DOCUMENT NO. : IKN-RS-SOP-12
All staffs who are occupationally exposed to ionizing radiation should be issued with and wear a personal radiation monitoring device from an approved personal radiation monitoring service. This would normally include all radiation workers that need to handle radioactivity or radioactive patients and might include other staffs such as receptionists etc. A direct-reading device, such as an electronic dosimeter, might also be worn for immediate indication of dose received. Local regulations or legislation might require monitoring of personnel in defined occupations such as nuclear medicine, irrespective of the likely annual dosage.
The Atomic Energy Licensing (Basic Safety Radiation Protection) Regulation 2010 requires the monitoring of personnel to be carried out on all personnel who work in controlled and supervised areas. For internal contamination issues, the Assessment of Occupational Exposure Due to Intake of Radionuclides Safety Guide RS-G-1.2 should be applied.
- Radiation Protection Officer (RPO)
- Radiation Workers
Each time work is carried out with radioactive materials
New Radiation Workers or Radiation Workers transferred from other institutions shall attend briefings on basic radiation safety in ionizing radiation conducted by RPO before working with ionizing radiations sources. The proof of the attendance shall be recorded in IKN-RS-F-059 Attendance Record for Radiation Safety Briefing
Personnel Monitoring Instruments for External Radiation
- The device is known as a dosimeter and it is used to measure radiation from sources outside the body. Such monitoring is required to be carried out on personnel who work with all types of radiation sources.
- The most commonly used dosimeters are TLD, OSL and direct reading dosimeters.
- The device must be worn at the place that represents whole-body exposure. In cases where certain parts of the body are thought to receive higher radiation exposure then that registered by the whole-body dosimeter, e.g. hands, an additional dosimeter should be worn specially to measure the exposure received by that part of the body. One example is the TLD ring used to measure the dose received by hand when handling gamma sources at a close distance.
- Refer to Personal Dosimeter Manual Guidelines IKN-NM-RS-SOP-14 for details.
- RPO shall inform the result of whole-body exposure and extremities to the respective radiation workers within 14 days after received from the third party.
- The respective radiation workers shall acknowledge the result within 30 days after received the result.
Personnel Monitoring Instrumentation for Internal Contamination
- Monitoring of internal contamination is required for personnel who work with open or unsealed radioactive sources or in places where contamination is confirmed to be present.
- Radioactive materials can enter the body through ingestion, inhalation or through the skin.
- There are two common methods used to determine internal contamination, namely bioassay and whole-body count
- Personnel contaminated externally are monitored using a portable radiation monitor or a fixed monitor called the hand and foot monitor. These monitoring instruments are usually stationed at the entrance of the contamination control barrier at the radioactive workplace. The instruments usually have an in-built alarm system that will trigger-off a warning if the contamination level exceeds the pre-set limit.
- All personnel working in radioactive workplaces must check for body contamination and ensure that their bodies are free of contamination before they leave their workplace. This is to control the spread of radioactive contamination.
Thyroid Uptake Screening and Bioassay
- Thyroid screening program is intended to monitor the personal intake of suspect contaminated with I-131 and I-125 only.
- Thyroid screening is used to determine the type, quantity, concentration or location of radioactive material in the human body.
- Accurate and timely information produced by the thyroid screening program provides assurance that the radiation protection program is working and demonstrates compliance with regulatory dose limits.
- Direct measurements can involve counting of the whole body or part of the body (neck for I-131) using external detectors or measurement of radioisotopes in samples of urine, faeces, hair, blood or sputum using a gamma or liquid scintillation counter.
- Refer to the Thyroid Uptake Operating Procedure IKN-NM-TY-SOP Thyroid Program Operating Procedures for details regarding measurement procedures.
- There are ‘As Low As Reasonably Achievable’ (ALARA) investigation levels for external occupational radiation exposure by nuclear medicine radiation staff as measured by personal dosimeters. Quarterly limit levels are 25% of the maximum limit according to The Atomic Energy Licensing (Basic Safety Radiation Protection) Regulations 2010 guideline.
- The RPO shall conduct clinical investigations, including the blood chromosome aberration test, on respective staffs, if necessary.
- If a radiation worker exceeds this level of dose in any quarter, the RPO will investigate and report the findings to the relevant personnel. A written notification will be sent to the respective staff.
- When the investigation shows that the staff member is likely to have received a dose equal to or above the investigative level, the respective staff would be notified.
- The regulatory authority might also need to be informed depending on the requirements of the relevant legislation.
- Atomic Energy Licensing (Basic Safety Radiation Protection) Regulations 2010.
- Nuclear Medicine Resource Manual, IAEA 2006.
- Radiation Protection in Nuclear Medicine, Radiation Protection Series Publication No. 14.2, ARPANSA 2008.
- Applying Radiation Safety Standards In Nuclear Medicine, Safety Reports Series No. 40 IAEA 2005.
This Standard Operating Procedure (SOP) was developed based on compilation of best available information, knowledge, field experience, and general practices to provide guidance to IKN staff in performing the activities defined herein, in a consistent and standardised manner.
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