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334 Cards in this Set

  • Front
  • Back

Procedure Most Likely to Employ Negative Shielding

Nasopharynx Treatment
Oblique Field Used to Treat Patients Who Have Had a Right Pneumonectomy
Factor Dmax is Most Dependant On
Physical Tissue Density
Complication That May Occur at Doses of 2000 cGy or More to the Stomach or Small Intestine
Intestinal Hemorrhage
Treatment Depth for 13 MeV Beam
3-4 cm
Time Patient is Most at Risk of Experiencing Radiation Nephropathy
A Few Weeks After Treatment Finishes
Type of Treatment For Which Dose Must Be Verified By an Ion Chamber
Most Commonly Diagnosed Head and Neck Cancer
Oral Cavity
Types of Cervical Cancer Considered Stage I
Carcinoma in Situ
Factor Which Increases the Likelihood of a Photoelectric Interaction Occuring
Higher Atomic Number
Upper Limit for KeV to Result in Photoelectric Interactions
60 KeV
Tolerance for Split Field Test for Parallel Opposed Fields
Greater Than 2.2 mm Gap
Tolerance Dose for Cataract Development
500 cGy
Condition Which Occurs as the Result of Renal Disease
Tolerance Dose for Blindness as the Result of Irradiation of the Optic Nerve or Chiasm
5500 cGy
Complication Most Likely to Result From Exposure to 1.4 Sv (140 rem) Over a Year
Examples of Deterministic Effects of Radiation
Cataract, Infertility, Erythema
Examples of Stochastic Effects of Radiation
Secondary Malignancy, Genetic Aberrations
Type of Effect for Which There Is a Threshold Dose
Deterministic Effects
Type of Effect for Which There Is No Safe Threshold Dose
Stochastic Effects
Factor Dependant on Dose for Deterministic Effects
Severity of Reaction
Factor Dependant on Dose for Stochastic Effects
Probability of Reaction Occuring
Tolerance Dose for Parotid
3200 cGy to 2/3 of the Parotid
Tolerance Dose for Heart
1/3 - 6000 cGy
2/3 - 4500 cGy
3/3 - 4000 cGy
Tolerance Dose for Brainstem
1/3 - 6000 cGy
2/3 - 5300 cGy
3/3 - 5000 cGy
Tolerance Dose for Esophagus
1/3 - 6000 cGy
2/3 - 5800 cGy
3/3 - 5500 cGy
Tolerance Dose for Rectum
6000 cGy
Tolerance Dose for Lung
1/3 - 4500 cGy
2/3 - 3000 cGy
3/3 - 1750 cGy
Tolerance Dose for Kidney
1/3 - 5000 cGy
2/3 - 3000 cGy
3/3 - 2300 cGy
Tolerance Dose for Liver
1/3 - 5000 cGy
2/3 - 3500 cGy
3/3 - 3000 cGy
Tolerance Dose for Spinal Cord
5-10 cm - 5000 cGy
20 cm - 4700 cGy
Types of White Blood Cells
Monocytes, Neutrophils, Eosinophils
Side Effect That Can Result in a Treatment Break For Patients Undergoing Pelvic Treatment
Acute Enteritis
Most Commonly Diagnosed Malignancy in Pregnant Women
Normal Red Blood Cell Values in Adult Males
5,000,000 / cc
Amount of Radiation a Patient Is Required to Have a Private Room and Bath If They Exceed
30 mCi Administered
5 mRem / hr 1 m From Their Skin Surface
Tool Used to Measure Jaw Symmetry
Machinist's Dial Indicator
Dose Equivalent Limit for Infrequent Exposures to the Public
5 mSv
Effect Of Increased Field Size On Exposure Rate
Increased Exposure Rate
Type of Treatment Machine Requiring 2 Independent Dose Monitors
Linear Accelerator
Phases of Grieving
Functions of a Hickman Catheter
Chemotherapy Administration
Blood Draws
Parenteral Nutrition
Cause of Petechiae
Chemotherapy Leading to Blood Clotting Disorders
Dose Equivalent Limit for Entire Gestation of Health Care Worker
0.5 mSv
Clonal Expansion
Many Cells Produced From a Single Cell
Mechanism That Transforms Cell Populations Into Neoplasms
Effect of Shock on Blood Pressure
Patient is Hypotensive
Exposure Limit for Controlled Areas
1 mSv / week
Mechanism That Bends the Electron Stream Onto the Target
