Brachytherapy
Derived from ancient Greek words for short distance (brachios) and treatment (therapy) and refers to the therapeutic use of encapsulated radionuclides within or close to a tumor. It is sometimes called seed implantation and is an outpatient procedure used in the treatment of different kinds of cancer.
Two general types of radiation techniques are used clinically - brachytherapy and external beam radiation therapy (teletherapy).
It is clear that brachytherapy is the optimum way of delivering conformal radiotherapy tailored to the shape of the tumor while sparing surrounding normal tissues.The efficacy of brachytherapy, as compared with the efficacy of external beam alone, is attributable to the ability of radioactive implants to deliver a higher concentrated radiation dose more precisely to tissues, which contributes to improved local control, provided that the tissue is clinically delimitable and accessible. At the same time, the surrounding healthy tissues are spared irradiation.
In contrast to external-beam irradiation, brachytherapy is invasive, requiring insertion of site-specific applicators under sedation or anaesthesia. The surgeon who is sometimes involved in these procedures, particularly if laparotomy or craniotomy is required for the insertion of applicators, or if tumour resection is required prior to applicator insertion, should be aware of the indications for brachytherapy and the associated techniques.
Brachytherapy is an internal radiation therapy that is applied either in a permanent manner, (sometimes called seed implantation), or in a temporary manner, often through the use of catheters into which the radioactive sources are placed. The radioactive materials (seeds or in catheters) are placed inside the body, and positioned in a manner that will most effectively treat the disease. When permanent brachytherapy is being employed, the radioactive “seeds” are left inside of the body. The half-life of the radioactive isotope used, gauges how long they will be radioactive within the body since the radioactivity of the seeds diminishes over time. Temporary brachytherapy usually involves either an in-patient procedure (low dose rate brachytherapy, or LDR, pulse dose rate brachytherapy, or PDR), whereby the patient lies in bed for several days while the radioactive sources treat the disease, or in an out-patient setting (high dose rate brachytherapy, or HDR, whereby the patient usually undergoes several treatments of radiation in a short period of time.
Indications for brachytherapy.
a. prostate brachytherapy
Prostate brachytherapy usually involves an out-patient procedure for either permanent seed implantation or HDR brachytherapy to the prostate gland. It has been shown to have comparable 10-year survival rates to radical prostatectomy, and has fewer side effects including a lower incidence of impotence and incontinence.
According to the American Cancer Society, prostate cancer is one of the most common forms of cancer among American men, mainly affecting men over the age of 65. As men get older, the likelihood of developing prostate cancer increases, therefore, physicians usually recommend that prostate cancer screening begin at age 50. For African American men, or men with a family history of prostate cancer, physicians recommend screening beginning at age 40.
b. breast brachytherapy
Treatment of breast cancer with brachytherapy usually involves a five-day treatment course with either LDR (in-patient) or HDR (out-patient) brachytherapy, rather than six weeks as with traditional radiation treatment following a lumpectomy. This offers excellent cure rates without the need for a mastectomy.
Breast conservation treatment has long since been established as an effective treatment alternative to mastectomy for early stage breast cancer. Standard breast conservation treatment consists of breast conserving surgery for tumor removal (lumpectomy) followed by external radiation to the whole breast. Although this treatment approach offers many advantages over mastectomy and provides in-breast cancer control rates that approach 95-100% with good to excellent cosmetic results in nearly all patients, six weeks of daily treatment has proved prohibitive for some patients. As a result, some women refuse external radiation (putting themselves at higher risk for recurrence) or choose mastectomy and have the breast unnecessarily removed. Those finding six weeks of daily treatment inconvenient or impossible include working women, elderly patients, and those who live a significant distance from a treatment center. Breast brachytherapy as the sole method of radiation following lumpectomy is a new treatment approach that offers equivalent local control, breast conservation and improved convenience of treatment delivery. Although most women with breast cancer are appropriate candidates for standard breast conservation treatment and can be treated with lumpectomy and external radiation, only a subgroup of these women will be appropriate candidates for breast brachytherapy. However, even with strict selection criteria it is estimated that 71,000 women each year in USA would be appropriate candidates for breast brachytherapy.
c. cervical brachytherapy
Historically, cervical cancer has been treated with a hysterectomy (the surgical removal of the uterus), which carries many side effects for the patient. Brachytherapy is usually used in combination with external beam radiation therapy in the treatment of cervical cancer and has been found to be at least as effective as a hysterectomy.
d. head and neck brachytherapy
The use of brachytherapy in the treatment of head and neck cancers causes practitioners hesitation, owing to the proximity to vital structures including the carotid arteries, the jugular veins, other major blood vessels and in some cases the brain. There is a limited amount of clinical data available but, there are several safe and efficacious ways to use brachytherapy in the treatment of head and neck cancers.
e. skin brachytherapy
f. lung cancer
The use of brachytherapy in the treatment of lung cancer dates to the 1920s, though the applications varied widely. Brachytherapy is one of the most efficient methods in the overcoming difficulties in breathing caused by endobronchial obstruction in palliative treatment of lung cancer. Depending on the location of the lesion in some cases brachytherapy is a treatment of choice. Because of the uncontrolled local or recurrent disease, patients may have significant symptoms: cough, dyspnoea, haemoptysis, obstructive pneumonia or atelectasis. In many patients, these symptoms are primarily attributable to endobronchial obstruction. Efforts to relieve this obstructive process are worthwhile because patients may experience a significantly improved quality of life. However, many of these patients have a poor performance status and have received multiple other therapies. As a result, treatment options are often limited.
