Isotopes, Figure 01, (The units are Bq)

Isotopes, Figure 01, (The units are nCi)

This part of the program allows you to select the radionuclides which will be routinely included in the analysis. The selection of the nuclide is done by simply clicking on the checkbox at the left of the name of the nuclide, as seen in Figure01, above. (Note that the list is sorted alphabetically." The choice of which nuclides to check should be made by the Site Health Physicist; his choices should be based on the history of the work being performed at the site.

Potassium-40 should always be checked because this is a natural constituent of the human body. A Compton scatter factor should always be chosen because in any type of shadow shield radiation counter, there will always be scattered radiation from cosmic rays and the ambient environmental radioactive components. Where installations where most of the work involves mixed activation, fission, and corrosion products, the typical nuclides should be added, such as cobalt-60, cesium-137, i.e., nuclides with a fairly long half-life. If there is historical information on the materials currently being used at the site that might contain shorter half-lives, these nuclides should be added to the list, also, such as manganese-54, cobalt-58, cesium134, etc.

The nuclides chosen in Figure-01 are:

1. ATGCOMPT (a Compton scatter calibration file)
2. BA133DT (a barium-133 calibration file based on the source being in the thyroid of the do-it-yourself counter)
3. CO60DXL (a cobalt-60 calibration based on the source being in the lung of the do-it-yourself counter)
4. CS137DW (a set of cesium-137 sources distributed uniformly throughout the phantom, note the "W" for whole body)
5. K40DXWB (a set of natural potassium sources distributed uniformly throughout the phantom, note the "WB" for whole body

The "Least Squares" program tries to fit the data from the subject with the data in the calibration files. If a radionuclide is present in the body of a person but is missing from this "library" or list, then you probably will see the photopeak of the missing radionulide in the "Sigma" graph discussed briefly in the chapter on "Data Analysis." Search for the words "Sigma Graph." It is an easy task to add a radionuclide to the list, then re-analyze the person's data.

This option allows the operator to select the library extension whih will be used for all analyses. Let us assume, for example, that there are two "Do-It-Yourself" counters, "A" and "B." All of the calibration data for "DIYS A" have extensions of ".DYA" while the calibration data for "DIYS B" have extensions of ".DYB." Both "DIYS" counters have their own individual calibration data, all told, typically, the data are almost identical because the instruments are built to the same physical specifications. If both sets of data are written to the same floppy disk, one set will not overwrite the other because they have different extensions.

1. The Annual Limit of Take (ALI) as defined by the appropriate regulatory authority or a recognized international source of this information, such as the ICRP,
2. The action point as chosen by the Site Health Physicist,
3. The start of the region of interest, expression a channel number, and
4. The end of the region of interest, expressed in the channel number.

These four pieces of information are actually found at the bottom of the calibration data file. There are actually six pieces of information there, the four mentioned above, plus whether or not the information for that nuclide should be printed on the final report (This is either a "Y" or a "N"), and the name that is printed on the report.

		
		

			

				

					
					Start channel ROI..........: 219

					End channel ROI...........: 245

					%ALI...........................: 1.000000000000E+0006

					Print results ?................: Y

					Action point..................:  1.000000000000E+0002

					Nuclide name.................: COBALT-60