Section 1 Introduction V Rjo 081007 W Presenter Created Quiz

July 2007 Copyright © Siemens AG 2007. All rights reserved.

Section 1:Section 1:IntroductionIntroduction

Siemens Medical Solutions, Inc.Oncology Care Systems Group4040 Nelson AvenueConcord, CA 95420

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MVision Physicist Self-Led TrainingMVision Physicist Self-Led TrainingRev. C


Section Guide

Section 1: Introduction and Preview

Section 2: Cone Beam Geometry Calibration

Section 3: Image Quality QA

Section 4: Adaptive Targeting


Section 1: ObjectivesSection 1: Objectives

At the completion of this section, you will be able to:

Identify the fundamentals of MVision

List the physicist calibration and QA tasks related to MVision

Perform flat panel 2D gain calibration


Section 1: Table of ContentsSection 1: Table of Contents

Overview

Performance Parameters

Target Monitor Units

Beam Tuning Comparison

Acquisition Time

MVision Advantages

Looking Ahead

Physicist QA Tasks

New Tools for MVision

MVision QA and Maintenance

Section 1 Review

Section 1 Quiz

Lab: 2D Gain Calibration


MVision OverviewMVision OverviewMVision imaging is the process of: Acquiring 2D images Reconstructing a 3D image data set

from the 2D images Advantages: Patient Imaging and treatment on the

same machine Quick comparison between the CT plan

images to the MVision images prior treatment

Adapt the patient CT plan as necessary

At each arc increment, a

small amount of dose is

delivered to acquire one

frame of MVision

images

The Gantry moves at a

constant speed as it

does in an arc

treatment

MVision arc

starts here

(270°)

MVision arc

ends here

(110°) completing

the acquisition

Figure 1.0


MVision OverviewMVision Overview Product goals Workflow integration Syngo imaging platform Improve patient positioning accuracy by

using 3D space Use of the existing equipment (LINAC

Flat Panel, syngo workstation) Secondary imaging system not required

At each arc increment, a

small amount of dose is

delivered to acquire one

frame of MVision

images

The Gantry moves at a

constant speed as it

does in an arc

treatment

MVision arc

starts here

(270°)

MVision arc

ends here

(110°) completing

the acquisition

Figure 1.0


MVision Performance ParametersMVision Performance ParametersParameter Value

CT number range -1000 to +3095

CT number accuracy ±40 HU: The shift of the mean (from expected value of

0 HU) in the center 2 cm ROI within a 20 cm solid water

equivalent

CT number uniformity 60 HU (cupping effect): Difference between maximum

intensity of regions in the periphery and the central

region

Spatial resolution 0.3 lp.mm: Measured with 1.0 mm voxel reconstruction

Table 1.0


Parameter Value

Low contrast resolution 5%: 2 cm diameter region is visible with 5 mm slice

thickness with 10 cGy dose

Noise 4%: with 10 cGy dose: Measured in the 2 cm ROI within

a 17.5 cm diameter solid water phantom

Reconstruction field-of-view 27 cm diameter in transaxial slices; 27 cm in the axial

direction

Reconstruction matrix size 128 x 128, 256 x 256, 512 x 512

MVision Performance ParametersMVision Performance Parameters

Table 1.0


Parameter Value

Slice thickness From as small as 1.4 mm minimum up to arbitrary

thickness by means of thick MPR

Acquisition reconstruction and

auto-registration time

Typically 2.5 min for acquisition and reconstruction;

typically 3 min for acquisition, reconstruction and auto-

registration for 256 x 256 x 270

Geometry accuracy <1 mm: This is defined by how well distance can be

measured within the scanned volume

MVision Performance ParametersMVision Performance Parameters

Table 1.0


MVision Target Monitor UnitsMVision Target Monitor Units

MVision preset MU

Target MU = (MVision preset

MU x 0.9)

