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About radiation therapy

1. What is radiation therapy what is the treatment process?

Radiotherapy is one of the methods to treat cancer with the use of ionizing radiation. Ionizing radiation is also used in imaging techniques such as X-ray or computed tomography, while in radiotherapy we use radiation doses high enough to damage the cellular DNA structures of cancer cells. Radiation therapy is a local treatment and due to the new and improved technology it is possible to deliver high doses of radiation to the tumor while sparing healthy surrounding tissues. Radiation therapy is currently one of the most dynamically developing areas of veterinary medicine. The unit describing the amount of energy delivered to the tissues in radiotherapy is called Gy (gray).

2. What is the difference between megavoltage and orthovoltage radiotherapy?

Megavoltage radiotherapy is characterized by much higher radiation energy compared to orthovoltage radiotherapy. As a result, megavoltage radiotherapy has a much greater penetration and allows irradiation of lesions located deep in the patient’s body. Orthovoltage radiotherapy can only treat superficial lesions, such as non-advanced skin cancers. Megavoltage radiation is less absorbed by bone tissue, and thus the risk of osteonecrosis or secondary bone cancer, well documented with orthovolt radiotherapy, is much lower. Treatment with high energy photons, unlike orthovolt therapy, has a “skin-sparing” effect, so the risk of burns is much lower. For this reason, the treatment of skin lesions with megavoltage radiotherapy also requires the addition of a bolus. In general, megavoltage radiotherapy is characterized by better treatment tolerance (fewer side effects).

3. Indications for radiation therapy

  • Brain and spinal cord tumours
  • Nasal cavity and nasal planum tumours
  • Soft tissue sarcoma, injection site sarcoma
  • Oral tumours
  • Head and neck cancer
  • Mast cell tumours
  • Urinary bladder and prostate cancer
  • Metastatic anal sac adenocarcinoma
  • Bone cancer 
  • Others

4. What are the stages of the radiotherapy treatment process?

The total dose during radiotherapy is divided into so-called fractions. This is due to several reasons. This not only enables a higher total dose to be delivered to the tumor lesion, but also minimizes side effects affecting healthy tissue in its immediate proximity.

In order to plan radiotherapy, it is necessary to perform an imaging examination using computed tomography (CT) at the RTWet centre. Based on the images obtained, it is possible to “contour” the tumor and plan the radiation therapy. It also allows us to assess which tissues will be in the irradiation field and therefore predict/modify side effects. The examination must be performed in the center offering the treatment due to the patient’s positioning in the so-called therapeutic position, i.e. the position in which the patient will then be placed for radiotherapy. If, prior to being referred to the centre, a CT or MRI examination has already been performed, please provide a CD with the full study, as these images are often “overlaid” on the images of the examination performed at the centre, which additionally facilitates precise treatment planning.

A CT scan to plan radiotherapy, like all radiation therapy sessions, is performed under superficial general anesthesia, from which the patient usually wakes up quickly. Anesthesia for radiotherapy planning takes about 3 hours, including premedication and recovery. Currently, 4 anesthesiologists provide anesthesiological care for the patients of the centre. Planning radiotherapy takes from a few to several hours, depending on the complexity. We usually arrange the start of treatment a few days after the imaging examination.

5. How long does radiotherapy treatment take?

The radiotherapy plan is adapted each time individually to the clinical situation of a given patient.  Patients usually receive 4 to 20 fractions of radiation from once a week, every few days or every day.

The number of radiotherapy fractions depends on the type of cancer, its location and the purpose of treatment. The least intensive palliative protocols contain 4-6 treatment fractions, and the protocols with the largest number of fractions (20) are often recommended for tumours affecting the central nervous system. Administration of one radiation therapy fraction takes only a few minutes, while placing the patient on a special table, in exactly the same position may take 15-30 minutes. The treatment takes place from Monday to Friday, which means that with 20 fractions of irradiation, the treatment will take 4 weeks.

6. Referring a patient for radiation therapy

A referral process should be started by filling in the form available on our website. Ideally, the form should be completed by the referring veterinarian but this is not always possible and the application can be completed by the pet owner. Please provide as much detail as possible. Please attach:

  • Medical history (all previous records from the vets who saw the patient)
  • Blood and urine tests done in the last year
  • DICOM imaging studies and radiologist report
  • Cytological and histopathological examinations
  • Treatment history
  • Photos of neoplastic lesions/scars

Please ensure that all attachments are in the chronological order and labelled accordingly.

After submitting the referral form, one of our oncologists checks all the attached results and within 3 working days we offer a consultation if suitable. Most consultations take place at the RTWet center in Miedniewice, but in exceptional situations we also offer online consultations. During the consultation, we discuss the treatment process, expected side effects, and sometimes we also order additional tests. The next step is to schedule a CT scan for radiation therapy planning.

Form for the owner

7. What is the process of consultation qualifying for radiotherapy treatment?

The consultation usually takes place at the RTWet Center in Miedniewice. During the qualifying consultation, one of our oncologists discusses the patient’s treatment history with the pet owner. After the clinical examination, treatment options are discussed. After consultation, patient is scheduled for a CT scan and radiotherapy planning. This is done within a few days of the consultation, and in some cases (by prior arrangement) we offer same-day radiotherapy planning.

8. What to bring with for the first consultation?

Please bring all the medical records and imaging studies recorded on CD if possible.

List of items to take for the first consultation

9. How to prepare a pet to receive the first dose of radiation therapy?

Every patient needs to be fasted. For dogs, it is 8 hours with no food, for cats 6 hours.

Water is allowed at all times.

10.Veterinary care outside the centre working hours

Our center offers radiation therapy only. Treatment is ambulatory, which means we don’t provide emergency care 24/7. Therefore, we are not in a position to offer treatment for patients that are unstable, requiring intensive care. In case of emergency outside our working hours, we refer to nearby clinics providing 24/7 care.

11. Accomodation at the centre

We offer accomodation for pet owners while their pet is receiving radiation therapy treatment.