g-jaszczak phantom data

Acquiring & Processing Jaszczak Phantom Data Overview

Appendix G Acquiring & Processing Jaszczak Phantom Data Direction 5195795-100, Rev. 1, Copyright 2006 by GE Healthcare G1Infinia + Hawkeye 4 Users Guide

Overview

This section provides a step-by-step description of the steps required for acquiring Tomo images of the Jaszczak Phantom. The following two procedures are described:

Jaszczak Phantom acquisition and processing for ACR accreditation of Infinia cameras

The terms of acquiring and processing are defined in relevant ACR documentation, which is delivered with the accreditation programs. This document is complementary to ACR accreditation instructions and focuses on optimizing the acquisition and reconstruction parameters specific to the Infinia systems.

Jaszczak Phantom acquisition for a general test of the systems Tomo capabilities

Acquisition and processing parameters are supplied with the aim of achieving optimal Tomo images.

Note The Jaszczak "Deluxe" phantom is the ACR approved phantom for evaluating Tomo images quality. If only a Jaszczak "Standard" phantom is available, it may be used instead.

Overview Acquiring & Processing Jaszczak Phantom DataPhantom Description

Phantom Description

Both the Deluxe and the Standard phantoms are Acrylic cylinders with protruding flanged tops and a wall thickness of 3.2 mm. The internal diameter of the cylinders is 21.6 cm and the internal height is 18.6 cm. (see Figure G-1 and Figure G-2).G2 Direction 5195795-100, Rev. 1, Copyright 2006 by GE HealthcareInfinia + Hawkeye 4 Users Guide

Figure G-1 Components of Deluxe Jaszczak Phantom

Figure G-2 ACR Approved Phantom Assembly

Acquiring & Processing Jaszczak Phantom Data System Preparation

The phantoms include six sets of cold rods, and six cold spheres of different diameters, as shown in Figure G-3.Direction 5195795-100, Rev. 1, Copyright 2006 by GE Healthcare G3Infinia + Hawkeye 4 Users Guide

The rods and spheres diameters are specified in Table G-1.

System Preparation

Before acquiring the images, verify that the system is in an optimal state. In particular, verify the following:

z A high statistics uniformity map acquired for both detectors with the relevant collimators (according to the radio-isotope used). The statistics suggested for the maps is at least 120 Mcts per Head (256x 256 matrix).

z Perform the C.O.R. calibration procedure for the relevant collimators. Record the calibration data for further reporting.

z Perform a Uniformity test. Verify that all the uniformity parameters are within tolerance range. Record test results for further reporting.

Figure G-3 Phantom Inserts

Table G-1 Phantoms Insert Dimensions

Phantom Type Rod/Sphere mm mm mm mm mm mmACR approved (Jaszczak Deluxe)

Rods diameter 4.8 6.4 7.9 9.5 11.1 12.7Spheres diameter 9.5 12.7 15.9 19.1 25.4 31.8

Jaszczak Standard Phantom

Rods diameter 6.4 7.9 9.5 11.1 12.7 15.1Spheres diameter 12.7 15.9 19.1 25.4 31.8 38.1

Phantom Adjustment Acquiring & Processing Jaszczak Phantom Data

For more information regarding the procedures described above, contact your local GE representative.

Phantom AdjustmentG4 Direction 5195795-100, Rev. 1, Copyright 2006 by GE HealthcareInfinia + Hawkeye 4 Users Guide

1. Fill the Jaszczak phantom with distilled water, leaving a volume of about 10 ml of air.

2. With the table retracted to maximum OUT position, place the phantom on its side (along the primary patient axis) on a holder protruding from the edge of the table. Pay attention to the following guidelines:

z Position the phantom so that the largest "cold" sphere is placed at the bottom of the phantom, closest to the pallet.

z Phantom should be parallel to the axis-of-rotation in both dimensions (side-to-side and horizontally).

z The phantoms flange should be perpendicular to the gantry axis of rotation.

z The cylinder axis should be close to the gantry axis-of-rotation so that the distance from the face of the collimators to the phantom does not change during rotation. This adjustment is best performed by setting the Gantry to 90 in H-mode and position the detectors close to the phantom (RADIAL IN). Make sure that the sides of the phantom are parallel to the collimators. A ruler may be used to measure the distance between the phantom and the detectors to improve the accuracy of phantoms positioning.

z The phantom should be located between the detectors so that its entire body will be screened. Use the black lines delineating the detectors Field Of View on the collimators face as a reference.

