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Dean J, Anderson N, Halkett GKB, Lye J, Tacey M, Foroudi F, Chao M, Wright C. Study protocol: Optimising patient positioning for the planning of accelerated partial breast radiotherapy for the integrated magnetic resonance linear accelerator: OPRAH MRL. Radiat Oncol 2024; 19:123. [PMID: 39289753 PMCID: PMC11409614 DOI: 10.1186/s13014-024-02517-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2024] [Accepted: 09/04/2024] [Indexed: 09/19/2024] Open
Abstract
BACKGROUND Accelerated partial breast irradiation (APBI) is an accepted treatment option for early breast cancer. Treatment delivered on the Magnetic Resonance integrated Linear Accelerator (MRL) provides the added assurance of improved soft tissue visibility, important in the delivery of APBI. This technique can be delivered in both the supine and prone positions, however current literature suggests that prone treatment on the MRL is infeasible due to physical limitations with bore size. This study aims to investigate the feasibility of positioning patients on a custom designed prone breast board compared with supine positioning on a personalised vacuum bag. Geometric distortion, the relative position of Organs at Risk (OAR) to the tumour bed and breathing motion (intrafraction motion) will be compared between the supine and prone positions. The study will also investigate the positional impact on dosimetry, patient experience, and position preference. METHODS Up to 30 patients will be recruited over a 12-month period for participation in this Human Research Ethics Committee approved exploratory cohort study. Patients will be scanned on the magnetic resonance imaging (MRI) Simulator in both the supine and prone positions as per current standard of care for APBI simulation. Supine and prone positioning comparisons will all be assessed on de-identified MRI image pairs, acquired using appropriate software. Patient experience will be explored through completion of a short, anonymous electronic survey. Descriptive statistics will be used for reporting of results with categorical, parametric/non-parametric tests applied (data format dependent). Survey results will be interpreted by comparison of percentage frequencies across the Likert scales. Thematic content analysis will be used to interpret qualitative data from the open-ended survey questions. DISCUSSION The results of this study will be used to assess the feasibility of treating patients with APBI in the prone position on a custom designed board on the MRL. It may also be used to assist with identification of patients who would benefit from this position over supine without the need to perform both scans. Patient experience and technical considerations will be utilised to develop a tool to assist in this process. Trial registration Australian New Zealand Clinical Trials Registry (ANZCTR): ACTRN1262400067583. Registered 28th of May 2024. https://www.anzctr.org.au/ACTRN12624000679583.aspx.
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Affiliation(s)
- Jenna Dean
- Radiation Oncology, Olivia Newton John Cancer Wellness and Research Centre, Austin Health, PO Box 5555, Heidelberg, VIC, 3084, Australia.
- Department of Medical Imaging and Radiation Sciences, Faculty of Medicine, Nursing and Health Sciences, Monash University, Wellington Rd, Clayton, VIC, 3800, Australia.
| | - Nigel Anderson
- Radiation Oncology, Olivia Newton John Cancer Wellness and Research Centre, Austin Health, PO Box 5555, Heidelberg, VIC, 3084, Australia
| | - Georgia K B Halkett
- Curtin School of Nursing/Curtin Health Innovation Research Institute, Faculty of Health Sciences, Curtin University, GPO Box U1987, Perth, WA, 6845, Australia
| | - Jessica Lye
- Radiation Oncology, Olivia Newton John Cancer Wellness and Research Centre, Austin Health, PO Box 5555, Heidelberg, VIC, 3084, Australia
- School of Health and Biomedical Science, RMIT University, 124 La Trobe St, Melbourne, VIC, 3000, Australia
| | - Mark Tacey
- Radiation Oncology, Olivia Newton John Cancer Wellness and Research Centre, Austin Health, PO Box 5555, Heidelberg, VIC, 3084, Australia
