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Kampfer S, Dobiasch S, Combs SE, Wilkens JJ. Development of a PTV margin for preclinical irradiation of orthotopic pancreatic tumors derived from a well-known recipe for humans. Z Med Phys 2023:S0939-3889(23)00042-9. [PMID: 37225604 DOI: 10.1016/j.zemedi.2023.03.005] [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: 12/19/2022] [Revised: 03/27/2023] [Accepted: 03/30/2023] [Indexed: 05/26/2023]
Abstract
In human radiotherapy a safety margin (PTV margin) is essential for successful irradiation and is usually part of clinical treatment planning. In preclinical radiotherapy research with small animals, most uncertainties and inaccuracies are present as well, but according to the literature a margin is used only scarcely. In addition, there is only little experience about the appropriate size of the margin, which should carefully be investigated and considered, since sparing of organs at risk or normal tissue is affected. Here we estimate the needed margin for preclinical irradiation by adapting a well-known human margin recipe from van Herck et al. to the dimensions and requirements of the specimen on a small animal radiation research platform (SARRP). We adjusted the factors of the described formula to the specific challenges in an orthotopic pancreatic tumor mouse model to establish an appropriate margin concept. The SARRP was used with its image-guidance irradiation possibility for arc irradiation with a field size of 10 × 10 mm2 for 5 fractions. Our goal was to irradiate the clinical target volume (CTV) of at least 90% of our mice with at least 95% of the prescribed dose. By carefully analyzing all relevant factors we gain a CTV to planning target volume (PTV) margin of 1.5 mm for our preclinical setup. The stated safety margin is strongly dependent on the exact setting of the experiment and has to be adjusted for other experimental settings. The few stated values in literature correspond well to our result. Even if using margins in the preclinical setting might be an additional challenge, we think it is crucial to use them to produce reliable results and improve the efficacy of radiotherapy.
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Affiliation(s)
- Severin Kampfer
- Department of Radiation Oncology, School of Medicine and Klinikum rechts der Isar, Technical University of Munich (TUM), Munich, Germany; Physics Department, Technical University of Munich (TUM), Garching, Germany.
| | - Sophie Dobiasch
- Department of Radiation Oncology, School of Medicine and Klinikum rechts der Isar, Technical University of Munich (TUM), Munich, Germany; Institute of Radiation Medicine (IRM), Department of Radiation Sciences (DRS), Helmholtz Zentrum München, Neuherberg, Germany.
| | - Stephanie E Combs
- Department of Radiation Oncology, School of Medicine and Klinikum rechts der Isar, Technical University of Munich (TUM), Munich, Germany; Institute of Radiation Medicine (IRM), Department of Radiation Sciences (DRS), Helmholtz Zentrum München, Neuherberg, Germany; German Cancer Consortium (DKTK), Partner Site Munich, Germany.
| | - Jan J Wilkens
- Department of Radiation Oncology, School of Medicine and Klinikum rechts der Isar, Technical University of Munich (TUM), Munich, Germany; Physics Department, Technical University of Munich (TUM), Garching, Germany; Institute of Radiation Medicine (IRM), Department of Radiation Sciences (DRS), Helmholtz Zentrum München, Neuherberg, Germany.
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2
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Kampfer S, Dobiasch S, Combs SE, Wilkens JJ. Comparison of 3 Positioning Techniques for Fractionated High-precision Radiotherapy in an Orthotopic Mouse Model of Pancreatic Cancer. Comp Med 2022; 72:336-341. [PMID: 36127130 PMCID: PMC9827594 DOI: 10.30802/aalas-cm-22-000060] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Small-animal irradiators are widely used in oncologic research, and many experiments use mice to mimic radiation treatments in humans. To improve fractionated high-precision irradiation in mice with orthotopic pancreatic tumors, we evaluated 3 positioning methods: no positioning aid, skin marker, and immobilization devices (immobilization masks). We retrospectively evaluated the translation vector needed for optimal tumor alignment (by shifting the mouse in left-right, in cranio-caudal, and in anterior-posterior direction) on cone-beam CT from our small-animal radiotherapy system. Of the 3 methods, the skin marker method yielded the smallest mean translation vector (3.8 mm) and was the most precise method overall for most of the mice. In addition, the skin marker method required supplemental rotation (that is, roll, pitch, and yaw) for optimal tumor alignment only half as often as positioning without a positioning aid. Finally, the skin marker method had the highest scores for the quality of the fusion results. Overall, we preferred the skin marker method over the other 2 positioning methods with regard to optimal treatment planning and radiotherapy in an orthotopic mouse model of pancreatic cancer.
