Monte Carlo techniques in radiation medicine (original) (raw)
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Physics in Medicine and Biology, 2012
Monte Carlo (MC) computational techniques are widely used for applications in radiation medicine and have traditionally covered the areas of radiation dosimetry, shielding, radiotherapy treatment planning, and radiological imaging. Moreover, they have contributed to the improvement and understanding of the link between physical parameters of radiation delivery and therapy success. Recently, MC methods are being integrated with other technologies used in radiation therapy, such as inverse optimization, deformable image registration, and machine learning techniques for outcomes studies, etc.
Monte Carlo codes for medical radiation physics
Monte Carlo simulation methods are widely used in medical radiation physics. Presently, there are many generalpurpose or dedicated Monte Carlo (MC) codes with applications in any field of medical physics (diagnostic radiology, radiotherapy, nuclear medicine, and health physics). However, this short review emphasizes codes used in ionizing radiation therapy (like EGSnrc/BEAMnrc, MCNP, GEANT4, FLUKA or PENELOPE). A final paragraph is dedicated to a special issue: Monte Carlo Treatment Planning (MCTP). Currently, MC dose calculation engines are implemented in commercial treatment planning software as it is believed that the Monte Carlo method can provide an accuracy within 2-3 %. Some original results obtained by our group in the field of Monte Carlo simulation for medical radiation physics are shortly presented in this work.
Evolution of Computational Techniques Implementing Monte Carlo in Radiotherapy
The concept of Monte Carlo has shown its impact on almost all segments of not just science but even in management and arts. Since its evolution in 1950's, it has grown surprisingly to assist every field. Monte Carlo based methods works through random number generation and uses several techniques for statistical tests of pseudo numbers. Most of the applications of Monte Carlo come under the generic application category; also it has assisted the radiation physics a lot, to make radiation oncology well equipped with techniques for resolving complicated results of treatment planning systems (TPS) and new techniques emerging in radiotherapy. At present various codes like BEAM, EGSnrc, FLUKA, MCNPX and GEANT4 are based on random numbers. The programming based on these codes solves the problems arising from machine simulation to dose distribution. Its contribution to radiological and medical physics has been substantial and cannot be underestimated; also Monte Carlo has its own added advantages in computational techniques, especially the Monte Carlo N particle transport code (MCNP) plays a significant role in simulation of complex geometries and calculation of radiation dose by simulating behavior of subatomic particles. It is now a day not an accessory but has turned out to be an essential prerequisite for radiation physicists, as it is universally accepted that Monte Carlo is required for better measurement of dose distribution for machines. It can be concluded that the development of Monte Carlo technique did not follow any incremental approach but it tends to be evolved one. The latest developments in the Monte Carlo have scientifically proved and validated numerous models of newly emerging modalities like TomoTherapy and others. Apart from this, it is as necessary to train scholars in this crucial field as ongoing developments in emerging trends of Monte Carlo Method.
2014
In this paper, the authors' review the applicability of the open-source GATE Monte Carlo simulation platform based on the GEANT4 toolkit for radiation therapy and dosimetry applications. The many applications of GATE for state-of-the-art radiotherapy simulations are described including external beam radiotherapy, brachytherapy, intraoperative radiotherapy, hadrontherapy, molecular radiotherapy, and in vivo dose monitoring. Investigations that have been performed using GEANT4 only are also mentioned to illustrate the potential of GATE. The very practical feature of GATE making it easy to model both a treatment and an imaging acquisition within the same framework is emphasized. The computational times associated with several applications are provided to illustrate the practical feasibility of the simulations using current computing facilities.
Medical Physics, 2014
In this paper, the authors' review the applicability of the open-source GATE Monte Carlo simulation platform based on the GEANT4 toolkit for radiation therapy and dosimetry applications. The many applications of GATE for state-of-the-art radiotherapy simulations are described including external beam radiotherapy, brachytherapy, intraoperative radiotherapy, hadrontherapy, molecular radiotherapy, and in vivo dose monitoring. Investigations that have been performed using GEANT4 only are also mentioned to illustrate the potential of GATE. The very practical feature of GATE making it easy to model both a treatment and an imaging acquisition within the same framework 064301-1 Med. Phys. 41 (6), June 2014 Sarrut et al.: GATE for dosimetry 064301-2
Fast Monte Carlo for radiation therapy: the PEREGRINE Project
1997
The purpose of the PEREGRINE program is to bring high-speed, high- accuracy, high-resolution Monte Carlo dose calculations to the desktop in the radiation therapy clinic. PEREGRINE is a three- dimensional Monte Carlo dose calculation system designed specifically for radiation therapy planning. It provides dose distributions from external beams of photons, electrons, neutrons, and protons as well as from brachytherapy sources. Each external radiation source particle passes through collimator jaws and beam modifiers such as blocks, compensators, and wedges that are used to customize the treatment to maximize the dose to the tumor. Absorbed dose is tallied in the patient or phantom as Monte Carlo simulation particles are followed through a Cartesian transport mesh that has been manually specified or determined from a CT scan of the patient. This paper describes PEREGRINE capabilities, results of benchmark comparisons, calculation times and performance, and the significance of Monte Car...
