Dose Course 2018_Flipping book
Point detectors for in vivo dosimetry
Before irradiation
Irradiation
readout heating
(G
)T
D dT
Conduction band Forbidden band Valence band
TLD
trap
trap
trap
Sensitivity: material;reader
light
h > 3,6eV
D I
T
N
P
N
P
Diode
Sensitivity: doping; pre-irradiation dose
MOSFET structure
I
(sat)= I
(dif)
I
(sat) + I
(ion) > I N
(dif)
n
N
n
n
I
= 0
total
MOSFET • Capable of dose measurements immediately after irradiation or can be sampled in predefined time intervals (on-line dosimetry) • Can operate in active (negative bias on gate during radiation) or M etal O xide S emiconductor F ield E ffect T ransistor •
V
D
Threshold
Sensitivity: thickness SiO2; bias during irradiation
passive mode
Soubra, Cygler, Mackay, Med. Phys. 21(4) , 567-572, 1994
Cygler, MOSFET dosimetry, AAPM Summer School 2009
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