Target MU = (MVision preset MU

x 0.9) - 5%

Target MU = (MVision preset MU x 0.9) + 5%

3 2.7 2.56 2.83

5 4.5 4.275 4.725

8 7.2 6.84 7.56

10 9 8.55 9.45

15 13.5 12.82 14.17

18 16.2 15.39 17.01

20 18 17.1 18.9

40 36 34.2 37.8

60 54 51.3 56.7

Table 1.1

MVision target monitor units


Beam Tuning ComparisonBeam Tuning Comparison

Regular 6MV 50MU/Min

MVision 6MV 50MU/Min

Lower Dose per pulse

Higher radiation pulse repetition frequency~ 4 ms

Higher Dose per pulse

Lower radiation pulse

repetition frequency~ 24 ms

Same radiation pulse

time duration~ 3.4s

Figure 1.1


Acquisition TimeAcquisition Time

For each projection image

Figure 1.2

//

//

Rad On time

Beam Integration for dosimetry& transmit to Control Console

FP Readout

Safety margin for non-smooth gantry motion

Total time for acquisition of one projection image

Gantry Position 1 Gantry Position2


MVision AdvantageMVision Advantage

Minimizes artifacts caused by dental implants

Kilovoltage CTKilovoltage CT MVisionMVision

With courtesy from:J. Pouliot, UCSFWith courtesy from:J. Pouliot, UCSFFigure 1.3 - a Figure 1.3 - b


MVision AdvantageMVision Advantage

Minimizes artifacts caused by metal prostheses

With courtesy from: J. Pouliot, UCSFWith courtesy from: J. Pouliot, UCSFFigure 1.4


Looking AheadLooking Ahead

Exit Dosimetry

Import MVision images in the TPS to calculate actual dose distribution

With courtesy from: J. Pouliot, UCSF, April 29, 2005 Stanford IGRT Short CourseWith courtesy from: J. Pouliot, UCSF, April 29, 2005 Stanford IGRT Short CourseFigure 1.5


MVision Physicist QA TasksMVision Physicist QA Tasks

Figure 1.6 Perform MVision

Geometry Calibration

Create or update

MVision Protocol

Perform MVision Gain

Calibration

Perform Flat Panel

Alignment QA

Perform 2D

Gain Calibration

Perform MVision

Image QA

Physicist tasks include:


MVision Physicist QA TasksMVision Physicist QA Tasks

Perform MVision

Geometry Calibration

Perform MVision Gain

Calibration

Perform Flat Panel

Alignment QA

Perform 2D

Gain Calibration

Physicist tasks include:

Create or update

MVision Protocol

Perform MVision

Image QA

Figure 1.6


Tools for MVisionTools for MVision

Figure 1.7b

Figure 1.7a

OPTIVUE 1000 ST Flat Panel


Tools for MVisionTools for MVisionOPTIVUE 1000 ST Flat Panel

Figure 1.8

Scintillator

Incident X-rays

Capacitive

Storage

Element

Visible Light

+ + + + + + + Electrical Charge

Photodiode

Digital Image

Charge Readout and Analog

to Digital Signal

Conversion


Tools for MVision Tools for MVision

Table 1.2

FEATURE OPTIVUE 1000ST Specifications

Detector weight (Kg) 23

Detector size (mm) 672 x 599 x 44

Active detection area (cm2) 41 x 41

Maximum acquisition rate (fps) 7 frames per second

Image display time Near real time

Detector efficiency (port only) Max recommended dose: 3 MU

Detector non-linearity<±2% for free-run acquisition

<±3% for triggered acquisition

1. These are minimum specifications; below these values, the detectors are rejected.

2. As measured using the PIPSpro QC-3V phantom.


Tools for MVision Tools for MVision

Table 1.2

FEATURE OPTIVUE 1000ST Specifications

Detection method Indirect

Matrix size (pixels) 1024 x 1024

Pixel size (µm) 400

Pixel bit depth 16 bits

Spatial resolution (f50 in lp/mm)1 ≥0.41 lp/mmm at 6MV

Contrast/noise ratio 1, 2 (port during) ≥600 @ 50 MU (1024 x 1024)

Contrast/noise ratio 1, 2 (port only) 125 @ 1 MU (1024 x 1024)

