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1.
Article in Chinese | WPRIM | ID: wpr-880435

ABSTRACT

The transportation of electron is inseparable from vacuum environment. The maintenance of the vacuum system of Elekta linear accelerator depends on two sputtering ionic pumps at the gun end and the target end. The traveling wave acceleration were used in Elekta linear accelerators. And the design of the electron gun filament is detachable. Because of these two reasons, the vacuum stability is relatively weak. Only two vacuum values are used to reflect the operation state of the whole vacuum system, which causes a few failures but will not trigger a the machine interlock. Considering the complexity of whole vacuum system, the problem of vacuum caused by the failure of various components in vacuum system is analyzed in this paper. It is hoped that some useful repairing experience and suggestions for the maintenance engineers of linear accelerator to solve the vacuum fault and rebuild the vacuum can be provided quickly.


Subject(s)
Electrons , Particle Accelerators , Radiotherapy Dosage , Vacuum
2.
Article in Chinese | WPRIM | ID: wpr-880434

ABSTRACT

Clinically, beam matching can greatly improve the flexibility and efficiency of treating patients between different medical electron linacs. However, in addition to the regular quality assurance (QA) test of the machine performance of linacs, there is still a lack of comprehensive evaluation of the clinical radiotherapy performance of beam-matched linacs. In this paper, the performance of volumetric modulated arc therapy (VMAT) between three closely matched linacs was evaluated by statistical process control (SPC) technology. It was found that the average and median γ passing rates of the VMAT QA processes of the three linacs had little difference, but the process capability levels were at three different levels. The results show that SPC technology can effectively evaluate the performance of beam matching for medical electron linacs, improve the patient-specific VMAT QA processes, and guide clinical decision-making.


Subject(s)
Electrons , Particle Accelerators , Quality Assurance, Health Care , Radiotherapy Dosage , Radiotherapy Planning, Computer-Assisted , Radiotherapy, Intensity-Modulated
3.
Article in Chinese | WPRIM | ID: wpr-879262

ABSTRACT

Image-guided radiation therapy using magnetic resonance imaging (MRI) is a new technology that has been widely studied and developed in recent years. The technology combines the advantages of MRI imaging, and can offer online real-time tracking of tumor and adjacent organs at risk, as well as real-time optimization of radiotherapy plan. In order to provide a comprehensive understanding of this technology, and to grasp the international development and trends in this field, this paper reviews and summarizes related researches, so as to make the researchers and clinical personnel in this field to understand recent status of this technology, and carry out corresponding researches. This paper summarizes the advantages of MRI and the research progress of MRI linear accelerator (MR-Linac), online guidance, adaptive optimization, and dosimetry-related research. Possible development direction of these technologies in the future is also discussed. It is expected that this review can provide a certain reference value for clinician and related researchers to understand the research progress in the field.


Subject(s)
Magnetic Resonance Imaging , Particle Accelerators , Radiometry , Radiotherapy Planning, Computer-Assisted , Radiotherapy, Image-Guided
4.
Article in Chinese | WPRIM | ID: wpr-828195

ABSTRACT

This discussion attempts to organize and analyze the clinical purpose of various technologies developed by medical electron accelerators from the development history and clinical needs of radiotherapy products, so as to avoid the troubles caused by specific technical details and summarize the development of medical accelerators. Directly, the study provides differentiated development ideas for the development of domestic medical accelerators and ways and means to determine the dimensions of differentiated development.


Subject(s)
Particle Accelerators , Protective Devices
5.
Article in Chinese | WPRIM | ID: wpr-772571

ABSTRACT

Cancer therapy with accelerated proton or heavy ion beam is the most advanced radiotherapy technology, which is recognized by the international community at present. It is of great practical significance to study the medical proton and heavy ion accelerators and the radiotherapy technology, in order to promote the development of the advanced medical radiotherapy equipments and improve the quality of life of cancer patients in China. After a brief overview of cancer therapy with proton and heavy ion beam, this paper summarized and analyzed the application status of medical proton accelerators and medical heavy ion accelerators at home and abroad, and finally put forward the future development trends of medical proton and heavy ion accelerators and the radiotherapy technology, it can provide a reference for the progress and development strategies of the advanced radiotherapy equipments in China.


