RESUMEN
We analyzed a number of cases about the Linac troubles in our hospital and have examined the effect of preventive maintenance with Weibull analysis and exponential distribution from April 2001 to March 2012. The total failure by irradiation disabled was 1, 192. (1) Medical linear accelerator (MLC) system was 24.0%, (2) radiation dosimetry system 13.1%, and the (3) cooling-water system was 26.5%. It accounts for 63.6% of the total number of failures. Each parameter value m, which means the shape parameter, and the failure period expectancy of parts µ were (1) 1.21, 1.46/3.9, 3.8 years. 3.7, 3.6 years. (2) 2.84, 1.59/6.6, 4.3 years. 6.7, 5.9 years. (3) 5.12, 4.16/6.1, 8.5 years. 6.1, 8.5 years. Each shape parameter was m>1. It is believed that they are in the worn-out failure period. To prevent failure, MLC performance should be overhauled once every 3 years and a cooling unit should be overhauled once every 7 years. Preventive maintenance is useful in assessing the failure of radiation therapy equipment. In a radiation dosimetry part, you can make a preemptive move before the failure by changing the monitor's dosimeter board with a new part from the repairs stockpiled every 6 months for maintenance.
Asunto(s)
Análisis de Falla de Equipo/métodos , Falla de Equipo , Aceleradores de Partículas , Mantenimiento , Reproducibilidad de los Resultados , Factores de TiempoRESUMEN
We developed software for estimating exposure doses and radiation exposure regions in cardiac catheterization inspection. In the software, the back of a thoracic phantom were divided into a total of 21 square blocks with a width of 30 degrees. Furthermore, we developed a system with which reference air kerma is distributed to each of the above blocks in accordance with the distribution ratio calculated from the data obtained by the system, and the calculation results are displayed. Coronary angiography was performed using thoracic phantoms, and actual measurements were obtained using a fluoroglass dosimeter. The calculated results obtained using the software were compared to the measured results. An almost identical tendency was seen, and the radiation regions of the top three estimated exposure doses were successfully estimated. Radiation region estimation using this software is affected by exposure time as one of its properties. This software enables estimating radiation exposure regions and exposure doses.
Asunto(s)
Cateterismo Cardíaco , Dosis de Radiación , Diseño de Software , Angiografía Coronaria , Humanos , Tórax/efectos de la radiaciónRESUMEN
The radiation field shape for cardiac catheterization has changed from being circular to being rectangular with the spread of flat-panel detector systems. A rectangular radiation field provides a wide fluoroscopy field to the four corners of a subject area; however, in cardiac catheterization, there is not much usable information around the four corners at several angles, and this tends to be regarded as a meaningless radiation exposure. Hence, overlap of radiation fields has been of concern recently. The authors changed field sizes/fluoroscopy angles and examined entrance dose rates to study radiation field shapes and configurations of radiation exposure to patients, and they discussed a radiation exposure reduction method. In measurements of phantom entrance dose rates, we considered right anterior oblique (RAO) directions, cranial (CRA) directions and RAO-CRA directions and found that entrance dose rates rose considerably, particularly at the RAO-CRA. In the study of radiation field overlap, we discuss radiation field shapes (rectangular/circular) as well as angles. In the RAO-CRA directions, differences occurred in angles of non-overlapping radiation field by differences in radiation field shapes. For RAO-CRA, compared with the RAO and CRA directions, entrance dose rates increased with an increase in angle. When convenience in clinics is considered, the utilization frequency of the four corners of a rectangular field is low. When one considers the increases in radiation exposure caused by radiation field overlap, it is more effective to use circular radiation fields.
Asunto(s)
Cateterismo Cardíaco/instrumentación , Fluoroscopía/instrumentación , Exposición a Riesgos Ambientales/prevención & control , Fantasmas de Imagen , Dosis de Radiación , Cráneo/efectos de la radiaciónRESUMEN
Angiographic cone-beam CT, called DynaCT by SIEMENS, is a 3D imaging tool reconstructed from projection data by a rotational C-arm with a flat panel detector. It can visualize low-contrast objects such as soft tissue or small vessels as well as high-contrast structures such as enhanced vessels or bone. We need to understand its image characteristics and dose distribution during 200 degree rotation around a patient. In this research, we evaluated fundamental characteristics and dose effectiveness for optimized clinical images. DynaCT, including soft tissue information and isochronal voxel data along the z-axis, could provide enough CT-like image quality for IVR use. In addition, evaluation of accumulated dose distribution helped us to predict and avoid the occurrence of radiodermatitis. Thus, DynaCT is useful as a support and navigation tool for IVR.
Asunto(s)
Angiografía , Tomografía Computarizada de Haz Cónico , Angiografía/instrumentación , Angiografía/métodos , Tomografía Computarizada de Haz Cónico/instrumentación , Tomografía Computarizada de Haz Cónico/métodos , Fantasmas de Imagen , Radiografía Intervencional/instrumentación , Radiografía Intervencional/métodos , Planificación de la Radioterapia Asistida por ComputadorRESUMEN
A variety of radiation hazards resulting from interventional radiology (IVR) have been reported in recent years. Particularly affected are the skin and the crystalline lens, with their high radiation sensitivity. During neurological interventions, the radiological technologist should consider decreasing radiation exposure. We found exposure projections where the exposure dose became a radiation hazard for the crystalline lens, and examined an efficient method of cover for the exposure projections used for neurological interventions. The exposure projection for maximum crystalline lens radiation exposure was a lateral projection. In the crystalline lens the maximum exposure to radiation was on the X-ray tube side. The method of defense adopted was that of installing a lead plate of the appropriate shape on the surface of the X-ray tube collimator. In other exposure projections, this cover did not become a redundant shadow. With the cover that was created, the X-ray side crystalline lens lateral projection could be defended effectively.
Asunto(s)
Arterias Cerebrales/diagnóstico por imagen , Cristalino/efectos de la radiación , Protección Radiológica/instrumentación , Radiología Intervencionista , Humanos , RadiografíaRESUMEN
The management of apparatus for diagnostic imaging is an important job for radiological technologists. In the last 10 years we have encountered 2227 malfunctions in 3652 days. We detected 163 cases at the initial check-up, which accounted for 7.3% of total cases. By performing an initial check-up, we detected one malfunction every 21 days and were able to keep the effects of mishaps to a minimum, prevent accidents, and obtain stable-quality images.