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Bjegovic K, Sun L, Pandey P, Grilj V, Ballesteros-Zebadua P, Paisley R, Gonzalez G, Wang S, Vozenin MC, Limoli CL, Xiang SL. 4D in vivodosimetry for a FLASH electron beam using radiation-induced acoustic imaging. Phys Med Biol 2024; 69:115053. [PMID: 38722574 DOI: 10.1088/1361-6560/ad4950] [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: 02/22/2024] [Accepted: 05/09/2024] [Indexed: 06/01/2024]
Abstract
Objective. The primary goal of this research is to demonstrate the feasibility of radiation-induced acoustic imaging (RAI) as a volumetric dosimetry tool for ultra-high dose rate FLASH electron radiotherapy (FLASH-RT) in real time. This technology aims to improve patient outcomes by accurate measurements ofin vivodose delivery to target tumor volumes.Approach. The study utilized the FLASH-capable eRT6 LINAC to deliver electron beams under various doses (1.2 Gy pulse-1to 4.95 Gy pulse-1) and instantaneous dose rates (1.55 × 105Gy s-1to 2.75 × 106Gy s-1), for imaging the beam in water and in a rabbit cadaver with RAI. A custom 256-element matrix ultrasound array was employed for real-time, volumetric (4D) imaging of individual pulses. This allowed for the exploration of dose linearity by varying the dose per pulse and analyzing the results through signal processing and image reconstruction in RAI.Main Results. By varying the dose per pulse through changes in source-to-surface distance, a direct correlation was established between the peak-to-peak amplitudes of pressure waves captured by the RAI system and the radiochromic film dose measurements. This correlation demonstrated dose rate linearity, including in the FLASH regime, without any saturation even at an instantaneous dose rate up to 2.75 × 106Gy s-1. Further, the use of the 2D matrix array enabled 4D tracking of FLASH electron beam dose distributions on animal tissue for the first time.Significance. This research successfully shows that 4Din vivodosimetry is feasible during FLASH-RT using a RAI system. It allows for precise spatial (∼mm) and temporal (25 frames s-1) monitoring of individual FLASH beamlets during delivery. This advancement is crucial for the clinical translation of FLASH-RT as enhancing the accuracy of dose delivery to the target volume the safety and efficacy of radiotherapeutic procedures will be improved.
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Affiliation(s)
- Kristina Bjegovic
- The Department of Biomedical Engineering, University of California, Irvine, CA 92617, United States of America
| | - Leshan Sun
- The Department of Biomedical Engineering, University of California, Irvine, CA 92617, United States of America
| | - Prabodh Pandey
- Department of Radiological Sciences, University of California, Irvine, Irvine, CA 92697, United States of Americaica
| | - Veljko Grilj
- Laboratory of Radiation Oncology, Radiation Oncology Service and Oncology Department, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland
| | - Paola Ballesteros-Zebadua
- Laboratory of Radiation Oncology, Radiation Oncology Service and Oncology Department, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland
- Laboratory of Medical Physics, National Institute of Neurology and Neurosurgery, Mexico City, Mexico
| | - Ryan Paisley
- Laboratory of Radiation Oncology, Radiation Oncology Service and Oncology Department, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland
| | - Gilberto Gonzalez
- Department of Radiation Oncology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, United States of America
| | - Siqi Wang
- The Department of Biomedical Engineering, University of California, Irvine, CA 92617, United States of America
| | - Marie Catherine Vozenin
- Laboratory of Radiation Oncology, Radiation Oncology Service and Oncology Department, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland
- Sector of Radiobiology applied to Radiation Oncology, Radiation Oncology Service, Geneva University Hospital and University of Geneva, Geneva, Switzerland
| | - Charles L Limoli
- Department of Radiation Oncology, University of California, Irvine, Irvine, CA 92697-2695, United States of America
| | - Shawn Liangzhong Xiang
- The Department of Biomedical Engineering, University of California, Irvine, CA 92617, United States of America
- Department of Radiological Sciences, University of California, Irvine, Irvine, CA 92697, United States of Americaica
- Beckman Laser Institute & Medical Clinic, University of California, Irvine, Irvine, CA 92612, United States of America
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Pérez-Calatayud J, Sanchis-Sánchez E, Collado J, González V, Pérez-Calatayud I, Pérez-Calatayud MJ, Chimeno J, Carmona V, Luis Bonet-Sancho J, García-Sánchez AJ, Sanchis E. Phantom development for daily checks in electron intraoperative radiotherapy with a mobile linac. Phys Med 2020; 76:109-116. [PMID: 32673822 DOI: 10.1016/j.ejmp.2020.07.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Revised: 07/03/2020] [Accepted: 07/05/2020] [Indexed: 11/29/2022] Open
Abstract