Subject(s)
China , Heavy Ions , Humans , Neoplasms , Therapeutics , Particle Accelerators , Proton Therapy , Protons , Quality of Life
6.
Article in Chinese | WPRIM | ID: wpr-772542

ABSTRACT

This study presents an electronic portal imaging devices (EPIDs) based on daily check tool for Linac that is usable for different cancer centers.Several images of open rectangle fields were acquired with EPID and the key items of daily Linac check were derived from the obtained images using an in-house developed automatic analysis software.The experiment results showed that each parameter calculated by this tool is as reliable as the corresponding result measured by the commercial quality assurance devices and its measuring efficiency is much higher.


Subject(s)
Electronics, Medical , Electrons , Particle Accelerators , Phantoms, Imaging , Radiometry , Software
7.
Article in English | WPRIM | ID: wpr-719473

ABSTRACT

Cytogenetic dosimetry is useful for evaluating the absorbed dose of ionizing radiation based on analysis of radiation-induced chromosomal aberrations. We created two types of in vitro dose-response calibration curves for dicentric chromosomes (DC) and translocations (TR) induced by X-ray irradiation, using an electron linear accelerator, which is the most frequently used medical device in radiotherapy. We irradiated samples from four healthy Korean individuals and compared the resultant curves between individuals. Aberration yields were studied in a total of 31,800 and 31,725 metaphases for DC and TR, respectively, obtained from 11 X-ray irradiation dose-points (0, 0.05, 0.1, 0.25, 0.5, 0.75, 1, 2, 3, 4, and 5 Gy). The dose-response relationship followed a linear-quadratic equation, Y=C+αD+βD², with the coefficients C=0.0011 for DC and 0.0015 for TR, α=0.0119 for DC and 0.0048 for TR, and β=0.0617 for DC and 0.0237 for TR. Correlation coefficients between irradiation doses and chromosomal aberrations were 0.971 for DC and 0.6 for TR, indicating a very strong and a moderate correlation, respectively. This is the first study implementing cytogenetic dosimetry following exposure to ionizing X-radiation.


Subject(s)
Calibration , Chromosome Aberrations , Cytogenetics , In Vitro Techniques , Particle Accelerators , Radiation, Ionizing , Radiotherapy
8.
Article in Chinese | WPRIM | ID: wpr-774484

ABSTRACT

Through repaired the RF driver momentary oscillation stop of Varian 2300CD linear accelerator, systematically and comprehensively expounds the three state machine mode of control system and the in-machine fault monitoring mechanism involved in maintainability of Varian high energy accelerator. It proposes an improved solution to bring RF driver output into interlock system, by doing so it can avoid the control computer breakdown and improve maintainability.


Subject(s)
Particle Accelerators , Reference Standards
9.
Rio de Janeiro; s.n; 2018. 91 f p. il.
Thesis in Portuguese | LILACS | ID: biblio-904966

ABSTRACT

Com o objetivo de contribuir para a tomada de decisão do processo de gestão de tecnologias no âmbito do SUS, foi desenvolvida neste trabalho, uma avaliação de custo efetividade que compare o uso do dexrazoxano em diferentes populações e o uso do acelerador de prótons com o de fótons para tratar crianças com meduloblastoma. O horizonte temporal de toda a vida do paciente e a perspectiva de análise do SUS, foram usados em ambos os estudos. Uma análise de impacto orçamentário para cada tecnologia também foi construída. Após uma busca na literatura, foi desenvolvido um modelo de Markov capaz de comparar o uso do dexrazoxano em 6 perfis de pacientes com risco de desenvolver cardiotoxicidade. Usar o medicamento nas crianças menores de 5 anos de idade se mostrou a alternativa mais custo-efetiva (ICER de R$6.156,96), seguido de usar em todos os pacientes (ICER de R$ 58.968,7). Caso o preço diminua a um valor menor que R$250,00 por frasco, a alternativa de usar em todas as crianças se torna a mais custo-efetiva. O impacto orçamentário ao final de 5 anos foi de R$30.622.404,81 para uso apenas nas crianças menores de 5 anos. Usar a tecnologia em todas as crianças, produziria um impacto incremental de R$ 94.352.898,77. Para avaliar o custo-efetividade do acelerador de prótons, foi desenvolvido um modelo de microssimulação comparando cenários de vida útil dos equipamentos e número de pacientes tratados. Como cenário base foi adotado os parâmetros de 50 pacientes com vida útil dos equipamentos de 20 anos. Para esse cenário, o ganho em QALY foi de 2,71 e o ICER médio de R$171.012,51/QALY. Para o limiar de disposição a pagar de 1 PIB percapita foi observado que a incorporação da tecnologia seria custo-efetiva, se fosse tratar a partir de 150 pacientes. A vida útil dos equipamentos e as outras variáveis tiveram participação limitada ao serem variadas na análise de sensibilidade, sem alterar significativamente as respostas do modelo. Ao final de 20 anos, o impacto orçamentário foi de R$ 345.598.440,91. O estudo recomenda a incorporação do dexrazoxano para crianças menores de 5 anos e não recomenda a incorporação do acelerador de prótons no tratamento do meduloblastoma em crianças