| | - Farshad Foroudi
- Radiation Oncology, Olivia Newton John Cancer Wellness and Research Centre, Austin Health, PO Box 5555, Heidelberg, VIC, 3084, Australia
| | - Michael Chao
- Radiation Oncology, Olivia Newton John Cancer Wellness and Research Centre, Austin Health, PO Box 5555, Heidelberg, VIC, 3084, Australia
| | - Caroline Wright
- Department of Medical Imaging and Radiation Sciences, Faculty of Medicine, Nursing and Health Sciences, Monash University, Wellington Rd, Clayton, VIC, 3800, Australia
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Steciw S, Fallone BG, Yip E. Dose perturbations at tissue interfaces during parallel linac-MR treatments: The "Lateral Scatter Electron Return Effect" (LS-ERE). Med Phys 2024. [PMID: 39153227 DOI: 10.1002/mp.17363] [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: 04/15/2024] [Revised: 08/05/2024] [Accepted: 08/06/2024] [Indexed: 08/19/2024] Open
Abstract
BACKGROUND Magnetic resonance (MR) imaging devices have been integrated with medical linear accelerators (linac) in radiation therapy. Both perpendicular linac-MR (LMR-B⊥) and parallel (LMR-B∥) systems exist, where due to the MR's magnetic field dose can be perturbed in the patient. Dose perturbations from the electron return effect (ERE) and electron streaming effects (ESEs) are present in LMR-B⊥ systems, where a dose collimating effect has been observed in LMR-B∥ systems . PURPOSE To report on an asymmetric dose perturbation which is present at the interface between two different materials during treatment in parallel linac-MR (LMR-B∥) systems. To the best of our knowledge, these asymmetric dose effects, "Lateral Scattered Electron Return Effect" (LS-ERE) have not been previously reported. METHODS BEAMnrc and EGSnrc Monte Carlo (MC) radiation transport codes were used with the EEMF macro to emulate a 6 FFF beam from the 0.5-T Alberta linac-MR (LMR). Simulations were performed at 0.5 and 1.5 T in several different phantom material-interface combinations and field sizes including from modulated MLC-like fields. MC simulations quantified LS-ERE in patient CT datasets for the head, breast, and lung. LS-ERE cancellation techniques were investigated. LS-ERE asymmetries were quantified by subtracting an antiparallel dose from the parallel dose, dividing by two and normalizing to the global 0-T maximum dose. GafChromic film measurements were made in the 0.5-T Alberta LMR-B∥ system using solid water at the water-air interface to validate MC simulations. ERE was simulated for an emulated LMR-B⊥ system and compared to LMR-B∥ dose perturbations. RESULTS LS-ERE is mostly independent of field size for fields >1 × 1 cm2. For 5 × 5-cm2 fields at 0.5T/1.5T, LS-ERE asymmetries are ≤±6.9%/6.9% at bone-air and ≤±9.0%/7.0% at tissue-air for nonair doses, and ≤±4.1%/5.5% at tissue-lung interfaces. LS-ERE increases as the density gradient increases, where the magnitude and extent of LS-ERE are reduced as field strength increases. For a single 5 × 5-cm2 field at 0.5T/1.5T, the LS-ERE asymmetry is ≤±10.2%/8.5% at the tissue-air sinus interface for head, ≤±4.2%/5.3% at the spine-lung interface for the lung, and ≤±5.7%/4.9% at the skin-air interface for a breast tangent plan at 0.5T/1.5T. POP fields mostly remove LS-ERE asymmetries, with magnetic field reversal during treatment being the most effective method. Skin dose was investigated and compared to 0-T treatments for 0.5T/1.5T LMR-B∥ single field breast and head treatments. Including all dosimetric magnetic field perturbations, a 21%/24% and 22%/22% increase in skin dose to head and breast, respectively, was observed, of which LS-ERE is responsible for approximately 30% of the total. Measured LS-ERE asymmetries and dose enhancements at the water-air interface using GafChromic film were in excellent agreement with MC simulations. ERE in 1.5-T LMR-B⊥ systems are on average 5.5 times larger than total dose perturbations at 0.5 T in LMR-B∥ systems. CONCLUSION LS-ERE is present at the interface between materials and awareness of LS-ERE is crucial for proper TPS evaluation for LMR-B∥ treatments, especially in areas where large tissue density gradients exist.
