scholarly journals Assessment of DLG Correction Factor in Mobius3D Commissioning Affected by Couch Top

2020 ◽  
Author(s):  
Min Cheol Han ◽  
Jihun Kim ◽  
Chae-Seon Hong ◽  
Kyung Hwan Chang ◽  
Su Chul Han ◽  
...  
Keyword(s):  
Carbon Fiber ◽  
Correction Factor ◽  
Measurement Data ◽  
Dose Calculation ◽  
Dose Calculations ◽  
Difference Function ◽  
Calculation System ◽  
Dosimetric Leaf Gap ◽  
Dose Difference ◽  
Automatic Dose

Abstract Purpose: This study assesses the dosimetric leaf gap (DLG) correction factor in Mobius3D commissioning affected by a couch top platform and calculates the optimal DLG value according to the point dose difference function. Methods: DLG optimizations were performed for 3 LINAC machines and a total of 30 patient VMAT plans (i.e., 10 plans per each LINAC). Point dose calculations were performed using an automatic dose calculation system in Mobius3D as well as Mobis3D calculation using an MVP-based QA plan with a carbon fiber couch top. Subsequently, the results were compared with measurement data. Results: The averaged point dose measured for the MVP with a couch top decreased by approximately 2% relative to that without the couch top. The average of the optimal DLG factors increased by 1.153 due to the couch top effect for a dose decrease of 2% at the measured point. Conclusions: Users should adjust the DLG correction factor using a specific phantom (including MVP) with a couch top. If the factor adjusted by using MVP automatic dose calculation system, the factor should be increased by approximately 1.153 per 2% dose difference considering user’s couch top effect.

Monte Carlo calculations of an Elekta Precise SL-25 photon beam model

2015 ◽  
pp. 1-12
Author(s):  
Fátima Padilla-Cabal ◽  
Mailyn Pérez-Liva ◽  
Elier Lara ◽  
Rodolfo Alfonso ◽  
Neivy Lopez-Pino
Keyword(s):  
Monte Carlo ◽  
Measurement Data ◽  
Dose Calculation ◽  
Photon Beam ◽  
Beam Model ◽  
Dose Calculations ◽  
Clinical Implementation ◽  
Dose Distributions ◽  
Major Barrier ◽  
Reconstruction Methods

AbstractBackgroundMonte Carlo (MC) simulations have been used extensively for benchmarking photon dose calculations in modern radiotherapy using linear accelerators (linacs). Moreover, a major barrier to widespread clinical implementation of MC dose calculation is the difficulty in characterising the radiation source using data reported from manufacturers.PurposeThis work aims to develop a generalised full MC histogram source model of an Elekta Precise SL-25 linac (electron exit window, target, flattening filter, monitor chambers and collimators) for 6 MV photon beams used in standard therapies. The inclusion of many different probability processes such as scatter, nuclear reactions, decay, capture cross-sections and more led to more realistic dose calculations in treatment planning and quality assurance.Materials and methodsTwo different codes, MCNPX 2·6 and EGSr-BEAM, were used for the calculation of particle transport, first in the geometry of the internal/external accelerator source, and then followed by tracking the transport and energy deposition in phantom-equivalent tissues. A full phase space file was scored directly above the upper multilayer collimator’s jaws to derive the beam characteristics such as planar fluence, angular distribution and energy spectrum. To check the quality of the generated photon beam, its depth dose curves and cross-beam profiles were calculated and compared with measured data.ResultsIn-field dose distributions calculated using the accelerator models were tuned to match measurement data with preliminary calculations performed using the accelerator information provided by the manufacturer. Field sizes of 3×3, 5×5, 10×10, 15×15 and 20×20 cm2were analysed. Local differences between calculated and measured curve doses beneath 2% were obtained for all the studied field sizes. Higher discrepancies were obtained in the air–water interface, where measurements of dose distributions with the ionisation chamber need to be shifted for the effective point of measurement.ConclusionThe agreements between MC-calculated and measured dose distributions were excellent for both codes, showing the strength and stability of the proposed model. Beam reconstruction methods as direct input to dose-calculation codes using the recorded histograms can be implemented for more accurate patient dose estimation.

