scholarly journals The Impact of Normalization Isodose Line (NIDL) on Dose Distribution in Intracranial Tumors Treated with CyberKnife

2019 ◽  
Vol 4 (2) ◽  
Author(s):  
Zhitao Dai ◽  
Cui Yang ◽  
Wei Jiang ◽  
Man Zhao ◽  
Wuzhou Li ◽  
...  
Keyword(s):  
Dose Distribution ◽  
Intracranial Tumors ◽  
The Impact

Experimental evaluation of the impact of low tesla transverse magnetic field on dose distribution in presence of tissue interfaces

2018 ◽  
Vol 53 ◽  
pp. 80-85 ◽  
Author(s):  
Davide Cusumano ◽  
Stefania Teodoli ◽  
Francesca Greco ◽  
Andrea Fidanzio ◽  
Luca Boldrini ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Transverse Magnetic Field ◽  
Dose Distribution ◽  
Experimental Evaluation ◽  
Transverse Magnetic ◽  
The Impact ◽  
Tissue Interfaces

TH-C-T-6E-10: The Impact of Calculation Grid Size On the Accuracy of IMRT Dose Distribution

2005 ◽  
Vol 32 (6Part21) ◽  
pp. 2168-2168
Author(s):  
H Chung ◽  
H Jin ◽  
C Liu ◽  
J Palta ◽  
T Suh ◽  
...  
Keyword(s):  
Dose Distribution ◽  
Grid Size ◽  
The Impact ◽  
Calculation Grid

Modeling the dose distribution in a human brain structure using CT images on the surface of Mars

2020 ◽  
Author(s):  
Salman Khaksarighiri ◽  
Jingnan Guo ◽  
Robert Wimmer-Schweingruber ◽  
Lennart Rostl
Keyword(s):  
Radiation Dose ◽  
Human Brain ◽  
Brain Structure ◽  
Dose Distribution ◽  
Cosmic Radiation ◽  
Cosmic Ray ◽  
Ct Images ◽  
Human Brains ◽  
The Impact ◽  
The Brain

<p>One of the most important steps in the near-future space age will be a manned mission to Mars. Unfortunately, such a mission will cause astronauts to be exposed to unavoidable cosmic radiation in deep space and on the surface of Mars. Thus a better understanding of the radiation environment for a Mars mission and the consequent biological impacts on humans, in particular the human brains, is critical. To investigate the impact of cosmic radiation on human brains and the potential influence on the brain functions, we model and study the cosmic particle-induced radiation dose in a realistic head structure. Specifically speaking, 134 slices of computed tomography (CT) images of an actual human head have been used as a 3D phantom in Geant4 (GEometry ANd Tracking) which is a Monte Carlo tool simulating energetic particles impinging into different parts of the brain and deliver radiation dose therein. As a first step, we compare the influence of different brain structures (e.g., with or without bones, with or without soft tissues) to the resulting dose therein to demonstrate the necessity of using a realistic brain structure for our investigation. Afterwards, we calculate energy-dependent functions of dose distribution for the most important (most abundant and most biologically-relevant) particle types encountered in space and on Mars such as protons, Helium ions and neutrons. These functions are then used to fold with Galactic Cosmic Ray (GCR) spectra on the surface of Mars for obtaining the dose rate distribution at different lobes of the human brain. Different GCR spectra during various solar cycle conditions have also been studied and compared.</p>

scholarly journals A Probability-Based Investigation on the Setup Robustness of Pencil-beam Proton Radiation Therapy for Skull-Base Meningioma

2021 ◽  
Vol 7 (3) ◽  
pp. 34-45
Author(s):  
Wei Zou ◽  
Goldie Kurtz ◽  
Mayisha Nakib ◽  
Brendan Burgdorf ◽  
Murat Alp ◽  
...  
Keyword(s):  
Radiation Therapy ◽  
Skull Base ◽  
Dose Distribution ◽  
Hot Spot ◽  
Published Data ◽  
Pencil Beam ◽  
Planning Techniques ◽  
Setup Errors ◽  
Skull Base Meningioma ◽  
The Impact