1. These are minimum specifications; below these values, the detectors are rejected.

2. As measured using the PIPSpro QC-3V phantom.


Tools for MVisionTools for MVisionService Patient

Used to perform MVision and 2D imaging calibration tasks

Site Name Purpose Physicist Task Siemens Service Task

Calibration Gain-SID1 2D Gain Calibration

Calibration-Other 1.52 Dead Pixel Map Calibration

Calibration-Other 2.03Dead Pixel Map Calibration, MVision Gain

Calibration and Geometry Calibration

FlatPanelAligment Flat panel alignment calibration for 2D imaging

FlatPanelAligment CB Flat panel alignment calibration for MVision imaging

1 Each gain site assumes a different SID value : 120, 130, 140, 145, 150, 155 and 160 cm

2 Not used for MVision users

3 Physicist should only perform MVision Gain Calibration and Geometry Calibration

Table 1.3


Tools for MVisionTools for MVisionService Patient

Figure 1.9


Tools for MVisionTools for MVisionImage Quality Patient

Used to perform MVision and 2D Imaging QA tasks

Site Name Purpose Physicist Task Siemens Service Task

Image QA Create MVision Fields for Image QA and acquire

the Flat Panel alignment QA images1

OPTIVUE ATP: AG9 Perform 2D Image Quality ATP for AG9 (1000ST)

Flat Panel

OPTIVUE ATP: AL7 Perform 2D Image Quality ATP for AL7 Flat Panel

UniformitySet1B, 2B

and 3B : AG9Perform AG9 Flat panel image uniformity check

UniformitySet1B, 2B

and 3B : AL7

Perform AL7 Flat panel image uniformity check

1 Siemens service will acquire a reference image for the flatpanel alignment QA during MVision tune-upTable 1.4


Tools for MVisionTools for MVisionImage Quality Patient

Figure 1.10


XRETIC Crosshair Reticule

Fits in Slot 3 of the machine accessory holder

Is used to:

Perform flat panel alignment QA

Set image quality phantom alignment

Perform flat panel alignment calibration (Siemens service only)


Figure 1.11



Figure 1.12

XRETIC Calibration

The physicist may check the

XRETIC calibration using the

Lab7 XRETIC Calibration Check

Product label

Tungsten wire (2 extra wires are delivered with product)

Digital resistor plug (Siemens code XRETIC)

Wire tension and position adjustment


Flat panel alignment QA

The XRETIC reticule and the Image Quality patient are used to perform this check

Deliver the Daily QA port only field using the site Image QA and check

Visually inspect the alignment of the image with the Coherence green crosshair

Measure the offset between green crosshair and acquired image

Recommended Frequency: Daily

Tolerance: ±1mm

MVision QA and MaintenanceMVision QA and Maintenance

Figure 1.13


Flat panel alignment QA

If the measured offset is larger than ±1mm the physicist may check

XRETIC calibration

Light versus Radiation Field coincidence

If corrections are needed on either of the above please contact Siemens Service


Figure 1.13


2D Gain Calibration

Used to correct differences in the Flat Panel diodes behavior on 2D imaging

Service Patient is used to acquire Port During Gain fields at different Photon Energies, Dose Rates, Source to Imager Distances (SID), Monitor Units and Field Sizes

The 2D gain fields are grouped on different sites identified by different SID

Each site contains four gain fields (except for SID 120 which has two gain fields)



2D Gain Calibration

Physicists or Therapists may acquire the 2D Gain Fields Suggested 2D Gain Calibration frequency: every 2 Weeks Coherence Therapist prompts the user to re-acquire the 2D gains

every four weeks The gain files are overwritten every time a new gain calibration is

performed See Lab 1: 2D Gain Calibration for instructions on how to perform gain

calibration



MVision QA and MaintenanceMVision QA and MaintenanceFlat Panel 2D Gain Calibration

Figure 1.14


2D Gain History

To verify if the gains are up to date check the 2D gain history file “Gain_History.txt”


Figure 1.15


2D Gain Images Location

The 2D Gain images are stored at :

C:\Coherence\data\PortalImaging\Gain


Figure 1.16


MVision Beam Output Calibration

Physicist should calibrate the MVision beam output prior service engineer performing the dose scale factor (DSF) calibration

MVision beam tuning should be performed in the following order

Siemens installer performs MVision beam peaking to comply with MVision imaging requirements

Site Physicist performs MVision beam output calibration

Siemens Installer performs the Dose Scale Factor Calibration



MVision QA and MaintenanceMVision QA and MaintenanceControl Console pages used for MVision

