Leksell Gama Knife

Corpo centrale contenente
201 sorgenti sigillate di
60Co
(A0 = 6000 Ci ± 10%)
Schermo piombato
da 185 mm
Leksell Gama Knife
Antonella del Vecchio
Lettino porta paziente che si
muove verso il centro della testata
ed inserisce il paziente nella zona
di trattamento.
Servizio di Fisica Sanitaria
IRCCS San Raffaele - Milano
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E’ possibile trattare volumi
anche se di forma irregolare
utilizzando isocentri multipli.
Dimensione e forma del
target possono essere variati
combinando
tra
loro
i
collimatori o chiudendone
una parte.
La peculiare struttura della
GK permette di strutturare
l’isodose
di
riferimento
(50%) esattamente attorno
al target con un coinvolgimento
Le sorgenti sono
distribuite
lungo
un’emisfera in modo
che la radiazione
converga verso un
punto
denominato
Unit Center Point
(isocentro RT)
Nello UCP viene
posizionato
il
bersaglio durante il
trattamento.
estremamente
limitato
strutture sane circostanti.
4 – 8 - 14 - 18 mm
A. del Vecchio
A. del Vecchio
delle
Mettere snapshot
1.
un casco che viene fissato
alla teca cranica del
paziente per mezzo di
quattro viti
1
2. una sfera di materiale plastico
che viene fissata al casco
e permette di misurare
l’encefalo
3.
un set di localizzaztori da
scegliere in base alla
metodologia diagnostica
prescelta (TC, RM, DSA)
2
Dopo aver eseguito
l’indagine
diagnostica, le
immagini vengono
inviate al
Gamma Plan
per l’elaborazione del
piano di
trattamento.
3
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A. del Vecchio
QA program
• Emergency tests (initialising, alarm, interlock) to check
safety and security of the machine for patients and workers
Ogni 6 mesi, controllo del sistema di trasferimento
ed elaborazione delle immagini con
ELEKTA MR PHANTOM
• Tests on acquisition and transfer of the CT and MR images
• Dosimetric tests (dose-rate, dose profiles, dose-response
linearity, output factors)
• mechanical and geometrical tests (timer accuracy, precision
of beam alignment, focus precision check, accuracy of
geometrical center and irradiation center)
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To check the correct
working of
collimators we
simulated a treatment
setting all different
collimators. We then
irradiated a head
phantom with gaf
chromic films inside
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Parameter
Tolerance
dose rate
± 2%
monthly
DD < ± 2%
Dd in progress
monthly
complex treatment reproducibility
timer accuracy
Frequency
< 0.07 min
monthly
distorsion and resolution
1 mm axial
2 mm coronal
two-yearly
output factors
± 3 % (16 mm),
± 3 % (8 mm),
± 5 % (4 mm)
two-yearly
+ 0.5 mm
two-yearly
± 1 mm
yearly
± 2%
yearly
accuracy
center
of geometrical and irradiation
dose profiles of all collimators on x, y, z
axis
dose-response linearity
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2D dose distribution from a gaf chromic for
the 16 mm collimator in xy plane and the
correspondent profile
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•
•
•
•
The stray radiation field inside the radiation unit of Leksell
GammaKnife® Perfexion™ has been measured using a custom made
holder (Fig. 1) for Thermo Luminescent Dosimeters.
257 TLD (type GR200A, LiF: Mg,Cu, chip Ø 4,5 x 0.8 mm, Sensitivity
0,5 µGy - 12 Gy, Reader type RADOS RE-2000)
were placed on a holder made of paper and Styrofoam with an
estimated resolution accuracy of 5 mm; every single TLD-chip was
placed in a special box to obtain the build-up condition.
Calibration of the TLD-chips were performed at CESNEF centre of
Politecnico University – Milan (Italy), using an ICRU-ISO Slab
300X300X150 phantom, with an ISO Co-60 beam. In this way the
measured values correspond to Hp(10).
