This study will help the pbc users understand the limitation of pbc during the treatment planning of real cancer treatment plans, especially when tumor is located beyond highdensity tissue such. The convolution is performed between polyenergetic pencil beams and the planar photon energy fluence distribution. In this thesis, a dose calculation method based on the superposition of monte carlo simulated pencil beam kernels was developed. Eclipses pencil beam algorithm, does not take into account secondary electron transport, but pinnacles collapsed cone convolution algorithm, or. Comparison of dose calculations between pencilbeam and monte.
Pbra, with its extensive use of multidimensional arrays, is a good candidate for parallel processing. Clinical comparison of pencil beam convolution and clarkson. This algorithm is based on a pencil beam ker nel convolution. A 3d pencilbeambased superposition algorithm for photon dose calculation in heterogeneous media. Pencil beam algorithms are unsuitable for proton dose.
Model based dose calculation algorithms in external. Pencil beam pb and monte carlo mc are among the avaliable algorithms. Pencil beam and collapsed cone algorithm calculations for. Clinical comparison of pencil beam convolution and.
It is often used in proton therapy, to reduce unnecessary radiation exposure to surrounding noncancerous cells. It is designed to meet the requirements of an algorithm for 3d treatment planning that is general enough to handle irregularly shaped radiation fields incident on a heterogeneous patient. Eclipses pencil beam algorithm, does not take into account secondary electron transport, but pinnacles collapsed cone convolution algorithm, or the monte carlo method, both of which that do. Treatment planning using the pbra 6 is advantageous in that beam data is easily commissioned and the accuracy of pbra dose calculations 7,8 is comparable to monte carlotype dose algorithms. Comparison of pencil beam, collapsed cone and monte. The points that failed to satisfy the gamma criteria of 2%2 mm under the pencil beam calculation algorithm left. The pencilbeam is divided into a depthdirected and a lateral component, which are separately scaled. It assumes that any collimated photon beam hitting incident on the patient is actually a conglomeration of lots of smaller, narrow pencil beams.
Pbc and aaa have often been described in literature 26,27. Carlo algorithm in radiotherapy treatment planning for 6. The concept of redefinition was first used for both fixed and arced electron beams by hogstrom. A fast finite size pencil beam algorithm for dose calculation using gpus introduction fast and accurate dose calculation is a primary requirement for online adaptive radiotherapy. A gpubased pencil beam algorithm for dose calculations in proton radiation therapy article pdf available in computer and information science 6144 september 2015 with 263 reads. The aaa dose calculation model consists of two components, the configuration algorithm and the actual dose calculation algorithm 8. Pencil beams model eclipse uses pencil beams extracted from measurements spb or from monte carlo calculation aaa heterogeneities handled via effective path length longitudinal aaa adds a scaling of the spread of the pencil based on density lateral aaa also have an extensive beam modelling analytical anisotropic algorithm. The sequential implementation of the pbra is in production use at the md anderson cancer center, university of texas. Kernel represents the spread of energy from the primary photon interaction site throughout the volume 9. Pencil beam scanning is the practice of steering a beam of radiation or charged particles across an object. Pdf a 3d pencilbeam based superposition algorithm for photon. The main purpose of this study is to investigate the accuracy of pencil beam convolution pbc algorithm when highdensity inhomogeneity is involved along the photon beam path.
A pencil beam algorithm for proton dose calculations. The following is a list of treatment planning systems tps. Pdf a 3d pencilbeambased superposition algorithm for. Nov 01, 2017 currently, most proton therapy centers in the united states use tpss that employ a simple analytic algorithm for dose calculations, commonly known as a pencil beam algorithm. Purpose fast energy switching is of fundamental importance to implement motion mitigation techniques in pencil beam scanning proton therapy. Also used in monte carlo method for photon transport. Limitation of pencil beam convolution pbc algorithm for photon dose calculations in inhomogeneous medium. A 3d pencil beam based superposition algorithm for photon dose calculation in heterogeneous media. Extrafocal radiation mainly from the primary collimation and the field flattening filter. Four different types of treatment cases were analyzed. Regarding photon beams, one of the most used calculation algorithms implemented in 3dcrt three. Research open access comparison of dose calculations. The anisotropic analytical algorithm aaa is a pencil beam superpositionconvolution algorithm for dose calculations,68 available in the eclipse treatment planning software from varian medical systems palo alto, ca, that has shown good accuracy overall and a great ability to handle small fields in inhomogeneous media. Modeling of beam customization devices in the pencil beam splitting algorithm for heavy charged particle radiotherapy.
