MODULE V: MODALITY SPECIFIC MANAGEMENT
EXTERNAL BEAM RADIATION THERAPY
External beam radiation therapy comes from a machine that aims radiation at cancer. It is a local treatment, which means it treats a specific part of the body. For example, if a patient has cancer in the lung, the patient will have radiation only to the chest, not to the whole body. External beam radiation therapy is used to treat many types of cancer.
Types of beams used in radiation therapy
Radiation beams used in external radiation therapy come from three types of particles:
💦photons
💦protons
💦protons
💦electrons
Photons
Most radiation therapy machines use photon beams. Photons are also used in X-rays, but X-rays use lower doses. Photon beams can reach tumours deep in the body. As they travel through the body, photon beams scatter little bits of radiation along their path. These beams do not stop once they reach the tumour but go into normal tissue past it.
Protons
Protons are particles with a positive charge. Like photon beams, proton beams can also reach tumours deep in the body. However, proton beams do not scatter radiation on their path through the body and they stop once they reach the tumour. Doctors think that proton beams might reduce the amount of normal tissue that is exposed to radiation. Clinical trials are underway to compare radiation therapy using proton beams with that using photon beams. Some cancer centres are using proton beams in radiation therapy, but the high cost and size of the machines are limiting their use.
Electrons
Electrons are particles with a negative charge. Electron beams cannot travel very far through body tissues. Therefore, their use is limited to tumours on the skin or near the surface of the body.
Types of external beam radiation therapy
There are many types of external beam radiation therapy, all of which share the goal of delivering the highest prescribed dose of radiation to the tumour while sparing the normal tissue around it. Each type relies on a computer to analyze images of the tumour to calculate the most precise dose and treatment path possible.
Types of external beam radiation therapy include:
💢 3-D conformal radiation therapy
3-D conformal radiation therapy is a common type of external beam radiation therapy. It uses images from CT, MRI, and PET scans to precisely plan the treatment area, a process called simulation. A computer program is used to analyze the images and to design radiation beams that conform to the shape of the tumour.
Mechanism of working
3-D conformal radiation confirms the shape of the tumour by delivering beams from many directions. The precise shaping makes it possible to use higher doses of radiation on the tumour while sparing normal tissue.
Treatment schedule
Most people have treatment once a day. The number of treatments varies from person to person based on details about the cancer, such as the type and stage of cancer and the size and location of the tumour.
💢 Intensity-modulated radiation therapy (IMRT)
IMRT is a type of 3-D conformal radiation therapy.
Mechanism of working
Like 3-D conformal radiation, radiation beams are aimed at the tumour from several directions.
IMRT uses many smaller beams than 3-D conformal and the strength of the beams in some areas can be changed to give higher doses to certain parts of the tumour.
Treatment schedule
Most people have treatment once a day. The number of treatments varies from person to person based on details about the cancer, such as the type and stage of cancer and the size and location of the tumour.
💢 Image-guided radiation therapy (IGRT)
IGRT is a type of IMRT. However, it uses imaging scans not only for treatment planning before radiation therapy sessions but also during radiation therapy sessions.
Mechanism of working
During treatment, the patient will have repeated scans, such as CT, MRI, or PET scans. These scans are processed by computers to detect changes in the tumour's size and location. Repeated imaging allows for the position or the radiation dose to be adjusted during treatment if needed. These adjustments can improve the accuracy of treatment and help spare normal tissue.
Treatment schedule
Most people have treatment once a day. The number of treatments varies from person to person based on details about the cancer, such as the type and stage of cancer and the size and location of the tumour.
💢 Tomotherapy
Tomotherapy is a type of IMRT that uses a machine that is a combination of a CT scanner and an external-beam radiation machine.
Mechanism of working
Tomotherapy machines take images of the tumour right before treatment sessions to allow for very precise tumour targeting and sparing of normal tissues. It rotates around the patient during treatment, delivering radiation in a spiral pattern, slice by slice. Tomotherapy might be better at sparing normal tissue than 3-D conformal radiation therapy, but it has not been tested in clinical trials to be sure.
Treatment schedule
Most people have treatment once a day. The number of treatments varies from person to person based on details about the cancer, such as the type and stage of cancer and the size and location of the tumour.
💢 Stereotactic radiosurgery
Stereotactic radiosurgery is the use of focused, high-energy beams to treat small tumours with well-defined edges in the brain and central nervous system. It may be an option if surgery is too risky due to your age or other health problems or if the tumour cannot safely be reached with surgery. Gamma Knife is a type of stereotactic radiosurgery.
