At present, the C-arm structure accelerators commonly used in radiotherapy equipment are complex in operation and have potential safety hazards when realizing non-coplanar treatment. By combining with medical robotic arm technology, a spherical radiotherapy accelerator motion system is designed. The beam module is clamped by the medical robotic arm structure to achieve three-dimensional multi-angle irradiation treatment within the non-coplanar angle range. Firstly, the rotating mechanism, beam module, and MLC module of the spherical radiotherapy equipment are designed. Then, the double-plane counterweight method is used to calculate the dynamic balance of the equipment, ensuring that the beam center point does not rotate during the treatment process. Finally, the strength check and reliability analysis of the transmission component gear are conducted. The results show that the designed spherical radiotherapy accelerator motion system can meet the requirements of stable, accurate, and fast precision radiotherapy, which is conducive to improving the treatment efficiency.
Particle Accelerators/instrumentation* ; Equipment Design ; Reproducibility of Results ; Radiotherapy/instrumentation*

OBJECTIVE: To investigate the influence of different scanning conditions on the image quality of medical electron accelerator cone-beam computed tomography (CBCT) and provide a reference for the selection of scanning conditions for different body parts. Methods Set different scanning conditions, the Catphan 503 phantom was scanned using CBCT parameters to analyze the influence of spatial resolution, noise, uniformity, spatial geometric accuracy, and low-contrast resolution on the image quality of CBCT. RESULTS: For the head, chest, and abdomen, with the increase in scanning parameter values, the noise value decreased by 47.4%, 26.1%, and 51.3% respectively, and the uniformity values decreased by 30.2%, 26.6%, and 47.9% respectively. The low-contrast resolution values decreased by 50.6%, 34.2%, and 12.0%. The influence of different scanning conditions on spatial geometric accuracy and spatial resolution is not significant. CONCLUSION Different scanning parameters have a certain influence on the image quality of medical electron accelerator CBCT. Lower scanning parameters can be selected based on individual patients to reduce the additional radiation dose, providing a reference for the safe application of CBCT image guidance in radiotherapy.
Cone-Beam Computed Tomography/instrumentation* ; Phantoms, Imaging ; Particle Accelerators

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.
Equipment Design ; Particle Accelerators ; Radiotherapy/instrumentation*

The security system plays an important role to protect the safety of patients and equipment in radiotherapy. The principle and structure of three kinds of security system of the Siemens digital linear accelerator were analyzed with some examples.
Equipment Safety ; Particle Accelerators ; instrumentation ; Radiotherapy Planning, Computer-Assisted ; instrumentation

UNLABELLEDThe aim of this study is to investigate the characteristics of Elekta delivery system for volumetric modulated arc therapy (VMAT). Five VMAT plans were delivered in service mode and dose rates, and speed of gantry and MLC leaves were analyzed by log files. Results showed that dose rates varied between 6 dose rates. Gantry and MLC leaf speed dynamically varied during delivery.

CONCLUSIONThe technique of VMAT requires linac to dynamically control more parameters, and these key dynamic variables during VMAT delivery can be checked by log files. Quality assurance procedure should be carried out for VMAT related parameter.

Humans ; Particle Accelerators ; Radiotherapy Dosage ; Radiotherapy, Intensity-Modulated ; instrumentation ; methods

OBJECTIVETo evaluate the clinical feasibility of daily quality assurance for linac radiation field by analyzing the trend of the daily testing data about parameter of radiation field.

METHODSTwo-dimensional ion chamber array Daily QA3 was used to measure the difference between the practical value and the standard value of the parameter about radiation field before commencing daily treatment. Farmer type ionization chambers from IBA Co. with DOSE1 dosimeter was used for the absolute dosimetry of photon and electron beams. Light/radiation field coincidence was checked by using films every month. The daily testing data (from 11/28/2009 to 4/8/2011) were reviewed and analyzed.

RESULTSX-ray and electron output was increasing steadily; light/radiation field coincidence, beam flatness constancy and symmetry of X- ray and electron was keeping stable.

CONCLUSIONThe procedures for daily quality assurance of linac radiation field, which will provide reference for long term linac calibration, are feasible in our experience.

Feasibility Studies ; Particle Accelerators ; Quality Control ; Radiometry ; instrumentation ; methods

BACKGROUND AND OBJECTIVEThe planning dose distribution of intensity-modulated radiation therapy (IMRT) has to be verified before clinical implementation. The commonly used verification method is to measure the beam fluency at 0 degree gantry angle with a 2-dimensional (2D) detector array, but not the composite dose distribution of the real delivery in the planned gantry angles. This study was to investigate the angular dependence of a 2D diode array (2D array) and the feasibility of using it to verify the composite dose distribution of IMRT.

METHODSAngular response of the central detector in the 2D array was measured for 6 MV X-ray, 10 cmx10 cm field and 100 cm source axis distance (SAD) in different depths. With the beam incidence angle of 0-60 degrees, at intervals of 10 degrees, and inherent buildup of the 2D array (2 g/cm2), the array was irradiated and the readings of the central diode were compared with the measurement of thimble ionization chamber. Using a combined 30 cmx30 cmx30 cm phantom which consisted of solid water slabs on top and underlying the 2D array, with the diode detectors placed at 8 g/cm2 depth, measurements were taken for beam angles of 0 degrees-180 degrees at intervals of 10 degrees and compared with the calculation of treatment planning system (TPS) that pre-verified with ion chamber measuring.

RESULTSDifferences between the array detector and thimble chamber measurements were greater than 1% and 3.5% when the beam angle was larger than 30 degrees and 60 degrees, respectively. The measurements in the combined phantom were different from the calculation as high as 20% for 90 degrees beam angle, 2% at 90 degrees+/-5 degrees and less than 1% for all the other beam angles.

CONCLUSIONSThe 2D diode array is capable of being used in composite dose verification of IMRT when the beam angles of 90 degrees+/-5 degrees and 270 degrees+/-5 degrees are avoided.

Calibration ; Feasibility Studies ; Particle Accelerators ; Phantoms, Imaging ; Radiometry ; instrumentation ; Radiotherapy Dosage ; Radiotherapy Planning, Computer-Assisted ; Radiotherapy, Intensity-Modulated ; instrumentation ; methods

This article presents and discusses some special problems about the dose calibration of high-energy elections for Linear Accelerator according to the practice of the authors. Thus the paper explain the issues of this work, and clarify the wrong understanding of real work for the aim of attaining the rules of quality assurance in radiotherapy by WHO.
Calibration ; Particle Accelerators ; Radiotherapy Dosage ; Radiotherapy, High-Energy ; instrumentation ; methods

This article sum up the fourteen years experience of usage for a linear accelerator in our hospital. The goal is to ensure the secure usage and reduce the damage accidence and attain the rules of quality assurance in radiotherapy by WHO. The ultimate aim is to raise economic benefit and social benefit by linear accelerator.
Particle Accelerators ; Quality Control ; Radiosurgery ; instrumentation

Adult ; Breast Neoplasms ; radiotherapy ; surgery ; Cone-Beam Computed Tomography ; instrumentation ; methods ; Female ; Humans ; Mastectomy, Segmental ; Middle Aged ; Particle Accelerators ; Postoperative Period ; Radiotherapy Planning, Computer-Assisted ; instrumentation ; methods ; Respiration