Beam Transport System
Five Rs of Radiobiology
Therapeutic Ratio Equation
Frequency of Testing X-Ray Output Consistency
Stage I Hodgkin's Disease
Disease Within a Single Lymph Node Region or a Single Extralymphatic Site without Lymph Node Involvement
Stage II Hodgkin's Disease
Disease Within More Than 1 Lymph Node Region on the Same Side of the Diaphragm or Disease Within an Extralymphatic Site With Lymphatic Involvement, With Entire Scope of Disease Limited to One Side of the Diaphragm
Stage III Hodgkin's Disease
Disease Exists On Both Sides of the Diaphragm
May Include Extralymphatic Extension or Involvement of the Spleen
Stage IV Hodgkin's Disease
Diffuse Involvement of 1 or More Extralymphatic Organs or Extralymphatic Disease and Distant Metastatic Spread
Diseases Treated With Whole Abdomen Fields
Ovarian Cancer
Bulky Seminomas
Wilm's Tumors
Abdominal Disease Not Treated Using Whole Abdomen Fields
Most Common Form of Esophageal Cancer and Percentage of Diagnoses This Accounts For
Squamous Cell Carcinoma
Type of Esophageal Cancer Associated with Barrett's Esophagus
Complication That May Occur as the Result of Exposures of 1500 cGy or More to the Prepubescent Breast
Stunted Breast Development
Presence of Poisonous Blood Products in the Patient's Blood As the Result Of Kidney Failure
Location of the Pancreatic Head
In the C Loop of the Duodenum
Most Serious Consequence of Whole Body Irradiation
Hematopoietic Suppression
End Points for Tolerance of the Rectum
End Point for Tolerance of the Heart
End Points for Tolerance of the Esophagus
Clinical Stricture
End Point for Tolerance of the Lung
End Points for Tolerance of the Spinal Cord
End Points for Tolerance of the Brainstem
End Point for Tolerance of the Liver
Liver Failure
End Point for Tolerance of the Kidney
Clinical Nephritis
Type of Cancer Examined Using Lymphangiogram
Testicular Cancers
Most Common Region of Bulge Within the Electron Isodose Lines
20 - 40 %
Depth of 50% Depth Dose at Central Axis for a 10 x 10 Field on a CO-60 Machine
12 cm
Rationale for Treating Obese Female Patients Undergoing Pelvic Irradiation in the Prone Position
Decreased Dose to the Patient's Bladder
Most Common Cause of Light Field Incongruence In a High Energy Linear Accelerator
Misaligned Collimator Mirror
Ideal Parameters for Phantoms
Same Electron Density
Same Atomic Number
Same Mass Density
Method of Maintaining Skin Sparing On a Sloped Skin Surface
Compensating Wedges
Equation for Determining Dose for High Energy Electron Beams
MU = Prescribed Dose / (cGy / MU)(Area Factor)(% Depth Dose)
Factors That Must Be Included When Labeling Wedges
Wedge Angle
Name of Treatment Unit
Maximum Field Size
Symptom Treated Using Decongestants for Patients Undergoing Nasopharyngeal Treatment
Serous Otitis Media
Hinge Angle Equation
Wedge Angle = (180 - Hinge Angle) / 2
Hinge Angle
Angle Separating the Two Central Axes
Rationale for Using Wedges to Treat Laryngeal Cancers
Used to Modify Isodose Distribution, and Not to Decrease the Number of Hot Spots
Legal Violation for Intentionally Failing to Cover a Patient
Invasion of Privacy
Block Used for the Longest Source to Surface Distance
Straight Block
Best Way to Avoid Being Charged With Assault
Explanation of All Actions to the Patient
First Sign of Bacterial Infection
Temporary Increase in the Number of Leukocytes
Graduated Sound for Measuring the Depth of the Uterine Cavity
Medical Instrument Designed to Facilitate Vaginal Treatment
Method Used to Treat Tumors On Large, Curved Surfaces, Such As Superficial Chest Wall Disease
