CÁC HỆ THỐNG
THIẾT BỊ & KỸ THUẬT GHI ĐO
TRONG Y HỌC HẠT NHÂN
Nguyễn Văn Hoà
NUCLEAR MEDICINE
Diagnosis and therapy with
unsealed sources
Clinical problem
Radiopharmaceutical
Instrumentation
(99Mo  99mTc ) GENERATOR
99mTc
Shield
eluted
99Mo
Column
Saline
RADIONUCLIDE THERAPY
IN CRH NUCLREAR MEDICINE
Range of  of maximum
Energy (Emax)
in soft tissue
Augers
Alphas
DÖÔÏC CHAÁT PHOÙNG XAÏ cho SPECT
TC99m Pertechnetate
Tc99m MIBI
Tc99m MIBI
Tc99m Phytate
Tc99m MDP
Tc99m DTPA
DMSA
Assay of Absolute Activity
• Two methods are used for the determination of
absolute activity from the counting rate:
calibration table and calibration (standard) source
• Long-lived radionuclides are used as calibration
(“mock”) source: 137Cs for 131I, 129I for 125I and
57Co for 99mTc.
• Sample’s absolute activity X is given by X =
κA(mock)[R(sample)/R(mock)], where A is mock
activity and κ the ratio of emission frequencies
Dose Calibrators
• Dose calibrators are gas filled ionising chambers.
The gas is air and sealed to avoid variations in
temperature and atmospheric pressure.
• Dose calibrators are used to assay large quantities of
activities where it is too large for NaI(Tl) detector
(generator, patient preparation, shipment etc).
• The activity is determined by measuring the total
amount of ionisations in the chamber with no inherent
ability of energy discrimination.
Dose Calibrator
Introduction
Pulse height analyzer
Pulse height (V)
UL
LL
Time
The pulse height analyzer allows only pulses of a certain height
(energy) to be counted.
counted
not counted
Pulse-height distribution
NaI(Tl)
Nuclear Medicine Counting
• Nuclear Medicine radionuclide decay
counting follows Poisson distribution.
• Nuclear Medicine question is that how good
is the result N from a single measurement?
• The assumption is that Nm so that there is
68.3% chance that m is within the range
NN. N is uncertainty in N.
• Percentage uncertainty is defined as V=
(N/N) x 100%.
Counting Systems
•
•
•
•
Semiconductor systems
Liquid Scintillation Detectors
Gas-filled detectors
In vivo counting systems
Coincident Summing
• Occurs when a radionuclide emits two or
more γ rays from single disintegration.
• Prominent in detector system with high
geometric efficiency, such as well counter.
• Summing also occurs between x and γ rays
as well as two 511 KeV annihilation
photons
Scalers and Timers
• A device that only counts pulses is
called a scaler
• An auxiliary device that controls the
scaler counting time is called timer.
Counting Rates
• If N counts are recorded during time t, then
the counting rate is R=N/t. The uncertainty in
counting rate is then given by
 R  (1 / t ) N 
N
t
2
 Rt
And the percentage uncertainty
VR=(R/R)100%=100%/Rt
Scintillation detector
Detector
Amplifier
Photocathode
cathodd
Dynodes
PHA
Anode
Scaler
Well Counter
Automatic Multiple-Sample
Systems
• Automatic multiple sample systems are
necessary for counting large number of
samples or repeated tests
• The main problem of the multiple
sample well counters is the background
shielding on top of the wells
• SCA, MCA and computers are all being
used for the interface with the detectors.
Multiple-Sample System
Multi-Sample Through-Hole
System
Automatic Multiple Sample Liquid
Scintillation Counters
• Automatic multiple sample liquid
scintillation counters are designed to
handle large amount samples or
repeated counting.
Multi-Sample Liquid Counter
Analog Ratemeters
• A analog ratemeter is used to determine the
average number of events occurring per unit
time. The average is determined continuously
rather than over discrete counting time
• Linear vs logarithmic ratemeters: V0=knQRp vs
V0=klog(nQRp) - wider range of counting rate
• Ratemeter responds to the rate change has a time
constant which can be adjusted (change the
capacitor)
NaI(Tl) Probe System
THYROID UPTAKE
MEASUREMENT
In Vivo Counting Systems
• In vivo refers to human or animals body
• Probe system is designed to detect
single organ or localised parts of the
body
• A typical probe system employs 5x5cm
NaI(Tl) cylinder crystal plus cylindrical
or conical shaped collimator (as well as
PM tube etc).
