720
M. Dohlus et al.
Fig. 11.24 Robert Stone is watched by John Lawrence while aligning a patient in the neutron
beam produced by the 60-in. cyclotron
Facility’ at Fermilab based on the injector linac [71]. At Michigan University, Henry
Blosser built for the Harper Hospital a proton cyclotron rotating around the patient.
The worldwide effort for high-current 40–60 MeV proton cyclotrons was large.
However, at present, this technique is rarely used. The reason is the poor depthdose distribution of fast neutron and the fact that, all along the path, the biological
effects, due mainly to highly ionizing protons put in motion by the neutrons, are
difficult to determine and tissue-dependent. As discussed in the following, carbon
ion beams are a much better solution to deliver doses being highly ionizing particles,
i.e. particles which have energy losses (Linear Energy Transfers—or LET—in the
medical parlance) much larger than the electrons put in motion by X rays.
Thermal and epithermal neutron are also used in Boron Neutron Capture Therapy
(BNCT). This cancer treatment is based in two subsequent procedures, first the
injection of the boron carrier, conceived to be absorbed preferably by the tumour,
and second the irradiation of the patient with low energy neutrons. Alpha particles
resulting from the reaction 10 B(n, 4 2 He) 7 Li release all their energy close to the point
where they are originated affecting the tumour cells.
Proton Therapy
The use of protons in teletherapy was proposed in 1946 by Bob Wilson [72], who
was asked by Lawrence to measure, at the Berkeley Cyclotron, proton depth-dose
profiles. Describing the significant increase in dose at the end of particle range,
the so-called Bragg peak, which had been observed 40 years before in the tracks
of alpha particles by W. Bragg, Wilson recognized in his paper the advantages in
treating tumours. The Bragg peak—which can be ‘spread’ with modulator wheels—
can be used to concentrate the dose sparing healthy tissues better than with X-rays.
It is interesting to remark that in his paper Wilson discussed mainly protons but
mentions also alpha particles and carbon ions.
M. Dohlus et al.
Fig. 11.24 Robert Stone is watched by John Lawrence while aligning a patient in the neutron
beam produced by the 60-in. cyclotron
Facility’ at Fermilab based on the injector linac [71]. At Michigan University, Henry
Blosser built for the Harper Hospital a proton cyclotron rotating around the patient.
The worldwide effort for high-current 40–60 MeV proton cyclotrons was large.
However, at present, this technique is rarely used. The reason is the poor depthdose distribution of fast neutron and the fact that, all along the path, the biological
effects, due mainly to highly ionizing protons put in motion by the neutrons, are
difficult to determine and tissue-dependent. As discussed in the following, carbon
ion beams are a much better solution to deliver doses being highly ionizing particles,
i.e. particles which have energy losses (Linear Energy Transfers—or LET—in the
medical parlance) much larger than the electrons put in motion by X rays.
Thermal and epithermal neutron are also used in Boron Neutron Capture Therapy
(BNCT). This cancer treatment is based in two subsequent procedures, first the
injection of the boron carrier, conceived to be absorbed preferably by the tumour,
and second the irradiation of the patient with low energy neutrons. Alpha particles
resulting from the reaction 10 B(n, 4 2 He) 7 Li release all their energy close to the point
where they are originated affecting the tumour cells.
Proton Therapy
The use of protons in teletherapy was proposed in 1946 by Bob Wilson [72], who
was asked by Lawrence to measure, at the Berkeley Cyclotron, proton depth-dose
profiles. Describing the significant increase in dose at the end of particle range,
the so-called Bragg peak, which had been observed 40 years before in the tracks
of alpha particles by W. Bragg, Wilson recognized in his paper the advantages in
treating tumours. The Bragg peak—which can be ‘spread’ with modulator wheels—
can be used to concentrate the dose sparing healthy tissues better than with X-rays.
It is interesting to remark that in his paper Wilson discussed mainly protons but
mentions also alpha particles and carbon ions.