scholarly journals Dosimetric feasibility of magnetic resonance (MR)-based dose calculation of prostate radiotherapy using multilevel threshold algorithm

2017 ◽  
Vol 16 (4) ◽  
pp. 415-422
Author(s):  
Turki Almatani ◽  
Richard P. Hugtenburg ◽  
Ryan D. Lewis ◽  
Susan E. Barley ◽  
Mark A. Edwards
Keyword(s):  
Magnetic Resonance ◽  
Assessment Tool ◽  
Intensity Modulated Radiation Therapy ◽  
Dose Calculation ◽  
Dose Calculations ◽  
Mr Images ◽  
Prostate Radiotherapy ◽  
Collapsed Cone ◽  
Dosimetric Assessment ◽  
Dose Difference

AbstractObjectiveThe development of magnetic resonance (MR) imaging systems has been extended for the entire radiotherapy process. However, MR images provide voxel values that are not directly related to electron densities, thus MR images cannot be used directly for dose calculation. The aim of this study is to investigate the feasibility of dose calculations to be performed on MR images and evaluate the necessity of re-planning.MethodsA prostate cancer patient was imaged using both MR and computed tomography (CT). The multilevel threshold (MLT) algorithm was used to categorise voxel values in the MR images into three segments (air, water and bone) with homogeneous Hounsfield units (HU). An intensity-modulated radiation therapy plan was generated from CT images of the patient. The plan was then copied to the segmented MR datasets and the doses were recalculated using pencil beam (PB) and collapsed cone (CC) algorithms and Monte Carlo (MC) modelling.Resultsγ Evaluation showed that the percentage of points in regions of interest with γ<1 (3%/3 mm) were more than 94% in the segmented MR. Compared with the planning CT plan, the segmented MR plan resulted in a dose difference of –0·3, 0·8 and –1·3% when using PB, CC and MC algorithms, respectively.ConclusionThe segmentation and conversion of MR images into HU data using the MLT algorithm, used in this feasibility study, can be used for dose calculation. This method can be used as a dosimetric assessment tool and can be easily implemented in the clinic.

SU-E-T-673: Development of Monte Carlo Dose Calculation System for Tumor-Tracking Irradiation with a Gimbaled X-Ray Head

2011 ◽  
Vol 38 (6Part21) ◽  
pp. 3644-3645 ◽  
Author(s):  
Y Ishihara ◽  
A Sawada ◽  
M Nakamura ◽  
N Mukumoto ◽  
S Kaneko ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Dose Calculation ◽  
X Ray ◽  
Tumor Tracking ◽  
Calculation System ◽  
Monte Carlo Dose Calculation

Evaluation of BrachyDose Monte Carlo code for HDR brachytherapy: dose comparison against Acuros®BV and TG-43 algorithms

2019 ◽  
Vol 19 (1) ◽  
pp. 76-83
Author(s):  
Ayse Dagli ◽  
Fatma Yurt ◽  
Gultekin Yegin
Keyword(s):  
Cervical Cancer ◽  
Monte Carlo ◽  
Heterogeneous Media ◽  
Dose Calculation ◽  
Extreme Case ◽  
Low Density ◽  
Hdr Brachytherapy ◽  
Dose Calculations ◽  
Dose Distributions ◽  
Water Phantom

