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The Monte Carlo method and parallel estimation in the drawing up of radiosurgery treatment plans

The Monte Carlo method and parallel estimation in the drawing up of radiosurgery treatment plans
The Monte Carlo method and parallel estimation in the drawing up of radiosurgery treatment plans
Servizio di Fisica Sanitaria, Azienda Ospedaliera S. Giovanni Battista, Molinette, Torino. PURPOSE: We investigated the practical application of a calculation algorithm based on the Monte Carlo method to stereotactic radiosurgery treatment planning. In radiosurgery, high dose gradients and the lack of electronic disequilibrium make high resolution matrices and high computing power and speed necessary to obtain accurate dose distribution. To date, the main obstacle to the wider-spread use of the Monte Carlo method has been the huge computing time necessary to obtain a dose distribution on current hardware. MATERIAL AND METHODS: In this project, developed within the ESPRIT program, funded by the European Union, a Parsytec CC (Cognitive Computing) computer was used with 9 processors (Power PC 604, 133 Mhz, RAM 64 Mb) with IBM AIX/EPX OS and availability for Fortran parallel codes compilation, connected to a PC for data input, results rendering, and dose distribution calculation with a conventional algorithm for comparison with the Monte Carlo code (an EGS4 user code). The module named Rapt Region Extractor performs data compression with an octree method without decreasing resolution, for RAM and computing time requirements to remain acceptable. A model of the 6 MV photon beam from Clinac 2100C Varian linear accelerator was devised, based on incident photon energy spectrum and, for each collimator dimension, on bidimensional dose distribution orthogonal to beam direction measured at SSd = SAD = 100 cm. RESULTS: Parallelization was carried out on event numbers, allowing a simulation speed to number of processor ratio close to unity. A new random number generator was used, capable of correctly running on the parallel architecture. The simulation procedure includes: 1) CT acquisition in DICOM 3.0 format, Analyze or with scanner; 2) Target delineation, treatment arc definition. 3) Dose calculation, with both conventional and Monte Carlo methods. 4) Dose distribution rendering on every transverse, sagittal or coronal planes overlapped in color wash on anatomical representation. Comparison between conventional and Monte Carlo algorithms were carried out on an anthropomorphic phantom and 10 real patients, with 2.5 mm anatomical resolution and standard deviation never exceeding 2%. A simulation with 10,000,000 events and 1% maximum variance can be run in 43'. When PTV is an homogeneous areas the differences between the two methods are around 5%, while when PTV is localized in dishomogeneous areas discrepancies reach 20% in the bone. CONCLUSIONS: In conclusion, the feasibility of direct simulation with the Monte Carlo method in radiosurgery has been demonstrated within time and hardware costs compatible with clinical practice.
647-655
Scielzo, G
d0a22ec4-ba48-4ddb-94c7-a48208e8e468
Grillo Ruggieri, F
81dbe516-d7f2-42af-a4d0-1532a883919d
Schwarz, M
94f72f3e-33a5-4622-a406-72e3ea735915
Rivolta, A
50569ed0-2f26-4fe5-8c94-b660100b95e2
Brunelli, B
bebfdb15-d35d-440c-ac3e-087bdfa1e0fb
Surridge, M
3bd360fa-1962-4992-bb16-12fc4dd7d9a9
Gill, A
98b611df-897b-4416-932b-e14f97309a83
Rietbrock, C
468e513e-d90c-4206-a210-099211fc4e52
Scielzo, G
d0a22ec4-ba48-4ddb-94c7-a48208e8e468
Grillo Ruggieri, F
81dbe516-d7f2-42af-a4d0-1532a883919d
Schwarz, M
94f72f3e-33a5-4622-a406-72e3ea735915
Rivolta, A
50569ed0-2f26-4fe5-8c94-b660100b95e2
Brunelli, B
bebfdb15-d35d-440c-ac3e-087bdfa1e0fb
Surridge, M
3bd360fa-1962-4992-bb16-12fc4dd7d9a9
Gill, A
98b611df-897b-4416-932b-e14f97309a83
Rietbrock, C
468e513e-d90c-4206-a210-099211fc4e52

Scielzo, G, Grillo Ruggieri, F, Schwarz, M, Rivolta, A, Brunelli, B, Surridge, M, Gill, A and Rietbrock, C (1998) The Monte Carlo method and parallel estimation in the drawing up of radiosurgery treatment plans. Radiol Med, Torino, Italia. pp. 647-655 .

Record type: Conference or Workshop Item (Other)

Abstract

Servizio di Fisica Sanitaria, Azienda Ospedaliera S. Giovanni Battista, Molinette, Torino. PURPOSE: We investigated the practical application of a calculation algorithm based on the Monte Carlo method to stereotactic radiosurgery treatment planning. In radiosurgery, high dose gradients and the lack of electronic disequilibrium make high resolution matrices and high computing power and speed necessary to obtain accurate dose distribution. To date, the main obstacle to the wider-spread use of the Monte Carlo method has been the huge computing time necessary to obtain a dose distribution on current hardware. MATERIAL AND METHODS: In this project, developed within the ESPRIT program, funded by the European Union, a Parsytec CC (Cognitive Computing) computer was used with 9 processors (Power PC 604, 133 Mhz, RAM 64 Mb) with IBM AIX/EPX OS and availability for Fortran parallel codes compilation, connected to a PC for data input, results rendering, and dose distribution calculation with a conventional algorithm for comparison with the Monte Carlo code (an EGS4 user code). The module named Rapt Region Extractor performs data compression with an octree method without decreasing resolution, for RAM and computing time requirements to remain acceptable. A model of the 6 MV photon beam from Clinac 2100C Varian linear accelerator was devised, based on incident photon energy spectrum and, for each collimator dimension, on bidimensional dose distribution orthogonal to beam direction measured at SSd = SAD = 100 cm. RESULTS: Parallelization was carried out on event numbers, allowing a simulation speed to number of processor ratio close to unity. A new random number generator was used, capable of correctly running on the parallel architecture. The simulation procedure includes: 1) CT acquisition in DICOM 3.0 format, Analyze or with scanner; 2) Target delineation, treatment arc definition. 3) Dose calculation, with both conventional and Monte Carlo methods. 4) Dose distribution rendering on every transverse, sagittal or coronal planes overlapped in color wash on anatomical representation. Comparison between conventional and Monte Carlo algorithms were carried out on an anthropomorphic phantom and 10 real patients, with 2.5 mm anatomical resolution and standard deviation never exceeding 2%. A simulation with 10,000,000 events and 1% maximum variance can be run in 43'. When PTV is an homogeneous areas the differences between the two methods are around 5%, while when PTV is localized in dishomogeneous areas discrepancies reach 20% in the bone. CONCLUSIONS: In conclusion, the feasibility of direct simulation with the Monte Carlo method in radiosurgery has been demonstrated within time and hardware costs compatible with clinical practice.

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More information

Published date: 1998
Additional Information: Published in Italian Event Dates: June 1998
Venue - Dates: Radiol Med, Torino, Italia, 1998-05-31
Organisations: Electronics & Computer Science, IT Innovation

Identifiers

Local EPrints ID: 257299
URI: http://eprints.soton.ac.uk/id/eprint/257299
PURE UUID: 05c4da22-3b4a-49d1-a126-63db12e40f92

Catalogue record

Date deposited: 21 Mar 2003
Last modified: 08 Jan 2022 14:42

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Contributors

Author: G Scielzo
Author: F Grillo Ruggieri
Author: M Schwarz
Author: A Rivolta
Author: B Brunelli
Author: M Surridge
Author: A Gill
Author: C Rietbrock

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