724
M. Dohlus et al.
been treated and it has been shown that many common tumours otherwise difficult
to cure (e.g. lung and liver) can be controlled [81, 82].
In 1987 in Europe an important initiative was launched to create a full-fledged
European light-ion therapy centre. The characteristics of the needed hadron beams
were defined in a series of expert meetings. EULIMA, the European Light Ion
Medical Accelerator project, financed by the European Commission, was led by
Pierre Mandrillon and involved many European laboratories and centres. The
European therapy synchrotron was never built but instead national-based projects in
Germany and Italy were pushed through giving to the radiation oncologists facilities
similar to the HIMAC at Chiba and the Hyogo Ion Beam Medical Center.
In 1993 Gerhard Kraft and colleagues obtained the approval for the construction
of a carbon ion facility at GSI (Darmstadt), later called the “pilot project”. Hadron
therapy started in 1997 and, at the time of the closure in 2009, 440 patients
[83] were treated with carbon-ion beams. The medical and technical competences
were both used to build the Heidelberg Ion-Beam Therapy Center (HIT), which
started operation in 2009 [84] and transferred to Siemens Medical, which built the
HIT treatment rooms. The main new features of the GSI pilot project where: (i)
the active ‘raster’ scanning system [85]; (ii) the sophisticated models and codes
that take into account the biological effects of each irradiated sub-volume in the
treatment planning system; (iii) the in-beam PET system which determined ‘on-line’
the location and shape of the irradiated volume by detecting the β + radioactivity
produced by the incident carbon ions, mainly 11 C and 15 O [86–88].
11.3.2.2 The Bases of Cancer Radiation Therapy
The absorbed dose due to a conventional beam of photons has a roughly exponential
absorption in matter after a slight initial increase. For instance, the highest dose for
beams having a maximum energy of 8 MeV, is reached at a depth of about 2–3 cm
of soft tissue and the dose is about one third of the maximum at a depth of 25 cm.
Because of this non-optimal dose distribution, the unavoidable dose given to the
healthy tissues represents the limiting factor to obtain the best local control of the
pathology in conventional radiation therapy. In this connection, it has to be remarked
that even a small increase of the maximum dose can be highly beneficial in terms of
tumour control.
The radiation is given to the patient balancing two opposing goals, deliver a
sufficient dose to control the tumour and spare the normal tissue from dose levels
that could cause complications. To increase the dose to the tumour and not to the
healthy surrounding organs it is essential to ‘conform’ the dose to the target. In order
to selectively irradiate deep-seated tumours with X-rays, radiation oncologists use
multiple beams from several directions (portals), usually pointing to the geometrical
centre of the target. This is achieved by using a mechanical structure containing
the linac which rotates around a horizontal axis passing through the isocentre
(‘isocentric gantry’). The already mentioned IMRT makes use of up to 6–12 X-
M. Dohlus et al.
been treated and it has been shown that many common tumours otherwise difficult
to cure (e.g. lung and liver) can be controlled [81, 82].
In 1987 in Europe an important initiative was launched to create a full-fledged
European light-ion therapy centre. The characteristics of the needed hadron beams
were defined in a series of expert meetings. EULIMA, the European Light Ion
Medical Accelerator project, financed by the European Commission, was led by
Pierre Mandrillon and involved many European laboratories and centres. The
European therapy synchrotron was never built but instead national-based projects in
Germany and Italy were pushed through giving to the radiation oncologists facilities
similar to the HIMAC at Chiba and the Hyogo Ion Beam Medical Center.
In 1993 Gerhard Kraft and colleagues obtained the approval for the construction
of a carbon ion facility at GSI (Darmstadt), later called the “pilot project”. Hadron
therapy started in 1997 and, at the time of the closure in 2009, 440 patients
[83] were treated with carbon-ion beams. The medical and technical competences
were both used to build the Heidelberg Ion-Beam Therapy Center (HIT), which
started operation in 2009 [84] and transferred to Siemens Medical, which built the
HIT treatment rooms. The main new features of the GSI pilot project where: (i)
the active ‘raster’ scanning system [85]; (ii) the sophisticated models and codes
that take into account the biological effects of each irradiated sub-volume in the
treatment planning system; (iii) the in-beam PET system which determined ‘on-line’
the location and shape of the irradiated volume by detecting the β + radioactivity
produced by the incident carbon ions, mainly 11 C and 15 O [86–88].
11.3.2.2 The Bases of Cancer Radiation Therapy
The absorbed dose due to a conventional beam of photons has a roughly exponential
absorption in matter after a slight initial increase. For instance, the highest dose for
beams having a maximum energy of 8 MeV, is reached at a depth of about 2–3 cm
of soft tissue and the dose is about one third of the maximum at a depth of 25 cm.
Because of this non-optimal dose distribution, the unavoidable dose given to the
healthy tissues represents the limiting factor to obtain the best local control of the
pathology in conventional radiation therapy. In this connection, it has to be remarked
that even a small increase of the maximum dose can be highly beneficial in terms of
tumour control.
The radiation is given to the patient balancing two opposing goals, deliver a
sufficient dose to control the tumour and spare the normal tissue from dose levels
that could cause complications. To increase the dose to the tumour and not to the
healthy surrounding organs it is essential to ‘conform’ the dose to the target. In order
to selectively irradiate deep-seated tumours with X-rays, radiation oncologists use
multiple beams from several directions (portals), usually pointing to the geometrical
centre of the target. This is achieved by using a mechanical structure containing
the linac which rotates around a horizontal axis passing through the isocentre
(‘isocentric gantry’). The already mentioned IMRT makes use of up to 6–12 X-