The subject invention relates to x-ray devices

X-Ray Fluorescence Analysis (XRF) is a nondestructive physical method used for chemical elemental analysis of materials in the solid or liquid state. The specimen is irradiated by photons or charged particles of sufficient energy to cause its elements to emit (fluoresce) their characteristic x-ray line spectra.The detection system allows determining energies of the emission lines and their intensities. Elements in a specimen are identified by their spectral line energies or wavelengths for qualitative analysis, and intensities are related to concentrations of elements providing opportunity for quantitative analysis. Computers are widely used in this field, both for automated data collection and for reducing the x-ray data to weight-percent and atomic-percent chemical composition or area-related mass. Email:marketing@medicilon.com.cn web:www.medicilon.com

Abstract:An XRF analysis apparatus includes a housing with a source of penetrating radiation to be directed at a sample and a detector for detecting fluoresced radiation from the sample. A shield is attachable to the housing to protect the user from radiation and a safety interlock is configured to detect whether or not the shield is attached to the housing. A controller is responsive to the safety interlock, and configured to monitor usage of the source of radiation at or above a predetermined power level when the shield is not attached to the housing and provide an output signal when the monitored usage of the source of penetrating radiation at or above the predetermined power level without the shield attached to the housing exceeds one or more predetermined thresholds.

The shields for these devices, typically attached to the nose of the instrument, serve to protect the user of the device from radiation. Radiation limits are usually established by regulations which may vary by jurisdiction.

For handheld XRF devices with lower power x-ray tubes, reaching a radiation limit is not as big a concern as with higher power x-ray tubes used in some industries. This is because at tube voltages of 50 kV and higher, a greater amount of x-ray radiation between 40 kV and 50 kV is produced. These energies are harder to shield while still maintaining the small size and minimal weight needed for a handheld device. Thus there are more x-rays emitted from the device, than in lower voltage portable XRF devices. In addition, the 40 kV-50 kV x-rays are more likely to scatter multiple times within a sample, rather than be absorbed by the sample, and then be directed back towards the operator. Also, in some instruments, the power output by the x-ray tube can be varied.

BRIEF SUMMARY OF THE INVENTION

Some portable XRF devices have been introduced with an external shield over the end of the unit, where the x-rays are emitted. While this shielding does reduce radiation levels external to the device, compared to with the external shield removed, using an external shield has a number of disadvantages. Shielding can be misplaced or may be removed from the instrument by the user. Some shield designs can also be bulky and interfere with normal usage of the instrument especially when testing smaller samples. It may be hard to position the portable XRF device so that the desired area of a sample is being irradiated. Shields also generally add weight to the XRF instrument, and negatively impact the ergonomics, making them “end heavy” and unbalanced since the externally added shields are often at the end of the pistol-shaped XRF device.

If a user operates a higher power XRF instrument without the shield installed, the user often does not know if he has been exposed to the maximum allowed amount of radiation nor does he know his current usage time or how his current usage time relates to the maximum amount of radiation allowed. Typically, the maximum allowed amount of radiation is indicated in regulations maintained by an allowed body in the region where the XRF instrument is used.

Featured is an XRF analysis apparatus comprising a housing with a source of penetrating radiation to be directed at a sample and a detector for detecting fluoresced radiation from the sample. A shield is attachable to the housing to protect the user from radiation. A safety interlock is configured to detect when the shield is attached to the housing. A controller is responsive to the safety interlock and configured to monitor usage of the source of radiation at or above a predetermined power level when the shield is not attached to the housing and to also provide an output signal when the monitored usage of the source of penetrating radiation at or above the predetermined power level without the shield attached to the housing exceeds one or more predetermined thresholds.

In one example, a predetermined threshold is a first percentage of a maximum allowable allowed dose. When the monitored usage of the source exceeds this first percentage of the maximum allowable allowed dose, the output signal provided includes a first notification or message to the user noting the monitored usage and the percentage of the maximum allowable allowed dosage. Another predetermined threshold can be a second percentage of the maximum allowable allowed dose. When the monitored usage of the source exceeds that percentage, the output signal provided is designed to provide a second notification to the user. Still another predetermined threshold can be a third percentage of a maximum allowable allowed dose and when the monitored usage of the source exceeds that percentage of the maximum allowable allowed dose, the output signal provided is configured to prevent the operation of the source at or above the predetermined power level until the shielding is attached to the housing. Another predetermined threshold might be a fourth percentage of the maximum allowable allowed dose and when the maximum usage of the source equals or exceeds that percentage of the maximum allowable allowed dose, the output signal can be configured to prevent the operation of the source at any power level even if the shield is attached.

The safety interlock may include a circuit associated with the shield providing a signal to the controller when the shield is attached to the housing. In one version, there are contacts on the shield in communication with the circuit and the housing includes contacts for communicating the signal.

An x-ray analysis method in accordance with the invention includes detecting when an x-ray device includes a shield attached thereto, determining if the x-ray device is being operated at or above a predetermined power level without the shield attached, monitoring usage of the device at or above the predetermined power level when the shielding is not attached, and taking one or more actions when the monitored usage of the device without the shield attached exceeds one or more predetermined thresholds.

One preferred version of the invention, in some aspects, relates to a safety interlock configured to detect when the shield is attached to a handheld XRF instrument and, when it is not, the usage time is monitored and action is taken when the usage time meets or exceeds a predetermined percentage of the maximum allowed radiation exposure. The level of the allowed exposure, and warnings when an operator may have reached certain levels of exposure limits can be set at the factory of by a supervisor based on specific allowed limits or company policies. Access to change this setting is preferably password protected.

The subject invention, however, in other embodiments, need not achieve all these objectives and the claims hereof should not be limited to structures or methods capable of achieving these objectives.