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Affiliation(s)
- Stephen Steciw
- Medical Physics Division, Department of Oncology, University of Alberta, Edmonton, Alberta, Canada
- Department of Medical Physics, Cross Cancer Institute, Edmonton, Alberta, Canada
| | - Biagio G Fallone
- Medical Physics Division, Department of Oncology, University of Alberta, Edmonton, Alberta, Canada
- Department of Medical Physics, Cross Cancer Institute, Edmonton, Alberta, Canada
| | - Eugene Yip
- Medical Physics Division, Department of Oncology, University of Alberta, Edmonton, Alberta, Canada
- Department of Medical Physics, Cross Cancer Institute, Edmonton, Alberta, Canada
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Patterson E, Powers M, Metcalfe PE, Cutajar D, Oborn BM, Baines JA. Electron streaming dose measurements and calculations on a 1.5 T MR-Linac. J Appl Clin Med Phys 2024; 25:e14370. [PMID: 38661097 PMCID: PMC11244671 DOI: 10.1002/acm2.14370] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Revised: 01/04/2024] [Accepted: 04/08/2024] [Indexed: 04/26/2024] Open
Abstract
PURPOSE To evaluate the accuracy of different dosimeters and the treatment planning system (TPS) for assessing the skin dose due to the electron streaming effect (ESE) on a 1.5 T magnetic resonance (MR)-linac. METHOD Skin dose due to the ESE on an MR-linac (Unity, Elekta) was investigated using a solid water phantom rotated 45° in the x-y plane (IEC61217) and centered at the isocenter. The phantom was irradiated with 1 × 1, 3 × 3, 5 × 5, 10 × 10, and 22 × 22 cm2 fields, gantry at 90°. Out-of-field doses (OFDs) deposited by electron streams generated at the entry and exit surface of the angled phantom were measured on the surface of solid water slabs placed ±20.0 cm from the isocenter along the x-direction. A high-resolution MOSkin™ detector served as a benchmark due to its shallower depth of measurement that matches the International Commission on Radiological Protection (ICRP) recommended depth for skin dose assessment (0.07 mm). MOSkin™ doses were compared to EBT3 film, OSLDs, a diamond detector, and the TPS where the experimental setup was modeled using two separate calculation parameters settings: a 0.1 cm dose grid with 0.2% statistical uncertainty (0.1 cm, 0.2%) and a 0.2 cm dose grid with 3.0% statistical uncertainty (0.2 cm, 3.0%). RESULTS OSLD, film, the 0.1 cm, 0.2%, and 0.2 cm, 3.0% TPS ESE doses, underestimated skin doses measured by the MOSkin™ by as much as -75.3%, -7.0%, -24.7%, and -41.9%, respectively. Film results were most similar to MOSkin™ skin dose measurements. CONCLUSIONS These results show that electron streams can deposit significant doses outside the primary field and that dosimeter choice and TPS calculation settings greatly influence the reported readings. Due to the steep dose gradient of the ESE, EBT3 film remains the choice for accurate skin dose assessment in this challenging environment.
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Affiliation(s)
- Elizabeth Patterson
- Centre for Medical and Radiation PhysicsUniversity of WollongongWollongongNew South WalesAustralia
| | - Marcus Powers
- College of Science and EngineeringJames Cook UniversityTownsvilleQueenslandAustralia
- Townsville Cancer CentreTownsville Hospital and Health ServiceTownsvilleQueenslandAustralia
| | - Peter E. Metcalfe
- Centre for Medical and Radiation PhysicsUniversity of WollongongWollongongNew South WalesAustralia
- Illawarra Health Medical Research InstituteUniversity of WollongongWollongongNew South WalesAustralia
| | - Dean Cutajar
- Centre for Medical and Radiation PhysicsUniversity of WollongongWollongongNew South WalesAustralia
- Department of Radiation OncologySt George Cancer Care CentreWollongongNew South WalesAustralia
| | - Bradley M. Oborn
- Centre for Medical and Radiation PhysicsUniversity of WollongongWollongongNew South WalesAustralia
- Institute of Radiooncology‐ OncoRayHelmholtz‐Zentrum Dresden‐Rossendorf, RadiooncologyDresdenGermany
- Illawarra Cancer Care CentreWollongong HospitalWollongongNew South WalesAustralia
| | - John A. Baines
- College of Science and EngineeringJames Cook UniversityTownsvilleQueenslandAustralia
- Townsville Cancer CentreTownsville Hospital and Health ServiceTownsvilleQueenslandAustralia
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Powers M, Baines J. A comparison of measured and treatment planning system out-of-field dose for a 1.5 T MR linac. Phys Med Biol 2023; 68:20NT01. [PMID: 37699399 DOI: 10.1088/1361-6560/acf912] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2022] [Accepted: 09/12/2023] [Indexed: 09/14/2023]
Abstract