Surgical Gamma Ray Probes
Gamma Ray Probe System
In Vivo Counting Systems
• Whole body counting system is
designed to measure total radioactivity
of whole body (not local activity).
• Most whole body counters employ large
NaI(Tl) crystal (15-30cm diam x 5-10 cm
thick) in order to detect high energy
photons and small activities.
PIONEERS
B. Cassen
H.O. Anger
Gamma camera
Used to measure the spatial and temporal distribution of a
radiopharmaceutical
Gamma camera
(principle of operation)
Position X
Position Y
Energy Z
PM-tubes
Detector
Collimator
GAMMA CAMERA
Gamma camera
Data acquisition
Static
 Dynamic
 ECG-gated
 Wholebody scanning
 Tomography
 ECG-gated tomography
 Wholebody tomography

Camera based SPECT systems can be one of the
configurations below:
Distances vs Positions
Step-and-Shot Acquisition
Rotational SPECT Camera
GAMMA CAMERA
SPECT cameras are used to
determine the three-dimensional
distribution of the radiotracer
Acquisition Protocols
Various different acquisitions can be performed
with a SPECT camera….
1.
2.
3.
4.
Planar Imaging
Planar Dynamic Imaging
SPECT Imaging
Gated SPECT Imaging
Cinematic Display
• Dynamic sequence
of images may be
displayed as a
continuous- loop
movie known as
cinematic display.
KIDNEY FUNCTION (Tc99mDTPA)
It is ideal to mark the background region in such a manner as to exclude
the arteries and calycial region.
Renogram
Ejection Fraction
Calculation
Segmental Wall Motion
Calculation
THYROID SCAN
BONE SCAN
Single probe
Scanner
Gammacamera
Whole Body Imaging Different Intensity
BONE SCAN
normal
pathologic
CEREBRAL BLOODFLOW
normal
Alzheimers disease
First Pass Cardiac Studies
• Data acquisition technique
– List or Frame: 0.5 second per image
• Data reformat
• Ventricular function evaluation
– EF, Ventricle size, wall motion similar to multiple gated
studies
• Detection of Intra-cardiac shunts
– Left to right shunt: Qs=Qp-Qsh; (Qp/Qs)>1.3
– Right to left shunt: some activity goes directly into the left
ventricle without first passing through the lung.
Gated SPECT
Phase Image
SHUNT QUANTIFICATION
ECG-GATED BLOODPOOL
SCANNING
MYOCARDIAL PERFUSION
TOMOGRAPHIC SLICES
coronal
sagittal
transversal
MYOCARDIAL PERFUSION
Stress
Rest
MYOCARDIAL PERFUSION
Cinematic Display
• The images to be
displayed are
formatted into an
area memory known
as buffer so that
information can be
retrieved quickly.
ECG-GATED MYOCARDIAL
PERFUSION
SPECT/CT
TECHNOLOGY & FACILITY
DESIGN
SPECT / CT
Scintillators
Density Z
(g/cc)
•
Na(Tl)I 3.67
51
Decay
time
(ns)
230
Light
yield
(% NaI)
100
Atten.
length
(mm)
30
BGO
7.13
75
300
15
11
LSO
7.4
66
47
75
12
GSO
6.7
59
43
22
15
Na(Tl) I works well at 140 keV, and is the most
common scintillator used in SPECT cameras
SPECT / CT
SUMMARY OF SPET/CT
• SPECT cameras are scintillation cameras, also called
gamma cameras, which image one gamma ray at a time,
with optimum detection at 140 KeV, ideal for gamma rays
emitted by Tc-99m
• SPECT cameras rotate about the patient in order to
determine the three-dimensional distribution of radiotracer
in the patient
• SPECT/CT scanners have a CT scanner immediately
adjacent to the SPECT camera, enabling accurate
registration of the SPECT scan with the CT scan, enabling
attenuation correction of the SPECT scan by the CT scan
and anatomical localization of areas of unusually high
activity revealed by the SPECT scan
PET
Positron Emission Tomography
Overall data flow during PET
acquisition and processing
Acquisition
Calibration data
Sinogram
Correction data
Counts/ray
Reconstruction
Image
ANNIHILATION
511 keV
positron
+
+
511 keV
CYCLOTRONS IN HOSPITALS
FDG Module
Target
Beam extractor
Ion
Source
Magnetic coil
Dees
PET Radiopharmaceuticals
Nuclide
Half-life
Tracer
Application
O-15
2 mins
Water
Cerebral blood flow
C-11
20 mins
Methionine
Tumour protein synthesis
N-13
10 mins
Ammonia
Myocardial blood flow
F-18
110 mins FDG
Glucose metabolism
Ga-68
68 min
DOTANOC
Neuroendocrine imaging
Rb-82
72 secs
Rb-82
Myocardial perfusion
F18-FDG
Manufacture of FDG
• End of bombardment of the target material with the
ion source beam is only 18F, NOT FDG
• Bombardment could typically be 2 hours (one halflife)
• 18F then sent to a chemistry module (synthesis
module) to react with a number of reagents to
produce fluorinated deoxyglucose
• Synthesis module performs a number of steps
such as heating, cooling, filtering, purifying, etc.
