Study on the calibration for the outputs of photon and electron beams of dual-mode of linear accelerator based on IAEA 277 and 381 reports / 中国医学装备

Objective:To calibrate the absorbed doses of the configured ray water with different gears of energies in accelerator based on<The use of plane-parallel ionization chambers in high-energy electron and photon beams>of International Atomic Energy Agency(IAEA)277 and 381 reports,so as to ensure the accuracy of the output dose of the linear accelerator during clinical radiotherapy.Methods:Elekta Infinity linear accelerator was used in this study,and the photon beam energies were respectively 6MV flattening filter(FF)mode and 6MV flattening filter free(FFF)mode.The electron beam energies were respectively 4,6,8,10,12 and 15MeV.According to the IAEA TRS277 and TRS381 reports,the calibrations of output doses in photon and electron beam waters were performed respectively by using the PTW dosimeter,PTW30013 finger type of ionization chamber and PTW34001 parallel plate ionization chamber.The error of each step was analyzed,and the accuracies of the calibrations of using different standards for the output waters of linear accelerator were compared.Results:The output amounts of photon beams of FF mode and FFF mode of 6MV at the maximum dose point in water were respectively 1.003 and 1.008cGy/MU.The output amounts of the energy of each gear of electron beams of 4,6,8,10,12 and 15MeV at the maximum dose point in water were respectively 1.003,1.002,0.998,0.999,1.000 and 1.003 cGy/MU.The calibration of the output of each gear of energy rays at the maximum dose point in water was 1cCy corresponded to 1MU,which error was less than 1%.Conclusion:The calibration for the output dose amount of accelerator in water on the basis of IAEA TRS277 and trs381 can ensure the accuracy of the output dose of the accelerator.

Effects of two irradiation methods on alkaloids in Sophorae Flavescentis Radix and its preparations / 国际中医中药杂志

Objective:To study the effects of electron beam irradiation and 60Co irradiation on the composition changes of four alkaloids in Sophorae Flavescentis Radix, intermediate extracts of Sophorae Flavescentis Radix and Lixieling Tablets. Methods:Sophorae Flavescentis Radix, intermediate extracts of Sophorae Flavescentis Radix and Lixieling Tablets were irradiated at different doses of 0, 1.5, 3, 5, 7, 10, 20, 30, 40 kGy by electron beam irradiation and 60Co irradiation. The contents of oxymatrine, oxysophocarpine, matrine and sophocarpine were determined by HPLC, and the changes of the components before and after irradiation were compared. Results:Oxymatrine, oxysophocarpine, matrine and sophocarpine were among 0.046 9-0.937 4 μg, 0.020 5-0.410 4 μg, 0.098 9-1.977 9 μg, 0.048 7-0.973 1 μg, respectively. The linear relationship was good. The average recovery rates were 98.1%, 100.1%, 100.5%, 96.6%, respectively, and the RSDs were 1.69%, 2.03%, 3.14% and 1.10%, respectively. Electron beam irradiation and 60Co irradiation had no statistical significance on the changes of oxymatrine, oxysophocarpine, matrine and sophocarpine in Sophora flavescens, but had statistical significance in the contents of intermediate extracts of Sophorae Flavescentis Radix and Lixieling Tablets. Conclusion:The established method for the determination of matrine is accurate, reproducible, simple and practical, and can be used for the quality control of Lixieling Tablets. Irradiation has no significant effect on the content of Sophorae Flavescentis Radix, while high dose irradiation has significant effect on the intermediates and finished products of Sophorae Flavescentis Radix, which can provide a basis for quality control and sterilization irradiation of enterprises.

