Upload
others
View
5
Download
0
Embed Size (px)
Citation preview
Towards patient‐specific dosimetry in nuclear medicine associating Monte‐Carlo and 3D voxel‐based approaches
L.Hadid, N. Grandgirard, N. Pierrat, H. Schlattl, M. Zankl, A.Desbrée
IRSN, French Institute for radiation protection and nuclear safety, Fontenay-aux-roses, FranceInstitut Curie, Paris, France
Helmholtz Zentrum München-German Center for Environmental Health, Neuherberg, Germany
International Symposium on Standards, Applications and Quality Assurance in Medical Radiation Dosimetry
IAEA, 9-12 November 2010, Vienna
2IAEA International Symposium, 9‐12 November 2010, Vienna
Context Results ‐
SAF
MIRD Formalism
Biokinetic aspect Geometric
aspect
Radiation Protection : Accurate and realistic dosimetry
EE
TT
/E/E
SS
MMT
SAF(rSAF(r
T T
rr
SS
) = ) =
)(~
STS
ST rrir i
irr SAFEnAD←∑ ∑= x
Results ‐
Patient‐based doses Results –
Reference doses
Tabulated reference data
Mathematical phantom
SAFs tabulated for mathematical standard geometries
3
sourcemassSCSAF 1)( =←
Target region = Source region
Target region ≠
Source region
0)( =← SCSAF
Walled source regions
sourcemassSCSAF
*21)( =←
Approximations applied
for electron SAFs
S
SC
S=C
C
IAEA International Symposium, 9‐12 November 2010, Vienna
Context Results ‐
SAF Results ‐
Patient‐based doses Results –
Reference doses
4
Monte Carlo calculations
OptimisationNew adult reference computational
phantoms of the ICRP
Male phantom Female phantom
Publication 110
of the ICRP
SAFsPhotons + Electrons(10 keV<E<10MeV)
HMGU(EGSnrc)
IRSN(MCNPX
+OEDIPE)
Absorbed dosesfrom radiopharmaceuticals
Standard
biokinetic of
11 radiopharmaceuticalsused in nuclear medicine
IAEA International Symposium, 9‐12 November 2010, Vienna
Context Results ‐
SAF Results ‐
Patient‐based doses Results –
Reference doses
Reference phantoms Fixed geometry
5IAEA International Symposium, 9‐12 November 2010, Vienna
Context Results ‐
SAF Results ‐
Patient‐based doses Results –
Reference doses
RESULTS
SAF Calculations
7
Comparison between voxelized and ORNL phantoms PHOTONS, SAF (Lungs <‐
Liver), Male
Low energiesRatio
Voxelized/ORNL 25
Different shapes and inter‐organ distances
High energiesRatio
Voxelized/ORNL 1,5
Small influence of the organ shapes on the
SAFs
Spe
cific
Abs
orbe
d Fr
actio
n (k
g-1)
Photon energy (MeV)
IAEA International Symposium, 9‐12 November 2010, Vienna
Context Results ‐
SAF Results ‐
Patient‐based doses Results –
Reference doses
ELECTRONS, SAF ( Lungs <- Lungs), Male
8
Ratio0,99< EGSnrc/MCNPX< 1,01
Low energies :SAF 1
High energies:Electron escapeS
peci
fic A
bsor
bed
Frac
tion
(kg-1
)
Electron energy (MeV)
Prior
approximations
LungsmLungsLungsSAF 1)( =←
kg 1mLungs=
IAEA International Symposium, 9‐12 November 2010, Vienna
Context Results ‐
SAF Results ‐
Patient‐based doses Results –
Reference doses
9
Application of the ICRP/ICRU reference computational phantoms to
internal dosimetry: calculation of specific absorbed fractions of energy for photons and electrons
L Hadid, A Desbrée, H Schlattl, D Franck, E Blanchardon and M Zankl
Phys.Med.Biol.55 (2010) 3631-3641
IAEA International Symposium, 9‐12 November 2010, Vienna
Cross-fire: for many organ pairs, voxel phantom SAFs higher than current values based on mathematical phantoms (inter-organ distances are larger in mathematical phantoms than in reality)
Photon SAFs
Electron SAFs
Cross-fire : SAFs can approach nearly the same order of magnitude as photon SAFs for higher electron energies and organs in close vicinity
Self-absorption : higher-energetic electrons escape, especially from small organs
