Radiation Therapy Planning and Treatment for Breast Cancer
By Ms Adeline Lim

Adeline is a Senior Radiation Therapist at the Radiation Oncology Department, RAH Cancer Centre, Royal Adelaide Hospital, South Australia. At Radiology Malaysia’s request, she has attempted to take away the mystery of radiation therapy and at the same time, shares her experience at the place where she works. We wish to thank her and the Royal Adelaide Hospital, South Australia for consenting to write on this topic.  The RAH Cancer Centre is one of the leading cancer management centres in the world.

Topics Covered:

• Definition of Radiation Therapist
• Introduction
• Before Starting Actual Treatment – Planning Stage
• The Patient Can Now Start Radiation Treatment – Treatment Delivery, Treatment Techniques, Clinical Reviews
• After the Treatment – Follow up for 15 years
• Side Effects of Radiation Therapy – Acute and late
• Quality Assurance at the Royal Adelaide Hospital

Definition of Radiation Therapist

A Radiation Therapist is a key member of the oncology management team, who in conjunction with the Radiation Oncologist (a medical doctor who specialises in radiation treatment in cancers) is responsible for the accurate dose calculation and delivery of the prescribed radiation dose, specific to the patient’s cancer site.  Radiation Therapists play a vital role in the development of new techniques, evaluate and advise on equipment, research and education of students, allied health staff, patients and the public in the radiation therapy of cancer.  The Radiation therapist is trained to understand and address the physiological and psychological responses of the cancer patient to minimise the emotional and physical impact of the radiation treatment.
 

Introduction to Radiation Therapy Planning and Treatment

Radiation Therapy or Radiotherapy is one of the main treatment options for breast cancers. Statistics have shown a decrease in local recurrence from 40% to 15% with radiation therapy following breast conservative surgery. When patients are told that they require radiation therapy, the following questions are often asked. What is radiation therapy? How is the treatment given? Is it painful? What are the side effects? Why can’t I start the treatment immediately? Am I getting the correct treatment? This article provides some of these answers and help to reassure the patients. They often misunderstand planning time to be ‘waiting list’, especially in a public hospital and worry it may affect the cure. This will reduce their stress and anxieties.

Radiation Therapy uses ionising radiation (high-energy x-rays, gamma rays and electron beams) to kill cancer cells. For many cancers, Radiation Therapy is the treatment for cure that can be enhanced with surgery and chemotherapy. It is used to relieve symptoms such as pain, breathing difficulties and bleeding caused by advance staged cancers.
 

Before The Actual Radiation Therapy – Time Needed for Planning the Treatment

Before a patient can start radiotherapy, the treatment has to be planned.  This is to determine the treatment position, the tumour volume and computer dosimetry that will accurately deliver the radiation dose to the cancer with minimal damage to the adjacent healthy tissues.  The planning steps are:

a)  A Planning C-T (computed tomography) appointment that involves establishing the patient’s treatment position on a special breast board (Fig 1) that can be reproduced over the entire course of the radiotherapy.  C-T scanning (Fig 2) is done to acquire the patient’s skin contour, tumour volume, lung, heart and adjacent healthy tissues for computer dosimetry.  Often the patient may be given 2 pinpricks or tattoos for alignment to ensure the same daily treatment position. (Fig 3). 

In our Cancer Centre, the procedure is done by a team made up of a Radiation Oncologist (or also known as the Radiotherapist) Consultant and Registrar and two Radiation Therapists. The time for this procedure is about 30 minutes.  The patient can then go home, with a starting date that varies from 3 days to a week depending on the workload of the department.  Patients need to be reassured that this ‘waiting’ time does not affect the cure.  This planning time is vital for best outcomes because human errors can occur when work is rushed through.

b)  The required data from the C-T scan is used for computer dosimetry.  The Radiation

Oncologist draws a margin round the tumour volume and the Radiation Therapist proceeds to plan the dose distribution on a 3-D radiotherapy computer system.  The finished computer plan is shown to the Radiation Oncologist for approval. The data from the computer plan such as the treatment photon (X-ray) energy, the field size, the beam angles and daily dose are documented into a folder for the Radiation Therapists on the treatment machines for the daily patient treatments.  This document has to be checked by a Senior Radiation Therapist before it can be released for treatment.  This whole planning process does take time to ensure accurate and quality treatment.  The patient can now start treatment.
 

The Patient Can Now Start Radiation Treatment

Figure 4

Treatment Delivery
The treatment is given on state-of-the-art equipment called a Linear Accelerator (Fig 4) that has:

1. Skin-sparing effect where the 100% dose is a least 1.0 cm. beneath the skin surface.  This enables a greater tumour dose to be given with minimal skin reactions

2. Isocentric Mounting designed for accurate and efficient beam positioning

3. Multileaf Collimators that allow accurate matching of adjacent treatment sites and conforming to the irregular tumour volumes

4. Electron Beams to treat superficial tumours or surgical scars

5. Electronic Portal Imaging device that captures the real time treatment.

The treatment is delivered by a team of 2 Radiation Therapists who have to:

• Reproduce the documented position

• Watch out for changing shape that may require replanning

• Crosscheck the set–up details (field size and centers, beam angles and dose) before switching on the machine.

