Biomedical Engineering Reference
In-Depth Information
24.1.1
Historical development of Radiation Oncology
Shortly after Roentgen discovered x-rays in 1895 [
1
] and, three years later, Pierre
and Marie Curie discovered Radium [
2
], it was observed that certain properties of
ionizing radiations made them suitable for medical uses. Their ability to traverse
the soft tissues of an organism was the beginning of diagnostic imaging methods
and lead to a new specialty in medicine, Diagnostic Radiology. On the other hand,
in 1922 the field of Radiation Therapy was founded at the International Congress
of Oncology in Paris where evidence was presented showing that locally advanced
larynx cancer could be cured with radiation [
3
].
From that moment on, advances in our knowledge about radiobiology and
radiophysics and the technological development of equipment have allowed the
development of both Diagnostic Radiology and Radiotherapy and the more recent
appearance of Nuclear Medicine which uses radiopharmaceuticals to diagnose and
treat different diseases.
Together with surgery and pharmacology, radiotherapy is presently one of the
most important therapeutical weapons against cancer, which was estimated to affect
more than 3 million new patients in 2006 in Europe [
4
]. Radiotherapy and surgery
deal with cancer on a local/regional level, while pharmacology treats it at systemic
level. The development of radiotherapy since the first x-ray and cobalt treatment
equipments (see Fig.
24.1
) has implied the disappearance of mutilating surgical
techniques for achieving better results regarding both long-term tumour control and
treatment morbidity. Amongst others, this is true for malignant breast, head and
neck, prostata, and rectal tumours as well as sarcomas [
5
].
In 1990, the European Cancer Registry-Based Study of Survival and Care of
Cancer Patients (EUROCARE) was created. In one of its studies, it was observed
that patients diagnosed with cancer between 1995 and 1999 had an age-standardized
five-year relative survival rate of 50.3% [
6
]. Nowadays, the mean optimum irradi-
ation rate of cancer patients is estimated to be about 60% [
7
]. All this gives an
idea about the importance that the therapeutic utilization of ionizing radiations has
gained over the years.
In the last decades, advances have been achieved in cancer treatment. These
advances are related to certain circumstances such as the improvement in diag-
nostic and screening tools, a better interdisciplinary communication among cancer
surgeons, radiation oncologists, medical oncologists and pathologists, and a closer
interaction among physicians and other sciences allowing the transfer of clinically
useful biomedical discoveries and the emergence of cancer pharmacology. There is
no doubt that the future of radiation therapy is very promising.
24.1.2
Radiobiological concepts in radiation therapy
The application of radiation therapy is based on a selective depopulation of tumour
cells with the lowest possible damage to the surrounding normal tissues. In 1906,
