The Evolution of Radiation Therapy Machines Essay Example

The Essence of Radiation Therapy

The basis of radiation therapy is the use of radioactive waves to affect the body cells. Radiation is the way the energy is transmitted in the space. It is divided into non-ionizing (such as heat or radio waves) and ionizing (such as ultraviolet and X-rays) radiation. Ionizing radiation bears significantly more power than non-ionizing because it can break chemical bonds within the matter. One of the examples of such power is that the X-rays are capable of making an atom lose its electrons. The exposure of a living cell to ionizing radiation causes its destruction. The discovery of this effect made physicians think about the usage of radiation to destroy cancer cells. Such treatment was called radiation therapy.

The essence of radiation therapy is in destroying the cancer cells without damaging the nearby healthy cells and organs. This procedure consists of a number of treatment sessions split into certain periods of time. This treatment might be used as primary or secondary when the radiation is used to destroy potentially dangerous cells. According to WHO, 52% of patients should undergo radiotherapy at least once during the treatment of cancer. On par with surgery and chemotherapy, radiation therapy played an important role to 40% of patients who were cured from cancer (World Health Organization, 2008). Thus, one may define the role of this method of treatment in contemporary medicine as critically important in the cases of cancer.

Types of Contemporary Radiation Therapy Machines

Contemporary radiation therapy includes various types of treatment. Among them, one can name an external-beam therapy, which is a classical way of exposing the patient’s organ to the radiating machine outside the body. The other typical way of treatment is an internal therapy, which means placing a radioactive segment into the area of the tissue affected by cancer. Moreover, modern medicine has more treatment options, such as intraoperative radiation therapy, systemic therapy, radioimmunotherapy, and the usage of radiosensitizers and radioprotectors (American Society of Clinical Oncology, 2013). The mentioned variety in means of treatment is a result of the constant development of radiation therapy. In order to realize the level of progress that this sphere reached over the time, one should consider its evolution.
The Past of Radiation Therapy

Radiation Therapy in the 1800s

The ideas to use radioactive rays in medical treatment appeared in the 19th century. Three subsequent events: the discovery of X-rays by Rontgen in 1895, the discovery of natural radioactivity by Becquerel in 1896, and the discovery of radium by Curie in 1898 opened the way for radiation therapy in medicine (Thariat, Hannoun-Levi, Sun Myint, Vuong, & Gérard, 2013). First speculations about the usage of radiation to treat diseases had been quickly put into practice. However, the very first attempts were mainly directed at skin lesions treatment. Such usage was caused by the lack of knowledge about the nature and capabilities of the discovered rays. Consequently, the first attempt to treat breast cancer with X-rays occurred in 1896 (Slater, 2012). From then on, medical scientists focused their studies on the investigation of the ways of the therapeutic applicability of electromagnetic particles. Slater claims that the early history of this development subsides into two eras: “the era of discovery, from Rontgen discovery to about the late 1920s” and “the orthovoltage era, from late 1920s through World War II” (2012). That is why one may state that the evolution of radiation therapy machines (RTM) greatly depended on the investigated substances and their ability to bear and transmit high voltage.

Experimenting with the Parameters of RTM at the Beginning of the 20th Century

The early stages of the radiation treatment development are associated with the lack of knowledge about the power of X-rays. Scientists were not aware of their biological effect and the behavior of the newly discovered rays. Moreover, they arranged experiments exposing themselves and their patients to high doses of radiation. That is how the negative side of radiation was discovered, and it was revealed that it can cause cancer as well as treat it. As a consequence, this stage of the development of a new method of treatment was associated with “much morbidity and poor cancer control” (Slater, 2012). Furthermore, the discovery of the components of radiation in physics raised the awareness about its dangerous effect on the healthy tissue. At this stage, physicians started to experiment with the dosage of radiation and its time of exposure. Various studies in this sphere led to the evolvement of fractionation, the approach that shifted the accent towards “dividing the dose into several smaller increments rather than administering a single massive dose” (Schreiber, 2013). This approach turned out to be efficient and has been approved to be one of the basic constituents of this method of treatment.

