Quiz 1 Flashcards
Abnormal growth of tissue resulting from uncontrolled progressive multiplication of cells that serves no function
Tumor
Spread of cancer beyond the primary site; tumor moves
Metastases
Depth at which electronic equilibrium occurs for photon beams; depth of maximum absorbed dose and ionizations for photons from a single treatment field, falls off after
As energy goes up, this goes further down; higher energy = lower
D-max
Region between the skin surface and the depth of D-max
In this region, dose increases with depth until it reaches a maximum at the depth of D-max
The higher the x-ray energy, the greater this
Build-up region
Dose delivered at the depth of D-max through a single treatment field; where we can calculate what is given at D-max
Given dose (GD) Applied dose D-max dose
Unit of time; unit of output measure for linacs
Accelerators are calibrated so that 1 delivers 1 cGy for a standard, reference field size at a standard reference depth at a standard source-to-calibration point
Monitor unit (MU)
1 MU = ? cGy
1 cGy
Average daily dose
180-280 cGy
Point of intersection of the three axes of rotation of the treatment unit; gantry, couch and collimator rotate around this point in space, usually tumor
Isocenter
Central portion of beam emanating from the target, only part of the beam that doesn’t diverge
Central axis (CA)
Distance from the source to the patient’s skin; disadvantage: have to move patient to make up for difference in thickness of patient
Source-skin distance (SSD) set-up
Distance from source to the axis of rotation of the treatment unit (isocenter)
Source-axis distance (SAD) set-up
Unblocked or open field size projected at the reference distance, usually the isocenter (100 cm)
Collimator field size
Equivalent rectangular field dimension of the open treatment area within the collimated field
Ex: MLCs, aperture block
Blocked (effective) field size
Small packet of electromagnetic energy (ex: x-rays, gamma rays, etc.)
Photon energy
Negatively charged subatomic energy that can be accelerated by a variety of machines or emitted from decaying isotopes
Electron energy
Tool that modifies the isodose distribution of a beam to correct for tissue inhomogeneities by progressively decreasing beam intensity across the field irradiated
Wedge
Correct for tissue inhomogeneities
Compensating filter
Used to form/shape treatment field made of 50% bismuth, 26.7% lead, 13.3% tin and 10% cadmium; low melting point but toxic
Cerrobend block
Distinct part of a linac that allows treatment field shaping and blocking through the use of motorized leaves and the head of the machine
Multi-leaf collimators (MLCs)
Extended metal structure used to restrict the useful beam to the required size
Electron application (cone)
Extension cone
Cylinder
Tissue equivalent material placed on the skin to increase skin dose and even out irregular contours on the patient (similar Z to tissue)
Bolus
Allows part of the beam to pass through while reflecting the other part of the beam; prevents beam from diverging into other part of field
Beamsplit
Immobilization devices created from styrofoam shell and foaming agents
Alpha cradle
Immobilization device that consists of a cushion and a vacuum compression pump (“beanbag”)
Vac-Lok
Thermoplastic immobilization device; facemask
Aquaplast
Used to help immobilize and position tongue
Bite block
Lasers that project a small red or green beam of light toward the patient to set up the patient for right treatment
5: right, left, ceiling, floor, back
Positioning lasers
Treat patient with one field
Single field
Pair of fields directed along the same axis from opposite sides (ex: AP and PA)
Parallel opposed fields
Two oblique fields which are similar to a breast bridge, skim the field
Tangential field
Distance from midline to side
Breast bridge
Isocentric technique where the beam moves continuously about the patient
Rotation/arc therapy
Treatment at a short distance; uses radioactive material to deliver dose administered directly into the tumor
Used in early stage disease or as a boost (ex: prostate seeds)
Brachytherapy
Shows distribution of absorbed dose and points of equal dose
Isodoses
Organs that limit the dose or dose that can be tolerated by critical structures
Critical organ dose
Normal tissue or vital organs whose radiation tolerance limits the deliverable dose
Critical structures
Normal tissues (critical structures) in which sensitivity to radiation damage may influence treatment planning and/or delivery of a prescribed dose of radiation
Organ at rise (OAR)
Distance between the borders of two adjacent fields, usually measured on the patient’s skin; used to measure and verify the depth at which two adjacent fields abut
Gap
The use of imaging to compare the position of external set-up marks and internal anatomy to the treatment plan; ex: CT, portal imager (mV and/or kV), etc.
