Environmental Protection

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Three; 3 questions out of the 35 questions in the Radiation Protection and Quality Assurance content area come from the Environmental Protection sub-topic.

Radioactive Materials

When the nucleus of a radioactive nuclide spontaneously gives up its extra energy, this energy is known as ionizing radiation. Ionizing radiation may take the form of alpha particles, beta particles, or gamma rays, or x-rays. The phenomenon of emitting the radiation is called radioactive decay. The sources of radioactive materials

  1. Nuclear reactors
  2. Radiotherapy installations using the radioisotope machines
  3. Nuclear medicine department in a hospital
  4. Research institutes using the radioisotopes
  5. Inherent radiation sources in the earth crust.

All of the above mentioned sources are affecting the environment in certain way; the ways will briefly discussed below.

Nuclear Reactors:

Nuclear reactors using the radioactive materials such as uranium, thorium, plutonium for generating the power production r purposes, nuclear bomb production and other research purposes. When they are using like this plenty of advantages are there however, that much of hazards is also there. If, they are not handled or disposed in secured places this things will affect the environment in potential way. In the Second World War shows the effect of radiation to this world through the explosion of atom bomb. These things will also lead to an environmental hazard if it happens again for several years.

Radiotherapy and Nuclear Medicine Department in a Hospital:

Radiotherapy and Nuclear medicine department are playing a vital role in cancer treatment and its diagnosis. For the treatment purposes radioisotopes are used in general in developing countries in addition to that linear accelerators also in use. Because of this greater use of the radioactive it should special attention is required in maintaining the import, export, and disposal of these sources. In all the country the respective government body is taking the steps to monitor that. However, these sources are causing some environmental effect when they are using for treatment.

Inherent Radiation Sources in Earth Crust:

The inherent radiation sources in earth crust are the other major factor in causing the environmental pollution. Because the radiation is level is different for different parts of the world. Especially kerala costal an area in India is having the natural uranium sources this place is having the natural background radiation than other parts of the country.

The environmental protection can only stabilized or bring to the normal position or in control by reduction in the usage of radioactive materials in day today life in the world.

References:

  1. http://www.nj.gov

Chemotherapy

Our cells in our body grow and die in a very well controlled way. In event of cancer this controlled mechanism becomes abrupt.  Chemotherapy is drug therapy that can kill these cells or stop them from multiplying. However, it can also harm healthy cells, which causes side effects. During the chemotherapy some patients may have no side effects or just a few. The side effects will be depending on the dose quantity and adaptability of the drug.  Side effects are different for different drugs but, usually side effects are nausea, vomiting, tiredness, pain and hair loss. Healthy cells usually recover after chemotherapy, so most side effects gradually go away. The course of therapy will depend on the cancer type, the chemotherapy drugs used, the treatment goal and how the patient body responds. Treatment cycles will vary sometimes every day, every week or every month. Gap between the cycles also recommended, so that your body has a chance to build new healthy cells. The mode of delivery the drug in patient’s body might be by mouth, in a shot or intravenously.

The majority of chemotherapeutic drugs can be separated in to alkylating agents, antimetabolites, anthracyclines, plant alkaloids, topoisomerase inhibitors, and other antitumor agents.  All of these drugs affect the cancer cell division or DNA synthesis and function in some way. Some newer agents do not directly interfere with DNA. These include monoclonal antibodies and the new tyrosine kinase inhibitors, which directly targets a molecular abnormality in certain types of cancer (Gastrointestinal stromal tumours). These are examples of targeted therapies. In addition, some drugs that modify tumour cell behaviour without directly attacking those cells may be used. Hormone treatments fall into this classification.

Dosage of chemotherapy can be vary for different type of cancer .  If the dose is too low, it will be ineffective against the tumour, whereas, at excessive doses, the toxicity (side-effects, tropenia) will be unbearable to the patient. This has led to the formation of detailed "dosing schemes" in most hospitals, which give guidance on the correct dose and adjustment in case of toxicity. In immunotherapy, they are in code used in smaller dosages than in the treatment of malignant diseases. In most cases, the dose is adjusted for the patient's body surface area, a measure that correlates with blood volume. The BSA is usually calculated with a mathematical formula using a patient's weight and height, rather than by direct measurement. 

Questions:

1. The drugs for the chemotherapy will vary for different tumour or same?

  1. It will vary
  2. It will not vary
  3. Both
  4. None of these

Answer:

 1. It will vary.

References: 

  1. http://www.cancerquest.org
  2. http://www.nlm.nih.gov
  3. http://en.wikipedia.org

Handling & disposal

        The basic approaches used in handling and disposal of radioactive wastes are;

  1. Delay and decay
  2. Dilute and disperse
  3. Concentrate and contain

Delay and decay:

It is based on the fact that radionuclides lose their radioactivity through decay, and this fact maybe utilized in the treatment not only of intermediate and high level solid, liquid and gaseous wastes but in some cases also in that of low level wastes. The aim is to ease problems in subsequent handling or to lessen risks of releases to the environment, taking advantage of the decay of some radionuclides particularly those having short half-lives with the passage of time. The principle is especially useful for those installations where a substantial reduction in the activity level of a waste stream can be achieved by delaying discharge of effluents for a few days.

Dilute and disperse:

The principle of dilution and dispersion is based on the assumption that the environment has a finite capacity for dilution of radionuclides to an innocuous level. The application of this principle requires an understanding of the behaviour of radioactive materials in the environment and of the ways in which the released radionuclides, particularly those that are considered to be critical, may lead later to the exposure of man. It is especially important to take into consideration environmental processes which may cause re-concentration of radionuclides.

