| There are several ways of giving radiation | | | | |
| dosage to a cancerous tumor. The most common | | | | Brachytherapy can be delivered with devices |
| method is to deliver the required dosage from | | | | known as implants. These devices may be in |
| an external beam of radiation produced | | | | the form of needles or seeds or ribbons. |
| outside the body. In this case the source of | | | | Brachytherapy can be delivered with permanent |
| radiation beam is located 80-100 cm from the | | | | or temporary implants. These implants might |
| body of the person receiving radiation. | | | | be temporary or permanent. Temporary implants |
| Sometimes placing the source of radiation | | | | usually have a longer half-life and higher |
| within the tumor might have advantages over | | | | energies compared to the permanent implants. |
| delivering radiation from an external source. | | | | All temporary implants are inserted into the |
| This method of delivering required radiation | | | | tumor during surgery. The duration of |
| from an internal source embedded within the | | | | treatment for the temporary implant is |
| tumor is called brachytherapy. | | | | usually 1-3 days. |
| | | | |
| If you are aware of the inverse square law in | | | | Interstitial low-dose rate (LDR) |
| physics you would know the dosage of | | | | brachytherapy is usually used for cancers |
| radiation therapy delivery changes by a great | | | | involving the mouth and oral cavity, pharynx. |
| proportion depending upon the distance of the | | | | This mode of treatment is often used in the |
| radiation source to the intended target. In | | | | treatment of sarcomas. Prostate cancer |
| brachytherapy the source of radiation is | | | | treatment is the most common form of LDR |
| within the tumor volume and the proper | | | | brachytherapy using seeds. Uterine cancer is |
| placement of these sources of radiation | | | | the most common application of intracavitary |
| within the tumor is of crucial importance. | | | | LDR treatment. These patients are often |
| | | | isolated to prevent radiation exposure to |
| There are several radioactive isotopes used | | | | nursing and other supportive staff during the |
| in the brachytherapy. These include | | | | care of the person. |
| radium-226, cesium-137, cobalt-60, | | | | |
| iridium192, iodine-125, gold-198 and | | | | The most common uses of high-dose rate (HDR) |
| palladium-103. Radium has a longer half-life | | | | brachytherapy includes treatment of |
| compared to some of the other radioactive | | | | esophageal cancer, lung cancer and recently |
| isotopes. In the past radium was the primary | | | | breast cancer and prostate cancer. Most HDR |
| isotope used in brachytherapy, but recently | | | | treatments are done as outpatient procedures |
| radium has been largely replaced by cesium, | | | | allowing the patients to return to home the |
| gold and iridium, which have relatively | | | | same day as treatment. Patients who are |
| shorter half-life and lower energies and | | | | receiving treatment for prostate cancer is an |
| because of this the radiation from these | | | | exception who may remain in the hospital for |
| isotopes can be easily shielded. | | | | 2-3 days during the treatment. |