Low‐Z linac targets for low‐MV gold nanoparticle radiation therapy

Tsiamas, Panagiotis; Mishra, Pankaj; Cifter, F; Berbeco, R.; Marcus, Karen J.; Sajo, Erno; Zygmanski, Piotr

doi:10.1118/1.4859335

Cited by 18 publications

(24 citation statements)

References 32 publications

(59 reference statements)

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“…13,18,37,[40][41][42] Our previous theoretical calculations combining Monte Carlo with the analytical microdosimetry calculation described above 13,37 predict a roughly 50%-150% increase in dose to the tumor endothelial cells, for a 6 MV standard (Cu/W) beam. Factors that affect the therapeutic efficacy include depth in tissue, 13 removal of the FFF, and the energy of the electron beam incident on the target.…”

Section: B An Analytical Calculation Methods For Endothelial Dose Ementioning

confidence: 99%

Low Z target switching to increase tumor endothelial cell dose enhancement during gold nanoparticle-aided radiation therapy

et al. 2015

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Purpose: Previous studies have introduced gold nanoparticles as vascular-disrupting agents during radiation therapy. Crucial to this concept is the low energy photon content of the therapy radiation beam. The authors introduce a new mode of delivery including a linear accelerator target that can toggle between low Z and high Z targets during beam delivery. In this study, the authors examine the potential increase in tumor blood vessel endothelial cell radiation dose enhancement with the low Z target. Methods: The authors use Monte Carlo methods to simulate delivery of three different clinical photon beams: (1) a 6 MV standard (Cu/W) beam, (2) a 6 MV flattening filter free (Cu/W), and (3) a 6 MV (carbon) beam. The photon energy spectra for each scenario are generated for depths in tissue-equivalent material: 2, 10, and 20 cm. The endothelial dose enhancement for each target and depth is calculated using a previously published analytic method. Results: It is found that the carbon target increases the proportion of low energy (<150 keV) photons at 10 cm depth to 28% from 8% for the 6 MV standard (Cu/W) beam. This nearly quadrupling of the low energy photon content incident on a gold nanoparticle results in 7.7 times the endothelial dose enhancement as a 6 MV standard (Cu/W) beam at this depth. Increased surface dose from the low Z target can be mitigated by well-spaced beam arrangements. Conclusions: By using the fast-switching target, one can modulate the photon beam during delivery, producing a customized photon energy spectrum for each specific situation. C 2016 American Association of Physicists in Medicine. [http://dx

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Section: B An Analytical Calculation Methods For Endothelial Dose Ementioning

confidence: 99%

Low Z target switching to increase tumor endothelial cell dose enhancement during gold nanoparticle-aided radiation therapy

et al. 2015

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“…For convenience, we arrange the literature according to the following order: general radiation transport aspects relevant for nanoscale simulations, [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22] macroscopic dose enhancement in contrast agents and dose perturbation at high-Z material interfaces, radiation transport for nanoscopic dose enhancement of GNP, [46][47][48][49][50][51][52][53][54][55][56][57][58] radiobiological and clinical aspects of GNPT, [59][60][61][62][63][64][65][66][67] application of Monte Carlo (MC) simulations to cellular environment, [68][69][70] modification of linear accelerator spectra to maximize dose enhancement 71 and GNPT using other than X-ray therapeutic beams (proton, electron). …”

Section: Introductionmentioning

confidence: 99%

“…New low energy target beamlines with energies down to 2.5 MV and beryllium or diamond targets can additionally increase the enhancement by additional factor of about 2. 71 …”

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confidence: 99%

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Nanoscale radiation transport and clinical beam modeling for gold nanoparticle dose enhanced radiotherapy (GNPT) using X-rays

Zygmanski¹,

Sajo²

2016

BJR

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Cite this article as: Zygmanski P, Sajo E. Nanoscale radiation transport and clinical beam modeling for gold nanoparticle dose enhanced radiotherapy (GNPT) using X-rays. Br J Radiol 2016; 89: 20150200. REVIEW ARTICLENanoscale radiation transport and clinical beam modeling for gold nanoparticle dose enhanced radiotherapy (GNPT) using X-rays ABSTRACTWe review radiation transport and clinical beam modelling for gold nanoparticle dose-enhanced radiotherapy using X-rays. We focus on the nanoscale radiation transport and its relation to macroscopic dosimetry for monoenergetic and clinical beams. Among other aspects, we discuss Monte Carlo and deterministic methods and their applications to predicting dose enhancement using various metrics.

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“…The vertical line at 0.2 cm in Figure 4 represents the border of the irradiation field. The slight increase and decrease of the DER in the region outside of the field visible in Figure 4 (left) may be explained by (off-axis distant dependent) spectral changes of the incoming 100 kVp beam due to scattering (Tsiamas et al 2014). Electron emission by gold is higher for a beam with larger spectral components around 20–40 keV with consequent larger dose enhancement.…”

Section: Resultsmentioning

confidence: 99%

Kilovoltage radiosurgery with gold nanoparticles for neovascular age-related macular degeneration (AMD): a Monte Carlo evaluation

Brivio

Zygmanski

Arnoldussen³

et al. 2015

Phys. Med. Biol.

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This work uses Monte Carlo radiation transport simulation to assess the potential benefits of gold nanoparticles (AuNP) in the treatment of Neovascular Age-Related Macular Degeneration (AMD) with stereotactic radiosurgery. Clinically, a 100 kVp X-ray beam of 4 mm diameter is aimed at the macula to deliver an ablative dose in a single fraction. In the transport model, AuNP accumulated at the bottom of the macula are targeted with a source representative of the clinical beam in order to provide enhanced dose to the diseased macular endothelial cells. It is observed that, because of the AuNP, the dose to the endothelial cells can be significantly enhanced, allowing for greater sparing of optic nerve, retina and other neighboring healthy tissue. For 20 nm diameter AuNP concentration of 32 mg/g, which has been shown to be achievable in vivo, a dose enhancement ratio (DER) of 1.97 was found to be possible, which could potentially be increased through appropriate optimization of beam quality and/or AuNP targeting. A significant enhancement in dose is seen in the vicinity of the AuNP layer within 30 um, peaked at the AuNP-tissue interface. Different angular tilting of the 4 mm-beam results in a similar enhancement. The DER inside and in the penumbra of the 4 mm irradiation-field are almost the same while the actual delivered dose is more than one order of magnitude lower outside the field leading to normal tissue sparing. The prescribed dose to macular endothelial cells can be delivered using almost half of the radiation allowing reduction of dose to the neighboring organs such as retina/optic nerve by 49% when compared to a treatment without AuNP.

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Low‐Z linac targets for low‐MV gold nanoparticle radiation therapy

Abstract: Low-Z (2.5 MV) GNPT is possible even after accounting for greater beam attenuation for deep-seated tumors (22 cm) and the increased skin dose. Further, it can lead to significant sparing of normal tissue while simultaneously escalating the dose in the tumor cells.

Cited by 18 publications

References 32 publications

Low Z target switching to increase tumor endothelial cell dose enhancement during gold nanoparticle-aided radiation therapy

Low Z target switching to increase tumor endothelial cell dose enhancement during gold nanoparticle-aided radiation therapy

Nanoscale radiation transport and clinical beam modeling for gold nanoparticle dose enhanced radiotherapy (GNPT) using X-rays

Kilovoltage radiosurgery with gold nanoparticles for neovascular age-related macular degeneration (AMD): a Monte Carlo evaluation

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