One more fact that significantly influenced the sphere of radiation therapy is the invention of a practical X-ray tube. This machine allowed exposing deep tumors to high-energy X-rays. This stage was promoted because of the invention of high-voltage transformers. The voltage was significantly lower than in modern machines and varied from 180 to 200 kV, but the fact of boosting the ability of the rays with high voltage opened big perspectives for the method. Its basic positive effects included the ability to focus on the targeted tissue, deeply impact it, and restrict a healthy tissue from being damaged by radiation. Radium 226 has been approved as a useful element for performing radiation therapy. That is why radium influenced the popularity of radiation therapy: “the first sources of supervoltage radiation were therefore telegamma apparatuses using radium” (Lakshmanan, 2003). However, the only advantage such machines had was the quality of the beam. Among the disadvantages one can mention the high cost of radium, large sizes, and inconvenient operation. That is why such devices did not gain a huge popularity among physicians. Further developments in this sphere were focused on the possibilities of raising the voltage of the machines and exploring new characteristics of radioactive rays.

Radiation Therapy in the Early-Mid 1900s

The ideas of the radioactive rays’ usage in medicine were further developed with the discoveries of physical properties of X-rays. Furthermore, this sphere has also been affected by the achievements in high-voltage production. The invention of the linear accelerator and cyclotron allowed designing the machines with the voltage up to 2 MV (Slater, 2012). The efficiency of such treatment was gradually rising, at the same time minimizing the effects of radiation on healthy tissues and maximizing it on tumors. Such RTM practitioners experimented with low-dose rates of radiation as well as developed different strategies based on treatment through the exposure to radium. Such studies were provided as an alternative to tumor surgery. “Some of their innovations, including intracavitary devices designed to treat uterine cervix tumors, bear remarkable similarity to modern brachytherapy applicators still in use today” (Connell & Hellmann, 2009). The functions of the machines included the ability to bombard the tumor from different angles, use several beans focused on the tumor, rotate the radioactive tube, and so on. Multibeam function was particularly useful: “each beam added radiation dose to the tumor, while spreading the dose received the normal tissues between the tumor and the surface of the patient” (Lakshmanan, 2003). Thus, from the 1920s and up to the 1940s, the changes in radiation therapy machines affected their structure and mechanics but not the voltage.

Acceleration of Radioactive Tubes as a Way of Improving the Technology of RTM

Furthermore, in 1940, with the development of betatron, a shift in the power of RTM occurred. This machine “produced 2 MeV electrons” (Slater, 2012). The introduction of a new way of accelerating the electrons was promising regarding its significant capabilities. The World War II discontinued the evolution of these devices because of the shift of the major companies to the military sphere. However, some of the researchers at that time still experimented with the machines. The reason for this was that a stable phase of the device ensured that “high energies could be achieved without the need to build ever larger cyclotrons. Phase stability became the basis for all high energy proton and electron accelerators thereafter” (Slater, 2012). This approach was important for RTM because it raised the level of acceleration, thus, allowing deeper penetration into the tumor.

Consequently, the usage of cobalt and the increase in the voltage of RTM triggered the emergence of megavoltage era that “encompasses the years from about 1950 to 1985” (Slater, 2012). The production of artificial radioactive elements, such as Cobalt-60, made the RTM inventors focus on their usage due to the ability to use elements with lower half-life and high level of emission. Thus, cobalt became “the work-horse of most radiotherapy departments in the 1960s and 1970s” (Lakshmanan, 2003). The usage of the element with a greater emission also allowed allocating the radioactive beam emitter and the patient located at greater distances. Furthermore, wedge fields were introduced. Being created from copper that absorbed radiation, they allowed directing the beam towards the edges of the damaged organ without affecting its healthy center. Among the drawbacks of the usage of cobalt as a radioactive emitter one can name the power of gamma radiation. First, the usage of cobalt as an emitter led to excessive radiation exposure of the patient. Further, means of spreading the radiation on larger fields of a healthy tissue led to the fact that the whole body was exposed to the radioactive emission.

The described stage in the development of RTM is significant because during that time the whole sphere of radiation therapy was transforming into a science. Shared experiences of various researchers and physicians allowed deciding upon the advances and drawbacks of this technology. Furthermore, cooperation in this sphere enabled overcoming serious issues and raising the efficiency of treatment. For instance, an MD Anderson Hospital has proved that “megavoltage treatment resulted in improved survival in cancer of the uterine cervix” (Slater, 2012). Consequently, as the scientists noticed, their methodology is directed towards oncology treatment; thus, the sphere of radiation therapy was shaping into radiation oncology.