Objective.Dose due to the electron streaming effect (ESE) is a significant contribution to out-of-field dose on the Elekta Unity MR-Linac. The aim of this work is to provide a systematic comparison of calculated and measured streaming dose for this system.Approach.Beams 1.0 × 1.0 cm2to 5.0 × 5.0 cm2, gantry 90.0°, 1000 MU, were incident on an in-house phantom. At the beam entrance and exit surfaces of the phantom, ESE was generated in theY-direction (IEC 61217). EBT3 film, orientated within theX-Zplane and at 14.0 mm depth in a solid water block, was used to determine ESE dose 5.0 cm beyond the phantom. The experimental arrangement was simulated in the Monaco v5.4 treatment planning system (TPS), utilising a CT phantom dataset with differing relative electron densities (RED) for the surrounding air. Horizontal (Xdirection) and vertical (Zdirection) film dose profiles were compared to the corresponding TPS profiles.Main results. For each field, the maximum ESE dose was observed at the beam exit, the magnitude of which decreases with decreasing field size. For the 5.0 × 5.0 cm2field, the exit and entry ESE doses were 19.6% and 7.0% of theDmaxdose to water, respectively. Across horizontal profiles, differences (simulated-measured) were reduced with smaller fields and lower RED. The maximum absolute profile difference was 1.7% of theDmaxdose to water for optimal RED and isocentre location. In vertical profiles an offset consistent with the Lorentz force was observed relative to theX-Yisoplane.Significance. For the fields investigated, maximum absolute differences (simulated-measured) ≤ 5.2% occurred in peak regions of ESE, at the beam entrance and exit from the phantom. Generally, there is good agreement between Monaco simulated and measured ESE. Simulated out-of-field dose is sensitive to the RED assigned to air structures and unforced RED optimises out-of-field dose calculation accuracy.
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Affiliation(s)
- Marcus Powers
- Townsville Cancer Centre, Townsville Hospital and Health Service, Townsville, Queensland, Australia
- College of Science and Engineering, James Cook University, Townsville, Queensland, Australia
| | - John Baines
- Townsville Cancer Centre, Townsville Hospital and Health Service, Townsville, Queensland, Australia
- College of Science and Engineering, James Cook University, Townsville, Queensland, Australia
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Lee HH, Wang CY, Chen ST, Lu TY, Chiang CH, Huang MY, Huang CJ. Electron stream effect in 0.35 Tesla magnetic resonance image guided radiotherapy for breast cancer. Front Oncol 2023; 13:1147775. [PMID: 37519814 PMCID: PMC10373926 DOI: 10.3389/fonc.2023.1147775] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2023] [Accepted: 06/26/2023] [Indexed: 08/01/2023] Open
Abstract
Purpose This research aimed to analyze electron stream effect (ESE) during magnetic resonance image guided radiotherapy (MRgRT) for breast cancer patients on a MR-Linac (0.35 Tesla, 6MV), with a focus on the prevention of redundant radiation exposure. Materials and methods RANDO phantom was used with and without the breast attachment in order to represent the patients after breast conserving surgery (BCS) and those received modified radical mastectomy (MRM). The prescription dose is 40.05 Gy in fifteen fractions for whole breast irradiation (WBI) or 20 Gy single shot for partial breast irradiation (PBI). Thirteen different portals of intensity-modulated radiation therapy were created. And then we evaluated dose distribution in five areas (on the skin of the tip of the nose, the chin, the neck, the abdomen and the thyroid.) outside of the irradiated field with and without 0.35 Tesla. In addition, we added a piece of bolus with the thickness of 1cm on the skin in order to compare the ESE difference with and without a bolus. Lastly, we loaded two patients' images for PBI comparison. Results We found that 0.35 Tesla caused redundant doses to the skin of the chin and the neck as high as 9.79% and 5.59% of the prescription dose in the BCS RANDO model, respectively. For RANDO phantom without the breast accessory (simulating MRM), the maximal dose increase were 8.71% and 4.67% of the prescription dose to the skin of the chin and the neck, respectively. Furthermore, the bolus we added efficiently decrease the unnecessary dose caused by ESE up to 59.8%. Conclusion We report the first physical investigation on successful avoidance of superfluous doses on a 0.35T MR-Linac for breast cancer patients. Future studies of MRgRT on the individual body shape and its association with ESE influence is warranted.
