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Ungerer A, Staufer T, Schmutzler O, Körnig C, Rothkamm K, Grüner F. X-ray-Fluorescence Imaging for In Vivo Detection of Gold-Nanoparticle-Labeled Immune Cells: A GEANT4 Based Feasibility Study. Cancers (Basel) 2021; 13:5759. [PMID: 34830917 PMCID: PMC8616134 DOI: 10.3390/cancers13225759] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Revised: 11/12/2021] [Accepted: 11/15/2021] [Indexed: 12/21/2022] Open
Abstract
The growing field of cellular therapies in regenerative medicine and oncology calls for more refined diagnostic tools that are able to investigate and monitor the function and success of said therapies. X-ray Fluorescence Imaging (XFI) can be applied for molecular imaging with nanoparticles, such as gold nanoparticles (GNPs), which can be used in immune cell tracking. We present a Monte Carlo simulation study on the sensitivity of detection and associated radiation dose estimations in an idealized setup of XFI in human-sized objects. Our findings demonstrate the practicability of XFI in human-sized objects, as immune cell tracking with a minimum detection limit of 4.4 × 105 cells or 0.86 μg gold in a cubic volume of 1.78 mm3 can be achieved. Therefore, our results show that the current technological developments form a good basis for high sensitivity XFI.
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Affiliation(s)
- Arthur Ungerer
- University Medical Center Hamburg-Eppendorf, Department of Radiotherapy and Radiation Oncology, Medical Faculty, University of Hamburg, Martinistraße 52, 20246 Hamburg, Germany; (A.U.); (K.R.)
- Universität Hamburg and Center for Free-Electron Laser Science (CFEL), Institute for Experimental Physics, Faculty of Mathematics, Informatics and Natural Sciences, University of Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany; (T.S.); (O.S.); (C.K.)
| | - Theresa Staufer
- Universität Hamburg and Center for Free-Electron Laser Science (CFEL), Institute for Experimental Physics, Faculty of Mathematics, Informatics and Natural Sciences, University of Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany; (T.S.); (O.S.); (C.K.)
| | - Oliver Schmutzler
- Universität Hamburg and Center for Free-Electron Laser Science (CFEL), Institute for Experimental Physics, Faculty of Mathematics, Informatics and Natural Sciences, University of Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany; (T.S.); (O.S.); (C.K.)
| | - Christian Körnig
- Universität Hamburg and Center for Free-Electron Laser Science (CFEL), Institute for Experimental Physics, Faculty of Mathematics, Informatics and Natural Sciences, University of Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany; (T.S.); (O.S.); (C.K.)
| | - Kai Rothkamm
- University Medical Center Hamburg-Eppendorf, Department of Radiotherapy and Radiation Oncology, Medical Faculty, University of Hamburg, Martinistraße 52, 20246 Hamburg, Germany; (A.U.); (K.R.)
| | - Florian Grüner
- Universität Hamburg and Center for Free-Electron Laser Science (CFEL), Institute for Experimental Physics, Faculty of Mathematics, Informatics and Natural Sciences, University of Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany; (T.S.); (O.S.); (C.K.)