AbstractAim:The aim of this study is to investigate the accuracy of dose distributions calculated by the BrachyDose Monte Carlo (MC) code in heterogeneous media for high-dose-rate (HDR) brachytherapy and to evaluate its usability in the clinical brachytherapy treatment planning systems.Materials and methods:For dose comparisons, three different dose calculation algorithms were used in this study. Namely, BrachyDose MC code, Eclipse TG-43 dose calculation tool and Acuros®BV model-based dose calculation algorithm (MBDCA). Dose distributions were obtained using any of the above codes in various scenarios including ‘homogenous water medium scenario’, an ‘extreme case heterogeneous media scenario’ and clinically important ‘a patient with a cervical cancer scenario’. In the ‘extreme case, heterogeneous media scenario’, geometry is a rare combination of unusual high-density and low-density materials and it is chosen to provide a test environment for the propagation of photons in the interface of two materials with different absorption and scattering properties. GammaMed 192Ir Model 12i Source is used as the HDR brachytherapy source in this study. Dose calculations were performed for the cases where there is either a single source or five sources planted into the phantom geometry in all homogenous water phantom and extreme case heterogeneous media scenarios. For the scenario a patient with a cervical cancer, dose calculations were performed in a voxelized rectilinear phantom, which is constructed from a series of computed tomography (CT) slices of a patient, which are obtained from a CT device.Results:In homogeneous water phantom scenario, we observed no statistically significant dose differences among the dose distributions calculated by any of the three algorithms at almost every point in the geometry. In the extreme case heterogeneous media scenario, the dose calculation engines Acuros®BV and BrachyDose are agreed well within statistics in every region of the geometry and even in the points close to the interfaces of low-density and high-density materials. On the other hand, the dose values calculated by these two codes are significantly different from those calculated by the TG-43 algorithm. In the ‘a patient with a cervical cancer scenario’, the calculated D2cc dose difference between Acuros®BV and BrachyDose codes is within 2% in the rectum and 11% for the bladder and sigmoid. There was no meaningful difference in the mean dose values between MBDCAs in the bone structures.Conclusions:In this study, the accurate dose calculation capabilities of the BrachyDose program in HDR brachytherapy were investigated on various scenarios and, as a MC dose calculation tool, its effectiveness in HDR brachytherapy was demonstrated by comparative dose analysis.

scholarly journals Development of Volumetric Independent Dose Calculation System for Verification of the Treatment Plan in Image-Guided Adaptive Brachytherapy

2020 ◽  
Vol 10 ◽  
Author(s):  
Sang-Won Kang ◽  
Jin-Beom Chung ◽  
Kyeong-Hyeon Kim ◽  
Ji-Yeon Park ◽  
Hae-Jin Park ◽  
...  
Keyword(s):  
Treatment Plan ◽  
Dose Calculation ◽  
Image Guided ◽  
Calculation System

scholarly journals MLC parameters from static fields to VMAT plans: an evaluation in a RT-dedicated MC environment (PRIMO)

2019 ◽  
Vol 14 (1) ◽  
Author(s):  
Lucia Paganini ◽  
Giacomo Reggiori ◽  
Antonella Stravato ◽  
Valentina Palumbo ◽  
Pietro Mancosu ◽  
...  
Keyword(s):  
Dose Calculation ◽  
Planning System ◽  
Treatment Planning System ◽  
Output Factor ◽  
Water Phantom ◽  
Graphical Environment ◽  
Clinical Complexity ◽  
Output Factors ◽  
Dosimetric Leaf Gap ◽  
Clinical Cases