Contemporary Radiation Therapy

Basic Information

Modern radiation therapy has encompassed the experience and knowledge of early stages of its development. That is why it is a comprehensive discipline that combines the best practices to achieve the best results in treatment and detection of diseases. The recent technical improvements made it possible to use such methods as volumetric modulated arc therapy and intensity modulated radiation therapy. Their advances include the usage of RTM, which allows to vary the intensity of radiation emission during the exposure, “and thus sophisticated dose painting is enabled” (Schreiner, 2011). Furthermore, machines delivering four-dimensional X-ray beam that allows focusing on the motion of the targeted organ are available. Another contemporary RTM allows performing adaptive radiation therapy that allows modifying the dosage of treating emission during the procedure according to the updated data. One more contemporary method of treatment is image-guided radiation therapy. The therapy allows obtaining live information about the tissue exposed to radiation, thus, leading the procedure towards the problematic field. A common feature of any contemporary methodology using RTM is the assistance of the latter. As stated by Gupta and Narayan,

The ability to image the patient in the treatment room immediately prior to irradiation presents many possibilities to generate a more accurate picture of the tumor’s extent and coordinates in 3D space… This information can provide motivation to keep patients immobile during treatment, reduce organ movement, and optimise irradiated volumes (2012).
Such machines and approaches are in contrast with the ones existing in the early days of radiation therapy treatment. The level of their safety is significantly higher, ensuring the protection of the patients from exceeding doses of radiation. Moreover, contemporary dosimetry techniques and equipment add to the mentioned contrast. For instance, the old technology of using ion chambers and radiochromic film tends to be substituted by the contemporary ones.

Modern Radiation Therapy Machines

It should be noted that the development of RTM is still in progress. As highlighted by Schreiner, the latest conferences of radiation therapists raise “a considerable interest in the promise of 3D measurement using new ion chamber/diode arrays arranged in non-planar geometry, and on gel and radiochromic plastic chemical dosimeters” (2011). Such devices and technology are of extreme importance for the patients, as they significantly improve the quality of treatment. Moreover, the usage of advanced RTM is crucial regarding the level of the spread of diseases. For instance, Ravichandran argues that “radiotherapy is one of the major modalities of cancer treatment and about 60% of these patients require radiation therapy as curative or palliative intent” (2009). Consequently, modern technological improvements in RTM allow implementing computer-based treatment and imaging. These methods allow creating specific models and operating a wide range of statistic data that enables predicting cancer. Connel and Hellmann (2009) highlight the revolutionary aspect of the latest improvements in the sphere of RTM. They argue that the modern humanity bears “a tremendous body of knowledge about cancer biology and how radiation affects human tissue on the cellular level” (Connel & Hellmann, 2009). Thus, there is no wonder that radiation treatment has become a casual method of treatment of various diseases of oncologic nature. Furthermore, the peculiarities of the transfer of RTM into the digital systems make the way of operating the worldwide data precise predictions in the treatment of oncology patients.

Opportunities and Drawbacks of Modern Radiation Therapy Machines

As it is proved with various data, contemporary RTM have made significant progress in both raising the efficiency of detecting malignant cells and targeting them with radioactive emission. However, new technologies have certain obstacles in their operation and implementation. For instance, such systems require an experienced staff of operators for the RTM to function properly and safely. Consequently, Brown argues that a contemporary digital RTM requires “The physician and the physicist … dosimetrist, radiation therapy technologist, and oncologic nurses” (2010). Thus, one of the possible drawbacks of such systems is the complexity of their operation. Moreover, the majority of the contemporary RTM have specific demands for infrastructure. For instance, some of them might be power volume or power stability demanding. Consequently, the exchange of the old RTM with the new ones could negatively affect their demand and supply ratio in regions with poor infrastructure. An example of such case in Bangladesh is given by Hussain and Sullivan: “There are only 15 linear accelerators installed in the country where two are installed in the rural area” (2013). Thus, the treatment with modern RTM might be unaffordable in regions with poor population. As explained by Ravichandran,
… replacements of existing tele-cobalt machines … leaving many patients not receiving treatments… There is a strong need to make policies to add more treatment machines in public funded institutions and improve the basic needs in these institutions, so that cancer care services are available to all sections of the society (2009).

