Western physicians faced an existential crisis in the 19th century. The new and rapidly expanded sciences of physiology, microbiology, histology, and microscopic pathology had rendered the Galenic principles, the basis of western medicine for two millennia, untenable. The time-honored practice of "balancing the humours" by purges, emetics, and bloodletting had become insupportable. But what was to replace it?
Many physicians turned to herbology, while others embraced homeopathy. There was a renewed interest in utilizing physical, rather than pharmacological, agents of therapy. Spa-immersion, massage, and sunbathing were re-introduced as hydrotherapy, chiropractics/osteopathy, and phototherapy. Electricity and ultra-violet light were used as agents of treatment. Within months of its discovery (1895), x-rays were applied to skin disease. They were found to have the capacity to eradicate certain dermatologic infections, birth defects, and even malignancies. The limitations of early x-ray tubes, including fluctuating output and limited capacity to penetrate tissue, confined their applicability to superficial lesions. The discovery of radium (1898), however, introduced a compact source of unvarying highly penetrating rays, suitable for external or internal application.
Initially, radium-therapy was the province of dermatologists and surgeons. The element was so rare (and expensive) that early practitioners used trivial, ineffective quantities. Initial enthusiasm was replaced by disappointment. But mass exploitation of American (later, African and Canadian) sources of radium ore resulted in the availability of sufficient quantities of the element for practical application. Thereafter progress was rapid, and by 1920 radium-therapy had displaced surgery as the preferred treatment for gynecologic malignancy.
The past century has witnessed dramatic advances in surgery and pharmacotherapy, but the implantation of radioactive sources has also evolved. Reactor and cyclotron-produced radionuclides, with higher specific activity and lower γ-ray/photon energy, have expanded applicability and patient safety. Computer dosimetry has improved the therapeutic ratio. Remote afterloading has eliminated radiation exposure to personnel. The 21st century is witnessing a renaissance of brachytherapy1.
1 The term 'brachytherapy' derives from the Greek word for 'short', brachy 
, referring to the distance between the therapeutic agent and the target lesion. The use of the Greek word in this context was introduced by Gösta Forssell. In a paper entitled La lutte social contre le cancer (Journal de Radiologie 1931;15:621-634), he referred to 'traitement à courte distance-pour lequel je propose la dénomination de traitement brachyradium' (short-distance treatment, for which I propose the name brachyradium).
