• Topic ID: id_15460486
  • Version: 4.0
  • Date: Sep 26, 2020 10:11:52 PM

JEDI Noise Test (Pro16, RT)

Prerequisites

Overview

The objective of this procedure is to verify that the DAS is not affected by noise created by the JEDI X-Ray Generator subsystem, in particular the High Voltage cables connecting the inverter to the tank. Procedure summary:

  • Block collimator output so x-rays do not hit detector

  • Take scan

  • Analyze data and compare to specs

Procedure

  1. Set up test scans.
    1. Remove gantry right side cover.
    2. Turn off the axial drive enable switch on the Service Switch Panel.
    3. Remove the mylar scan window.
    4. Rotate the gantry so that the tube is at the 6 o'clock position (tube at the bottom with the window facing up).
    5. Engage rotational lock. Check that the gantry is securely locked by attempting to rotate the gantry by hand.
    6. Fold a lead apron so that it is an inch or more thick. Cover the window of the tube with this lead apron so that x-rays cannot escape the tube.
    7. Launch the DIAGNOSTIC DATA COLLECTION tool.
    8. Select STATIC SCAN - X-RAYS ON. Prescribe a scan with the parameter values described below. Leave everything to default and make the following changes:

      • kV - 120

      • mA - 440

      • Gain - 3

      • Filter - BLOCKED

      • Slice Thickness - 16 X 1.25 MM

      • Cal Vectors - NONE

      note:

      Before pressing the scan enable button, verify gain has not changed by itself to some other value.

  2. Perform the scan.
  3. Select STATIONARY SCAN - X-RAYS OFF. Prescribe a scan with the parameters described below. Leave everything to default and make the following changes:

    • Gain - 3

    • Rotor Rx Overrides - ON

    • Slice Thickness - 16 x 1.25mm

    • Cal Vectors - NONE

    note:

    Verify that gain has not changed by itself to some other value.

  4. Perform the scan.
  5. Analyze the data:
    1. Open the Common Service Desktop and press the IMAGE QUALITY button.
    2. RUN SCAN ANALYSIS tool.
    3. Find the scan you just performed and select Create MSD DD File.
    4. Create an MSD DD file for each scan. Wait for message indicating file(s) created.
    5. Select the DD tab, then select Update
    6. Find the two MSD files you just created
    7. Select the MSD file for scan 1 (the X-Ray on scan) and press the File 1 button. For the X-Ray off scan, select File 2.
    8. Under Math Operations make sure the plot button is selected and press the file subtraction button (-). The second scan will be subtracted from the first and a plot of the difference will be displayed.
    9. Scroll through each of the Vector 2 plots for each set. Compare the values to the specifications table.
  6. Scroll through each of the standard deviation plots. Record the maximum values found in each range of channels in the middle two rows of Table 3.
  7. The test fails if any of the observed maximum values are greater than the spec. A likely cause is the positioning and securing of the high voltage cables between the tank and inverter. See Inverter/Tank AC Wire Routing for more details. This test must pass for the system to be used.

Finalization

No finalization steps.