Mechanism of working
Patients will be placed in a headframe or some other device to make sure do not move during treatment. In stereotactic radiosurgery, many small beams of radiation are aimed at the tumour from different directions. Each beam has very little effect on the tissue it passes through, but a precisely targeted dose of radiation is delivered to the site where all the beams come together.
Treatment schedule
Treatment schedules can vary, but treatment is usually given in one dose. In some cases, the patient may receive up to five doses, given once per day.
💢 Stereotactic body radiation therapy
Stereotactic body radiation therapy is similar to stereotactic radiosurgery, but it is used for small, isolated tumours outside the brain and spinal cord, often in the liver or lung. It may be an option when you cannot have surgery due to age, health problems, or the location of the tumour.
Mechanism of working
As in stereotactic radiosurgery, stereotactic body radiation therapy uses special equipment to hold you still during treatment. It delivers a highly precise beam to a limited area.
Treatment schedule
Tumours outside of the brain are more likely to move with the normal motion of the body, such as with breathing or digesting. Therefore, the radiation beams cannot be targeted as precisely as they are in stereotactic radiosurgery. For this reason, stereotactic body radiation is usually given in more than one dose. The patient may have up to five doses, given once per day.
How often do patients have external beam radiation therapy?
The duration of treatment depends on the type of cancer, the goal of treatment, the radiation dose, and the radiation schedule.
The period from the first radiation treatment to the last is called a course of treatment.
Researchers are looking at different ways to adjust the radiation dose or schedule to reach the total dose of radiation more quickly or to limit damage to healthy cells.
Different ways of delivering the total radiation dose include:
Accelerated fractionation: which is treatment given in larger daily or weekly doses to reduce the number of weeks of treatment.
Hyper fractionation: which is a smaller dose than the usual daily dose of radiation given more than once a day.
Hypo fractionation: which are larger doses given once a day or less often to reduce the number of treatments.
Researchers hope these different schedules for delivering radiation may be more effective and cause fewer side effects than the usual way of doing it or be as effective but more convenient.
Pre-treatment interventions
💧 Physical examination
💧 Medical history
💧 Imaging tests
💧 Discuss external beam radiation therapy, its benefits and side effects
💧 A radiation oncologist and radiation therapist will figure out the treatment area. The treatment area is referred to as the treatment port or treatment field. These terms refer to the places in the body that will get radiation. Patients will be asked to lie still while X-rays or scans are taken.
💧 The radiation therapist will tattoo or draw small dots of coloured ink on the skin to mark the treatment area. These dots will be needed throughout radiation therapy. The radiation therapist will use them to make sure the patient is in exactly the same position for every treatment. The dots are about the size of a freckle. If the dots are tattooed, they will remain on the skin for the rest of the patient's life. Ink markings will fade over time. Be careful to educate the patient not to remove them and tell the radiation therapist if they fade or lose colour.
💧 A body mould may be made of the part of the body that is being treated. This is a plastic or plaster form that keeps the patient from moving during treatment. It also helps make sure that the patient is in exactly the same position for each treatment.
💧 If the patient getting radiation to the head and neck area may be fitted for a mask. The mask has many air holes. It attaches to the table where the patient lies for the treatments. The mask helps keep the head from moving so that the patient is in exactly the same position for each treatment.
External beam radiation therapy will not make the patient radioactive. The patient may safely be around other people, even pregnant women, babies, and young children.
INTERNAL BRACHYTHERAPY
Brachytherapy, also called internal radiation therapy, places radioactive material directly inside or next to the tumour.
It uses a higher total dose of radiation to treat a smaller area than external beam radiation therapy (EBRT) which directs high-energy X-ray beams at a tumour from outside the body.
Types of brachytherapy
The way the patients have brachytherapy varies depending on the type of cancer the patients have. But there are 2 main types:
👉 High dose rate (HDR) brachytherapy
👉 Low dose rate (LDR) brachytherapy
👉 Permanent
High-dose-rate brachytherapy
With high dose rate brachytherapy, the radioactive source is put in the body for several minutes. The radioactive source travels from the brachytherapy machine through hollow tubes or needles (called applicators) to get to the right position. The patient may have the applicators put in while under general anaesthesia.
After 5 to 20 minutes of treatment, the source travels back along the applicators to the brachytherapy machine and the patient is no longer radioactive.
Low-dose-rate brachytherapy
with low-dose-rate brachytherapy, the patient has a lower dose of radiation over a longer time. The patient might have the radioactive source in place for up to a week. The patient should stay in the hospital during this time in the room. After treatment, the doctor removes the radioactive source and the patient can go home. Once the source is taken away the patient is no longer radioactive.