Abstract Introduction The intracranial skull-base meningioma is in proximity to multiple critical organs and heterogeneous tissues. Steep dose gradients often result from avoiding critical organs in proton treatment plans. Dose uncertainties arising from setup errors under image-guided radiation therapy are worthy of evaluation. Patients and Methods Fourteen patients with skull-base meningioma were retrospectively identified and planned with proton pencil beam scanning (PBS) single-field uniform dose (SFUD) and multifield optimization (MFO) techniques. The setup uncertainties were assigned a probability model on the basis of prior published data. The impact on the dose distribution from nominal 1-mm and large, less probable setup errors, as well as the cumulative effect, was analyzed. The robustness of SFUD and MFO planning techniques in these scenarios was discussed. Results The target coverage was reduced and the plan dose hot spot increased by all setup uncertainty scenarios regardless of the planning techniques. For 1 mm nominal shifts, the deviations in clinical target volume (CTV) coverage D99% was −11 ± 52 cGy and −45 ± 147 cGy for SFUD and MFO plans. The setup uncertainties affected the organ at risk (OAR) dose both positively and negatively. The statistical average of the setup uncertainties had <100 cGy impact on the plan qualities for all patients. The cumulative deviations in CTV D95% were 1 ± 34 cGy and −7 ± 18 cGy for SFUD and MFO plans. Conclusion It is important to understand the impact of setup uncertainties on skull-base meningioma, as the tumor target has complex shape and is in proximity to multiple critical organs. Our work evaluated the setup uncertainty based on its probability distribution and evaluated the dosimetric consequences. In general, the SFUD plans demonstrated more robustness than the MFO plans in target coverages and brainstem dose. The probability-weighted overall effect on the dose distribution is small compared to the dosimetric shift during single fraction.

scholarly journals SURG-07. Plasmonic gold nanostars to increase the efficiency and specificity of laser interstitial thermal therapy (LITT) in the treatment of brain tumors

2021 ◽  
Vol 3 (Supplement_3) ◽  
pp. iii24-iii25
Author(s):  
Ethan Srinivasan ◽  
Pakawat Chongsathidkiet ◽  
Ren Odion ◽  
Yang Liu ◽  
Eric Sankey ◽  
...  
Keyword(s):  
Ex Vivo ◽  
Thermal Therapy ◽  
Surrounding Tissue ◽  
Intracranial Tumors ◽  
Invasive Treatment ◽  
Laser Interstitial Thermal Therapy ◽  
Gold Nanostars ◽  
Pet Ct ◽  
The Impact

Abstract Introduction Laser interstitial thermal therapy (LITT) is an effective minimally-invasive treatment option for intracranial tumors. Our group produced plasmonics-active gold nanostars (GNS) designed to preferentially accumulate within intracranial tumors and amplify the ablative capacity of LITT while better conforming to tumor boundaries and protecting surrounding tissue. Materials and Methods: The 12nm GNS were synthesized using reduced HAuCl4 with Na3C6H5O7 seeds, mixed with AgNO3, C6H8O6, and HAuCL4, and coated with polyethylene glycol then functionalized with methoxy PEG thiol. CT-2A glioma cells were intracranially implanted into mice, followed 18 days later by IV injection of GNS. PET-CT was performed at 10-minutes, 24-, and 72-hours post-GNS administration, with autoradiography (AR) and histopathology (HP) on sacrifice after the last scan. To test the impact of GNS on LITT coverage capacity in appropriately sized ex vivo models, we utilized agarose gel-based phantoms incorporating control and GNS-infused central “tumors” in multiple shapes. LITT was administered with the NeuroBlate System. Results In vivo, GNS preferentially accumulated within intracranial tumors on PET-CT at the 24- and 72-hour timepoints. AR and HP confirmed high GNS accumulation within tumor. Ex vivo, in cuboid tumor phantoms, the GNS-infused phantom heated 5.5x faster than the control, rising 0.49°C per minute compared to 0.09°C. In a split-cylinder tumor phantom with half containing GNS, the GNS-infused border heated 2x faster and the surrounding area was exposed to 30% lower temperatures. In a GNS-infused star-shaped phantom, the heat spread contoured along phantom boundaries. Conclusion Our results provide evidence for use of GNS to improve the specificity, efficiency, and potentially safety of LITT. The in vivo data support selective accumulation within intracranial tumors, and the GNS-infused phantom experiments demonstrate increased rates of heating within the tumor model, heat contouring to tumor borders, and decreased heating of surrounding regions representing normal structures.

scholarly journals Potential Defects and Improvements of Equivalent Uniform Dose Prediction Model Based on the Analysis of Radiation-Induced Brain Injury

2022 ◽  
Vol 11 ◽  
Author(s):  
Qing-Hua Du ◽  
Jian Li ◽  
Yi-Xiu Gan ◽  
Hui-Jun Zhu ◽  
Hai-Ying Yue ◽  
...  
Keyword(s):  
Brain Injury ◽  
Dose Distribution ◽  
Predictive Ability ◽  
Volume Effect ◽  
Equivalent Uniform Dose ◽  
Critical Dose ◽  
Dose Volume ◽  
Radiation Induced ◽  
Effect Parameter ◽  
The Impact

