 gave the highest ROF for the different energies, with the less dense CC01 giving the lowest ROFs.

Conclusion: These are results compared to MC simulation, higher density detectors give higher ROF values. Relative to water, the ROF measured with the air-chamber remained virtually unchanged. The ROFs, as measured in this study showed little variation due to increased SSDs. The effect of voxel size for the Monte Carlo calculations in water does not lead to significant ROF variation over the small fields studied.

Schlüsselwörter

  • small-field dosimetry
  • relative output factor
  • electronic equilibrium
  • Monte Carlo
access type Uneingeschränkter Zugang

Feasibility study of conformal forward planned simultaneous integrated boost technique comparable to IMRT and VMAT in pelvic irradiation for locally advanced cervical cancer

Online veröffentlicht: 18 Jun 2019
Seitenbereich: 111 - 119

Zusammenfassung

Abstract

Aim: To check the feasibility of simultaneous integrated boost (SIB) using a forward planned field in field (FIF) conformal technique for the treatment of carcinoma of the cervix IIIB and compare it dosimetrically with other advanced inverse planning techniques.

Methods: In our study 33 patients of carcinoma of the cervix IIIB were planned for SIB using conformal FIF technique and they were compared with retrospectively planned IMRT and VMAT techniques. SIB using conformal FIF was planned by two different methods.

Results: The results of our study indicate that forward planned Conformal SIB techniques are comparable with inverse planned techniques dosimetrically, in terms of conformity Index, Homogeneity Index, Maximum dose, etc. The ability of FIF SIB plans to produce dose contrast in differential dose accumulation was compared and analyzed and the results were encouraging. To treat an advanced/bulky disease like Carcinoma of the Cervix IIIB in centers with large patient load, utilizing advanced techniques such as IMRT and VMAT is both technically and practically difficult. Despite VMAT’s shorter delivery time, the procedures involved are time-consuming.

Conclusion: Hence forward planned SIB techniques may be used to achieve similar dosimetric effects of IMRT and VMAT techniques without much compromise in plan quality and patient throughput for treating bulky carcinoma of the cervix IIIB cases. However, the clinical results need to be carefully compared and evaluated and reported.

Schlüsselwörter

  • forward planning
  • SIB
  • field in field
  • inverse planning
  • biological evaluation
  • carcinoma of the cervix
access type Uneingeschränkter Zugang

Effect of Changing Phantom Thickness on Helical Radiotherapy Plan: Dosimetric Analysis

Online veröffentlicht: 18 Jun 2019
Seitenbereich: 121 - 126

Zusammenfassung

Abstract

Purpose: The aim of this study is to investigate the effect of changing phantom thickness on high dose region of interest (HD_ROI) and low dose ROI’s (LW_ROI’s) doses during helical radiotherapy (RT) by utilizing Adaptive RT (ART) technique.

Materials and Methods: The cylindrical phantom (CP) is wrapped with different thickness boluses and scanned in the kilovoltage computed tomography (KVCT). HD_ROI and LW_ROI’s were created in contouring system and nine same plans (1.8 Gy/Fr) were made with images of different thicknesses CP. The point dose measurements were performed using ionization chamber in Helical Tomotherapy (HT) treatment machine. For detecting thickness reduction effect, CP was irradiated using bolus-designed plans and it was irradiated using without bolus plan. The opposite of this scenario was applied to determine the thickness increase. KVCT and megavoltage CT (MVCT) images were used for dose comparison. The HT Planned Adaptive Software was used to see the differences in the planning and verification doses at dose volume histograms (DVH).

Results: Point dose measurements showed a 4.480% dose increase in 0.5 cm depth reduction for HD_ROI. These differences reached 8.508% in 2 cm depth and 15,279% in 5 cm depth. At the same time, a dose reduction of 0.665% was determined for a 0.5cm depth increase, a dose reduction of 1.771% was determined for a 2 cm depth increase, a dose reduction of 5.202% was determined for a 5 cm depth increase for the HD_ROI. The ART plan results show that the dose changes in the HD_ROI was greater than the LW_ROI’s.