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Choi HJ, Jang JW, Shin WG, Park H, Incerti S, Min CH. Development of integrated prompt gamma imaging and positron emission tomography system for in vivo 3-D dose verification: a Monte Carlo study. Phys Med Biol 2020; 65:105005. [PMID: 32235068 DOI: 10.1088/1361-6560/ab857c] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
An accurate knowledge of in vivo proton dose distribution is key to fully utilizing the potential advantages of proton therapy. Two representative indirect methods for in vivo range verification, namely, prompt gamma (PG) imaging and positron emission tomography (PET), are available. This study proposes a PG-PET system that combines the advantages of these two methods and presents detector geometry and background reduction techniques optimized for the PG-PET system. The characteristics of the secondary radiations emitted by a water phantom by interaction with a 150 MeV proton beam were analysed using Geant4.10.00, and the 2-D PG distributions were obtained and assessed for different detector geometries. In addition, the energy window (EW), depth-of-interaction (DOI), and time-of-flight (TOF) techniques are proposed as the background reduction techniques. To evaluate the performance of the PG-PET system, the 3-D dose distribution in the water phantom caused by two proton beams of energies 80 MeV and 100 MeV was verified using 16 optimal detectors. The thickness of the parallel-hole tungsten collimator of pitch 8 mm and width 7 mm was determined as 200 mm, and that of the GAGG scintillator was determined as 30 mm, by an optimization study. Further, 3-7 MeV and 2-7 MeV were obtained as the optimal EWs when the DOI and both the DOI and TOF techniques were applied for data processing, respectively; the detector performances were improved by about 38% and 167%, respectively, compared with that when applying only the 3-5 MeV EW. In this study, we confirmed that the PG distribution can be obtained by simply combining the 2-D parallel hole collimator and the PET detector module. In the future, we will develop an accurate 3-D dose evaluation technique using deep learning algorithms based on the image sets of dose, PG, and PET distributions for various proton energies.
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Affiliation(s)
- Hyun Joon Choi
- Department of Radiation Convergence Engineering, Yonsei University, Wonju 26493, Republic of Korea
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Park H, Choi HJ, Hee Min C, Kim JI. Monte Carlo simulation of a 2D dynamic multileaf collimator to improve the plan quality in radiotherapy plan: a proof-of-concept study. Phys Med Biol 2019; 64:245009. [PMID: 31726432 DOI: 10.1088/1361-6560/ab57c4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The leaf width of a multileaf collimator (MLC) determines the dose conformity to the target volume. The objective of this study was to investigate the feasibility of a two-dimensional dynamic MLC (2DDMLC) to improve the treatment plan quality with a fixed leaf width. The treatment head of the Clinac™ linear accelerator with the Millennium 120™ MLC was modelled with the Geant4 (for GEometry ANd Tracking) tollkit using the Monte Carlo (MC) method. The 2DDMLC produces a beam aperture by moving the MLC bank vertically to the leaf movement. Thus, the effect of the 2DDMLC motion on beam divergence and beam fluence resolution was evaluated by comparing the dose distributions between the conventional MLC motion and the 2DDMLC. Finally, the 2DDMLC was employed for dynamic conformal arc therapy for 13 brain cancer patients. The dose-volumetric parameters, including the dose delivered to 98% of the target volume (D 98%), percent volume given 20% of the prescribed dose (V 20%), and conformity index (CI) were compared with those of the conventional MLC. For the 6 MV beam of the MC model, the depth dose and lateral dose distribution differed by less than 2% between the simulation and measurement. The 2DDMLC did not significantly influence beam divergence and sharpened the beam. In clinical use, the dose delivered to the target was almost identical between the 2DDMLC and conventional MLC (D 98% = 29.74 Gy versus 29.71 Gy, p = 0.18). The CI was improved with the use of the 2DDMLC (CI = 1.49 versus 1.47, p = 0.14). Moreover, irradiation of normal tissue was reduced with the 2DDMLC compared with conventional MLC (V 20% = 17.22% versus 17.45%, p < 0.001). The 2DDMLC improved the dose conformity to the target volume and reduced the irradiation of the normal tissue compared with the conventional MLC.