PurposeTo study the impact of dose distribution on volume-effect parameter and predictive ability of equivalent uniform dose (EUD) model, and to explore the improvements.Methods and MaterialsThe brains of 103 nasopharyngeal carcinoma patients treated with IMRT were segmented according to dose distribution (brain and left/right half-brain for similar distributions but different sizes; VD with different D for different distributions). Predictive ability of EUDVD (EUD of VD) for radiation-induced brain injury was assessed by receiver operating characteristics curve (ROC) and area under the curve (AUC). The optimal volume-effect parameter a of EUD was selected when AUC was maximal (mAUC). Correlations between mAUC, a and D were analyzed by Pearson correlation analysis. Both mAUC and a in brain and half-brain were compared by using paired samples t-tests. The optimal DV and VD points were selected for a simple comparison.ResultsThe mAUC of brain/half-brain EUD was 0.819/0.821 and the optimal a value was 21.5/22. When D increased, mAUC of EUDVD increased, while a decreased. The mAUC reached the maximum value when D was 50–55 Gy, and a was always 1 when D ≥55 Gy. The difference of mAUC/a between brain and half-brain was not significant. If a was in range of 1 to 22, AUC of brain/half-brain EUDV55 Gy (0.857–0.830/0.845–0.830) was always larger than that of brain/half-brain EUD (0.681–0.819/0.691–0.821). The AUCs of optimal dose/volume points were 0.801 (brain D2.5 cc), 0.823 (brain V70 Gy), 0.818 (half-brain D1 cc), and 0.827 (half-brain V69 Gy), respectively. Mean dose (equal to EUDVD with a = 1) of high-dose volume (V50 Gy–V60 Gy) was superior to traditional EUD and dose/volume points.ConclusionVolume-effect parameter of EUD is variable and related to dose distribution. EUD with large low-dose volume may not be better than simple dose/volume points. Critical-dose-volume EUD could improve the predictive ability and has an invariant volume-effect parameter. Mean dose may be the case in which critical-dose-volume EUD has the best predictive ability.

Integrin inhibition as a potential target for invasive meningiomas.

2013 ◽  
Vol 31 (15_suppl) ◽  
pp. e22140-e22140 ◽  
Author(s):  
Christian Mawrin ◽  
Elmar Kirches ◽  
Anette Wilisch-Neumann
Keyword(s):  
Cell Migration ◽  
Tumor Recurrence ◽  
Migration And Invasion ◽  
Intracranial Tumors ◽  
Meningioma Cell ◽  
Tumor Blood Vessels ◽  
High Doses ◽  
The Impact ◽  
Integrin Inhibitor

e22140 Background: Meningiomas are frequent intracranial tumors, which may show high rates of tumor recurrence after surgery. Additionally, a number of meningiomas show aggressive clinical behaviour with significant reduction of patient´s survival. In the present study, the impact of cilengitide, an integrin inhibitor, on migration, proliferation and radiosensitization of meningioma cells was evaluated. Methods: We analyzed integrin expression in tissue microarray samples and the anti-meningioma properties of cilengitide in vitro using different meningioma cell lines including pairs with knockdown of NF2, and tested the substance in subcutaneous and intracranial orthotopic nude mice models. Results: The predominantly expressed integrin in the tumor cells was αvβ5, while αvβ3 was mainly restricted to tumor blood vessels. One µM cilengitide was sufficient to significantly inhibit meningioma cell migration and invasion in vitro. On the other hand, even high doses of the drug resulted in only mildly reduced proliferation/survival of the cells, although the effects on cell survival were improved by irradiation. A daily dosage of up to 75 mg/kg did not affect tumor volumes in both mouse models. However, a combination of 75 mg/kg cilengitide daily and irradiation (2 x 5 Gy) led to a stronger reduction of MRI estimated tumor volumes in the intracranial model (67%, p<0.01), as compared to the corresponding reduction reached by irradiation alone (55%, p<0.05). Conclusions: These data show that the integrin inhibitor has mild cytostatic properties in meningioma cells, but strongly inhibits cell migration/invasion. In combination with radiotherapy it may help to further reduce meningioma tumor recurrence.

scholarly journals Investigating the Impact of Knee Prosthesis in Patients’ Body on Radiation Dose Distribution: A Monte Carlo Approach

2019 ◽  
Author(s):  
M R Bayatiani ◽  
F Seif ◽  
S Hamidi ◽  
S Bagheri
Keyword(s):  
Monte Carlo ◽  
Titanium Alloy ◽  
Dose Reduction ◽  
Alloy Steel ◽  
Dose Distribution ◽  
Knee Prosthesis ◽  
Cobalt Chromium ◽  
Radiotherapy Dose ◽  
Cobalt Chromium Molybdenum ◽  
The Impact

