of radiation dose to tumor with sparing of nearby normal tissue. brachytherapy followed ebrt or surgery have been shown to improve the survival rate and local recurrent rate than ebrt or surgery only for esophageal cancer patients. skin cancer hdr brachytherapy for nonmelanomatous skin cancer, such as basal cell carcinoma and squamous cell carcinoma, provides an alternative treatment option to surgery. this is especially relevant for cancers on the nose, ears, eyelids or lips, where surgery may cause disfigurement or require extensive reconstruction.: ch. 28 various applicators can be used to ensure close contact between the radiation source(s) and the skin, which conform to the curvature of the skin and help ensure precision delivery of the optimal irradiation dose.: ch. 28 another type of brachytherapy which has similar advantages as the hdr is provided be the rhenium-sct (skin cancer therapy). it makes use of the beta ray emissions of rhenium-188 to treat basal cell or squamous cell carcinomas. the radiation source is enclosed in a compound which is applied to a thin protective foil directly over the lesion. this way the radiation source can be applied to complex locations and minimize radiation to healthy tissue. brachytherapy for skin cancer provides good cosmetic results and clinical efficacy; studies with up to five years follow-up have shown that brachytherapy is highly effective in terms of local control, and is comparable to ebrt. treatment times are typically short, providing convenience for patients. it has been suggested that brachytherapy may become a standard of treatment for skin cancer in the near future. blood vessels brachytherapy can be used in the treatment of coronary in-stent restenosis, in which a catheter is placed inside blood vessels, through which sources are inserted and removed. in treating in-stent restenosis (isr) drug eluting stents (des) have been found to be superior to intracoronary brachytherapy (icbt). however, there is continued interest in vascular brachytherapy for persistent restenosis in failed stents and vein grafts. the therapy has also been investigated for use in the treatment of peripheral vasculature stenosis and considered for the treatment of atrial fibrillation. side effects the likelihood and nature of potential acute, sub-acute or long-term side-effects associated with brachytherapy depends on the location of the tumour being treated and the type of brachytherapy being used. acute acute side effects associated with brachytherapy include localised bruising, swelling, bleeding, discharge or discomfort within the implanted region. these usually resolve within a few days following completion of treatment. patients may also feel fatigued for a short period following treatment. brachytherapy treatment for cervical or prostate cancer can cause acute and transient urinary symptoms such as urinary retention, urinary incontinence or painful urination (dysuria). transient increased bowel frequency, diarrhoea, constipation or minor rectal bleeding, may also occur. acute and subacute side effects usually resolve over a matter of days or a few weeks. in the case of permanent (seed) brachytherapy for prostate cancer, there is a small chance that some seeds may migrate out of the treatment region into the bladder or urethra and be passed in the urine. brachytherapy for skin cancer may result in a shedding of the outer layers of skin (desquamation) around the area of treatment in the weeks following therapy, which typically heals in 5–8 weeks.: ch. 28 if the cancer is located on the lip, ulceration may occur as a result of brachytherapy, but usually resolves after 4–6 weeks. most of the acute side effects associated with brachytherapy can be treated with medication or through dietary changes, and usually disappear over time (typically a matter of weeks), once the treatment is completed. the acute side effects of hdr brachytherapy are broadly similar to ebrt. long-term in a small number of people, brachytherapy may cause long-term side effects due to damage or disruption of adjacent tissues or organs. long-term side effects are usually mild or moderate in nature. for example, urinary and digestive problems may persist as a result of brachytherapy for cervical or prostate cancer, and may require ongoing management. brachytherapy for prostate cancer may cause erectile dysfunction in approximately 15–30% of patients.: ch. 20 however, the risk of erectile dysfunction is related to age (older men are at a greater risk than younger men) and also the level of erectile function prior to receiving brachytherapy. in patients who do experience erectile dysfunction, the majority of cases can successfully be treated with drugs such as viagra.: ch. 20 importantly, the risk of erectile dysfunction after brachytherapy is less than after radical prostatectomy. brachytherapy for breast or skin cancer may cause scar tissue to form around the treatment area. in the case of breast brachytherapy, fat necrosis may occur as a result of fatty acids entering the breast tissues. this can cause the breast tissue to become swollen and tender. fat necrosis is a benign condition and typically occurs 4–12 months after treatment and affects about 2% of patients. safety around others patients often ask if they need to have special safety precautions around family and friends after receiving brachytherapy. if temporary brachytherapy is used, no radioactive sources remain in the body after treatment. therefore, there is no radiation risk to friends or family from being in close proximity with them. if permanent brachytherapy is used, low dose radioactive sources (seeds) are left in the body after treatment – the radiation levels are very low and decrease over time. in addition, the irradiation only affects tissues within a few millimeters of the radioactive sources (i.e. the tumour being treated). as a precaution, some people receiving permanent brachytherapy may be advised to not hold any small children or be too close to pregnant women for a short time after treatment. radiation oncologists or nurses can provide specific instructions to patients and advise for how long they need to be careful. types different types of brachytherapy can be defined according to (1) the placement of the radiation sources in the target treatment area, (2) the rate or 'intensity' of the irradiation dose delivered to the tumour, and (3) the duration of dose delivery. source placement the two main types of brachytherapy treatment in terms of the placement of the radioactive