Radiation monitoring devices

In some cases radiation shields are provided to protect against heat effects from fire incidents and operation requirements. The shields usually are of two styles either a dual layer wire mesh screen or a plexy-giass see through barrier. The shields provide a barrier from the effects of radiant heat for specific levels. They are most often used for protection against flare heat and for barriers at fixed firewater monitor devices, most notably at the helidecks of offshore facilities. 

Radiation monitoring laboratories seeking to achieve optimum proficiency test results with an accreditation standard must use calibration methods that duplicate or at least closely approximate the irradiation protocols described in the accreditation standard. This requirement is particularly important for calibrations using photons with energies below 200 keV where irradiation conditions must recreate the scattered radiation that contributes significantly to the response of the monitoring device. 

The calibration procedure provides a body of data about how the personal monitor responds to the various irradiation conditions. These data are converted into formulas or algorithms that generate a value for Hp(lO) for the irradiation conditions assumed in the workplace. The formulas or algorithms apply to the personal monitor system calibrated, and do not change unless there is a modification in the design or types of radiation detectors used in the personal monitor. An example of such a body of data for a particular monitoring device is provided by Ehrlich and Soodprasert (1994). 

When only one individual monitoring device is used and it is located at the neck outside the protective apron, the reported deep dose equivalent shall be the [//g] for external radiation or 2. When only one individual monitoring device is used and it is located at the neck outside the protective apron, and the reported dose exceeds 25 percent of the limit specified. .., the reported deep dose equivalent value multiplied by 0.3 shall be the [ITe] for external radiation or 3. When individual monitoring devices are worn, both under the protective apron at the waist and outside the protective apron at the neck, the [He] for external radiation shall be assigned the value of the sum of the deep dose equivalent reported for the individual monitoring device located at the waist under the protective apron multiplied by 1.5 and the deep dose equivalent reported for the individual monitoring device located at the neck outside the protective apron multiplied by 0.04. ... 

The amount of time they can safely work in an area contaminated with radioactive materials Equipment needed to protect ihem.seives from radiation and radioactive materials Types of respiratory devices needed to work in the contaminated area How to use radiation monitoring devices... 

Personal Monitoring Devices— Devices worn or carried by an individual to measure chemical exposure and/or radiation doses received. 

Wear appropriate monitoring devices when working near ionizing radiation. 

Ultraviolet and Infrared Radiation Monitoring Devices. A variety of instruments are commonly used to measure ultraviolet and infrared radiation.They are classified according to the type of detector used, which is generally one of two types thermal detectors or photoelectric detectors. Thermal detectors are those in which the absorbed radiation is degraded to heat and subsequently converted to an electric signal by changing the electric resistance of a filament. Photoelectric detectors are based on the principle that the absorbed photons eject electrons from a material. Most of these instruments are precalibrated by the manufacturer, but should be routinely checked prior to field use. 

Microwave Monitoring Devices. Most microwave radiation detectors consist of the following components a test antenna, an attenuator, a bolometer or thermistor, and a power meter. These detectors are usually in the form of a single integrated unit. The test antenna is specific to certain wavelengths and, therefore, interchangeable. These units must be calibrated at frequencies throughout the band to ensnre accnracy. 

Laser Monitoring Devices. A wide variety of laser radiation detectors are commercially available to fulfill the diversified needs resnlting from different wavelengths, pulse durations, and power and energy densities of various laser instruments. Laser radiation detectors are generally based on either of two basic principles—photon or thermal detection. 

In the selection of radiation monitoring devices the following characteristics, at the minimum, should be considered ... 

When working second and third shifts, develop proper sleep and diet patterns Learn to identify hazards associated with various shifts or job assignments Seek assistance from organizational sources to deal with job-related stress Help keep all corridors and other passages clear of clutter and equipment Practice good electrical safety in the performance of aU duties If exposed to radiation, follow established procedures and wear a monitoring device Learn to identify safety hazards including fire prevention... 

A survey is an evaluation of the radiation hazards incident to the production, use, release, disposal, or presence of radioactive materials or other sources of radiation under a specific set of conditions. When appropriate, such evaluation includes a physical survey of the location of materials and equipment, and measurements of levels of radiation or concentrations of radioactive material present. Every employer should supply appropriate personnel monitoring devices such as film badges, pocket chambers, pocket dosimeters, or film rings for use by exposed employees. Personnel monitoring equipment refers to devices designed to be worn or carried by an individual for the purpose of measuring the dose received. 

Control Devices. Control devices have advanced from manual control to sophisticated computet-assisted operation. Radiation pyrometers in conjunction with thermocouples monitor furnace temperatures at several locations (see Temperature measurement). Batch tilting is usually automatically controlled. Combustion air and fuel are metered and controlled for optimum efficiency. For regeneration-type units, furnace reversal also operates on a timed program. Data acquisition and digital display of operating parameters are part of a supervisory control system. The grouping of display information at the control center is typical of modem furnaces. 

Active devices intended to emit ionizing radiation and intended for diagnostic and therapeutic interventional radiology including devices which control or monitor such devices, or which directly influence their performance, are in Class lib. 

The establishment of performance criteria for a given tumor marker test is not a simple process because accuracy and precision are unique for each type of analyte and its application. Establishing methodological limits for accuracy, precision, sensitivity, and specificity often requires standard reference materials, quality control materials, comparative studies, and actual clinical specimens. Accuracy and precision must be measured over the analyte reportable range for which the device is intended to be used. Sensitivity and specificity must be considered with respect to the intended clinical use of the device. Also, the indications for use should be carefully considered in the design of the study protocol. The indications for class II should be to monitor residual tumor after surgery (or radiation), the recurrence of tumor, or response to therapy. A 510(k) must provide clear evidence that the device is accurate, safe, effective, and substantially equivalent to a device legally marketed in the United States. 

The function of the detector in hplc is to monitor the mobile phase emerging from the column. The output of the detector is an electrical signal that is proportional to some property of the mobile phase and/or the solutes. Refractive index, for example, is a property of both the solutes and the mobile phase. A detector that measures such a property is called a bulk property detector. Alternatively, if the property is possessed essentially by the solute, such as absorption of uv/visible radiation or electrochemical activity, the detector is called a solute property detector. Quite a large number of devices, some of them rather complicated and tempremental, have been used as hplc detectors, but only a few have become generally useful, and we will examine five such types. Before doing this, it is helpful to have an idea of the sort of characteristics that are required of a detector. 

Any device that can monitor radiation can be used as detector. In most cases, end-on and side-on photomultiplier tubes (PMT) are used. The end-on PMT has the benefit of circular photocathode, which views more effectively the radiation emitted from the circular flow cells. Nonetheless, the side-on PMTs are more commonly used due to their lower cost. The signal from the PMT is current and, hence, in most applications a current-to-voltage converter is required to convert the current to voltage, which is then monitored. 

---