Abstract Background PRIMO is a graphical environment based on PENELOPE Monte Carlo (MC) simulation of radiotherapy beams able to compute dose distribution in patients, from plans with different techniques. The dosimetric characteristics of an HD-120 MLC (Varian), simulated using PRIMO, were here compared with measurements, and also with Acuros calculations (in the Eclipse treatment planning system, Varian). Materials and methods A 10 MV FFF beam from a Varian EDGE linac equipped with the HD-120 MLC was used for this work. Initially, the linac head was simulated inside PRIMO, and validated against measurements in a water phantom. Then, a series of different MLC patterns were established to assess the MLC dosimetric characteristics. Those tests included: i) static fields: output factors from MLC shaped fields (2 × 2 to 10 × 10 cm2), alternate open and closed leaf pattern, MLC transmitted dose; ii) dynamic fields: dosimetric leaf gap (DLG) evaluated with sweeping gaps, tongue and groove (TG) effect assessed with profiles across alternate open and closed leaves moving across the field. The doses in the different tests were simulated in PRIMO and then compared with EBT3 film measurements in solid water phantom, as well as with Acuros calculations. Finally, MC in PRIMO and Acuros were compared in some clinical cases, summarizing the clinical complexity in view of a possible use of PRIMO as an independent dose calculation check. Results Static output factor MLC tests showed an agreement between MC calculated and measured OF of 0.5%. The dynamic tests presented DLG values of 0.033 ± 0.003 cm and 0.032 ± 0.006 cm for MC and measurements, respectively. Regarding the TG tests, a general agreement between the dose distributions of 1–2% was achieved, except for the extreme patterns (very small gaps/field sizes and high TG effect) were the agreement was about 4–5%. The analysis of the clinical cases, the Gamma agreement between MC in PRIMO and Acuros dose calculation in Eclipse was of 99.5 ± 0.2% for 3%/2 mm criteria of dose difference/distance to agreement. Conclusions MC simulations in the PRIMO environment were in agreement with measurements for the HD-120 MLC in a 10 MV FFF beam from a Varian EDGE linac. This result allowed to consistently compare clinical cases, showing the possible use of PRIMO as an independent dose calculation check tool.

Characterizing Woodiness Carbon Fiber Precursor by Fractal Geometry Approach in Different Curing Conditions

2013 ◽  
Vol 710 ◽  
pp. 122-126
Author(s):  
Zhi Gao Liu ◽  
Qiu Hui Zhang ◽  
Guang Jie Zhao ◽  
Lu Zhang
Keyword(s):  
Fractal Dimension ◽  
Carbon Fiber ◽  
Fractal Dimensions ◽  
Morphological Characters ◽  
Curing Conditions ◽  
Surface Fractal ◽  
Dimension Measurement ◽  
Microscopy Image ◽  
Calculation System ◽  
Carbon Fiber Precursor

For exploring the variation of the surface morphology of carbon fiber precursor which was obtained from different curing conditions,this paper used the fractal dimension measurement method to analyze morphological characters of carbon fiber precursor surface through the electronic scanning electron microscopy image recognition and computer fractal calculation system. The experimental results show:the surface fractal dimensions of carbon fiber precursor were between 2.480~2.622 by TPSAM method, and the surface fractal dimensions of carbon fiber precursor were between 2.555~2.633 by PCM method, both methods show that the carbon fiber precursor surface is smooth. And the CCM is 2.678~2.755, this method shows that the precursor surface is concave and convex. The fractal dimension value obtained by TPSAM method and PCM method is closer, while the CCM is different. But the trend is almost the same, which shows that using the fractal dimension method to desirable the surface structure of carbon fiber precursor is desirable.

scholarly journals An Update on the Chemistry, Pharmacology and Dose Calculations of Mepivacaine Hydrochloride for Podiatrists in the United Kingdom

2020 ◽  
Author(s):  
Ian Reilly ◽  
Nicola Burt ◽  
Rebecca Reilly ◽  
Ajay Swami
Keyword(s):  
Local Anaesthetic ◽  
Dose Calculation ◽  
Good Choice ◽  
Dose Calculations ◽  
Drug Of Choice ◽  
Anaesthetic Agents ◽  
The United Kingdom ◽  
Voltage Gated Sodium Channels ◽  
Blocking Voltage ◽  
The Uk

Local anaesthetic agents suppress action potentials in excitable tissues by blocking voltage-gated sodium channels. In doing so they inhibit the depolarisation of nociceptive nerve fibres and so prevent the transmission of pain impulses. UK legislation allows HCPC-registered Podiatrists with POM-A annotation access to six local anaesthetic drugs and two of these with the addition of adrenaline. The use of local anaesthetia has transformed the treatment of nail pathology by Podiatrists. In the UK, the drug of choice in podiatric practice is 3% mepivacaine hydrochloride: it is a good choice of drug for digital anaesthesia. This paper will review the chemistry, pharmacology and dose calculation of mepivacaine, and challenge some of the orthodoxy over the rigid calculation of maximum safe dosages.

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