• FDG synthesis typically adds another hour
Manufacture of 18F
•
•
•
•
Proton is accelerated
Strikes 18O target
Merges with 18O
Neutron ejected
O + p F+ n
18
8
1
1
18
9
1
1
FDG
CH2HO
O
HO
OH
HO
OH
glucose
CH2HO
O
HO
HO
OH
18F
2-deoxy-2-(F-18) fluro-D-glucose
• Most widely used PET
tracer
• Glucose utilization
• Taken up avidly by
most tumours
18
9
F O +  + 
18
8
0
1
+
• E = mc²
• = 9.11 x10-31kg x (3x108)² m/sec
• = 8.2 x10-14 J
• = 8.2 x10-14 J ÷ (1.6x10-19 J/eV)
• = 511 keV
Coincidence Detection
Detector
Detector
PET
• Positron Emission
Tomography
• Functional information
• Tracers produced in
cyclotron
• Biological tracers
• ‘Hot spot’ on image
• Few anatomical
landmarks
CT
• Anatomical detail
• Cannot differentiate
between active and
benign disease
• Better resolution than
PET
• Good dynamic range
bone to lung
PET/CT
CYCLOTRON
PET/CT
• Combines the
functional information
with the anatomical
detail
• Accurate anatomical
registration
• Higher diagnostic
accuracy than PET or
CT alone
MULTIMODALITY IMAGING
PET
CT
Scan Process
1) CT scout view performed first
2) Full CT performed second
3) Patient moved into scanner and PET scan
acquired third
biograph LSO standard protocol Fused
PET/CT
FORE
AWOSEM
CT
PET
Upper limit
Lower limit
Topogram
attenuation correction
scatter correction
CT acquisition
XAÏ TRÒ NGOAØI : MAÙY GIA TOÁC (LINAC )
Treatment plan
RT planning and response
Case: Female with bronchial CA for RTP.
pre-treatment
Scan protocol:
Standard whole-body PET/CT scan pre- and posttherapy. Pre- and post-therapy PET/CT can be
registered using manualsyngo-fusion tool.
Findings:
Evaluate extent of disease prior to RT. RT planning
based CT or PET/CT. Evaluate RT response.
Data Courtesy ofUniversity Essen (Dr s S Marnitz and S Mueller)
post-treatment
CT
PET
CAÁP LIEÀU 188Re-HDD-Lipiodol Kieåm tra
baèng DSA
Heart
98
6
ABDOMINAL
AORTA
1
Aorta
Splee
n
Tieâm Re188
Lieàu Re-188
thaùm saùt (5mCi)
Lieàu Re-188
Tieâm lieàu 188Re-HDD-Lipiodol thaùm saùt
5mCi duøng DSA höôùng daãn
Maùy DSA
Heart
98
6
1
Aorta
ABDOMINAL AORTA
Splee
n
Tieâm lieàu Re188
thaùm saùt (5mCi)
THUAÄT TOAÙN TÍNH LIEÀU MIRD
MIRD
phantom
Coâng thöùc tính lieàu cô baûn :
D(rk) =
=
~
Ah Si D i f i (rk rh)
Mk
~
Ah S (rk rh)
Giaû ñònh :



Hình hoïc cô quan ngöôøi chuaån , tröø khoái U.
Cô quan nguoàn phaân boá hoaït ñoä ñoàng nhaát.
Cô quan bia haáp thuï naêng löôïng ñoàng nhaát.
B.2. THUAÄT TOAÙN TÍNH LIEÀU MIRD
Lieàu haáp thuï taïi cô quan bia :
MIRD
phantom
D(rk) =
=
~
Ah Si D i f i (rk rh)
Mk
~
Ah S (rk rh)
Beänh nhaân
Ngöôøi chuaån
SGiaû
(rkñònh
 rh)  S (rk rh)
Hình hoïc cô quan ngöôøi chuaån ,
tröø khoái U.
