In some circumstances passive detecting methods are the only or preferable measuring approaches. For instance, defining particles׳ energy profile inside the objects being irradiated with heavy ions ...and measuring fluence of neutrons or heavy particles in space missions are the cases covered by these methods. In this paper the ability of polyallyl diglycol carbonate (PADC) track detector (commercially known as CR-39) for passive spectrometry of proton particles is studied. Furthermore, the effect of KOH and NaOH as commonly used chemical etching solutions on the response of the detector is investigated. The experiments were carried out with protons in the energy range of 0.94–2.5MeV generated by a Van de Graaff accelerator. Then, the exposed track dosimeters were etched in the two aforementioned etchants through similar procedure with the same normality of 6.25N and the same temperature of 85°C. Formation of the tracks was precisely investigated and the track diameters were recorded following every etching step for each solution using a multistage etching process. The results showed that the proposed method can be efficiently used for the spectrometry of protons over a wider dynamic range and with a reasonable accuracy. Moreover, NaOH and KOH outperformed each other over different regions of the proton energy range. The detection efficiency of both etchants was approximately 100%.
A new hadron-therapy facility implementing an active beam scanning technique has been developed at the Italian National Center of Oncological Hadron-therapy (CNAO). This paper presents the design and ...the characterization of the beam monitor detectors developed for the on-line monitoring and control of the dose delivered during a treatment at CNAO. The detectors are based on five parallel-plate transmission ionization chambers with either a single large electrode or electrodes segmented in 128 strips (strip chambers) and 32×32pixels (pixel chamber). The detectors are arranged in two independent boxes with an active area larger than 200×200mm2 and a total water equivalent thickness along the beam path of about 0.9mm. A custom front-end chip with 64 channels converts the integrated ionization channels without dead-time.
The detectors were tested at the clinical proton beam facility of the Paul Scherrer Institut (PSI) which implements a spot scanning technique, each spot being characterized by a predefined number of protons delivered with a pencil beam in a specified point of the irradiation field. The short-term instability was measured by delivering several identical spots in a time interval of few tenths of seconds and is found to be lower than 0.3%. The non-uniformity, measured by delivering sequences of spots in different points of the detector surface, results to be lower than 1% in the single electrode chambers and lower than 1.5% in the strip and pixel chambers, reducing to less than 0.5% and 1% in the restricted 100×100mm2 central area of the detector.
During the last decade, information system (IS) outsourcing has emerged as a major issue for organizations. As outsourcing decisions are often based on multicriteria approaches and group decisions, ...this paper proposes a structured methodology based on Fuzzy group decision making approach to evaluate and select the appropriate information system project (ISP) in an actual case. To achieve our purpose, we argue that seven criteria consisting of risk, management, economics, technology, resource, quality, and strategy and five ISPs should be considered for outsourcing decisions. Fuzzy analytic hierarchy process (fuzzy AHP) to find the priority and ranking of each ISP is considered. Using fuzzy theory for selecting the proper IS project can reduce ambiguities and uncertainties that are inherent in the selection procedure. A sensitivity analysis is performed to check the steadiness of the priority ranking and help decision makers to understand different scenarios that show alternative potential developments or different viewpoints concerning the relative importance of the criteria. Our proposed methodology can be applied by a cross-functional team of practitioners and IT managers to select the proper IS project. Also, the proposed approach can effectively consider complex and qualitative decision variables involved in the IS outsourcing decision-making problem. Finally, conclusion and potential issues for future research are presented. The main findings of this research have showed that the combination of AHP method and fuzzy concept to rank and prioritize of IS projects to outsource is a useful and practical tool to make traceable and reliable decision. According to results, a priority of overall score for the five candidates of IS projects reflects that project of "development of the supplier relationship management information system" performs the best, and project of "facilities management" performs the worst according to the experts' judgment in case study.
In hadron therapy one of the most advanced methods for beam delivery is the active scanning technique which uses fast scanning magnets to drive a narrow particle beam across the target. The Centro ...Nazionale di Adroterapia Oncologica (CNAO) will treat tumours with this technique. The CNAO scanning system includes two identical dipole magnets for horizontal and vertical beam deflection, each one connected to a fast power supply. The dose delivery system exploits a set of monitor chambers to measure the fluence and position of the beam and drives the beam during the treatment by controlling the sequence of currents set by the power supplies. A test of the dynamic performance of the scanning system has been performed using a Hall probe to measure the field inside the magnet and the results are presented in this paper.