PURPOSE IORT with mobile linear accelerators is a well-established modality where the dose rate and, therefore, the dose per pulse are very high. The constancy of the dosimetric parameters of the accelerator has to be checked daily. The aim of this work is to develop a phantom with embedded detectors to improve both accuracy and efficiency in the daily test of an IORT linac at the surgery room. METHODS The developed phantom is manufactured with transparent polymethyl methacrylate (PMMA), allocating 6 parallel-plate chambers: a central one to evaluate the on-axis beam output, another on-axis one placed at a fixed depth under the previous one to evaluate the energy constancy and four off-axis chambers to evaluate the flatness and symmetry. To analyse the readings a specific application has been developed. RESULTS For all chambers and energies, the mean saturation and polarization corrections were smaller than 0.7%. The beam is monitored at different levels of the clinical beam. Output, energy constancy and flatness correlate very well with the correspondent values with the complete applicator. During the first six months of clinical use the beam dosimetric parameters showed excellent stability. CONCLUSIONS A phantom has been developed with embedded parallel plate chambers attached to the upper applicator part of an IORT linac. The phantom allows a very efficient setup reducing the time to check the parameters. It provides complete dosimetric information (output, energy and flatness) with just one shot and using ionization chambers with minimum saturation effect, as this highly pulsed beam requires.
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Affiliation(s)
- José Pérez-Calatayud
- Department of Radiation Oncology, La Fe Polytechnic and University Hospital, Valencia, Spain
| | | | - Javier Collado
- Department of Electronic Engineering, University of Valencia, Spain
| | - Vicente González
- Department of Electronic Engineering, University of Valencia, Spain
| | - I Pérez-Calatayud
- Department of Electronic Engineering, University of Valencia, Spain.
| | - M J Pérez-Calatayud
- Department of Radiation Oncology, Fundación Instituto Valenciano de Oncología, Valencia, Spain
| | - José Chimeno
- Department of Radiation Oncology, La Fe Polytechnic and University Hospital, Valencia, Spain
| | - Vicente Carmona
- Department of Radiation Oncology, La Fe Polytechnic and University Hospital, Valencia, Spain
| | | | | | - Enrique Sanchis
- Department of Electronic Engineering, University of Valencia, Spain
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Baghani HR, Robatjazi M, Mahdavi SR. Performance evaluation and secondary monitor unit checkout for a dedicated accelerator in intraoperative electron radiotherapy. Radiat Phys Chem Oxf Engl 1993 2019. [DOI: 10.1016/j.radphyschem.2019.05.013] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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García-Cases F, Perez-Calatayud J, Ballester F, Vijande J, Granero D. Peripheral dose around a mobile linac for intraoperative radiotherapy: radiation protection aspects. JOURNAL OF RADIOLOGICAL PROTECTION : OFFICIAL JOURNAL OF THE SOCIETY FOR RADIOLOGICAL PROTECTION 2018; 38:1393-1411. [PMID: 30277221 DOI: 10.1088/1361-6498/aae5a0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The aim of this work is to analyse the scattered radiation produced by the mobile accelerator Mobetron 1000. To do so, detailed Monte Carlo simulations using two different codes, Penelope2008 and Geant4, were performed. Measurements were also done. To quantify the attenuation due to the internal structures, present in the accelerator head, on the scattered radiation produced, some of the main structural shielding in the Mobetron 1000 has been incorporated into the geometry simulation. Results are compared with measurements. Some discrepancies between the calculated and measured dose values were found. These differences can be traced back to the importance of the radiation component due to low energy scattered electrons. This encouraged us to perform additional calculations to separate the role played by this component. Ambient dose equivalent, H*(10), outside of the operating room (OR) has been evaluated using Geant4. H*(10) has been measured inside and outside the OR, being its values compatible with those reported in the literature once the low energy electron component is removed. With respect to the role played by neutrons, estimations of neutron H*(10) using Geant4 together with H*(10) measurements has been performed for the case of the 12 MeV electron beam. The values obtained agree with the experimental values existing in the literature, being much smaller than those registered in conventional accelerators. This study is a useful tool for the clinical user to investigate the radiation protection issues arising with the use of these accelerators in ORs without structural shielding. These results will also enable to better fix the maximum number of treatments that could be performed while insuring adequate radiological protection of workers and public in the hospital.
