Classification and common fault analysis of medical electron linear accelerators

     

 

 

I. Introduction

 

As one of the important equipment of modern medical radiation therapy, medical electron linear accelerator uses microwave electric field to accelerate electrons and produce high energy rays, which is used in remote external radiation therapy in human medical practice. With the continuous progress of medical technology, medical electron linear accelerators are playing an increasingly important role in the field of tumor therapy. The purpose of this paper is to discuss the classification and common fault analysis of medical electron linear accelerators, in order to provide reference for clinical application.

 

Ii. Classification of medical electron linear accelerators

 

Medical electron linear accelerators can be divided into various types according to different classification standards. The following are classified from three aspects: acceleration mode, energy level and use.

 

Accelerated mode classification

Medical electron linear accelerators can be divided into traveling wave accelerators and standing wave accelerators according to the different acceleration modes. The traveling wave acceleration method uses the microwave electric field to form traveling waves in the accelerator tube to accelerate the electrons. The standing wave acceleration method is to accelerate the electron by forming standing wave in the acceleration tube through microwave electric field. The two acceleration modes have their advantages and disadvantages. The traveling wave acceleration mode has the advantages of simple structure and high acceleration efficiency, but poor stability. The standing wave acceleration method has better stability, but the structure is complex and the cost is high.

 

Energy class classification

According to the voltage connected to the medical electron linear accelerator, it can be divided into low energy, medium energy and high energy three categories. The low energy medical electron linear accelerator is mainly suitable for the treatment of skin cancer and other superficial tumors. Medium energy medical electron linear accelerator can be used to treat some medium-depth tumors. High energy medical electron linear accelerator is mainly used to treat deep tumors. Medical electron linear accelerators with different energy levels have different indications and therapeutic effects in clinical applications.

 

Use classification

Medical electron linear accelerators can be divided into X-ray therapy machines and electron beam therapy machines according to different uses. X-ray therapy machine mainly uses high-energy X-rays for radiotherapy, with high penetration, low skin dose, high ray uniformity and other characteristics, suitable for the treatment of deep tumors. Electron beam therapy machine uses electron beam for radiation therapy, which has certain range characteristics and low penetration ability, and is suitable for treating superficial tumors.

 

3. Analysis of common faults of medical electron linear accelerator

 

Medical electron linear accelerator may fail due to various reasons during use. The following is an analysis of common faults from the low pressure part, high pressure part, mechanical part, water circulation system and vacuum system.

 

Low voltage partial fault

Low-voltage faults mainly include power supply faults, control circuit faults and so on. The power supply fault may be caused by short circuit, open circuit or unstable power supply voltage. Control circuit failure may be due to aging control components, damage or poor line contact and other reasons. The failure of the low-voltage part will cause the medical electron linear accelerator to not work properly or the performance will be degraded.

 

High voltage partial fault

The high voltage fault mainly includes the thyratron fault in the modulation cabinet, the pulse modulator fault and the high voltage pulse transformer fault. Thyratron failure may be caused by low gas pressure in the tube, overheating of the anode, or failure of the gate control circuit. The failure of the pulse modulator and the failure of the high-voltage pulse transformer may be caused by the aging of the components, damage or aging of the insulation. The failure of the high voltage part will cause the output voltage of the medical electron linear accelerator to be unstable or unable to output the high voltage pulse.

 

Partial mechanical failure

The mechanical faults mainly include the precision reduction of the head, frame, treatment bed and target moving parts, limit failure, locking and fixing parts loosening and falling off. These failures can be caused by wear, loosening or damage to mechanical parts. The mechanical failure will affect the accuracy and stability of the medical electron linear accelerator, and then affect the therapeutic effect.

 

The water circulation system is faulty

The water circulation system is the key to ensure the temperature stability of each electrical apparatus in medical electron linear accelerator. Water circulation system faults include bad circulating water quality, pipeline obstruction, high water temperature, or circulating pump failure. These faults can cause medical electron linear accelerators to become too hot or not work properly.

 

Vacuum system failure

The role of the vacuum system is to ensure that the accelerator tube, klystron and deflection magnetic field system maintain a high vacuum. Vacuum system failures include vacuum drop, air leakage, or vacuum pump failures. These faults will affect the performance and service life of medical electron linAC.

 

Iv. Conclusion

 

As one of the important equipment of modern medical radiation therapy, medical electron linear accelerator plays an important role in the field of tumor therapy. This paper introduces the classification and common fault analysis of medical electron linear accelerators, which can provide reference for clinical application. In practical application, the maintenance and maintenance of medical electron linear accelerator should be strengthened, timely detection and troubleshooting, to ensure the normal operation of the equipment and treatment effect. At the same time, with the continuous progress and development of medical technology, medical electron linear accelerators will be more intelligent, efficient and safe.