Monte Carlo calculated output factors of a Leksell Gamma Knife unit

Cheung, Joel Y. C.; Yu, K.N.; Ho, Robert; Yu, Cheng

doi:10.1088/0031-9155/44/12/401

Cited by 37 publications

(28 citation statements)

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“…Different authors performed MC calculations of OFs for LGKP and previous models with results mostly consistent with vendor recommended values. [25][26][27][28] These simulations can be used as reference for the OFs calculation. However, actual and independent dosimetric validations are required to check the parameters as part of initial commissioning and routine quality assurance procedures.…”

Section: Discussionmentioning

confidence: 99%

Evaluation of a synthetic single‐crystal diamond detector for relative dosimetry on the Leksell Gamma Knife Perfexion radiosurgery system

Mancosu¹,

Reggiori²,

Stravato³

et al. 2015

Medical Physics

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Purpose: To evaluate the new commercial PTW-60019 synthetic single-crystal microDiamond detector (PTW, Freiburg, Germany) for relative dosimetry measurements on a clinical Leksell Gamma Knife Perfexion radiosurgery system. Methods: Detector output ratios (DORs) for 4 and 8 mm beams were measured using a micro- Diamond (PTW-60019), a stereotactic unshielded diode [IBA stereotactic field detector (SFD)], a shielded diode (IBA photon field detector), and GafChromic EBT3 films. Both parallel and transversal acquisition directions were considered for PTW-60019 measurements. Measured DORs were compared to the new output factor reference values for Gamma Knife Perfexion (0.814 and 0.900 for 4 and 8 mm, respectively). Profiles in the three directions were also measured for the 4 mm beam to evaluate full width at half maximum (FWHM) and penumbra and to compare them with the corresponding Leksell GammaPlan profiles. Results: FWHM and penumbra for PTW-60019 differed from the calculated values by less than 0.2 and 0.3 mm, for the parallel and transversal acquisitions, respectively. GafChromic films showed FWHM and penumbra within 0.1 mm. The output ratio obtained with the PTW-60019 for the 4 mm field was 1.6% greater in transverse direction compared to the nominal value. Comparable differences up to 0.8% and 1.0% for, respectively, GafChromic films and SFD were found. Conclusions: The microDiamond PTW-60019 is a suitable detector for commissioning and routine use of Gamma Knife with good agreement of both DORs and profiles in the three directions

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Section: Discussionmentioning

confidence: 99%

Evaluation of a synthetic single‐crystal diamond detector for relative dosimetry on the Leksell Gamma Knife Perfexion radiosurgery system

Mancosu¹,

Reggiori²,

Stravato³

et al. 2015

Medical Physics

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“…Most of the simulations performed (Cheung et al 1998, 1999a, 1999b, Xiaowei and Chunxiang 1999, Moskvin et al 2002 have pointed out a good agreement with the GP predictions in the case of a homogeneous phantom. However, differences reaching 25% are found for phantoms with inhomogeneities, near tissue interfaces and dose edges (Cheung et al 2001).…”

Section: Introductionmentioning

confidence: 67%

“…In addition to the dose profiles around the isocenter of the GK, the output factors for the 4, 8 and 14 mm helmets have been obtained. Our findings have been compared with various results obtained with other MC codes, such as EGS4 (Cheung et al 1999a, 1999b, Xiaowei and Chunxiang 1999 or PENELOPE (Moskvin et al 2002), predicted with GP (Elekta 1992, 1998 or measured with different techniques (Ma et al 2000, Tsai et al 2003. Figure 1 shows a scheme of the simplified model of the source channel of the GK.…”

Section: Introductionmentioning

confidence: 87%

A simplified model of the source channel of the Leksell Gamma Knife®: testing multisource configurations with PENELOPE

Aldweri¹,

Lallena²

2004

Phys. Med. Biol.

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A simplification of the source channel geometry of the Leksell Gamma Knife , recently proposed by the authors and checked for a single source configuration (Al-Dweri et al 2004), has been used to calculate the dose distributions along the x, y and z axes in a water phantom with a diameter of 160 mm, for different configurations of the Gamma Knife including 201, 150 and 102 unplugged sources. The code PENELOPE (v. 2001) has been used to perform the Monte Carlo simulations. In addition, the output factors for the 14, 8 and 4 mm helmets have been calculated. The results found for the dose profiles show a qualitatively good agreement with previous ones obtained with EGS4 and PENELOPE (v. 2000) codes and with the predictions of GammaPlan . The output factors obtained with our model agree within the statistical uncertainties with those calculated with the same Monte Carlo codes and with those measured with different techniques. Owing to the accuracy of the results obtained and to the reduction in the computational time with respect to full geometry simulations (larger than a factor 15), this simplified model opens the possibility to use Monte Carlo tools for planning purposes in the Gamma Knife .

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“…It is important that the electronic inequilibrium and secondary scattering are taken into account properly. Studies on MC simulations are mainly for the prior LGK systems because the collimator system for prior LGK models is relatively simpler to implement 5 , 6 , 7 , 8 , 9 . To simulate prior LGK, only one dataset of the phase space of photon beams at the distal source channel is needed since this phase space is identical for all 201 sources.…”

Section: Introductionmentioning

confidence: 99%

Development of a Monte Carlo model for treatment planning dose verification of the Leksell Gamma Knife Perfexion radiosurgery system

Yuan

Zheng

Sohn

et al. 2016

J Applied Clin Med Phys

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Detailed Monte Carlo (MC) modeling of the Leksell Gamma Knife (GK) Perfexion (PFX) collimator system is the only accurate ab initio approach appearing in the literature. As a different approach, in this work, we present a MC model based on film measurement. By adjusting the model parameters and fine‐tuning the derived fluence map for each individual source to match the manufacturer's ring output factors, we created a reasonable virtual source model for MC simulations to verify treatment planning dose for the GK PFX radiosurgery system. The MC simulation model was commissioned by simple single shots. Dose profiles and both ring and collimator output factors were compared with the treatment planning system (TPS). Good agreement was achieved for dose profiles especially for the region of plateau (<2%), while larger difference (<5%) came from the penumbra region. The maximum difference of the calculated output factor was within 0.7%. The model was further validated by a clinical test case. Good agreement was obtained. The DVHs for brainstem and the skull were almost identical and, for the target, the volume covered by the prescription (12.5 Gy to 50% isodose line) was 95.6% from MC calculation versus 100% from the TPS.PACS number(s): 87.55.dk

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Monte Carlo calculated output factors of a Leksell Gamma Knife unit

Cited by 37 publications

References 1 publication

Evaluation of a synthetic single‐crystal diamond detector for relative dosimetry on the Leksell Gamma Knife Perfexion radiosurgery system

Evaluation of a synthetic single‐crystal diamond detector for relative dosimetry on the Leksell Gamma Knife Perfexion radiosurgery system

A simplified model of the source channel of the Leksell Gamma Knife®: testing multisource configurations with PENELOPE

Development of a Monte Carlo model for treatment planning dose verification of the Leksell Gamma Knife Perfexion radiosurgery system

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