quality assurance procedure for srs and …€¦ · misconfiguration of tps software bugs...

QUALITY ASSURANCE PROCEDURE FOR

SRS AND SRT TREATMENTSMEIJERS A., PLAUDE S., UTEHINA O., POPOVS S.

RIGA EAST UNIVERSITY HOSPITAL

Thursday, October 13, 11

SRS / SRT TREATMENTS

INTRODUCED IN 2009 AT RIGA EAST UNIVERSITY HOSPITAL.

EQUIPMENT:

NOVALIS TX (VARIAN), EXACTRAC (BRAINLAB)

VARIOUS LOCALIZATIONS:

HEAD, LIVER ETC.


CHALLENGES

FRACTIONATED TREATMENT

1 - 5 GY PER FRACTION10 - 39 FRACTIONS


CHALLENGES



CHALLENGES


MISTREATMENT OF A SINGLE FRACTION DOES NOT HAVE SIGNIFICANT IMPACT ON DELIVERED DOSE


CHALLENGES

RADIO-SURGERY

4 - 20 GY PER FRACTION1 - 3 FRACTIONS


CHALLENGES

RADIO-SURGERY


CHALLENGES

RADIO-SURGERY

MISTREATMENT IN A SINGLE FRACTION HAS SIGNIFICANT IMPACT ON ALL THE TREATMENT


TREATMENT ACCURACY

SRSSRT

FRACTIONATEDTHERAPY

SRS / SRT REQUIRES HIGHER QUALITY IN TERMS OF TREATMENT DELIVERY


TREATMENT ACCURACY

SRS / SRT REQUIRES EXTENDEDQUALITY ASSURANCE PROCEDURE


CAUSES OF INACCURACY

PATIENT POSITIONING

MISCONFIGURATION OF TPS

SOFTWARE BUGS

MECHANICAL FAULTS OF TREATMENT DELIVERY SYSTEM

MIS-CALIBRATION OF LINAC

IONIZATION CHAMBERS

MECHANICAL INDICATORS


POSITION UNCERTAINTIES

EXACTRAC (BRAINLAB)


QUALITY ASSURANCE

HARDWARERELATED

PATIENTRELATED


PATIENT-RELATED QA FOR SRS/SRT

DOSE PLANE MEASUREMENT

ABSOLUTE POINT-DOSE MEASUREMENT

WINSTON-LUTZ TEST



1. CALCULATION OF TREATMENT PLAN ON QA PHANTOM

2. MEASUREMENT WITH RADIOCHROMIC FILM

3. COMPARISON OF MEASURED DOSE VS CALCULATED


FILM DOSIMETRY

GAFCHROMIC EBT 2 (ISP) FILMS

DOSE RANGE UP TO 40 GY

CALIBRATION: TEST FILM WITH KNOWN DOSE

METHOD: COMPOSITE ANALYSIS

0

7.5

15.0

22.5

30.0

1 10 100 1000

Dose

, Gy

Tone Index


FILM DOSIMETRY

ANALYSIS:

GAMMA INDEX - 1MM / 5% / SUPPRESS < 5%

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'&25�BBBBBBBBBB

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6WDWLVWLFV1XPEHU�RI�'RVH�3RLQWV ��(YDOXDWHG�'RVH�3RLQWV �� 3DVVHG �� )DLOHG �� 5HVXOW �� *UHHQ�

*DPPD��'$ULWKPHWLF�0HDQ ��0LQ �� /5 � �� PP�� 7* � �� PP� ��0D[ �� /5 � �� PP�� 7* � �� PP� ��0HGLDQ ��

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6HWWLQJV3DVVLQJ�FULWHULD *DPPD��*UHHQ �� WR ��<HOORZ �� WR �� 5HG �� WR ��

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'DWH 1DPH�DQG�)XQFWLRQ 6LJQDWXUH

