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Heger G, Dumančić M, Luz I, Vatarescu M, Weizman N, Miller BW, Cooks T, Arazi L. First measurements of radon-220 diffusion in mice tumors, towards treatment planning in diffusing alpha-emitters radiation therapy. Med Phys 2024; 51:5045-5058. [PMID: 38507254 DOI: 10.1002/mp.17020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2023] [Revised: 01/22/2024] [Accepted: 02/21/2024] [Indexed: 03/22/2024] Open
Abstract
BACKGROUND Diffusing alpha-emitters radiation therapy ("Alpha-DaRT") is a new method for treating solid tumors with alpha particles, relying on the release of the short-lived alpha-emitting daughter atoms of radium-224 from interstitial sources inserted into the tumor. Alpha-DaRT tumor dosimetry is governed by the spread of radium's progeny around the source, as described by an approximate framework called the "diffusion-leakage model". The most important model parameters are the diffusion lengths of radon-220 and lead-212, and their estimation is therefore essential for treatment planning. PURPOSE Previous works have provided initial estimates for the dominant diffusion length, by measuring the activity spread inside mice-borne tumors several days after the insertion of an Alpha-DaRT source. The measurements, taken when lead-212 was in secular equilibrium with radium-224, were interpreted as representing the lead-212 diffusion length. The aim of this work is to provide first experimental estimates for the diffusion length of radon-220, using a new methodology. METHODS The diffusion length of radon-220 was estimated from autoradiography measurements of histological sections taken from 24 mice-borne subcutaneous tumors of five different types. Unlike previous studies, the source dwell time inside the tumor was limited to 30 min, to prevent the buildup of lead-212. To investigate the contribution of potential non-diffusive processes, experiments were done in two sets: fourteen in vivo tumors, where during the treatment the tumors were still carried by the mice with active blood supply, and 10 ex-vivo tumors, where the tumors were excised before source insertion and kept in a medium at37 ∘ C $37^\circ {\text{C}}$ with the source inside. RESULTS The measured diffusion lengths of radon-220, extracted by fitting the recorded activity pattern up to 1.5 mm from the source, lie in the range0.25 - 0.6 mm ${0.25-0.6}\nobreakspace {\text{mm}}$ , with no significant difference between the average values measured in in-vivo and ex-vivo tumors:L R n i n - v i v o = 0.40 ± 0.08 mm $L_{Rn}^{in-vivo}=0.40{\pm }0.08\nobreakspace {\text{mm}}$ versusL R n e x - v i v o = 0.39 ± 0.07 mm $L_{Rn}^{ex-vivo}=0.39{\pm }0.07\nobreakspace {\text{mm}}$ . However, in-vivo tumors display an enhanced spread of activity 2-3 mm away from the source. This effect is not explained by the current model and is much less pronounced in ex-vivo tumors. CONCLUSIONS The average measured radon-220 diffusion lengths in both in-vivo and ex-vivo tumors are consistent with published data on the diffusion length of radon in water and lie close to the upper limit of the previously estimated range of0.2 - 0.4 mm $0.2-0.4\nobreakspace {\text{mm}}$ . The observation that close to the source there is no apparent difference between in-vivo and ex-vivo tumors, and the good agreement with the theoretical model in this region suggest that the spread of radon-220 is predominantly diffusive in this region. The departure from the model prediction in in-vivo tumors at large radial distances may hint at potential vascular contribution, which will be the subject of future works.