• Monitor patient’s condition and side effects that require medical attention

• Attend to the psychosocial needs with effective communication, people skills and moral support.

Treatment Techniques

For Chestwall/Breast only, a pair of tangential fields (Fig 5) is used to avoid the lung and underlying healthy tissues.  This treatment takes about 10 minutes to reproduce the set-up and for the 2 beam times of about 1 minute each.  The treatment is not painful and the patient does not feel it.  It is similar to having an X-ray.   The patient needs to be comfortably relaxed from initial setting up to during treatment to minimise movement. (Fig 6)

Figure 7 - A third field to treat the supraclavicular nodes ismatched to the breast volume fields

Figure 8 - A Radiation Therapist fixing the electron applicator to the Linear Accelerator for the ‘’Boost’’

For Breast, supraclavicular and axillary nodes, an additional field is matched to the tangential fields.  The beam is directed from the top to the rectangular field.  This 3-field technique takes about 15 minutes.  (Fig 7)

‘’Boost’’ or additional dose is sometimes given to the surgical scar or primary tumour site to ensure maximum tumourcidal dose is achieved.  A direct electron beam is used where a special applicator is brought close to the localised area for about 1 minute.  (Fig 8)

Clinical Reviews
The patient is reviewed at least once a week in the Clinic by the Radiation Oncologist to assess progress, side effects and early detection of disease spread.
 

After the Radiation Treatment

Follow Up Appointments for 15 years
On completion of the treatment, the patient is assessed initially at 2 to 3 weeks after the last treatment and at longer intervals depending on the status.  This is to monitor side effects, response, recurrence or metastasis.  The family must encourage the patient to attend for early detection of disease spread to ensure effective treatment.
 

Side Effects

A   Acute
a) Systemic (where the whole body is affected) – lethargy and psycho emotional

b) Local (at the region of where the radiation was delivered)
skin and subcutaneous tissues: erythema (redness of skin) and desquamation (flaking/peeling of skin);oedema of upper limb (swelling of the upper limb due to retention of lymphatic fluid) & breast pain and axillary hair loss

B  Late
Pain (breast, muscle and rib), pulmonary fibrosis, pneumonitis, pigmentation, oedema and brachial plexopathy (the latter effects are due to the radiation “killing” some normal cells and also causing inflammation)
 

Quality Assurance undertaken at the Royal Adelaide Hospital, Adelaide, South Australia

Quality assurance is part and parcel of any Radiation Therapy Unit. Here I present our programme and our experience with implementing Quality Assurance in the Royal Adelaide Hospital.

1. Multidisciplinary approach by Radiation, Medical and Surgical Oncologists, Pathologists and Radiologists to discuss the best management for all referred patients at a weekly Breast Clinic.

2. Team Approach by the Radiation Oncologists and the Radiation Therapists.  The technique and dose prescription for each patient is peer reviewed and discussed at a weekly ‘‘Chart Round’’ meeting.

3. A strict code of work practices in the planning and treatment e.g.

• Treatment documents must be checked by a Senior Radiation Therapist and have 2 signatures before they can be released for treatments

• The first treatment is supervised by a Senior Radiation Therapist

• Each treatment is delivered by a team of minimum 2 Radiation Therapists to ensure accuracy and correct treatment set-ups.  A second staff checks the monitor units or time before the machine can be switched on.  The given treatment is documented and countersigned.

• An X-ray film or an electronic image is taken to verify the accuracy of the treatment delivered

4. Best practice demanded of the staff in a Teaching Hospital to meet the expectations of the public and to inculcate this practice in our undergraduates.

Studies have shown the above Quality Assurance protocol does enhance the cure rates.  I am proud to add that recent statistics show that South Australia has one of the best cancer management in the world.
 

References

• Breast Cancer Seminar, Royal Adelaide Hospital, 5^th December 1998

• Radiotherapy & Oncology 46(1998) 99-103

• Radiation Oncology Dept.’s Protocol @ Royal Adelaide Hospital, S. Australia

• Griffiths S. & Short C.(1994) Radiotherapy: Principles to Practice, Churchill Livingstone, London

• Bomford C.K. et al (1993) Walter and Miller’s Textbook of Radiotherapy, Churchill Livingstone, London

• Bentel, G.C.(1992) Radiation Therapy Planning Macmillan Pub. Co., USA.

• Med-Tec Radiation Therapy Sourcebook (1997-1998)

Know your facts!

Some people get confused between radiotherapy and radiographs in
Radiology (or x-rays as
it is commonly called). The radiation doses received in radiation therapy is very different from those received in diagnostic radiology –
the “xray” examinations that you may be familiar with. While radiation in radiotherapy is intended to kill cancer cells, every attempt is made in diagnostic radiology to minimise radiation as
far as possible and only just enough is used to give a good diagnostic quality radiograph (x-ray). Even in radiation therapy, planning is
vital to ensure only the correct and necessary dose to the correct area
is given. All properly trained personnel
working with ionising radiation use their procedures/tools with
care and responsibility.
- Editor