Limits...
First year experience with newly developed Leksell Gamma Knife Perfexion.

Bhatnagar JP, Novotny J, Niranjan A, Kondziolka D, Flickinger J, Lunsford D, Huq MS - J Med Phys (2009)

Bottom Line: Excellent agreement is also found between the dosimetric characteristics of LGK PFX and LGK 4C for the 4 and 8 mm collimators.The set up and treatment of patients on the LGK PFX is much more efficient since it is a fully automated system.The system also provides more options to generate plan with high dosimetric conformity.

View Article: PubMed Central - PubMed

Affiliation: Department of Radiation Oncology, Neurological Surgery, University of Pittsburgh Cancer Institute, Pittsburgh, USA.

ABSTRACT
A new model of Leksell Gamma Knife(R) (LGK), known as Perfexion (LGK PFX), was introduced by Elekta Instrument, AB, Sweden, in 2006. This model has a radically different design from the earlier models U, B, C and 4C. Dosimetric characteristics of LGK PFX, technical differences between LGK PFX and LGK 4C, experience gained with acceptance testing and commissioning of the LGK PFX, and comparison between LGK PFX and LGK 4C are presented in this study. Excellent agreement is found between the manufacturers recommended values of absorbed dose rate, relative output factors for 4 and 8 mm collimators, coincidence of mechanical and dosimetric isocenter, FWHM for beam profiles for various collimators and those reported in the present study. Excellent agreement is also found between the dosimetric characteristics of LGK PFX and LGK 4C for the 4 and 8 mm collimators. Examples of clinical cases treated with LGK PFX and impact of LGK PFX on workflow and dosimetric conformity of treatment planning is also given. The set up and treatment of patients on the LGK PFX is much more efficient since it is a fully automated system. The system also provides more options to generate plan with high dosimetric conformity.

No MeSH data available.


LGK PFX radiation unit and collimator system. A) Cross section of the LGK PFX radiation unit. B) Detailed view of sectors; each sector holds 24 60Co sources and can be moved independent of other sectors in desired position to define a collimator size or to block beams. C) Sector position which defines a 4 mm collimator. D) Sector position which defines a 8 mm collimator. E) Sector position which defines a 16 mm collimator. (With permission of Elekta Instrument AB, Stockholm, Sweden.)
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Figure 0001: LGK PFX radiation unit and collimator system. A) Cross section of the LGK PFX radiation unit. B) Detailed view of sectors; each sector holds 24 60Co sources and can be moved independent of other sectors in desired position to define a collimator size or to block beams. C) Sector position which defines a 4 mm collimator. D) Sector position which defines a 8 mm collimator. E) Sector position which defines a 16 mm collimator. (With permission of Elekta Instrument AB, Stockholm, Sweden.)

Mentions: For the LGK PFX system, the range of collimators (beam size) is changed from the previous gamma knife models. Only three collimator sizes of 4, 8 and 16 mm are now available. The 4 and 8 mm collimator sizes are kept the same as for the previous models, but the 14 and 18 mm collimator sizes of the previous models are replaced with a 16 mm collimator size. The 120 mm thick tungsten collimator ring is subdivided into eight identical regions, each region containing 72 collimators (24 collimators for 4 mm, 24 collimators for 8 mm, and 24 collimators for 16 mm). The beam size for each region is changed automatically by moving 24 sources over selected collimator set. A sector containing 24 sources can be moved into one of the five different positions: 1) sector moved to home position when the system is in a standby mode, 2) sector moved to 8 mm collimator size, 3) sector moved to 4 mm collimator size, 4) sector moved to 16 mm collimator size and 5) sector moved to off position which is the position between 4 mm and 8 mm collimators providing blocking of all 24 sources. The sector movement is performed by servo-controlled motors with linear scales located at the rear of the radiation unit. Detailed figure of the LGK PFX collimator system is given in Figure 1. Comparison of calculated profiles of LGK PFX and LGK 4C is given in Figure 2.


