MIDTERM PT. 3 Flashcards
WHAT ARE THE 6 KINDS OF IMMOBILIZATION DEVICES:
- ALPHA CRADLE
- THERMOPLASTIC MASK
- BREAST BOARD (BREAST STEP)
- PRO STEP
- VACUUM BAG
- HEAD REST
-incapable of movement
immobilization
___ is designed very precisely to treat exactly the right area, so it is important to keep that part of the body as still as possible
Radiotherapy
is used to make sure the patient stays in the treatment position during the course of treatment
immobilization device
are said to be the most crucial part of Radiation therapy treatment (2)
Px positioning
immobilization
for accurate delivery of prescribed radiation dose to the target volume while sparring surrounding normal and critical structures
immobilization
without proper immobilization, the patient is at risk for_____ and ______
improper treatment and unwanted side effects
Immobilazation such as __, ___, ___ and other devices are constructed to reduce set up errors and patient movement during the treatment
moulds
casts
head rest
and other devices
what is the primary goal of the immobilization system
to limit patient motion and reduce the probability of major positioning errors
a well constructed immobilization system can reduce ___ of patient setup
time
can make the Px feel secured and less apprehensive
immobilization
it can reduce the reliance on patient cooperation and alertness, it can also help to stabilize the relationship between the external skin marks and internal structures
immobilization
WHAT ARE THE DESIRABLE CHARACTERISTICS OF IMMOBILIZATION DEVICES:
- SHOULD BE TRANSPARENT TO ALLOW VISIBILITY OF BEAM LIGHT AND OPTICAL DISTANCE INDICATOR
-SHOULD BE LIGHTWEIGHT, STRONG AND DURABLE
-EASE TO USE - EASE OF MAKING THE DEVICE
-COMFORT TO PATIENT
-MINIMAL PLACE REQUIREMENT FOR THE STORAGE
-RESISTANCE TO BENDING AND STRETCHING
-MINIMAL PERTURBATION OF THE BEAM SO IT WILL NOT PRODUCE ANY ARTIFACTS IN THE IMAGE ACQUISITION
-DEVICE BE USABLE IN SIMULATOR (CT/MRI)
-SURFACE DOSE SHOULD NOT BE ALTERED
-RIGID AND HOLD IT’S SHAPE OVER TIME
-the most common immobilization device used to treat cancers
-available in different sizes and shapes
-it is rigid at room temperature
Thermoplastic mould
What ID:
when its heated in water for temperature 60-65 degrees- the material softens and become malleable
Thermoplastic mould
What ID:
when it is wet, it is placed over the patient’s body and conforms to the contour of the treatment area
Thermoplastic mould
(advantages)
-provide great reproducibility in daily treatment
-lightweight and easy to use
-modification can be made to mask if the px experienced swelling or weight loss during the course of the treatment
thermoplastic mould
(disadvantages)
-windows cut cannot be reused and when old it becomes very soft when activated
thermoplastic mould
TYPES OF IMMOBILIZATION ARE:
- HEAD & NECK IMMOBILIZATION
- IMMOBILIZATION IN BRAIN TUMORS
- THORAX AND BREAST IMMOBILIZATION
- PELVIC AND ABDOMINAL IMMOBILIZATION
- IMMOBILIZATION FOR THE BODY EXTREMITIES
preferred to used for brain & tissues
MRI
how many months does it take for thermoplastic to be used again
2-3 months
what are the parts to be immobilized in a thermoplastic:
nasal
top head
chin
sides of the ears
is one of the important parts of confirming proper treatment to the Px
initial construction and selection of proper immobilization for Head & Neck cancer
Current methods for the H&N tumors include a variety of: ___ ____ _____
masks
molds
frame systems
____ are used to pull the shoulders out of the treatment field for the neck
shoulder retractors
ID: has 5 clamps
H&N immobilization
the plate onto which the head immobilization system is secured is referred to as a ____
fixation base plate for H&N
What material do the fixation base plate for H&N is made of?