Conclusion: Phantom thicknesses change can lead to a serious dose increase or decrease in the HD_ROI and LW_ROI’s.

Schlüsselwörter

  • phantom thickness
  • adaptive radiotherapy
  • dissymmetric analysis
  • helical tomotherapy
access type Uneingeschränkter Zugang

A simple multi-feature based stereoscopic medical image retrieval system

Online veröffentlicht: 18 Jun 2019
Seitenbereich: 127 - 130

Zusammenfassung

Abstract

This paper describes a method of retrieving stereoscopic medical images from the database that consists of feature extraction, similarity measure, and re-ranking of retrieved images. This method retrieves similar images of the query image from the database and re-ranks them according to the disparity map. The performance is evaluated using the metrics namely average retrieval precision (APR) and average retrieval rate (ARR). According to the performance outcomes, the multi-feature based image retrieval using Mahalanobis distance measure has produced better result compared to other distance measures namely Euclidean, Minkowski, the sum of absolute difference (SAD) and the sum of squared absolute difference (SSAD). Therefore, the stereo image retrieval systems presented has high potential in biomedical image storage and retrieval systems.

Schlüsselwörter

  • stereoscopic image retrieval
  • feature extraction
  • similarity measure
  • disparity map
  • average retrieval precision
  • average retrieval rate
access type Uneingeschränkter Zugang

Enhanced CAE system for detection of exudates and diagnosis of diabetic retinopathy stages in fundus retinal images using soft computing techniques

Online veröffentlicht: 18 Jun 2019
Seitenbereich: 131 - 139

Zusammenfassung

Abstract

Diabetic Retinopathy (DR) is one of the leading causes of visual impairment. Diabetic Retinopathy is the most recent technique of identifying the intensity of acid secretion in the eye for diabetic patients. The identification of DR is performed by visual analysis of retinal images for exudates (fat deposits) and the main patterns are traced by ophthalmologists. This paper proposes a fully automated Computer Assisted Evaluation (CAE) system which comprises of a set of algorithms for exudates detection and to classify the different stages of Diabetics Retinopathy, which are identified as either normal or mild or moderate or severe. Experimental validation is performed on a real fundus retinal image database. The segmentation of exudates is achieved using fuzzy C-means clustering and entropy filtering. An optimal set obtained from the statistical textural features (GLCM and GLHM) is extracted from the segmented exudates for classifying the different stages of Diabetics Retinopathy. The different stages of Diabetic Retinopathy are classified using three classifiers such as Back Propagation Neural Network (BPN), Probabilistic Neural Network (PNN) and Support Vector Machine (SVM). The experimental results show that the SVM classifiers outperformed other classifiers for the examined fundus retinal image dataset. The results obtained confirm that with new a set of texture features, the proposed methodology provides better performance when compared to the other methods available in the literature. These results suggest that our proposed method in this paper can be useful as a diagnostic aid system for Diabetic Retinopathy.

Schlüsselwörter

  • diabetic retinopathy
  • fundus retinal images
  • exudates
  • fuzzy C-means
  • entropy filtering
  • disease classification
10 Artikel
access type Uneingeschränkter Zugang

A literature review on multimodality molecular imaging nanoprobes for cancer detection

Online veröffentlicht: 18 Jun 2019
Seitenbereich: 57 - 68

Zusammenfassung

Abstract

Molecular imaging techniques using nanoparticles have significant potential to be widely used for the detection of various types of cancers. Nowadays, there has been an increased focus on developing novel nanoprobes as molecular imaging contrast enhancement agents in nanobiomedicine. The purpose of this review article is to summarize the use of a variety of nanoprobes and their current achievements in accurate cancer imaging and effective treatment. Nanoprobes are rapidly becoming potential tools for cancer diagnosis by using novel molecular imaging modalities such as Ultrasound (US) imaging, Computerized Tomography (CT), Single Photon Emission Tomography (SPECT) and Positron Emission Tomography (PET), Magnetic Resonance Imaging (MRI), and Optical Imaging. These imaging modalities may facilitate earlier and more accurate diagnosis and staging the most of cancers.

