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Types


Brachytherapy is at the forefront of innovation in radiotherapy

State-of-the-art treatment

Significant developments have been made over the last 20–30 years in computing and imaging techniques, such as ultrasound, computed tomography (CT) and magnetic resonance imaging (MRI).

These developments have been invaluable in improving the quality of brachytherapy offered to cancer patients. Their introduction has led to improvements in treatment planning, implementation and assessment, resulting in efficacy and tolerability benefits for patients.


imaging modalities

Key trends in brachytherapy include:

  • A move from 2D (i.e. film-based) to 3D (i.e. volume-based) planning techniques, using imaging techniques such as CT and MRI.
  • Introduction of 4D planning (3D plus time).
  • Combining planning and treatment techniques in a one-step process (real-time planning), rather than using a separate planning step (pre-planning).

The use of multiple imaging techniques can help improve the treatment delivery process, and allow for real-time changes to the radiation dose and the position of the radiation sources. These ongoing advances in brachytherapy continue to improve outcomes and efficiency.

Compared with other radiotherapy techniques, such as EBRT and intensity modulated radiation therapy (IMRT), only brachytherapy provides a highly targeted, effective, established and cost-effective radiation therapy, without compromising on the risk of toxicity.


catheter reconstruction and dose optimization

Types of source placement

The delivery of radiation sources to the target tumor area is performed via specialized applicators such as catheters or needles that are directly inserted into either:

  • A body cavity (e.g., uterus, vagina), body lumen (e.g., trachea, oesophagus) or external surface (e.g., skin)  – collectively referred to as contact brachytherapy.
  • The tumor (e.g., prostate, breast) – referred to as interstitial brachytherapy.


Types of source duration

The sources can be left in place temporarily or permanently:

  • Temporary brachytherapy delivers the radioactive source to the treatment site for a set time, typically minutes, before being withdrawn.
  • Permanent brachytherapy involves implanting “seeds” or “pellets”, each about the size of a grain of rice, into the tumor – this technique is also called ’seed therapy’.  The radiation gradually depletes over a period of about a year.


Types of dose rate

Brachytherapy can deliver radiation at various intensities, which are measured in grays per hour (Gy/h):

  • Low dose rate (LDR) brachytherapy delivers radiation with a low level of intensity (<2 Gy/h), making it safe for permanent brachytherapy.
  • High dose rate (HDR) brachytherapy delivers radiation at a much greater level of intensity (>12 Gy/h) and is always temporary, enabling treatments to be both quick and effective.
  • Pulsed dose rate (PDR) brachytherapy delivers radiation in short pulses to enhance the effectiveness of LDR treatment.  PDR brachytherapy is mostly used for gynaecological and head and neck cancers. 


References
  1. Prostate Cancer published by Raconteur Media in The Times, 28 October 2009.
Page last updated on 14 January 2011.

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