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Affiliation(s)
- F García-Cases
- Servicio de Radiofísica y Protección Radiológica, Hospital Universitario San Juan de Alicante, San Juan de Alicante, Spain
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Breast intraoperative radiotherapy: a review of available modalities, dedicated machines and treatment procedure. JOURNAL OF RADIOTHERAPY IN PRACTICE 2018. [DOI: 10.1017/s146039691800033x] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
AbstractBackgroundBreast intraoperative radiotherapy (IORT) is a partial irradiation technique that delivers a single fraction of radiation dose to the tumour bed during surgery. The use of this technique is increasing (especially in the Middle East), and therefore, it is essential to have a comprehensive approach to this treatment modality. The aim of this study is to conduct a literature review on available IORT modalities during breast irradiation as well as dedicated IORT machines and associated treatment procedures. The main IORT trials and corresponding clinical outcomes are also studied.Materials and MethodsA computerised search was performed through MEDLINE, PubMed, PubMed Central, ISI web of knowledge and reference list of related articles.ResultsIORT is now feasible through using two main modalities, including low-kilovolt IORT and intraoperative electron radiotherapy (IOERT). The dedicated machines employed and treatment procedure for mentioned modalities are quite different. The outcomes of implemented clinical trials showed that IORT is not inferior to external beam radiotherapy (EBRT) in specifically selected and well-informed patients and can be considered as an alternative to EBRT.ConclusionAlthough the clinical outcomes of introduced IORT methods are comparable, but based on the review results, it could be said that IOERT is the most effective technical method, in view of the treatment time and dose uniformity concepts. The popularity of IORT is mainly due to the distinguished obtained results during breast cancer treatment. Despite the presence of some technical challenges, it is expected that the IORT technique will become more widespread in the immediate future.
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Wootton LS, Meyer J, Kim E, Phillips M. Commissioning, clinical implementation, and performance of the Mobetron 2000 for intraoperative radiation therapy. J Appl Clin Med Phys 2017; 18:230-242. [PMID: 28291922 PMCID: PMC5689882 DOI: 10.1002/acm2.12027] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2016] [Accepted: 11/17/2016] [Indexed: 12/28/2022] Open
Abstract
The Mobetron is a mobile electron accelerator designed to deliver therapeutic radiation dose intraoperatively while diseased tissue is exposed. Experience with the Mobetron 1000 has been reported extensively. However, since the time of those publications a new model, the Mobetron 2000, has become commercially available. Experience commissioning this new model and 3 years of data from historical use are reported here. Descriptions of differences between the models are emphasized, both in physical form and in dosimetric characteristics. Results from commissioning measurements including output factors, air gap factors, percent depth doses (PDDs), and 2D dose profiles are reported. Output factors are found to have changed considerably in the new model, with factors as high as 1.7 being measured. An example lookup table of appropriate accessory/energy combinations for a given target dimension is presented, and the method used to generate it described. Results from 3 years of daily QA measurements are outlined. Finally, practical considerations garnered from 3 years of use are presented.
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Affiliation(s)
- Landon S Wootton
- Department of Radiation Oncology, University of Washington School of Medicine, Seattle, WA, USA
| | - Juergen Meyer
- Department of Radiation Oncology, University of Washington School of Medicine, Seattle, WA, USA
| | - Edward Kim
- Department of Radiation Oncology, University of Washington School of Medicine, Seattle, WA, USA
| | - Mark Phillips
- Department of Radiation Oncology, University of Washington School of Medicine, Seattle, WA, USA
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Abstract
Literature was reviewed to assess the physical aspects governing the present and emerging technologies used in intraoperative radiation therapy (IORT). Three major technologies were identified: treatment with electrons, treatment with external generators of kV X-rays and electronic brachytherapy. Although also used in IORT, literature on brachytherapy with radioactive sources is not systematically reviewed since an extensive own body of specialized literature and reviews exists in this field. A comparison with radioactive sources is made in the use of balloon catheters for partial breast irradiation where these are applied in almost an identical applicator technique as used with kV X-ray sources. The physical constraints of adaption of the dose distribution to the extended target in breast IORT are compared. Concerning further physical issues, the literature on radiation protection, commissioning, calibration, quality assurance (QA) and in-vivo dosimetry of the three technologies was reviewed. Several issues were found in the calibration and the use of dosimetry detectors and phantoms for low energy X-rays which require further investigation. The uncertainties in the different steps of dose determination were estimated, leading to an estimated total uncertainty of around 10-15% for IORT procedures. The dose inhomogeneity caused by the prescription of electrons at 90% and by the steep dose gradient of kV X-rays causes additional deviations from prescription dose which must be considered in the assessment of dose response in IORT.
