helical tomotherapy quality...

Helical Tomotherapy Quality Assurance

Cheng Shi PhDChengyu Shi, PhDDepartment of Radiation Oncology

Di i i f M di l Ph iDivision of Medical Physics

Southwest Chapter of the AAPM, Oct 9, 2009

ObjectivesObjectives• To introduce our five-year clinical experience

ith helical TomoTherapwith helical TomoTherapy• To introduce our five-year research experience

with helical TomoTherapy

There is no conflict of interestThere is no conflict of interest

IGRT SolutionIGRT SolutionImaging

Ionizing Non-ionizing

CT Ultrasound MRIX-ray

PETSPECT RF Laser

OthersOthers

IGRT QAIGRT QA• IGRT solution introduces precise targeting

• However, it may also introduce more uncertainties and increased risk to miss the targetg

• Therefore, comprehensive QA procedures are necessary

• Helical Tomotherapy has its own characteristics• Helical Tomotherapy has its own characteristics, and requires dedicated QA protocol

Helical TomoTherapy QAHelical TomoTherapy QA

QA

System PatientSystem Patient

Hardware Software Planning Delivery

Helical Tomotherapy ProcessHelical Tomotherapy ProcessR i d i

MVCTRegistered image

MVCT Guided

Image registration

Helical CT Delivery

Helical Tomotherapy SystemHelical Tomotherapy System

Hardware Software

Helical Tomotherapy QA DesignHelical Tomotherapy QA Design

Component-based: QA each component, h MLC d t t h tsuch as MLC, detector, couch etc.

System based: QA the whole systemSystem-based: QA the whole system performance

I am NOT good I am good

Helical Tomotherapy QAHelical Tomotherapy QA

Chester Ramsey, et al. "Mechanical and Dosimetric Quality Assurance for Helical Tomotherapy," International Journal of Radiation Oncology Biology Physics, 1 November 2007 (Vol. 69, Issue 3, Page S699)

TomoTherapy Daily QA PerformanceTomoTherapy Daily QA Performance

Helical Tomotherapy Target IssueHelical Tomotherapy Target Issue

Eroded target Rusted on-board ion chamber

Helical Tomotherapy Working ZonesHelical Tomotherapy Working Zones

VPFN VIC Dose Rate RelationshipVPFN, VIC, Dose Rate Relationship

Helical Tomotherapy MLC QAHelical Tomotherapy MLC QA

Special MLC QA for Helical Tomotherapyp py

S h b d i dSeven test patterns have been designed

A. Box in BoxB. Modified Checkerboard. od ed C ec e boa dC. MLC Interleaf LeakageD IEC X gradientD. IEC-X gradientE. IEC-Y gradientF C l Fi ld A (2 t t )F. Complex Field A (2 tests)G. Complex Field B (2 tests)

Pattern A. Box in boxPattern A. Box in box

A. Box in BoxPattern A Box in box. o oPattern A. Box in box

Pattern B. Modified checkerboxPattern B. Modified checkerbox• Can be thought as small box in box testg• Initially used for Mimic MLC test• Modified for tomotherapy MLC testpy

Pattern B Modified checkerboxPattern B. Modified checkerbox

Pattern C Inter leaf LeakagePattern C. Inter leaf Leakage

Pattern D. IEC-X GradientPattern D. IEC X GradientPNMW depthnormwedge PNMW ••=

PNMW ••= depthnormwedge PNMW ••=

Pattern E. IEC-Y GradientPattern E. IEC Y Gradient

PNMW depthnormwedge PNMW ••=

Pattern F. Complex APattern F. Complex A

Pattern G. Complex BPattern G. Complex B

MVCT QAMVCT QA

3% contrast

1 6 mm resolution1.6 mm resolutionCT-density table consistency

Helical Tomotherapy TQATMHelical Tomotherapy TQA

Tomotherapy Patient-Specific QATomotherapy Patient Specific QA

QA Equipment

Generate QA procedure

Deliver QA procedure

Analysis QA procedure

Evaluate QA procedure

QA EquipmentQA Equipment

Cheese Homo Phantom

EDR2 Film

A1SL Ion Chamber

Deliver QA procedure-PatientDeliver QA procedure Patient

PhantomRed lasers

Chamber

EDR2 film

Deliver QA procedure-CalibrationDeliver QA procedure Calibration

Analysis QA procedure-Absolute dosey p

Excel sheet for dose measurement

What if the QA fails?Q

Find out why?