Electron Arc
Type of Cancer Most Likely to Result in Superior Vena Cava Syndrome
Metastatic Disease to the Brain or Spinal Cord
Appearance of Mucosa Immediately Following the Completion of Treatment for Laryngeal Cancer
Irregular Mucosal Slough
Side Effect That Occurs As the Result of Intracellular Edema
Moist Desquammation
Condition Minimized Using the Application of Cornstarch
Radiation Induced Skin Reaction
Decrease in the Number of Circulating Red Blood Cells
Highest Dose to Which Structure Using High Energy Photons to Treat With a Bone Interface
Soft Tissue Surrounded By Bone
Virtual Source
Point From Which An Electron Beam Appears to Diverge
Primary Lymphatic Drainage of the Paranasal Sinuses and Nasal Pharynx
Retropharyngeal Lymph Nodes
Advantage of Cerrobend in Block Construction Versus Lead
Lower Temperature Required to Shape
Factors Linear Attenuation Coefficient Is Dependant On
Beam Energy
Physical Density of Attenuating Material
Atomic Number of Attenuating Material
Tolerance Dose of Whole Brain Treatment
6000 cGy
Impact of Treating Less Cross-Sectional Area
Decreased Exposure Rate On the Patient's Skin Surface
Limit for Radioactivity Surrounding a Patient Who Is Emitting Radiation's Room
5 mRem / hr
Malignant Cancer Arising From Epithelial Cells
Structures Shielded Treating Mantle Fields
Humeral Heads
Spinal Cord
Lymph Node Regions Included in Mantle Fields
All Major Regions Above the Diaphragm
Superior Border of Mantle Field
Inferior Border of Mandible Anteriorly
To Include Occipital Nodes Posteriorly
Inferior Border of Mantle Field
Level of the Insertion of the Diaphragm
About T10
Lateral Borders of the Mantle Field
To Include the Axillary Lymph Nodes
Patient Position for Treating Mantle Fields
Arms Akimbo
Chin Fully Extended
Rationale for Chin Extension Treating Mantle Fields
Spares Oral Mucosa, Particularly Posterior Field Exit Dose
Tolerance Dose of Pituitary
4500 - 5500 cGy
Dose Equivalent Limit for Annual Occupational Exposure
50 mSv (5 rem) for Stochastic Effects
Annual Dose Equivalent Limit for Lens of the Eye
150 mSv (15 rem)
Dose Equivalent Limit for Annual Occupational Exposure for Deterministic Effects on Whole Body
500 mSv (50 rem)
Dose Equivalent Limit for Cumulative Radiation Exposure
10 mSv (1 rem) x Age In Years
Annual Dose Equivalent Limit for Continuous or Frequent Public Exposure
1 mSv (0.1 rem)
Dose Equivalent Limit for Exposure to an Embryo or Fetus
0.5 mSv (0.05 rem) / month
5 mSv (0.5 rem) Over Course of Gestation
Annual Negligible Individual Risk Level Dose Equivalent
0.01 mSv (0.001 rem)
Cancer Arising From Mesenchymal Tissue, Including Connective, Supportive, or Soft Tissue
Growing Outward From Anatomical Structures
Primary Lymphatic Drainage of the Colon
Internal and Presacral Mesenteric Lymph Nodes
Structures Destroyed As a Consequence of Large Lymphoid Irradiation
Treatment Used for Generalized Abdominal Disease
Whole Abdomen Irradiation with Boost
Beam Energy Above Which Backscatter at Depth Dose Becomes Negligible
8 MV
Diagnostic Test Used for Bladder Carcinomas
Factors Which Impact the Effect of Homogeneities
Size of Inhomogeneity
Type of Radiation Delivered
Energy of Radiation Delivered
Maximum Energy of a Scattering Object at a 180 degree Angle
511 KeV
Treatment Options for Early Stage I Wilm's Tumors
Postoperative Radiation Therapy
Substances Used to Deliver Immunotherapy
Monoclonal Antibodies
Common Characteristics of Neoplastic Processes
Symptoms of Radiation Induced Acute Hepatitis
Portal Vein Hypertension