Dosimetric comparison between conventional IMRT and EBCRT combined with IMRT for post-mastectomy left-sided breast cancer patients / 中华放射医学与防护杂志

Objective:To investigate the dosimetric differences between conventional IMRT and electron beam conformal radiotherapy (EBCRT) combined with IMRT for post-mastectomy left-sided breast cancer patients.Methods:A total of 20 post-mastectomy left-sided breast cancer patients who were treated in the Ningbo First Hospital from June 2018 to October 2021 were retrospectively studied. The planning target volume (PTV) included the supra-and infra-clavicular regions(PTV sc)and the ipsilateral chest wall (PTV cw), and the prescribed dose was 50 Gy/25 f. All radiotherapy plans were designed using the Varian Eclipse treatment planning system (TPS). After that, the dose distribution of the target volume and the dose exposure of organs at risk (OARs) were compared and analyzed. Results:All the IMRT plans met the clinical requirements, yet 2/20 of the EBCRT combined with IMRT plans were not clinically accepted. For these two patients, the maximum chest wall thickness was 3.7 cm and 4.4 cm each, and the designed electron beam energy was 12 MeV and 15 MeV, respectively. The dose to the ipsilateral lung of these two patients exceeded the institution-specific dose limit standard. For the remaining 18 patients whose chest wall thickness was 3 cm or less, the designed electron beams were 9 MeV or less. All the EBCRT combined with IMRT plans were clinically accepted. The target dose distribution of the conventional IMRT was better than that of the EBCRT combined with IMRT (uniformity index (HI): PTV sc: t = -10.20, P<0.05; PTV cw: t = -9.24, P<0.05; conformal index (CI): PTV all: t = 10.39, P <0.05). For OARs, the V5 Gy, V20 Gy, and Dmean of the ipsilateral lung of EBCRT combined with IMRT were lower than those of IMRT ( t = 5.98, 6.30, 11.30, P <0.05). Specifically, the V25 Gy and Dmean of heart decreased by 8.3% and 4.79 Gy, respectively ( t = 15.23, 15.76, P<0.05), the Dmean of the left anterior descending coronary artery (LADCA) decreased by 44.03% ( t = 11.69, P <0.05), and the V5 Gy and Dmean of the contralateral breast decreased by 7.9% and 0.8 Gy, respectively ( t = 3.66, 4.93, P<0.05). The dosimetric differences of other OARs were not statistically significant ( P > 0.05). Conclusions:For post-mastectomy left-sided breast cancer patients with a chest wall thickness of less than 3 cm, EBCRT combined IMRT can significantly reduce the exposure dose to the heart, the ipsilateral lung, and the contralateral breast, which is beneficial to reducing the potential risk of long-term complications after radiotherapy and can further improve the long-term overall survival rate of patients. For patients with thick chest wall, IMRT plans are more technologically ideal.

Two-Dimensional Electron Beam Radiotherapy Planning System with Modeling Function / 中国医疗器械杂志

In order to adapt to different target shapes and protect the surrounding normal tissues, the design of two-dimensional electron beam radiotherapy planning requires additional lead blocks. But the Pinnacle treatment planning system can not directly shape the lead block conformity to the size of the beam field given by the doctor. Every time, physicists need to manually drag the lead block to form the required beam field. When meeting a two-dimensional electron beam treatment planning with the same field parameters as before, physicists need to rearrange the field for dose calculation, which greatly reduces the design efficiency of the two-dimensional electron beam treatment planning. In this study, we independently developed a two-dimensional electron beam radiotherapy planning system based on Qt Creator. The system can quickly design a two-dimensional electron beam radiotherapy plan, which reduces the repeated work of physicists.

Objective clinical outcome and patient satisfaction in self-assessment of postoperative electronic radiation for refractory keloids / 中华放射肿瘤学杂志

