RAD THERA - MIDTERM L3 Flashcards
The dose which is delivered to the point of maximum
ionization or peak dose (100%) for each beam.
Given Dose / Dmax Dose
Which photon energies express a Dmax Depth of 0.0 cm ?
- Superficial
- Orthovoltage
Cobalt-60 Dmax Depth is equivalent to ______
0.5 cm
LINAC Dmax Depth is typically equivalent to ______
1.0 cm (in reference to 4 MV Photon Energy)
Depth distribution is affected by four (4) parameters, namely:
- Beam Energy
- Field Size
- Source Distance
- Collimation
Formed by joining points of equal or similar dose along the central axis of the beam at regular intervals; representing levels of absorbed dose
Isodose Curves
The absorbed dose at some depth within the patient or phantom.
Depth Dose
These are taken using an ion chamber system and a homogenous phantom for a large number of field sizes and are plotted in terms of isodose curves
Depth Dose Measurements
A diagrammatic representation of radiation distribution in a
uniform absorber where points receiving an equal dose are joined together.
Isodose Chart
The absorbed dose at some depth within the patient
or phantom
Depth Dose
The ratio of the absorbed dose at some depth (Dd) to the absorbed dose at Dmax
Percentage Depth Dose (PDD or %DD)
The ratio of the dose at depth in a phantom to the dose in free space using the same source axis distance (SAD).
Tissue Air Ratio (TAR)
The use of TAR is limited to _______ and _____ only
Cobalt-60 and Orthovoltage Machines
The ratio of the dose at depth to the dose at Dmax, using a phantom and maintaining the same SAD for both measurements
Tissue Maximum Ratio (TMR)
Formula for TAR is
TAR = Dose at Depth Maximum / Dose at the Same Point in Free Space
Formula for TMR is
TMR = Dose at Depth / Dose at Dmax
In this technique, the axis of the beam is directly on the surface of the skin
Source-Skin Distance Technique (SSD)
SSD Technique is also called as ______
Fixed Distance Technique
In this technique, the central axis of the beam is in the
midplane of the body; used to treat risk areas occupying a large volume on a central location in the patient and maybe applied isocentrically
Source-Axis Distance Technique
SAD Technique is also known as ________
Isocentric Technique
Surface markings should be extended ______ and _____
Superiorly and Inferiorly
Every radiotherapy setup must be checked by minimum of _____ qualified RTTs
Two (2)
These are tools used to ensure and maintain the position of the patient without any movement.
Immobilization Devices
TRUE OR FALSE
Even the smallest movement of patient can result in dose variation to the surrounding tissues as well as the tumor to be treated.
TRUE
Immobilization is essential in radiotherapy to achieve (4):
- Comfort
- Stability
- Precision
- Efficiency
(Ce-Sarean-Po-Efficient)
Immobilization devices can be made _____ or by ______
- Locally
- Commercial Vendors
The following are Generic Body Supports EXCEPT:
A. Foam Wedges
B. Head Rests
C. Stirrups
D. Foam Casts
D. Foam Casts
The following are Body Casts EXCEPT:
A. Vacuum Bags
B. Thermoplastic Bags
C. Foam Casts
D. NOTA
D. NOTA
Which of the following may be considered as a Multi-use positioning device ?
A. Head Board
B. Bite Block System
C. Pig-O-Stat
D. Pedia Poser
Either A or B
This is performed to minimize the amount of gas and residue in the bowel for better images
Bowel Preparation
How many Dulcolax tablets must be taken after lunch before CT Sim appointment ?
Two (2)
What time must rectal suppository be inserted on the day of CT sim ?
5:00 AM
It has an underlying function of producing BEAM’S EYE VIEW radiographs which aid in the optimization of beam
parameters, the design of field shapes and the treatment verification process
Conventional Simulation
A machine that duplicates
radiation treatment machine in terms of its geometrical, mechanical and
optical properties, using an isocentrically mounted diagnostic and
fluorographic x-ray unit.
Conventional X-ray Simulator
TRUE OR FALSE
Field localization is a very time consuming process, which if carried out in the control room is prohibitive
FALSE
Field localization is a very time consuming process, which if carried out in the TREATMENT ROOM is prohibitive
Which of the following is NOT a treatment parameter recorded during simulation ?