Schlüsselwörter

  • molecular imaging
  • nanoprobes
  • cancer
  • nanobiomedicine
access type Uneingeschränkter Zugang

Study the Anti-MUC1 antibody-based iron oxide nanoparticles on three-dimension spheroid and breast cancer (MCF-7) cell imaging

Online veröffentlicht: 18 Jun 2019
Seitenbereich: 69 - 77

Zusammenfassung

Abstract

Non-invasive methods for breast cancer detection in early stages may help to increase the survival rate of patients. This study aimed to evaluate the application of Anti-MUC1 antibody-based iron oxide nanoparticle (SPIONs-C595) which was assessed in vivo as a molecular imaging probe for breast cancer (MCF-7) detection using MRI. Nine groups of female NRC NU/Nu mice (each group of 3), 6 to 8 weeks old were used and MCF-7 cells were injected subcutaneously into both flanks of nude mice. After two weeks the mice received an intravenous injection of different concentrations of SPIONs-C595. The uptake ability of SPIONs-C595 on three-dimension (3D) macrostructure is exploited a modified hanging drop method using Prussian blue for MCF-7 cells. The iron content was measured in liver, kidney, spleen, and tumor. The MR imaging features and biodistribution of nanoprobe was also investigated. The MR images obtained from digested tumor after nanoprobe administration in different time-period revealed that enhancement of T1 and T2 relaxation time. Moreover, the storage stability test was shown great application and no sedimentation of nanoparticles within two months storage at 4°C. Additionally, great validation of SPIONs-C595 on the 3D spheroid of MCF-7 was observed. The biodistribution analysis showed that iron content of the spleen was more than the other studied organs. These results highlighted the feasibility of an in-vivo model for detection of breast cancer MUC1 expression. Current researches are ongoing to further enhancement of relaxation times for classification of MUC1 status using clinical specimens.

Schlüsselwörter

  • SPIONs
  • MR imaging
  • MCF-7 cells
  • C595 monoclonal antibody
access type Uneingeschränkter Zugang

Bismuth-based nanoparticles as radiosensitizer in low and high dose rate brachytherapy

Online veröffentlicht: 18 Jun 2019
Seitenbereich: 79 - 85

Zusammenfassung

Abstract

Background: Recently bismuth-based nanoparticles have attracted increasing attention as a dose amplification agent in radiation therapy due to high atomic number, high photoelectric absorption, low cost, and low toxicity.

Objectives: This study aims to calculate physical aspects of dose enhancement of bismuth-based nanoparticles in the presence of brachytherapy source by Monte Carlo simulation and an analytical method for low mono-energy. Materials and methods: After simulation and validation brachytherapy sources (Iodine-125 and Ytterbium-169) by Monte Carlo code, bismuth-based nanoparticles (bismuth, bismuth oxide, bismuth sulfide, and bismuth ferrite) were modeled in the sizes of 50 nm and 100 nm for two concentrations of 10 and 20 mg/ml. Dose enhancement factors for the bismuth-based nanoparticles were measured at both brachytherapy sources. Furthermore, the dose amplification was calculated with an analytic method at 30 keV mono-energy.

Results: Dose enhancement factor was greatest with pure bismuth nanoparticles, followed by bismuth oxide, bismuth sulfide and bismuth ferrite for both radiation source and simulation methods. The dose amplification for the bismuth-based nanoparticles increased with increasing size and concentration of nanoparticles.

Conclusion: The physical aspect dose enhancement of the nanoparticles was shown by Monte Carlo and analytic method. The results have proved bismuth-based nanoparticles deserve further study as a radiosensitizer.