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Affiliation(s)
- Hsin-Hua Lee
- Ph.D. Program in Environmental and Occupational Medicine, Kaohsiung Medical University and National Health Research Institutes, Kaohsiung, Taiwan
- Department of Radiation Oncology, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan
- Department of Radiation Oncology, Faculty of Medicine, School of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan
- Center for Cancer Research, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - Chun-Yen Wang
- Department of Radiation Oncology, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - Shan-Tzu Chen
- Department of Medical Imaging, Kaohsiung Municipal Siaogang Hospital, Kaohsiung, Taiwan
| | - Tzu-Ying Lu
- Department of Radiation Oncology, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - Cheng-Han Chiang
- Department of Radiation Oncology, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - Ming-Yii Huang
- Ph.D. Program in Environmental and Occupational Medicine, Kaohsiung Medical University and National Health Research Institutes, Kaohsiung, Taiwan
- Department of Radiation Oncology, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan
- Department of Radiation Oncology, Faculty of Medicine, School of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan
- Center for Cancer Research, Kaohsiung Medical University, Kaohsiung, Taiwan
- Graduate Institute of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - Chih-Jen Huang
- Department of Radiation Oncology, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan
- Department of Radiation Oncology, Faculty of Medicine, School of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan
- Center for Cancer Research, Kaohsiung Medical University, Kaohsiung, Taiwan
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Okamoto H, Igaki H, Chiba T, Shibuya K, Sakasai T, Jingu K, Inaba K, Kuroda K, Aoki S, Tatsumi D, Nakamura M, Kadoya N, Furuyama Y, Kumazaki Y, Tohyama N, Tsuneda M, Nishioka S, Itami J, Onishi H, Shigematsu N, Uno T. Practical guidelines of online MR-guided adaptive radiotherapy. JOURNAL OF RADIATION RESEARCH 2022; 63:730-740. [PMID: 35946325 PMCID: PMC9494538 DOI: 10.1093/jrr/rrac048] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Revised: 06/02/2022] [Indexed: 06/15/2023]
Abstract
The first magnetic resonance (MR)-guided radiotherapy system in Japan was installed in May 2017. Implementation of online MR-guided adaptive radiotherapy (MRgART) began in February 2018. Online MRgART offers greater treatment accuracy owing to the high soft-tissue contrast in MR-images (MRI), compared to that in X-ray imaging. The Japanese Society for Magnetic Resonance in Medicine (JSMRM), Japan Society of Medical Physics (JSMP), Japan Radiological Society (JRS), Japanese Society of Radiological Technology (JSRT), and Japanese Society for Radiation Oncology (JASTRO) jointly established the comprehensive practical guidelines for online MRgART. These guidelines propose the essential requirements for clinical implementation of online MRgART with respect to equipment, personnel, institutional environment, practice guidance, and quality assurance/quality control (QA/QC). The minimum requirements for related equipment and QA/QC tools, recommendations for safe operation of MRI system, and the implementation system are described. The accuracy of monitor chamber and detector in dose measurements should be confirmed because of the presence of magnetic field. The ionization chamber should be MR-compatible. Non-MR-compatible devices should be used in an area that is not affected by the static magnetic field (outside the five Gauss line), and their operation should be checked to ensure that they do not affect the MR image quality. Dose verification should be performed using an independent dose verification system that has been confirmed to be reliable through commissioning. This guideline proposes the checklists to ensure the safety of online MRgART. Successful clinical implementation of online MRgART requires close collaboration between physician, radiological technologist, nurse, and medical physicist.