Subject(s)
Humans , Child , Child , Cost-Benefit Analysis/economics , Dexrazoxane/therapeutic use , Effectiveness , Health Evaluation/economics , Medulloblastoma/therapy , Particle Accelerators , Technology Assessment, Biomedical/economics
10.
Article in Chinese | WPRIM | ID: wpr-775548

ABSTRACT

This paper introduces the failure phenomenon, failure analysis, maintenance process and method of SIEMENS PRIMUS linear accelerator.


Subject(s)
Particle Accelerators , Radiotherapy Dosage
11.
Braz. j. med. biol. res ; 50(3): e5848, 2017. tab, graf
Article in English | LILACS | ID: biblio-839264

ABSTRACT

This study presents the characterization of an X-ray irradiator through dosimetric tests, which confirms the actual dose rate that small animals and cells will be exposed to during radiobiological experiments. We evaluated the linearity, consistency, repeatability, and dose distribution in the positions in which the animals or cells are placed during irradiation. In addition, we evaluated the performance of the X-ray tube (voltage and tube operating current), the radiometric survey (leakage radiation) and safety devices. The irradiator default setting was established as 160 kV and 25 mA. Tests showed that the dose rate was linear overtime (R2=1) and remained stable for long (constant) and short (repeatability) intervals between readings. The mean dose rate inside the animal cages was 1.27±0.06 Gy/min with a uniform beam of 95.40% (above the minimum threshold guaranteed by the manufacturer). The mean dose rate inside the cell plates was 0.92±0.19 Gy/min. The dose rate dependence with tube voltage and current presented a quadratic and linear relationship, respectively. There was no observed mechanical failure during evaluation of the irradiator safety devices and the radiometric survey obtained a maximum ambient equivalent dose rate of 0.26 mSv/h, which exempts it from the radiological protection requirements of the International Atomic Energy Agency. The irradiator characterization enables us to perform radiobiological experiments, and assists or even replaces traditional therapy equipment (e.g., linear accelerators) for cells and small animal irradiation, especially in early research stages.


Subject(s)
Animals , Radiation Dosage , Radiometry/instrumentation , Calibration , Equipment Design , Particle Accelerators , Radiometry/methods , X-Rays
12.
Article in English | WPRIM | ID: wpr-63846

ABSTRACT

Central neurocytoma (CN) typically presents as an intraventricular mass causing obstructive hydrocephalus. The first line of treatment is surgical resection with adjuvant conventional radiotherapy. Stereotactic radiosurgery (SRS) was proposed as an alternative therapy for CN because of its lower risk profile. The objective of this systematic analysis is to assess the efficacy of SRS for CN. A systematic analysis for CN treated with SRS was conducted in PubMed. Baseline patient characteristics and outcomes data were extracted. Heterogeneity and publication bias were also assessed. Univariate and multivariate linear regressions were used to test for correlations to the primary outcome: local control (LC). The estimated cumulative rate of LC was 92.2% (95% confidence interval: 86.5-95.7%, p<0.001). Mean follow-up time was 62.4 months (range 3-149 months). Heterogeneity and publication bias were insignificant. The univariate linear regression models for both mean tumor volume and mean dose were significantly correlated with improved LC (p<0.001). Our data suggests that SRS may be an effective and safe therapy for CN. However, the rarity of CN still limits the efficacy of a quantitative analysis. Future multi-institutional, randomized trials of CN patients should be considered to further elucidate this therapy.


