All medical x-ray procedures have a small risk associated with it. We need not accept this risk if it is not essential. In this debate, the word ‘necessary’ should be given proper emphasis. “The final responsibility for wasted x rays lies in the finger on the switch and the willingness of a few people to sometimes refuse to push the button. It should be possible to decide with accuracy, when x rays should be used and to eliminate senseless repetition and interminable follow up examinations” In 1970, the Radiology journal reprinted as editorial, an article entitled “Wasted X rays” by John L. McClenahan, an eminent radiologist.
This editorial is relevant now as the US Department of Health and Human Services,(USDHHS) in its 11th Edition of the Report on Carcinogens (ROC), released on31 January 2005, added x-rays and gamma rays to the list of “known human carcinogens”. The need to exercise greater caution in the use of x rays and gamma rays in medical procedures is obvious.
The International Agency for Research on Cancer (IARC) found sufficient evidence of carcinogenicity in humans exposed to x rays and gamma radiation. The National Toxicology Program (NTP) of US-DHHS relied on these findings to prepare the report.
IARC found strong association between radiation and cancer consistently in many different populations exposed at different times and in different countries throughout the world. The risk increased with dose.
Radiologists, medical physicists and other professionals expected the report from NTP. The Radiological Society of North America, the professional association of radiologists in USAreacted with predictable alacrity; within two hours of the report’s release, the Society issued a press release clarifying the benefits of medical x-ray procedures.
Medical X- ray equipment is a uniquely beneficial diagnostic tool. When well trained professionals carry out clinically indicated procedures, using optimally adjusted equipment, benefits from x-ray examinations far outweigh the risks.
What is the status of radiation safety in medical x-ray installations inIndia? A nation wide survey organized by the Atomic Energy Regulatory Board revealed that about 30 % of about 30,600 units, enumerated by AERB, are over 15 years old. Such units require detailed safety evaluation.
The lay out of many x-ray rooms was improper as they did not consider safety aspects. In 60 % of installations the area of the rooms was less than specified. Seventy percent of the installations did not have red light indicators to prevent entry of persons when the machine was being used.
The wall thickness of x-ray rooms was inadequate in many installations. Use of plywood which offers no protection was common. In several instances, the x-ray beam is inadvertently directed towards waiting areas of the patients or other occupied areas in the vicinity exposing unsuspecting people to x rays unnecessarily. Crowding in X ray room is a common practice.
Even in facilities which had protective accessories such as lead apron, the workers did not have the motivation to use them, as they were inadequately trained. Obviously, we can achieve significant improvement in protection by enforcing simple measures at little cost.
Researchers supported by AERB, measured radiation doses in 12 different x-ray examinations. For the same type of examinations, x-ray doses varied widely. For instance, the ratio of the maximum to minimum dose in chest x-ray examinations was 5; lumbar spine 8; thoracic spine 8.5. It means that in a chest x-ray examination, you may get a minimum dose or five times the dose during a successful diagnosis depending on the equipment. . How can any one justify such a practice?
The doses were mostly within the guidance levels recommended by the International Basic Standards for the Protection of Radiation Sources and the Safety of Radioactive Materials jointly sponsored by agencies such as the IAEA,WHO, ILO etc
But that is not enough. There is scope to reduce x-ray doses considerably without losing clinical benefits . In view of the possibility of harmful effects, medical x-ray procedures should be carried out by exposing the patients to doses As Low As Reasonably Achievable (ALARA).
Specialists must adjust the equipment optimally to comply with the ALARA principle. Manufacturers must get their units type approved by AERB. Such units satisfies built-in safety requirements. AERB has so far type approved over 850 combinations of x-ray generator, tube and couch produced by major manufacturers.
It is illegal to install and use a non-type approved x-ray equipment. The buyer must insist that the unit satisfies the safety requirements specified in the “AERB Safety Code on Medical Diagnostic Equipment and Installation” (It can be “downloaded” from www. aerb.gov.in, the web site of AERB).
About 1200 X-ray units are added nationwide annually to the existing 46,000 x-ray units. Both old and new units must undergo quality assurance tests periodically. Specialists must examine every unit initially to ensure that they work safely. They must weed out old and unsafe equipment. Since the units are distributed across the country monitoring and maintaining the status of radiation safety in every x-ray installation is a daunting task.
Monitoring and maintenance of the status of radiation safety of each medical x-ray installation can be more effectively ensured only if the work is decentralized. Each State must set up a small independent agency to ensure that the x-ray units satisfy the mandatory requirements of AERB. The State Governments must play a proactive role in this as they own a major fraction of the medical x-ray installations and employ radiation workers in these installations.
In 1996, the Government of Kerala set up the Directorate of Radiation Safety (DRS), as an independent agency, reporting directly to the Secretary, Department of Health and Family Welfare to enforce the provisions in the AERB Code on medical diagnostic x-ray equipment and installations in Kerala.
The Government of Kerala Terms and Conditions of Supply 2005 stated that approval of electrical connection to Radiation Generating Plants like X-ray/CT units/Fluoro Image Intensifier/ Mammography/ etc. shall be provided only after getting clearance from Directorate of Radiation Safety. The rules also included conditions to disconnect or connect power supply on receiving intimation that the installation violated Radiation Protection Rules. These provisions are unique as they exist only in Kerala.
In spite of dedicated efforts by the Atomic Energy Regulatory Board, there is no significant progress in setting up Directorates by other States. AERB must start acting against the x-ray installations violating the rules. This will provide the much needed incentive to the States to set up DRS to enforce radiation safety provisions in the x-ray installations owned and operated by the State Government.