Clinical dosimetry commissioning of 1.5 T MR-linac / 中华放射肿瘤学杂志

Objective:To introduce the clinical dosimetry commissioning methods and results of the 1.5 T MR-linac.Methods:In May, 2019, an Elekta Unity 1.5 T MR-linac was installed in Cancer Hospital, Chinese Academy of Medical Sciences and dosimetry commissioning was performed with magnetic field compatible measuring instruments. Commissioning items include absolute dose calibration, data acquisition and planning system model verification.Results:Absolute dose calibration in magnetic field should be corrected by magnetic field correction factor. The standard output dose of Unity was 87 cGy. Gamma analysis (3%/2 mm) was performed on the beam collection data and the planning system calculation data. The average pass rate of dose verification of standard field test cases was 96.41%, and the TG119 test case was 98.24%. The IROC end to end test case was 97.5%(7%/4 mm).Conclusions:The planning system model and the beam collection data have good consistency. The dose verification results of the standard field and TG119 test cases meet the general tolerance limit requirements of the AAPM TG218 report, and the verification results of the IROC end-to-end test cases meet the IROC center standards.

Selection, installation, and acceptance test of MRI simulator / 中华放射肿瘤学杂志

Magnetic resonance imaging (MRI) simulator (MRI-Sim) can provide superior images for radiotherapy.Due to the complexity of MRI technology and the safety problem caused by strong magnetic field, the acquisition and implementation of MRI simulation is more complicated than CT simulation.In order to ensure the introduction of MRI-Sim, this paper reviews the selection, installation, and acceptance test of MRI-Sim, including the selection of host and auxiliary equipment, installation site preparation, and safety precautions,as well as MRI-Sim acceptance test and commissioning.

Puesta en marcha del área de terapia ocupacional en servicio de rehabilitación, en el Hospital El Carmen / Starting the area of occupational therapy in rehabilitation services Hospital El Carmen

Los cambios demográficos y epidemiológicos asociados con el envejecimiento poblacional e incremento de enfermedades crónicas producen un aumento de las demandas en salud. Por este motivo, en los próximos años el Estado contempla la apertura de servicios de medicina física y rehabilitación que incorporen el área de terapia ocupacional en la red pública asistencial. El objetivo del presente documento es transmitir la experiencia de la puesta en marcha del área de terapia ocupacional en un hospital público. Se identifican 10 etapas a lo largo del proceso de implementación y puesta en marcha, cada una de ellas con sus respectivos facilitadores y obstaculizadores. Los principales resultados son la confección de protocolos de atención, de documentos técnicos asociados a la intervención, el fortalecimiento de la coordinación con la red de discapacidad, la terapia ocupacional como disciplina necesaria en estas unidades, el aumento de la demanda de atención, la buena recepción de los usuarios y la importancia de los equipos de trabajo. Como conclusiones destacan las habilidades particulares del equipo de trabajo para el desarrollo de procesos, la coordinación con la red para clarificar la pertinencia de ingreso de usuarios y los procesos de referencia y contra referencia. Y por último, la importancia de sistematizar la experiencia que facilite el traspaso de información a equipos que puedan ejecutarlo posteriormente.

Demographic and epidemiological changes associated with aging population and increasing chronic diseases result in increased health demands. For this reason the State plans to open services physical medicine and rehabilitation incorporating the area of occupational therapy in the coming years. The objective of this document is to convey the experience of the implementation of the area of occupational therapy in a public hospital. Ten stages are identified throughout the implementation process and implementation, each with their facilitators and obstructionist. The main results are translated into the making of care protocols, technical documents associated with the intervention, strengthening coordination with the network of disability, occupational therapy as necessary discipline in these units, increased demand for care, the good reception of users, the importance of the work teams, and systematization document. As findings highlight the particular skills of the work team development process, coordination with network to clarify the relevance of user input, reference and counter processes. And finally, the importance of systematizing the experience that facilitates the transfer of information to teams that can run later.