Cô quan nguoàn phaân boá hoaït ñoä
A.3. NGUOÀN XAÏ Re-188
Naêng löôïng :
β-(max) : 2.12 MeV
γ
: 155 KeV(15%)
Khoaûng chaïy trung bình cuûa β : 3.8 - 11 mm
Kieåu phaân raõ : β- to 188Osmium
Thôøi gian baùn huûy : 17.005 giôø
Nhaân meï :
188Tungsten
B.6. QUI TRÌNH LAÄP KEÁ HOAÏCH &
TÍNH LIEÀU DUNG NAÏP CÖÏC ÑAÏI Re-188
1. CT / MRI chaån ñoaùn, tính theå tích Gan, U gan.
2. LABO pha cheá Re-188 -HDD-Lipiodol vaø ño chuaån lieàu.
3. SPECT chuïp aûnh tính heä soá chuaån, suy giaûm,taùn xaï.
4. DSA höôùng daãn caáp lieàu Re-188 thaùm saùt .
5. SPECT chuïp aûnh phaân boá Re-188 thaùm saùt .
6. MIRD tính phaân boá lieàu haáp thuï trong cô theå.
7. Excel spreadsheet tính lieàu xaï trò dung naïp cöïc ñaïi ñeå lieàu
Gan laønh < 30Gy , phoåi < 12 Gy, tuûy xöông <1.5Gy.
8. DSA höôùng daãn caáp lieàu Re-188 xaï trò .
B.5. LAÄP KEÁ HOAÏCH & TÍNH LIEÀU DUNG NAÏP CÖÏC ÑAÏI Re-188
THEO THUAÄT TOAÙN MIRD
TÍNH LIEÀU Re - 188 XAÏ TRÒ K GAN HCC
DOSIMETRY
TREATMENT DOSE
EXCEL SPREAD SHEET
PHARMACEUTICAL
PATIENT DATA
CT / MRI
DSA
SPECT
DOSE CALCULATION
STANDARD
ANATOMY
DIAGNOSIS
SCOUT
STANDARD
ALGORITHM
( MIRD )
FLOOD
MASSES
VOLUME
TREATMENT
FLOOD
EXCEL
SPREAD SHEET
SCOUT
WEIGHT
FOLLOW UP
FPLLOW UP
SCOUT
DATA INPUT
FOLLOW UP
TREATMENT DOSE
OUTPUT
TREATMENT
TÍNH LIEÀU HAÁP THUÏ TAÏI BIA
Thuaät toaùn tính lieàu MIRD coù hieäu chænh
D(Gan laønh )
= D(Gan laønh  Gan laønh vôùi U )
D(Gan  Phoåi ) *
D(Gan  Tuûy xöông ) *
D(Gan  Phaàn coøn laïi cuûa cô theå ) *
+
+
+
D(Lung)
= D(Phoåi  Gan laønh vôùi U ) *
D(Phoåi  Phoåi ) *
D(Phoåi  Tuûy xöông ) *
D(Phoåi  Phaàn coøn laïi cuûa cô theå ) *
+
+
+
D(Red Marrow)
= D(Tuûy xöông  Gan laønh vôùi U ) *
D(Tuûy xöông  Lung) *
D(Tuûy xöông  Tuûy xöông ) *
D(Tuûy xöông  Phaàn coøn laïi cuûa cô theå ) *
+
+
+
* Duøng caùc heä soá S ñieàu chænh theo khoái löôïng
XAÏ HÌNH SPECT
Aûnh
toaøn
thaân
Ghi hình
nguoàn chuaån
Ghi hình nguoàn Re-188 trong
Phantom phaúng truyeàn qua
beänh nhaân
Re-188
Detector
Nguoàn chuaån Re188
Detector
Beänh nhaân
Re-188
lieàu
thaùm
saùt 5 mCi
Aûnh Gan vôùi 99mTc-Phytate vaø aûnh U gan vôùi
ATTENUATION
Re-188 lieàu
thaùm saùt 5 mCi .
Aûnh
Aûnh
nguoàn
chuaån
nguoàn
chuaån
Re-188
Aûnh
Phantom nguoàn phaúng
Gan
Aûnh
u gan
Aûnh truyeàn
qua Phoåi ,Gan
C.6. TÍNH LIEÀU XAÏ TRÒ BAÈNG EXCEL SPREADSHEET
THEO THUAÄT TOAÙN MIRD