Monte Carlo in radiotherapy: experience in a distributed computational environment
Journal of Physics: Conference Series, 2007
New technologies in cancer radiotherapy need a more accurate computation of the dose delivered in the radiotherapeutical treatment plan, and it is important to integrate sophisticated mathematical models and advanced computing knowledge into the treatment planning (TP) process. We present some results about using Monte Carlo (MC) codes in dose calculation for treatment planning. A distributed computing resource located in the Technologies and Health Department of the Italian National Institute of Health (ISS) along with other computer facilities (CASPUR -Inter-University Consortium for the Application of Super-Computing for Universities and Research) has been used to perform a fully complete MC simulation to compute dose distribution on phantoms irradiated with a radiotherapy accelerator. Using BEAMnrc and GEANT4 MC based codes we calculated dose distributions on a plain water phantom and air/water phantom. Experimental and calculated dose values below ±2% (for depth between 5 mm and 130 mm) were in agreement both in PDD (Percentage Depth Dose) and transversal sections of the phantom. We consider these results a first step towards a system suitable for medical physics departments to simulate a complete treatment plan using remote computing facilities for MC simulations .
Monte Carlo simulations of dynamic radiotherapy treatments
2012
The effects of tumour motion during radiation therapy delivery have been widely investigated. Motion effects have become increasingly important with the introduction of dynamic radiotherapy delivery modalities such as enhanced dynamic wedges (EDWs) and intensity modulated radiation therapy (IMRT) where a dynamically collimated radiation beam is delivered to the moving target, resulting in dose blurring and interplay effects which are a consequence of the combined tumor and beam motion. Prior to this work, reported studies on the EDW based interplay effects have been restricted to the use of experimental methods for assessing single-field non-fractionated treatments. In this work, the interplay effects have been investigated for EDW treatments. Single and multiple field treatments have been studied using experimental and Monte Carlo (MC) methods. Initially this work experimentally studies interplay effects for single-field non-fractionated EDW treatments, using radiation dosimetry systems placed on a sinusoidaly moving platform. A number of wedge angles (60º, 45º and 15º), field sizes (20 × 20, 10 × 10 and 5 × 5 cm 2), amplitudes (10-40 mm in step of 10 mm) and periods (2 s, 3 s, 4.5 s and 6 s) of tumor motion are analysed (using gamma analysis) for parallel and perpendicular motions (where the tumor and jaw motions are either parallel or perpendicular to each other). For parallel motion it was found that both the amplitude and period of tumor motion affect the interplay, this becomes more prominent where the collimator tumor speeds become identical. For perpendicular motion the amplitude of tumor motion is the dominant factor where as varying the period of tumor motion has no observable effect on the dose distribution. The wedge angle results suggest that the use of a large wedge angle generates greater dose variation for both parallel and perpendicular motions. The use of small field size with a large tumor motion results in the loss of wedged dose distribution for both parallel and perpendicular motion. From these single vi
MONTE CARLO SIMULATION IN INTERNAL RADIOTHERAPY OF THYROID CANCER
Thyroid radiotherapy is a cancer therapy that is treated by giving radioactive I-131 in Thyroid gland. This cancer is at the ninth from ten of common malignant cancer. A man has higher risk to get Thyroid cancer than a woman has. This organ is lain near human neck. This research aim was to simulate particle track of radiation I-131 and determine an absorbed dose and effective dose in Thyroid and other organs around Thyroid such as Brain, Lung and Cervical vertebrae. The simulation and calculation used Monte Carlo method operated by MCNPX software. Geometry of Thyroid and other organs used ORNL MIRD phantom geometry. From the results, it shown that particle track of radiation was distributed at Thyroid while several particles radiated other organs. The absorbed dose in Thyroid and other organs increased every rising activity of I-131 used, but the absorbed dose in other organs was less than in Thyroid. Radiation effect for damage cancer in Thyroid was shown by an effective dose which it increased every rising activity of I-131 used and the maximum effective dose was at 200 mCi activity of I-131. Although the effective dose in Thyroid increased, the effective dose in other organs like Brain, Lung and Cervical vertebrae was still less than in Thyroid so that the use of I-131 each activity did not really influence other organs around Thyroid.