Commissioning of Axesse accelerator for volumetric modulated arc therapy / 中华放射肿瘤学杂志

Objective To test the accuracy and reliability of Axesse accelerator for volumetric modulated arc therapy (VMAT).Methods The accuracy and reliability of Axesse accelerator for VMAT were tested in a stepwise manner, from the simple to the complex and from the part to the whole.For the parts of the system, the stability of dosimetric output and the position accuracy of multi-leaf collimator (MLC) were tested.For the process of the system, the variable VMAT dose rates and gantry speed modulation, the MLC speed and dose rate modulation, and dosimetric verification in patients were tested.Results Compared with fixed gantry irradiation, the variation in dosimetric output was below 1.0% for rotary irradiation including the slide rotary irradiation of the dynamic MLC.The MLC position error of 0.5 mm was visible using the electronic portal imaging system of Axesse, iViewGT 3.40.The MLC position accuracy was within 1 mm for fixed gantry irradiation and rotary irradiation.In the range of the dose rate applied in clinical practice, the testing results of variable VMAT dose rates and gantry speeds as well as variable dose rates and MLC speeds showed that the variation between different strip-field beam intensities was below 2.0%.Using a gamma criterion of 3 mm/3%, the pass rates in dosimetric verification of patients with cervical cancer, prostate cancer, and breast cancer were 96.52%, 95.72%, and 98.83%, respectively.Conclusions The Axesse system can precisely control MLC motion, variable dose rates, and gantry speeds in VMAT.The Axesse system is accurate and reliable for VMAT.

Commissioning of intensity - modulated radiation therapy system with independent collimator / 中华放射肿瘤学杂志

Objective To perform an acceptance test for the IMRT system with independent collimator. Methods An ion chamber dosimeter were used to measure the startup characteristics of the accelerator and the absolute dose at isocenter and given characteristic points for three clinical cases ( a lower nasopharyngeal carcinoma, a lung cancer and a cervical cancer). The characteristic points represented the organs at risk or the target. A Mapeheck2 was used to measure dose maps of basic test fields and the treatment fields for the clinical cases. The basic test fields were as follows: 1 ). Symmetric fields in size of 2 cm ×2 cm, 5 cm ×5 cm, 10 cm× 10 cm, 20 cm ×20 cm, 2 cm × 10 cm, 10 cm ×2 cm, 5 cm ×20 cm and 20 cm ×5 cm;2). Asymmetric fields in size of 2 cm ×2 cm (x1 =4 cm, y1 = 10 cm;x2 = -2 cm, y2 = -8cm) and 5 cm ×5 cm (x1 = -2 cm, y1 = -5 cm;x2 =7 cm, y2 = 10 cm) ;3) A 20 cm ×20 cm composite field composed of five 20 cm× 4 cm narrow bar fields side by side. Gamma Index was used to compare calculated and corresponding measured dose distributions. When the criterion was 3% dose difference or 3 mm distance-to-agreement, the pass rate was required to be more than 90%. Results The accuracy of machine output was better than 2% when machine monitor units increased to 4. Among all basic test fields and all the treatment fields of three clinical cases, the maximal absolute dose error was -3.67%, and only the composite test field and two treatment fields of the lower nasopharyngeal carcinoma case had a pass rate slightly less than 90%, which were 83.6%, 88. 3% and 89. 7% ,respectively. For the three clinical cases the treatment delivery times were 15, 14, and 27 minutes, respectively. Conclusions The overall commissioning results are acceptable, and the system can be used in clinic.

