Half-life is a term used to express the rate at which a given radionuclide gives up its radioactivity. With time, the radioactivity comes down, but not the mass. More or less, the mass of the radioactive material remains the same even after very many years of radioactive decay. And Specific Activity is the term used to express the quantity of radioactivity per gram of a material.
Take an example of a source of Cobalt-60 (Co-60). The source is generally used in gamma irradiators/chambers used in industry and medicine. The half life of Co-60 is 5.27 years. This means, in 5.27 years the radioactivity of the source reduces by one-half. The mass of the source remains the same. A typical irradiator source of strength 1000 Curie (Similar to sources recovered in Mayapuri, Delhi) will give gamma radiation dose rate of 13.25 Gray per hour. After say, 25 years of decay, the dose rate of the source will reduce to 0.4 Gray per hour. If some one is exposed to this source (the so-called decayed source) for about 10 hours, the person is likely to get dose of 4 Gray which is in the range of Lethal dose -50 (LD-50).
Lethal dose – 50/60 means, if 100 people are exposed to the dose of 4 to 5 Gray, 50 persons will die in 60 days’ time after the exposure.
That is precisely the reason why the “decayed sources” just lying in some cup-boards in laboratories or in hospitals for over 25 to 30 years can still be dangerous and can deliver fatal doses if the sources are not properly shielded, or not handled with care. The decayed sources should be disposed off by strictly following the procedure suggested by the national regulators. In India, the regulator is Atomic Energy Regulatory Board (AERB), located at Anushaktinagar, Mumbai, 400094.
Handle radioactivity carefully and not fearfully.
Monday, January 10, 2011
Handle radioactivity carefully and not fearfully
Half-life is a term used to express the rate at which a given radionuclide gives up its radioactivity. With time, the radioactivity comes down, but not the mass. More or less, the mass of the radioactive material remains the same even after very many years of radioactive decay. And Specific Activity is the term used to express the quantity of radioactivity per gram of a material.
Take an example of a source of Cobalt-60 (Co-60). The source is generally used in gamma irradiators/chambers used in industry and medicine. The half life of Co-60 is 5.27 years. This means, in 5.27 years the radioactivity of the source reduces by one-half. The mass of the source remains the same. A typical irradiator source of strength 1000 Curie (Similar to sources recovered in Mayapuri, Delhi) will give gamma radiation dose rate of 13.25 Gray per hour. After say, 25 years of decay, the dose rate of the source will reduce to 0.4 Gray per hour. If some one is exposed to this source (the so-called decayed source) for about 10 hours, the person is likely to get dose of 4 Gray which is in the range of Lethal dose -50 (LD-50).
Lethal dose – 50/60 means, if 100 people are exposed to the dose of 4 to 5 Gray, 50 persons will die in 60 days’ time after the exposure.
That is precisely the reason why the “decayed sources” just lying in some cup-boards in laboratories or in hospitals for over 25 to 30 years can still be dangerous and can deliver fatal doses if the sources are not properly shielded, or not handled with care. The decayed sources should be disposed off by strictly following the procedure suggested by the national regulators. In India, the regulator is Atomic Energy Regulatory Board (AERB), located at Anushaktinagar, Mumbai, 400094.
Handle radioactivity carefully and not fearfully.
Take an example of a source of Cobalt-60 (Co-60). The source is generally used in gamma irradiators/chambers used in industry and medicine. The half life of Co-60 is 5.27 years. This means, in 5.27 years the radioactivity of the source reduces by one-half. The mass of the source remains the same. A typical irradiator source of strength 1000 Curie (Similar to sources recovered in Mayapuri, Delhi) will give gamma radiation dose rate of 13.25 Gray per hour. After say, 25 years of decay, the dose rate of the source will reduce to 0.4 Gray per hour. If some one is exposed to this source (the so-called decayed source) for about 10 hours, the person is likely to get dose of 4 Gray which is in the range of Lethal dose -50 (LD-50).
Lethal dose – 50/60 means, if 100 people are exposed to the dose of 4 to 5 Gray, 50 persons will die in 60 days’ time after the exposure.