A. Patient Position
B. Field Size
C. Collimator Angulation
D. Gantry Collimation
D. Gantry Collimation
(Gantry Angulation dapat para pasok)
It has emerged as a
logical, superior alternative to conventional simulation, eliminating the need for conventional simulation by generating a 3D image of a patient
CT Simulator / Simulation
CT simulation is considered as the _______ for 3D radiotherapy
Natural Precursor
Simulation is used to accurately identify ______ and ______
- Target Volumes
- Sensitive Structures
This may include any tissue presumed to contain tumor or microscopic cancer cells.
Tumor Volume
Volume treated is also determined by (4):
- History
- Pattern of Spread
- Intent of Treatment
- Tolerance of Adjacent Normal Tissues
It indicates the gross palpable or visible tumor
Gross Tumor Volume (GTV)
Indicates the gross palpable or visible tumor and a surrounding volume of tissue that may contain subclinical or microscopic disease
Clinical Target Volume (CTV)
Indicates the CTV plus
margins for geometric uncertainties, such as patient
motion, beam penumbra, and treatment setup differences.
Planning Target Volume (PTV)
Volume of the tumor and
surrounding normal tissue that is included in the isodose
surface representing the irradiation dose proposed for the treatment
Treated Volume (TV)
Volume included in an isodose surface with a possible biological impact on the normal tissue encompassed in this volume.
Irradiated Volume (IV)
The process in which a
team consisting of radiation oncologists, radiation therapist, medical physicists
and medical dosimetrists plan the appropriate external beam radiotherapy or
internal brachytherapy treatment technique for a patient with cancer
Radiation Treatment Planning
A complex process carried out prior to the administration of radiotherapy. It consists of many steps including tumor localization image acquisition, tumor volume determination, contour preparation, prescription of the dose, optimal beam placement or choice of fields and beam characteristics
Treatment Planning
This is used in external beam therapy to generate beam shapes and dose distributions with the intent to maximize tumor control and minimize normal tissue complications.
Computerized Treatment Planning System
Which CTPS part can provide a graphic display of isodose curves ?
A. TV Monitor
B. Monitor
C. TV
D. Screen Monitor
A. TV Monitor
Production of ______ is
essential for viewing the results of treatment planning and for documentation of the treatment doses
A. Soft Copy
B. Hard Copy
C. PDF
D. PNG
B. Hard Copy
Enumerate the steps involved in Radiotherapy Treatment Planning Process (6):
- CT Scanning
- Tumor Localization
- Skin Reference Marks
- Treatment Planning
- Virtual Simulation
- Radiotherapy Treatment
A single beam is used directly applied to or near the surface of the patient. The beam is centered via the use of marks or tattoos on the patient’s skin so that the tumor
on or beneath the marked skin area is contained within the beam
Single Field (Fixed Beam)
Two fields with co-incident central axis maybe applied from opposing directions,
so as to encompass a volume of tissue extending virtually from one surface of
the patient through the opposite surface
Parallel-opposed / Pair Field (Fixed Beam)
A high dose is applied for a relatively small tumor volume lies deep in the body, two or more fields with non-coincident central axis maybe directed at the tumor.
Multi-field Treatments
A patient is struck by doses in his pelvis in an AP and PA projection, which field arrangement is used:
A. Single Field
B. Parallel-opposed
C. Multi-field Treatments
D. NOTA
B. Parallel-opposed
The involvement of three projections of doses is what particular multi-field treatment type ?
Three Field Technique
This pertains to a three-field technique in different directions.
A. COD Technique
B. Crossfire Technique
C. Valorant Technique
D. Counter Strike Technique
B. Crossfire Technique
This pertains to multi field treatments with the involvement of four fields parallel to each other.
A. Box Technique
B. Square Technique
C. Quadrilateral Technique
D. Four Sides Technique
A. Box Technique
A technique that combines
intensity modulated radiation therapy (IMRT) with rotational arc delivery on the linear accelerator.
