Brachytherapy is done in the following cases:

1. For the treatment of several types of cancers
2. Before surgery, to shrink the tumor size 
3. After surgery, to destroy the remaining cancer cells
4. In conjunction with other types of cancer treatments, like chemotherapy, immunotherapy, and external beam radiation

Brachytherapy can help in the treatment of the following types of cancers:

• Brain cancer
• Breast cancer
• Cervical cancer
• Endometrial cancer 
• Bile duct cancer
• Eye cancer
• Lung cancer
• Esophageal cancer
• Head and neck cancers
• Pancreatic cancer
• Skin cancer
• Prostate cancer
• Vaginal cancer 
• Rectal cancer
• Soft tissue cancers

The following diagnostic tests may be advised before a brachytherapy procedure:

1. Physical examination: The doctor checks the physical health, symptoms, and medical history of the patient.
2. Blood tests: Certain medical conditions can be checked using blood tests.
3. Imaging tests: Imaging tests like CT scans and MRI scans help in obtaining clear images of the suspected cancerous organ.
4. Endoscopy: A tube having a camera on one end, known as an endoscope, is used to check an organ internally.
5. Biopsy: The suspected tissue growth is excised surgically and sent to the laboratory to check if cancer cells are present, and the type of cancer cells that may be present.

Implants used for a brachytherapy procedure are either put in their place by a catheter (a small, stretchy tube) or an applicator (a larger device). The catheter or applicator is put into the patient’s body before brachytherapy treatment is started.
There are different techniques that can be used to place brachytherapy implants, which may include the following:

1. Interstitial brachytherapy: This procedure involves the placement of the radiation source within the tumor, like within the prostate or breast.
2. Intracavitary brachytherapy: This procedure involves the placement of the radiation source within a body cavity or a cavity created by surgery, like the windpipe or vagina.
3. Episcleral brachytherapy: This procedure involves the attachment of the radiation source to the eye. It is used to treat melanoma of the eye.
4. After the catheter or applicator is put in its place, the radiation source is placed inside it. The source of radiation may be kept in its place for a few minutes, for many days, or for the remaining part of the patient’s life, depending on the type of cancer being treated, the type of radiation source used, location of cancer, the patient’s health status, and the other types of cancer treatments that the patient may be undergoing.

Brachytherapy may be associated with the following side effects:

• Fatigue
• Difficulty in urinating
• Urinary incontinence (involuntary urine leakage)
• Erectile dysfunction
• Hair loss
• Bowel incontinence (involuntary stool passage)
• Diarrhea
• Constipation
• Mouth sores
• Headaches
• Nausea
• Vomiting
• Dyspnea (shortness of breath)
• Cough

The body's radiation source may give off radiation for some time after the brachytherapy procedure. It is necessary to take the following precautions after the brachytherapy procedure:

• The patient needs to stay in a private hospital room and protect other people from radiation that may come from the patient’s body.
• Hospital visits by other people should be avoided completely or be done only after wearing protective gear and at a minimum safe distance.
• The patient should avoid having any contact with young children or pregnant women.
• The catheter or applicator is removed after treatment completion.
• The doctor prescribes certain pain-relieving medications before removing the catheter or applicator.
• It is normal for the patient to have some soreness for a few months in the region of the catheter or applicator placement.
• After the removal of the catheter or applicator, there is no radiation in the patient’s body and it is safe for other people to be near the patient.
• The patient needs to limit his/her daily activities for a week or two after the brachytherapy procedure.
• The doctor recommends follow-up visits and scans to check how successful was the brachytherapy treatment.