Dosimetry Audit in Radiotherapy, in Greece Costas J. Hourdakis, A. Boziari & V. Kamenopoulou Greek...
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Transcript of Dosimetry Audit in Radiotherapy, in Greece Costas J. Hourdakis, A. Boziari & V. Kamenopoulou Greek...
Dosimetry Audit in Radiotherapy, in Greece
Costas J. Hourdakis, A. Boziari & V. KamenopoulouGreek Atomic Energy Commission, EEAE
Athens, 12 September 2014
EFOMP Symposium,Athens -12 Sept 2014, ΕΕΑΕ, [email protected]
Regulatory Inspections
(Greek Atomic Energy Commission)
Management System Audits –
Accreditation Audits
Clinical Audits
Dosimetry Audits
(Greek Atomic Energy Commission)
Quality Control Quality Assurance
(QC-QA)
Internal Audits
Tools for Quality
EFOMP Symposium,Athens -12 Sept 2014, ΕΕΑΕ, [email protected]
Competent national regulatory authority in the fields of radiological protection and nuclear safety.
Greek Atomic Energy Commission (ΕΕΑΕ)
It is an independent public service, supervised by the General Secretariat for Research and Technology under the Ministry of Education & Religious Affairs.
Regulatory and legal duties Inspection duties Services (personnel dos., calibrations, environmental
controls, etc) Education and research duties Radiological emergency
Integrated Management System : ISO 9001 (TUV Hellas) Quality Management Systems : ISO 17020 and ISO 17025 (Hellenic Accreditation System - ESYD)
EFOMP Symposium,Athens -12 Sept 2014, ΕΕΑΕ, [email protected]
31 : Hospitals – Clinics (Aug 2014)
RT & BT in Greece
Total Public Private
≥ 3 systems (Linac or Co60) 4 2 2
2 systems (Linac or Co60) 13 9 4
1 Linac or Co60 9 8 1
Only BT (HDR or I125 seeds) 5 5
EFOMP Symposium,Athens -12 Sept 2014, ΕΕΑΕ, [email protected]
≈ 60 photon beams (6–23 MV) 7 60Co beams ≈ 130 electron beams (4-21 MeV)
IMRTat 5 RT centersfor ≈ 12 systems
4 linacs / 1 M population - 250,000 inhabitants / Linac
Tendency to growth : Replacement of old systems & new centers
RT & BT in Greece
EFOMP Symposium,Athens -12 Sept 2014, ΕΕΑΕ, [email protected]
EEAE inspections and dosimetry audits in RT and BT, in Greece
Scope :• Assessment of radiation protection of workers – patients – public• Assessment of safe performance of radiological equipment• Assessment of applied patient dosimetry• Assessment of applied clinical and dosimetry procedures and practices• Identification of errors and mal-practices / Investigation / Recommendations• Harmonization of dosimetry protocols at national level • Comparison of dosimetry results with other studies worldwide
EFOMP Symposium,Athens -12 Sept 2014, ΕΕΑΕ, [email protected]
Dosimetry Audits, ΕΕΑΕ
On site visits
• Ionization chambers - detectors• EEAE dosimetry & QC equipment
(independent from users’)• Calibration in IRCL/EEAE-EIM
SSDL • QC-QA and dosimetry protocols
(IAEA TRS 398) Applied to all RT & BT centers and systems
Rounds1st round : 2002 - 20062nd round : 2006 - 20113rd round : 2011 - ...
EFOMP Symposium,Athens -12 Sept 2014, ΕΕΑΕ, [email protected]
Dosimetry equipment
ABSOLUTE DOSIMETRY • Photons in water : Waterproof Farmer type 0.6 cc - IBA FC65 P IC-69 • Photons in Solid Water Phantom : Flexible IC 0.3 cc - PTW 31003• Electrons in water : Parallel plate - PTW MARCUS (since 2011)• Electrons in water : Parallel plate - PTW ADVANCE (after 2011)• Electrometer : PTW UNIDOS 10001
RELATIVE DOSIMETRY • IBA solid state / diodes for photons and electrons
Dosimetry Audits, EEAE
EFOMP Symposium,Athens -12 Sept 2014, ΕΕΑΕ, [email protected]
IBA RFA 200, 2D water phantomOmniPro-Accept software• Solid state diodes • Farmer IC• P-P electron IC
Solid Water Phantom• Insert for PTW flexible IC
Dosimetry Audits, EEAE
Basic Phantoms
EFOMP Symposium,Athens -12 Sept 2014, ΕΕΑΕ, [email protected]
Dosimetry Audits, EEAE