Arc Therapy (Rapid Arc Radiation Therapy)
The latest technological improvement where one single rotation of the treatment machine is used to conform the dose delivery to the target and spare organs at risk, requiring less than 2 min of beam-on time per treatment fraction.
Modulated Rotational Radiotherapy
A NEWER form of IMRT that
delivers external beam radiotherapy through a continually rotating radiation
source that encircles the patient.
Volumetric Modulated Arc Therapy (VMAT)
A method of administration of radiation by delivering it continuously over a relatively long period at a low absorbed dose rate
Dose Protraction
It is the process of dividing a
dose of radiation into multiple “fractions” lasting multiple weeks. This practice seeks to maximize the destruction of malignant cells while minimizing damage to healthy tissues
Dose Fractionation
A French physicist recognized that treatment maybe better
tolerated and more
effective if delivered more slowly with modest doses per day over several weeks
Claude Regaud
A French radiation oncologist reported impressive result
using fractionation approach in patient with locally
advanced laryngeal cancer
Henri Coutard
The four (4) R’s of Radiobiology include:
- Repair
- Reoxygenation
- Repopulation
- Redistribution
TRUE OR FALSE
Healthy cells have a greater ability to repair DNA damage than malignant cells.
TRUE
Fractionating radiotherapy allows cells which are closer to sources of oxygen to be killed first, and the intervening time between fractions allows the relatively hypoxic cells to improve their oxygen supply.
Reoxygenation
The radiosensitivity of cells depends on their _____ in the ______
- Stage
- Cell Cycle
Conventional fractionation doses range from _____ and given _____ daily
- 180 - 200 rad
- Once
Hyperfractionation doses range from _____ and given _____ daily
- 150 -300 rad
- 2-3 Times
Superfractionation doses range from _____ and given _____ daily
- 55-150 rad
- 2-4 Times
Higher doses per fraction are given fewer than five times per week
Hypofractionation
The radiation is given followed by a period of rest (1 to 2 weeks) between courses
Split Course Fraction
2000 to 3000 rad are given as a single radiation dose directly to the tumor following surgical exposure
Intraoperative Radiation
The 4Cs of Radiotherapy are comprised of:
- Control Rate
- Cure Rate
- Complication Rate
- Cost
A term used to describe the short distance treatment of cancer with radiation from
small encapsulated radionuclide sources.
Brachytherapy
Which brachytherapy dose rate is most commonly used to treat prostate cancer and brain tumors with a range of 0.4 - 2 Gy/hr
Low Dose Rate (LDR) Brachytherapy
Which brachytherapy dose rate involves placement of highly radioactive material inside the body for a short time and then retracts it with a range of greater than 12 Gy/hr
High Dose Rate (HDR) Brachytherapy
The mostly used radioisotopes for Temporary Brachytherapy are ____ and _____
- Iridium-192
- Cesium-137
A technique in which catheters and/or applicators are placed in the patient at the time of surgery and radioactive sources are loaded into the patient for treatment at a later time.
Afterloading Techniques
Medium Dose Rate (MDR) Brachytherapy ranges between _______
2 to 12 Gy/hr
The two (2) classifications of Afterloading Techniques are:
- Manual Afterloading
- Remote Afterloading
TRUE OR FALSE
If Permanent Implant Brachytherapy is used, no radioactive sources remain in the body after treatment
FALSE
If TEMPORARY IMPLANT BRACHYTHERAPY is used, no radioactive sources remain in the body after treatment
TRUE OR FALSE
HDR brachytherapy provides superior radiation dose escalation and conformality compared to EBRT.
FALSE
LDR BRACHYTHERAPY provides superior radiation dose escalation and conformality compared to EBRT.
TRUE OR FALSE
Low Dose Rate Brachytherapy is also known as Permanent Brachytherapy
TRUE
Brachytherapy may be administered via five %) treatment methods, namely:
- Intracavitary Brachytherapy
- Interstitial Brachytherapy
- Surface Application
- Intraluminal Brachytherapy
- Intraoperative Brachytherapy
Brachytherapy risks are quantitatively ______
Minimal
The other terms for brachytherapy are _____ and _____
- Curietherapy
- Endocurie