Quasidiscrete scanning is a delivery strategy for proton and ion beam therapy in which the beam is turned off when a slice is finished and a new energy must be set but not during the scanning between ...consecutive spots. Different scanning paths lead to different dose distributions due to the contribution of the unintended transit dose between spots. In this work an algorithm to optimize the scanning path for quasidiscrete scanned beams is presented. The classical simulated annealing algorithm is used. It is a heuristic algorithm frequently used in combinatorial optimization problems, which allows us to obtain nearly optimal solutions in acceptable running times. A study focused on the best choice of operational parameters on which the algorithm performance depends is presented. The convergence properties of the algorithm have been further improved by using the next-neighbor algorithm to generate the starting paths. Scanning paths for two clinical treatments have been optimized. The optimized paths are found to be shorter than the back-and-forth, top-to-bottom (zigzag) paths generally provided by the treatment planning systems. The gamma method has been applied to quantify the improvement achieved on the dose distribution. Results show a reduction of the transit dose when the optimized paths are used. The benefit is clear especially when the fluence per spot is low, as in the case of repainting. The minimization of the transit dose can potentially allow the use of higher beam intensities, thus decreasing the treatment time. The algorithm implemented for this work can optimize efficiently the scanning path of quasidiscrete scanned particle beams. Optimized scanning paths decrease the transit dose and lead to better dose distributions.
Abstract A detector (MOPI) has been developed for the online monitoring of the beam at the Centro di AdroTerapia e Applicazioni Nucleari Avanzate (CATANA), where shallow tumours of the ocular region ...are treated with 62 MeV protons. At CATANA the beam is passively spread to match the tumour shape. The uniformity of the delivered dose depends on beam geometrical quantities which are checked before each treatment. However, beam instabilities might develop during the irradiation affecting the dose distribution. This paper reports on the use of the MOPI detector to measure the stability of the beam profile during the irradiation in the clinical practice. The results obtained in the treatment of 54 patients are also presented.
Purpose: The purpose of this report is to investigate the effects on the Relative Biological Effectiveness (RBE) due to nuclear fragmentation during irradiation with therapeutic carbon ion beams, by ...using biological model calculations. Method and Materials: In order to disentangle the biological effects of the mixed particle fields, we evaluated the RBE originated by primary carbon ions and by fragments together and separately. The radiobiological efficiency of charged particles is mainly characterized by their high local ionization density which can be directly correlated to the local density of DNA damage. We developed a code based on the Local Effect Model (LEM) for the calculation of the cell survival after irradiation with carbon ions. As input we use particle distributions sampled at different depths in a water volume, for different energies of the primary ions (between 150 and 400 MeV/u), generated by Monte Carlo simulations using the package GEANT4. The computational effort was performed using the distributed INFN (Istituto Nazionale di Fisica Nucleare) Grid computing resources. Results: For carbon ions, high RBE values were found in the high‐LET region (Bragg peak), as well as in the low‐dose region, the distal region after the Bragg peak, where the contribution to the RBE is mainly due to fragments. We show that the global biological effect can be well reconstructed by a weighted combination of the alpha and beta parameters of the Linear‐Quadratic Model (LQM) evaluated separately for primary ions and fragments. The analysis provided also an estimate of the RBE sensitivity to the uncertainties present in the experimental data of fragment yield. Conclusion: Our work estimated the impact of the fragments in hadrontherapy using carbon ion beams. Due to the high RBE values found, the resulting biological dose can be important in regions outside the irradiated target, in presence of organs at risk.
Radiation quantity values at all points of a known distance range of gamma radiation calibration fields were calculated using a mathematical method. The method is based on interpolation using ...Chi-square test on a set of experimental data at optional points of both collimated and un-collimated calibration set-ups by means of a reference instrument. In comparison with Monte Carlo calculations, the values that were calculated by this method differ by <1% for collimated and 2% for un-collimated calibration set-ups. Consequently, the radiation quantities at all points of gamma radiation calibration field set-ups can accurately be formulated and determined by this method. In addition, all points in the radiation fields can be regarded as test points.
Although ERP systems have lots of advantages for the organization, the ERP implementation is not straightforward and involves significant risks. Several studies have conducted to identify the ...critical success factors (CSFs) in the ERP implementation process, but most of them are lacking of systematic efforts to classify and evaluate CSFs. To achieve this aim, a structured methodology based on a fuzzy analytical hierarchy process is proposed to rank a set of critical success factors related to ERP implementation process. The proposed methodology has been implemented at a refrigerator manufacturer company in Iran. The results of this study show that "Managers and employees readiness to change", "Top management Support", "Business Process Reengineering", "Software and user interface development" and "Change management" are five top CSFs.
In this paper, a novel systematic method to obtain the most proper organizational safety strategies in a textile company in Iran by utilizing SWOT concept is presented. After finding the SWOT factors ...DEMATEL method is applied to find inter relations and casual diagram of factors for each four clusters separately. By considering the factor relationship structures, "SO, WO, ST and WT" strategies are obtained. In next step by group fuzzy AHP several criteria to find most proper strategies are weighted. Finally ELECTRE is utilized to find efficient group of strategies. One of the contributions of this research is to use DEMATEL to obtain importance of each factor in SWOT matrix and considering this importance to determine strategies.
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