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Affiliation(s)
- Frank W Hensley
- Department of Radiation Oncology, University Hospital of Heidelberg, Im Neuenheimer Feld 400, 69120, Heidelberg, Germany.
- , Present address: Birkenweg 35, 69221, Dossenheim, Germany.
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Meyer J, Nyflot MJ, Smith WP, Wottoon LS, Young L, Yang F, Kim M, Hendrickson KRG, Ford E, Kalet AM, Cao N, Dempsey C, Sandison GA. Electron beam energy QA - a note on measurement tolerances. J Appl Clin Med Phys 2016; 17:249-257. [PMID: 27074488 PMCID: PMC5875568 DOI: 10.1120/jacmp.v17i2.6049] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2015] [Revised: 11/24/2015] [Accepted: 11/17/2015] [Indexed: 11/29/2022] Open
Abstract
Monthly QA is recommended to verify the constancy of high‐energy electron beams generated for clinical use by linear accelerators. The tolerances are defined as 2%/2 mm in beam penetration according to AAPM task group report 142. The practical implementation is typically achieved by measuring the ratio of readings at two different depths, preferably near the depth of maximum dose and at the depth corresponding to half the dose maximum. Based on beam commissioning data, we show that the relationship between the ranges of energy ratios for different electron energies is highly nonlinear. We provide a formalism that translates measurement deviations in the reference ratios into change in beam penetration for electron energies for six Elekta (6‐18 MeV) and eight Varian (6‐22 MeV) electron beams. Experimental checks were conducted for each Elekta energy to compare calculated values with measurements, and it was shown that they are in agreement. For example, for a 6 MeV beam a deviation in the measured ionization ratio of ±15% might still be acceptable (i.e., be within ±2 mm), whereas for an 18 MeV beam the corresponding tolerance might be ±6%. These values strongly depend on the initial ratio chosen. In summary, the relationship between differences of the ionization ratio and the corresponding beam energy are derived. The findings can be translated into acceptable tolerance values for monthly QA of electron beam energies. PACS number(s): 87.55, 87.56
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Severgnini M, de Denaro M, Bortul M, Vidali C, Beorchia A. In vivo dosimetry and shielding disk alignment verification by EBT3 GAFCHROMIC film in breast IOERT treatment. J Appl Clin Med Phys 2014; 16:5065. [PMID: 25679150 PMCID: PMC5689990 DOI: 10.1120/jacmp.v16i1.5065] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2014] [Revised: 09/10/2014] [Accepted: 09/03/2014] [Indexed: 11/23/2022] Open
Abstract
Intraoperative electron radiation therapy (IOERT) cannot usually benefit, as conventional external radiotherapy, from software systems of treatment planning based on computed tomography and from common dose verify procedures. For this reason, in vivo film dosimetry (IVFD) proves to be an effective methodology to evaluate the actual radiation dose delivered to the target. A practical method for IVFD during breast IOERT was carried out to improve information on the dose actually delivered to the tumor target and on the alignment of the shielding disk with respect to the electron beam. Two EBT3 GAFCHROMIC films have been positioned on the two sides of the shielding disk in order to obtain the dose maps at the target and beyond the disk. Moreover the postprocessing analysis of the dose distribution measured on the films provides a quantitative estimate of the misalignment between the collimator and the disk. EBT3 radiochromic films have been demonstrated to be suitable dosimeters for IVD due to their linear dose-optical density response in a narrow range around the prescribed dose, as well as their capability to be fixed to the shielding disk without giving any distortion in the dose distribution. Off-line analysis of the radiochromic film allowed absolute dose measurements and this is indeed a very important verification of the correct exposure to the target organ, as well as an estimate of the dose to the healthy tissue underlying the shielding. These dose maps allow surgeons and radiation oncologists to take advantage of qualitative and quantitative feedback for setting more accurate treatment strategies and further optimized procedures. The proper alignment using elastic bands has improved the absolute dose accuracy and the collimator disk alignment by more than 50%.
