Monte Carlo techniques in medical radiation physics. Phys Med Biol

Department of Radiation Physics, Karolinska Institute, Stockholm, Sweden.
Physics in Medicine and Biology (Impact Factor: 2.76). 08/1991; 36(7):861-920. DOI: 10.1088/0031-9155/36/7/001
Source: PubMed


The author's main purpose is to review the techniques and applications of the Monte Carlo method in medical radiation physics since Raeside's review article in 1976. Emphasis is given to applications where proton and/or electron transport in matter is simulated. Some practical aspects of Monte Carlo practice, mainly related to random numbers and other computational details, are discussed in connection with common computing facilities available in hospital environments. Basic aspects of electron and photon transport are reviewed, followed by the presentation of the Monte Carlo codes widely available in the public domain. Applications in different areas of medical radiation physics, such as nuclear medicine, diagnostic X-rays, radiotherapy physics (including dosimetry), and radiation protection, and also microdosimetry and electron microscopy, are presented. Actual and future trends in the field, like Inverse Monte Carlo methods, vectorization of codes and parallel processors calculations are also discussed.

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    • "The transport of neutral particles, such as photons, is performed by considering that the particle's " birth " is the result of the characterization of the source and the specification of relevant information , such as the energy of the primary beam, for example. The particle's history consists of the interactions it experiments within the medium through collisions and scatterings which affect its energy and direction of motion (Andreo, 1991; Raeside, 1976). The history ends when interactions such as pair production or photoelectric effect take place, or when a threshold energy for the Compton Effect is defined. "
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    ABSTRACT: a b s t r a c t In this work, the main components of Siemens ONCORÔ Expression linear accelerator have been modeled using the Monte Carlo code MCNPX. The model thus developed has been used in the validation of the 6 and 15 MV photon beams, applying the phase space technique. The Percentage Depth Dose (PDD), the profiles, and the photon spectrum of the 10 Â 10 cm 2 field have been calculated for both megavoltage beams. The higher emission probability in the low-energy portion of the photon spectrum has been determined for the 6 MV beam, in order to enhance the image of the Cone Beam Computed Tomography with megavoltage beam, using the Flat Panel portal. Results obtained for the Percentage Depth Dose have shown an agreement of better than 1% with the measured values in the regions beyond the build-up, for both beams. The profiles simulated at different depths have shown a good agreement with experimental values, below of the tolerances established. The photon spectrum calculated for the 10 Â 10 cm 2 field show that energies lower 250 keV tend to present a higher probability of emission, especially when the 6 MV beam is considered. This is probably due to the use of low density materials in the target of the linear accelerator.
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    • "kalantzis). calculations on the scale of nanometers and therefore singleinteraction algorithms are preferred [5]. Several theoretical models have been proposed for calculating the cross sections that are applicable to MC simulations of electron and proton tracking [9] [10] [11] [12] [13] [14] [15] [16]. "
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    ABSTRACT: For microdosimetric calculations event-by-event Monte Carlo (MC) methods are considered the most accurate. The main shortcoming of those methods is the extensive requirement for computational time. In this work we present an event-by-event MC code of low projectile energy electron and proton tracks for accelerated microdosimetric MC simulations on a graphic processing unit (GPU). Additionally, a hybrid implementation scheme was realized by employing OpenMP and CUDA in such a way that both GPU and multi-core CPU were utilized simultaneously. The two implementation schemes have been tested and compared with the sequential single threaded MC code on the CPU. Performance comparison was established on the speed-up for a set of benchmarking cases of electron and proton tracks. A maximum speedup of 67.2 was achieved for the GPU-based MC code, while a further improvement of the speedup up to 20% was achieved for the hybrid approach. The results indicate the capability of our CPU-GPU implementation for accelerated MC microdosimetric calculations of both electron and proton tracks without loss of accuracy.
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    • "They solve the radiation transport problem stochastically by simulating the tracks of a sufficiently large number of individual particles using the random number generated probability distribution governing the individual physical processes. They are therefore capable of accurately computing the radiation dose in media under almost all circumstances [19, 20]. However, the computation time required may still limit the use of MC methods for complex intensity modulated techniques in the clinical environment. "
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    ABSTRACT: Deterministic linear Boltzmann transport equation (D-LBTE) solvers have recently been developed, and one of the latest available software codes, Acuros XB, has been implemented in a commercial treatment planning system for radiotherapy photon beam dose calculation. One of the major limitations of most commercially available model-based algorithms for photon dose calculation is the ability to account for the effect of electron transport. This induces some errors in patient dose calculations, especially near heterogeneous interfaces between low and high density media such as tissue/lung interfaces. D-LBTE solvers have a high potential of producing accurate dose distributions in and near heterogeneous media in the human body. Extensive previous investigations have proved that D-LBTE solvers were able to produce comparable dose calculation accuracy as Monte Carlo methods with a reasonable speed good enough for clinical use. The current paper reviews the dosimetric evaluations of D-LBTE solvers for external beam photon radiotherapy. This content summarizes and discusses dosimetric validations for D-LBTE solvers in both homogeneous and heterogeneous media under different circumstances and also the clinical impact on various diseases due to the conversion of dose calculation from a conventional convolution/superposition algorithm to a recently released D-LBTE solver.
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