It assumes that any collimated photon beam hitting incident on the patient is. Pdf a gpubased pencil beam algorithm for dose calculations. It 381 assumes that any beam incidenting the patient is actually a conglomeration of 382 lots of pencil beams, and the dose at any point of interest is given as the. The pencil beam algorithm and the broad beam version are both fully implemented into a treatment planning system. Evaluation of the anisotropic analytical algorithm aaa in. Pencil beam and collapsed cone algorithm calculations for a lungtype volume using ct and the omp treatment planning system methods measurements have been carried out in both phantom and a specifically designed phantom which simulated human lung volume. Pdf modeling of beam customization devices in the pencil. The concept of redefinition was first used for both fixed and arced electron beams by hogstrom e t a l. Pencil beam redefinition algorithm pbra calculates radiation dose distributions. The pencil beam is divided into a depthdirected and a lateral component, which are separately scaled. The pencil beam algorithm does not take the changes of lateral scattering effects into consideration. The dose calculation with inhomogeneity correction has greatly improved the accuracy of dose calculation, especially when lowden.
A single polyenergetic kernel is used to represent the pencil. Modeling of beam customization devices in the pencilbeam splitting algorithm for heavy charged particle radiotherapy. Comparison of dose calculation algorithms for treatment planning in external photon beam. There were two considerations for making this choice.
Intensity modulated irradiation of a thorax phantom. Ionizing radiation photons or xrays use pencil beam scanning to precisely target a tumor. We studied the transient magnetic field effects at psi gantry 2 in order to develop a correction strategy for this beam position misplacement. The aim of this study is the dosimetric verification and comparative analysis of two different treatment planning systems tps using collapsed cone convolution ccc and pencil beam pb algorithms for treatment sites of head and neck, chest wallsupraclavicular region, lung and prostate. Radiation treatment planning has pencil beam scanning as one of its modalities. This list is updated based on statistics done over the results of the irradiation of the lung phantom for the new tpsalgorithm. Research open access comparison of dose calculations between. Limitation of pencil beam convolution pbc algorithm for photon. For each case, the volume definition was based on a clinical. Several proton therapy centers have studied monte carlo algorithms, but monte carlobased treatment planning remains rarely used clinically in the united states. Dosimetric comparison of pencil beam and monte carlo. Currently most proton therapy centers in the united states use tpss that utilize a simple analytic algorithm for dose calculations, commonly known as a pencil beam algorithm. We have developed a pencil beam algorithm for proton dose calculations which takes accurate account of the effects of materials upstream of the patient and of the air gap between them and the patient.
Pencil beam and collapsed cone algorithm calculations for a. Department of physics, yeungnam university, gyeongsan. The points that failed to satisfy the gamma criteria of 2%2 mm under the pencilbeam calculation algorithm left. Tps and pencil beam convolution algorithm pbc and anisotropic analytical algorithm aaa in varian eclipse tps. The pencil beam algorithm is dose calculation technique. A practical method to evaluate and verify dose calculation. The extent of separation, if any, between these beammodifying devices and the patient is particularly critical in this respect. The analytical anisotropic algorithm, aaa, is a 3d pencil beam convolutionsuperposition algorithm and implemented in varians treatment planning system eclipse. In this thesis, a dose calculation method based on the superposition of monte carlo simulated pencilbeam kernels was developed. Pdf in this work, a novel threedimensional superposition algorithm for photon dose calculation is presented.
A pencil beam algorithm for proton dose calculations iopscience. Evaluation of a proton pencil beam algorithm for dose. The dose distribution of the plan calculated by the pencilbeam calculation algorithm is shown in upper right field, and the reconstructed dose distribution using the 3dvh software based on the measurements is shown in the lower. The convolutionsuperposition, finite pencil beam and monte carlo methods are model based dose calculation systems. Comparison of pencil beam, collapsed cone and montecarlo algorithm in radiotherapy treatment planning for 6 mv photon sung jin kim, dong ho kim, sung kyu kim. Pdf a 3d pencilbeam based superposition algorithm for.
The extent of separation, if any, between these beam modifying devices and the patient is particularly critical in this respect. The dose distribution of the plan calculated by the pencil beam calculation algorithm is shown in upper right field, and the reconstructed dose distribution using the 3dvh software based on the measurements is shown in the lower. We investigated clinical pencil beam scanning pbs dose differences between pb and mcbased treatment planning for lung cancer patients. Gpubased finitesize pencil beam algorithm with 3d density. Fast pencil beam dose calculation for proton therapy using a. The iplan rt treatment planning system incorporates not only a pbc algorithm, but also a more recent monte carlo calculation. View the article pdf and any associated supplements and figures for a period of 48. The purpose of this work is to study and quantify the differences in calculated dose computed with two algorithms available in treatment planning systems. Fast pencil beam dose calculation for proton therapy using. Limitation of pencil beam convolution pbc algorithm for. A pencil beam model for photon dose calculation ahnesjo. Our group previously developed a pencil beam algorithm for calculating dose from a scanned proton beam in water that produced excellent agreement with. Overestimation of dose in the lung by up to 14%, 14, 15 has been observed with simple analytic algorithms eg, pencil beam because they fail to properly account for lateral scatter and loss of electronic equilibrium.