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Affiliation(s)
- Guy Heger
- Unit of Nuclear Engineering, Faculty of Engineering Sciences, Ben-Gurion University of the Negev, Beersheba, Israel
| | - Mirta Dumančić
- Unit of Nuclear Engineering, Faculty of Engineering Sciences, Ben-Gurion University of the Negev, Beersheba, Israel
- Now at Gerald Bronfman Department of Oncology, Faculty of Medicine and Health Sciences, McGill University, Montreal, Quebec, Canada
| | - Ishai Luz
- The Shraga Segal Department of Microbiology, Immunology, and Genetics, Ben-Gurion University of the Negev, Beersheba, Israel
| | - Maayan Vatarescu
- The Shraga Segal Department of Microbiology, Immunology, and Genetics, Ben-Gurion University of the Negev, Beersheba, Israel
| | - Noam Weizman
- Unit of Nuclear Engineering, Faculty of Engineering Sciences, Ben-Gurion University of the Negev, Beersheba, Israel
- Oncology Department, Radiation Therapy Unit, Hadassah - Hebrew University Medical Center, Jerusalem, Israel
| | - Brian W Miller
- College of Medicine, Department of Radiation Oncology, Department of Medical Imaging, The University of Arizona, Tucson, Arizona, USA
| | - Tomer Cooks
- The Shraga Segal Department of Microbiology, Immunology, and Genetics, Ben-Gurion University of the Negev, Beersheba, Israel
| | - Lior Arazi
- Unit of Nuclear Engineering, Faculty of Engineering Sciences, Ben-Gurion University of the Negev, Beersheba, Israel
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Nojima H, Kaida A, Matsuya Y, Uo M, Yoshimura RI, Arazi L, Miura M. DNA damage response in a 2D-culture model by diffusing alpha-emitters radiation therapy (Alpha-DaRT). Sci Rep 2024; 14:11468. [PMID: 38769339 PMCID: PMC11106084 DOI: 10.1038/s41598-024-62071-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2023] [Accepted: 05/13/2024] [Indexed: 05/22/2024] Open
Abstract
Diffusing alpha-emitters radiation therapy (Alpha-DaRT) is a unique method, in which interstitial sources carrying 224Ra release a chain of short-lived daughter atoms from their surface. Although DNA damage response (DDR) is crucial to inducing cell death after irradiation, how the DDR occurs during Alpha-DaRT treatment has not yet been explored. In this study, we temporo-spatially characterized DDR such as kinetics of DNA double-strand breaks (DSBs) and cell cycle, in two-dimensional (2D) culture conditions qualitatively mimicking Alpha-DaRT treatments, by employing HeLa cells expressing the Fucci cell cycle-visualizing system. The distribution of the alpha-particle pits detected by a plastic nuclear track detector, CR-39, strongly correlated with γH2AX staining, a marker of DSBs, around the 224Ra source, but the area of G2 arrested cells was more widely spread 24 h from the start of the exposure. Thereafter, close time-lapse observation revealed varying cell cycle kinetics, depending on the distance from the source. A medium containing daughter nuclides prepared from 224Ra sources allowed us to estimate the radiation dose after 24 h of exposure, and determine surviving fractions. The present experimental model revealed for the first time temporo-spatial information of DDR occurring around the source in its early stages.
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Affiliation(s)
- Hitomi Nojima
- Department of Dental Radiology and Radiation Oncology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8549, Japan
| | - Atsushi Kaida
- Department of Dental Radiology and Radiation Oncology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8549, Japan
| | - Yusuke Matsuya
- Nuclear Science and Engineering Center, Japan Atomic Energy Agency, 2-4 Shirakata, Tokai, Ibaraki, 319-1195, Japan
- Faculty of Health Sciences, Hokkaido University, Kita-12 Nishi-5, Kita-ku, Sapporo, Hokkaido, 060-0812, Japan
| | - Motohiro Uo
- Department of Advanced Biomaterials, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8549, Japan
| | - Ryo-Ichi Yoshimura
- Department of Radiation Therapeutics and Oncology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8549, Japan
| | - Lior Arazi
- Unit of Nuclear Engineering, Faculty of Engineering Sciences, Ben-Gurion University of the Negev, P.O.B. 653, 8410501, Be'er-Sheva, Israel
| | - Masahiko Miura
- Department of Dental Radiology and Radiation Oncology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8549, Japan.
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Epstein L, Heger G, Roy A, Gannot I, Kelson I, Arazi L. The low-LET radiation contribution to the tumor dose in diffusing alpha-emitters radiation therapy. Med Phys 2024; 51:3020-3033. [PMID: 38096442 DOI: 10.1002/mp.16885] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2023] [Revised: 11/16/2023] [Accepted: 11/21/2023] [Indexed: 04/05/2024] Open
Abstract
BACKGROUND Diffusing alpha-emitters Radiation Therapy ("Alpha DaRT") is a new technique that enables the use of alpha particles for the treatment of solid tumors. Alpha DaRT employs interstitial sources carrying a few μ $\mu$ Ci of224 $^{224}$ Ra below their surface, designed to release a chain of short-lived atoms (progeny of224 $^{224}$ Ra) which emit alpha particles, along with beta, Auger, and conversion electrons, x- and gamma rays. These atoms diffuse around the source and create-primarily through their alpha decays-a lethal high-dose region measuring a few millimeters in diameter. PURPOSE While previous studies focused on the dose from the alpha emissions alone, this work addresses the electron and photon dose contributed by the diffusing atoms and by the atoms remaining on the source surface, for both a single Alpha DaRT source and multi-source lattices. This allows to evaluate the low-LET contribution to the tumor dose and tumor cell survival, and demonstrate the sparing of surrounding healthy tissue. METHODS The low-LET dose is calculated using the EGSnrc and FLUKA Monte Carlo (MC) codes. We compare the results of a simple line-source approximation with no diffusion to those of a full simulation, which implements a realistic source geometry and the spread of diffusing atoms. We consider two opposite scenarios: one with low diffusion and high212 $^{212}$ Pb leakage, and the other with high diffusion and low leakage. The low-LET dose in source lattices is calculated by superposition of single-source contributions. Its effect on cell survival is estimated with the linear quadratic model in the limit of low dose rate. RESULTS For sources carrying 3 μ $\umu$ Ci/cm224 $^{224}$ Ra arranged in a hexagonal lattice with 4 mm spacing, the minimal low-LET dose between sources is∼ 18 - 30 $\sim 18-30$ Gy for the two test cases and is dominated by the beta contribution. The low-LET dose drops below 5 Gy∼ 3 $\sim 3$ mm away from the outermost source in the lattice with an effective maximal dose rate of< 0.04 $<0.04$ Gy/h. The accuracy of the line-source/no-diffusion approximation is∼ 15 % $\sim 15\%$ for the total low-LET dose over clinically relevant distances (2-4 mm). The low-LET dose reduces tumor cell survival by a factor of∼ 2 - 200 $\sim 2-200$ . CONCLUSIONS The low-LET dose in Alpha DaRT can be modeled by conventional MC techniques with appropriate leakage corrections to the source activity. For 3 μ $\umu$ Ci/cm224 $^{224}$ Ra sources, the contribution of the low-LET dose can reduce cell survival inside the tumor by up to two orders of magnitude. The low-LET dose to surrounding healthy tissue is negligible. Increasing source activities by a factor of 5 can bring the low-LET dose itself to therapeutic levels, in addition to the high-LET dose contributed by alpha particles, leading to a "self-boosted" Alpha DaRT configuration, and potentially allowing to increase the lattice spacing.
