The assumption must also be made that you have setup the list of nuclides (isotopes) for which analyses are to be made. If this step has not been taken, please go back to the Main Menu And Click First on "Parameters" and choose "Isotopes" from the various parameter options, or click on the following link:

This next screen shows the result of clicking a second time on the "Name" column. Now the names are listed in the reverse alphabetical order.

Figure Auto-Analysis-06

Now that we have reviewed the various options for sourcing the names in our list of files to be analyzed, let us revert back to the original screen for the names are in time sequence. So that you do not have to go up the page, that first figure is repeated here and given a new filename.

Figure Auto-Analysis-07

We are now ready to select a file for analysis. It would seem logical to choose the very first person on the list, however, this particular set of data contains files that were collected without obtaining a new background. This doesn't mean that we can't analyze these files, however, this is not the appropriate place to discuss the resulting analysis of such a file, that discussion will come later.

Therefore, we will select the name of Mr. Curt Cannon, not because he is the CEO of this corporation, but because he has a good set of data that contain no problems.

Now let us pay attention to the boxes at the bottom of the screen. Note that only two boxes are highlighted, "Select All Files," and "Close." If you wish to analyze only a few files, then find the name of the individual and just click the box to the left of the persons name and analyze, one at a time .

Therefore, the next screen capture shows that we have put a checkmark in the box to the left of the name of Mr. Cannon.

Figure Auto-Analysis-08

Now all boxes are highlighted with the exception of the "Netplot" box. (The "Netplot" software will not be discussed in this document at this point in time.) These boxes are self-explanatory. Since we have checked only one individual, we will analyze the data from that person using the "Auto Analyze" option. Just click on the "Auto Analyze" box. (The subject of "Manual Analysis" is discussed in a separate chapter entitled "Manual Analysis.")

In 5 to 15 seconds (depending on the speed of your processor and a number of other tasks which are being simultaneously performed), the screen will show the results of this analysis, as shown in the screen capture, below. Note that we see the subject gross counts per second, the red line, the background counts per second, the dark blue line, and the net counts per second, the black line. Additionally, we see the Compton spectrum, a light blue line that looks as if it has the characteristics of a straight line on a semi-log graph, and we see the potassium-40 spectrum, also a light blue line. The background spectrum as well as the Compton and potassium-40 spectra are shown in proportion to the amounts that the software found. This will be discussed further several paragraphs down under the heading "Results Values."The writer of this document, Lew Helgeson, prefers this type of presentation because it gives an opportunity to see how well the software analyzed the data. (Other options are possible where not so much information is shown. These options are chosen in the "Graph Parameters" section of this document.)

Figure Auto-Analysis-09

You will note that there are really three parts to this screen, the main graphic display area, and options area at the bottom of the screen, and an area on the right side of the screen that contains vital information pertaining to the quality of the analysis. We need to discuss each of these areas. The main graphic display area has already been discussed just above the previous screen capture.

Therefore, let us start by discussing the various options shown by the highlighted boxes at the bottom of the previous figure.

Graph Spectrum

Figure Auto-Analysis-10

The screen capture above shows the subject, that ground, and net spectra from this analysis. Note that the individual components spectra are not displayed. This is a choice we made in writing the software so that you may see the data without any confusion from the individual components spectra. If you only want this type of display, then make the change in the "Graph Parameters" portion of this instruction manual.

Results Values

Figure Auto-Analysis-11

analysis results The screen capture above shows the results of the analysis. (We are making a modification to the software so that these results may be put in a specific order, defined by the user under the "Parameters" heading.) The units in which the results are expressed, whether in units of "NanoCuries" or units of "Becquerels" are also defined by the user under the "Parameters" heading.

QC Data

Figure Auto-Analysis-12

The screen capture above shows a quality control data that were obtained for this particular count. A description of all of the quality control data points is given in Chapter 21 of the DOS version of the "HELGE" System Managers Reference Manual. This chapter is not on the web but can be sent to you (if you do not already have it) in hard copy format.

Personal Details

Figure Auto-Analysis-13

This page contains obvious information that needs no discussion.

Cal Data Graph

Figure Auto-Analysis-14

The reader will notice that this is exactly the same screen that was shown at the completion of the analysis.

Sigma Graph

Figure Auto-Analysis-15

This screen capture shows the differences between the measured values and the calculated values expressed in units of Sigma. Normally, the Y-axis scale is from -5 sigma to +5 sigma. This first graph shows a much wider y-axis scale, most likely due to the use of a "Compton Scatter" calibration data file man should be used for this particular location. This potential problem is being investigated.

The "Sigma" graph shows the residuals expressed in units of sigma. This is probably the most important graph of the least squares series since it shows the quality of fit of the least squares calculations to the original data. The data points which have been graphed represent the differences between the original data and the calculated results, expressed in units of sigma. The value of this graph lies in the fact that if a nuclide is present in a person but is not included in the library of calibration nuclides used for the analysis, the photopeak spectrum of that unidentified nuclide appears as a photopeak above the 0 line which is opposite the word sigma and represents Zero sigma. If a nuclide is present but, for some reason, the program calculates that more activity is present than there actually is, then there would be an inverted photopeak going in a negative direction. This shows that the amount was over-estimated. Depending on the magnitude of the over-estimate, perhaps it should be investigated.

Figure Auto-Analysis-16

The Y-axis of the Sigma graph may be changed by right clicking on the Y-axis and choosing a new set of maximum and minimum values.

Figure Auto-Analysis-17

In this particular wrote there is a slight variation at approximately channel 284. Note that the Y-axis dips down to about -2.5 sigma and then rebounds upwards to slightly more than 1-sigma. This suggests that the gain shift routine was off probably a fraction of a channel. If the active roles under the negative and positive "photopeaks" were added together, there would be a net effect of essentially zero. This means that the potassium analysis is completely acceptable.

To show the effects of a missing nuclide in the "Isotope" selections listing, we have deliberately taken the potassium out of the group, as shown in the screen capture below.

Figure Auto-Analysis-18

Let us analyze the original file without the potassium.

Figure Auto-Analysis-19

We see that the black curve, representing the net counts per second shows the potassium peak was present, but that when looking for the "Individual Components," potassium is not listed. Now let's look at the Sigma graph.

Figure Auto-Analysis-20

The potassium-40 photopeak is very evident, strongly indicating that a nuclide is missing from the choice of the isotopes for the analysis. This is a very simple and positive clue for the technician performing these analyses to find out why there is such a strong positive photopeak.

Profile Data

Figure Auto-Analysis-20

The Profile Data is another important graph provided by the "HELGE" software because it allows the health physicist to see an approximate distribution of radioactivity in the subject. There are 120 channels of profile data and the time interval spent on each profile data point is determined by dividing 120 by the number of seconds of the length of the count. Thus, if the typical subject counting time is eight minutes, then the time for each data point is equal to 960/120 = 8 seconds. This represents the total number of counts obtained in that time interval over the energy range of approximately 100 KeV to about 2.4 MeV. In an individual who were there is no measurable in trouble deposition of radioactivity, the profile seen in the graph above is very typical because the detector is seeing more natural potassium in the body of the subject as the central part of the body comes beneath the detector. Should there have been a measurable deposition in or on the body, the county rate as a function of location would definitely show elevation in the region of concern.

The screen capture below shows the profile of an internal deposition of cobalt 60 in the lung. The location of the deposition is obvious.

Figure Auto-Analysis-21

This is the end of the discussion of "Auto Analysis."