Medical Imaging Cardiac CT Imaging Medical Image ProcessingComputer Assisted SurgeryRadiation Therapy
Osteoporosis ResearchDosimetry/Radiation Protection Dose Assessment/Dose Reduction Quality Assurance/Risk Management

 

Radiation Protection

The general radiation safety objective is to protect individuals, society and the environment from harm by radiological hazards. It prevents significant addition either to the risk to health or to the risk of other damage to which individuals, society and environment are exposed. It ensures that radiation exposure is kept below prescribed limits and as low as reasonably achievable. Radiation protection standards have been developed to prevent harmful effects of ionizing radiation by keeping exposures sufficiently low in normal conditions. In the event of any accident, safety provisions are planned and countermeasures outside the installation are prepared to minimize harm to individuals, populations and the environment.

ALARA Principle

There are actually three features in the system of dose limitation recommended by ICRP, namely justification, optimization, and dose limitation.

    1. Justification means that any proposed activity that may cause exposure to persons should yield a sufficient benefit to society to justify the risks incurred by the radiation exposure. This feature is based on the assumption that any radiation exposure, no matter how small, carries with it a certain level of risk that is proportional to the level of exposure. This hypothesis is known as the linear, non-threshold hypothesis, or LNT. An example of an activity that was considered unjustified was the now-discontinued practice of fitting shoes to people's feet using X-rays. The exposure resulting from this activity was considered to be unjustified, and the practice was discontinued.
    2. The second feature is optimization, which is also known as the practice of ALARA (As Low As is Reasonably Achievable). This means that the radiation exposures resulting from the practice must be reduced to the lowest level possible considering the cost of such a reduction in dose. Optimization is also based on the LNT.
      1. The third element is dose limitation. This involves setting upper limits on the dose that may be received by any member of the public from all man-made exposures. These limits are imposed by regulatory agencies. For example, if the dose limit is 1 mSv/yr for members of the public, then the constraint might be set at 0.3 mSv/yr. This may be viewed as that site's share of the allotted exposure of 1 mSv/yr to any member of the public, some of whom may be simultaneously exposed to radiation from several facilities. Each site will then optimize its doses as far below 0.3 mSv/yr as possible to ensure that the doses are ALARA.

Safety Analysis

The risk is taken to be the probability that a specified harmful effect will occur within a specified period. The aim of the specification of safety objectives is to reduce the risks associated with radiation to level considered tolerable by the appropriate national bodies, in the light of international practice. One of the purposes of safety analysis is to demonstrate that the specified safety objectives have been met. The safety analysis is carried out by probabilistic or deterministic methods, which are based on a selected set of scenarios (combination of events, sequences and processes). The selection must be made in such a way that the major contributors to risk are covered as far as reasonably achievable. The safety analysis determines if the types of risks to be considered have been reduced to tolerable levels. This should be performed using proven methods and with appropriate peer review.

Technical Safety

The technical safety objective is to take all reasonably practicable measures to prevent accidents and to minimize their consequences should they occur; to ensure with high levels of confidence that, for all possible accidents taken into account in the design of the installation, including those of very low probability, any radiological consequences would be minor and below prescribed limits; and to ensure that the likelihood of accidents with serious radiological consequences is extremely low.

Safety Management

Safety management is the term used for the measures required to ensure that an acceptable level of safety is maintained throughout the life of a radiological installation, including decommissioning. Management must ensure that its organization is well structured with clear lines of authority and communication and well defined responsibilities, and that its safety policies, requirements and procedures are established, understood and observed by all involved.

Human Factors

An important factor in safety management is the recognition of the influence of human behavior. The capabilities and limitations of human performance shall be taken into account at all stages. The possibility of the occurrence of human errors directly affecting safety needs to be recognized and the probability reduced to the minimum practically achievable. The effects of such errors must, where practicable, be eliminated or minimized by a systematic approach, in order to achieve a high tolerance of human errors. Additionally, functional requirements for personnel need to be defined and met through appropriate staff selection and training. In consequences, organizations engaged in activities important to safety shall ensure that there are sufficient numbers of adequately trained and authorized staff working in accordance with approved and validated procedures.

Radiation Protection Procedures

Specialist staff provide a comprehensive radiation protection service. The radiation protection staff establish written procedures for the control, guidance and protection of personnel, carry out routine monitoring of in-site radiological conditions, monitor the exposure of installation personnel to radiation, and also monitor releases of radioactivity. The radiation monitoring staff also have assigned responsibilities in the event of emergencies. Members of the operating staff may assume some of these radiation protection duties. Written procedures are issued as necessary to cover radiation protection functions.

  • Activities covered by the Radiation Protection Specialists at the Institute of Medical Physics
    • Survey of occupational exposure in accordance to national legislation (StrlSchV, RöV)
    • Implementation of latest developments in the field of radiation protection and dosimetry following international practice and national legislation (ICRP, ICRU, EURATOM, IEC, ISO,DIN, StrlSchV, RöV etc.)
    • Radiation monitoring and dosimetry
    • Emergency preparedness and response
    • Determination of medical exposure
    • Determination of Exposure of the public
    • Environmental monitoring and assessment of natural radiation using low-level gamma ray spectroscopy
    • Education, information and training in radiation protection for students, post-graduate students and staff.
    • Support of ongoing research projects regarding radiation protection and dosimetry.
    • Dosimetry, radiation treatment planning and radiation protection services for the Department of Radiation Oncology (Radiation Therapy Physics).