good practice of clinical dosimetry reportingsecure site · sop on blood dosimetry for the...
TRANSCRIPT
KLINIK UND POLIKLINIK FÜR NUKLEARMEDIZINDIREKTOR: PROF. DR. REINERS
Good practice of clinical dosimetry reporting
M. Lassmann, C. Chiesa, G. Flux, M. BardièsEANM Dosimetry Committee
EANM Dosimetry Committee
Established in 2002
8 EANM Members from 7 European Countries
1 IAEA Observer
Chair: M Lassmann (2002-2008)
M Bardiès (from 2009)
Why do we need to talk about a guidance document on“Good Practice of Clinical Dosimetry Reporting”
Publication X:“We performed dosimetry according to the MIRD formalism”
Publication Y:“Dosimetry was performed using ROI’s on planar images and OLINDA”
Good Practice of Clinical Dosimetry Reporting
Published 2010Available on-line @:www.eanm.org/scientific_info/guidelines/guidelines_intro.php?navId=54
Purpose of the Document:Recommendations to scientists and clinicians on how to document and report diagnostic, pre-therapeutic and/or peri- therapeutic clinical absorbed dose assessments.
This includes a checklist on the respective methodologies used for obtaining quantitative data, for generating and integrating activity-time-curves and for calculating absorbed doses.
Not in the scope of the document:Recommendations for optimal dosimetric methods
Good Practice of Clinical Dosimetry Reporting
- Measurement of the activity retention in the target volume- Calculation of the area under the curve (AUC) representing the total number
of decays- Multiplication of the AUC with the ‘relevant’ (patient-specific) absorbed dose
per nuclear transformation (S) value for obtaining the absorbed dose
„Simple“ Dosimetry
Pre-Treatment Uptake
0
1
2
3
4
5
6
0 24 48 72 96 120 144 168 192time p.a. (h)
Upt
ake
U (%
)
time-integrated activity coefficient
Good Practice of Clinical Dosimetry Reporting
• Equipment• Image Quantification• Biokinetics• Dosimetry Calculations• Miscellaneous
Equipment
• General remarks• Probe Measurements• Well Counters Measurements• Dose Calibrators• Gamma-cameras• Quality Control
Appendix: Documentation Checklist
Probe Measurements
Is the probe used as a simple counter?In conjunction with gamma spectroscopy?Is the probe shielded and/or collimated?Are the geometric properties of the shielding/collimation given?Is the geometry of the patient measurement given?Are the background counts without any sources present given?Are the sensitivity and the window settings documented?Is the sensitivity range of the device provided?Are the dead time characteristics of the system known?
Dosimetry in Multi-Center Trials
Probe Measurements
Vertical Positioning(Spacer bar would be removed
for measurement)
Phantom Position Relative to Probe
Appendix: Documentation Checklist
Gamma-Cameras
Gamma camera make (name of the manufacturer) and model Crystal thicknessEnergy window(s) (number + range of each)Pixel size / Matrix sizeNumber of heads used for the acquisitionSoftware versionCollimatorStopping conditions
Image Quantification
• Acquisition settings• Phantom and Calibration Measurements• Sequential Imaging• Conjugate View Method• Processing Parameters (SPECT)• Background correction• Attenuation Correction• Scatter Correction• Partial Volume Effect Correction• Dead Time Correction• PET – Correction for “dirty” Nuclides
Appendix: Documentation Checklist
Gamma-Cameras•Stopping conditions•ROI location and size•Corrections for overlapping organs•Background correction•Method of attenuation / scatter correction•Dead time correctionSPECT•Number of projections•Orbit type•Rotation parameters•Reconstruction parameters•Software used
ROI´s for Remnants
Anterior Posterior
R7: S1(ROI ∅ 5 cm, 2“)
R8: S2
R9: “inner” remnant ROIR10: “outer” remnant ROI
Posterior
Anterior
Table
Neck Cushion
CardboardBox orStyrofoam
S2 S15 cm2”
20 cm, 8”
S1
S2
View from Left Side Top View
Local data extraction and calculations
Hänscheid et al.JNM 2006
Planar Scans – Monte-Carlo-Simulation
I-131, Monte-Carlo- Simulation
Ljungberg 98
Pre-Treatment Uptake
0
1
2
3
4
5
6
0 24 48 72 96 120 144 168 192time p.a. (h)
Upt
ake
U (%
)
- Measurement of the retention in the target volume
„Simple“ Dosimetry
Biokinetics
• Number of Data Points• Fitting and integration procedures• Extrapolation• Residence times
• Compartment modelling• Direct Integration using
Trapezoidals• Least-square fit
(linear combination of exponentials)
Important: Document all assumptions and methods (include, if possible, an error assessment)
Major sources of uncertainties are−
How is the AUC taken from 0 to the first data point
−
What are the assumptions after the last measurement (physical decay?)
Calculation of the AUC
- Measurement of the retention in the target volume- Calculation of the area under the curve (AUC) representing the total number
of decays- Multiplication of the AUC with the ‘relevant’ (patient-specific) absorbed dose
per nuclear transformation (S) value for obtaining the absorbed dose
„Simple“ Dosimetry
Pre-Treatment Uptake
0
1
2
3
4
5
6
0 24 48 72 96 120 144 168 192time p.a. (h)
Upt
ake
U (%
)
time-integrated activity coefficient
Dosimetry Calculations
• Calculation Procedure• S-Values• Mass (or volume) determination• Tumour dosimetry• Absorbed Doses (Results)• Statistical Errors• Radiobiological parameters
S-Values: Tabelle OLINDA
Blood absorbed dose calculation for thyroid cancer patients
Absorbed Dose: 0.24 Gy
wt = 78kg
0.01
0.1
1
10
100
0 20 40 60 80 100
Hours after Administration
Rel
ativ
e A
ctiv
ity in
Blo
od [%
/L]
Rel
ativ
e W
hole
Bod
y A
ctiv
ity [%
]
WB
Blood
2.46% / 2^(t/7.5h) + 0.927% / 2^(t/15.7h)
95.8% / 2^(t/9.4h) + 20.0% / 2^(t/18.6h)
τtotalbody = 16.1 [h]
τl of blood = 0.44 [h]
Therapy 3.7 GBqI-131
EANM Dosimetry Committee 2008 SOP on Blood Dosimetry for the Treatment of Thyroid Cancer
Miscellaneous
• Confounding factors• External Audit• Choice of Nuclide and Radiopharmaceutical• Units
Dosimetry - Units ?
The EANM Guidance Document helps to improv e reproducibility of dosimetric procedures by showing how to report all the steps needed for dosimetry:
• Choice and QC of the Equipment• Image and Data Quantification• Determination of Biokinetics and the Corresponding
Integration of the Time-Activity Curve • Dosimetry Calculations• Miscellaneous
Conclusions
KLINIK UND POLIKLINIK FÜR NUKLEARMEDIZINDIREKTOR: PROF. DR. REINERS
Good practice of clinical dosimetry reporting
M. Lassmann, C. Chiesa, G. Flux, M. BardièsEANM Dosimetry Committee