The precision can be recovered by either increasing the beam off time after an energy change waiting until the magnetic field is fully settled or by actively correcting for the misplacement. Expected dose calculation errors of the pencil beam algorithm are suppressed, because the dose to the low density region lung is reduced by the use of a noncoplanar beam arrangement and by intensity. Evaluation of pencil beam convolution and anisotropic. Pencil beam dose calculation algorithm martin g carolan, phd chief physicist, illawarra cancer care centre 10 nov 2010 the pencil beam algorithm is dose calculation technique. Tesering dorje, limitation of pencil beam convolution pbc algorithm for photon dose calculations in inhomogeneous medium, journal of cancer treatment and research. To create an arc therapy plan, certain current general calculation algorithms such as pencilbeam calculation pbc are based on discretizing the continuous arc into multiple fields to simulate an arc. Our group previously developed a pencil beam algorithm for calculating dose from a scanned proton beam in water that produced excellent agreement with dose distributions simulated with monte carlo mc. Scholz c, nill s, oelfke u 2003a comparison of imrt optimization based on a pencil beam and a superposition algorithm. A predictive algorithm for spot position corrections after. Below we will give details on how the pencil beam is developed from measured beam data and monte carlo calculated kernels. Comparison of dose calculation algorithms for treatment. The second model in omp is a collapsedcone convolution approach.
External beam photon dose calculations thomas rockwell mackie professor. Evaluation of a proton pencil beam algorithm for dose calculations in heterogeneous media. Differential hardening of the beam by the field flattening filter. We have previously described an implementation of a pencil beam algorithm running on graphics processing units gpus intended specifically for online dose calculation.
Here we present an extension to the dose calculation engine employing a doublegaussian beam model to better account for the lowdose halo. Pdf calculation of a pencil beam kernel from measured photon. Dose calculation algorithms in 3dcrt and imrt aapm. The major advantage of the pencil beam scanning developed by iba will be the pliancy in dose distribution shapes in an optimum way in term of minimizing the total treatment time. Difference between pencil beam algorithm and collapsed cone convolution algorithm for higher energy. Comparison of dose calculations between pencilbeam and. A method for photon dose calculation in radio therapy planning using pencil beam energy deposition kernels is presented. We present here an implementation of a photon dose pencil beam algorithm ahnesjo et al. This study will help the pbc users understand the limitation of pbc during the treatment planning of real cancer treatment plans, especially when tumor is located beyond highdensity tissue such as bone. A fast finite size pencil beam algorithm for dose calculation.
This is a continuation of a previous work 4 where the aaa was evaluated for different phantom geometries by experimental measurements and compared to the eclipse pencil beam convolution algorithm. It is therefore very important to rely on development of a fast and accurate dose calculation algorithm. Currently, most proton therapy centers in the united states use tpss that employ a simple analytic algorithm for dose calculations, commonly known as a pencil beam algorithm. First we would like the algorithm to be as fast as possible. In the pencil beam convolution algorithm pbc of brainlab. Predictions of the algorithm and results from experiments performed in a large. A 3d pencilbeam based superposition algorithm for photon dose calculation in heterogeneous media article pdf available in physics in medicine and biology 5314. This algorithm compute the dose in the patient as the superposition of the total energy released per unit mass with an energy deposition kernel. A total of five breast and five lung cases were calculated using the pb, cc, and mc algorithms. The pencil beam algorithm and the broadbeam version are both fully implemented into a treatment planning system. Dose calcualtion algorithms in 3dcrt and imrt 20080727. What has to be accounted for in model based methods finite source size. Department of radiation oncology, eulji university hospital, daejeon.
Here monte carlo simulations are performed in addition to experimental measurements. Pdf usually, pencil beam kernels for photon beam calculations are obtained by. For this reason, pencil beam algorithms are no longer allowed on clinical trials for lung treatment with photon therapy. A predictive algorithm for spot position corrections after fast energy switching in proton pencil beam scanning. Calculating each energy separately with a spectrum and monoenergetic.
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