Phantom resolution? High dose gradient? Small thin PTV? Machine output? …

Repeat the QA procedure

Example-Overweightp g

•Patient with prostate cancer (weight 370 lb)•Tomotherapy couch can support ~440 lb.•Patient plan is homogeneous for PTVp g•Phantom size is very different from patient size resulting to non-homogenous dose at thesize, resulting to non-homogenous dose at the point of the chamber

Example-Overweight

25.90 cm

Example-Overweightp g

3 88% here

15.50 cm

3.88% here

6.22% here

Delta 4 Dosimeter for Tomo

• Purchased September 2008TomoTherapy OptionRapidArc Option

Fi t f th• First few monthsResearchSBRT QASBRT QA

• Mid‐January 2009Fully clinical for tomotherapy DQA

• Absolute calibrate on T ThTomoTherapy

• Phantom MVCT image for planningplanning

Delta 4 Dosimeter ResultsDelta 4 Dosimeter Results• 140 DQAs delivered Q

on Delta4

• 34 SBRT patients with gamma index > 95% (3%/3mm)

• Pass criteria3%/3mm

90%>90% gamma

• To date,Mean gamma: 97 1%Mean gamma: 97.1% (85.9‐100)

MVCT VerificationMVCT Verification

MVCT Verification

Setup UncertaintiesSe up U ce a es

DiscussionDiscussion

T th i li bl l l ti lt d it h ld• Tomotherapy gives reliable calculation results, and it should be within 3% tolerance about dose measurement for most of casescases

• EDR2 is a good tool for relative and absolute dose measurementmeasurement

• Gamma factor is a good evaluation parameter

• Some QA cases need more analysis

• QA is a little hard to do in some cases such as spine andQA is a little hard to do in some cases such as spine and lung SBRT

Tips or Problems you may meetTips or Problems you may meet

• Scanning QA phantom with different resolution and extension

P t i h b i t h it i f th PTV• Put ion chamber into homogeneity region of the PTV

• Use high resolution phantom for smaller or thinner PTV

• You can extend EDR2 film range up to 600~700 cGy, however, that is for relative dose measurement only. For absolute dose measurement using film, you can do it under 400 cGy, and it should be good for normal treatment procedure.

• Delta 4 dosimeter is a good candidate for Tomo QA

S R h T l D l tSome Research Tools Development

Design algorithmDesign algorithm

Hardware related• Target changeTarget change• Jaw• MLC• MLC…Software related• Composite plan• DVH…Clinical/Research need• Archive patientArchive patient…

Design languageDesign language

Excel VBA for clinicalMatlab for researchMatlab for researchVisual c++ for fast applicationXML, html

Tools we have developedTools we have developed

ToPinnacleTomoBinTomoBinTomoAnnualTomoGkPinnacleTomo-XML-DOMTomo-XML-DOMExcel sheets

ToPinnacleToPinnacle

Need: Physicians need plan comparison between Tomotherapy and Pinnacle andbetween Tomotherapy and Pinnacle and composite plan

Design: Visual c++ program to transfer dose matrix data from Tomotherapy tomatrix data from Tomotherapy to Pinnacle

ToPinnacleToPinnacle

TomoBin

Need: Tomo procedure needs sinogram d bi MLC d QAand binary MLC needs QA

Design: Matlab program to design tomotherapy MLC patterntomotherapy MLC pattern

How were the patterns designed?How were the patterns designed?