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Affiliation(s)
- Hyojun Park
- Department of Radiation Convergence Engineering, Yonsei University, Wonju, Republic of Korea
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Kim JI, Cho JD, Son J, Choi CH, Wu HG, Park JM. Contact lens-type ocular in vivo dosimeter for radiotherapy. Med Phys 2019; 47:722-735. [PMID: 31743441 DOI: 10.1002/mp.13932] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2019] [Revised: 10/26/2019] [Accepted: 11/13/2019] [Indexed: 12/31/2022] Open
Abstract
PURPOSE This study aimed to (a) develop a contact lens-type ocular in vivo dosimeter (CLOD) that can be worn directly on the eye and (b) assess its dosimetric characteristics and biological stability for radiation therapy. METHODS The molder of a soft contact lens was directly used to create the dosimeter, which included a radiation-sensitive component - an active layer similar to a radiochromic film - to measure the delivered dose. A flatbed scanner with a reflection mode was used to measure the change in optical density due to irradiation. The sensitivity, energy, dose rate, and angular dependence were tested, and the uncertainty in determining the dose was calculated using error propagation analysis. Sequential biological stability tests, specifically, cytotoxicity and ocular irritation tests, were conducted to ensure the safe application of the CLOD to patients. RESULTS The dosimeter demonstrated high sensitivity in the low dose region, and the sensitivity linearly decreased with the dose. The responses obtained for the 10 and 15 MV photon beams were 1.7% and 1.9% higher compared to the 6 MV photon beam. A strong dose rate dependence was not obtained for the CLOD. Angular dependence was observed from 90° to 180° with a difference in response from 1% to 2%. The total uncertainty in error propagation analysis decreased as a function of the dose in the red channel. For a dose range of 0 to 50 cGy, the total uncertainties for 5, 10, and 50 cGy were 14.2%, 8.9%, and 5%, respectively. Quantitative evaluation using the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) method presented no cytotoxicity. Further, no corneal opacity, iris reaction, or conjunctival inflammation was observed. CONCLUSIONS The CLOD is the first dosimeter that can be worn close to the eye. The results of cytotoxicity and irritation tests indicate that it is a stable medical device. The evaluation of dose characteristics in open field conditions shows that the CLOD can be applied to an in vivo dosimeter in radiotherapy.
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Affiliation(s)
- Jung-In Kim
- Department of Radiation Oncology, Seoul National University Hospital, Seoul, 03080, Republic of Korea.,Institute of Radiation Medicine, Seoul National University Medical Research Center, Seoul, 03080, Republic of Korea.,Biomedical Research Institute, Seoul National University Hospital, Seoul, 03080, Republic of Korea
| | - Jin-Dong Cho
- Department of Radiation Oncology, Seoul National University Hospital, Seoul, 03080, Republic of Korea.,Institute of Radiation Medicine, Seoul National University Medical Research Center, Seoul, 03080, Republic of Korea.,Department of Radiation Oncology, College of Medicine, Yonsei University, Seoul, 03722, Republic of Korea
| | - Jaeman Son
- Department of Radiation Oncology, Seoul National University Hospital, Seoul, 03080, Republic of Korea.,Biomedical Research Institute, Seoul National University Hospital, Seoul, 03080, Republic of Korea
| | - Chang Heon Choi
- Department of Radiation Oncology, Seoul National University Hospital, Seoul, 03080, Republic of Korea.,Institute of Radiation Medicine, Seoul National University Medical Research Center, Seoul, 03080, Republic of Korea.,Biomedical Research Institute, Seoul National University Hospital, Seoul, 03080, Republic of Korea
| | - Hong-Gyun Wu
- Department of Radiation Oncology, Seoul National University Hospital, Seoul, 03080, Republic of Korea.,Institute of Radiation Medicine, Seoul National University Medical Research Center, Seoul, 03080, Republic of Korea.,Biomedical Research Institute, Seoul National University Hospital, Seoul, 03080, Republic of Korea.,Department of Radiation Oncology, Seoul National University College of Medicine, Seoul, 03080, Republic of Korea
| | - Jong Min Park