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Affiliation(s)
- Hiroyuki Okamoto
- Radiation Safety and Quality Assurance Division, National Cancer Center Hospital, Tokyo, 104-0045, Japan
| | - Hiroshi Igaki
- Corresponding author. Department of Radiation Oncology, National Cancer Center Hospital, 5-1-1 Tsukiji, Chuo-ku, Tokyo 104-0045, Japan. Tel: +81(3)3542-2511; E-mail/Fax: , +81(3) 3547-5291
| | - Takahito Chiba
- Radiation Safety and Quality Assurance Division, National Cancer Center Hospital, Tokyo, 104-0045, Japan
| | - Keiko Shibuya
- Department of Radiation Oncology, Graduate School of Medicine, Osaka Metropolitan University, Osaka, 545-8586, Japan
| | - Tatsuya Sakasai
- Department of Radiological Technology, National Cancer Center Hospital, Tokyo, 104-0045, Japan
| | - Keiichi Jingu
- Department of Radiation Oncology, Tohoku University Graduate School of Medicine, Miyagi, 980-8574, Japan
| | - Koji Inaba
- Department of Radiation Oncology, National Cancer Center Hospital, Tokyo, 104-0045, Japan
| | - Kagayaki Kuroda
- Department of Human and Information Science, School of Information Science and Technology, Tokai University, Hiratsuka, 259-1292, Japan
| | - Shigeki Aoki
- Department of Radiology, Juntendo University Graduate School of Medicine, Tokyo, 113-8421, Japan
| | | | - Mitsuhiro Nakamura
- Department of Information Technology and Medical Engineering, Human Health Sciences, Graduate School of Medicine, Kyoto University, Kyoto, 606-8507, Japan
| | - Noriyuki Kadoya
- Department of Radiation Oncology, Tohoku University Graduate School of Medicine, Miyagi, 980-8574, Japan
| | - Yoshinobu Furuyama
- Department of Radiology, Chiba University Hospital, Chiba, 260-8677, Japan
| | - Yu Kumazaki
- Department of Radiation Oncology, International Medical Center, Saitama Medical University, Saitama, 350-1298, Japan
| | - Naoki Tohyama
- Division of Medical Physics, Tokyo Bay Advanced Imaging & Radiation Oncology Makuhari Clinic, Chiba, 261-0024, Japan
| | - Masato Tsuneda
- Department of Radiation Oncology, MR Linac ART Division, Graduate School of Medicine, Chiba University, Chiba, 260-8677, Japan
| | - Shie Nishioka
- Department of Radiation Oncology, Kyoto Second Red Cross Hospital, Kyoto, 602-8026, Japan
| | - Jun Itami
- Shin-Matsudo Accuracy Radiation Therapy Center, Shin-Matsudo Central General Hospital, Chiba, 270-0034, Japan
| | - Hiroshi Onishi
- Department of Radiology, University of Yamanashi, Yamanashi, 409-3898, Japan
| | - Naoyuki Shigematsu
- Department of Radiology, Keio University School of Medicine, Tokyo, 160-8582, Japan
| | - Takashi Uno
- Diagnostic Radiology and Radiation Oncology, Graduate School of Medicine, Chiba University, Chiba, 260-8677, Japan
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De-Colle C, Dohm O, Mönnich D, Nachbar M, Weidner N, Heinrich V, Boeke S, Gani C, Zips D, Thorwarth D. Estimation of secondary cancer projected risk after partial breast irradiation at the 1.5 T MR-linac. Strahlenther Onkol 2022; 198:622-629. [PMID: 35412045 PMCID: PMC9217770 DOI: 10.1007/s00066-022-01930-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Accepted: 03/10/2022] [Indexed: 10/26/2022]
Abstract
PURPOSE For patients treated with partial breast irradiation (PBI), potential long-term treatment-related toxicities are important. The 1.5 T magnetic resonance guided linear accelerator (MRL) offers excellent tumor bed visualization and a daily treatment plan adaption possibility, but MRL-specific electron stream and return effects may cause increased dose deposition at air-tissue interfaces. In this study, we aimed to investigate the projected risk of radiation-induced secondary malignancies (RISM) in patients treated with PBI at the 1.5 T MRL. METHODS Projected excess absolute risk values (EARs) for the contralateral breast, lungs, thyroid and esophagus were estimated for 11 patients treated with PBI at the MRL and compared to 11 patients treated with PBI and 11 patients treated with whole breast irradiation (WBI) at the conventional linac (CTL). All patients received 40.05 Gy in 15 fractions. For patients treated at the CTL, additional dose due to daily cone beam computed tomography (CBCT) was simulated. The t‑test with Bonferroni correction was used for comparison. RESULTS The highest projected risk for a radiation-induced secondary cancer was found for the ipsilateral lung, without significant differences between the groups. A lower contralateral breast EAR was found for MRL-PBI (EAR = 0.89) compared to CTL-PBI (EAR = 1.41, p = 0.01), whereas a lower thyroid EAR for CTL-PBI (EAR = 0.17) compared to MRL-PBI (EAR = 0.33, p = 0.03) and CTL-WBI (EAR = 0.46, p = 0.002) was observed. Nevertheless, when adding the CBCT dose no difference between thyroid EAR for CTL-PBI compared to MRL-PBI was detected. CONCLUSION Better breast tissue visualization and the possibility for daily plan adaption make PBI at the 1.5 T MRL particularly attractive. Our simulations suggest that this treatment can be performed without additional projected risk of RISM.