In most cases brachytherapy has a palliative aim due to the advanced clinical stage. Lack of clear consensus regarding the value of doses used in brachytherapy is the reason why different fraction doses are used in clinical treatment.
g. oesophageal brachytherapy
The aim of palliative brachytherapy is to reduce dysphagia, diminish pain and bleeding, as well as improve the patient’s well-being. Endoesophageal brachytherapy makes it possible to use high doses of radiation to the tumour itself with concurrent protection of the adjoining healthy tissues due to the rapid fall in the dose with the square of the distance from the centre of the dose. The above treatment also leads to a smaller proportion of late radiation complications.
However, there have been only few reports to confirm that the number of local remissions and long-term survival rates have been increased in patients treated with teletherapy combined with brachytherapy. Doses used in teletherapy were as high as 35-60 Gy, whereas those in HDR brachytherapy ranged between 10 and 25 Gy administered in 2-4 fractions. The combined treatment can be radical or palliative. Positive results of HDR brachytherapy have been observed in patients who had not been treated surgically. In these patients, the radioisotope source is inserted through the mouth to the esophagus if the applicator can be passed through the stenotic region. In general, in brachytherapy a sufficient dose distribution in the tumour can only be achieved in tumours that are smaller than 1.5 cm in diameter, and only in patients whose esophageal lumen is kept sufficiently wide to allow passage of the applicator.
h. brain brachytherapy
Brachytherapy for recurrent malignant gliomas represents an increasing part of indications for brachytherapy in central nervous system tumors. Indications for brachytherapy are tumors with a maximum tumor diameter of 5 cm without involvement of the corpus callosum, without brain stem involvement, not in proximity with the motor trip. Primary malignant tumors, recurrent brain tumors, metastatic brain tumors and benign brain tumors have been considered for brachytherapy.
i. soft-tissue sarcomas
Brachytherapy can be used alone or in combination with external beam radiation therapy for soft tissue sarcomas as an effective means to enhance therapeutic ratio (ratio of effectiveness when compared to toxicity of treatment).
j. brachytherapy is also used to treat coronary artery disease and external artery restenosis to prevent restenosis after angioplasty. Early clinical studies indicate that intravascular brachytherapy can help reduce the rate of restenosis after angioplasty procedures. Based on these results, devices for intracoronary brachytherapy have been approved by the FDA for widespread use.
External Beam Radiation Therapy
The term external beam radiation therapy refers to the use x-rays (or photons) delivered externally (outside the body) to whatever area of the body is being treated with the radiation. The x-ray/radiation treatments that you receive will be just like any other x-ray that you may have had, but the "energy" of the x-ray beam will be different, because these x-rays are therapeutic (a form of treatment), rather than diagnostic (for taking pictures). You will not feel the radiation in any way. It will not hurt, and it will not make you feel hot, or cause you to be "radioactive" in any way. You will simply lie on a hard, flat table in the same position every day. The radiation treatment machine, called a linear accelerator, will rotate around you, treating from multiple directions, to deliver the painless radiation. You may hear the sound of the treatment machine while it is on, often described as a "humming" or "clicking sound."
EBRT will typically require you to come to the hospital daily (Monday – Friday) for treatment for several weeks at a time. Usually treatment lasts for about 30 minutes a day, including the time it takes to enter the department, change, get set-up on the treatment table, actually receive the radiation, and exit the department. The number of weeks will vary for each patient, but the treatment commonly requires approximately eight weeks of your time. You will undergo a "simulation," or planning session, initially that will include a CT scan. The CT scan is not intended to be a diagnostic x-ray; it is only used for the purpose of planning the radiation. In some cases, your radiation oncologist may recommend that tiny markers or seeds that are non-radioactive be implanted into the prostate gland to help with targeting of the radiation.
3-D Conformal Radiotherapy (3DCRT)
3-D conformal radiation therapy is all of the treatment planning for your radiation which will be done based on a planning CT scan. The CT scan is used to outline the prostate or target area, as well as any surrounding normal tissues, such as the bladder and rectum. The x-ray beams are arranged according to the CT outlines.
In brachytherapy, the radiation device is placed within or close to the target volume. Teletherapy uses a device located at a distance from the patient, as is the case in most orthovoltage or supervoltage machines. The advent of high voltage teletherapy for deeper tumors and the problems associated with radiation exposure from high-energy radionuclides led to a decline in the use of brachytherapy towards the middle of last century.
However, over the past three decades, there has been renewed interest in the use of brachytherapy for a number of reasons. The discovery of man-made radioisotopes and remote afterloading techniques has reduced radiation exposure hazards. Newer imaging modalities (CT scan, magnetic resonance imaging, transrectal ultrasound) and sophisticated computerized treatment planning has helped to achieve increased positional accuracy and superior, optimized dose distribution. Finally, while brachytherapy was initially used only for treatment of cancer, it has now been found to be useful in non-malignant diseases (for example, in the prevention