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The discovery of X-rays by Wilhelm Conrad Röntgen in 1895 set in motion research that led to the development of radiation therapy over a century ago. Initial uses of radiation focused on treating superficial cancers located on the skin. Advances in technology allowed higher radiation doses to penetrate deeper into the body to treat tumors throughout the decades. Major milestones included the invention of radium in the late 1890s and the creation of the cobalt bomb in the 1950s, both of which produced more powerful radiation beams than earlier tools. Today’s linear accelerators are able to precisely target tumors from a variety of angles while avoiding damage to healthy tissues.
Types of Radiation Therapy
There are several main types of external beam radiation therapy, which involves beams aimed at the cancer from a machine outside the body. The most common is intensity-modulated radiation therapy (IMRT), which uses computer-controlled X-ray beams to precisely target tumors while minimizing doses to nearby healthy tissue. Proton beam therapy focuses a beam of protons, rather than X-rays, to treat cancer and is particularly useful for tumors close to critical structures as protons deposit most of their energy at a specific depth. Stereotactic radiosurgery delivers a large, precise radiation dose in one treatment or a few treatments and is commonly used to treat brain and spinal tumors. Brachytherapy directly implants radioactive material in thin catheters or pellets near or inside the tumor.
Internal Radiation Therapy
For internal or implant radiation therapy, also known as brachytherapy, radioactive material is placed directly inside the body as close as possible to the cancer. There are two main types: low-dose-rate (LDR) and high-dose-rate (HDR) brachytherapy. For LDR brachytherapy, small radioactive seeds are placed in or near the tumor with a surgical procedure and left in place permanently or temporarily. With HDR brachytherapy, a specialized catheter is placed near the cancer and a radiation source is moved through the catheter and temporarily left in specific positions to deliver higher doses of radiation over minutes to hours. This allows higher radiation doses to be delivered precisely to the tumor while sparing normal tissues.
Efficacy and Side Effects
When used alone or combined with other treatments, radiation therapy can cure cancers or control cancer growth. Factors that affect its effectiveness include tumor size, location and stage. Side effects depend on the part of the body being treated but commonly include fatigue, skin irritation and temporary hair loss in treated areas. More serious though rare side effects may include damage to bowel or bladder tissues. When administered correctly by trained professionals using advanced techniques, therapies can deliver precise radiation doses to kill cancer cells while mostly avoiding harm to healthy tissues. Ongoing research continues to expand the benefits of radiation therapy.
New Advancements
Advances are helping improve cure rates and mitigate side effects. Image-guidance allows real-time X-ray images to verify patient positioning and tumor location before each treatment. Respiratory gating delivers radiation only at specific respiration phases to minimize motion-related uncertainties. Particle therapy precisely delivers radiation doses deep within tissues using protons or other ion beams instead of photons. Research on proton beams studies their ability to spare healthy tissues and increase tumor control. Development of flattening filter free photon beam delivery techniques aims to increase dose rates and reduce treatment times. Emerging magnetic resonance image-guided radiation therapy systems fuse MRI scanning with treatment delivery for ultra-precise targeting. These breakthroughs are enabling tight conformity of high-dose regions directly to tumors while minimizing irradiation of adjacent normal structures.
Future Possibilities
Scientists continue investigating new strategies to maximize cancer cell killing while minimizing harm to healthy cells during radiation therapy. One area of focus involves manipulating tumor biology using approaches like hypoxic cell sensitizers to enhance the effectiveness of radiation exposure. Combining radiation with immunotherapy seeks to leverage the ability of radiation to stimulate anti-tumor immune responses. Researchers are engineering nanoparticles that can be guided to tumors using magnetic fields to deliver higher doses of radiation specifically to cancer sites. Studies also probe the use of ultra-high dose rate flash radiation, selective brachytherapy and proton therapy to potentially improve outcomes. With further innovative technology and clinical research, radiation therapy will likely evolve into an even more precise and personalized treatment with fewer side effects to benefit many more cancer patients worldwide.
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1. Source: Coherent Market Insights, Public sources, Desk research
2. We have leveraged AI tools to mine information and compile it