Figure G-4 Jaszczak Phantom Position on the Pallet

Patient TableAvailable ToolingJaszczak Phantom

Acquiring & Processing Jaszczak Phantom Data Gantry Setup

Gantry Setup

1. Set the radius of rotation as follows:

z For ACR accreditation: set the radius of rotation to 20 cm for both detectorsDirection 5195795-100, Rev. 1, Copyright 2006 by GE Healthcare G5Infinia + Hawkeye 4 Users Guide

z For optimal images: set the radius of rotation as close as possible.

2. Measure the distance between Detector 1 and the phantom at two rotation angles: 0 and 180. The two distances should be equal. If not, correct the phantom positioning (modifying table height may be required). After Detector 1 is properly positioned, adjust the position of Detector 2.

3. Carefully rotate the detectors to make sure that no collision occurs between the phantom or stretcher. In case of collision, attempt to slightly move the phantom (left or right) or to move the pallet (up or down) in order to position the phantom symmetrically between the detectors.

If necessary, enlarge the radiuses by a few millimeters (while keeping them equal to each other). Repeat the operation several times until optimal positioning of the phantom/stretcher and the detectors is achieved.

4. When all adjustments are complete, position the gantry at a 90 rotation angle and carefully remove the phantom, so that it will be possible to reposition the phantom in the exact same position.

Jaszczak Phantom Preparation Acquiring & Processing Jaszczak Phantom DataSPECT Acquisition Using Tc99m With LEHR collimators

Jaszczak Phantom Preparation

SPECT Acquisition Using Tc99m With LEHR Collimators

To calculate the activity needed, bear in mind that due to the phantom mG6 Direction 5195795-100, Rev. 1, Copyright 2006 by GE HealthcareInfinia + Hawkeye 4 Users Guide

absorption, the output is about 40% of the inserted Tc99 activity. Count rate should not exceed 30 kc/s.

1. Inject into the phantom Tc99m with an activity (A) of approximately:

Where S is the sensitivity of the Collimator in cpm/Ci.

The best technique is to measure the activity with a Dosimeter. If this is not available, then:

a. Fill the syringe with an amount of Tc99m that will yield a rate of ~30 kc/s in both detectors.

b. Inject 2.5 times this amount of Tc99m into the phantom.

The activity for the LEHR Collimator should be 10-20 mCi.

When injecting liquid into the phantom, a few millimeters of air should be left in the phantom.

2. After injecting the isotope into the phantom, close the phantom and mix the liquid inside as follows:

a. Hold the phantom with the filling cover facing up.

b. Turn the phantom over so that cover is at the bottom and wait for the bubbles to rise.

c. Turn the phantom back to its original position and wait again for the bubbles to rise.

d. Repeat the process for about one minute.

3. Place the phantom carefully in its position towards the gantry. Rotate the gantry a full rotation, ensuring that the collimators do not come in contact with the phantom.

A =15kc/s

S*1/60 (kc/s)/mCi *10.4 =

2250S

[mCi]

Acquiring & Processing Jaszczak Phantom Data Tomo Image Acquisition SPECT Acquisition Using Other Radioisotopes and Collimators

SPECT Acquisition Using Other Radioisotopes and Collimators

Since the ACR applicant may also be requested to submit either Tl201 or Ga67 images (in addition to Tc99m), it is recommended first to fill the phantom with Tc99m solution, perform the images requested, remove the solution, clean the phantom, leave the residual Tc-99m to decay about 12 hours and then to fill the Direction 5195795-100, Rev. 1, Copyright 2006 by GE Healthcare G7Infinia + Hawkeye 4 Users Guide

phantom with Tl-201 or Ga-67 solution.