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Affiliation(s)
- Severin Kampfer
- Department of Radiation Oncology, School of Medicine and Klinikum rechts der Isar, Technical University of Munich (TUM), Munich, Germany and,Physics Department, Technical University of Munich (TUM), Garching, Germany;,Corresponding author:
| | - Sophie Dobiasch
- Department of Radiation Oncology, School of Medicine and Klinikum rechts der Isar, Technical University of Munich (TUM), Munich, Germany and,Department of Radiation Sciences (DRS), Institute of Radiation Medicine (IRM), Helmholtz Zentrum München - German Research Center for Environmental Health, Neuherberg, Germany; and
| | - Stephanie E Combs
- Department of Radiation Oncology, School of Medicine and Klinikum rechts der Isar, Technical University of Munich (TUM), Munich, Germany and,Department of Radiation Sciences (DRS), Institute of Radiation Medicine (IRM), Helmholtz Zentrum München - German Research Center for Environmental Health, Neuherberg, Germany; and,German Cancer Consortium (DKTK), Munich, Germany
| | - Jan J Wilkens
- Department of Radiation Oncology, School of Medicine and Klinikum rechts der Isar, Technical University of Munich (TUM), Munich, Germany and,Physics Department, Technical University of Munich (TUM), Garching, Germany
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3
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Aalam SMM, Viringipurampeer IA, Walb MC, Tryggestad EJ, Emperumal CP, Song J, Xu X, Saini R, Lombaert IMA, Sarkaria JN, Garcia J, Janus JR, Kannan N. Characterization of Transgenic NSG-SGM3 Mouse Model of Precision Radiation-Induced Chronic Hyposalivation. Radiat Res 2022; 198:243-254. [PMID: 35820185 DOI: 10.1667/rade-21-00237.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Accepted: 06/06/2022] [Indexed: 11/03/2022]
Abstract
Regenerative medicine holds promise to cure radiation-induced salivary hypofunction, a chronic side effect in patients with head and neck cancers, therefore reliable preclinical models for salivary regenerative outcome will promote progress towards therapies. In this study, our objective was to develop a cone beam computed tomography-guided precision ionizing radiation-induced preclinical model of chronic hyposalivation using immunodeficient NSG-SGM3 mice. Using a Schirmer's test based sialagogue-stimulated saliva flow kinetic measurement method, we demonstrated significant differences in hyposalivation specific to age, sex, precision-radiation dose over a chronic (6 months) timeline. NSG-SMG3 mice tolerated doses from 2.5 Gy up to 7.5 Gy. Interestingly, 5-7.5 Gy had similar effects on stimulated-saliva flow (∼50% reduction in young female at 6 months after precision irradiation over sham-treated controls), however, >5 Gy led to chronic alopecia. Different groups demonstrated characteristic saliva fluctuations early on, but after 5 months all groups nearly stabilized stimulated-saliva flow with low-inter-mouse variation within each group. Further characterization revealed precision-radiation-induced glandular shrinkage, hypocellularization, gland-specific loss of functional acinar and glandular cells in all major salivary glands replicating features of human salivary hypofunction. This model will aid investigation of human cell-based salivary regenerative therapies.