Subject(s)
Brain Neoplasms , Follow-Up Studies , Humans , Hydrocephalus , Linear Models , Neurocytoma , Particle Accelerators , Population Characteristics , Publication Bias , Radiosurgery , Radiotherapy , Tumor Burden
13.
Chinese Medical Journal ; (24): 284-288, 2016.
Article in English | WPRIM | ID: wpr-310664

ABSTRACT

<p><b>BACKGROUND</b>Volumetric-modulated arc therapy (VMAT) can only be implemented on the new generation linacs such as the Varian Trilogy® and Elekta Synergy®. This prevents most existing linacs from delivering VMAT. The purpose of this study was to investigate the feasibility of using a conventional linear accelerator delivering constant dose rate and constant angular spacing intensity-modulated arc therapy (CDR-CAS-IMAT) for treating cervical cancer.</p><p><b>METHODS</b>Twenty patients with cervical cancer previously treated with intensity-modulated radiation therapy (IMRT) using Varian Clinical 23EX were retreated using CDR-CAS-IMAT. The planning target volume (PTV) was set as 50.4 Gy in 28 fractions. Plans were evaluated based on the ability to meet the dose volume histogram. The homogeneity index (HI), target volume conformity index (CI), the dose to organs at risk, radiation delivery time, and monitor units (MUs) were also compared. The paired t-test was used to analyze the two data sets. All statistical analyses were performed using SPSS 19.0 software.</p><p><b>RESULTS</b>Compared to the IMRT group, the CDR-CAS-IMAT group showed better PTV CI (0.85 ± 0.03 vs. 0.81 ± 0.03, P = 0.001), clinical target volume CI (0.46 ± 0.05 vs. 0.43 ± 0.05, P = 0.001), HI (0.09 ± 0.02 vs. 0.11 ± 0.02, P = 0.005) and D95 (5196.33 ± 28.24 cGy vs. 5162.63 ± 31.12 cGy, P = 0.000), and cord D2 (3743.8 ± 118.7 cGy vs. 3806.2 ± 98.7 cGy, P = 0.017) and rectum V40 (41.9 ± 6.1% vs. 44.2 ± 4.8%, P = 0.026). Treatment time (422.7 ± 46.7 s vs. 84.6 ± 7.8 s, P = 0.000) and the total plan Mus (927.4 ± 79.1 vs. 787.5 ± 78.5, P = 0.000) decreased by a factor of 0.8 and 0.15, respectively. The IMRT group plans were superior to the CDR-CAS-IMAT group plans considering decreasing bladder V50 (17.4 ± 4.5% vs. 16.6 ± 4.2%, P = 0.049), bowel V30 (39.6 ± 6.5% vs. 36.6 ± 7.5%, P = 0.008), and low-dose irradiation volume; there were no significant differences in other statistical indexes.</p><p><b>CONCLUSIONS</b>Patients with cervical cancer treated with CDR-CAS-IMAT using Varian Clinical 23EX can get equivalent or superior dose distribution compared to those treated with IMRT. CDR-CAS-IMAT has a less treatment time and MU, which can reduce the uncertainty factor and patient discomfort in treatment.</p>


Subject(s)
Female , Humans , Particle Accelerators , Radiotherapy, Intensity-Modulated , Methods , Software , Uterine Cervical Neoplasms , Therapeutics
14.
Braz. j. med. biol. res ; 48(10): 908-914, Oct. 2015. tab, ilus
Article in English | LILACS | ID: lil-761605

ABSTRACT

Biological dosimetry (biodosimetry) is based on the investigation of radiation-induced biological effects (biomarkers), mainly dicentric chromosomes, in order to correlate them with radiation dose. To interpret the dicentric score in terms of absorbed dose, a calibration curve is needed. Each curve should be constructed with respect to basic physical parameters, such as the type of ionizing radiation characterized by low or high linear energy transfer (LET) and dose rate. This study was designed to obtain dose calibration curves by scoring of dicentric chromosomes in peripheral blood lymphocytes irradiated in vitro with a 6 MV electron linear accelerator (Mevatron M, Siemens, USA). Two software programs, CABAS (Chromosomal Aberration Calculation Software) and Dose Estimate, were used to generate the curve. The two software programs are discussed; the results obtained were compared with each other and with other published low LET radiation curves. Both software programs resulted in identical linear and quadratic terms for the curve presented here, which was in good agreement with published curves for similar radiation quality and dose rates.