That is precisely the reason why the “decayed sources” just lying in some cup-boards in laboratories or in hospitals for over 25 to 30 years can still be dangerous and can deliver fatal doses if the sources are not properly shielded, or not handled with care. The decayed sources should be disposed off by strictly following the procedure suggested by the national regulators. In India, the regulator is Atomic Energy Regulatory Board (AERB), located at Anushaktinagar, Mumbai, 400094.
Handle radioactivity carefully and not fearfully.
Thursday, December 30, 2010
Over-exposures in medical applications of radiation
It is now well known that in radiation therapy, high doses are given to the affected tissues/organs so as to kill the diseased tissues. It is expected that the physician decides and optimizes the dose requirement in consultation with a radiation physicist to ensure radiation protection of the patient. A recent report on the above topic in the Times of India is a matter of grave concern. During medical procedures in US, three patients were given over doses which resulted in organ failures crippling the patients.
Highly collimated radiation beams are used to treat tiny tumors in sensitive organs such as brain or in spinal cord. The collimated beam ensures protection of healthy surrounding tissues. However, any malfunctioning of the system, mismatch of electronic components and improper use of the equipments used in medical diagnosis (X-rays and CT scans) and external radiation beam therapy sources (medical accelerators and Co-60 sources) may result in leakage of the radiation and exposure of other healthy tissues which may ultimately result in long- term severe health problems.
Stringent regulations and quality assurance programs are absolutely necessary for the protection of the patients. The medical and paramedical staff should be well trained in all aspects of radiation protection. Medical procedures involving radiation should be recommended only if the benefits outweigh risks of the radiation exposure.
Highly collimated radiation beams are used to treat tiny tumors in sensitive organs such as brain or in spinal cord. The collimated beam ensures protection of healthy surrounding tissues. However, any malfunctioning of the system, mismatch of electronic components and improper use of the equipments used in medical diagnosis (X-rays and CT scans) and external radiation beam therapy sources (medical accelerators and Co-60 sources) may result in leakage of the radiation and exposure of other healthy tissues which may ultimately result in long- term severe health problems.
Stringent regulations and quality assurance programs are absolutely necessary for the protection of the patients. The medical and paramedical staff should be well trained in all aspects of radiation protection. Medical procedures involving radiation should be recommended only if the benefits outweigh risks of the radiation exposure.
Tuesday, December 7, 2010
Exposure to EMF radiations from mobile phones and towers
The health effect Electro-Magnetic Frequency (EMF) radiation from the towers/mobile phones is of great concern. As reported, the probability of health effects is about 5 times higher in case of children and teenagers. Pregnant women should also be protected from the exposures so that the fetus is not exposed.
It is reported that about 50% of Indian population are using mobile phones! There are several thousands of transmission towers mushrooming all over the country. The convenience of mobile phone in passing on messages is undisputed. But it is over-used and unregulated. That is the concern.
Since last three years, I have been fighting a lone battle to create public awareness about the issue. I have written many posts in my blog site http://radsafe.blogspot.com. I also have written a 11 page write-up on the safety concerns and protection standards for EMF radiation in my web site www.radsafetyinfo.com. As a radiation protection professional, in my anxiety to sensitize the authorities, I have written letters to Municipal Commissioners of Mumbai and Navi Mumbai, Mayer of Navi Mumbai and Maharashtra Health Minister highlighting the public health concerns due to the EM radiation pollution and the possible health effects from the excessive usage of mobile phones, and exposure to EMF radiation from the towers. I have copies of the communications.
I doubt whether India has a separate regulator to ensure safety from the EMF radiation exposures. It was suggested that BARC/AERB should start monitoring the EMF density in different locations to ensure see compliance with the available international standards.
Somehow, nothing happened. I felt at that time that the telecom lobby is too strong and it is very difficult to make the government take action on the issue. However, about 6 month's back, Maharashtra Government has formed a committee to look into the matter. It is heartening to note that the newspapers like Times of India and Mumbai Mirror have started realizing the impending public health disaster from excessive usage of mobile phones and EMF emissions from the towers. It is already late. Better late than never.