Perspex or carbon fiber
What ID: should be low z material and should attenuate the radiation minimally when the beam passes through it
fixation base plate for H&N
plate place onto the head
fixation base plate for H&N
What ID: has 3 clamps
immobilization in brain
for the general brain tumor and whole brain cases the mostly common immobilization device is the ___
3 clamp
how many clamps are used for Head and neck
5 clamps
how many clamps are used in head
3 clamps
what procedures wherein immobilization becomes more complex for radio-surgery; because the requirements for positional and numerical accuracy for the dose delivery are -+1mm: (2)
cyber knife
gamma knife
-Pxs head positioned with the chin
-hyperextended to include the superior extent of maxillary antrum in the anterior field without including the eye
Maxillary Antrum Tumor
-head positioned with the neck in extreme flexion
- anterior beam can avoid the dose-limiting structures such as the otic chiasm, the retina, and much of the brain tissue
Pituitary or small brain tumors
what are the dose-limiting structures: (3)
chiasm
retina
much of the brain tissue
WHAT ARE THE 3 COMMON IMMOBILIZATION DEVICES USED WHEN TREATING THE TUMORS IN THE CHEST CAVITY
- VACLOK
- BREST BOARD
- 2 CLAMP OR 4 CLAMP THORACIC MOULD
-consist of light weigh plastic mattress filled with radiolucent polystyrene (Styrofoam) beads
-the air is then vacuumed out of the bag for a custom fit and sealed in order to retain the shape
Vaclok
(advantages)
radio translucent, after treatment the bag is recycled and used for other
vaclok
-it is used specifically for the treatment of breast cancer
-it has several features to allow for the manipulation of patients’ arms, wrists, head, and shoulders
-allows the px to be positioned with the chest wall horizontal avoiding angulation of the collimator
breast board
breast board: are constructed by what materials which allows it to be light weight and durable
carbon fiber, thermocol
have lower attenuation levels, which permit maximum beam penetration
carbon fiber breast boards
takes advantage of gravity to pull the large. breast down into better treatment position
breast board
are used when the px is treated in a prone position- allow the small bowel to drop below the lateral field to avoid side effects
Belly board immobilization
minimizes the average volume of small bowel that would otherwise be within the lateral field during the standard box field technique treatment
belly board immobilization
immobilization system: are commonly used during the treatment of pelvic region (3)
vaclok, belly board, and thermoplastic masks
-properly maintain pxns outer contour during the treatment with respect to the isocenter
-related to the variation of internal structures during the daily treatment
pelvic immobilization
-with the thermoplastic solution it can be performed easily
-the system consists of a low-density carbon fiber base plate with leg support, two comfort cushions, and dedicated masks. the base plate can be indexed to any couch top on
-2-pin bars and multiple holes to offer maximum possibilities for positioning and immobilizing both upper and lower extremities
-for arms, elbows, etc.
Immobilization for extremities
-helps to maintain the position without strain
-the curvature of the px cervical spine can be altered by changing the support under the head
head rests and wedges
what materials are used in headrests and wedges:
Acrylic / Rubber Polyurethane
is designed for reproducible positioning and stable fixation of the base plate.
- can be placed at the desired indexing indents the couch and can be locked
indexing bar
used to maintain the pxns position during pelvis irradiation
-it avoids px tilt (rotational error
knee rest and foot rest
-helps in reproducing the opening of the mouth during the treatment
-used to minimize the volume of oral mucosa within the treatment field
-pxn mouth kept open by inserting a mouth bite mouth made from the dental impression material
-
oral prosthesis / mouth bite
an impression of the pxns teeth or gum is made in the soften dental material and within appox ___ minutes the material becomes hard
5 mins
-two-part chemical foaming agents are mixed together, initiating the chemical reaction that cause polyurethane foam to expand
alpha cradle
alpha cradle: the mixed foaming agent is distributed evenly throughout the body form and sealed inside the ____
polyvinyl bag
alpha cradle: patient is positioned in the treatment position on top of a _____ bag as the foaming agent expands ____ to ___ mins and conforms to the pxns body contour
-as the foam rises, technician maneuvers it around the px
- once the foam hardens, the customized device is ready for use
polyvinyl bag
10-15 mins
-external marks placed on either the pxns skin or the immobilization devices
- for initial laser alignment as a surrogate for internal target anatomy
-preferably made on the immobilization device as it is more reliable as opposed to the pxs skin(soft tissue & mobile)
alignment marks
alignment markers: if on skin preferably marked on ____ for a relatively fixed geometry
bony landmark
issues:
-motion of soft tissue with relation to immobilization device
-marks washing off, wearing off or migration
alignment marks