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'&25�BBBBBBBBBB

*DPPD��'��3DUDPHWHUV�� PP�'LVWDQFH��7R��$JUHHPHQW�� 'RVH�'LIIHUHQFH�ZLWK�UHI��WR 0D[��GRVH�RI�PHDVXUHG�GDWD�VHW8VH�LQFUHDVHG�WROHUDQFH�RI �� 'RVH�'LII��IRU�YDOXHV�EHORZ �� *\��RU�$8�6XSSUHVV�GRVHV�EHORZ �� RI�PD[��GRVH�RI�PHDVXUHG�GDWD�VHW

6WDWLVWLFV1XPEHU�RI�'RVH�3RLQWV ��(YDOXDWHG�'RVH�3RLQWV �� 3DVVHG �� )DLOHG �� 5HVXOW �� *UHHQ�

*DPPD��'$ULWKPHWLF�0HDQ ��0LQ �� /5 � �� PP�� 7* � �� PP� ��0D[ �� /5 � �� PP�� 7* � �� PP� ��0HGLDQ ��

$EVROXWH�'LIIHUHQFH$ULWKPHWLF�0HDQ �� *\0LQ �� /5 � �� PP�� 7* � �� PP� �� *\0D[ �� /5 � �� PP�� 7* � �� PP� �� *\0HGLDQ �� *\

6HWWLQJV3DVVLQJ�FULWHULD *DPPD��*UHHQ �� WR ��<HOORZ �� WR �� 5HG �� WR ��

,�KHUE\�FRQILUP�WKDW�,�KDYH�FKHFNHG�DOO�GDWD�PHQWLRQHG�DERYH�DQG�WKDW�WKH�UDGLRORJLF�WUHDWPHQW�DFFRUGLQJ�WKLV�GDWD�VKDOO��VKDOO�QRWSURFHHG�

'DWH 1DPH�DQG�)XQFWLRQ 6LJQDWXUH

37:��9HUL6RIW�� 3DWLHQW,'�� 3DWLHQW�1DPH��7HUHVNRYLFD��1LQD 'DWH��

ACCEPTABLE:GAMMA PASS > 90%

UNACCEPTABLE:GAMMA PASS <85%

MEAN 96.4 ± 2.6 %





WINSTON-LUTZ TEST


POINT DOSE MEASUREMENT

1. CALCULATION OF TREATMENT PLAN ON QA PHANTOM

2. MEASUREMENT WITH IONIZATION CHAMBER

3. COMPARISON OF MEASURED DOSE VS CALCULATED


POINT DOSE MEASUREMENT

HAND-MADE PHANTOMPINPOINT CHAMBER (PTW)

0.016 CM3

ANALYSIS:LOCAL DIFFERENCE IN %

ACCEPTABLE < 3%UNACCEPTABLE > 5%

MEAN -1.2 ± 1.6 %





WINSTON-LUTZ TEST


WINSTON-LUTZ TEST

1. ALIGN POINTER TO ISOCENTRE

2. TAKE PORTAL IMAGES FROM NECESSARY ANGLES

3. DETERMINE CENTRE OF FIELD

4. DETERMINE CENTRE OF POINTER SPHERE

5. DETERMINE THE DISTANCE BETWEEN CENTERS


WINSTON-LUTZ TEST

ACCEPTABLE < 1MMUNACCEPTABLE > 1MM

0.50

0.75

1.00

Sphe

re s

ize, m

m





WINSTON-LUTZ TEST


CONCLUSIONS

THE DEVELOPED PATIENT RELATED QA PROCEDURE IS SUFFICIENT TO VERIFY ACCURACY OF TREATMENT PLANNING SYSTEM CALCULATIONS, PRECISION OF TREATMENT DELIVERY MECHANICS AND SYSTEM IN GENERAL.

ADDITIONAL MACHINE RELATED VERIFICATIONS ARE NECESSARY.

QA PROGRAM, BASED ON DESCRIBED PRINCIPLES, HAS BEEN IMPLEMENTED IN RIGA EAST UNIVERSITY HOSPITAL.


THANK YOU!

[email protected]


mailto:[email protected]

mailto:[email protected]

quality assurance procedure for srs and …€¦ · misconfiguration of tps software bugs...

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