It is reported that about 50% of Indian population are using mobile phones! There are several thousands of transmission towers mushrooming all over the country. The convenience of mobile phone in passing on messages is undisputed. But it is over-used and unregulated. That is the concern.
Since last three years, I have been fighting a lone battle to create public awareness about the issue. I have written many posts in my blog site http://radsafe.blogspot.com. I also have written a 11 page write-up on the safety concerns and protection standards for EMF radiation in my web site www.radsafetyinfo.com. As a radiation protection professional, in my anxiety to sensitize the authorities, I have written letters to Municipal Commissioners of Mumbai and Navi Mumbai, Mayer of Navi Mumbai and Maharashtra Health Minister highlighting the public health concerns due to the EM radiation pollution and the possible health effects from the excessive usage of mobile phones, and exposure to EMF radiation from the towers. I have copies of the communications.
I doubt whether India has a separate regulator to ensure safety from the EMF radiation exposures. It was suggested that BARC/AERB should start monitoring the EMF density in different locations to ensure see compliance with the available international standards.
Somehow, nothing happened. I felt at that time that the telecom lobby is too strong and it is very difficult to make the government take action on the issue. However, about 6 month's back, Maharashtra Government has formed a committee to look into the matter. It is heartening to note that the newspapers like Times of India and Mumbai Mirror have started realizing the impending public health disaster from excessive usage of mobile phones and EMF emissions from the towers. It is already late. Better late than never.
Monday, November 22, 2010
The International Nuclear and Radiological Event Scale (INES): 20 Years of Nuclear Communication
The International Atomic Energy Agency (IAEA) and the OECD Nuclear Energy Agency (NEA) are celebrating the 20th anniversary of the International Nuclear and Radiological Event Scale (INES). The scale has sound technical background.
Jointly developed by the IAEA and the NEA in 1990, in the aftermath of the Chernobyl accident, the INES is to help nuclear and radiation safety authorities and the nuclear industry worldwide to rate nuclear and radiological events and to communicate their safety significance to the general public, the media and the technical community. The INES was initially used to classify events at nuclear power plants only. It was subsequently extended to rate events occurring in any nuclear facility and during the transport and storage of radioactive material and covers events related to the overexposure of workers.
Since its inception, it has been adopted in 69 countries, and an increasing number of countries have expressed their interest in using INES. Over the years, national nuclear safety authorities have made growing use of INES, while the public and the media have become more familiar with the scale and its significance.
Jointly developed by the IAEA and the NEA in 1990, in the aftermath of the Chernobyl accident, the INES is to help nuclear and radiation safety authorities and the nuclear industry worldwide to rate nuclear and radiological events and to communicate their safety significance to the general public, the media and the technical community. The INES was initially used to classify events at nuclear power plants only. It was subsequently extended to rate events occurring in any nuclear facility and during the transport and storage of radioactive material and covers events related to the overexposure of workers.
Since its inception, it has been adopted in 69 countries, and an increasing number of countries have expressed their interest in using INES. Over the years, national nuclear safety authorities have made growing use of INES, while the public and the media have become more familiar with the scale and its significance.
Saturday, November 20, 2010
Irradiation to Ensure the Safety and Quality of Prepared Meals
This publication (STI/PUB/1365, 375 pp. Date of Issue: 8 April 2009) presents the results of an FAO/IAEA coordinated research project (CRP) on the use of irradiation to ensure the safety and quality of pre-prepared foods. There is an increasing worldwide demand for pre-prepared and take-away meals. However, the traditional methods of preparing convenience foods via retort-processing and freezing are being replaced in favour of chilled foods, due mainly to their fresher and often more appealing appearance. Chilled prepared foods, however, are non-sterile and their heightened potential for microbiological contamination creates a considerable limitation to their shelf-life. The findings of this CRP demonstrate that radiation processing of pre-prepared meals results in a safer product by eliminating existing pathogens, and thereby reducing health risks while extending the foods’ commercial shelf-life.