There is a type of low-dose-rate brachytherapy called permanent seed brachytherapy for prostate cancer. The radioactive source is in the form of tiny metal seeds that are left in the prostate forever. The seeds slowly give off radiation over a few months. The patient can be at home after having the seeds put in. But as a patient slightly radioactive for a time, have to avoid very close contact with children and pregnant women.
Permanent
Permanent radioactive implants release radiation continually, and the level of radioactivity quickly decreases over time until they become inactive. The implants, or seeds, which are about the size of a grain of rice, remain in the body. This treatment is also called seed implantation. At first, healthcare providers may restrict interactions as the patient give off radiation. Over time, patients should be fine to interact with others without exposing themselves to radiation.
Indications
💢 Brain cancer
💢 Breast cancer
💢 Cervical cancer
💢 Eye cancer
💢 Gallbladder cancer
💢 Head and neck cancers
💢 Lung cancer
💢 Prostate cancer
💢 Rectal cancer
💢 Skin cancer
💢 Thyroid cancer
💢 Uterine cancer
💢 Vaginal cancer
Preparation
💦 Physical examination
💦 Review medical history- Review medicines, past and present conditions, and prior surgeries. Verify the patient is pregnant or breastfeeding.
💦 Imaging, such as a magnetic resonance imaging (MRI) or computed tomography (CT) scan.
💦 Stop taking medications that affect blood clotting, such as blood thinners (anticoagulants) or nonsteroidal anti-inflammatory drugs (NSAIDs).
💦 Use a bowel preparation (enema) before the procedure.
💦 Do not drink or eat anything for several hours before the procedure.
💦 Quit using tobacco products.
Procedure:
The procedure depends on cancer, the type of brachytherapy (LDR, HDR or permanent) and where the implants are placed:
Intracavity brachytherapy: Implants are placed near the tumour inside a body cavity, like the vagina.
Interstitial brachytherapy: Implants are placed directly inside the tumour.
Regardless of the procedure, the patient may receive medicines to keep the patient relaxed. The patient may get a sedative and anaesthesia to relieve pain and discomfort. Once the patient is comfortable, the doctor will:
Insert a catheter (small flexible tube) or applicator device that will be used to send the radioactive implants to the tumour. Imaging (X-ray, ultrasound or MRI) can help ensure correct placement.
Send the implant through the catheter or applicator device until it reaches the tumour. How long the implant stays depends on the type of brachytherapy.
In HDR, removes the implant after treatment sessions. In LDR, the implant may be removed after each treatment session and re-inserted during future sessions, or the provider may leave it in place throughout treatment.
Patients receive pain medications to ease any discomfort once it’s time to remove the catheter or applicator device.
What to expect after brachytherapy
The patient generally won’t feel much pain during and after a procedure to place brachytherapy implants. The patient may be given a sedative or general anaesthesia. Once the radiation device has been implanted, may feel some discomfort or tenderness around the area.
Some patients go home soon after their procedure, while others need to stay at the hospital for a few days. The exact timeline depends on the type of brachytherapy and whether the implants are temporary or permanent.
If receive permanent LDR brachytherapy with small implants, may be able to discharge after the procedure. After a few weeks or months, these implants will no longer give off radiation.
With HDR brachytherapy, treatment may be given once a week over a couple of weeks, but some patients receive multiple treatments a day, possibly over a couple of days, in which case they stay in the hospital until it’s completed.
Disadvantages of Brachytherapy
As with any cancer treatment, brachytherapy can cause unpleasant side effects. Most side effects improve once treatment stops, but some are long-term or don’t appear until after treatment ends.
How effective is brachytherapy?
Brachytherapy is a highly effective treatment for certain types of cancer. It’s most effective on cancers that haven’t spread, or metastasized. Most side effects improve as the radiation leaves the body.
Follow up Education
Instruct the patient to contact the healthcare provider if they experience any of the following symptoms during treatment:
💦 Trouble breathing or swallowing
💦 Severe stomach upset, vomiting or diarrhoea
💦 Urinary incontinence
💦 Faecal incontinence
Total Lymphoid Irradiation
Total lymphatic irradiation (TLI) is radiation therapy given to the lymphatic system. TLI uses high-energy X-rays. TLI is an important part of some stem cell (bone marrow) transplants.
The lymphatic system is part of the immune system. Normally, having a strong immune system is good. But the immune system can also attack the new, healthy donor cells the person gets in a transplant. TLI helps turn off the immune system for a short time, so it will not harm the new cells.