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Affiliation(s)
| | | | - Matthew C Walb
- Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota
| | | | - Chitra P Emperumal
- Department of Otolaryngology-Head and Neck Surgery, Mayo Clinic, Rochester, Minnesota
| | - Jianning Song
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota
| | - Xuewen Xu
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota
| | - Rajan Saini
- Department of Oral Biological and Medical Sciences, Faculty of Dentistry, University of British Columbia, Vancouver, British Columbia, Canada
| | - Isabelle M A Lombaert
- Biointerfaces Institute, School of Dentistry, Department of Biologic and Materials Sciences, University of Michigan, Ann Arbor, Michigan
| | - Jann N Sarkaria
- Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota
| | - Joaquin Garcia
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota
| | - Jeffrey R Janus
- Department of Otolaryngology-Head and Neck Surgery, Mayo Clinic, Rochester, Minnesota.,Department of Otolaryngology-Head and Neck Surgery, Mayo Clinic, Jacksonville, Florida.,Center for Regenerative Medicine, Mayo Clinic, Rochester, Minnesota
| | - Nagarajan Kannan
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota.,Center for Regenerative Medicine, Mayo Clinic, Rochester, Minnesota.,Mayo Clinic Cancer Center, Mayo Clinic, Rochester, Minnesota
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4
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Dragojevic S, Ji J, Singh PK, Connors MA, Mutter RW, Lester SC, Talele SM, Zhang W, Carlson BL, Remmes NB, Park SS, Elmquist WF, Krishnan S, Tryggestad EJ, Sarkaria JN. Preclinical Risk Evaluation of Normal Tissue Injury With Novel Radiosensitizers. Int J Radiat Oncol Biol Phys 2021; 111:e54-e62. [PMID: 34400266 PMCID: PMC8764622 DOI: 10.1016/j.ijrobp.2021.08.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Revised: 08/03/2021] [Accepted: 08/04/2021] [Indexed: 12/14/2022]
Abstract
Genotoxic damage induced by radiation triggers a highly coordinated DNA damage response, and molecular inhibitors of key nodes within this complex response network can profoundly enhance the antitumor efficacy of radiation. This is especially true for drugs targeting the catalytic subunit of DNA-dependent protein kinase, which is a core component of the nonhomologous end-joining DNA repair pathway, and ataxia telangiectasia mutated, which coordinates cell cycle arrest, apoptosis, and DNA repair functionalities after radiation exposure. Unlike the more modest in vitro radiosensitizing effects seen with classic sensitizing agents such as cisplatin, 5-fluorouracil, or taxanes, DNA-dependent protein kinase or ataxia telangiectasia mutated inhibitors provide much more robust sensitizing effects in vitro, as might be anticipated from targeting these key DNA repair modulators. However, patients with homozygous inactivating mutations of ataxia telangiectasia mutated or mice with homozygous defects in DNA-dependent protein kinase (severe combined immunodeficiency) have profoundly enhanced acute normal tissue radiation reactions. Therefore, there is significant potential that the combination of small molecule inhibitors of these kinases with radiation could cause similar dose-limiting acute normal tissue toxicities. Similarly, although less understood, inhibition of these DNA repair response pathways could markedly increase the risk of late radiation toxicities. Because these potent radiosensitizers could be highly useful to improve local control of otherwise radiation-resistant tumors, understanding the potential for elevated risks of radiation injury is essential for optimizing therapeutic ratio and developing safe and informative clinical trials. In this review, we will discuss 2 straightforward models to assess the potential for enhanced mucosal toxicity in the oral cavity and small intestine established in our laboratories. We also will discuss similar strategies for evaluating potential drug-radiation interactions with regard to increased risks of debilitating late effects.