source are interstitial and contact. in the case of interstitial brachytherapy, the sources are placed directly in the target tissue of the affected site, such as the prostate or breast.: ch. 1 contact brachytherapy involves placement of the radiation source in a space next to the target tissue.: ch. 1 this space may be a body cavity (intracavitary brachytherapy) such as the cervix, uterus or vagina; a body lumen (intraluminal brachytherapy) such as the trachea or oesophagus; or externally (surface brachytherapy) such as the skin.: ch. 1 a radiation source can also be placed in blood vessels (intravascular brachytherapy) for the treatment of coronary in-stent restenosis. dose rate the dose rate of brachytherapy refers to the level or 'intensity' with which the radiation is delivered to the surrounding medium and is expressed in grays per hour (gy/h). low-dose rate (ldr) brachytherapy involves implanting radiation sources that emit radiation at a rate of up to 2 gy·h−1. ldr brachytherapy is commonly used for cancers of the oral cavity, oropharynx, sarcomas: ch. 27 and prostate cancer: ch. 20 medium-dose rate (mdr) brachytherapy is characterized by a medium rate of dose delivery, ranging between 2 gy·h−1 to 12 gy·h−1. high-dose rate (hdr) brachytherapy is when the rate of dose delivery exceeds 12 gy·h−1. the most common applications of hdr brachytherapy are in tumours of the cervix, esophagus, lungs, breasts and prostate. most hdr treatments are performed on an outpatient basis, but this is dependent on the treatment site. pulsed-dose rate (pdr) brachytherapy involves short pulses of radiation, typically once an hour, to simulate the overall rate and effectiveness of ldr treatment. typical tumour sites treated by pdr brachytherapy are gynaecological: ch. 14 and head and neck cancers. duration of dose delivery the placement of radiation sources in the target area can be temporary or permanent. temporary brachytherapy involves placement of radiation sources for a set duration (usually a number of minutes or hours) before being withdrawn.: ch. 1 the specific treatment duration will depend on many different factors, including the required rate of dose delivery and the type, size and location of the cancer. in ldr and pdr brachytherapy, the source typically stays in place up to 24 hours before being removed, while in hdr brachytherapy this time is typically a few minutes. permanent brachytherapy, also known as seed implantation, involves placing small ldr radioactive seeds or pellets (about the size of a grain of rice) in the tumour or treatment site and leaving them there permanently to gradually decay. over a period of weeks or months, the level of radiation emitted by the sources will decline to almost zero. the inactive seeds then remain in the treatment site with no lasting effect. permanent brachytherapy is most commonly used in the treatment of prostate cancer. procedure typical stages of a brachytherapy procedure initial planning to accurately plan the brachytherapy procedure, a thorough clinical examination is performed to understand the characteristics of the tumour. in addition, a range of imaging modalities can be used to visualise the shape and size of the tumour and its relation to surrounding tissues and organs. these include x-ray radiography, ultrasound, computed axial tomography (ct or cat) scans and magnetic resonance imaging (mri).: ch. 5 the data from many of these sources can be used to create a 3d visualisation of the tumour and the surrounding tissues.: ch. 5 using this information, a plan of the optimal distribution of the radiation sources can be developed. this includes consideration of how the source carriers (applicators), which are used to deliver the radiation to the treatment site, should be placed and positioned.: ch. 5 applicators are non-radioactive and are typically needles or plastic catheters. the specific type of applicator used will depend on the type of cancer being treated and the characteristics of the target tumour.: ch. 5 this initial planning helps to ensure that 'cold spots' (too little irradiation) and 'hot spots' (too much irradiation) are avoided during treatment, as these can respectively result in treatment failure and side-effects. insertion before radioactive sources can be delivered to the tumour site, the applicators have to be inserted and correctly positioned in line with the initial planning. imaging techniques, such as x-ray, fluoroscopy and ultrasound are typically used to help guide the placement of the applicators to their correct positions and to further refine the treatment plan.: ch. 5 cat scans and mri can also be used.: ch. 5 once the applicators are inserted, they are held in place against the skin using sutures or adhesive tape to prevent them from moving. once the applicators are confirmed as being in the correct position, further imaging can be performed to guide detailed treatment planning.: ch. 5 creation of a virtual patient creation of a virtual patient to plan the delivery of brachytherapy the images of the patient with the applicators in situ are imported into treatment planning software and the patient is brought into a dedicated shielded room for treatment. the treatment planning software enables multiple 2d images of the treatment site to be translated into a 3d 'virtual patient', within which the position of the applicators can be defined.: ch. 5 the spatial relationships between the applicators, the treatment site and the surrounding healthy tissues within this 'virtual patient' are a copy of the relationships in the actual patient. optimizing the irradiation plan refinement of the treatment plan during a brachytherapy procedure to identify the optimal spatial and temporal distribution of radiation sources within the applicators of the implanted tissue or cavity, the treatment planning software allows virtual radiation sources to be placed within the virtual patient. the software shows a graphical representation of the distribution of the irradiation. this serves as a guide for the brachytherapy team to refine the distribution of the sources and provide a treatment plan that is optimally tailored to the anatomy of each patient before actual delivery of the irradiation begins. this approach is sometimes called 'dose-painting'. treatment delivery the radiation sources used for brachytherapy are always enclosed within a non-radioactive capsule. the sources can be delivered manually, but are more commonly delivered through a technique known as 'afterloading'. manual delivery of