Therefore, unfortunately, the public health sector cannot be regulated only with the advances in the development of RTM. There is a strong need in assessment of the economic level of local population with the aim of spreading such treatment regarding the level of income of the population.

Obstacles in the Usage of Modern Radiation Therapy Machines

One more problem of the contemporary RTM usage is, surprisingly, the safety of patients. This problem opposes the belief that modern advances in technology are completely safe. First, they require skillful and trained operators. Second, there is always a human factor that might involve a mistake during the operation of RTM. Moreover, some experts hold an opinion that modern technology can be “challenging, expensive, and time-consuming” (Joshi, 2014). For instance, there are fears that complicated digital interfaces may experience errors because of equipment malfunctions or software glitches. Thus, Salomons and Kelly (2013) argue about the need of software safety in the sphere of RTM. They assure that “the medical physics community is lacking the quality guidelines specific to the testing and use of software” (Salomons & Kelly, 2013). Apparently, the new technology successfully solves a number of old issues, at the same time raising the new ones. Moreover, the new RTM involve the increasing number of various data and parameters. Operating the pools of data raises the risks of errors from the side of the operator and physician. As a result, educating and training of the specialists in this sphere might require more time in contrast to RTM based on the old technology. Moreover, there is evidence that even modern RTM are incapable of avoiding complications in some organs. Thus, Gaya and Ashfold argue that there is “much evidence of cardiac complications resulting from radiotherapy to the mediastinum, oesophagus, gastro-oesophageal junction or breast” (2005). That is why one regards the existence of classical problems that could not be avoided even by the use of modern equipment.

The Perspectives Associated with Radiation Therapy Machines

The existence of the advanced technology in the sphere of radiation therapy supplied therapists and oncologists with a deep knowledge in detecting, imaging, evaluating, and treating diseases. Joshi stresses that with the assistance of such professionals, it is possible to “boldly contemplate a reduction in target volume margins, dose escalation with significant normal organ sparing, and design of novel clinical trials” (2014). Moreover, such technology might be significantly promoted in the future using the knowledge in genomics. For instance, Tran and Gillies argue that “radiogenomics application holds a future role in identifying tissue-specific radiation resistance and tolerance by identifying genes responsible for radiobiological response” (2010). Furthermore, one of the crucial perspectives in this sense is establishing a worldwide connection of radiation therapy equipment, gathered data, and specialists with the aim of sharing knowledge and experience. This priority should be implemented by the governments of all countries on par with the strategies managing water shortage, malnutrition, and other global health concerns (Rosenblatt, Acuna, & Abdel-Wahab, 2014). Such steps should be taken in order to raise the efficiency in resisting cancer and other diseases worldwide with the help of the modern RTM.

Conclusion

In conclusion, the discovery of radiation in the late 1800s has boosted the efficiency of medical treatment of certain diseases. Gradually, first radiation therapy machines emerged with the aim to treat various diseases. In the course of time, the knowledge about radiation emission has been increasing. Consequently, the medical community obtained all the necessary information about the influence of X-rays on the living cells. The advances and discoveries in physics let the researchers accelerate the radiation particles, which raised the quality of their impact on the living tissue. The end of the 20th century has brought completely new approaches to the essence of radiation therapy machines. Among the revolutionary approaches one can name the ability of real-time 3D modeling to reflect the impact of radiation on the exposed cells. Consequently, the complexity of the equipment and its transfer into the sphere of digital technology raises new challenges in medicine. However, disregarding all the challenges, the evolution of radiation therapy machines has brought the unique curing equipment to medicine. Radiation therapy allows treating cancer and various diseases of malignant nature with high efficiency and less harm compared to the machines from the beginning of the 20th century. Thus, the analyzed historical period reveals persuasive proofs that the evolution of radiation therapy machines significantly raised the efficiency of treatment of cancer and other diseases. Moreover, the development of radiation therapy machines still continues, enhancing the existing equipment, and thus, raising the quality of treatment.