Subject(s)
Adult , Humans , Male , Chromosome Aberrations/radiation effects , Dose-Response Relationship, Radiation , Electrons , Leukocytes, Mononuclear/radiation effects , Particle Accelerators , Calibration/standards , Primary Cell Culture , Radiation Dosage , Radiometry/methods
15.
Rev. bras. hematol. hemoter ; 37(3): 153-159, May-Jun/2015. tab, graf
Article in English | LILACS | ID: lil-752538

ABSTRACT

Irradiation of blood components with ionizing radiation generated by a specific device is recommended to prevent transfusion-associated graft-versus-host disease. However, a lin- ear accelerator can also be used in the absence of such a device, which is the case of the blood bank facility studied herein. In order to evaluate the quality of the irradiated packed red blood cells, this study aimed to determine whether the procedure currently employed in the facility is effective in inhibiting the proliferation of T lymphocytes without damaging blood components. The proliferation of T lymphocytes, plasma potassium levels, and the degree of hemolysis were evaluated and compared to blood bags that received no irradiation. Packed red blood cell bags were irradiated at a dose of 25 Gy in a linear accelerator. For this purpose, a container was designed to hold the bags and to ensure even distribution of irradiation as evaluated by computed tomography and dose-volume histogram. Irradiation was observed to inhibit the proliferation of lymphocytes. The percentage of hemolysis in irradiated bags was slightly higher than in non-irradiated bags (p-value >0.05), but it was always less than 0.4% of the red cell mass. Although potassium increased in both groups, it was more pronounced in irradiated red blood cells, especially after seven days of storage, with a linear increase over storage time. The findings showed that, at an appropriate dosage and under validated conditions, the irradiation of packed red blood cells in a linear accelerator is effective, inhibiting lymphocyte proliferation but without compromising the viability of the red cells.


Subject(s)
Blood Safety , Erythrocytes , Hemotherapy Service , Particle Accelerators , Radiation , Radiation, Ionizing , T-Lymphocytes
16.
Article in Chinese | WPRIM | ID: wpr-317762

ABSTRACT

<p><b>OBJECTIVE</b>To establish a miniature pig model of mandibular osteoradionecrosis (ORN).</p><p><b>METHODS</b>A single dose of irradiation (IR25 Gy, 28 Gy) was delivered via an electronic linear accelerator to the right mandible of 24 miniature pigs by utilizing three dimensional conformal radiotherapy (3D-CRT). The first molar of the mandible was extracted 2 months after radiation. Mandibular ORN was diagnosed through gross observation, X-ray film, CT, and histopathologic examination.</p><p><b>RESULTS</b>At 3-4 months after radiation, all animals suffered from mandibular ORN after dental extraction. The symptoms of ORN were more severe in the 28 Gy group than in the 25 Gy group.</p><p><b>CONCLUSION</b>A miniature pig model of mandibular ORN can be established through 25 Gy irradiation + dental extraction.</p>


Subject(s)
Animals , Mandible , Mandibular Diseases , Pathology , Molar , Osteoradionecrosis , Pathology , Particle Accelerators , Radiation Injuries, Experimental , Pathology , Radiotherapy, Conformal , Swine , Swine, Miniature , Tooth Extraction
17.
Radiation Oncology Journal ; : 261-264, 2015.
Article in English | WPRIM | ID: wpr-73629

ABSTRACT

External beam radiotherapy can be used to treat cutaneous squamous cell carcinomas (SCC). Acute skin toxicity is the most common adverse event. In this case study we report on an elderly patient with nasal root cutaneous SCC treated with stereotactic technique using a dedicated linear accelerator (CyberKnife system). Grade 3 skin toxicity was observed but it was resolved after 6 weeks. The use of stereotactic radiotherapy permitted a clinical remission of SCC with good cosmetic results.


Subject(s)
Aged , Carcinoma, Squamous Cell , Humans , Particle Accelerators , Radiosurgery , Radiotherapy , Skin , Skin Neoplasms , Stereotaxic Techniques , Vitamin E
18.
Radiation Oncology Journal ; : 337-343, 2015.
Article in English | WPRIM | ID: wpr-70159