Doctors use chemotherapy and TLI together to prepare for the transplant. TLI may occur before, during, or after chemotherapy. It usually includes 4 doses.
Pre-Treatment Evaluation:
About 1-2 weeks before TLI, the patient will meet with the radiation oncologist. The radiation oncologist will explain TLI and discuss the benefits and potential side effects.
Get consent from the parents or guardians for TLI.
Before the treatment, the patient will go through simulation and treatment planning. These are done to ensure that:
💥 the treatment site is mapped out,
💥 patient gets the right dose of radiation, and
💥 the dose to nearby tissue is minimized.During the simulation, the patient will have x-rays and the skin will be marked. These marks define the area to be treated. The simulation takes two to four hours.
Possible Early Side Effects of TLI
Early side effects can happen shortly after the start of TLI and up to 6 months after TLI ends. They include:
💦Fatigue
💦Nausea and vomiting
💦Diarrhoea
💦Loss of appetite
💦Skin redness
💦Dry skin
💦Hair loss in the treated area
Possible Late Side Effects of TLI
Late side effects can happen 6 months or longer after TLI. They can include:
💦 Changes in normal growth and development
💦 Having fewer than normal certain types of blood cells
💦Changes in the function of the heart, lungs, liver, or kidneys
💦 Hormone problems
💦 Infertility
💦 Other cancers
Patient Education during TLI
💥 Remove jewellery and contact lenses for TLI.
💥Give medicines as instructed to control nausea and vomiting.
💥Do not wash off any pen marks used for positioning or shielding until the TLI treatments are over.
💥Do not use oil-based creams or lotions on the days of TLI. Some lotions can interfere with treatment. Use only lotions that are ordered by the care team until the last treatment is over. Then, use creams or lotions as recommended to keep the skin soft and moist.
💥Take care of the skin. Use mild soaps. Avoid deodorant soaps. Do not use hot blow dryers on the skin or scalp.
💥Always use sunscreen with 30 SPF or higher and limit sun exposure when possible.
Total Skin Irradiation
Total skin irradiation is a type of RT that is delivered to the entire skin surface with electrons and is referred to as total skin electron beam therapy.
Indications
Total skin irradiation is most commonly used in the treatment of cutaneous T-cell lymphoma, which incorporates two major subgroups.
💢 Mycosis fungoides
💢 Sezary syndrome
Total skin irradiation may be a localized treatment in patients with unilateral or localized mycosis fungoides, lymphoma cutis, and Kaposi sarcoma.
Total skin irradiation may be part of a non-myeloablative allogeneic HSCT.
Procedure
Boost treatment may be given to areas of ulceration prior to total skin irradiation.
treatment typically is delivered via a 6MeV electron beam, and the patient is placed in a standing position in front of the beam.
External or internal eye shields may be used to protect the cornea and lens.
Treatment typically is delivered four days a week for 30-45 minutes over the course of six to eight weeks for a total dose of 36-40 Gy to the skin and 18-20 Gy to the hands and feet.
Possible Acute Side Effects
💦Patients will experience epithelial reactions, including pruritus, erythema, dry desquamation, and moist desquamation.
💦Superficial atrophy with wrinkling, telangiectasia, xerosis, and uneven pigmentation are the most common changes.
💦 Patients may experience pain related to skin changes.
💦 Patients will experience alopecia, which is irreversible in four to six months.
💦 Nail loss.
💦 At higher doses (greater than 25 Gy), some patients may develop transient swelling of the hands, oedema of the ankles, and occasionally large blisters, necessitating local shielding or temporary discontinuation of therapy.
💦 Patients may report an inability to sweat properly for the first 6-12 months following therapy.
💦Gynecomastia may develop; the mechanism for this is unknown.
Possible Late Side Effects
💦Superficial atrophy with wrinkling, telangiectasia, xerosis, and uneven pigmentation are the most common changes.
💦Although rare, higher doses may cause permanent alopecia, frank poikiloderma (mottled skin appearance), skin fragility, and subcutaneous fibrosis.
Patient and Family Education
💦Teach the patient and family about the treatment procedure, the time required for the treatment each day, and the positioning used for the treatment.
💦Inform the patient and family that the majority of the treatment area will be exposed during the treatment, and measures will be implemented to protect the patient's privacy.
💦Teach male patients about the potential risk of infertility caused by the dose received to the testes and options such as sperm banking.
💦Teach the patient about eye rinses to minimize irritation from eye shields.
💦Teach the patient and family about the use of skin products to minimize dry pruritus and dry desquamation.
💦Teach the patient and family about skin care if blisters or moist desquamation arises.
