How Can Radiation Be Controlled And Safely Used In Medicine

24.06.2020

The World Nuclear Organization informs that the use of radiopharmaceuticals for diagnosis has a growth rate of more than 10%annually. In addition, 7.5 million cancer patients globally were receiving radiation-based treatment by 2013.

The flip side is that ionizing radiation in health care is the single largest artificial source of radiation exposure for patients, healthcare workers, and the population in general, according to WHO (World Health Organization).

Who Are Is at Risk of Radiation Exposure?

The International Atomic Energy Agency (IAEA) in its 2018 safety guide explains that the use of diagnostic and/or therapeutic radiation poses three levels of exposure threats:

  • Medical exposure of the patient to radiation, both for diagnosis and treatment. The use of radiation for diagnosis started way back with Roentgen’s discovery of the x-ray in 1895. It has since increased with an array of diagnostic procedures today using radiation.

Computed tomography (CT), fluoroscopy, mammography, nuclear medicine, positron emission tomography (PET). etc. are all medical diagnostic procedures that use ionizing radiation.

The maximum application of radiation therapy is in cancer treatment.

  • Occupational exposure to radiation includes healthcare workers involved, as also radiology equipment suppliers and maintenance staff. Students and apprentices learning to use radiological procedures or equipment also form a part of those exposed to radiation due to their occupation.
  • Public exposure of family members and other visitors who visit a patient, such as a cancer patient, undergoing radionuclide therapy.

Reducing unnecessary radiation exposures even while optimizing the use of radiation for diagnostic and therapeutic purposes emerges as a critical need, therefore.

Risks in the medical use of radiation

WHO outlines the following risks in the medical use of radiation for diagnosis and treatment:

  • If the radiation dose exceeds a specified threshold, it can induce the killing of cells. That can be severe enough to weaken the functionality of organs and tissues not directly exposed to radiation.

The technical term in medical parlance for this adverse effect is “tissue reactions”.

  • Then there is the stochastic effect, which allows a cell to maintain its reproducibility and resurrect cancer in a patient after a period of dormancy. It may also pass on the carcinogenic propensity to the offspring.
  • Radiation exposure in early life, including prenatal radiation exposure, can lead to several adverse effects, including cognitive impairment.
  • Radiation exposure is not a threat for the majority of healthcare workers, and other allied individuals such as suppliers and maintenance personnel. However, those working in radiology, interventional radiologists, and dental hygienists do get exposed to low doses of radiation on a regular basis.

These risks make radiation protection in medicine a critical factor in optimizing the benefits of radiation-based diagnosis and therapies.

General Safety Principles for Exposure to Radiation in a Medical Situation

The IAEA presents a detailed guideline to facilitate safety against radiation at all three levels: of the patient, of healthcare workers, and of visitors. Both the IAEA and WHO underscore the following general safety principles for the optimization of protection in radiotherapy:

The Justification Principle

  • A risk-benefit analysis must guide the use of diagnostic and therapeutic radiology. The benefits of radiation exposure of the patient, health workers and other allied professionals, and visitors must outweigh the harmful effects of radiation exposure.

Optimization of Protection and Safety

  • Measures to ensure optimal safety at all three levels must always accompany the medical use of radiation for diagnosis and therapy.
  • Protection and safety optimization strategies must include emergency preparedness to address accidental and unintended exposure to radiation.

Applying Dose Limits

Diagnostic reference levels (DRLs) determine the dose limitation levels. Professional bodies in conjunction with the relevant health authority and the regulatory agency formulate DRLs.

These bodies also review DRLs periodically and modify them as per need. DRLs reflect an adjustment between essential stability and the long-term modifications in the distribution of dosage.

Internationally accepted DRLs exist for calculating dose limitations at all three levels.

Safety Procedures for Diagnostic Radiology and Interventional Radiology

  • Radiology-based imaging, for example, needs to be avoided when clinical assessment or non-radiation based imaging is adequate for diagnosis.

Ultrasonography (USG) and magnetic resonance imaging (MRI), for example, are medical imaging techniques that do not use ionizing radiation.

  • The main purpose of radiation therapy is to administer the prescribed dose of ionizing radiation to the target volume with minimal exposure to healthy tissues.

Using predictive biological models of tumor control probability (TCP) and normal tissue control possibility (NTCP) at the treatment planning stage for individual patients is the recommended method for optimizing the benefits of radiation therapy.

  • Optimization of radiation therapy outcome needs a multidisciplinary team involving a medical physicist, a radiological medical practitioner, a radiation technologist, and others, in addition to the oncologist.

Challenges in Radiation Safety Optimization

Standards codified in the International Radiation Basic Safety Standards (BSS) are not legally binding in many countries of the world. That allows considerable discrepancies and gaps in the radiation protection culture to exist across healthcare organizations and countries.

In Conclusion

While the contribution of radiation in medical diagnosis and therapy is undeniable, there are safety lapses that need affirmative actions on the part of all the stakeholders concerned. An improved radiation safety culture needs the proactive participation of lawmakers, regulatory authorities, equipment manufacturers, patient groups, and healthcare professionals.

How Can Radiation Be Controlled And Safely Used In Medicine

How do medical staff protect themselves from radiation?

Radiation protection for medical staff works at different levels. At the individual level, they need to adhere to radiation safety practices, for which they need adequate education and training.

The other contributing factors are:

  • Radiology units and equipment must maintain the international safety standards of distance, shielding, and time.
  • International diagnostic reference levels (DRLs) need to be followed to limit the level of exposure of medical staff.
  • Each medical staff with radiation exposure possibility must have protective gear.

What unit of radiation damage is most commonly used in medicine?

The System International (SI) is a commonly used radiation measure in the international community, though conventional measures are still prevalent in the U.S. Also, scientists use different measures depending upon the context. For radiation therapy, the common unit to measure the absorbed radiation dose is the SI Gy. However, in the U.S. the conventional rad is also in use. On SI Gy is equal to 100 rad. Rad stands for radiation absorbed dose. The energy received through radiation deposits in the tissues of the person receiving the therapy. Radiation absorbed dose means the amount of energy deposited per unit weight of human tissues. The unit to measure the biological risk of unintended radiation exposure is the SI Sv, though in the U.S. the conventional rem is also used. One SI Sv is equal to 100 rem. Scientists have assigned numbers, known as the Quality Factors (Q), to each of the four types of ionizing radiation: the alpha and beta particles, gamma rays, and x-rays. The ability of the type to transfer energy to the cells of the body is the basis of each Q. Scientists calculate the biological risk by multiplying the rad by the Q of the radiation type involved.

What material can block radiation?

Several inches of concrete and any dense material like lead can also block radiation. Traditionally, lead has been in use to make protective gear against radiation exposure. However, now lead-composites and other heavy materials such as antimony, bismuth, tin, and tungsten also get used to manufacture radiation shielding gear.

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