Cone Beam Calibration Cone Beam Calibration is

used to visualize the dose

scale factor calibration

points

Softpots Softpots is used to

calibrate MVision beam

output

Figure 1.17


MVision QA and MaintenanceMVision QA and MaintenanceMVision dose page

DOSE SET 17 DOSE SET 17

is the dose

page used to

calibrate

MVision Beam

Output

CB-AJ is

displayed

when the

Cone Beam

dose page

is selected

D1_C0D1_C0 is not used

for MVision acquisitions

Figure 1.18


Cone Beam Calibration page


Dose Scale Factor Dose Scale Factor calibration

points. The smaller and the

larger monitor units values

represent the range of MU

allowed to scan patients with

MVision

Dose Margin Factor Dose Margin Factor is used as

an additional safety if the

MVision dose deviates by more

than 20%

Gantry Speed Factor Gantry Speed Factor is used to

fine tune the gantry speed for

optimal MVision acquisitionFigure 1.19


Section 1: ObjectivesSection 1: Objectives

Now that you have completed this section, you should be able to :

Identify the fundamentals of Mega Voltage MVision

List the physicist calibration and QA tasks related to MVision

Perform Flat Panel 2D Gain


Section 1: ReviewSection 1: Review

Performance Parameters

Target Monitor Units

Beam Tuning Comparison

Acquisition Time

MVision Advantages

Physicist QA Tasks

New Tools for MVision

MVision QA and Maintenance

During this self-led training, you have read through the following topics:


Section 1 Quiz


The primary goal of MVision is:

Correct - Click anywhere to continueCorrect - Click anywhere to continueIncorrect - Click anywhere to continueIncorrect - Click anywhere to continueYou must answer the question before continuingYou must answer the question before continuing

Submit ClearSubmit

A) Reconstruct a 3D image data set from 2D images

B) Position the patient more accurately

C) Spare critical organs

D) Increase the tumor dose

E) All of the above


The OPTIVUE 1000ST Flat Panel is called an indirect detector because it converts:

Submit Clear


A) X-ray into charge

B) Charge into current

C) X-ray into visible light

D) All of the above


Only the physicist should create or update an MVision protocol.

Submit Clear


A) True

B) False


What is the recommended frequency to perform 2D gain calibration?

Submit Clear


A) Every week as required

B) Every two weeks

C) Annually

D) If the Flat Panel Daily QA fails

E) B and D are correct


If the Daily Flat Panel QA is out of the +/- 1mm specification, the physicist should:

Submit Clear


A) Perform the Flat Panel alignment

B) Check the XRETIC calibration

C) Calibrate the XRETIC

D) Check the light to radiation field coincidence

E) B and D are correct


A 10MU MVision protocol is used to image a patient. The delivered (target) MU should be:

Submit Clear


A) 10MU

B) 9MU

C) Between 8.55MU and 9.45MU

D) 11MU


The MVision Beam Output Calibration should be checked by the physicist after the Service Engineer performs the Dose Scale Factor calibration.

Submit Clear


A) True

B) False


The MVision Physicist tasks include:

Submit Clear


A) 2D and MVision gain calibration

B) Create/Modify MVision protocols

C) Perform dead pixel map calibration

D) All of the above

E) A and B


Whenever performing the flat panel alignment QA, the user should:

Submit Clear


A) Check if the alignment image is within +/- 1mm of the Coherence green crosshair

B) Calibrate the XRETIC to acquire the alignment images

C) Use the Service Patient to acquire the alignment image

D) All of the above


To check the 2D gain history, one should:

Submit Clear


A) Acquire new gain files and open the Gain_History.txt file

B) Delete the Gain_History.txt file and acquire new Gains

C) Open the Gain_History.txt file

D) Calibrate the beam output prior and check the Gain files


The Physicist should use the Image Quality patient to:

Submit Clear


A) Perform flat panel uniformity check

B) Calibrate the MVision Image Geometry

C) Perform the flat panel alignment QA

D) Perform MVision Image QA

E) C and D are correct


The Physicist should use the Cone Beam Calibration to check if the dose scale factor points are within the MU range intended to scan patients and perform calibration tasks.

Submit Clear


A) True

B) False


The D1_C0 Softpot should be calibrated in order to:

Submit Clear


A) Get optimal dose delivery for MVision

B) Compensate for the beam formation time

C) Adjust the dose per projection image

D) Correct MVision beam output

E) It should not be calibrated


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Section 1 Introduction V Rjo 081007 W Presenter Created Quiz

Technology

Transcript of Section 1 Introduction V Rjo 081007 W Presenter Created Quiz