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Affiliation(s)
- Sonja Dragojevic
- Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota
| | - Jianxiong Ji
- Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota,Department of Neurosurgery, Qilu Hospital and Institute of Brain and Brain-Inspired Science, Cheeloo College of Medicine, Shandong University, Jinan, China,Department of Neurosurgery, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Pankaj K. Singh
- Department of Radiation Oncology, Mayo Clinic Florida, Jacksonville, Florida
| | | | - Robert W. Mutter
- Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota
| | - Scott C. Lester
- Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota
| | - Surabhi M. Talele
- Department of Pharmaceutics, University of Minnesota, Minneapolis, Minnesota
| | - Wenjuan Zhang
- Department of Pharmaceutics, University of Minnesota, Minneapolis, Minnesota
| | - Brett L. Carlson
- Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota
| | | | - Sean S. Park
- Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota
| | - William F. Elmquist
- Department of Pharmaceutics, University of Minnesota, Minneapolis, Minnesota
| | - Sunil Krishnan
- Department of Radiation Oncology, Mayo Clinic Florida, Jacksonville, Florida
| | | | - Jann N. Sarkaria
- Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota
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5
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Rajani K, Olson I, Jacobs JJ, Riviere-Cazaux C, Burns K, Carlstrom L, Schroeder M, Oh J, Howe CL, Rahman M, Sarkaria JN, Elmquist WF, Burns TC. Methods for intratumoral microdialysis probe targeting and validation in murine brain tumor models. J Neurosci Methods 2021; 363:109321. [PMID: 34390758 PMCID: PMC10703144 DOI: 10.1016/j.jneumeth.2021.109321] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Revised: 06/27/2021] [Accepted: 08/09/2021] [Indexed: 11/22/2022]
Abstract
BACKGROUND Microdialysis is a well validated sampling technique that can be used for pharmacokinetic studies of oncological drugs targeting the central nervous system. This technique has also been applied to evaluate tumor metabolism and identify pharmacodynamic biomarkers of drug activity. Despite the potential utility of microdialysis for therapeutic discovery, variability in tumor size and location hamper routine use of microdialysis as a preclinical tool. Quantitative validation of microdialysis membrane location relative to radiographically evident tumor regions could facilitate rigorous preclinical studies. However, a widely accessible standardized workflow for preclinical catheter placement and validation is needed. NEW METHOD We provide methods for a workflow to yield tailored placement of microdialysis probes within a murine intracranial tumor and illustrate in an IDH1-mutant patient-derived xenograft (PDX) model. This detailed workflow uses a freely available on-line tool built within 3D-slicer freeware to target microdialysis probe placement within the tumor core and validate probe placement fully within the tumor. RESULTS We illustrate use of this workflow to validate microdialysis probe location relative to implanted IDH1-mutant PDXs, using the microdialysis probes to quantify levels of extracellular onco-metabolite D-2 hydroxyglutarate. COMPARISON WITH EXISTING METHODS Previous methods have used 3D slicer to reliably measure tumor volumes. Prior microdialysis studies have targeted expected tumor locations without validation. CONCLUSIONS The new method offers a streamlined and freely available workflow in 3D slicer to optimize and validate microdialysis probe placement within a murine brain tumor.
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Affiliation(s)
- Karishma Rajani
- Department of Neurologic Surgery, Mayo Clinic, Rochester, MN, United States
| | - Ian Olson
- Department of Neurologic Surgery, Mayo Clinic, Rochester, MN, United States
| | - Joshua J Jacobs
- Department of Neurologic Surgery, Mayo Clinic, Rochester, MN, United States
| | | | - Kirsten Burns
- Department of Neurologic Surgery, Mayo Clinic, Rochester, MN, United States
| | - Lucas Carlstrom
- Department of Neurologic Surgery, Mayo Clinic, Rochester, MN, United States
| | - Mark Schroeder
- Department of Neurologic Surgery, Mayo Clinic, Rochester, MN, United States
| | - Juhee Oh
- Brain Barriers Research Center, Department of Pharmaceutics, College of Pharmacy, University of Minnesota, Minneapolis, United States
| | - Charles L Howe
- Department of Neurology, Mayo Clinic, Rochester, MN, United States
| | - Masum Rahman
- Department of Neurologic Surgery, Mayo Clinic, Rochester, MN, United States; Brain Barriers Research Center, Department of Pharmaceutics, College of Pharmacy, University of Minnesota, Minneapolis, United States; Department of Neurology, Mayo Clinic, Rochester, MN, United States; Department of Radiation Oncology, Mayo Clinic, Rochester, MN, United States
| | - Jann N Sarkaria
- Department of Radiation Oncology, Mayo Clinic, Rochester, MN, United States
| | - William F Elmquist
- Brain Barriers Research Center, Department of Pharmaceutics, College of Pharmacy, University of Minnesota, Minneapolis, United States
| | - Terry C Burns
- Department of Neurologic Surgery, Mayo Clinic, Rochester, MN, United States.
