KW seminar: Radiotherapy Flashcards
What topics can you expect in this lecture?
don’t study obviously
- Numbers
- What is radiation oncology
- Developments
- Future
In 2019, about 151,000 people died. How many died of cancer?
just for indication
46,900. This makes cancer the most common cause of death
(followed by cardiovascular disease, mental disorders and airway diseases)
True/false: The incidence of cancer is stable
False, the incidence is increasing
What were the most common types of cancer in 2019?
- Skin cancer
- Bowel cancer
- Breast cancer
- Lung cancer
- Prostate cancer
What are the 3 cornerstones of treatment in oncology?
Surgery, radiotherapy and medical oncology (like targeted-, chemo- and immunotherapy)
In how many % of the patients is radiotherapy given? In how many % of the patients is the treatment curable?
50% and 50%
How does radiotherapy work?
Ionizing radiation is given to the patient (photons, elektrons and protons). This radiation will cause free radicals which damage the DNA. Healthy cells are able to repair this damage, but malignant cells will not, and thus die
What does this figure show?
This shows a dose-response curve of tumors treated with radiotherapy. If you look at the vertical red line, you see that at that dose 100% of the tumor (blue line) will react, and less than 20% of healthy cells are damaged. You can imagine that if a tumor is more sensitive, this curve will go to the left since you need a fewer dosis
What machine is used for radiotherapy?
A medical linear accelerator.
It delivers high-energy x-rays or electrons to the region of the patient’s tumor. These treatments can be designed in such a way that they destroy the cancer cells while sparing the surrounding normal tissue.
What are the clinical steps during a radiotherapy treatment?
- Consult with radiotherapeut-oncologist: explaining the treatment to the patient, physical examination
- Preparation: imaging is done to determine the target volume (with CT-scan)
- Planning: a personal treatment-plan, which is made in a several days with multiple doctors
-
Radiotherapy: for a certain amount of time, during a certain period, the patient undergoes therapy
- Verification: extra screening is done to determine if the treatment is on the correct spot and if it’s working
- Aftercare: check-ups after the treatment
What did the treatment plan for radiotherapy look like in the past? (before the invention of CT-scan e.d.)
An X-ray was used, which gives a 2D-view, generous margins were used, large fields were irradiated, fractionated and long scheme was used (30+ appointments)
What are complications of radiotherapy (especially in head- and neck cancers)?
!!! trigger warning, sensitive images on the next slide !!!
- Dermatitis
- Mucositis
- Dry mouth (xerostomia)
- Osteoradionecrosis
Another novel technique that is used in the clinic is Intensity modulated radiotherapy (IMRT). How does this IMRT work and what other technique is needed to use this?
Intensity-modulated radiation therapy (IMRT) is an advanced mode of high-precision radiotherapy that uses computer-controlled linear accelerators to deliver precise radiation doses to a malignant tumor or specific areas within the tumor. IMRT allows for the radiation dose to conform more precisely to the three-dimensional (3-D) shape of the tumor by modulating—or controlling—the intensity of the radiation beam in multiple small volumes. IMRT also allows higher radiation doses to be focused on the tumor while minimizing the dose to surrounding normal critical structures. Treatment is carefully planned by using 3-D computed tomography (CT) or magnetic resonance (MRI) images of the patient in conjunction with computerized dose calculations to determine the dose intensity pattern that will best conform to the tumor shape.
How does a scan of a 3D radiotherapy CT scan look?
For illustration
Besides the development from 2D to 3D imaging, radiotherapy also changed from conventional radiotherapy to stereotactic radiotherapy in lung cancer. What does this mean?
That the tumor is targeted from multiple angles, instead of just from the front/back. A smaller volume is needed and a higher precision is achieved. This means that a higher dose can be given and a shorter scheme is possible (no 30 appointments anymore)
What is magnetic resonance (MR)-guided radiotherapy?
The combination of magnetic resonance imaging and radiation therapy technologies, leading to improved soft-tissue visualisation, assessment of inter- and intrafraction motion, motion management, online adaptive radiation therapy and the incorporation of functional information into treatment.
As you can see in the figure, a tumor is pointed out. During irridation of the tumor however, the patient breathes which can change the position of the tumor. With the use of MR-guided radiotherapy, this change is ‘seen’ and the irridation is stopped in that area so no healthy tissues are damaged
A very new idea is to use protons instead of photons (X-rays) during the treatment. Why would this be better?
X-rays have the highest dose between 2-4cm into the body surface, and also stays longer active into the body (green line). However, proton beams are much more efficient, in the fact that they have a peak at the same surface as the tumor, and do not penetrate the body much deeper than that (blue line). However, there are down-sides to this method which the lecturer did not discuss due to lack of time and it also has to be tested further in the clinic before it can be used
As you can see in this image, protons are not as precise as IMRT, but it is much more precise than 3D conformatl radiotherapy
Nice
Has the 5-year survival rate increased due to the developments in radiotherapy?
Yes, from ~47% to ~62%
This graph is the result of ALL cancer treatments, not all
