522
J. Apostolakis
of components. Both have seen increasing use for research and in selected clinical
settings.
The therapy potential of light ion beams has been the topic of increasing
research during the past decade. A key drawback is the energy deposition of nuclear
fragments which extends beyond the Bragg peak. Early comparisons identified
discrepancies of some tens of percent in non-differential quantities between data
and MC [136].
In more recent studies better agreement in these tail dose depositions and dose
profiles was obtained with GEANT4 and FLUKA, but differences in prompt gamma
emission continue to be an issue [137]. The lateral beam widening is also well
confirmed by FLUKA results [138].
A key need in ion therapy is the monitoring of the range of ions. The detection
of positron emission in a PET detector has been in clinical use, and a newer method
involves prompt gamma emission. Both techniques have been investigated using
particle transport to quantify the location of emission and the spectra of clinically
interesting gammas.
Modeling of ion–ion interactions at therapeutic energies is frequently at the edge
of applicability for cascade models (below 150–200 MeV), and the resulting spectra
are influenced by the details of many nuclear de-excitation processes. Discrepancies
in secondary particle production in FLUKA were improved with the addition
of a Boltzman Master Equation (BME) model and other modelling refinements
[139]. New measurements have been made with ion projectiles to provide data
for comparison and improvement of modelling. One set using lower energy (62
A MeV) 12 C beam measured a large set of secondary spectra (p, d, t through to 11 B)
[140]. Comparison with GEANT4 models revealed the need for improvement of the
modeling used (binary cascade and QMD).
FLUKA’s existing applications in particle therapy [141] include the production
of data for Treatment Planning Systems (TPS), checking the plans created by TPS in
selected cases for quality control and improvement of patient dose delivery, and in
feasibility and sensitivity studies of prompt gammas for range and dose monitoring.
Another use has been the monitoring of dose delivery in ion therapy through PET
imaging of positron emitter production, undertaken either after treatment or through
an integrated PET device during the patient treatment.
11.6.3 Developments for Microdosimetry and Nanodosimetry
New models and adaptation of physics models have been developed to extend their
application to smaller energies. Dedicated Monte Carlo track structure codes have
been used in the investigation of radiation effects at the micron scale and at scales
appropriate for biological research [142] and modeling of radiotherapy outcomes
[143]. GEANT4 has been extended to provide track structure modeling in liquid and
gaseous water with the development of the GEANT4-DNA package [144]. This has
enabled its use in many applications in these fields [145, 146].
J. Apostolakis
of components. Both have seen increasing use for research and in selected clinical
settings.
The therapy potential of light ion beams has been the topic of increasing
research during the past decade. A key drawback is the energy deposition of nuclear
fragments which extends beyond the Bragg peak. Early comparisons identified
discrepancies of some tens of percent in non-differential quantities between data
and MC [136].
In more recent studies better agreement in these tail dose depositions and dose
profiles was obtained with GEANT4 and FLUKA, but differences in prompt gamma
emission continue to be an issue [137]. The lateral beam widening is also well
confirmed by FLUKA results [138].
A key need in ion therapy is the monitoring of the range of ions. The detection
of positron emission in a PET detector has been in clinical use, and a newer method
involves prompt gamma emission. Both techniques have been investigated using
particle transport to quantify the location of emission and the spectra of clinically
interesting gammas.
Modeling of ion–ion interactions at therapeutic energies is frequently at the edge
of applicability for cascade models (below 150–200 MeV), and the resulting spectra
are influenced by the details of many nuclear de-excitation processes. Discrepancies
in secondary particle production in FLUKA were improved with the addition
of a Boltzman Master Equation (BME) model and other modelling refinements
[139]. New measurements have been made with ion projectiles to provide data
for comparison and improvement of modelling. One set using lower energy (62
A MeV) 12 C beam measured a large set of secondary spectra (p, d, t through to 11 B)
[140]. Comparison with GEANT4 models revealed the need for improvement of the
modeling used (binary cascade and QMD).
FLUKA’s existing applications in particle therapy [141] include the production
of data for Treatment Planning Systems (TPS), checking the plans created by TPS in
selected cases for quality control and improvement of patient dose delivery, and in
feasibility and sensitivity studies of prompt gammas for range and dose monitoring.
Another use has been the monitoring of dose delivery in ion therapy through PET
imaging of positron emitter production, undertaken either after treatment or through
an integrated PET device during the patient treatment.
11.6.3 Developments for Microdosimetry and Nanodosimetry
New models and adaptation of physics models have been developed to extend their
application to smaller energies. Dedicated Monte Carlo track structure codes have
been used in the investigation of radiation effects at the micron scale and at scales
appropriate for biological research [142] and modeling of radiotherapy outcomes
[143]. GEANT4 has been extended to provide track structure modeling in liquid and
gaseous water with the development of the GEANT4-DNA package [144]. This has
enabled its use in many applications in these fields [145, 146].