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Affiliation(s)
- Lior Epstein
- Unit of Nuclear Engineering, Faculty of Engineering Sciences, Ben-Gurion University of the Negev, Be'er-Sheva, Israel
- Department of Biomedical Engineering, Faculty of Engineering, Tel Aviv University, Tel Aviv, Israel
- Soreq Nuclear Research Center, Yavne, Israel
| | - Guy Heger
- Unit of Nuclear Engineering, Faculty of Engineering Sciences, Ben-Gurion University of the Negev, Be'er-Sheva, Israel
| | - Arindam Roy
- Unit of Nuclear Engineering, Faculty of Engineering Sciences, Ben-Gurion University of the Negev, Be'er-Sheva, Israel
| | - Israel Gannot
- Department of Biomedical Engineering, Faculty of Engineering, Tel Aviv University, Tel Aviv, Israel
| | - Itzhak Kelson
- School of Physics and Astronomy, Faculty of Exact Sciences, Tel Aviv University, Tel Aviv, Israel
| | - Lior Arazi
- Unit of Nuclear Engineering, Faculty of Engineering Sciences, Ben-Gurion University of the Negev, Be'er-Sheva, Israel
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Zhou L, Liu Y, Wu Y, Yang X, Spring Kong FM, Lu Y, Xue J. Low-dose radiation therapy mobilizes antitumor immunity: New findings and future perspectives. Int J Cancer 2024; 154:1143-1157. [PMID: 38059788 DOI: 10.1002/ijc.34801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Revised: 10/24/2023] [Accepted: 10/31/2023] [Indexed: 12/08/2023]
Abstract
Radiotherapy has unique immunostimulatory and immunosuppressive effects. Although high-dose radiotherapy has been found to have systemic antitumor effects, clinically significant abscopal effects were uncommon on the basis of irradiating single lesion. Low-dose radiation therapy (LDRT) emerges as a novel approach to enhance the antitumor immune response due to its role as a leverage to reshape the tumor immune microenvironment (TIME). In this article, from bench to bedside, we reviewed the possible immunomodulatory role of LDRT on TIME and systemic tumor immune environment, and outlined preclinical evidence and clinical application. We also discussed the current challenges when LDRT is used as a combination therapy, including the optimal dose, fraction, frequency, and combination of drugs. The advantage of low toxicity makes LDRT potential to be applied in multiple lesions to amplify antitumor immune response in polymetastatic disease, and its intersection with other disciplines might also make it a direction for radiotherapy-combined modalities.
