THE CHRISTIE BECOMES THE FIRST HOSPITAL IN THE UK TO PROVIDE PDR BRACHY GYNAE FOR ITS PATIENTS WITH GYNAECOLOGICAL CANCERS

The Christie Hospital recently switched from Low Dose Rate (LDR) to Pulsed Dose Rate (PDR) Brachytherapy.  It has now decommissioned LDR and is running at full capacity, treating patients clinically using PDR which delivers radiation in short ‘pulses’ over several hours.  The source used is typically a one Curie Iridium192 source, assembled and driven in the same way as High Dose Rate treatments.  The hospital is using a Nucletron microSelectronafterloader treatment delivery platform.

The principle behind PDR is that it is biologically similar to traditional LDR techniques, where sources are loaded into catheters and applicators, with the source being left in place for a number of hours or days.  This means that PDR treatments are delivered on an ‘in-patient’ basis and require a dedicated shielded treatment room where the patient can stay for up to a day.  Because PDR uses a remote controlled afterloader it offers the advantages of radiation safety, prospective planning and precise dose shaping.

Studies have shown that with PDR, short (six to twenty minute), hourly pulses of high dose rate, using the same dose, with same overall treatment time, will virtually simulate LDR1.  At the same time, new afterloading machine technology has become available, where a single, millimetre-sized, Iridium-192radiation source, sequentially moves through the applicator in small individually timed steps.  The advantages are that the radiation dose can be optimised along the applicator with no radiation exposure to staff and no need for patient isolation part from during the pulse. In addition, organs at risk at short distance (‹5 cm) to the target will have significantly less dose with PDR brachytherapy. In conclusion, PDR brachytherapy has dosimetric advantages close to the target compared to EBRT and cannot do more damage to remote organs. Results show a strong indication of equal efficacy between PDR and LDR2.  

Consultant Clinical Oncologist Jacqueline Livsey, The Christie comments, “The ability to see the tumour with apparatus in situ is a big step forward to treatment planning and patient outcome.”

Controlling applicator movement during the delivery time poses a challenge as in order to allow staff to interact with the patient, the PDR equipment typically has a ‘treatment interrupt’ capability which allows the source to automatically be returned to the afterloader while nurses and hospital staff are in the room.

Dr Susan Davidson, Consultant and Honorary Senior Lecturer in Clinical Oncology, at The Christie comments, “The new PDR applicators are a great improvement – they are very intuitive,easy to use and light-weight.”

Nurse Clinician Karen Johnson, The Christie adds “The new PDR applicators are much easier to remove and patients require less analgesia.”

Many treatment centres prefer to use the PDR technique in situations where a LDR equivalent treatment is required as it offers the additional benefit of patient contact. 

Nucletron’smicroSelectron Digital is the latest evolution of the company’s popular afterloader series, with a twenty year reputation for reliability, safety and performance. The ground-breaking software architecture of the new platform combines these qualities with all-in-one versatility and unmatched flexibility that integrates completely into the radiation therapy programme.  It works seamlessly with Nucletron’s Oncentra treatment planning and imaging solutions and is fully compatible with DICOM-based treatment records and plans. Because the functionality is in the software rather than the hardware, it is easy to upgrade from a 6 channel use option for treatments needing only a low number of channels, to an 18 or 30 channel use option.  Andy Clarke, National Sales Manager, Nucletron, comments, “Nucletron is delighted to support The Christie in its pledge to offer cutting edge treatment for its patients.  Thanks to its platform design concept each microSelectron Digital afterloader can be tailored to meet exactly individual needs and easily upgraded with more channels should the need arise. Nucletron has been pleased to provide training to staff at our site in Chester; providing computer-aided training which helps shorten the learning curve of staff.”

1Brenner and Hall published the radiobiology concept for pulsed dose rate (PDR) in 1991

2Bengt Johansson 2010.Long-term outcome research on PDR brachytherapy with focus on breast, base of tongue (BOT) and lip cancer.  Orebro studies in Medicine 42. 81 pp