Recommended amounts of the sources activity are represented in Table G-2.

Tomo Image Acquisition

1. Open the To Do List.

2. Select the [New Study...] button to schedule a new Tomo study.

3. Fill in test details.

4. Press [Select Study Protocol...]. From the Factory\Basic folder, select Tomo.

5. Calculate the required time per view using the average count rate displayed during persistence mode, after pressing [Apply], according to the following:

z For ACR accreditation: time per projection [sec] = 200/average count rate.

z For Optimal images: time per projection [sec] = at least 1000/average count rate.

Table G-2 Recommended Sources Activities

Activity, mCi

Collimator Tc99m Tl201 Ga67

LEGP 7 - 10 5 8

LEHR 10- 20 12 - 15

MEGP 8 - 12

Tomo Image Acquisition Acquiring & Processing Jaszczak Phantom Data

6. In the Tomo Key Parameters panel, select/verify the following parameters:

Table G-3: Tomo Key Parameters

Rotation (total angular range) 360 (180 per detector)

View angle 3 (view #: 120)

Stop on time per projection See Step 5 aboveG8 Direction 5195795-100, Rev. 1, Copyright 2006 by GE HealthcareInfinia + Hawkeye 4 Users Guide

7. Click [Correction Parameters] to go to the Corrections Panel. Verify the following:

8. Start Acquisition using the RCU key.

Zoom 1.33

Y offset Update if required, to get the phantom in the center of the frame

Matrix 128 x 128

Table G-4: Tomo Correction Parameters

Use corrections: Body Contour Off and COR On

Isotope: Tc99m

Collimator LEHR

Acquiring & Processing Jaszczak Phantom Data SPECT Reconstruction

SPECT Reconstruction

The procedure below describes the necessary steps for data reconstruction on Xeleris 2.x workstations. The figures below illustrate a step-by-step procedure of reconstructing and processing of SPECT images of a Jaszczak phantom.Direction 5195795-100, Rev. 1, Copyright 2006 by GE Healthcare G9Infinia + Hawkeye 4 Users Guide

1. Select the Jaszczak Planar projection from the Xeleris Data Management panel.

2. From the applications list, launch the General SPECT application.

3. When reconstruction is completed and the resulting images are displayed (see Figure G-5), select [SPECT Options] from the menu in the left side of the screen.

Figure G-5 General SPECT Reconstruction Images

SPECT Reconstruction Acquiring & Processing Jaszczak Phantom Data

4. From the opened Filtering and Attenuation parameters (see Figure G-6) select the following parameters:.

Area Parameter Name Recommended Parameter

For ACR accreditation: Hann, Critical frequency of 1.56/cm.G10 Direction 5195795-100, Rev. 1, Copyright 2006 by GE HealthcareInfinia + Hawkeye 4 Users Guide

5. Click the [Proceed] button; to save the setup, open File menu and select Save and Exit.

FILTERS Pre-Filter type For Optimal Images: select the reconstruction filter that will produce best results or use the same parameters as for ACR accreditation

CORRECTIONS OPTIONS

Attenuation Correction Change order 0

Threshold Adjust until an optimal attenuation correction is achieved. Resulting transaxial projection should appear uniform, without "hot" central spots and/or edges. Typical values: Threshold = 5, coefficient = 0.12.

Coefficient

Acquiring & Processing Jaszczak Phantom Data SPECT Reconstruction Direction 5195795-100, Rev. 1, Copyright 2006 by GE Healthcare G11Infinia + Hawkeye 4 Users Guide

Figure G-6 Reconstruction Filter Selection (Hann 1.56 filter with attenuation correction threshold = 5 and coefficient = 0.125 shown)

Analysis Acquiring & Processing Jaszczak Phantom Data

Analysis

The procedure below describes the necessary steps required for analyzing and processing the acquired images.

