Interlock systems are very important in radiotherapy
because they enhance safety in the treatment area. The following are reasons
for installing interlock systems in the radiotherapy:
Interlock systems are divided into several types such as:
Door interlocking systems: They are designed in radiation treatment rooms and they are directly connected to the control console of the machine. They are used to inform the radiation technologists when it is safe to run a treatment after they have detected the last person out of the treatment room. They are also used to alert a radiation technologist when/if the treatment room door is opened or when someone accidentally attempts to enter when the treatment is ongoing.
All door interlock systems in radiotherapy should meet national and international safety standards. The entrance door should be fitted with two separate interlock switches which operate in a fail-to-safety manner. The two systems should operate in different ways, that is, in opposite modes, to avoid common-cause failures. Routine checks of the correct operations of the door interlock systems should be carried out by the radiation therapy technologist and their status should be recorded in the unit’s daily log. In case of any defects or deficiencies it should be reported and rectified before the next treatment.
How the status of door and radiation from an accelerator operates:
Machine interlocking systems: Machine interlock systems are designed to enhance safety and accuracy on a linear accelerator during a radiotherapy treatment. Purposes or reasons for installing machine interlocking systems includes:
Example of linear accelerator interlocks:
A Linear Accelerator Temperature
A Linear Accelerator Gas Pressure
A Linear Accelerator Water Level
Fire interlocking systems: Fire interlocking systems are mostly connected to a fire detection system that automatically runs a siren on detecting heat or smoke. The system can be connected to the linear accelerator where it will immediately abort the treatment or any ongoing process. The radiotherapy technologist should confirm that everything has been shut down, secure the safety of the patient and immediately call the emergency team.
1. Clifford E. DeMagri B.E.; Jason W. Sohn M.S.; Vernon Smith Ph.D.; Alex Perec B.S.; David A. Larson M.D., Ph.D.; Michael C. Schell Ph.D. 1996. Method of Developing an Interlock System for Linac-Based Stereotactic Radiosurgery. Retrieved from www.onlinelibrary.wiley.com on 10/1/2019 at 0540hrs
2. Argonne Physicist. Discussion of Linac Safety Systems. Retrieved from www.cse.anl.gov on 10/1/2019 at 0922hrs.
3. Frank Shields. 2018. Radiation Door Interlock System. Retrieved from www.frankshiels.com on 11/1/2019 at 0601 hrs.
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