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Affiliation(s)
- C De-Colle
- Department of Radiation Oncology, University Hospital and Medical Faculty, Eberhard Karls University Tübingen, Hoppe-Seyler-Str. 3, 72076, Tübingen, Germany.
| | - O Dohm
- Section for Biomedical Physics, Department of Radiation Oncology, University Hospital and Medical Faculty, Eberhard Karls University Tübingen, Tübingen, Germany
| | - D Mönnich
- Section for Biomedical Physics, Department of Radiation Oncology, University Hospital and Medical Faculty, Eberhard Karls University Tübingen, Tübingen, Germany
| | - M Nachbar
- Section for Biomedical Physics, Department of Radiation Oncology, University Hospital and Medical Faculty, Eberhard Karls University Tübingen, Tübingen, Germany
| | - N Weidner
- Department of Radiation Oncology, University Hospital and Medical Faculty, Eberhard Karls University Tübingen, Hoppe-Seyler-Str. 3, 72076, Tübingen, Germany
| | - V Heinrich
- Department of Radiation Oncology, University Hospital and Medical Faculty, Eberhard Karls University Tübingen, Hoppe-Seyler-Str. 3, 72076, Tübingen, Germany
| | - S Boeke
- Department of Radiation Oncology, University Hospital and Medical Faculty, Eberhard Karls University Tübingen, Hoppe-Seyler-Str. 3, 72076, Tübingen, Germany
- partner site Tübingen, and German Cancer Research Center (DKFZ), German Cancer Consortium (DKTK), Heidelberg, Germany
| | - C Gani
- Department of Radiation Oncology, University Hospital and Medical Faculty, Eberhard Karls University Tübingen, Hoppe-Seyler-Str. 3, 72076, Tübingen, Germany
| | - D Zips
- Department of Radiation Oncology, University Hospital and Medical Faculty, Eberhard Karls University Tübingen, Hoppe-Seyler-Str. 3, 72076, Tübingen, Germany
- partner site Tübingen, and German Cancer Research Center (DKFZ), German Cancer Consortium (DKTK), Heidelberg, Germany
| | - D Thorwarth
- Section for Biomedical Physics, Department of Radiation Oncology, University Hospital and Medical Faculty, Eberhard Karls University Tübingen, Tübingen, Germany
- partner site Tübingen, and German Cancer Research Center (DKFZ), German Cancer Consortium (DKTK), Heidelberg, Germany
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Patterson E, Oborn BM, Cutajar D, Jelen U, Liney G, Rosenfeld AB, Metcalfe PE. Characterizing magnetically focused contamination electrons by off-axis irradiation on an inline MRI-Linac. J Appl Clin Med Phys 2022; 23:e13591. [PMID: 35333000 PMCID: PMC9195023 DOI: 10.1002/acm2.13591] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Revised: 12/10/2021] [Accepted: 03/02/2022] [Indexed: 11/18/2022] Open
Abstract
Purpose The aim of this study is to investigate off‐axis irradiation on the Australian MRI‐Linac using experiments and Monte Carlo simulations. Simulations are used to verify experimental measurements and to determine the minimum offset distance required to separate electron contamination from the photon field. Methods Dosimetric measurements were performed using a microDiamond detector, Gafchromic® EBT3 film, and MOSkinTM. Three field sizes were investigated including 1.9 × 1.9, 5.8 × 5.8, and 9.7 × 9.6 cm2. Each field was offset a maximum distance, approximately 10 cm, from the central magnetic axis (isocenter). Percentage depth doses (PDDs) were collected at a source‐to‐surface distance (SSD) of 1.8 m for fields collimated centrally and off‐axis. PDD measurements were also acquired at isocenter for each off‐axis field to measure electron contamination. Monte Carlo simulations were used to verify experimental measurements, determine the minimum field offset distance, and demonstrate the use of a spoiler to absorb electron contamination. Results Off‐axis irradiation separates the majority of electron contamination from an x‐ray beam and was found to significantly reduce in‐field surface dose. For the 1.9 × 1.9, 5.8 × 5.8, and 9.7 × 9.6 cm2 field, surface dose was reduced from 120.9% to 24.9%, 229.7% to 39.2%, and 355.3% to 47.3%, respectively. Monte Carlo simulations generally were within experimental error to MOSkinTM and microDiamond, and used to determine the minimum offset distance, 2.1 cm, from the field edge to isocenter. A water spoiler 2 cm thick was shown to reduce electron contamination dose to near zero. Conclusions Experimental and simulation data were acquired for a range of field sizes to investigate off‐axis irradiation on an inline MRI‐Linac. The skin sparing effect was observed with off‐axis irradiation, a feature that cannot be achieved to the same extent with other methods, such as bolusing, for beams at isocenter.