1. From the Xeleris database list, select saved Results Series\TRANSAXIAL group and launch Load to New.G12 Direction 5195795-100, Rev. 1, Copyright 2006 by GE HealthcareInfinia + Hawkeye 4 Users Guide

2. Arrange the screen as shown in Figure G-7, so that all slices from the cold rods region of the phantom are represented on the upper sub-screen.

3. Select from the 16 slices from the central part of the cold rod section, which look similar. Record the first and last numbers of selected slices.

Figure G-7 Screen Arrangement for Resolution Analysis

Acquiring & Processing Jaszczak Phantom Data Analysis

4. Sum selected slices using Image Reframe Composite option. The output image represents a 5 cm (not pixel) thick section and is used to evaluate tomographic spatial resolution. See Figure G-8 Direction 5195795-100, Rev. 1, Copyright 2006 by GE Healthcare G13Infinia + Hawkeye 4 Users Guide

5. Adjust windowing levels for optimal visualization of the rods on the composed image.

z For typical results obtained using the ACR accreditation guidelines, see Figure G-9.

z For typical results obtained using the Optimal images guidelines, see Figure G-10.

Figure G-8 Phantom Image Analysis

Analysis Acquiring & Processing Jaszczak Phantom DataG14 Direction 5195795-100, Rev. 1, Copyright 2006 by GE HealthcareInfinia + Hawkeye 4 Users Guide

Figure G-9 Typical Resolution Image Obtained Using ACR Accreditation Guidelines

Acquiring & Processing Jaszczak Phantom Data Analysis Direction 5195795-100, Rev. 1, Copyright 2006 by GE Healthcare G15Infinia + Hawkeye 4 Users Guide

Figure G-10 Typical Resolution Image obtained using Optimal Image Guidelines


The image in Figure G-9 was obtained using the following acquisition parameters:

Table G-5: Acquisition Parameters

Isotope: Tc99m

Collimator LEHRG16 Direction 5195795-100, Rev. 1, Copyright 2006 by GE HealthcareInfinia + Hawkeye 4 Users Guide

The image in Figure G-10 was obtained using the following acquisition parameters:

6. Select the resulting image. From the File menu select Save. Name the image RESOLUTION when prompted and save it.



Detector radius 20.0

Average rate during persistence ~7 kcts/sec

Injected activity ~15 mCi Tc99m

Stop on time per projection 29 sec

Zoom 1.33

Reconstruction filter Metz 1.56

Attenuation correction Change order 0, threshold: 5, coefficient 0.125

# of summed slices 16

Table G-6: Acquisition Parameters

Isotope: Tc99m

Collimator LEHR



Detector radius 16.4

Average rate during persistence ~6 kcts/sec

Injected activity ~13 mCi Tc99m

Stop on time per projection 167 sec/projection

Zoom 1.33

Reconstruction filter Metz 1.56

Attenuation correction Change order 0, threshold: 5, coefficient 0.125

# of summed slices 16


7. Arrange the screen as shown in Figure G-7, but so that slices from the center of region with a uniform solution (without spheres or rods) are represented on the upper sub-screen.

8. Select up to 6 slices, which look similar. Record the first and last numbers of the selected slices.

9. Sum selected slices using Image Reframe Composite option (see Direction 5195795-100, Rev. 1, Copyright 2006 by GE Healthcare G17Infinia + Hawkeye 4 Users Guide

Figure G-11). The output image represent a ~2 cm (not pixel) thick section, that is used to evaluate uniformity.