Use of Scatter - Air Ratio
Determination of Amount of Scatter Produced by Irregular Fields
Factors Which Influence the Shape of Isodose Curves
Wedge Angle
Cold Spot Resulting From Treatments Using Proimos Head Treatment Device
Behind Acanthion
Primary Goal of Radiation Simulation
Assurance That Treatment Fields Enchompass the Target Value
Normal Adult Blood Pressure
120 / 80 mmHg
Hormonal Conditions Associated With Increased Bone Turnover
Increased Parathyroid Hormone
Increased Adrenal Cortical Hormone
Decreased Calcitonin
Malignant Transformation
Process By Which Normal Cells Acquire the Properties of Cancer
Substances That Synthesize Antimicrobial Proteins Which Attach to the Bacterial Surface
Treatment Most Likely to Result in Decreased Number of White Blood Cells
Skeletal Disease
Organ for Which Radiation Treatment is Most Likely to Result in Immunosuppression and Decreased Blood Counts
Percentage of Radiation Dose Absorbed in the First 2 cm of an Orthovoltage Beam
Region Esophageal Adenocarcinomas Are Most Likely to Develop
Lower Thoracic Esophagus
Region of Internal Mammary Lymph Nodes
Lateral Border of the Sternum
Consequence of Diminished Pituitary Function
Decreased Sex Hormone Production
Decreased Cortisone Production
Decreased Thyroxin Production
Early Response to Irradiation of the Lung
Radiation Pneumonitis
Most Common Cause of Mechanical Bladder Obstruction
Enlarged Prostate Gland
Factors Influencing Prescribed Dose
Cytogenetic Factors
Diagnostic Stage
Pathologic Grade
Potential Complication of Apical Lung Treatments
Extremity Defects Secondary to Brachial Plexus Injuries
Systems That Originate As the Endoderm
Gastrointestinal System
Genitourinary System
Respiratory System
Structures That Are Most Likely to Experience Chemical Changes Resulting in Radiation Induced Cell Death
Cell Membranes
Tolerance Dose for the Brachial Plexus
5500 cGy
Percentage of Patients Who Develop Liver Metastases
Mechanism of Liver Metastases
Filtration of Hematogenous Tumor Cells
Primary Lymphatic Drainage from the Testis
Para-Aortic Lymph Nodes
Organs at Risk During Intracavitary Cervical Brachytherapy
Purpose of Shielding
Avoid Unneccessary Exposure to Surrounding Tissues
Not To Protect All Critical Organs
Mechanism of Flattening Filter for Treatment Using a 4 MV Beam
Decreased Dose Away From the Central Axis
Lymphatics Usually Included In Breast Treatment
Internal Mammary
Situation Requiring the Employment of TAR
Variable SSD
Presence of Disease Within the Patient's Cervical Lymph Nodes Demands Inclusion of Which Structure Within the Treatment Volume
Most Common Mechanism of Spreading Infection Within the Hospital
Direct Contact
Clinical Management of Small Bowel Symptoms
Avoid Excessive Fiber Consumption
Avoid Lactose
Avoid a High Fat Diet
Exposure Accuracy for the Dose Delivery System
Within 5% of the Delivered Dose
Disregard for Normal Limitations of Growth Exhibited By Cancer Cells
Equivalent Dose Limit for Occupational Exposure to the Lens of the Eye for Deterministic Effects
150 mSv (15 rem)
Complication Suggested By Dry Cough and Shortness of Breath When Treating Thymomas
Radiation Pneumonitis
Abnormal Increase in Cells of a Tissue or Organ With Subsequent Enlargement or Increased Response to Stimulus
Factors Most Likely to Interfere With Accuracy of Pap Tests
Vaginal Infections
Parameters for Imaging Port Films
Single Emulsion Film
Lead Cassettes
Skin Care Recommendations
Use Mild Soap Only
Continue Using Appropriate Topical Steroid Creams
Contraindication for Continuing Hodgkin's Disease Treatment