Objective:Objective To investigate the role of radiotherapy in the treatment of refractory keloids, evaluate the self-assessment degree of satisfaction of patients and compare with the objective outcomes.Methods:A total of 144 patients (290 lesions) with refractory keloids admitted to Peking Union Medical College Hospital from 2013 to 2018 were included in this study. The median age was 28 years old (range: 15-81 years old). All lesions were subjected to electronic radiation at postoperative 24h. The regime of 5 to 7MeV electron beam radiation therapy was adopted. The total dose was ranged from 16 to 18 Gy/2f (at 1-week interval). The median follow-up time was 48 months (range: 35-91 months). Patient and Observer Scar Assessment Scale (POSAS) was used to evaluate the degree of satisfaction. Multivariate analysis was performed by Cox proportional hazards model.Results:Among 290 keloids, 52 keloids (17.9%) relapsed in 3 to 42 months from the end of radiotherapy (median 12 months). The main side effects were hyperpigmentation and local incisional extension. Univariate analysis showed that local incisional color darker than skin, pruritus, pain and young age were associated with recurrence. Multivariate analysis indicated that local incisional color darker than skin and pain were the independent prognostic factors for scar recurrence. Recurrence, hyperpigmentation and local incisional extension were the main reasons for patients′ dissatisfaction.Conclusions:Postoperative electronic radiation can achieve satisfactory efficacy in the treatment of refractory keloids. Local incisional color darker than skin and pain are the independent prognostic factors of keloid recurrence. Patient self-assessment results are not fully consistent with the objective clinical outcomes and recurrence status.

Conformal electron beam radiotherapy using custom-made step bolus for postmastectomy chest wall irradiation: An institutional experience

Background: Postmastectomy radiation (PMRT) to the chest wall using electron beam treatment with uniform bolus was practiced at our institution. The planning target volume (PTV) included the chest wall and the internal mammary nodes (IMN) along with supraclavicular nodal regions. The varying thickness of the postmastectomy chest wall and the varying position of the IMN resulted in dose inhomogeneity in the PTV. In addition, there was the risk of increased lung and cardiac doses. In this prospective study, we report the making of a custom-made bolus using dental wax called “step bolus.” Materials and Methods: From March 2010 to January 2011, 167 patients received PMRT. As conformal photon plans were not acceptable in 48 patients, they were treated with single energy electrons and custom-made bolus. Results: Addition of the step bolus improved dose distribution to the PTV reduced the mean lung dose %, the mean heart dose % and lung dose (D10, D20, D30, D50, and D70). Forty-seven patients had Grade 2, and one patient had Grade 3 skin toxicity. Acute symptomatic radiation pneumonitis was observed in one patient. At 5 years, 29 patients were alive with a median follow-up of 32 months and no local recurrences were observed. One patient died of myocardial infarction unrelated to treatment, one patient did not come for follow-up, 22 patients had systemic metastases, and 24 patients were disease free. Conclusion: A custom-made step bolus using dental wax can be used for tissue compensation in electron beam therapy with resulting good local disease control and acceptable toxicity.

Optimization of low-energy electron beam production for superficial cancer treatments by Monte Carlo code

Context: Low energy electron beam has been being used widely for superficial cancer treatments. In the current study a design for production of very low energy electron beam, by different thickness of Perspex spoilers, is presented that may be used for skin cancer. Aims: MCNPX Monte Carlo code was used for modeling and simulations in the current study. An energy spoiler Perspex was modeled for degrading 4 MeV electron beam of Varian 2300 CD Linac. Materials and Methods: The thicknesses of 3, 7, and 10 mm were applied before electron applicator at a distance of 42 cm from phantom surface. Dosimetric properties of new electron beams including Rp, Dmax, E0, as well as the penumbra of the beam were investigated. Results: For the 3 mm spoiler, the superficial beam output decreased to 77%, and the Dmax, R90, R50, and RP were shifted to the depths of 4, 6, 9, and 12 mm, respectively. While for 10 mm filter the results were 5.2, 3.0 and 5.0 mm for R90, R50, and Rp, respectively. In addition, the surface dose was 93% and the Dmax was shifted to the depth of 1mm for the 10mm Perspex spoiler slab. Conclusions: The presented beam provides a novel surface dose, Dmax, and RP which can be applicable for treatment of skin cancers with minimum dose to the beyond normal tissues

Assessment of radiation leakage from treatment applicator of Siemens Primus Plus and Siemens Artiste linear accelerators

