Abstract: | The progress that has been made in radiotherapy lately besides unquestionable advantages,
originated many new problems which can be known and even partially or completely solved by
means of experimental and computational methods used in nuclear physics. The purpose of this
book is a presentation of the contribution of nuclear physics in solving the problems of the contemporary
radiotherapy.
Reduction of the irradiated field in teleradiotherapy saves healthy tissues located close to tumours.
However, it needs a precise localization and immobilization of a patient and a control of
its position during an irradiation séance. Therefore the experimental methods of nuclear physics
were inculcated to the clinical practice. These methods are based on the use of the various type
detectors of ionizing radiation, making it possible to control correctness and repeatability of a course
of a irradiation process of a patient. One of the base methods to control a dose delivered to
patients is in vivo dosimetry described in the first chapter of this book.
The contemporary planning systems take very accurate 3-D images of a patient’s anatomy
and a localization of a tumour into account. However, they need many parameters and characteristics.
The knowledge of the therapeutic beam spectra is particularly significant. The accurate determination
of such spectrum is not easy because of high radiation intensity in the therapeutic
beam and a broad energy range of radiation. There are experimental methods to derive the spectra
of therapeutic beams. However, the computer calculations based on the Monte Carlo method are
a current standard. The methods of a obtention of the therapeutic beam energy spectra are described
in the second chapter of this book.
Undesirable consequence of an increase of radiation energy in radiotherapy is a neutron contamination
of the therapeutic X-ray and electron beams. This contamination causes an additional
total body neutron dose to patients. Moreover, nuclear reactions induced by the neutrons are the
main factor of radioactivity inside a radiotherapy facility. The methods of a determination of neutron
fluence and an identification of induced radioisotope and occurred nuclear reactions are discussed
in the third and fourth chapter.
The photon needle is a relatively new technology applied in a clinical practice since 1992.
First versions of this device were characterized by a significant decrease of their efficiency appearing
even during a radiotherapy treatment. This defect was eliminated. However, it is still a big
problem to get an uniform dose distribution in an irradiated area. In connection with this fact it is
important to perform measurement verifying the uniformity of a dose distribution for each photon
needle used in a clinical practice. Results of the measurements testing the Intrabeam system —
the photon needle by Photoelectron Corporation & Carl Zeiss Surgical were presented in the fifths
chapter. The proton radiotherapy of eye tumours is widely used among the hadrontherapy methods because
of a high level of curability. Such therapy requires a high precision of a tumour irradiation
and also an accurate determination of influence of the beam parameters as mean energy, an energy
and spatial spread of the proton beam on the dose distribution. The determination of dependence
between the proton beam parameters can be carried out with the use of computer
simulations based on the Monte Carlo method ensuring a good quality of the obtained results.
Investigations of the dependence between the parameters of a proton beam and the dose distribution,
performed by computer simulations basing on the GEANT4 code are presented in the sixth
chapter of the book. |