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Articles: Science | About Cancer Treatment !!!
- Mr. Pamulaparti Venkata Phaneendra
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Early radiotherapy consisted of a single massive dose of radiation, typically lasting an hour. Side effects were severe. In 1914, an Austrian doctor controversially suggested that radiotherapy might work better if it was given in many smaller doses ('fractionated radiotherapy'). This sparked a debate that lasted until 1922, when Claudius Regaud conclusively proved that fractionated therapy was just as effective as single-dose therapy, but caused fewer side effects.
The 1920s also saw the emergence of the radiographer as a specialist profession. Despite these advances, radiotherapy was predominantly used to alleviate symptoms ('palliative' treatment) rather than actually cure cancer.
Over the next thirty years, engineers built ever more powerful x-ray sources. The more powerful an x-ray, the further into the body it penetrates and the less damage it does to the skin. X-ray energies are measured in Kilovolts (KV) or Megavolts (MV; 1MV = 1000KV).
In the 1920s, x-ray generators were only capable of making x-rays at about 200KV (for comparison, the natural gamma-rays emitted by radium are about 1.2MV). By the 1950s, engineers had developed an 8MV x-ray generator (or 'linear accelerator'). Nowadays, an x-ray machine in a typical hospital will have an energy of about 10MV.
Since then, a number of technological developments have allowed radiologists to target the x-ray beam more accurately and avoid damaging normal tissue, further improving radiotherapy as a cancer treatment.
For example, the use of CT scanning allows radiologists to determine the exact size and shape of the tumour. And fractionated radiotherapy techniques such as CHART, developed by Cancer Research UK scientists in the 1990s, have been proved to increase survival and produce fewer side effects.
Another type of radiotherapy is internal radiotherapy or brachytherapy. This technique involves implanting tiny beads or rods of radioactive metal around the tumour. It too has been in use since the early 1900s, and is still in use today. Initially, radium was the metal of choice for brachytherapy, but these days, caesium and iridium are used instead.
Radiotherapy is usually required for one of the following reasons:
• As a stand-alone treatment to cure cancer;
• To shrink a cancer before surgery;
• To reduce the risk of a cancer coming back after surgery;
• To complement chemotherapy;
• To control symptoms and improve quality of life if a cancer is too advanced to cure.
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