Suggesting a new design for multileaf collimator leaves based on Monte Carlo simulation of two commercial systems

Hariri, Sanaz; Shahriari, M.

doi:10.1120/jacmp.v11i3.3101

Cited by 5 publications

(2 citation statements)

References 22 publications

(36 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…We consider the jaws are made of Tungsten (ρ W = 15 g.cm −3 ) (Kdzioka et al 2006, Hariri andShahriari 2010). A range cut of 1 cm is assigned to photons, electrons and positrons in the collimator region.…”

Section: Secondary Collimator Model and Dose Calculations Using Geant...mentioning

confidence: 99%

Validation of a virtual source model of medical linac for Monte Carlo dose calculation using multi-threaded Geant4

Aboulbanine

Khayati

2018

Phys. Med. Biol.

View full text Add to dashboard Cite

The use of phase space in medical linear accelerator Monte Carlo (MC) simulations significantly improves the execution time and leads to results comparable to those obtained from full calculations. The classical representation of phase space stores directly the information of millions of particles, producing bulky files. This paper presents a virtual source model (VSM) based on a reconstruction algorithm, taking as input a compressed file of roughly 800 kb derived from phase space data freely available in the International Atomic Energy Agency (IAEA) database. This VSM includes two main components; primary and scattered particle sources, with a specific reconstruction method developed for each. Energy spectra and other relevant variables were extracted from IAEA phase space and stored in the input description data file for both sources. The VSM was validated for three photon beams: Elekta Precise 6 MV/10 MV and a Varian TrueBeam 6 MV. Extensive calculations in water and comparisons between dose distributions of the VSM and IAEA phase space were performed to estimate the VSM precision. The Geant4 MC toolkit in multi-threaded mode (Geant4-[mt]) was used for fast dose calculations and optimized memory use. Four field configurations were chosen for dose calculation validation to test field size and symmetry effects, [Formula: see text] [Formula: see text], [Formula: see text] [Formula: see text], and [Formula: see text] [Formula: see text] for squared fields, and [Formula: see text] [Formula: see text] for an asymmetric rectangular field. Good agreement in terms of [Formula: see text] formalism, for 3%/3 mm and 2%/3 mm criteria, for each evaluated radiation field and photon beam was obtained within a computation time of 60 h on a single WorkStation for a 3 mm voxel matrix. Analyzing the VSM's precision in high dose gradient regions, using the distance to agreement concept (DTA), showed also satisfactory results. In all investigated cases, the mean DTA was less than 1 mm in build-up and penumbra regions. In regards to calculation efficiency, the event processing speed is six times faster using Geant4-[mt] compared to sequential Geant4, when running the same simulation code for both. The developed VSM for 6 MV/10 MV beams widely used, is a general concept easy to adapt in order to reconstruct comparable beam qualities for various linac configurations, facilitating its integration for MC treatment planning purposes.

show abstract

Section: Secondary Collimator Model and Dose Calculations Using Geant...mentioning

confidence: 99%

Validation of a virtual source model of medical linac for Monte Carlo dose calculation using multi-threaded Geant4

Aboulbanine

Khayati

2018

Phys. Med. Biol.

View full text Add to dashboard Cite

show abstract

“… a SCD = 35.1 cm, leaf height = 9 cm [ 14 ]. b SCD = 51.02 cm, leaf height = 5.65 cm [ 15 ]. Angle α l denotes the angle between line segment of piecewise leaf end curve and collimator rotation axis.…”

Section: Figurementioning

confidence: 99%

Lateral Penumbra Modelling Based Leaf End Shape Optimization for Multileaf Collimator in Radiotherapy

Zhou

Zhang

2016

Computational and Mathematical Methods in Medicine

View full text Add to dashboard Cite

Lateral penumbra of multileaf collimator plays an important role in radiotherapy treatment planning. Growing evidence has revealed that, for a single-focused multileaf collimator, lateral penumbra width is leaf position dependent and largely attributed to the leaf end shape. In our study, an analytical method for leaf end induced lateral penumbra modelling is formulated using Tangent Secant Theory. Compared with Monte Carlo simulation and ray tracing algorithm, our model serves well the purpose of cost-efficient penumbra evaluation. Leaf ends represented in parametric forms of circular arc, elliptical arc, Bézier curve, and B-spline are implemented. With biobjective function of penumbra mean and variance introduced, genetic algorithm is carried out for approximating the Pareto frontier. Results show that for circular arc leaf end objective function is convex and convergence to optimal solution is guaranteed using gradient based iterative method. It is found that optimal leaf end in the shape of Bézier curve achieves minimal standard deviation, while using B-spline minimum of penumbra mean is obtained. For treatment modalities in clinical application, optimized leaf ends are in close agreement with actual shapes. Taken together, the method that we propose can provide insight into leaf end shape design of multileaf collimator.

show abstract

Development and performance evaluation of a high‐speed multileaf collimator

Zhang

2016

J Applied Clin Med Phys

View full text Add to dashboard Cite

Multileaf collimator (MLC) tracking represents a promising technique for motion management in radiotherapy. However, the conflict between limited leaf speed/acceleration and the demand for tracking fast target motion is now a prominent issue. Conventional MLCs typically have a maximum leaf speed of 3–4 cm/s and a maximum leaf acceleration of 50–70 cm/s2, which are inadequate to track fast target motion. To cope with this problem, we have recently developed a high‐speed multileaf collimator (HS‐MLC) prototype, which employs linear motors instead of rotary motors to drive leaves. Consequently, it inherits various benefits of linear motors, including direct drive and high dynamics. The primary aim of this paper was to introduce the development and performance evaluation of the HS‐MLC. The evaluation includes Monte Carlo simulations of the basic dosimetric properties, camera‐based measurements of the mechanical properties and tracking experiments for 25 sets of patient‐measured motion data. The Monte Carlo simulation results show that the maximum leakage at 6MV is 1.29% and the average is 0.61%. The end‐to‐end leakage is 3.96% for 5 cm offset and is 1.75% for 10 cm offset. The penumbra for a standard 10 × 10 cm2 field ranges from 4.8 mm to 5.4 mm across the full range of leaf motion. The mechanical property measurements demonstrate that the maximum leaf speed is 40 cm/s, the maximum leaf acceleration is 1000 cm/s2, and the geometric accuracy can be kept within 0.5 mm. Regarding the tracking experiments for a wide range of motion patterns (fast breathing, irregular breathing, etc.), a root‐mean‐square error (RMSE) of less than 0.19 mm was achieved. In conclusion, the HS‐MLC is able to well track fast target motion that is beyond the capability of conventional MLCs due to its superior mechanical properties. The new MLC design provides a feasible solution to make high‐accuracy and high‐efficiency motion management possible.

show abstract

Suggesting a new design for multileaf collimator leaves based on Monte Carlo simulation of two commercial systems

Cited by 5 publications

References 22 publications

Validation of a virtual source model of medical linac for Monte Carlo dose calculation using multi-threaded Geant4

Validation of a virtual source model of medical linac for Monte Carlo dose calculation using multi-threaded Geant4

Lateral Penumbra Modelling Based Leaf End Shape Optimization for Multileaf Collimator in Radiotherapy

Development and performance evaluation of a high‐speed multileaf collimator

Contact Info

Product

Resources

About