Introduction to Radiotherapy Flashcards
A medical specialist certified in the
practice of radiation oncology in
the Philippine Board of Radiation
Oncology and is at least responsible for consultations, dose prescriptions, on-treatment supervision and evaluations,
treatment summary reports, follow-up monitoring and evaluation of treatment outcome
and morbidity.
Radiation Oncologists
An individual who has PhD or
Masters Degree in Medical Physics
with the appropriate clinical
training in radiation oncology
medical physics.
Medical Physicist
Performs Dosimetry works,
calibration, and design treatment
plans by means of computer or
manual computation of radiation
doses.
Medical Physicist
performs Dosimetry works, calibration, and design treatment plans by means of computer or manual computation of radiation doses
Medical Physicist
A _____ duly licensed by the PRC, who is
practicing radiotherapy technology
and is responsible for operating
simulators, computed tomography
(CT) scanners, treatment units etc;
for accurate patient set-up and
delivery of a planned course of
radiation therapy prescribed by a
radiation oncologist; and for
documentation of treatment.
radiologic technologist
Radiation Therapy team
RADIATION ONCOLOGISTS
MEDICAL PHYSICIST
RADIOTHERAPY TECHNOLOGIST
ONCOLOGY NURSE
is performed by a group of team members, including the radiation oncologist, radiation physicist,
radiotherapist, dosimetrist, nurse, psychologist, and/or social workers.
Radiotherapy
The treatment success in radiotherapy is _____ on adequate technical equipment.
highly dependent
the first step in radiotherapy
simulation
is radiotherapy field determination using a diagnostic X-ray machine with similar physical and geometrical features to the actual teletherapy machine.
Simulation
The simulation can be performed by ____, or rarely by ____
CT, MRI
PET–CT
The simulation performed by a
_____ is a real- time simulation procedure, since it is done directly in the patient.
the simulation performed
by a ____ is a virtual simulation
since the tumor is localized
digitally.
BASIC STEPS OF RADIOTHERAPY PROCEDURE
Immobilization
Imaging
Tumor Localization
Treatment Planning
Set-up
Treatment
Quality Control
desired SSD value is usually
80–100 cm
Parameters that Should Be Written on the Simulation Film:
Simulation date
Field size
Gantry angle
Collimator angle
Depth
Magnification factor
Physician name
Technician name
SSD
SAD
Patient position
Right and left signs
Reference points are determined
by _____ located at the cross-sections of the lasers
radiopaque markers
three reference points for CT Simulation:
craniocaudal
right and left lateral sides
The region of interest (that for
which serial CT slices are to be
taken) is determined by the
radiation oncologist
The patient should then rest for ____ after CT to check for any possible adverse reactions.
20 min
defined as visible tumor volume in images
GTV: gross tumor volume
defined as GTV + subclinical/invisible invasion
CTV: clinical target volume
defined as CTV + IM (internal margin for organ motion)
ITV: internal target volume
defined as ITV + SM (setup margin for setup error)
PTV: planning target volume
Conventional Simulation Steps
Immobilization
Patient Positioning
Imaging and tumor localization
Various types of apparatus are used for immobilization. The most frequently used apparatus is the
thermoplastic mask
are predetermined locations for each region of the body.
Reference points
The ____ has published many
reports that are used to determine treatment parameters and define target volumes so that radiotherapy can be accurately planned.
International Commission on Radiation Units and Measurements (ICRU)
The International Commission on Radiation Units and Measurements (ICRU) has published many reports including
•ICRU 50 and 62 on photon ener-
gies of external treatments
•ICRU 71 on electron energies
•ICRU 38 (1985), ICRU 58 (1958),
and ICRU 72 (2004) on brachytherapy treatment
•ICRU 78 on proton therapy in 2007
The _____ reports define the target volumes and organs at risk.
ICRU 50 and 62
• is the macroscopic volume of the tumor
• defines the tumor volume determined by clinical exam and imaging modalities (visible, palpable).
gross tumor volume (GTV)
Visible or palpable tumor volume, clinical volume
GTV
The _____ encompasses the possible regions into which the microscopic disease may extend, or regions with a high risk of involvement based on clinical experience (invisible tumor).
clinical target volume (CTV)
• Subclinical volume and clinical volume
clinical target volume (CTV)
The ____ defines the volume formed when the CTV is extended due to
physiological organ movements or technical reasons.
planning target volume (PTV)
The ____ is the volume, including the reference isodose, that has the minimum probability of incurring complications.
treatment volume (TV)
is the volume that receives a significant dose, based on normal tissue tolerance doses.
irradiated volume (IV)
Volume Definitions According
to ICRU 50
GTV
CTV
PTV
TV
IV
Volume Definitions According
to ICRU 62
•internal target volume (ITV)
•planning organs at risk volume (PRV)
•Internal margin (IM)
•setup margin (SM)
•organ at risk (OAR)
•conformity index (CI)
In addition to the volumes defined by the ICRU 50 report, two new volumes termed the ____ were added.
•internal target volume (ITV)
•planning organs at risk volume (PRV)
defines physiological organ movements.
internal margin (IM)
defines movements relating to the treatment and technique, and daily changes in setup position.
setup margin (SM)
is an organ that may remain in the treatment field, and can cause changes to treatment plans and doses (spinal cord, heart, lungs, kidney, eye, etc.).
OAR
The _____ is the combined volume of the CTV and IM.
internal target volume (ITV)
The ____ defines the volume of the OAR that may reside in the PTV during treatment.
planning organ at risk volume (PRV)
The _____ is a point outside the rapid dose change region that determines the PTV; it is easy to define and is dose-definable physically.
ICRU reference point and dose
Focalized blocks are made up of
lead or Cerrobend
Cerrobend is a mixture
of _____ that melts at ____ and has
an HVL of ____
lead (26.7%), bismuth (50%), zinc (13.3%), and cadmium (10%)
70 °C
1.3 cm
are selected for deeply seated tumors
High energies
are selected for superficially located
tumors
lower energies or electron beams
Advantages of Cerrobend
low melting point
high density
ease of shaping
low cost
Factors of energy selection
Organs at risk
Target volume
Depth
