radiotherapy Flashcards
what is radiotherapy
high en radiation to damage dna and ultimately kill cells
does of radiotherapy is measured in..
grays
what does Gy represent ?
am of en deposited in tissue
types of internal radiography
- radioactive isotopes
- brachytherapy
radioactive isotopes ..uses & how
- unsealed radioactive sources to treat systemically
- A radioactive isotope is given and taken up by the target organ
brachytherapy … uses
sealed radioactive sources in or close to the area to be treated, or directly into tumour
external beam radiotherapy (EBRT)
eg linear accelerators
invisible beam gives dose
patient pathway of radiotherapy
pre-planning positioning & immobilisation localisation treatment planning verification treatment
pre-planning (consultation)
consent form
treatment request form
treatment planning decisions on..
what to treat(targeted volume TV) or not (OAR)
what prescription
Treatments are prescribed by the Radiation Oncologist
in this format
Total Dose /no. of Fraction/ Duration
eg 50 Gys/ 25 hastag / 5 weeks
when is Dose and Fractionation decided
at planning stage - prescription
standard dose
2 gy per fraction
HOWEVER higher dose per fraction over a shorter period sometimes
total dose determinded by
the tumour and tolerance of critical normal tissues
fractionation schedules -hypofractionation
-Reduced total dose
– Size of the dose per fraction increased
– No. of #s decreased
– Overall time varies
opposite= hyperfractionation
hyperfractionation
radiation treatment where total dose of radiation delivered is divided into smaller doses and treatments are given more than once a day (typically 2-3 a day)
What factors will influence the side effects a patient receives from a treatment? pt1
-Anatomical Site(Type of tissue)
• Energy and type of radiation used
• Total Dose given
• Dose per Fraction / Treatment Time
What factors will influence the side effects a patient receives from a treatment? pt2
-Treatment Planning
• Total Volume irradiated– Volume of normal tissue irradiated
• Tolerance Doses –Dose volume constraint (DVC’s)
consequential late effects
non healing acute reaction become permanent
sub acute toxicity
- time line
- why
- effects
- symptoms
- treated by
- 6wks —6mths
- Cells that turn over more slowly eg lung
- Acute inflammation and Radiation Pneumonitis
- shortness of breath fever cough
- steriods
types of toxicity scoring systems
- EORTC/ RTOG
- CTC AE
- LENT /SOMA
EORTC/ RTOG
stands for..
used when..
- European Organization for Research and Treatment of Cancer /Radiation Therapy Oncology Group
- acute and late setting
EORTC/ RTOG scale
0-5
0=no symptoms
5=death directly related to radiation effects
CTC AE stands for
common terminology criteria for adverse events
CTC AE grades
grade 1=asymptomatic/mild symptoms 2=moderate 3=Severe or medically significant ... not lifethreating 4=Life-threatening 5=death
LENT /SOMA stands for
- Late Effects Normal Tissues
- Subjective / Objective / Management / Analytic
LENT /SOMA stages
1-4
LENT /SOMA levels of severity
–Occasional = monthly
– Intermittently= weekly
– Persistent = daily
– Refractory = constant
what do we use for acute effects
EORTC/RTOG or CTC AE version 5
what do we use for late effects
EORTC/RTOG or LENT/SOMA or CTC AE version 5
acute side effect
effects during treatment…. Toxicity that manifests itself within days or weeks of starting treament … up to 90 days after completion
late side effects
months or years after treatment
why hypofractionate
- reduces the chances of the cancer cells to repopulate
- more convient for patient
for verfication we take a
CBCT(cone beam computed tomography) this is where you take an image after positioning and immobilizing the patient.
3D scan that you will match to the CT that you took at the planning stage to verify that the patient is in correct position and you will be treating the target
localisation
Treatment position
is patient supine or prone