10. Optimize the windowing levels of the composed image.

Figure G-11 Composed UNIFORMITY Image ACR accreditation Guidelines


11. Select the resulting image. From the File menu select Save, name the image UNIFORMITY when prompted and save it.

12. Arrange the screen as it is shown in Figure G-7, such that slices that contain the spheres are represented on the upper sub-screen.

13. Select from uniform region 2 slices, which look similar. Record the first and last numbers of selected slices for further reporting. G18 Direction 5195795-100, Rev. 1, Copyright 2006 by GE HealthcareInfinia + Hawkeye 4 Users Guide

14. Sum selected slices using Image Reframe Composite option (see Figure G-12). The output image represents the image with highest contrast, that is used to evaluate image contrast.


.Direction 5195795-100, Rev. 1, Copyright 2006 by GE Healthcare G19Infinia + Hawkeye 4 Users Guide

15. Optimize the windowing levels of the composed image.

Figure G-12 Composed CONTRAST Image - ACR Accreditation Guidelines


16. Verify that it is possible to position a horizontal line across the image (passing through its center) so that it does not touch any of the "cold" spheres. If needed, rotate the image a little using the Orientation option from the Image menu, as shown in Figure G-13. Use the scroll-bar marked on the illustration by red arrows. G20 Direction 5195795-100, Rev. 1, Copyright 2006 by GE HealthcareInfinia + Hawkeye 4 Users Guide

17. Select the resulting image. From the File menu select Save, name the image as CONTRAST when prompted, and save it. Close Workspace.

18. Re-open saved CONTRAST image and arrange 2x2 screen format.

Figure G-13 Rotation of image for CONTRAST Image


19. From the Curve menu, select Profile option.

20. Set profile parameters as shown in Table G-7

Table G-7 Profile Parameters

Input window ADirection 5195795-100, Rev. 1, Copyright 2006 by GE Healthcare G21Infinia + Hawkeye 4 Users Guide

21. Estimate and record the average counts number inside the phantom on the profile data.

22. Close the option by clicking the [Apply & Quit] button.

Output window B

Thickness (pixels) 1

Using Position (pixels) scroll-bar

Place the profile line across the center of the CONTRAST image without intersecting any sphere. The profile line should extend well outside the phantom on both sides


Figure G-14 Profile Parameters Setting


23. Re-open the Profile option. Set profile parameters as shown in Table G-8:

Table G-8 Profile Option

Input window A

Output window CDirection 5195795-100, Rev. 1, Copyright 2006 by GE Healthcare G23Infinia + Hawkeye 4 Users Guide

Thickness (pixels) 1

Using Position (pixels) scroll-bar

Place the profile line so that it crosses the center of biggest "cold" sphere. Estimate and record the minimum number of counts in the profile within the phantom.


Figure 12:

24. Calculate the contrast as:

Contrast = (Average_Cnts - Minimum_Cnts)/Average_Counts

Record calculated contrast value for further reporting.

Figure G-15 Contrast Measurements


25. Repeat steps 1 -24 for the SPECT data obtained with the Jaszczak phantom filled with Tl201 or Ga67.Direction 5195795-100, Rev. 1, Copyright 2006 by GE Healthcare G25Infinia + Hawkeye 4 Users Guide

Start Page Cover Pages Preface Table of Contents List of Figures Safety & Regulatory System Components & Features System Power-up and Shutdown Daily Routine Collimators and Collimator Exchange Patient Study Workflow Acquisition Data Management Emergency Procedures Quality Control Troubleshooting System Maintenance System Setup Image Viewer User Interface Hawkeye 4 Option CoDe VC Option Acquisition Parameters Factory Protocols Pinhole Collimator Acquiring & Processing Jaszczak Phantom Data Overview Phantom Description

System Preparation Phantom Adjustment Gantry Setup Jaszczak Phantom Preparation SPECT Acquisition Using Tc99m With LEHR Collimators SPECT Acquisition Using Other Radioisotopes and Collimators

Tomo Image Acquisition SPECT Reconstruction Analysis

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g-jaszczak phantom data

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