Introduction to Radiation Therapy Jen Dewhurst MRT(T)

AGENDA Treatment Options and Goals What is Radiation? Steps involved with Radiation Therapy The format of our presentation today…

Treatment of Cancer Surgery - Cut it out Chemotherapy – Through whole body Radiation – On targeted area It has been known for over 2000 years that there are 3 ways to treat cancer: To cut it off (surgery) To use caustic herbs (chemotherapy) To burn it off (originally this was meant to apply to cautery but has evolved into radiation therapy) X-rays were discovered in 1895 by Wilhelm Roentgen About 50% of patients will have radiation therapy at some point in their illness, often together with chemo and surgery.

The Primary Goal of Radiation Therapy To treat the tumour to the highest dose possible while minimising the effects on normal tissues It’s worth a look at the primary goal of radiation therapy; that is:

Other Goals of Treatment Cure eradicate cancer and live a normal life span ‘radical’ course of radiation, more # of treatments Control control growth or spread of cancer; live for a time without symptoms longer course Palliation relieve or diminish symptoms; improve quality of life a short course of XRT, small # of treatments Prophylactic or anticipatory prevention of complications or symptoms

Radical Radiation Therapy Aiming for long term survival Higher doses and longer treatments Typical sites: Breast Prostate Lung Head and neck Cervix or uterus Radical treatment is aiming at long term survival so the treatments are longer and the side effects more severe. The most common sites are breast and prostate. The treatment times for breast are 5 weeks, for prostate 6 or 7 weeks.

Palliative Radiation Therapy To provide symptom relief Low doses and shorter treatments Typical treatments: painful bone metastases cough or bleeding from lung tumours airway compression 50% of radiation therapy patients are for palliative treatment. Treatments are shorter, we may give only 1 treatment of 800 cGy. Sometimes patients present as an emergency. The most common emergency is spinal cord compression caused by vertebral collapse due to bone metastases. In an emergency situation we would want to start the patients treatment within 24 hours.

AGENDA Treatment Options and Goals What is Radiation? Steps involved with Radiation Therapy The format of our presentation today…

What is Radiation?? Radiation is a form of ENERGY Includes everything from X-rays, to light we can see and to radio waves. All radiation travels at the same speed (the speed of light) but has a different energy according to the electromagnetic spectrum. Naturally occuring elements or man-made energy

The Electromagnetic Spectrum -Radiation is a form of energy -includes everything from X-rays, to light we can see and to radio waves. -All radiation travels at the same speed (the speed of light) but has a different energy according to the electromagnetic spectrum.

How Does Radiation Therapy Work?

Radiation Effects on Cells Radiation damages ALL cells – healthy and diseased. This causes side effects – but ONLY in the area we are treating Healthy cells can repair themselves while diseased cells die off NEW…

What is Radiation Therapy? Application of ionizing radiation to shrink and kill cancer cells, and to prevent them from multiplying Radiation Therapists are the only specialized members of the Health Care team who are trained, and authorized to deliver this treatment. Radiation Therapists are also trained to work with the Radiation Oncologists to plan treatments, to do the calculations, and to deliver the treatment accurately.

AGENDA Treatment Options and Goals What is Radiation? Steps involved with Radiation Therapy The format of our presentation today…

Simulation/Planning 1st visit to DRCC - Radiation Therapy Department CT Scan Tattoos Immobilization Planning after the pt leaves (Few hours – Several weeks)

Simulation / Planning CT Scanners are used to localize the treatment volume as per the prescription. These machines are exactly the same as diagnostics scanners with a few minor changes; the addition of external laser positioning systems, and a flat table top.

CT SIMULATION Position pt (reproducibility, immobilization, accessories) Operate CT machine Place isocenter Tattoo Documentation

TREATMENT PLANNING (http://www.lumc.nl/1010/LKEBHome/english/ research/OnP/Radiotherapy/DRR.gif) Individual tx plan – optimize how to deliver the highest dose with the minimum s/e Once the patient data has been gathered at the simulator session, this information must then be changed in to a treatment plan. Specific computers called Radiation Treatment planning systems are used to calculate the treatment field sizes and length of time each treatment will take. And a gain we’ll look at this in a little more detail when I talk about the patients treatment journey at the Durham Regional Cancer Centre. There is a lot of data gathered from the CT. This data is then transferred to the treatment planning system. The information is basically in the form of CT slices. On each of the individual slices the radiation oncologist will contour the tumour volume. The normal structures around the tumour are then contoured either by the oncologist or the dosimetrist (treatment planner). Once all the contouring is complete then the treatment fields can be added to the treatment plan. These fields are placed to cover the tumour but minimising the normal tissue included. (http://varian.mediaroom.com/file.php/141/Dose+distrib+IMRT+prostate.jpg Copyright ©2007, Varian Medical Systems, Inc. All rights reserved)

DOSIMETRY GUIDELINES Typical prescribed doses: Breast 5000cGy in 25 treatments Prostate 7000cGy in 35 treatments Palliative 2000cGy in 5 treatments Typical dose limitations: Cord <40Gy max. Rectum v60 < 40% The unit we use in radiation therapy is the Gray. It is a measurement of absorbed dose – the energy deposited by ionizing radiation in a specific mass of tissue. When radiation oncologists prescribe treatments, they use established doses that are based on clinical trials and years of cumulative experience. We also choose an energy depending on what we need to treat - higher the energy of the radiation, the deeper it can penetrate. This means that if we are irradiating something large, like an average sized pelvis we need a higher energy than, say, a thinner body part such as an arm or a neck. Our machine has different energies so when we’re planning a patient’s treatment the first thing we look at is “how big is the area we are treating” or “which machine would be best for this patient”? doses are based on the most we can give the tumour while minimising dose to the surrounding normal tissues. We can rarely just treat the tumour. This is why radiation therapy carries side effects. ****next pic Let’s look at a typical treatment to the prostate, the rectum and bladder are very close to the prostate. The dose is limited because serious side effects such as fistulas or bladder fibrosis.

Treatment Linear Accelerators are the standard treatment machine Electrically produce beams of x-rays which are shaped (collimated) to the precise size and energy required for treatment. Machines can rotate 360 degrees around a patient to deliver treatment from any angle. These ‘Linacs’ also take x-ray images of the patient for verification purposes.

FIELD VERIFICATION Therapists on the treatment unit use cone beam for 3-D image matching Every day a CB is taken and compared with the original data set captured during simulation The tolerance is 3 mm, so if the displacement is > 2 mm then the pt is moved into the correct position If the seeds are off by 6 mm or more than the CB is repeated

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