11 Application of Accelerators and Storage Rings
719
7 MeV linac, was developed and built by a collaboration between Elekta, Philips,
and several clinics from Europe and North America [68]. The advantages of MRI
scanning are the capability of identifying movements of soft tissue and organs,
which are not detectable with other imaging media, and the absence of ionizing
radiation exposure. Today the average frame rate during dynamic acquisitions is of
the order of 10–20 frames per seconds with spatial resolution of the order of 2 mm.
The major companies producing electron linacs for photon therapy and the
characteristics of some of the most advanced models are listed in Table 11.5.
It must be mentioned that, because of the increase risk due to the non-negligible
production of photoneutrons, the use of the 16–20 MV photons is limited to the
cases for which the size of the patient and the depth of the tumour require it. In
normal conditions 6–8 MV energies are employed.
Neutron Therapy
At variance with the case of conventional radiotherapy, the use of atomic nuclei
to treat cancer has benefited of a long series of accelerator developments, which is
still continuing today. This is the reason for which we focus, in this second Part, on
hadron accelerators.
‘Hadron therapy’ (‘hadronthérapie’ in French, ‘hadronentherapie’ in German,
‘adroterapia’ in Italian, ‘hadroterapia’ in Spanish) is a collective word which covers
all forms of radiation therapy which use beams of particles made of quarks:
neutrons, protons, pions, and ions of helium, carbon, neon, silicon, and argon
have been used for treating cancer. Furthermore, lithium and boron ions, as well
as antiprotons have been investigated as potential candidates. ‘Hadron therapy’,
‘particle therapy’, ‘ion-beam therapy’, ‘heavy ion therapy’ and ‘light ion therapy’
are other terms often used to indicate the same procedure, and every performing
facility has its favorite term.
The first hadrons used for treatment purposes are the neutrons. The time
progression in implementing neutron therapy was so fast that is astonishing today.
The neutron was discovered by James Chadwick in 1932. Soon after, Ernest
Lawrence and his brother John were experimenting with the effects of fast neutrons
on biological systems. Following a paper by Gordon Locher [69], who in 1936
underlined the therapeutic potentialities of both, fast and slow neutrons, at the end
of September 1938, the first patient was treated at the Berkeley 37-in. cyclotron.
The first study on 24 patients, which used single fractions, was considered a success
and led to the construction of the dedicated 60-in. Crocker Medical Cyclotron. Here
Robert Stone and his collaborators (Fig. 11.24) treated patients with fractionated
doses using fast neutrons. The tuning of the dose to control the tumour and prevent,
at the same time, the complication of the normal tissue was still developing. The
dose given to healthy tissues was too high, so that in 1948 the program was
discontinued [70].
Neutron therapy was revived in 1965 by Mary Catterall at Hammersmith Hospital
in London and later various centres were built where fast neutrons were used for
many years. In particular in the 1970s radiation oncologists of Chicago worked with
Robert Rathbun (Bob) Wilson, Fermilab Director, to build the ‘Neutron Therapy
719
7 MeV linac, was developed and built by a collaboration between Elekta, Philips,
and several clinics from Europe and North America [68]. The advantages of MRI
scanning are the capability of identifying movements of soft tissue and organs,
which are not detectable with other imaging media, and the absence of ionizing
radiation exposure. Today the average frame rate during dynamic acquisitions is of
the order of 10–20 frames per seconds with spatial resolution of the order of 2 mm.
The major companies producing electron linacs for photon therapy and the
characteristics of some of the most advanced models are listed in Table 11.5.
It must be mentioned that, because of the increase risk due to the non-negligible
production of photoneutrons, the use of the 16–20 MV photons is limited to the
cases for which the size of the patient and the depth of the tumour require it. In
normal conditions 6–8 MV energies are employed.
Neutron Therapy
At variance with the case of conventional radiotherapy, the use of atomic nuclei
to treat cancer has benefited of a long series of accelerator developments, which is
still continuing today. This is the reason for which we focus, in this second Part, on
hadron accelerators.
‘Hadron therapy’ (‘hadronthérapie’ in French, ‘hadronentherapie’ in German,
‘adroterapia’ in Italian, ‘hadroterapia’ in Spanish) is a collective word which covers
all forms of radiation therapy which use beams of particles made of quarks:
neutrons, protons, pions, and ions of helium, carbon, neon, silicon, and argon
have been used for treating cancer. Furthermore, lithium and boron ions, as well
as antiprotons have been investigated as potential candidates. ‘Hadron therapy’,
‘particle therapy’, ‘ion-beam therapy’, ‘heavy ion therapy’ and ‘light ion therapy’
are other terms often used to indicate the same procedure, and every performing
facility has its favorite term.
The first hadrons used for treatment purposes are the neutrons. The time
progression in implementing neutron therapy was so fast that is astonishing today.
The neutron was discovered by James Chadwick in 1932. Soon after, Ernest
Lawrence and his brother John were experimenting with the effects of fast neutrons
on biological systems. Following a paper by Gordon Locher [69], who in 1936
underlined the therapeutic potentialities of both, fast and slow neutrons, at the end
of September 1938, the first patient was treated at the Berkeley 37-in. cyclotron.
The first study on 24 patients, which used single fractions, was considered a success
and led to the construction of the dedicated 60-in. Crocker Medical Cyclotron. Here
Robert Stone and his collaborators (Fig. 11.24) treated patients with fractionated
doses using fast neutrons. The tuning of the dose to control the tumour and prevent,
at the same time, the complication of the normal tissue was still developing. The
dose given to healthy tissues was too high, so that in 1948 the program was
discontinued [70].
Neutron therapy was revived in 1965 by Mary Catterall at Hammersmith Hospital
in London and later various centres were built where fast neutrons were used for
many years. In particular in the 1970s radiation oncologists of Chicago worked with
Robert Rathbun (Bob) Wilson, Fermilab Director, to build the ‘Neutron Therapy