White Blood Cell Count Under 2000
Normal White Blood Count Values
4300 - 10800
Stage I Cervical Cancer
Cervical Cancer Confined to the Uterus
Stage II Cervical Cancer
Cervical Cancer Invading Beyond the Wall of the Uterus But Not To The Pelvic Sidewalls or Lower 1/3 of the Vagina
Stage III Cervical Cancer
Tumors That Extend To the Pelvic Sidewall or Lower 1/3 of the Vagina
Tumors That Cause Hydronephrosis or a Nonfunctioning Kidney
Stage IVA Cervical Cancer
Tumors Tha tInvade the Mucosa of the Bladder or Rectum
Tumors That Extend Beyond the True Pelvis
Difference Between Tissue Air Ratio and Percent Depth Dose
Percent Depth Dose is Dependant on the SSD and Tissue Air Ratio Is Not
Structures That Are Always Included in Nasopharynx Fields
Posterior 1/3 of the Orbits
Retropharyngeal Lymph Nodes
Structure Which May or May Not Be Included in Nasopharynx Fields
Base of Skull
More Radiosensitive Muscle
Pterygoid Muscle
Factor With Greatest Influence of Delivery of Dose at Depth Treating Using MV
Beam Quality
Factors Geometric Divergence is Dependant Upon
Field Diameter
Treatment Angle
Most Common Location For Vaginal Cancers
Posterior Upper 1/3 of the Vagina
Most Common Pediatric Malignancy
Acute Lymphocytic Leukemia
Form of Acute Leukemia Diagnosed Most Often in Adults
Acute Myelogenous Leukemia
Peak Age of Incidence for Chronic Lymphocytic Leukemia
71 years
Rarely Diagnosed in Patients Under the Age of 40
Peak Age of Incidence for Chronic Myelogenous Leukemia
Mid 40s
Rarely Diagnosed in Patients Under the Age of 20
Medium Used to Calibrate Electron Beams
Distilled Water
Lymph Nodes Included in Treament Fields for Prostate Cancer Treatment
Obturator Lymph Nodes
Common Iliac Lymph Nodes
Purpose of Cerebral Spinal Fluid in Ventricles of the Brain
Mechanical and Immunological Protection of the Brain
Yellowing of the Skin Without Yellowing of the Eyes
Organ at Greatest Risk for Complication Using 4500 cGy to Treat the Whole Abdomen
Conversion Factor For Sv and Gy
1 Sv = 1 Gy
Conversion Factor for Rad and Gy
1 Gy = 100 rad
Conversion Factor for Curies and Bq
1 Ci = 3.7 x 10E10
Conversion Factor for Rem and Sv
1 Sv = 100 rem
Conversion Factor for Gy and J/kg
1 Gy = 1 J/kg
Used to Evaluate the Distribution, Uniformity, and Symmetry of Brachytherapy Sources
Type of Cancer Diagnosed Most Often in the Vagina
Squamous Cell Carcinoma
Characteristics of Nodular Sclerosing Hodgkin's Disease
Many Reed Sternberg Cells
Lacunar Spaces
Liver Secretions Active in Blood Coagulation
Most Common Complication Associated with Eustachian Tube Inflammation Following Radiation Treatment
Serous Otitis Media
Target Volume
Area of Known and Presumed Tumor
Treatment Volume
Target Volume and Margin for Limitations of Setup Technique
Most Common Sites of Skin Cancers
Most Common Sites of Melanomas
Women's Legs
Men's Trunks and Faces
Relative Biologic Effectiveness Equation
Dose From 250 keV x-ray / Dose From Test Radiation Needed to Produce the Same Biologic Effect
Converts Kinetic Energy to Microwave Energy in Linear Accelerators Using Microwave Cavities Tuned Near Operating Frequency of the X-ray Tube
Linear Energy Transfer
Average Energy Deposited Per Unit Length To a Medium By Ionizing Radiation As It Passes Through the Medium
Relationship Between LET and RBE
Directly Proportional
Protraction Rate
Total Extent of Time Over Which The Dose Is To Be Delivered
Oxygen Enhancement Ratio
Comparison of Response of Cells to Radiation in the Presence and Absence of Oxygen
Oxygen Enhancement Ratio Equation