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Affiliation(s)
- Mara Severgnini
- Department of Medical Physics, A.O.U. "Ospedali Riuniti" di Trieste, Italy.
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Agostinelli S, Gusinu M, Cavagnetto F, Garelli S, Zeverino M, Guenzi M, Corvò R, Taccini G. On-line optimization of intraoperative electron beam radiotherapy of the breast. Radiother Oncol 2012; 103:188-92. [PMID: 22342419 DOI: 10.1016/j.radonc.2012.01.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2011] [Revised: 01/12/2012] [Accepted: 01/19/2012] [Indexed: 11/18/2022]
Abstract
PURPOSE To optimize the dose delivery to the breast lumpectomy target treated with intraoperative electron beam radiotherapy (IOERT). MATERIALS AND METHODS Two tools have been developed in our MU calculation software NEMO X to improve the dose homogeneity and the in-vivo dosimetry effectiveness for IOERT treatments. Given the target (tumor bed) thickness measured by the surgeon, NEMO X can provide auto dose normalization to cover 95% of the target volume with 95% of the prescription dose (PD) and a "best guess" of the expected dosimeter dose (EDD) for a deep seated in-vivo dosimeter. The tools have been validated with the data of 91 patients treated with IOERT on a LIAC mobile accelerator. In-vivo dosimetry has been performed with microMOSFETs positioned on the shielding disk inserted between the tumor bed and the chest wall. RESULTS On average the auto normalization showed to provide better results if compared to conventional normalization rules in terms of mean target dose (|MTD-PD|/PD ≤ 5% in 95% vs. 53% of pts) and V107 percentage (left angle bracket V107 right angle bracket =19% vs. 32%). In-vivo dosimetry MOSFET dose (MD) showed a better correlation with the EDD guessed by our tool than just by assuming that EDD=PD (|MD-EDD|/EDD ≤ 5% in 57 vs. 26% of pts). CONCLUSIONS NEMO X provides two useful tools for the on-line optimization of the dose delivery in IOERT. This optimization can help to reduce unnecessary large over-dosage regions and allows introducing reliable action levels for in-vivo dosimetry.
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Affiliation(s)
- Stefano Agostinelli
- Department of Medical Physics, National Cancer Research Institute, Genova, Italy.
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Oshima T, Aoyama Y, Shimozato T, Sawaki M, Imai T, Ito Y, Obata Y, Tabushi K. An experimental attenuation plate to improve the dose distribution in intraoperative electron beam radiotherapy for breast cancer. Phys Med Biol 2009; 54:3491-500. [DOI: 10.1088/0031-9155/54/11/014] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Beddar AS, Briere TM, Ouzidane M. Intraoperative radiation therapy using a mobile electron linear accelerator: field matching for large-field electron irradiation. Phys Med Biol 2006; 51:N331-7. [PMID: 16953035 DOI: 10.1088/0031-9155/51/18/n01] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Intraoperative radiation therapy (IORT) consists of delivering a large, single-fraction dose of radiation to a surgically exposed tumour or tumour bed at the time of surgery. With the availability of a mobile linear accelerator in the OR, IORT procedures have become more feasible for medical centres and more accessible to cancer patients. Often the area requiring irradiation is larger than what the treatment applicators will allow, and therefore, two or more adjoining fields are used. Unfortunately, the divergence and scattering of the electron beams may cause significant dose variations in the region of the field junction. Furthermore, because IORT treatments are delivered in a large single fraction, the effects of underdosing or overdosing could be more critical when compared to fractionated external beam therapy. Proper matching of the fields is therefore an important technical aspect of treatment delivery. We have studied the matching region using the largest flat applicator available for three different possibilities: abutting the fields, leaving a small gap or creating an overlap. Measurements were done using film dosimetry for the available energies of 4, 6, 9 and 12 MeV. Our results show the presence of clinically significant cold spots for the low-energy beams when the fields are either gapped or abutted, suggesting that the fields should be overlapped. No fields should be gapped. The results suggest that an optimal dose distribution may be obtained by overlapping the fields at 4 and 6 MeV and simply abutting the fields at 9 and 12 MeV. However, due to uncertainties in the placement of lead shields during treatment delivery, one may wish to consider overlapping the higher energy fields as well.
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Affiliation(s)
- A S Beddar
- Department of Radiation Physics, Division of Radiation Oncology, The University of Texas M D Anderson Cancer Center, 1515 Holcombe Blvd, Box 94, Houston, TX 77030, USA.
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