This publication presents the findings of the CRP and offers a discussion of the possible further utilization and marketing of this new application of irradiation technology (IAEA News)
This publication presents the findings of the CRP and offers a discussion of the possible further utilization and marketing of this new application of irradiation technology (IAEA News)
Monday, November 15, 2010
FDA Unveils Initiative to Reduce Unnecessary Radiation Exposure from Medical Imaging
The U.S. Food and Drug Administration (FDA) today announced an initiative to reduce unnecessary radiation exposure from three types of medical imaging procedures: computed tomography (CT), nuclear medicine studies, and fluoroscopy. These procedures are the greatest contributors to total radiation exposure within the U.S. population and use much higher radiation doses than other radiographic procedures, such as standard X-rays, dental X-rays, and mammography.
These types of imaging exams expose patients to ionizing radiation, a type of radiation that can increase a person’s lifetime cancer risk. Accidental exposure to very high amounts of radiation also can cause injuries, such as skin burns, hair loss and cataracts. Health care decisions made by patients and their physicians should include discussions of the medical need and associated risks for each procedure.
While there is some disagreement over the extent of the cancer risk associated with exposure to radiation from medical imaging, there is broad agreement that steps can and should be taken to reduce unnecessary radiation exposure. For example, the radiation dose associated with a CT abdomen scan is the same as the dose from approximately 400 chest X-rays. In comparison, a dental X-ray calls for approximately one-half the radiation dose of a chest X-ray. Both diagnostics serve important, sometimes critical, public health needs.
Through the FDA’s regulatory oversight of medical imaging devices, such as CT scanners, and through collaboration with other federal agencies and health care professional groups, the FDA is advocating the adoption of two principles of radiation protection: appropriate justification of the radiation procedure and optimization of the radiation dose used during each procedure. The three-pronged initiative the FDA is announcing is expected to promote the safe use of medical imaging devices, support informed clinical decision-making, and increase patient awareness of their own exposure.
The FDA recommends that health care professional organizations continue to develop, in collaboration with the agency, diagnostic radiation reference levels for medical imaging procedures, and increase efforts to develop one or more national registries for radiation doses. Quality assurance practices into the mandatory accreditation and conditions of participation survey processes for imaging facilities and hospitals. In a bid to empower patients and increase awareness, the FDA is collaborating with other organizations to develop and disseminate a patient medical imaging history card. This tool, which will be available on the FDA’s Web site, will allow patients to track their own medical imaging history and share it with their physicians, especially when it may not be included in their medical records (FDA NEWS RELEASE).
These types of imaging exams expose patients to ionizing radiation, a type of radiation that can increase a person’s lifetime cancer risk. Accidental exposure to very high amounts of radiation also can cause injuries, such as skin burns, hair loss and cataracts. Health care decisions made by patients and their physicians should include discussions of the medical need and associated risks for each procedure.
While there is some disagreement over the extent of the cancer risk associated with exposure to radiation from medical imaging, there is broad agreement that steps can and should be taken to reduce unnecessary radiation exposure. For example, the radiation dose associated with a CT abdomen scan is the same as the dose from approximately 400 chest X-rays. In comparison, a dental X-ray calls for approximately one-half the radiation dose of a chest X-ray. Both diagnostics serve important, sometimes critical, public health needs.
Through the FDA’s regulatory oversight of medical imaging devices, such as CT scanners, and through collaboration with other federal agencies and health care professional groups, the FDA is advocating the adoption of two principles of radiation protection: appropriate justification of the radiation procedure and optimization of the radiation dose used during each procedure. The three-pronged initiative the FDA is announcing is expected to promote the safe use of medical imaging devices, support informed clinical decision-making, and increase patient awareness of their own exposure.
The FDA recommends that health care professional organizations continue to develop, in collaboration with the agency, diagnostic radiation reference levels for medical imaging procedures, and increase efforts to develop one or more national registries for radiation doses. Quality assurance practices into the mandatory accreditation and conditions of participation survey processes for imaging facilities and hospitals. In a bid to empower patients and increase awareness, the FDA is collaborating with other organizations to develop and disseminate a patient medical imaging history card. This tool, which will be available on the FDA’s Web site, will allow patients to track their own medical imaging history and share it with their physicians, especially when it may not be included in their medical records (FDA NEWS RELEASE).
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