Schlüsselwörter

  • bismuth-based nanoparticles
  • brachytherapy source
  • radiosensitizer
  • Monte Carlo simulation
  • dose enhancement
access type Uneingeschränkter Zugang

A Monte Carlo study on the radio-sensitization effect of gold nanoparticles in brachytherapy of prostate by 103Pd seeds

Online veröffentlicht: 18 Jun 2019
Seitenbereich: 87 - 92

Zusammenfassung

Abstract

103Pd seed is being used for prostate brachytherapy. Additionally, the dose enhancement effect of gold nanoparticles (GNP) has been reported in previous studies. The aim of this study was to characterize the dosimetric effect of gold nanoparticles in brachytherapy with a 103Pd source. Two brachytherapy seeds including 103 Pd source was simulated using MCNPX Monte Carlo code. The seeds’ models were validated by comparing the MC with reported results. Then, GNPs (10 nm in diameter) with a concentration of 7mg Au/g were simulated uniformly inside the prostate of a humanoid computational phantom. Additionally, the dose enhancement factor (DEF) of nanoparticles was calculated for both modeled brachytherapy seeds. A good agreement was found between the MC calculated and the reported dosimetric parameters. For both seeds, an average DEF of 23% was obtained in tumor volume for prostate brachytherapy. The application of GNPs in conjunction with 103Pd seed in brachytherapy can enhance the delivered dose to the tumor and consequently leads to better treatment outcome.

Schlüsselwörter

  • Pd
  • prostate cancer
  • brachytherapy
  • Monte Carlo
  • gold nanoparticle
access type Uneingeschränkter Zugang

A GATE Monte Carlo model for a newly developed small animal PET scanner: the IRI-microPET

Online veröffentlicht: 18 Jun 2019
Seitenbereich: 93 - 100

Zusammenfassung

Abstract

Monte Carlo simulation is widely used in emission tomography, in order to assess image reconstruction algorithms and correction techniques, for system optimization, and study the parameters affecting the system performance. In the current study, the performance of the IRI-microPET system was simulated using the GATE Monte Carlo code and a number of performance parameters, including spatial resolution, scatter fraction, sensitivity, RMS contrast, and signal-to-noise ratio, evaluated and compared to the corresponding measured values. The results showed an excellent agreement between simulated and measured data: The experimental and simulated spatial resolutions (radial) for 18F in the center of the AFOV were 1.81 mm and 1.65 mm, respectively. The difference between the experimental and simulated sensitivities of the system was <7%. Simulated and experimental scatter fractions differed less than 9% for the mouse phantom in different timing windows. The validation study of the image quality indicated a good agreement in RMS contrast and signal-to-noise ratio. Also, system performance was compared with the two available commercial scanners which were simulated using GATE code. In conclusion, the assessment of the Monte Carlo modeling of the IRI-microPET system reveals that the GATE code is a flexible and accurate tool for describing the response of an animal PET system.

Schlüsselwörter

  • GATE
  • Monte Carlo
  • simulation
  • IRI-microPET
  • performance
access type Uneingeschränkter Zugang

The effect of SSD, Field size, Energy and Detector type for Relative Output Factor measurement in small photon beams as compared with Monte Carlo simulation

Online veröffentlicht: 18 Jun 2019
Seitenbereich: 101 - 110

Zusammenfassung

Abstract

Introduction: Small fields photon dosimetry is associated with many problems. Using the right detector for measurement plays a fundamental role. This study investigated the measurement of relative output for small photon fields with different detectors. It was investigated for three-photon beam energies at SSDs of 90, 95, 100 and 110 cm. As a benchmark, the Monte Carlo simulation was done to calculate the relative output of these small photon beams for the dose in water.