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6
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Buchsbaum JC, Coleman CN, Bernhard EJ, Espey MG, Vikram B. Overview and Lessons From the Preclinical Chemoradiotherapy Testing Consortium. Int J Radiat Oncol Biol Phys 2021; 111:1126-1130. [PMID: 34348172 DOI: 10.1016/j.ijrobp.2021.07.1709] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Accepted: 07/22/2021] [Indexed: 11/16/2022]
Abstract
PURPOSE In the current molecular-targeted cancer treatment era, many new agents are being developed so that optimizing therapy with a combination of radiation and drugs is complex. The use of emerging laboratory technologies to further biological understanding of drug-radiation mechanisms of action will enhance the efficiency of the progression from preclinical studies to clinical trials. In 2017, the National Cancer Institute (NCI) solicited proposals through PAR 16-111 to conduct preclinical research combining targeted anticancer agents in the Cancer Therapy Evaluation Program's portfolio with chemoradiation. METHODS AND MATERIALS The Preclinical Chemo-Radiotherapy Testing Consortium (PCRTC) was formed with 4 U01 programs supported to generate validated high-quality preclinical data on the effects of molecular therapeutics when added to standard-of-care therapies with a concentration on cancers of the pancreas, lung, head and neck, gastrointestinal tract, and brain. RESULTS The PCRTC provides a rational basis for prioritizing NCI-supported investigational new drugs or agents most likely to have clinical activity with chemoradiotherapy and accelerate the pace at which combined modality treatments with greater efficacy are identified and incorporated into standard treatment practices. CONCLUSIONS Herein, we introduce and summarize the course of the PCRTC to date and report 3 preliminary observations from the consortium's work to date.
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Affiliation(s)
- Jeffrey C Buchsbaum
- Radiation Research Program, Division of Cancer Treatment and Diagnosis, National Cancer Institute, National Institutes of Health, Bethesda, Maryland.
| | - C Norman Coleman
- Radiation Research Program, Division of Cancer Treatment and Diagnosis, National Cancer Institute, National Institutes of Health, Bethesda, Maryland
| | - Eric J Bernhard
- Radiation Research Program, Division of Cancer Treatment and Diagnosis, National Cancer Institute, National Institutes of Health, Bethesda, Maryland
| | - Michael G Espey
- Radiation Research Program, Division of Cancer Treatment and Diagnosis, National Cancer Institute, National Institutes of Health, Bethesda, Maryland
| | - Bhadrasain Vikram
- Radiation Research Program, Division of Cancer Treatment and Diagnosis, National Cancer Institute, National Institutes of Health, Bethesda, Maryland
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7
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Müller J, Schürer M, Neubert C, Tillner F, Beyreuther E, Suckert T, Peters N, von Neubeck C, Lühr A, Krause M, Bütof R, Dietrich A. Multi-modality bedding platform for combined imaging and irradiation of mice. Biomed Phys Eng Express 2020; 6:037003. [PMID: 33438682 DOI: 10.1088/2057-1976/ab79f1] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Preclinical imaging and irradiation yields valuable insights into clinically relevant research topics. While complementary imaging methods such as computed tomography (CT), magnetic resonance imaging (MRI), and positron emission tomography (PET) can be combined within single devices, this is technically demanding and cost-intensive. Similarly, bedding and setup solutions are often specific to certain devices and research questions. We present a bedding platform for mice that is compatible with various preclinical imaging modalities (combined PET/MRI, cone beam CT) and irradiation with photons and protons. It consists of a 3D-printed bedding unit (acrylonitrile butadiene styrene, ABS) holding the animal and features an inhalation anesthesia mask, jaw fixation, ear pins, and immobilization for the hind leg. It can be embedded on mounting adaptors for multi-modal imaging and into a transport box (polymethyl methacrylate, PMMA) for experiments outside dedicated animal facilities while maintaining the animal's hygiene status. A vital support unit provides heating, inhalation anesthesia, and a respiration monitor. We dosimetrically evaluated used materials in order to assess their interaction with incident irradiation. Proof-of-concept multi-modal imaging protocols were used on phantoms and mice. The measured attenuation of the bedding unit for 40/60/80/200 kV X-rays was less than 3%. The measured stopping-power-ratio of ABS was 0.951, the combined water-equivalent thickness of bedding unit and transport box was 4.2 mm for proton energies of 150 MeV and 200 MeV. Proof-of-concept imaging showed no loss of image quality. Imaging data of individual mice from different imaging modalities could be aligned rigidly. The presented bed aims to provide a platform for experiments related to both multi-modal imaging and irradiation, thus offering the possibility for image-guided irradiation which relies on precise imaging and positioning. The usage as a self-contained, stand-alone unit outside dedicated animal facilities represents an advantage over setups designed for specific devices.
