Use of radiation to treat cancer
Modern Day Advancements 1950 - Present Day
Cobalt-60 and the Megavoltage Era
Marking an important period of progression in the field of radiotherapy, the introduction of Cobalt-60 as an alternative to Radium sources which had been used in the past was a critical milestone. The understanding of radiation safety for both patients and medical professionals vastly improved, allowing treatments to be carried out at a lower risk, and improve research. Increasing dose strength of radiation was changed by the ease of production of Megavoltage photons through the decay of Cobalt-60, which laid down solid foundations for dose strength being scaled up over the following decades.
Brachytherapy Advancements in the 1970's
Following on from previous research into internal administration of radiotherapy and radiation, the 1970's marked a rapid growth in the technology involved in Brachytherapy. From automating delivery of radiation which improved safety and precision of the dose to pioneering treatments for prostate cancer, the experimental decade started a long road to improved internal treatment options. Although not all findings were safe and ready to be used at the time, as imaging technology improved, the discoveries were able to be implemented into effective, safe treatments.
Proton Beam Therapy
Approved by the FDA in 1988, Proton Beam Therapy involves targeting tumours with high energy beams of protons. Using a particle accelerator, protons are accelerated to approximately 2/3 the speed of light, and are then aimed using strong magnetic fields at the target site, where they can penetrate the body to around 30cm, depending on the speed produced by the particle accelerator. A particularly useful method of treating tumours in critical regions, the high precision of the beam allows higher doses to be administered, whilst minimising exposure to surrounding tissues.
Intensity modulated radiation therapy
Intensity modulated radiation therapy (IMRT) is a radiotherapy technique involving accurate 3D imaging along with bending and precisely directing several beams of varying intensities of radiation. Treatments are planned by studying 3D images of the tumour and using computer simulations to maximise the effective dose to the site. Combinations of many different beams with varying intensities produce a personalised radiation dose, taking account of the specific shape of the tumour and the sensitivity of the surrounding region to radiation treatment.
Image-guided radiation therapy
Image-guided Radiotherapy provides a mix between highly detailed imaging and the ability to deliver focused radiation. Clinicians image the tumour site with, for example ultrasound, X-rays or CT scans, and with the information gathered from these images, simulations are used to create a detailed treatment plan. The ability to create images just before treatment allows a more customised approach to be taken, but does also expose the patient to additional radiation. The precise imaging helps to improve the accuracy and precision of treatment, especially in more stationary areas of the body.
Stereotactic radiation therapy
By taking detailed 3D images of the patients tumour site, the exact size and shape can be determined. Stereotactic radiation therapy requires the patient to be precisely positioned and radiation beams so that radiation beams directed at the tumour can be delivered from a range of different angles and planes so that a high dose is concentrated at the target site, whilst healthy tissues are exposed only to a fraction of the intensity, helping to prevent unwanted damage. This technique is particularly useful when treating tumours in hard to reach areas, where the patient is unable to undergo surgery.
Radiopharmaceuticals
An emerging field combining both radiation and biological mechanisms, radiopharmaceuticals deliver treatment directly to the individual cells using binder molecules. This allows the target cells only to have radiation delivered to them, as the biological markers differ between different types of cell, preventing radiation from binding to healthy tissue. This has the potential to revolutionise personalised medicine as radiopharmaceuticals can be tailored to each different persons needs.