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Affiliation(s)
- Laiyan Zhou
- Division of Thoracic Tumor Multimodality Treatment, Cancer Center, West China Hospital, Sichuan University, Chengdu, China
- Disaster Medical Center, Sichuan University, Chengdu, China
| | - Yuanxin Liu
- Division of Thoracic Tumor Multimodality Treatment, Cancer Center, West China Hospital, Sichuan University, Chengdu, China
| | - Yuanjun Wu
- Division of Thoracic Tumor Multimodality Treatment, Cancer Center, West China Hospital, Sichuan University, Chengdu, China
| | - Xue Yang
- Division of Thoracic Tumor Multimodality Treatment, Cancer Center, West China Hospital, Sichuan University, Chengdu, China
| | - Feng-Ming Spring Kong
- Department of Clinical Oncology, The University of Hong Kong-Shenzhen Hospital, Shenzhen, China
- Department of Clinical Oncology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
| | - You Lu
- Division of Thoracic Tumor Multimodality Treatment, Cancer Center, West China Hospital, Sichuan University, Chengdu, China
- Department of Radiation Oncology, Cancer Center, West China Hospital, Sichuan University, Chengdu, China
- Laboratory of Clinical Cell Therapy, West China Hospital, Sichuan University, Chengdu, China
| | - Jianxin Xue
- Division of Thoracic Tumor Multimodality Treatment, Cancer Center, West China Hospital, Sichuan University, Chengdu, China
- Department of Radiation Oncology, Cancer Center, West China Hospital, Sichuan University, Chengdu, China
- Laboratory of Clinical Cell Therapy, West China Hospital, Sichuan University, Chengdu, China
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Fedorchenko D, Alani S. Simulation of particle release for Diffusing Alpha-Emitters Radiation Therapy. Appl Radiat Isot 2023; 197:110825. [PMID: 37099829 DOI: 10.1016/j.apradiso.2023.110825] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2022] [Revised: 04/09/2023] [Accepted: 04/13/2023] [Indexed: 04/28/2023]
Abstract
We used Monte Carlo simulations to study release of 224Ra daughter nuclei from the seed used for Diffusing Alpha-Emitters Radiation Therapy (DART). Calculated desorption probabilities for 216Po (15%) and 212Pb (12%) showed that they make a significant contribution to total release from the seed. We also showed that the dose to tissue from decays inside the 10 mm long seed exceeds 2.9 Gy for initial 224Ra activity of 3 μCi (111 kBq).
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Affiliation(s)
| | - Shlomi Alani
- Ziv Medical Center, Derech HaRambam, Zefat, 13100, Israel.
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Heger G, Roy A, Dumančić M, Arazi L. Alpha dose modeling in diffusing alpha-emitters radiation therapy-Part I: single-seed calculations in one and two dimensions. Med Phys 2023; 50:1793-1811. [PMID: 36464914 DOI: 10.1002/mp.16145] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2021] [Revised: 09/01/2022] [Accepted: 09/29/2022] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND Diffusing alpha-emitters Radiation Therapy ("DaRT") is a new method, presently in clinical trials, which allows treating solid tumors by alpha particles. DaRT relies on interstitial seeds carrying μCi-level 224 Ra activity below their surface, which release a chain of short-lived alpha emitters that spread throughout the tumor volume primarily by diffusion. Alpha dose calculations in DaRT are based on describing the transport of alpha emitting atoms, requiring new modeling techniques. PURPOSE A previous study introduced a simplified framework, the "Diffusion-Leakage (DL) model", for DaRT alpha dose calculations, and employed it to a point source, as a basic building block of arbitrary configurations of line sources. The aim of this work, which is divided into two parts, is to extend the model to realistic seed geometries (in Part I), and to employ single-seed calculations to study the properties of DaRT seed lattices (Part II). Such calculations can serve as a pragmatic guide for treatment planning in future clinical trials. METHODS We derive a closed-form asymptotic solution for an infinitely long cylindrical source, and extend it to an approximate time-dependent expression that assumes a uniform temporal profile at all radial distances from the source. We then develop a finite-element one-dimensional numerical scheme for a complete time-dependent solution of this geometry and validate it against the closed-form expressions. Finally, we discuss a two-dimensional axisymmetric scheme for a complete time-dependent solution for a seed of finite diameter and length. Different solutions are compared over the relevant parameter space, providing guidelines on their usability and limitations. RESULTS We show that approximating the seed as a finite line source comprised of point-like segments significantly underestimates the correct alpha dose, as predicted by the full two-dimensional calculation. The time-dependent one-dimensional solution is shown to coincide to sub-percent-level with the two-dimensional calculation in the seed midplane, and maintains an accuracy of a few percent up to ∼2 mm from the seed edge. CONCLUSIONS For actual treatment plans, the full two-dimensional solution should be used to generate dose lookup tables, similarly to the TG-43 format employed in conventional brachytherapy. Given the accuracy of the one-dimensional solution up to ∼2 mm from the seed edge it can be used for efficient parametric studies of DaRT seed lattices.
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Affiliation(s)
- Guy Heger
- Unit of Nuclear Engineering, Faculty of Engineering Sciences, Ben-Gurion University of the Negev, Be'er-Sheva, Israel
| | - Arindam Roy
- Unit of Nuclear Engineering, Faculty of Engineering Sciences, Ben-Gurion University of the Negev, Be'er-Sheva, Israel
| | - Mirta Dumančić
- Unit of Nuclear Engineering, Faculty of Engineering Sciences, Ben-Gurion University of the Negev, Be'er-Sheva, Israel
| | - Lior Arazi
- Unit of Nuclear Engineering, Faculty of Engineering Sciences, Ben-Gurion University of the Negev, Be'er-Sheva, Israel
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