Intensity Modulated Radiation Therapy Commissioning and Quality Assurance: Implementation of AAPM TG119 / 의학물리

The purpose of this study is to evaluate the accuracy of IMRT in our clinic from based on TG119 procedure and establish action level. Five IMRT test cases were described in TG119: multi-target, head&neck, prostate, and two C-shapes (easy&hard). There were used and delivered to water-equivalent solid phantom for IMRT. Absolute dose for points in target and OAR was measured by using an ion chamber (CC13, IBA). EBT2 film was utilized to compare the measured two-dimensional dose distribution with the calculated one by treatment planning system. All collected data were analyzed using the TG119 specifications to determine the confidence limit. The mean of relative error (%) between measured and calculated value was 1.2+/-1.1% and 1.2+/-0.7% for target and OAR, respectively. The resulting confidence limits were 3.4% and 2.6%. In EBT2 film dosimetry, the average percentage of points passing the gamma criteria (3%/3 mm) was 97.7+/-0.8%. Confidence limit values determined by EBT2 film analysis was 3.9%. This study has focused on IMRT commissioning and quality assurance based on TG119 guideline. It is concluded that action level were +/-4% and +/-3% for target and OAR and 97% for film measurement, respectively. It is expected that TG119-based procedure can be used as reference to evaluate the accuracy of IMRT for each institution.

Implementation and Evaluation of the Electron Arc Plan on a Commercial Treatment Planning System with a Pencil Beam Algorithm / 의학물리

Less execution of the electron arc treatment could in large part be attributed to the lack of an adequate planning system. Unlike most linear accelerators providing the electron arc mode, no commercial planning systems for the electron arc plan are available at this time. In this work, with the expectation that an easily accessible planning system could promote electron arc therapy, a commercial planning system was commissioned and evaluated for the electron arc plan. For the electron arc plan with use of a Varian 21-EX, Pinnacle3 (ver. 7.4f), with an electron pencil beam algorithm, was commissioned in which the arc consisted of multiple static fields with a fixed beam opening. Film dosimetry and point measurements were executed for the evaluation of the computation. Beam modeling was not satisfactory with the calculation of lateral profiles. Contrary to good agreement within 1% of the calculated and measured depth profiles, the calculated lateral profiles showed underestimation compared with measurements, such that the distance-to-agreement (DTA) was 5.1 mm at a 50% dose level for 6 MeV and 6.7 mm for 12 MeV with similar results for the measured depths. Point and film measurements for the humanoid phantom revealed that the delivered dose was more than the calculation by approximately 10%. The electron arc plan, based on the pencil beam algorithm, provides qualitative information for the dose distribution. Dose verification before the treatment should be mandatory.

Commissioning of a micro-MLC (mMLC) for Stereotactic Radiosurgery / 의학물리

The 4 bank mico-MLC (mMLC; Acculeaf, Direx, Isral) has been commissioned for clinical use of linac based stereotactic radiosurgery. The geometrical parameters to control the leaves were determined and comparisons between measured and calculated by the calculation model were performed in terms of absolute dose (cGy/100 MU). As a result of evaluating calculated dose for various field sizes and depths of 5 and 10 cm in water in the geometric condition of fixed SSD (source to surface distance) and fixed SCD (source to chamber distance), most of differences were within 1% for 6 MV and 15 MV x-rays. The penumbral widths at the isocenter were approximately evaluated to 0.29~0.43 cm depending on the field size for 6 MV and 0.36~0.51 cm for 15 MV x-rays. The average transmission and leakage for 6 MV and 15 MV x-rays were 6.6% and 7.4% respectively in single level of leaves fully closed. In case of dual level of leaves fully closed the measured transmission is approximately 0.5% for both 6 MV and 15 MV x-rays. Through the commissiong procedure we could verify the dose characteristics of mMLC and approximately evaluate the error ranges for treatment planning system.

Commissioning Manufacture of Overseas Drugs in China in view of the Amendment of the Pharmaceutical Affairs Law in Japan / 中国药房

OBJECTIVE:To provide references for Chinese pharmaceutical enterprises in developing commissioning manufacture of overseas drugs.METHODS:The registration system of medicine commissioning manufacture in China,Japan and other countries were compared.The current status of Chinese drugs commissioning manufacture and the feasibility for Chinese pharmaceutical enterprises to gain commissioning manufacture of overseas drugs were analyzed.RESULTS & CONCLUSIONS:Both the government and pharmaceutical enterprises in China should take advantage of the amendment of the pharmaceutical affairs Law in Japan to contribute to the development of commissioning manufacture of overseas drugs.