1. Assessment of Mechanical and Functional equipment performance2. Relative (PDD, profiles, etc) and Absolute dosimetry in water (Gy/MU)3. Assessment of TPS output4. Assessment of the overall radiotherapy procedure, for dosimetry
Dosimetry Audit performed in
4 levels[ performed in sequence : from basic to complex ]
EFOMP Symposium,Athens -12 Sept 2014, ΕΕΑΕ, [email protected]
Basic parameters : Field size Accuracy of gantry and collimator rotation Accuracy of table movement and rotation Stability of the isocentre (ISO) during rotations Laser accuracy
1. Assessment of Mechanical and Functional equipment performance
EFOMP Symposium,Athens -12 Sept 2014, ΕΕΑΕ, [email protected]
Deviations |δ| classified in three categories :
|δ| < 2 mm : Accepted2 < |δ| < 4 mm : Investigation|δ| > 4 mm : Non-accepted
1. Assessment of Mechanical and Functional equipment performance
EFOMP Symposium,Athens -12 Sept 2014, ΕΕΑΕ, [email protected]
0,0
10,0
20,0
30,0
40,0
50,0
60,0
70,0
80,0
90,0
100,0
LIGHT-FIELDDIMENSIONS
LIGHT-COLLIMATOR
LIGHT-IRRADIATION
CROSS-HAIRGANTRY
CROSS-HAIRTABLE
CROSS-HAIRCOLLIMATOR
MECHANICALISOCENTRE
LASERISOCENTRE
LINAC < 2mm
Co-60 <2 mm
LINAC 2mm<D<4mm
Co-60 2mm<D< 4mm
LINAC <4mm
Co-60 <4 mm
x
> 4 mm
> 4 mm
235 tests for Linacs & 81 for Co-60
1. Assessment of Mechanical and Functional equipment performance
EFOMP Symposium,Athens -12 Sept 2014, ΕΕΑΕ, [email protected]
2. Relative and Absolute dosimetry
EFOMP Symposium,Athens -12 Sept 2014, ΕΕΑΕ, [email protected]
EEAE measures in water phantom
• TPR20,10, for photons • R50 for electrons• percent depth dose, PDD • beam profiles
Dose at reference point, Dw
ΕΕΑΕ measurements, DM, are compared with the center’s stated values, DS
r = DS/DM relative deviation, dr = [(DS/DM ) – 1] ×100%
2. Relative and Absolute dosimetry
EFOMP Symposium,Athens -12 Sept 2014, ΕΕΑΕ, [email protected]
Uncertainties of EEAE measurements
Measurement of Dose to Water Type A Type B
% %Calibration coefficient, ND,w, of IC + electrometer 0.90Long term stability of ND,w 0.10 Scale reading / resolution 0.00Stability of measurements 0.10 Temperature & Pressure 0.17 0.08Temperature difference (thermometer & maes. point) 0.00Uniformity of radiation beam 0.06Depth - IC positioning 0.29Field size, SSD, angle 0.50Leakage current 0.00Recombination loss 0.10Polarity effct 0.10Beam quality correction, kQ 1.00
QUADRATIC SUM 0.22 1.47Combined Standard Uncertainty, k=1 1.49 %EXPANDED UNCERTAINTY, k=2 2.98 %
2. Relative and Absolute dosimetry
EFOMP Symposium,Athens -12 Sept 2014, ΕΕΑΕ, [email protected]
Comparison - Acceptance
d ≤ 3 % : Accepted3% < d < 5% : Investigation
d ≥ 5% : Non-accepted
1st round 2nd round 3rd round
│dr│≤ 3% 79.2% 96.9% 93.5%
3% <│dr│< 5% 16.7% 3.1% 6.5%
│dr│≥ 5% 3.1% 0.0% 0.0%
2. Absolute dosimetry at reference point (Gy/MU) : Photons
Standard uncertaintyof DM : ~ 1.5 %
EFOMP Symposium,Athens -12 Sept 2014, ΕΕΑΕ, [email protected]
2. Absolute dosimetry at reference point (Gy/MU) : Electrons
1st round 2nd round 3rd round
│dr│≤ 3% 82.1% 71.1% 95.7%3% <│dr│< 5% 5.0% 28.9% 4.3%
│dr│≥ 5% 12.9% 0.0% 0.0%
Standard uncertainty~ 2.0 %
EFOMP Symposium,Athens -12 Sept 2014, ΕΕΑΕ, [email protected]
2. Absolute dosimetry : BT
Reference Air Kerma Rate (Gy h-1 @ 1m)
Standard uncertainty~ 0.8 %
EFOMP Symposium,Athens -12 Sept 2014, ΕΕΑΕ, [email protected]
• Various clinical irradiation conditions are predefined in random, e.g. 18MV, field 12 x 7, depth 8.5 cm, SAD/SSD, Wedge 45o, etc. [Gantry=0o]
• TPS calculates the MU (or min), in order to deliver 1 Gy at the predefined depth and irradiation conditions
• The irradiation conditions are reproduced at Linac (or Cο60) in a water phantom & the irradiation performed for the calculated MU (or min)
• EEAE measures the Dw & deviations from 1 Gy are derived• Tests are performed for many & different irradiation conditions (> 15).
