Radiation Oncology Victoria

What is HDR brachytherapy

High dose rate (HDR) is a technically advanced form of brachytherapy. A high intensity radiation source is delivered with millimeter precision under computer guidance directly into the tumor killing it from the inside out while avoiding injury to surrounding normal healthy tissue. HDR Brachytherapy is effective treatment of local disease in many forms of cancer including prostate, gynaecological, breast and anorectal. HDR Brachytherapy is a relatively new form of advanced radiation technology with fewer physicians having been trained to perform this compared to seed implantation or external beam radiation. The team at ROV are dedicated towards the development of HDR for prostate therapy and have a combined experience of well over 30 years in brachytherapy.

Who is suitable for HDR and why

HDR Brachytherapy can be used as the only treatment for prostate cancer or it can be used in combination with external beam radiation therapy (EBRT). Prostate HDR brachythreapy can be delivered with or without external beam radiation therapy (also known as HDR monotherapy). Basically, HDR monotherapy is reserved for prostate cancers that has recurred after prior radiation therapy. Combined HDR brachytherapy and EBRT is used for patients with more advanced disease within or around the prostate, those with higher PSA levels or higher pathology (Gleason 7-10) grade ie Intermediate risk to High risk prostate cancers. Delivery of EBRT expands the area of treatment beyond the prostate into other regions of the pelvis where microscopic deposits of disease may be present but undetected. HDR brachytherapy is delivered through the use of some small plastic catheters, which are directly inserted into the prostate gland. These plastic catheters act as a conduit allowing a radiation source to be directly placed within the prostate. Combined HDR and EBRT therapy patients undergo one HDR implants with three to four HDR radiation treatments (also called fractions). Once the radiation treatment has been delivered the catheters are easily pulled out and no radioactive material is left within the prostate gland.

How is HDR delivered?

At ROV, a state of the art computer-controlled machine called the Flexitron Robotic Afterloader pushes a radioactive iridium source, which is located on the end of a wire into each of the catheters. The radioactive iridium source is then positioned at a number of "dwell" positions to deliver the radiation dose within the prostate. These positions are determined with the aid of a planning computer allowing optimal dosage to the prostate. The treatment is individually tailored to the patient’s prostate cancer and surrounds by altering the "dwell" positions of the radioactive seed on the computer to give the best dose distribution within the prostate whilst minimising the dose to the urethra, bladder and rectum. The ability of dose to be modified after the plastic catheters are placed within the prostate is one of the major advantages of HDR brachytherapy. Approximately 2 weeks later a short (5.5 weeks) course of EBRT (Monday through Friday) is given. Published results on patients followed for at least 5 years have shown 90% clinical control of disease and high rates of freedom from PSA progression (a rising PSA) that vary according to the severity of disease.

What does the HDR procedure involve?

This procedure involves the insertion of 18 plastic hollow needles or catheters into the prostate. These are placed under a general anaesthetic under image guidance using transrectal ultrasonography and X-ray imaging. Once the plastic catheters are inserted, you will have a CT scan where imaging of the prostate and catheters is undertaken with subsequent computer planning allowing accurate calculation of the dose to be delivered and adjustment of the radioactive source positions within the prostate will be determined. Once the plan has been completed, the radioactive iridium source, which is housed in the after- loader, is delivered to the prostate. Although the patient is alone in the treatment booth, he is constantly monitored via closed circuit TV and intercom. The patient will hear the afterloader click and whir as the source is directed into each of the hollow plastic cathethers. The Iridium-192 source delivers the radiation dose in about 10 minutes. After the treatment, the source withdraws into the afterloader.

In total you will be in hospital for 2 days. Typically the needle placement is performed in the morning. A CT scan is performed by lunchtime and the planning is undertaken in the afternoon and the first treatment of HDR is delivered late in the afternoon of the first day. The following day the second treatment is delivered in the morning and the third in the afternoon. Once the treatment has been delivered the catheters can be removed and patient discharged the following morning. During the removal process, there is some slight bleeding, which is stopped by the nurse or therapist by applying firm pressure to the perineal area with gauze pads. During the 2 days the patient will remain in a hospital bed and will not be able to move significantly apart from rolling from side to side. In particular sitting up or walking will not be possible as that will place pressure on the protruding ends of the plastic hollow catheters. A urinary catheter will be inserted at the initial anaesthetic and removed at the end of the brachytherapy treatment. Approximately 2-3 weeks after the completion of the HDR brachytherapy a course of external beam radiation treatment to a moderate dose (50.4Gy in 28 separate treatment sessions) will be delivered over 5.5 weeks. Each session is given as an outpatient and usually only takes 20-30 minutes.

Side Effects of HDR:

The possible post-HDR acute side effects, usually lasting two to four weeks, are burning on urination, urinating more frequently, pain or feeling unable to pass urine freely is sometimes side effects. This usually is a limited side effect and uncommonly a urinary catheter may need to be used to alleviate symptoms. Typically this is related to swelling of the prostate causing blockage of the normal urinary outflow.

Slight bleeding, bruising and tenderness between the legs are common for a few days so activities like bicycle riding that put pressure on this area should be avoided. Medications are prescribed to help alleviate these temporary side effects.

Rectal discomfort is uncommon with respect to the HDR component of the treatment. Towards the end of the external beam radiation treatment some patients may experience temporary diarrhoea.

Long-term complications from the external beam radiotherapy at such moderate doses are uncommon. Incontinence is rare. The risk of developing impotency is thought to be approximately 30-40%. This is similar to other forms of radiation or brachytherapy, however long term results are not yet available.

Is HDR safe

Unlike permanent radioactive seed brachytherapy, HDR is only a temporary implant. After the procedure has been performed and the plastic needle catheters have been removed there will be no radioactivity within your body. You will not be radioactive. Your urine or other body fluids will not be radioactive.

Are you a candidate?

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