Radiation Dose Under Hypoxic or Anoxic Conditions / Radiation Dose Under Oxic Conditions to Produce the Same Effect
Relationship Between Oxygen Enhancement Ratio and Relative Biologic Effectiveness
Not As Straightforward, But Directly Proportional Under Ideally Oxygenated Conditions
Dose Resulting in Hematopoietic Syndrome
100 - 1000 cGy
Dose Resulting in Gastrointestinal Syndrome
1000 - 10000 cGy
Dose Resulting in Cerebrovascular Syndrome
5000 - 10000 cGy
Survival for Persons With Hematopoietic Syndrome
3 weeks - 2 months
Survival for Persons With Gastrointestinal Syndrome
3 - 10 days
Survival for Persons With Cerebrovascular Syndrome
Less Than 3 days
Stages of Radiation Syndromes
Prodromal Stage
Latent Stage
Manifest Illness
Symptoms of Prodromal Stage of Hematopoietic Syndrome
Symptoms of Prodromal Stage of Gastrointestinal Syndrome
Symptoms of Prodromal Stage of Cerebrovascular Syndrome
Loss of Consciousness
Burning Sensation of the Skin
Duration of Stages of Hematopoietic Syndrome
Prodromal Stage - Hours After Exposure
Latent Stage - Few Days to 3 Weeks
Manifest Illness - 3 - 5 Weeks After Exposure
Death - Within 2 - 6 Weeks, If Fatal, Dose Dependant
Symptoms of Manifest Illness of Hematopoietic Syndrome
Serious Infection
Duration of Stages of Gastrointestinal Syndrome
Prodromal Stage - Within Hours of Exposure
Latent Stage - 2 - 5 Days After Exposure
Manifest Illness - 5 - 10 Days After Exposure
Death - During Second Week After Exposure
Symptoms of Manifest Illness for Gastrointestinal Syndrome
Biologic Mechanism Responsible for Gastrointestinal Syndrome
Depopulation of Crypt Cells, and Subsequent Denudation of the Villi
Decreased Absorption
Leakage of Fluid Into the Lumen
Bacteria Can Access Circulating Blood, Leading to Overwhelming Infection
Bone Marrow Demonstrates Severely Decreased Amount of Circulating Leukocytes
Electrolyte Imbalance
Amount of Time to Recover From Hematopoietic Syndrome
3 weeks - 6 months, Dependant on Dose
Duration of Stages for Cerebrovascular Syndrome
Prodromal Stage - Minutes - Several Hours Following Exposure
Latent Stage - Several Hours or Less if Detectable
Manifest Illness Stage - 5 - 6 Hours After Exposure
Death - Less Than 3 Days
Symptoms of Manifest Illness for Cerebrovascular Syndome
Watery Diarrhea
Possible Biologic Mechanisms for Cerebrovascular Syndrome
Extensive Blood Vessel Damage, Leading to Vasculitis, Meningitis, Edema, and Intracranial Pressure
Indirect Hit Effect
Radiolysis of Water Ultimately Responsible for Transferring Energy from Ionizing Radiation From Irradiated Molecules to Non-Irradiated Molecules
Direct Hit Effect
Radiation Damage to the DNA of the Irradiated Cells
Key Molecule Transfer
Transfer of a Free Radical to a Key Molecule That May Result in Bond Breakage or Inactivation of Key Functions
Vacuum Tube That Generates Microwaves
Hollow Tubelike Structure Directing the Microwave Power
Most Significant Component of Beam Transport System
Bending Magnet
Indications For Completing Treatment If the Door Lock is Inoperable
If Patient Setup Has Been Completed
Device Used to Measure Dose Rate Consistency
Ion Chamber
Annual Equivalent Dose for Occupational Exposure of Persons Under 18 years of Age
5 mSv (500 mRem)
Acceptance Criteria for Field Flatness Over the Central 80% of the Field Using Photons
Acceptance Criteria for Radiation / Light Field Coincidence
2 mm or 1% On Side
Interphase Death
Irradiation of the inCell During the G1, S, or G2 Phase That Results In Cell Death, Prior to Their Undergoing Mitosis
Mitotic Delay