Introduction: Metal prostheses in patients affect the radiotherapy dose distribution. Metal prostheses with high density and atomic number cause major changes in scattering and attenuation of radiation. The present study aims to assess the impact of metal knee prosthesis with various dimensions and materials on radiotherapy dose distribution. Material and Methods: In this research, the Varian Linac and water phantom were simulated using the MCNPX code. Dose distribution of photon beam in a water phantom, with and without the presence of knee prostheses made of cobalt-chromium-molybdenum alloy, steel, titanium, and titanium alloy used in men and women was investigated using the Monte Carlo simulation.Results: The prosthesis led to an increase in dose in comparison with cases that there was used no prosthesis. According to values of the depth dose percentage, the maximum dose increase was found to be 6.8%, 6.1%, 4%, and 4.29%, and dose reduction 41.18%, 40.66%, 37.76%, and 37.51% for prosthetics with men’s knee dimensions made of cobalt-chromium-molybdenum alloy, steel, titanium alloy, and titanium, respectively. Above all, does increasing to 6.4%, 5.9%, 3.8%, and 3.94% and doses reducing to 40.87%, 40.36%, 36.94%, and 36.69 were observed in prosthetics for women. The highest amount of dose reduction for men’s prostheses made of mentioned materials was found to be 48.75%, 47.7%, 45%, and 45.8%, respectively. In addition, it was 46.36%, 45.8%, 43.8%, and 43.95% for women’s prostheses, respectively.Conclusion: Material will have a significant impact if a part of the knee bone places behind the prosthesis. According to the obtained values, it is recommended to utilize prostheses made of titanium and titanium alloys for knee arthroplasty. The prosthesis can either increase or decrease dose in tumor or lead to increase dose at organs at risk.

EXTH-19. INTEGRATION OF PLASMONIC GOLD NANOSTARS AND LASER INTERSTITIAL THERMAL THERAPY (LITT) FOR SPECIFIC AND AMPLIFIED ABLATION OF BRAIN TUMORS

2021 ◽  
Vol 23 (Supplement_6) ◽  
pp. vi167-vi167
Author(s):  
Ethan Srinivasan ◽  
Pakawat Chongsathidkiet ◽  
Ren Odion ◽  
Yang Liu ◽  
Eric Sankey ◽  
...  
Keyword(s):  
Ex Vivo ◽  
Thermal Therapy ◽  
Surrounding Tissue ◽  
Intracranial Tumors ◽  
Invasive Treatment ◽  
Laser Interstitial Thermal Therapy ◽  
Gold Nanostars ◽  
Pet Ct ◽  
The Impact

Abstract INTRODUCTION Laser interstitial thermal therapy (LITT) is an effective minimally-invasive treatment option for intracranial tumors. Our group produced plasmonics-active gold nanostars (GNS) designed to preferentially accumulate within intracranial tumors and amplify the ablative capacity of LITT while better conforming to tumor boundaries and protecting surrounding tissue. MATERIALS AND METHODS The 12nm GNS were synthesized using reduced HAuCl4 with Na3C6H5O7 seeds, mixed with AgNO3, C6H8O6, and HAuCL4, and coated with polyethylene glycol then functionalized with methoxy PEG thiol. CT-2A glioma cells were intracranially implanted into mice, followed 18 days later by IV injection of GNS. PET-CT was performed at 10-minutes, 24-, and 72-hours post-GNS administration, with autoradiography (AR) and histopathology (HP) on sacrifice after the last scan. To test the impact of GNS on LITT coverage capacity in appropriately sized ex vivo models, we utilized agarose gel-based phantoms incorporating control and GNS-infused central “tumors” in multiple shapes. LITT was administered with the NeuroBlate System. RESULTS In vivo, GNS preferentially accumulated within intracranial tumors on PET-CT at the 24- and 72-hour timepoints. AR and HP confirmed high GNS accumulation within tumor. Ex vivo, in cuboid tumor phantoms, the GNS-infused phantom heated 5.5x faster than the control, rising 0.49°C per minute compared to 0.09°C. In a split-cylinder tumor phantom with half containing GNS, the GNS-infused border heated 2x faster and the surrounding area was exposed to 30% lower temperatures. In a GNS-infused star-shaped phantom, the heat spread contoured along phantom boundaries. CONCLUSIONS Our results provide evidence for use of GNS to improve the specificity, efficiency, and potentially safety of LITT. The in vivo data support selective accumulation within intracranial tumors, and the GNS-infused phantom experiments demonstrate increased rates of heating within the tumor model, heat contouring to tumor borders, and decreased heating of surrounding regions representing normal structures.

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