Materials and Methods: 6, 10 and 15 MV beams were delivered from a Synergy LINAC equipped with an Agility 160 multileaf collimator (MLC). A CC01 ion chamber, EFD-3G diode, PTW60019 microdiamond, EBT2 radiochromic film, and EDR2 radiographic film were used to measure the relative output of the linac. Measurements were taken in water for the CC01 ion chamber, EFD-3G diode, and the PTW60019. Films were measured in water equivalent RW3 phantom slabs. Measurements were made for 1 × 1, 2 × 2, 3 × 3, 4 × 4, 5 × 5 and a reference field of 10 × 10 cm2. Field sizes were defined at 100cm SSD. Relative output factors were also compared with Monte Carlo (MC) simulation of the LINAC and a water phantom model. The influence of voxel size was also investigated for relative output measurement. Results and Discussion: The relative output factor (ROF) increased with energy for all fields large enough to have lateral electronic equilibrium (LEE). This relation broke down as the field sizes decreased due to the onset of lateral electronic disequilibrium (LED). The high-density detector, PTW60019 gave the highest ROF for the different energies, with the less dense CC01 giving the lowest ROFs.

Conclusion: These are results compared to MC simulation, higher density detectors give higher ROF values. Relative to water, the ROF measured with the air-chamber remained virtually unchanged. The ROFs, as measured in this study showed little variation due to increased SSDs. The effect of voxel size for the Monte Carlo calculations in water does not lead to significant ROF variation over the small fields studied.

Schlüsselwörter

  • small-field dosimetry
  • relative output factor
  • electronic equilibrium
  • Monte Carlo
access type Uneingeschränkter Zugang

Feasibility study of conformal forward planned simultaneous integrated boost technique comparable to IMRT and VMAT in pelvic irradiation for locally advanced cervical cancer

Online veröffentlicht: 18 Jun 2019
Seitenbereich: 111 - 119

Zusammenfassung

Abstract

Aim: To check the feasibility of simultaneous integrated boost (SIB) using a forward planned field in field (FIF) conformal technique for the treatment of carcinoma of the cervix IIIB and compare it dosimetrically with other advanced inverse planning techniques.

Methods: In our study 33 patients of carcinoma of the cervix IIIB were planned for SIB using conformal FIF technique and they were compared with retrospectively planned IMRT and VMAT techniques. SIB using conformal FIF was planned by two different methods.

Results: The results of our study indicate that forward planned Conformal SIB techniques are comparable with inverse planned techniques dosimetrically, in terms of conformity Index, Homogeneity Index, Maximum dose, etc. The ability of FIF SIB plans to produce dose contrast in differential dose accumulation was compared and analyzed and the results were encouraging. To treat an advanced/bulky disease like Carcinoma of the Cervix IIIB in centers with large patient load, utilizing advanced techniques such as IMRT and VMAT is both technically and practically difficult. Despite VMAT’s shorter delivery time, the procedures involved are time-consuming.

Conclusion: Hence forward planned SIB techniques may be used to achieve similar dosimetric effects of IMRT and VMAT techniques without much compromise in plan quality and patient throughput for treating bulky carcinoma of the cervix IIIB cases. However, the clinical results need to be carefully compared and evaluated and reported.

Schlüsselwörter

  • forward planning
  • SIB
  • field in field
  • inverse planning
  • biological evaluation
  • carcinoma of the cervix
access type Uneingeschränkter Zugang

Effect of Changing Phantom Thickness on Helical Radiotherapy Plan: Dosimetric Analysis

Online veröffentlicht: 18 Jun 2019
Seitenbereich: 121 - 126

Zusammenfassung

Abstract

Purpose: The aim of this study is to investigate the effect of changing phantom thickness on high dose region of interest (HD_ROI) and low dose ROI’s (LW_ROI’s) doses during helical radiotherapy (RT) by utilizing Adaptive RT (ART) technique.

Materials and Methods: The cylindrical phantom (CP) is wrapped with different thickness boluses and scanned in the kilovoltage computed tomography (KVCT). HD_ROI and LW_ROI’s were created in contouring system and nine same plans (1.8 Gy/Fr) were made with images of different thicknesses CP. The point dose measurements were performed using ionization chamber in Helical Tomotherapy (HT) treatment machine. For detecting thickness reduction effect, CP was irradiated using bolus-designed plans and it was irradiated using without bolus plan. The opposite of this scenario was applied to determine the thickness increase. KVCT and megavoltage CT (MVCT) images were used for dose comparison. The HT Planned Adaptive Software was used to see the differences in the planning and verification doses at dose volume histograms (DVH).

