External Radiation Therapy
External Radiation Therapy
Radiation Therapy For Cancer
Radiation therapies are also known as radiotherapy. These are used to treat cancers, by focusing high-dosages of radiations towards cancerous tissues. Such radiations are aimed at shrinking of cancers and or to destroy tumor cells. In most cases, high dosages are prescribed as a part of radiation therapies.
At such high intensity radiations, DNA of diseased cells are damaged forever, in an irreversible manner. Upon being damaged – at the DNA–level – such cells stop growing. Once growth is denied, cells tend to eventually die off. Dead cells are flushed out of your system in due course of time.
Radiation therapy is not known to destroy tumour causing cells immediately. It often needs many days – spanning several weeks, for DNA to be damaged, and cause cell-level death. dying process often takes weeks i.e., long after radiotherapy sessions are over.
Radiation Oncology
Radiation oncology is of two (2) major kinds; 1- external beam radiation and 2- internal radiation. This kind of therapy offered to you varies based on multiple factors – namely, type of tumors, size of cancers, location of cancer(s) in your body, how near is the cancer to healthier / normal tissues that may turn sensitive to high intensity radiations, your overall clinical history and onset of other kinds of tumors in your system – if any, your age and presence of others ailments – if any, etc.
Of these two (2) kinds of radiation therapy, external beam radiation emanates from an equipment which targets cancerous growth. This equipment is often a very large one, and can be quite noisy as well. This machine does not make any form of physical contact with you; instead, it moves all around your body transmitting high intensity rays from multiple directions.
Radiotherapy For Cancer
Radiation therapy for cancer using external beam is a localised treatment protocol, used for treating tumors in specific sites / organs of the human body. For instance, those diagnosed with cancers in their lungs are administered with external beam radiations on their chest region; in other words, rays do not target any other parts / sites apart from the chest area.
On the other hand, internal radiation therapy is a treatment offered through sources of x-rays placed inside the human body. Sources of such radiations can be either be a liquid or a solid source. Therapies offered with solid radiation sources are known as brachytherapy.
Here, a capsule, ribbon or a seed containing a radiation source is placed deep inside i.e., near or inside the cancerous site. Similar to external beam radiation therapy, internal radiation therapies – such as brachytherapy – are a localised treatment protocol. This approach help treat a particular site of the human body.
Sources of radiation in case of internal radiation therapies may provide radiations for some time. Internal radiation therapies – done with liquid sources of radiations – are known as systemic therapies. Here, the rays transcend the blood barrier with ease – throughout the human body, identifying and destroying tumorous cells.
Systemic therapies are offered either by making you to swallow the liquid source of radiation, or by an intravenous route. In some cases, liquid is administered into your body via an injection. In this treatment protocol, bodily fluids such as sweat as well as urine will send off radiations for some time.
External Beam Radiation Therapy
External beam radiation therapies involve delivering high intensity electron-based rays / x – ray beams. These rays are made by an equipment called linear accelerator – in short, linac. Physicians who administer these x– rays are called radiation oncologists. These specialists work out a bespoke / customised external beam radiation-based treatment plan. These plans help map out sites needing treatments, and aim to kill harmful / rapidly-growing cells.
It is imperative of plans to spare normal / healthier tissues while they aim to kill cancerous cells. Such therapies are deemed curative in nature – their efficacy get a boost with chemotherapy and / or surgical interventions. External beam radiation therapy is also used for obtaining relief from pains triggered by cancerous conditions.
It is the team of radiation oncologists that determines the intensity of x- ray radiations. The team’s decision is taken based on the stage your cancer is in and type of tumour you are affiliated by. Your team also looks into outcomes of scan images, lab reports and also a physical examination of your body.
Image Guided Radiation Therapy – in short, IGRT – helps augment the resolution of images. This approach helps target the destination with added precision. In this process, the extent of damages inflicted upon healthier and unaffected cells is sizably minimised.