The above figure Radioactive wastes containment

Concentrate and contain:

The principle of concentration and containment derives from the concept that the majority of the radioactivity generated in nuclear programs must be kept in isolation from the human environment. Since some radionuclides take a long time to decay to innocuous level, some wastes must be contained for extended period of time.

The principle is invoked in techniques for air and gas cleaning the treatment of liquid wastes by scavenging and precipitation; ion-exchange and evaporation; the treatment of low level, solid wastes by incineration, baling and packaging the treatment of intermediate level solid and liquid wastes by in-solubilisation in asphalt; conversion of high level solid and liquid wastes to insoluble solids b high temperature calcinations or incorporation in glass; tank storage of intermediate and high level liquid wastes; storage of solid wastes in vaults or caverns; and disposal of solid and liquid wastes in deep geological formations.

Questions:

  1. Delay and decay method is used for
  1. Intermediate level wastes
  2. Short half-life radionuclides
  3. High level wastes
  4. All

Answer:

  1. b) Short half-life radionuclides.

References:

  1. The Textbook of Radiological Safety, first edition, by Dr. k.Thayalan.

Toxic and hazardous materials

According to Environmental Protection Agency (EPA), any waste that is harmful or fatal to living organisms when inhaled, swallowed or absorbed is referred to as toxic waste. While hazardous waste is any waste that meets one or more of the following waste characteristics:

  • Corrosivity. Corrosive wastes are liquids capable of corroding metal containers. Example; battery acid.
  • Reactivity. Reactive wastes are those that can cause explosions when heated, mixed with water or compressed.
  • Ignitability. Ignitable wastes are wastes that have flash points of less than 60 degrees Celsius. They are very combustible and can easily cause fire.
  • Toxicity. Toxic materials are poisonous by-products as a result of manufacturing industries, construction, automotive, farming, laboratories and hospitals.

Toxic materials can be man-made or naturally occurring in the environment. They may contain chemicals, radiation, heavy metals or dangerous pathogens. Not all hazardous materials are considered toxic.

In radiotherapy, information about hazardous materials is found in Material Safety Data Sheets, it includes the name of the product, information about the product’s risks and measures that must be taken when a person has been exposed to some risk relating to the product. It also contains information about the procedures for using, handling, disposing and storing the particular product.

A sample of Material Safety Data Sheet

Items such as sharps and bed linens that are contaminated with blood or other bodily fluids are considered biohazardous medical waste. Biohazardous materials place patients, staff and visitors at risk for exposure to pathogens transmitted with bodily fluids. Therefore careful handling and disposal of all hazardous materials protects the staff, patients and visitors from harm. This can be achieved by implementing the following safety measures:

  • Placement of impervious red containers in all patients’ rooms to collect disposable contaminated sharps.
  • Proper handwashing
  • Use of personal protective equipment.
  • Use of single patient disposal supplies and equipment.

Flammable and combustible materials such as medical gases should be designed, constructed and according to Occupational Safety and Health Administration regulations. Emergency shut off valves are mandated for centralized medical gas delivery system in the case of an emergency. All synthetic fibers and fabrics should be kept away from oxygen canisters because they can create static electricity.

Radiation safety is based on the three safety principles; time, distance and shielding. Time of the radiation exposure is the most important factor out of the three major radiation safety principles. A radiation worker will receive more radiation exposure the more time he spends around a radioactive source. Use of radiation monitoring devices like ionization chambers, gamma zone monitors, Geiger- Muller (GM) Counter, neutron detectors, personal equipment like film badges and thermoluminescent dosimeter (TLD) may be beneficial in detecting low level radiation hence reducing the exposure time.

The second principle of radiation safety is maintaining a safe distance from the radioactive source which is based on the inverse square law, whereby the greater the distance, the less the radiation received by a factor of 1 over distance squared. The third principle is shielding or protecting the radiation worker from ionizing radiation with protective devices or shields. The thickness of shielding materials required to protect a radiation worker is determined by their half-value layer (HVL) and tenth-value layer (TVL) which attenuates the intensity of the incident radiation beam to half and one-tenth of its original values respectively. The gamma and x-ray radiation are shielded with high atomic (z) number materials. Use of lead aprons and gloves is recommended when one is working near the radiation source.

In brachytherapy, where high radiation doses are delivered, the following precautions should be put into considerations to protect the staff and visitors from radiation exposure:

  • The patient receiving the treatment should be put in a private room.
  • No activity should be taking place outside the brachytherapy room when the radiation is on.
  • Minimizing the duration of time that health care providers are in the patient’s room to deliver care and services to the patient.
  • Educating the family members and the visitors about their need to limit their visits to at least less than an hour, to stay at least 6 feet away from the patient and not to enter into the room if one is pregnant.
  • Initiation of complete bed rest for the patient until the treatment is discontinued.

REFERENCES

1. Abhishek Purkayastha, Department of Radiation Oncology, Command Hospital, India. (April 2018). Occupational Hazards for Radiotherapy Technicians in a Radiation Oncology Unit. Retrieved from https://googleweblight.com/i?=https://www.omicsonline.org/open-access/occupational-hazards-for-radiotherapy-technicians-in-a-radiation-oncology-unit-2329-6879-1000e115-101004.html&hl=en-KE

on 26/11/2018 0900hrs. 

2. NCLEX-RN. (2018). Handling Hazardous and Infectious Materials. Retrieved from https://googleweblight.com/i?=https://www.registerednursing.org/nclex/handling-hazardous-infectious-materials/hl=en-KE on 25/11/2018 1400hrs.  

3.Wikipedia. (2018). Toxic waste.

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