4,5 5,1 6,4 4,6 4,5
4,4 5,9 5,5 5,8 5,7 6,1 5,1
4,7 5,4 5,4 5,3 4,9
5,6 5,5
6,7 5,6 5,3 10 5,7 5,6 6,8
5,6 5,7
5,1 5,2 5,6 5,9 5,0
5,2 6,0 5,8 5,6 5,4 6,1 4,9
4,7 4,5 6,0 5,2 5,1
OFF POSITION : -10 cm (mGy/h)
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40,6 48,1 41,4
37,5
59,0
42,5
57,9 57,9
47,9 56,7 64,1 55,8 42,9
56,4 54,1
41,4
55,8
41,2
39,7 43,8 41,6
OFF POSITION : 20 cm (mGy/h)
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Home Position - z axis
111,7
(mGy/h)
Stray field is “flowing” through the collimators in the direction
95,0
76,6
53,6
of the focus point. The magnitude of the field – measured as
Home Position - Central slide
35,7
-10
-5
120,0
(mGy/h)
16,3
11,2
-15
0
5
10
top ->
15
20
(cm)
25
100,0
x axis
80,0
y axis
Hp(10) - is approximately 2 mGy/min when the sectors are
60,0
x
40,0
either in sector Off or sector Home position. The field is
20,0
0,0
-25
-20
-15
-10
-5
0
5
10
15
20
slightly higher when the sectors are in Home position due to
25
(cm)
the fact that the treatment cavity is less effectively shielded
Off Position - z axis
from the sources at the very back on the sectors when the
(mGy/h)
96,0
sectors are in the Home position. The magnitude of this stray
64,1
Off Position - Central slide
15,0
10,0
-15
-10
-5
21,9
14,3
0
5
30,9
10
15
20
(cm)
field, and the assumption that this field has a relatively low
120,0
(mGy/h)
25
100,0
x axis
80,0
y axis
energy, indicates that this field has no, or at least a very low,
60,0
x
40,0
clinical significance.
20,0
0,0
-25
-20
-15
-10
-5
0
5
10
15
20
25
(cm)
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hSR : Patologie trattate
Attività Gamma Knife hSR
(2001 – 2006)
(1993 – 2006)
40,0
34,6
35,0
3
516 526
500
424
261 241
300
200
25,0
10,0
289
285
100
7,0
5,0
A
V
M
88
2006
2005
2004
2003
2002
2001
2000
1999
1998
1997
1996
1995
0
1994
2
1
4,8
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3,1
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Dosi massime consigliate (Gy)
Nervo ottico e chiasma
dose media
dose massima dose minima
22
14
25
24
30
18
35
14
24
9
22
33
10
13
15
10
40
18
25
22
Nervi cranici oculomotori
Trigemino
Acustico
Coclea
Brain sterm
Ipofisi
Stalk
Cristallino
Area motoria
Cute
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6,7
6,4
0,6
Dosi per patologia (50%)
Adenoma NS
Adenoma S
MAV
Melanoma uveale
Meningioma
MET
Neurinoma acustico
Nev. Trigemino
5,3
0,2
5
1993
12,6
0,0
211
152
112
17,2
20,0
15,0
367 372
400
(%)
30,0
600
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8
6 Se precedente RT
10 Dmax tollerata
12 20-30% cecità post trattamento
15
12 Con 13-14 Gy, 1-3% complicanze
13 50% deterioramento
8 Ipoacusia
14-15 Per piccoli volumi o interfaccia
10 Per grandi volumi
15 Ipopituitarismo
8 Ipopituitarismo
1 Cataratta con D > 5 Gy
15
10 Alopecia
20 Necrosi
Radiochirurgia per
Adenomi NS
Surgery
Postoperative MRI
Residual
adenoma
55 pts
48 pts
Gamma
Knife
Follow-up
Regrowth?
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Residual adenoma
1 yr follow up
GKRS
group
No GKRS
group
Patients N°
48
55
males
24
34
females
24
21
Mean age
55±2 yrs
52±2 yrs
Mean follow-up
40.5±3.4
months
2.5±0.3
63.7±5.3
months
3.1±0.4
Volume cm3
No Radiosurgery
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Radiosurgery vs No Radiosurgery
DiseaseDisease-free survival (%)
100
80
60
40
Preop
Preop
20
0
Gamma
GammaKnife
Knife
Radiosurgery
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P < 0.01
Log-Rank test
44yrs
yrsfollow-up
follow-up
0
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Radiochirurgia per
MAV
Definizione (Steiner e Lindquist)
Una MAV è considerata completamente chiusa
(obliterazione completa), quando un’angiografia
effettuata entro 3 anni dal trattamento dimostra
la completa assenza di vasi patologici, la
scomparsa/normalizzazione del drenaggio venoso
della zona, la normalizzazione del circolo nei
tempi venosi e arteriosi.
