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Protective Apron Inspection
Posted on Tuesday, June 11th, 2013, under Radiation Safety
By Greg Sackett, M.S., CHP
The inspection of radiation protective aprons is a mysterious requirement without much guidance. Many hospitals and clinics have heard something about inspecting aprons, but many have questions as to what they need to do.
The primary requirement for protective apron inspection is given by the Joint Commission. Some States also require inspection of protective aprons but Missouri, Kansas and Iowa do not have any such requirements. This means that technically only those institutions accredited by the Joint Commission are required to inspect their protective aprons annually.
The Joint Commission requirement may be satisfied by physical inspection OR fluoroscopic examination of protective aprons annually. While fluoroscopic examination is believed to be more thorough, it may not be necessary for newer aprons and may deliver unnecessary exposure to the persons testing the aprons. Fluoroscopic testing may be considered for aprons considered suspect following physical examination. If fluoroscopic testing is performed, low technique factors and not automatic exposure control should be used to reduce operator exposure.
The keys to a successful apron inspection program are as follows:
- Uniquely identify each item of protective equipment with a number and some method of determining when it was last inspected. This may be done on the label/tag itself or with a database that tracks all of the items and when they were inspected. If a database is used, results must be available for inspection by the Joint Commission.
- Develop a procedure for inspecting the protective equipment, either physically or fluoroscopically (or both).
- Develop criteria for determining when protective equipment is defective. Such criteria may include:
- Tears, perforations, or seam separation.
- Holes larger than 15 mm2 unless it is not positioned over a critical organ.
- Velcro that is no longer functioning.
- Aprons determined to be defective should be removed from service immediately and disposed of properly (as hazardous material/waste if they contain actual lead).
Establishment of a protective apron inspection program may not be required at your facility but should be considered in order to give assurance to staff that the protective equipment they have available is not defective.
References:
- “Inspection of lead aprons: Criteria for rejection,” Operational Radiation Safety Volume 80, May 2001
- “Implementation of an X-ray Radiation Protective Equipment – Inspection Program” published in Operational Radiation Safety Vol 82, Feb. 2002, pp 551-553
What Can We Say About Patient Dose in CT Exams?
Posted on Tuesday, April 2nd, 2013, under CT
By Stephen E. Hale Jr., Ph.D.
Radiation dose from Computed Tomography (CT) exams has recently become a hot topic among the medical community, the legal community, and the public in general. Overdoses from brain perfusion studies at several medical facilities in California and Alabama have contributed to this rise in concern. But what can a CT technologist or radiologist actually tell their patients about the amount of radiation administered during a CT exam?
Each CT machine will typically provide both an estimated CTDIvol and DLP value before an exam is conducted. CTDIvol stands for volume Computed Tomography Dose Index, while DLP stands for Dose-Length Product. Neither of these is actually a measure of the dose a patient will get from the exam. They are actually designed as metrics for comparing one protocol to another, one machine to another, or even one facility to another, in terms of the amount of radiation produced by the system. As such, they can be used to guide adjustments to the techniques of a given protocol, such as kVp, mA, rotation time, mAs, or even pitch for helical scans.
Dose is defined as the amount of energy absorbed from radiation passing through material divided by the amount of mass that is actually absorbing the energy. The more energy absorbed in the same amount of matter, such as a patient’s body, the more dose is absorbed, and therefore the greater potential for damage. Similarly, the same amount of energy absorbed in a smaller body will also result in a greater potential for damage.
The CT machine has no knowledge about the patient who will be scanned nor what portion of the patient’s anatomy will be examined. If a large patient is scanned with the same techniques as a small patient, the smaller patient will have less mass exposed to the same amount of radiation, and thus experience a higher dose. Different portions of our bodies are more sensitive to radiation than others. Thus having a CT exam with a set of technique factors over a patient’s feet will have much less detriment to the patient than the same exam over a patient’s head.
A good analogy to this situation is that of a tachometer in a car relative to the car’s speed. The tachometer displays how many revolutions per minute the engine is spinning the crankshaft, but it has no knowledge about the gear selected by the transmission or the size of the wheels and tires on the car. For a given RPM, a higher gear means a faster speed. Similarly, if the wheels and tires are replaced with a larger set, a given RPM of the engine and the same gear will result in a faster speed. The CTDIvol and DLP values are the equivalent of the tachometer, reporting how the CT machine is performing. But without information about the patient undergoing the procedure, nothing can be said about the dose absorbed.
Without knowledge of the patient’s size or the anatomy being scanned by the CT, it is not possible to tell the patient how their radiation dose compares to other sources or exams. With images of the patients and information about the parameters of the exam on the CT system, physicists can calculate actual radiation doses to patients. This is one of the many services provided by Integrated Science Support, Inc.
References:
- “Two more hospitals report CT scan radiation overdoses” LA Times, Online 8/3/2010