Consider dose and mechanical factorsSeven patterns (9 tests) have been designeddesignedA software platform is also designed to

t d l th ttgenerate and analyze the patternsThe patterns can be transferred easilyThe patterns can be transferred easily to other centers with a helical tomotherapy unittomotherapy unit

TomoAnnualTomoAnnual

Need: How to compare commission data with annual QA data? How to predict ptarget failure?

Design: Matlab program to use commissionDesign: Matlab program to use commission data as baseline for monthly and annual

fprofile comparisonC Shi S Stathakis N Papanikolaou “Development and application of aC Shi, S Stathakis, N Papanikolaou, Development and application of a platform for analyzing helical tomotherapy annual and monthly profiles,” the XVth International Conference on the Use of Computers in Radiation Therapy Toronto Canada June 4 7 abstract # 6102 (2007)Therapy, Toronto, Canada, June 4-7, abstract # 6102 (2007).


Profiles collected for theprevious target a-d and after thetarget replacement etarget replacement e.

The angle difference between two profiles for d) is around 1 degree.

TomoGkPinnacleTomoGkPinnacle

Need: for research use; how to transfer data from one planning station to another?p g

D i M tl b t t dDesign: Matlab program to convert dose matrix between different TPS

C Shi, J Penagaricano, Y Yan, N Papanikolaou, “Application of the Post-Processing Dose Tool (PPD) to Dosimetrically Compare Gamma Knife andProcessing Dose Tool (PPD) to Dosimetrically Compare Gamma Knife and Hi Art Tomotherapy,” SU-FF-T-101, AAPM 48th Annual Meeting (2006)

TomoGkPinnacleTomoGkPinnacle

TomoGkPinnacle->APT4DTomoGkPinnacle >APT4D

Lan Lin, Chengyu Shi, Gregory Swanson, Nikos Papanikolaou, "Development of a Novel Post-processing Treatment Planning Platform for 4D Radiotherapy," Technology in Cancer Research and Treatment (April 2008)Technology in Cancer Research and Treatment (April 2008)

Tomo-XML-DOMTomo XML DOM

Need: how to extract necessary information from tomotherapy plan to perform a 2nd check?p

Design: XML language to extract archived patient informationarchived patient information

T Roland CY Shi N Papanikolaou "Development and application of aT Roland, CY Shi, N Papanikolaou, Development and application of a robust toolkit, Tomo-XML-DOM, for helical tomotherapy system," Submitted to 50th AAPM Annual Meeting (2008)

Tomo-XML-DOMTomo XML DOM

Tomo Patient QA 2nd CheckTomo Patient QA 2 Check

Excel sheetsExcel sheets

Need: daily, monthly, annual QA, patient setup, QA…p,

D i l VBADesign: excel VBA

Excel sheets-Annual QAExcel sheets Annual QA

AAPM TG 148 in-progressAAPM TG 148, in progress

Where do we go?Where do we go?

• System-based QA vs. component-based QA

• Internet QA with intra/inter institution comparison

• Risk estimation for failure rate and prediction

S lf QA hi d QA• System self QA vs. third-part QA

SummarySummary

• Current Helical Tomotherapy QA Status is component-based QA and varies from center to p Qcenter

• Future implementation of Helical Tomotherapy QA maybe system-based, internet-based, risk-Q y y , ,estimation, and system-self QA

• AAPM TG 148 will provide recommendations for QA tests and frequency of testingQ q y g

AcknowledgementsAcknowledgements

• Dr. Papanikolaou• Dr GutierrezDr. Gutierrez• Dr. Lan Lin• Dr. Fan-Chi (Frances) Su• Dr Vikren SarkarDr. Vikren Sarkar• Roland Teboh• Weihong He• Luis Vazquez Quino• Luis Vazquez Quino

E il hi @ h dEmail: [email protected]

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