ABSTRACT

PURPOSE: The purpose of this report is to describe the proton therapy system at Samsung Medical Center (SMC-PTS) including the proton beam generator, irradiation system, patient positioning system, patient position verification system, respiratory gating system, and operating and safety control system, and review the current status of the SMC-PTS. MATERIALS AND METHODS: The SMC-PTS has a cyclotron (230 MeV) and two treatment rooms: one treatment room is equipped with a multi-purpose nozzle and the other treatment room is equipped with a dedicated pencil beam scanning nozzle. The proton beam generator including the cyclotron and the energy selection system can lower the energy of protons down to 70 MeV from the maximum 230 MeV. RESULTS: The multi-purpose nozzle can deliver both wobbling proton beam and active scanning proton beam, and a multi-leaf collimator has been installed in the downstream of the nozzle. The dedicated scanning nozzle can deliver active scanning proton beam with a helium gas filled pipe minimizing unnecessary interactions with the air in the beam path. The equipment was provided by Sumitomo Heavy Industries Ltd., RayStation from RaySearch Laboratories AB is the selected treatment planning system, and data management will be handled by the MOSAIQ system from Elekta AB. CONCLUSION: The SMC-PTS located in Seoul, Korea, is scheduled to begin treating cancer patients in 2015.


Subject(s)
Cyclotrons , Helium , Humans , Korea , Metallurgy , Particle Accelerators , Patient Positioning , Proton Therapy , Protons , Radiation Oncology , Respiratory System , Seoul
19.
Article in English | WPRIM | ID: wpr-80670

ABSTRACT

PURPOSE: In order to keep the acceptable level of the radiation oncology linear accelerators, it is necessary to apply a reliable quality assurance (QA) program. MATERIALS AND METHODS: The QA protocols, published by authoritative organizations, such as the American Association of Physicists in Medicine (AAPM), determine the quality control (QC) tests which should be performed on the medical linear accelerators and the threshold levels for each test. The purpose of this study is to increase the accuracy and precision of the selected QC tests in order to increase the quality of treatment and also increase the speed of the tests to convince the crowded centers to start a reliable QA program. A new method has been developed for two of the QC tests; optical distance indicator (ODI) QC test as a daily test and gantry angle QC test as a monthly test. This method uses an image processing approach utilizing the snapshots taken by the CCD camera to measure the source to surface distance (SSD) and gantry angle. RESULTS: The new method of ODI QC test has an accuracy of 99.95% with a standard deviation of 0.061 cm and the new method for gantry angle QC has a precision of 0.43degrees. The automated proposed method which is used for both ODI and gantry angle QC tests, contains highly accurate and precise results which are objective and the human-caused errors have no effect on the results. CONCLUSION: The results show that they are in the acceptable range for both of the QC tests, according to AAPM task group 142.


Subject(s)
Particle Accelerators , Quality Control , Radiation Oncology
20.
Article in Chinese | WPRIM | ID: wpr-239200

ABSTRACT

<p><b>OBJECTIVE</b>To study the correction of algorithm for Varian enhanced dynamic wedge(EDW) factors and compare the dose/monitor unit (MU) deviation measured at the central axis of EDW field with that obtained by manual calculation or using the treatment planning system.</p><p><b>METHODS</b>EDW factors and dose were measured with Thimble ion chamber at 10 cm depth under the water for 6 MV and 10 MV photon on Varian linear accelerator. The corresponding calculations were done with the radiation treatment planning system. An analytic formula, namely the MU Fraction model, was used to calculate the EDW factor, which was corrected with a constant factor. The MU of conventional 2-D planning derived from manual calculating, treatment planning system, and actual measurements were compared.</p><p><b>RESULTS</b>With the measured results as the standard, the corrected manual calculation deviation of EDW factors was significantly reduced. For photon 6 MV, the maximum deviation reduced from 4.2% to 1.3% for 60° symmetry fields was, and from -4.7% to -1.8% for asymmetric fields. For photon 10 MV, the maximum deviation for all EDW fields was reduced from -3.0% to 1.1%. Comparison of the manual calculations with the measured results showed a MU deviation for symmetric fields within 2%, and more than 5% for some asymmetric fields. The deviation between the calculations of the treatment planning and the measured results was less than 1.5%.</p><p><b>CONCLUSION</b>Constant factor correction can effectively reduce the deviation of manual calculation. For MU calculation of EDW field in conventional 2-D dimensional treatment planning, the corrected results of symmetric fields meet clinical requirements. While the minimum distance between the field edge and the central axis was less than 4 cm in asymmetric fields, the corresponding special method, measurement or the treatment planning system should be used to calculate the dose/MU.</p>


Subject(s)
Algorithms , Models, Theoretical , Particle Accelerators , Radiotherapy Dosage , Radiotherapy Planning, Computer-Assisted
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