Image guided radiation therapy (IGRT)
Therapy that delivers non-uniform exposure across the beam’s eye view (BEV) using a variety of techniques and equipment
Changes dose distribution between each field; static field
Inversed planned type treatment
Intensity modulated radiation therapy (IMRT)
Visualization perspective that is “end-on” or positioned as if looking at a volume from the source or radiation; made possible from collected CT data, this perspective is essential in three-dimensional planning
Beam’s eye views (BEVs)
Type of specialized IMRT where it delivers radiation by rotating the radiation machine through one or more arcs while radiation is continuously delivered
Volumetric modulated arc therapy (VMAT)
Type of radiation therapy in which the radiation is delivered slice by slice; 6x energy
Treatment unit where the linac rotates continuously while the treatment couch moves through the gantry bore producing a spiral treatment beam
Tomotherapy
Radiation therapy unit that accelerates electrons and produces x-rays or electron treatments
Linear accelerator (linac)
About 1 in ____ women will develop cancer (____ out of 100)
3; 33
About 1 in ____ men will develop cancer (____ out of 100)
2; 41
Cancer contributes to 1 out of every ____ deaths
4
Cancer is ________ to heart disease as the most common cause of death
2nd
______ deaths a day from cancer in the US
1650
Preventative treatment (ex: treat brain for small cell lung cancer)
Profolactic
Uncontrollable growth of irregular cells; will grow as long as it can
Poor cell differentiation
Invades other tissues (altered surface enzymes allow tumor to grow into other tissues)
Grow at new sites (lymph, blood, etc.)
Avoid immune system (immunotherapy)
Autonomy
Cancer cell
Increased growth
-plasia
Abnormal
Dys-
Disorganized growth
Dysplasia
Increased, excessive
Hyper-
Quality or state of being self-governing; self-directing freedom, especially moral independence
No limitations of growth
Autonomy
Tumors that often invade and destroy normal surrounding tissue and, if left untreated, can cause the death of the host
Have no purpose and immortal
Malignant
Increased cellularity (number of cells increase)
Hyperplasia
After
Meta-
Abnormal appearing of cells, start seeing different cells in an area; not counted as malignant (ex: Barrett’s esophagus)
Metaplasia
More
Pleo-
Variance in size and shape of cells
Pleomorphism
Cell looks the same as the cell it originated from
Well differentiation
Cell looks unlike cell it originated from; more sensitive to radiation
Poor differentiation/anaplastic
2 types of exposure to carcinogens
Incomplete
Complete
Requires same cell to be affected by promoter, can’t cause cancer on its own (ex: UV light, hormones, etc.)