- Department of Radiation Oncology, Seoul National University Hospital, Seoul, 03080, Republic of Korea.,Institute of Radiation Medicine, Seoul National University Medical Research Center, Seoul, 03080, Republic of Korea.,Biomedical Research Institute, Seoul National University Hospital, Seoul, 03080, Republic of Korea.,Robotics Research Laboratory for Extreme Environments, Advanced Institute of Convergence Technology, Suwon, 16229, Republic of Korea
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Choi HJ, Park H, Yi CY, Kim BC, Shin WG, Min CH. Determining the energy spectrum of clinical linear accelerator using an optimized photon beam transmission protocol. Med Phys 2019; 46:3285-3297. [PMID: 31055830 DOI: 10.1002/mp.13569] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Revised: 04/09/2019] [Accepted: 04/25/2019] [Indexed: 12/29/2022] Open
Abstract
PURPOSE The complex beam delivery techniques for patient treatment using a clinical linear accelerator (linac) may result in variations in the photon spectra, which can lead to dosimetric differences in patients that cannot be accounted for by current treatment planning systems (TPSs). Therefore, precise knowledge of the fluence and energy spectrum (ES) of the therapeutic beam is very important. However, owing to the high energy and flux of the beam, the ES cannot be measured directly, and validation of the spectrum modeled in the TPS is difficult. The aim of this study is to develop an efficient beam transmission measurement procedure for accurately reconstructing the ES of a therapeutic x-ray beam generated by a clinical linac. METHODS The attenuation of a 6 MV photon beam from an Elekta Synergy Platform clinical linac through different thicknesses of graphite and lead was measured using an ion chamber. The response of the ion chamber as a function of photon energy was obtained using the Monte Carlo (MC) method in the Geant4 simulation code. Using the curves obtained in the photon beam transmission measurements and the ion chamber energy response, the ES was reconstructed using an iterative algorithm based on a mathematical model of the spectrum. To evaluate the accuracy of the spectrum reconstruction method, the reconstructed ES (ESrecon ) was compared to that determined by the MC simulation (ESMC ). RESULTS The ion chamber model in the Geant4 simulation was well validated by comparing the ion chamber perturbation factors determined by the TRS-398 calibration protocol and EGSnrc; the differences were within 0.57%. The number of transmission measurements was optimized to 10 for efficient spectrum reconstruction according to the rate of increase in the spectrum reconstruction accuracy. The distribution of ESrecon obtained using the measured transmission curves was clearly similar to the reference, ESMC , and the dose distributions in water calculated using ESrecon and ESMC were similar within a 2% local difference. However, in a heterogeneous medium, the dose discrepancy between them was >5% when a complex beam delivery technique composed of 171 control points was used. CONCLUSIONS The proposed measurement procedure required a total time of approximately 1 h to obtain and analyze 20 transmission measurements. In addition, it was confirmed that the transmission curve of high-Z materials influences the accuracy of spectrum reconstruction more than that of low-Z materials. A well-designed transmission measurement protocol suitable for clinical environments could be an essential tool for better dosimetric accuracy in patient treatment and for periodic verification of the beam quality.
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Affiliation(s)
- Hyun Joon Choi
- Department of Radiation Convergence Engineering, Yonsei University, 1 Yeonsedae-gil, Heungeop-myeon, Wonju, 26493, Korea
| | - Hyojun Park
- Department of Radiation Convergence Engineering, Yonsei University, 1 Yeonsedae-gil, Heungeop-myeon, Wonju, 26493, Korea
| | - Chul Young Yi
- Center for Ionizing Radiation, Korea Research Institute of Standards and Science, Daejeon 34113, Korea
| | - Byoung-Chul Kim
- Center for Ionizing Radiation, Korea Research Institute of Standards and Science, Daejeon 34113, Korea
| | - Wook-Geun Shin
- Department of Radiation Convergence Engineering, Yonsei University, 1 Yeonsedae-gil, Heungeop-myeon, Wonju, 26493, Korea
| | - Chul Hee Min
- Department of Radiation Convergence Engineering, Yonsei University, 1 Yeonsedae-gil, Heungeop-myeon, Wonju, 26493, Korea
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