Brachytherapy

Brachytherapy is a form of radiation treatment delivery in which radiation emitting (radioactive) sources sealed inside a seed, pellet, wire, or capsule is implanted in the body using a needle or catheter. The radiation given off by this source damages the DNA of nearby cancer cells while limiting the dose to the surrounding normal structures.

Techniques for placing brachytherapy include:

Interstitial brachytherapy, in which the radiation source is placed within the tumor. This technique is used for gynecological cancers for instance.
Intracavity brachytherapy, in which the radiation source is placed within a body cavity. For example, radiation can be placed in the vagina, cervical or endometrial cavity to treat the respective cancers
Intraluminal brachytherapy is used to treat the esophageal and bronchial tumors by placing the catheter in the respective lumen and delivering the radiation.

The most common isotope used in brachytherapy is:

Iridium-192 or Cobalt 60: Usually takes the shape of a corn kernel and is about the same size as a rice grain but is produced initially as a wire. The half-life is 74 days for Ir192 and 5.26 years for Co60 which then transforms into stable daughter products.

The way brachytherapy is delivered varies depending on the type of cancer. But there are 2 main types:

High dose rate (HDR) brachytherapy
Low dose rate (LDR) brachytherapy

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 patients may have the applicators put in while under general anaesthetic. 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.

It may be delivered as:

a single treatment / day which may be repeated weekly to 3 to 4 times
several treatments over a number of days

Brachytherapy hardware

It houses the radioactive source (Iridium 192 or Cobalt 60) and when the connector tubes are connected with the brachytherapy hardware and the applicator in the patient the radioactive source moves from the hardware through the tube and into the applicator where it will treat the tumor and returns back to the hardware housing. This is an afterload brachytherapy whereby there is zero radiation risk to the healthcare workers.

Brachytherapy is an integral part in the treatment of various cancers including Gynecological cancers, Prostate cancers, Breast cancers, Head and neck cancers, esophageal cancers.

Brachytherapy is especially important in the treatment of gynecological cancers – a major killer of women in PNG. Nearly upto 400 cervical cancer patients (1500 treatment sessions) can be treated annually with this brachytherapy facility at PMGH cancer center.

There is a 25% increase in the overall survival with brachytherapy in the treatment of cervical cancer.

Need for brachytherapy services in PMGH was based on the IAEA imPACT review report (Sept 2023)

According to calculation (see below table), PNG will need 2 brachytherapy units to serve the needs of the whole nations’ need, calculated according to Zubizarreta’s method (Clin Oncol; 2015). These 2 units have already been planned to be installed in Angau Memorial Hospital and PMGH. Therefore, there will be no need to open another brachytherapy unit, and optimum management is to be ensured for sustainability of these 2 units in the long run.

The brachytherapy patient pathway