Radiation Therapy Now Available in Victoria

In fact – it’s always been available!

In 2006, Southpaws established the first dedicated deep-therapy radiation unit for animals in Australia. While it is not the most advanced form of radiation therapy, the orthovoltage unit at Southpaws is the same type of radiation therapy currently in use in 28 human facilities across Australia. We have treated hundreds of animals with generally excellent clinical results and acceptable side-effects.

Dedicated veterinary linear accelerators at centres in Sydney and Brisbane are amazing pieces of equipment. If we had a linear accelerator at Southpaws, we would use it preferentially over our orthovoltage machine in most cases.

Out-of-state linear accelerators offer significant advantages over Southpaws’ orthovoltage machine. These include:

• Significantly greater depth of penetration. Treatment of tumours more than 20 cm deep is possible and much larger tumour volumes can be treated.
• Computerised modelling with linear accelerators, not possible with orthovoltage, allows precise treatment of deep tumours including those in the brain, thoracic and abdominal cavities. Precision allows avoidance of normal surrounding tissues, reducing side-effects with deeper protocols.
• No increased absorption by bone. Our orthovoltage machine selectively delivers 12% more radiation to bone than to surrounding soft tissue, theoretically increasing the risk of late side effects. Note that we have NEVER seen bone necrosis in hundreds of patients treated in our facility.
• Many linear accelerators have built-in CT scanners and other types of imaging offering more repeatable dosing particularly with deeper protocols.

Note that when treating superficial areas, linear accelerators offer relatively little advantage compared with orthovoltage radiation therapy. This is why orthovoltage continues to be used in human cancer centres despite having access to linear accelerators.

• Cost of treatment. Palliative orthovoltage protocols at Southpaws costs about $4,000 in total and curative intent protocols cost around $5,000-$7,000. This is in contrast to protocols performed out-of-state which range from $12,000 to $16,000 dollars.
  The reason for this cost differential is that linear accelerators can cost millions of dollars. In addition, the fit out can also cost more than a million dollars. The linear accelerator at Monash Medical Centre has four meters of high-density concrete in front of the primary radiation beam. Quality control physics can cost $100,000 per year. Usually, a specialist radiation oncologist must be employed. The high cost of linear accelerator radiation therapy is justified, but it is cost-prohibitive for many clients.
• Selective bone resorption offers an advantage of orthovoltage when treating appendicular osteosarcoma and other bone cancers.

Interstate travel is required and protocols can last up to six weeks.

• Orthovoltage radiation therapy is ideal for superficial treatment of tumours and incomplete surgical margins which require less than 3cm depth of penetration.
• Palliative treatment of oral melanoma is associated with a median survival time of nine months.
• We have treated dozens of dogs and cats with intranasal tumours. When combined with surgery at Southpaws, we have reported a median survival time of 26 months in dogs with intranasal tumours. This is far greater than the results reported with linear accelerator radiation therapy alone.
• We have also treated dozens of patients with appendicular osteosarcoma with good results. We are in the process of publishing the treatment of canine osteosarcoma with radiation therapy and chemotherapy and are reporting a median survival time of seven to ten months. We prefer to treat tumours of the distal extremities (distal radius and ulna, distal femur and proximal tibia), and of the mandible. We struggle to get adequate penetration of tumours in the proximal humerus, maxilla, spine, pelvis and ribs.

• Brain tumours are MUCH better treated with linear accelerators. We won’t treat brain tumours with radiation at Southpaws except in very specific circumstances.
• Anything involving the abdomen or thorax is exclusively the domain of a linear accelerator. We will not treat intraabdominal or intrathoracic tumours, except occasionally with intraoperative radiation therapy where we can physically exclude vital and vulnerable structures. We prefer not to treat tumours of the thoracic and abdominal wall because of damage to underlying structures including the lungs and the gastrointestinal system.
• Anything requiring a treatment depth of greater than 3cm. The exception to this is intra-nasal tumours, which we are happy to treat and have had outstanding results with orthovoltage radiation. We are also happy to treat extremity osteosarcoma because we can achieve adequate penetration when coming in from bilaterally opposed treatment beams.

Southpaws will always make the most appropriate recommendation for the treatment of unresectable tumours and incomplete surgical margins. Initial radiation therapy consultations are free. We have a great relationship with the out-of-state linear accelerator facilities and are very happy to refer patients when appropriate, as we have done with many of our own patients.

Let Southpaws be your first stop when considering radiation therapy for the treatment of our companion animals with cancer. We will discuss all treatment options and make the most appropriate recommendation for your patient.