The observation with high-resolution Ge detectors of the 1229 and 2171 keV gamma-rays emitted after the
28Si(μ, ν)
28Al(1
+, 2202 keV) reaction allowed us to determine the nuclear-amplitude ratio
x ≡
...M(2)
M(−1)
characteristic of this muon-capture reaction. Using the nuclear-structure dependent evaluation of various correction terms (model of Ciechanowicz), our result
x = +0.254±0.034 provides for the
induced pseudoscalar coupling
g
p the ratio
g
p
g
a
(0.848m
μ
2) = 3.4 ± 1.0
, to be compared to the PCAC prediction of
g
p
g
a
= 7
. The model dependence of this apparent quenching remains to be assessed.
Proton Therapy treatments are affected by uncertainties on the penetration depth of the beam within the patient. For this reason, real-time range control is highly desirable to deliver safer ...treatments. Real-time range control can be performed by imaging prompt gammas emitted along the proton tracks in the patient. Our approach uses a knife-edge slit collimator to obtain a 1-dimensional projection of the beam path on a gamma camera. The energy spectrum of prompt gammas includes energy events up to 10 MeV and the event rate on a 500 cm 3 scintillator is tens of MHz. Standard SPECT and PET modules are not suitable for the purpose and a dedicated gamma camera was designed. The camera features a 3 cm thick LYSO crystal segmented in two rows of 20 slabs with a width of 4 mm and a height of 10 cm. The crystal is coupled to arrays of Silicon Photomultipliers, read out by dedicated electronics boards to perform both spectra acquisition at low rates and photon counting at high rates for profile reconstruction. The prototype was aimed at reaching clinical requirements. The camera was tested in the Proton Therapy Center in Prague using an anthropomorphic phantom on which realistic treatment plans were delivered in pencil beam scanning mode. For each layer of the treatment, acquired profiles corresponding to the single spots were compared to simulated profiles and the shift was retrieved. The study demonstrated that the system is actually suitable for patient treatment monitoring.
The characteristic dose profile of accelerated ions has opened up new horizons in the context of cancer treatment. However, particle range uncertainties strongly constrain the potentialities of ion ...beam therapy. In spite of worldwide efforts, a detector system for range and dose delivery assessment in real-time is not yet available for clinical routine.
Prompt secondary radiations such as gamma rays and protons can be used for ion-range monitoring during ion therapy either on an energy-slice basis or on a pencil-beam basis. We present a review of ...the ongoing activities in terms of detector developments, imaging, experimental and theoretical physics issues concerning the correlation between the physical dose and hadronic processes.
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