Aim: The purpose of this study is to measure radiation leakage of Siemens Primus Plus and Siemens Artiste linear accelerators in electron mode and to compare the leakage level with that recommended by the International Electrotechnical Commission (IEC) standard. Materials and Methods: In this assessment, Siemens Primus Plus linear accelerator with 10 cm × 10 cm, 15 cm × 15 cm, and 25 cm × 25 cm applicators was used. The radiation leakage in lateral and vertical directions was measured for Siemens Primus Plus and Siemens Artiste linear accelerators. Results: Data derived from radiation leakage measurement for Siemens Primus Plus and Siemens Artiste linear accelerators in lateral direction from the field edge and in vertical direction from the applicator were reported. The radiation leakage data were then compared with the IEC standard to evaluate in-air field leakage. Conclusion: Comparing the radiation leakage level from fields with the IEC standard for two applicators, the maximum that was occurred for 12 MeV electron beam and applicator size of 10 cm × 10 cm in Siemens Artiste linear accelerator was 2.3%, which is less than the IEC's recommended limit of 10%. It is concluded that the leakage amount is much less than the specified limit and that both of the linear accelerators have high level of safety. Considering the measurement stage, it also needs to be noted that the beam angle affected the radiation leakage level from field edge, and in 25° angle, it is higher than in 0° angle. Comparing radiation leakage from the right side of the field for the two linear accelerators, the amount of leakage for Siemens Primus Plus linear accelerator is more than Siemens Artiste linear accelerator

Clinical outcomes and prognostic factors in patients with mycosis fungoides who underwent radiation therapy in a single institution

PURPOSE: We aimed to evaluate clinical outcomes including progression-free survival (PFS), overall survival (OS), partial response, and complete response in patients who underwent radiation therapy (RT) for mycosis fungoides (MF). Also, we sought to find prognostic factors for clinical outcomes. MATERIALS AND METHODS: Total 19 patients confirmed with MF between 1999–2015 were retrospectively reviewed. Clinical and treatment characteristics, clinical outcomes, and and toxicities were analyzed. RESULTS: Eleven patients were treated with total skin electron beam radiotherapy (TSEBT) and 8 patients with involved field radiation therapy (IFRT) with median dose of 30 Gy, respectively. The median time interval from diagnosis to RT was 2.6 months (range, 0.4 to 87.3 months). The overall response rate was 100%; 11 patients (57.9%) had a complete response and 8 patients (42.1%) a partial response. The presence of positive lymph node at the time of consultation of RT was associated with lower OS (p = 0.043). In multivariate analysis, PFS was significantly lower for patients with increased previous therapies experienced following RT (p = 0.019) and for patients showing PR during RT (p = 0.044). There were no reported grade 3 or more skin toxicities related with RT. CONCLUSION: Both IFRT and TSEBT are effective treatment for MF patients. Patients with short disease course before RT or complete response during RT are expected to have longer PFS. Positive lymph node status at the initiation of RT was associated woth poor OS, suggesting other treatment modalities such as low-dose RT for patients with low life-expectancy.

Design and 3D-printing of titanium bone implants: brief review of approach and clinical cases

Additive manufacturing (AM) is an alternative metal fabrication technology. The outstanding advantage of AM (3D-printing, direct manufacturing), is the ability to form shapes that cannot be formed with any other traditional technology. 3D-printing began as a new method of prototyping in plastics. Nowadays, AM in metals allows to realize not only net-shape geometry, but also high fatigue strength and corrosion resistant parts. This success of AM in metals enables new applications of the technology in important fields, such as production of medical implants. The 3D-printing of medical implants is an extremely rapidly developing application. The success of this development lies in the fact that patient-specific implants can promote patient recovery, as often it is the only alternative to amputation. The production of AM implants provides a relatively fast and effective solution for complex surgical cases. However, there are still numerous challenging open issues in medical 3D-printing. The goal of the current research review is to explain the whole technological and design chain of bio-medical bone implant production from the computed tomography that is performed by the surgeon, to conversion to a computer aided drawing file, to production of implants, including the necessary post-processing procedures and certification. The current work presents examples that were produced by joint work of Polygon Medical Engineering, Russia and by TechMed, the AM Center of Israel Institute of Metals. Polygon provided 3D-planning and 3D-modelling specifically for the implants production. TechMed were in charge of the optimization of models and they manufactured the implants by Electron-Beam Melting (EBM®), using an Arcam EBM® A2X machine.