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Affiliation(s)
- Johannes Müller
- OncoRay-National Center for Radiation Research in Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden, Helmholtz-Zentrum Dresden - Rossendorf, Dresden, Germany. Helmholtz-Zentrum Dresden - Rossendorf, Dresden, Institute of Radiooncology-OncoRay, Germany
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8
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Smith EJ, Tryggestad EJ, Carlson BL, Walb MC, Sarkaria JN. Imaging and Dosimetry Study of Inter-fraction Setup Error in a Murine Xenograft Flank Tumor Radiation Model. Radiat Res 2019; 193:161-170. [PMID: 31877254 DOI: 10.1667/rr15526.1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Modern small animal irradiation platforms provide for accurate delivery of radiation under 3D image guidance. However, leveraging these improvements currently comes at the cost of lower-throughput experimentation. Herein, we characterized setup accuracy and dosimetric robustness for mock/sham irradiation of a murine xenograft flank tumor model using the X-RAD SmART+ with the vendor-supplied Monte Carlo (MC) treatment planning system (SmART ATP). The chosen beam arrangement was parallel-opposing using a 20 mm square collimator, aligned off-axis for ipsilateral lung sparing. Using a cohort of five mice imaged with cone beam computed tomography (CBCT) over five consecutive mock-irradiation fractions, we compared inter-fraction setup variability resulting from a vendor-supplied multi-purpose bed with anesthesia nose cone with a more complicated immobilization solution with an integrated bite block with nose cone and Styrofoam platform. A hypothetical "high-throughput" image-guidance scenario was investigated, wherein the day 1 stage coordinates (resulting from CBCT guidance) were applied on days 2-5. Daily inter-fraction setup errors were evaluated per specimen (days 2-5) using CBCT-derived offsets from day 1 stage coordinates. Using the CBCT images and Monte Carlo dose calculation, 3D dosimetric plan robustness was evaluated for the vendor-supplied immobilization solution, for both the high-throughput guidance scenario as well as for use of daily CBCT-based alignment. Inter-fraction setup offset magnitude was 3.6 (±1.5) mm for the vendor-supplied immobilization compared to 3.3 (±1.8) mm for the more complicated solution. For the vendor-supplied immobilization, we found that daily CBCT was needed to adequately cover the flank tumors dosimetrically, given our chosen treatment approach.
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Affiliation(s)
- Emily J Smith
- Department of Radiation Oncology, Mayo Clinic Rochester, Rochester, Minnesota 55905
| | - Erik J Tryggestad
- Department of Radiation Oncology, Mayo Clinic Rochester, Rochester, Minnesota 55905
| | - Brett L Carlson
- Department of Radiation Oncology, Mayo Clinic Rochester, Rochester, Minnesota 55905
| | - Matthew C Walb
- Department of Radiation Oncology, Mayo Clinic Rochester, Rochester, Minnesota 55905
| | - Jann N Sarkaria
- Department of Radiation Oncology, Mayo Clinic Rochester, Rochester, Minnesota 55905
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