First year experience with newly developed Leksell Gamma Knife Perfexion.

Bhatnagar JP, Novotny J, Niranjan A, Kondziolka D, Flickinger J, Lunsford D, Huq MS - J Med Phys (2009)

LGK PFX radiation unit and collimator system. A) Cross section of the LGK PFX radiation unit. B) Detailed view of sectors; each sector holds 24 60Co sources and can be moved independent of other sectors in desired position to define a collimator size or to block beams. C) Sector position which defines a 4 mm collimator. D) Sector position which defines a 8 mm collimator. E) Sector position which defines a 16 mm collimator. (With permission of Elekta Instrument AB, Stockholm, Sweden.)
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2807679&req=5

Figure 0001: LGK PFX radiation unit and collimator system. A) Cross section of the LGK PFX radiation unit. B) Detailed view of sectors; each sector holds 24 60Co sources and can be moved independent of other sectors in desired position to define a collimator size or to block beams. C) Sector position which defines a 4 mm collimator. D) Sector position which defines a 8 mm collimator. E) Sector position which defines a 16 mm collimator. (With permission of Elekta Instrument AB, Stockholm, Sweden.)
Mentions: For the LGK PFX system, the range of collimators (beam size) is changed from the previous gamma knife models. Only three collimator sizes of 4, 8 and 16 mm are now available. The 4 and 8 mm collimator sizes are kept the same as for the previous models, but the 14 and 18 mm collimator sizes of the previous models are replaced with a 16 mm collimator size. The 120 mm thick tungsten collimator ring is subdivided into eight identical regions, each region containing 72 collimators (24 collimators for 4 mm, 24 collimators for 8 mm, and 24 collimators for 16 mm). The beam size for each region is changed automatically by moving 24 sources over selected collimator set. A sector containing 24 sources can be moved into one of the five different positions: 1) sector moved to home position when the system is in a standby mode, 2) sector moved to 8 mm collimator size, 3) sector moved to 4 mm collimator size, 4) sector moved to 16 mm collimator size and 5) sector moved to off position which is the position between 4 mm and 8 mm collimators providing blocking of all 24 sources. The sector movement is performed by servo-controlled motors with linear scales located at the rear of the radiation unit. Detailed figure of the LGK PFX collimator system is given in Figure 1. Comparison of calculated profiles of LGK PFX and LGK 4C is given in Figure 2.

Bottom Line: Excellent agreement is also found between the dosimetric characteristics of LGK PFX and LGK 4C for the 4 and 8 mm collimators.The set up and treatment of patients on the LGK PFX is much more efficient since it is a fully automated system.The system also provides more options to generate plan with high dosimetric conformity.

View Article: PubMed Central - PubMed

Affiliation: Department of Radiation Oncology, Neurological Surgery, University of Pittsburgh Cancer Institute, Pittsburgh, USA.

ABSTRACT
A new model of Leksell Gamma Knife(R) (LGK), known as Perfexion (LGK PFX), was introduced by Elekta Instrument, AB, Sweden, in 2006. This model has a radically different design from the earlier models U, B, C and 4C. Dosimetric characteristics of LGK PFX, technical differences between LGK PFX and LGK 4C, experience gained with acceptance testing and commissioning of the LGK PFX, and comparison between LGK PFX and LGK 4C are presented in this study. Excellent agreement is found between the manufacturers recommended values of absorbed dose rate, relative output factors for 4 and 8 mm collimators, coincidence of mechanical and dosimetric isocenter, FWHM for beam profiles for various collimators and those reported in the present study. Excellent agreement is also found between the dosimetric characteristics of LGK PFX and LGK 4C for the 4 and 8 mm collimators. Examples of clinical cases treated with LGK PFX and impact of LGK PFX on workflow and dosimetric conformity of treatment planning is also given. The set up and treatment of patients on the LGK PFX is much more efficient since it is a fully automated system. The system also provides more options to generate plan with high dosimetric conformity.

No MeSH data available.