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20
40
60
80
100
120
Months
Probabilità di danno 1
Modelli previsionali
1. K index
Pobl = 3.073 * (D min ) * (VMAV )1/3 − 3.385
1 ≤ 3 VOL ≤ 2
0% ≤ Pobl ≤ 80%
2. Karlsson-Lax
3. Schwartz
4. Flickinger
Karolinska
P ( D, v) = 1 − ∏[1 − exp(− N 0 exp(− Di / D0 ))]
Δvi
Pobl = 35.69 * ln( Dmin ) − 39.66
Pobl = 100 * (1 − 1.15 * e −0.11*Dmin / d )
Pobl = 100
Ok fino a 20 Gy in 20 cc
MAV divise in 3 classi
Dmin > 35Gy
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Probabilità di danno 2
Pittsburgh
• Localizzazione della MAV
• V che riceve D>12 Gy
• Età
Dose
Anni Pz
V(MAV)
Dmedia(20cc)
V(12 Gy)
Tipo MAV
(1=C;2=PS;3=PNS)
Pb% necrosi
Pb% obliterazione
Pb% sanguinamento
22,0
25
2,100
9,0
8,900
1
4,05
70,66
1,465
21,0
25
2,100
8,6
1
3,86
69,00
1,610
20,0
25
2,100
8,2
1
3,69
67,26
1,761
24,0
25
2,100
9,8
1
4,45
73,76
1,198
25,0
25
2,100
10,2
1
4,66
75,22
1,076
25
2,100
9,4
1
4,24
72,25
1,328
23,0
Attenzione: la dose media in 20 cc si calcola come dose media su una matrice centrata sulla MAV con griglia 0,9
Pb% necrosi
y = 1,4465e0,1144x
30
25
0,1113x
y = 0,9816e
Serie1
20
Nome paziente:
Serie2
15
Serie3
10
Espo. (Serie1)
Lineare (Serie2)
5
Espo. (Serie3)
0
-5
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ModelloA. Karlsson
del Vecchio - Lax
0
10
20
y = 0,3925x - 2,8327
30
Radiochirurgia per
Metastasi
Tipologia MET
Tipologia Metastasi
50,0
• Single session
(2001)
45,0
40,0
• Peripheral dose 20 - 25 Gy
35,0
30,0
25,0
20,0
15,0
10,0
5,0
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non
specificato
sconosciuto
utero
tiroide
osteosarcoma
pancreas
ovaio
mammella
melanoma
gastrointestinale
rinofaringe
rene
polmone
0,0
• Lesion Ø ≤ 3 cm (volume 15 cm3) or total
tumor volume in multiple Mets ≤ 20 cm3
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Cerebral metastases
1.
2.
3.
4.
5.
• Prognosi
• N° Metastasi
• Istologia
1. Single Met
2. Ø >3 cm
3. RPA 1o 2
1.
2.
3.
1-4 Met
RPA 1 o 2
Ø ≤ 3 cm
YES
CHIRURGIA
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NO
MRI gad+
Total body CT or CT/PET
Bone scan
Histology
KPS
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NO
1.
RPA 3
or
2. ≥ 5 Mets
Cerebral Metastases
Radiosurgery
Surgery+RS in cystic metastases
Radiosurgery
Volume 4.7 cc
6 mo
GK radiosurgery
10-month follow-up
Surgery
Volume 16 cc
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Survival
Risultati
Median survival 12,1 months (188pz)
%
51,6% pz alive at 12 months
100
Controllo locale ad 1 anno: 89%
30,2% pz alive at 24 months
80
60
40
Complicanze
20
Radionecrosi, edema 8,6 %*
0
0
5
10
15
20
25
30
Months from GKS
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35
40
45
*In 2 pz surgical removal of the necrotic lesion
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Local Recurrences of the
treated Metasteses
Location is not a limitation for radiosurgery
1-year local recurrence
Radiosurgery
11%
Surgery
46%
WBRT
80- 100%
Surgery
+ WBRT
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Follow up and salvage therapy
GK o WBRT ?