Context Results ‐
SAF Results ‐
Patient‐based doses Results –
Reference doses
RESULTS
Dose CalculationsMathematical versus computational
reference phantoms
11IAEA International Symposium, 9‐12 November 2010, Vienna
Reference voxel phantoms
Standard biokinetic of
radiopharmaceuticals
(ICRP 53 + ICRP 80 + ICRP 106)
Absorbed doses for 11 radiopharmaceuticals used in nuclear medicine
Context Results ‐
SAF Results ‐
Patient‐based doses Results –
Reference doses
12
Absorbed doses for 18F-FDG
0,00
0,02
0,04
0,06
0,08
0,10
0,12
0,14
Adre
nals
Blad
der w
all
Bone
s sur
face
sBr
ain
Brea
st
Stom
ach
wall
Smal
l int
estin
eCo
lon
Gall
blad
der
Hear
tKi
dney
sLi
ver
Lung
sMus
cles
Oeso
phag
usOv
arie
sPa
ncre
asRe
d m
arro
w
Skin
Sple
enTe
stes
Thym
usTh
yroi
dUt
erus
Rem
aini
ng o
rgan
s
Effe
ctive
dos
eAbs
orbe
d do
se p
er u
nit
acti
vity
adm
inis
tere
d (m
Gy/
MBq
)
Reference mathematical phantom
Reference voxel male phantom
Reference voxel female phantom
IAEA International Symposium, 9‐12 November 2010, Vienna
Context Results ‐
SAF Results ‐
Patient‐based doses Results –
Reference doses
13IAEA International Symposium, 9‐12 November 2010, Vienna
Absorbed doses Mathematical versus voxel reference phantoms
Differences depend on target organ and radiopharmaceutical
131I - thyroid uptake 55 %
306 % (lungs) 272 % (lungs)
11C-Methionine
56 % (uterus) 59 % (Urinary bladder wall)
-Geometric: topology and distances between organs
- Physic: approximations previously used for electrons transport
Reasons
Context Results ‐
SAF Results ‐
Patient‐based doses Results –
Reference doses
RESULTS
Dose CalculationsMathematical phantoms using OLINDA/EXM
versus patient-based phantoms using OEDIPE
15IAEA International Symposium, 9‐12 November 2010, Vienna
Creation of the patient‐based voxel phantoms
Creation of a voxel phantom : ~ 8H
Specific voxel phantoms
Attribution
of the densities
TPS ISOGrayTM
Segmentation
of 27 organs
Voxelization
Context Results ‐
SAF Results ‐
Patient‐based doses Results –
Reference doses
16IAEA International Symposium, 9‐12 November 2010, Vienna
M1 M2 M3 M4 M5 M6
6 malephantoms
F1 F2 F3 F4 F5 F6
6 female
phantoms
Context Results ‐
SAF Results ‐
Patient‐based doses Results –
Reference doses
17
Absorbed doses for 18F-FDG for male phantoms
IAEA International Symposium, 9‐12 November 2010, Vienna
0,00E+00
2,00E‐02
4,00E‐02
6,00E‐02
8,00E‐02
1,00E‐01
1,20E‐01
1,40E‐01
Brain
Colon
wall
Gall b
ladde
r wall
Hear
t wall
Left
kidne
yRig
ht ki
dney
Liver
Left
lung
Right
lung
Panc
reas
Splee
nSt
omac
h wall
Testi
sTh
yroid
Urina
ry bla
dder
wall
Oeso
phag
us
Mean absorbed
dose pe
r un
ité activity adm
inistered (m
Gy.MBq
‐1)
M1M2M3M4M5M6Male reference mathematicalRCP‐AM
Context Results ‐
SAF Results ‐
Patient‐based doses Results –
Reference doses
18IAEA International Symposium, 9‐12 November 2010, Vienna
Determination of patient‐based doses : between 9H
and 16H
OEDIPE + MCNPX
Maximum dose differences between patient‐based phantoms and
Reference mathematical phantoms : ~ 400 %
(walled organs)174 %
(brain for 131I_55%)
Reference voxel phantoms : 113 %
(thyroid for 131I_55%)
Maximum absorbed dose differences among patients: factor 3,4
Context Results ‐
SAF Results ‐
Patient‐based doses Results –
Reference doses
19IAEA International Symposium, 9‐12 November 2010, Vienna
Context Results ‐
SAF Results ‐
Patient‐based doses Results –
Reference doses
+
Absorbed dose to target organs
or tumors
DVHIsodoses curves superimposed
on anatomical images
Thank you for your attention