Another Technical Advancement is Volumetric Modulated Arc Therapy – also known as VMAT. Here, a linear accelerator (linac) is made to rotate around your body. This makes rays to enter into your system from various sides. This is extremely useful to minimise exposure risks on to adjoining tissues and organs i.e., of the non-cancerous kind.
As a Recent Addition – present forms of linear accelerators are equipped with collimators. This equipment serves as a shield, safeguarding nearby organs. Multi-leaf collimator has more than 100 leaves; each leaf helps block some of the radiation field. As a result, the exposed area can be mapped identical to the affected surface of the human body. The earlier versions of linear accelerators were devoid of collimators. In such cases, hand-made block-type settings are used to minimise risks of overexposure on to organs at risk.
Radiation Therapy Side Effects
Your body may encounter a few side effects upon being exposed to radiation therapies. If radiation therapy is used for treating brain tumors, you may witness loss of scalp hair, severe spells of migraines, blurring of eyesight, inability to concentrate on things, memory lapses, etc. Those getting radiation treatment for cancers in breast may see swelling or inflammation, being tired at almost all times, changes on skin, softening of muscles, etc.
If you have cancers in the chest region i.e., lungs, and if your oncological team is using radiation therapies – the side effects include throat-related problems, difficulties in swallowing foods, intermittent episodes of coughing, inability to breath property – marked by gasping, wheezing and panting.
Use of radiation therapies for cancers in head and neck region may lead to a few adverse effects. These are oral / dental problems, a marked change in the sense of taste, hoarseness of voice accompanied by several other throat-centric conditions, hypothyroidism – due to the gland turning slow and dysfunctional.
Use of radiation for tumors developing in the pelvic zone can cause sexual dysfunction – in males, this can take the shape of erectile dysfunction, loss of libido, etc., among women, fertility-related issues may show up. You may also observe weakening of the urinary bladder and incontinence. In some cases, patients may report experiencing frequent urges to pee or painful spells of urination. In some very remote instances, you may experience inability to discharge urine.
In the stomach and abdominal tract, use of external beam radiation therapies may engender severe episodes of nausea coupled with vomiting, loss of body hair, discharge of loose stools, being fatigued all through the day – and sleeping for long, altered skin tone, etc.
Tumors in rectum – upon being treated with external beam radiation therapies – may lead to fertility problems in women, discharge of softened stools, urinary conditions like painful experiences while peeing, etc.
Every session of radiation therapy will involve marking your posture with lasers, to ensure maximum accuracy. You may also undergo a scanning protocol, prior to each session. Scanning is done either by a computer tomography (CT) scan or an ultrasound. There are also instances wherein x-rays are used.
Each sitting may need 50 – 60 minutes per day. A majority of it is used for alignment, and for scanning to enhance accuracy–levels. Usually, therapies last for scores of sittings; of these, the first sitting is often the longest one. Subsequent sessions may only take 25 to 30 minutes. Actual exposure time within which linear accelerator delivers radiations is only 3 to 7 minutes.
Duration of exposure also varies based on the use of image guided radiation therapy (IGRT), size of site / organ under treatment, intensity of dosages, etc. Based on the type(s) of cancers, oncologists may focus radiations from multiple directions. Depending on stage of cancer, timing of exposure is either lengthened or shortened.
It is likely each session of therapy may almost take similar timespan. Radiation–sittings are usually planned only–once per day. Within a week, you may be advised to take 4 – 5 sittings. Your cancerous condition determines the length of treatment plans; duration hovers anywhere between 3 – 10 weeks’ time.
Disclaimer
Information provided here are only of supplementary nature. Information shared here does not substitute a qualified doctor’s advice. This website is not suggesting that intake of a drug(s) or a treatment modality is safe or appropriate. You are urged to consult with a qualified clinical professional and get a treatment plan from her / him for the underlying medical condition(s).
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Shetty B s a cardiologist in Chennai, with extensive experience in the field. He completed his MBBS from Madurai Kamaraj University, followed by an MD in General Medicine and a DM in Cardiology from The Tamil Nadu Dr. M.G.R. Medical University (TNMGRMU).