💦Teach the patient and family to elevate the extremity if swelling or oedema arises.
💦Teach the patient and family about performing skin checks and to report any new lesions or changes in lesions.
💦Emphasize to the patient and family the importance of follow-up care to assess for late effects.
Proton Beam Radiation Therapy
Proton Beam Therapy is a type of radiotherapy. It uses protons, which are small parts of atoms, rather than high-energy X-rays. This particular type of radiotherapy enables a dose of high-energy protons to be targeted directly at a
tumour whilst significantly reducing the dose to surrounding healthy tissues and vital organs.
How does proton therapy work?
💦The proton begins its journey at the ion source. Within fractions of a second, hydrogen atoms are separated into negatively charged electrons and positively charged protons.
💦The protons are injected via a vacuum tube into a linear accelerator and in only a few microseconds, the protons’ energy reaches 7 million electron volts.
💦Proton beams stay in the vacuum tube as they enter the synchrotron, where acceleration increases their energy to a total of 70 million to 250 million electron volts, enough to place them at any depth within the patient’s body.
💦After leaving the synchrotron, the protons move through a beam-transport system comprised of a series of magnets that shape, focus and direct the proton beam to the appropriate treatment room.
💦To ensure that each patient receives the prescribed treatment safely and efficiently, the facility is controlled by a network of computers and safety systems. The gantry can revolve 360 degrees, allowing the beam to be delivered at any angle.
💦As protons come through the nozzle, a custom-made device (the aperture) shapes the beam of protons, and another custom-made device (the compensator) shapes the protons into three dimensions, delivering them to the depth of the tumour.
💦At maximum energy, a proton beam travels 125,000 miles per second, which is equivalent to two-thirds the speed of light.
💦From the hydrogen canister to the patient, a proton typically travels 313,000 miles.
In general, a proton radiation treatment lasts about 15 to 30 minutes.
Benefits of Proton Therapy
Compared with X-ray radiation therapy, proton therapy has several benefits:
💦Lower risk of radiation damage to tissues
💦Higher radiation dose to the tumour, with the better likelihood that all tumour cells are destroyed
💦Fewer and milder side effects such as low blood counts, fatigue, and nausea during and after treatment
Proton therapy also may be used to treat these cancers:
💦Central nervous system cancers, including chordoma, chondrosarcoma, and malignant meningioma
💦Eye cancer, including uveal melanoma or choroidal melanoma
💦Head and neck cancers, including nasal cavity and paranasal sinus cancer and some nasopharyngeal cancers
💦Lung cancer
💦Liver cancer
💦Prostate cancer
💦Spinal and pelvic sarcomas, which are cancers that occur in the soft tissue and bone
💦Noncancerous brain tumours
Side effects of proton therapy:
The treatment itself is painless. Afterwards, the patient may experience fatigue.
Other side effects include these problems on affected skin:
💦Redness
💦Irritation
💦Swelling
💦Dryness
💦Blistering and peeling
Patients may experience other side effects, especially if they are also receiving chemotherapy.
The side effects of proton therapy depend on the part of the body being treated, the size of the tumour, and the types of healthy tissue near the tumour.
The difference between proton and photon therapy:
💦Traditional radiation delivers x-rays, or beams of photons, to the tumour and beyond it. This can damage nearby healthy tissues and can cause significant side effects.
💦By contrast, proton therapy delivers a beam of proton particles that stops at the tumour, so it’s less likely to damage nearby healthy tissues.
💦Some experts believe that proton therapy is safer than traditional radiation, but there is limited research comparing the two treatments.
Patient and Family Education
💦Explain the difference between proton and photon radiation and how proton beam RT works.
💦Provide information on the immobilization device and the importance of patient positioning and compliance.
💦Describe simulation and daily treatment. Include the treatment schedule and any special instructions necessary for daily treatment.
💦List possible side effects and symptom management strategies.
💦Provide information on communication with the treatment team.
💦Confirm understanding by the patient and family and document.
REFERENCES:
https://www.cancer.org/cancer/managing-cancer/treatment-types/radiation/internal-radiation-therapy-brachytherapy.html
https://www.cancer.gov/about-cancer/treatment/types/radiation-therapy/brachytherapy
http://www.bccancer.bc.ca/our-services/treatments/radiation-therapy/internal-radiation-therapy
https://www.cancer.gov/news-events/cancer-currents-blog/2020/proton-therapy-safety-versus-traditional-radiation#:~:text=Traditional%20radiation%20delivers%20x%2Drays,to%20damage%20nearby%20healthy%20tissues.
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