The development of radiotherapy: physics, technology methods.

Abstract

Radiotherapy was introduced in Sweden already before the turn of the century, ie, a few years after the discovery of x-rays and radioactivity. Pioneering contributions were made by Forssell, Berven, Heyman, Sievert, and Strandqvist in general radiotherapy, gynecologic radiotherapy, dosimetry, teleradium methods, and radiation biology. Technological advancements, along with nearly 100% followup of treatment effects, created a foundation for compiling early empirical experience in a methodologically sound specialty. Therapeutic radiology in Sweden was distinguished from diagnostic radiology already in 1917, at which time the specialties of general and gynecologic radiotherapy were founded. These specialties later developed into general and gynecologic oncology. Progress during recent decades has been characterized by access to better equipment such as telegamma devices and accelerators for external radiotherapy, and new radionuclides, eg, for remote controlled local application. With CT (computed tomography) and MRI (magnetic resonance imaging), SPECT and PET (tomography using gamma radiation and positron-irradiated nuclides), and ultrasound diagnostics, the anatomic basis for individual dose planning has radically improved. Dosage can now be planned with high precision and visualized in three dimensions using advanced computer programs. Technical safety has increased with improved methods for in vivo dosimetry and computer-controlled verification of all parameters for every treatment. It is now possible to deliver the intended radiation dose to a benign tumor without causing serious side effects. Important research fields include the impact of different fractionation schedules on the effects of radiation and how radiotherapy can best be combined with other forms of therapy such as surgery and chemotherapy.