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Affiliation(s)
| | - Bradley M Oborn
- Centre for Medical Radiation Physics, Wollongong, NSW, Australia.,Illawarra Cancer Care Centre, Wollongong Hospital, Wollongong, NSW, Australia
| | - Dean Cutajar
- Centre for Medical Radiation Physics, Wollongong, NSW, Australia
| | - Urszula Jelen
- Ingham Institute for Applied Medical Research, Liverpool, NSW, Australia
| | - Gary Liney
- Ingham Institute for Applied Medical Research, Liverpool, NSW, Australia
| | - Anatoly B Rosenfeld
- Centre for Medical Radiation Physics, Wollongong, NSW, Australia.,Illawarra Health Medical Research Institute, University of Wollongong, Wollongong, NSW, Australia
| | - Peter E Metcalfe
- Centre for Medical Radiation Physics, Wollongong, NSW, Australia.,Ingham Institute for Applied Medical Research, Liverpool, NSW, Australia
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Okamoto H. [4. Treatment Planning in Magnetic Resonance Guided Radiotherapy]. Nihon Hoshasen Gijutsu Gakkai Zasshi 2022; 78:766-771. [PMID: 35858784 DOI: 10.6009/jjrt.2022-2053] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Affiliation(s)
- Hiroyuki Okamoto
- Radiation Safety and Quality Assurance Division, National Cancer Center Hospital
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Groot Koerkamp ML, van der Leij F, van 't Westeinde T, Bol GH, Scholten V, Bouwmans R, Mandija S, Philippens MEP, van den Bongard HJGD, Houweling AC. Prone vs. supine accelerated partial breast irradiation on an MR-Linac: A planning study. Radiother Oncol 2021; 165:193-199. [PMID: 34774649 DOI: 10.1016/j.radonc.2021.11.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Revised: 11/01/2021] [Accepted: 11/03/2021] [Indexed: 02/07/2023]
Abstract
BACKGROUND AND PURPOSE Accelerated partial breast irradiation (APBI) may benefit from the MR-Linac for target definition, patient setup, and motion monitoring. In this planning study, we investigated whether prone or supine position is dosimetrically beneficial for APBI on an MR-Linac and we evaluated patient comfort. MATERIALS AND METHODS Twenty-patients (9 postoperative, 11 preoperative) with a DCIS or breast tumor <3 cm underwent 1.5 T MRI in prone and supine position. The tumor or tumor bed was delineated as GTV and a 2 cm CTV-margin and 0.5 cm PTV-margin were added. 1.5 T MR-Linac treatment plans (5 × 5.2 Gy) with 11 beams were created for both positions in each patient. We evaluated the number of plans that achieved the planning constraints and performed a dosimetric comparison between prone and supine position using the Wilcoxon signed-rank test (p-value <0.01 for significance). Patient experience during scanning was evaluated with a questionnaire. RESULTS All 40 plans met the target coverage and OAR constraints, regardless of position. Heart Dmean was not significantly different (1.07 vs. 0.79 Gy, p-value: 0.027). V5Gy to the ipsilateral lung (4.4% vs. 9.8% median, p-value 0.009) and estimated delivery time (362 vs. 392 s, p-value: 0.003) were significantly lower for prone position. PTV coverage and dose to other OAR were comparable between positions. The majority of patients (13/20) preferred supine position. CONCLUSION APBI on the MR-Linac is dosimetrically feasible in prone and supine position. Mean heart dose was similar in both positions. Ipsilateral lung V5Gy was lower in prone position.
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Affiliation(s)
| | | | | | - Gijsbert H Bol
- Department of Radiotherapy, UMC Utrecht, The Netherlands
| | | | - Roel Bouwmans
- Department of Radiotherapy, UMC Utrecht, The Netherlands
| | - Stefano Mandija
- Department of Radiotherapy, UMC Utrecht, The Netherlands; Computational Imaging Group for MR Diagnostics & Therapy, Center for Image Sciences, UMC Utrecht, The Netherlands
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