Incomplete exposure
Directly causes cancer (ex: chemicals, viruses, environment)
Complete exposure
3 stage theory of carcinogens
Initiation
Promotion
Progression
4 stages of cell growth
Initiation
Promotion
Progression
Metastasis
Altered DNA cell leads to mutation
Initiation
Promoting agent enhances faulty DNA (preneoplastic to neoplastic)
Promotion
New growth of tumor cell (neoplasm)
Progression
Cell growth, spreads from one point to another
Metastasis
Study of the causes of disease
Etiology
Controls cellular division of normal calls; can become oncogen
Protooncogenes
Gene that regulates the development and growth of cancerous tissues; on/off switch of cancer cells
Oncogene
Gene whose presence and proper function produces normal cellular growth and division; absence or inactivation of such a gene lease to uncontrolled growth
Arrest the damaged DNA to give it time to repair itself
Tumor-suppressor gene
New growth
Neoplasia
Provides information about its biological aggressiveness and is based on the degree of cell differentiation
Grade
Cancers grow by reproducing cells; completes cell cycle by loses restriction at ________
G0 (resting phase)
Time it takes for tumor to double in size (can be hours to months)
Doubling time
Earliest cancer can be detected on x-ray
30 doublings will reach 1 cm in size (about size of a marble)
_____ more doublings past 30 can lead to death
10
Change in ________ can help detect cancer early
WBC count
Greatest risk of developing cancer
Age
Multiple types of cells in tumor volume with a different response to radiation
Tumors are not just one type of cell
Tumor heterogeneity
5 ways cancers metastasize
Enter blood and lymph vessels (most common)
Invasion of adjacent tissues, continuously growing
Invasion/evasion of immune system
Reentrance into distant tissue
Implantation of malignant cells in new tissue
Implantation of malignant cells in new tissue
The spillage of tumor cell clusters and their subsequent growth as malignant implants at a site adjacent to an original tumor
Can happen during surgery (tumor removed and part left or falls off somewhere else and grows)
Seeding
Cancer cells break away from tumor and disseminate in blood
Intravasation
Certain cancer cells go to certain sites (ex: prostate to bone)
Homing
Process by which vascular networks (blood supply) are created to sustain malignant tumors
Angiogenesis/neovascularization
Metastasis = stage ?
4 (highest, poor prognosis)
4 common metastatic sites (most to least common) of lung cancer
Liver
Adrenal glands
Bone
Brain
4 common metastatic sites (most to least common) of breast cancer
Lymph
Bone
Lung
Liver
Common metastatic site of stomach cancer
Liver
2 common metastatic sites (most to least common) of anus cancer
Liver
Lungs
3 common metastatic sites (most to least common) of bladder cancer
Lungs
Bone
Liver
3 common metastatic sites (most to least common) of prostate cancer
Bone
Liver
Lungs
3 common metastatic sites (most to least common) of uterine cervix cancer
Lungs
Bone
Liver
Common metastatic site of colon cancer
Liver (direct hepatic drainage)
Common metastatic site of sarcomas
Lungs
3 patterns of cancer occurrence
Sporadic
Inherited
Familial cancer
Most cancers arise spontaneously (most common pattern of occurrence; no history or exposure to carcinogens
Occurs later in life (greater than 50 years)
Sporadic
Family has pattern of cancer, patient inherited faulty repair gene
Rare (less than 10% of all cancer)
Typically occur at younger age/earlier in life
Requires promoter, bilateral
Ex: breast cancer about 5%
Inherited
Certain cancers happen enough that it can’t be related to chance but is not genetic
Families share certain risk factors (ex: smoke, diet) and environment
Occurs later in life
Familial cancer
Between ____% to _____% of all cancers are associated with lifestyle (ex: smoking and diet)
60% to 70%
Most preventable cause of cancer
Cigarette smoking
3 patterns of cancer occurance
Sporadic
Inherited
Familial cancer
Most cancers arise spontaneously, no history or exposure to carcinogens; occurs later in life (greater than 50 years)
Sporadic
Family has pattern of cancer, patient inherited faulty repair gene; two or more generations diagnosed with the same or related forms of cancer
Rare, less than 10% of all cancers
Typically occurs at younger age/earlier in life
Requires promotor
Usually bilateral, multifocal, or multiple primary tumors in one or more family members
Ex: about 5% of breast cancer
Inherited
Certain cancers happen enough that it can’t be related to chance but it’s not genetic
Families share certain risk factors (ex: smoke, diet) and environment
Occurs later in life
Familial cancer
Between ____% to ____% of all cancers are associated with lifestyle (ex: smoking, diet)
60% to 70%