3. TPS output
EFOMP Symposium,Athens -12 Sept 2014, ΕΕΑΕ, [email protected]
data > 2011
3. TPS output
-10%-9%-8%-7%-6%-5%-4%-3%-2%-1%0%1%2%3%4%5%6%7%8%9%
10%Assesment of TPS output 6MV
18MV or 15MV
10MV
Dev
iati
on
, %
d ≤ 3 % : Accepted3% < d < 5% : Investigation
d ≥ 5% : Non-accepted
Standard uncertaintyof DM : ~ 1.5 %
EFOMP Symposium,Athens -12 Sept 2014, ΕΕΑΕ, [email protected]
data > 2011
3. TPS output
-10%-9%-8%-7%-6%-5%-4%-3%-2%-1%0%1%2%3%4%5%6%7%8%9%
10%Assesment of TPS output 6MV
18MV or 15MV
10MV
Dev
iati
on
, %
d ≤ 3 % : Accepted3% < d < 5% : Investigation
d ≥ 5% : Non-accepted
Standard uncertaintyof DM : ~ 1.5 %
“We do not complete th
e audit until w
e investigate &
resolve all deviations (d
> 3%)”
EFOMP Symposium,Athens -12 Sept 2014, ΕΕΑΕ, [email protected]
4. Assessment of overall RT procedure
Simulation of all RT steps, with a solid water phantom : CT scan
SimulationTreatment Planning
Positioning - VerificationIrradiation
Hospital’s procedures are followedAll steps are performed by the hospital’s staff
EFOMP Symposium,Athens -12 Sept 2014, ΕΕΑΕ, [email protected]
4. Assessment of overall RT procedure
Flexible IC
IC’s reference point is at the geometrical center of the phantom (cross marking).
EFOMP Symposium,Athens -12 Sept 2014, ΕΕΑΕ, [email protected]
Initial preparation
Marking, with bee-bees, a hypothetical original
(anatomical) isocentre (ISO)
EFOMP Symposium,Athens -12 Sept 2014, ΕΕΑΕ, [email protected]
Treatment Isocenter determination
Anatomical ISO defined by the bee-bees
Treatment ISO is determined from the respective CT slice& it corresponds to the
geometrical centre of phantom
EFOMP Symposium,Athens -12 Sept 2014, ΕΕΑΕ, [email protected]
Therapy simulation – Offset determination
Deviation of treatment isocentre from phantom geometrical centre
d ≤ 2 mm
Followed TPS data : Offset from
Original – Anatomical Isocentre toTreatment Isocentre (should be at the phantom center)
EFOMP Symposium,Athens -12 Sept 2014, ΕΕΑΕ, [email protected]
Treatment planning
CUBE : BOX technique (4 diametrically fields)OBLIQUE : 1 vertical (0o) with wedge and 2 lateral (sideways, e.g. 105o and 255o)
MU calculation, in order to deliver
total dose to treatment isocentre
(from all fields)2 Gy
EFOMP Symposium,Athens -12 Sept 2014, ΕΕΑΕ, [email protected]
Phantom irradiation
• Phantom positioning : Cards from TPS are followed• EEAE measures the dose from each field, DM,i and the total dose,
DM,T
• Comparison of DM,I and DM,T with the dose values as stated by the RT staff, according to TPS output data.
EFOMP Symposium,Athens -12 Sept 2014, ΕΕΑΕ, [email protected]
4. Assessment of overall RT procedure
d ≤ 5 % 5 % < d < 7 %
d ≥ 7 %-30%
-25%
-20%
-15%
-10%
-5%
0%
5%
10%
15%
20%
25%
30%Assesment of the overall RT procedure BOX-6MV
BOX-18MV
OBLIQUE-6MV
OBLIQUE-18MV
De
via
tio
n %
Standard uncertainty~ 3.0 %
data > 2011
EFOMP Symposium,Athens -12 Sept 2014, ΕΕΑΕ, [email protected]
4. Assessment of overall RT procedure
d ≤ 5 % 5 % < d < 7 %
d ≥ 7 %-30%
-25%
-20%
-15%
-10%
-5%
0%
5%
10%
15%
20%
25%
30%Assesment of the overall RT procedure BOX-6MV
BOX-18MV
OBLIQUE-6MV
OBLIQUE-18MV
De
via
tio
n %
Standard uncertainty~ 3.0 %
data > 2011
“We do not complete th
e audit until w
e investigate &
resolve all deviations (d
> 3%)”
EFOMP Symposium,Athens -12 Sept 2014, ΕΕΑΕ, [email protected]
CONCLUSION
• Patient Dosimetry and Radiation Protection is at high level in Greece.
• EEAE applies system inspections and dosimetry audits in RT and BT (and elsewhere) over 14 years, continuously and systematically. The experience gained is important.
• Benefits: Improved dosimetry - harmonization - dissemination of information - strengthening the confidence of hospitals’ staff.
• Hospitals welcome and seek inspections and audits of EEAE.
EFOMP Symposium,Athens -12 Sept 2014, ΕΕΑΕ, [email protected]
Challenges and Future work
• Small field dosimetry
• Dosimetry in “New technologies” (Tomotherapy, Cyber-Knife Gamma-Knife)
• Reporting of accidents
• Clinical Audit
• Enhancement of “Safety culture” and “Security culture”
• “Quantity” vs “Quality” to be balanced in a few cases
EFOMP Symposium,Athens -12 Sept 2014, ΕΕΑΕ, [email protected]
I thank you for your attention