Mortality
Mortality
Radiosurgery
2-8%
WBRT
0%
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1-4 new mets
Primary controlled
KPS>70
Gamma Knife
0%
Surgery
Surgery +
WBRT
10%
+
Yes
MRI: every
3 months
New mets
?
Follow-up
Yes
>5 mets
Primary
non controlled
KPS<70
NO
2-8%
WBRT
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Salvage Therapy:
2nd Radiosurgery
2nd
radiosurgery
1st
radiosurgery
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51 Yrs m: NSCLC. RPA1 controlled primary
•
•
•
•
•
•
3/12/1999: GK 3 mets
19/6/2000: GK 2 mets
5/3/2001: GK 1 met
1/2/2003: GK 3 mets (1 recurrent)
23/10/2003: GK 2 mets
May 2004: 8 mets> WBTR
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Gamma Knife Radiosurgery:
brain stem lesion
Trattamenti frazionati
20 patients have been treated in 3 fractions between Jan 2006 and Dec 2007 spaced out 24
hours each In all cases the most critical situation was the irradiation of chiasm and/or
optical nerve. Three patients were previously treated with GK (2) or RT (1), so they
presented the additional problem of taking into account accumulated doses.
PATHOLOGY
1 GK
2 GK
9 mo
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NEUROMA
2
MENINGIOMA
14
GLIOMA
1
ENDOCRANIC RELAPSES (k rinopharinx)
3
43 mo
3 GK
2 mo
n PATIENTS
30 mo
WBRT
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Although the use of the linear quadratic model in stereotactic
radiosurgery has some limits, at present time, no patients have
presented secondary effects due to irradiation, even if delivered doses
are higher than our normal single fraction constraints. Our calculation
model overestimates the doses at OARs, as it doesn’t take into account
cellular repopulation during the interval time.
ORGANS
TUMOURS
a/b
ORGANS AT RISK
RATIOS
NEUROMA
2
RATIOS
OPTICAL PATH
a/b
a/b
2
number of
Prescribed
fractions
dose/fraction [Gy]
BED
EqD
Dsf
(2Gy)
TARGET
3.3
3
7
65.5
41
13.1
OPTICAL
2
3
8.2
125.5
63
14.9
2
3
6.8
89.8
45
12.4
3.3
3
7.9
80.4
50
14.7
3
3
11.3
161.6
97
20.6
NERVE
MENINGIOMA
3.3
BRAIN STEAM
OTHERS MALIGNANT
10
CHIASM
3.3
CHIASM
BRAIN STEM
2
SKULL
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clinical results after fractionated
gamma knife radiosurgery
• The median follow-up was 12 months. Visual
acuity improved in one patient (7.1%); one patient
had improved visual field (7.1%). No patient had
visual deterioration.
• Tumor volumetric reduction was observed in 5
patients (35.7%), whereas in 9 patients (64.3%) no
volumetric variation was recorded.
•
•
•
•
•
•
•
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Mean pre-treatment volume 4.23 cm3 (3.3 cm3/ 0.33-8.1)
Mean prescription dose/session
6.9 ± 0.1 Gy (7/ 6.5-7)
Mean total prescription dose
20.7 (19.5-21 Gy).
Mean follow-up (median/range) 18 months (19/7-71)
Post-treatment visual acuity outcome
Improved
2
Worsened
0
Stable
12
Local tumor control
Reduction
5
Progression
0
Stable
9
Cranial nerves function
Improved
1
Worsened
0
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Stable
13
•
•
•
•
•
•
Patrizia Signorotto
Giovanni Mauro Cattaneo
Lucia Perna
Paola Mangili
Piero Picozzi
Alberto Franzin
A. del Vecchio
La Radiochirurgia Stereotassica Mediante GK, ha dato nel tempo
risultati superiori alle aspettative, ma :
• Importante lavoro d’EQUIPE : Neurochirurgo – Neurologo –
Radioterapista – Fisico
• Importante parco macchine per diagnostica
• Controlli di qualità accurati e precisi
• Aperto lo studio delle dosi agli organi critici nei ritrattamenti e
nei frazionamenti
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