Results: Point dose measurements showed a 4.480% dose increase in 0.5 cm depth reduction for HD_ROI. These differences reached 8.508% in 2 cm depth and 15,279% in 5 cm depth. At the same time, a dose reduction of 0.665% was determined for a 0.5cm depth increase, a dose reduction of 1.771% was determined for a 2 cm depth increase, a dose reduction of 5.202% was determined for a 5 cm depth increase for the HD_ROI. The ART plan results show that the dose changes in the HD_ROI was greater than the LW_ROI’s.

Conclusion: Phantom thicknesses change can lead to a serious dose increase or decrease in the HD_ROI and LW_ROI’s.

Schlüsselwörter

  • phantom thickness
  • adaptive radiotherapy
  • dissymmetric analysis
  • helical tomotherapy
access type Uneingeschränkter Zugang

A simple multi-feature based stereoscopic medical image retrieval system

Online veröffentlicht: 18 Jun 2019
Seitenbereich: 127 - 130

Zusammenfassung

Abstract

This paper describes a method of retrieving stereoscopic medical images from the database that consists of feature extraction, similarity measure, and re-ranking of retrieved images. This method retrieves similar images of the query image from the database and re-ranks them according to the disparity map. The performance is evaluated using the metrics namely average retrieval precision (APR) and average retrieval rate (ARR). According to the performance outcomes, the multi-feature based image retrieval using Mahalanobis distance measure has produced better result compared to other distance measures namely Euclidean, Minkowski, the sum of absolute difference (SAD) and the sum of squared absolute difference (SSAD). Therefore, the stereo image retrieval systems presented has high potential in biomedical image storage and retrieval systems.

Schlüsselwörter

  • stereoscopic image retrieval
  • feature extraction
  • similarity measure
  • disparity map
  • average retrieval precision
  • average retrieval rate
access type Uneingeschränkter Zugang

Enhanced CAE system for detection of exudates and diagnosis of diabetic retinopathy stages in fundus retinal images using soft computing techniques

Online veröffentlicht: 18 Jun 2019
Seitenbereich: 131 - 139

Zusammenfassung

Abstract

Diabetic Retinopathy (DR) is one of the leading causes of visual impairment. Diabetic Retinopathy is the most recent technique of identifying the intensity of acid secretion in the eye for diabetic patients. The identification of DR is performed by visual analysis of retinal images for exudates (fat deposits) and the main patterns are traced by ophthalmologists. This paper proposes a fully automated Computer Assisted Evaluation (CAE) system which comprises of a set of algorithms for exudates detection and to classify the different stages of Diabetics Retinopathy, which are identified as either normal or mild or moderate or severe. Experimental validation is performed on a real fundus retinal image database. The segmentation of exudates is achieved using fuzzy C-means clustering and entropy filtering. An optimal set obtained from the statistical textural features (GLCM and GLHM) is extracted from the segmented exudates for classifying the different stages of Diabetics Retinopathy. The different stages of Diabetic Retinopathy are classified using three classifiers such as Back Propagation Neural Network (BPN), Probabilistic Neural Network (PNN) and Support Vector Machine (SVM). The experimental results show that the SVM classifiers outperformed other classifiers for the examined fundus retinal image dataset. The results obtained confirm that with new a set of texture features, the proposed methodology provides better performance when compared to the other methods available in the literature. These results suggest that our proposed method in this paper can be useful as a diagnostic aid system for Diabetic Retinopathy.

Schlüsselwörter

  • diabetic retinopathy
  • fundus retinal images
  • exudates
  • fuzzy C-means
  • entropy filtering
  • disease classification

Planen Sie Ihre Fernkonferenz mit Scienceendo