Cells In Interphase When They Are Irradiated Which Are Delayed In the G2 Phase
Consequence of Mitotic Delay
Decreased M1 Phase Population, Resulting in Fewer Daughter Cells Produced
Effect Of Radiation Dose On Mitotic Delay
Higher Dose Results In Longer Mitotic Delay
Cellular Mechanism Involved In Mitotic Delay
Cells Attempts To Repair Injury Prior to Mitosis By Confirming DNA and Proteins Are Intact, To Avoid Disruptions in Cell Division or Cell Death
Reproductive Failure
Decrease in Reproductive Integrity or Limits To Number of Potential Divisions Following Irradiation
Type of Radiation Most Often Measured With Free-Air Ionization Chambers
X-Rays and Gamma Rays Up To 3 MeV
Consequences of Misaligned Photon Beam
Displaced Focal Spot
Asymmetric Collimator Jaws
Improper Rotational Axis of Collimator
Energy At Which Coherent or Thomson Scatter Occurs
Below the Threshold For Ionization
Energy At Which Photoelectric Effect Occurs
Photon Energies At Or Below 1 MeV
Energy At Which Incoherent or Compton Scatter Occurs
Most Radiation Treatment Energies
Energy At Which Pair Production Occurs
Above 1.022 MeV
Energy At Which Photodisintegration Occurs
Photon or Electron Beam Energies At or Greater Than 10 MeV
Thomson or Coherent Scatter
Photon Is Absorbed and Photon of Same Energy Is Emitted In a Different Direction
Photoelectric Effect
Incident Photon Penetrates Deep Into the Atom and Ejects an Inner Shell Electron From Orbit
Compton or Incoherent Scatter
Photon Ejects Outer Shell Orbital Electron and Alters Its Own Path, Generally Resulting In the Freed Electron Attaching Itself To Another Atom Shortly Thereafter
Pair Production
Photon Approaches Nucleus, Is Absorbed and Then Emitted As An Electron-Positron Pair Which Is Ejected By the Atom
Phenomenon Associated With Positron Created During Pair Production
Slows Down and Creates Annihilation Reaction, Destroying Both Positron and Electron and Leaving Two Photons Emitted Opposite Each Other Out of Their Energy
Photon Is Absorbed After Striking the Nucleus Directly, Which Then Emits Neutrons and Gamma Rays to Maintain Stability
Atomic Number of Substances Involved In Photodisintegration
High Z Materials
Generally Not Tissue, But Beam Production Devices Within High Energy Linear Accelerators, Responsible For Neutron Production In These Cases
Form of Neutron Shielding
Borated Plastic To Slow Down Neutrons and Allow For Their Capture
Skin Exposure At Double the SSD
1/4 That Of the Original SSD
Half Life Equation
Half Life = .693 / decay constant
Decay Constant Equation
- Decay Constant = Change in Number of Atoms / Change in Time
Radioactivity Equation
Activity = Initial Activity x e^(- decay constant)(time)
Mean Life Equation
Mean Life = Half Life x 1.44
Effect of Protraction Rate On Relative Biologic Effectiveness
Faster Protraction Rate Results in Greater RBE
Effect of Quality Factor On Relative Biologic Effectiveness
Higher Quality Factor Results in Greater RBE
Acceptance Criteria For Amount Of the Beam Transmitted Through the Beam Interceptor
Less Than 0.5% 1 m From The Housing
Relationship Between Therapeutic Ratio and Relative Biologic Effectiveness
Higher Values for Therapeutic Ratios Result In Greater Relative Biologic Effectiveness
Structures With Radiation Tolerance Greater Than 7000 cGy
Articular Cartilage
Tolerance Dose of Ovary and Endpoint
200-300 cGy
Condition Associated With Renal Insufficiency in Patients Who Undergo Pediatric Irradiation
Dmax for 1.25 MV Beam
1/2 cm
Dmax for 4 MV Beam
1 cm
Dmax for 6 MV Beam
1 1/2 cm
Dmax for 10 MV Beam
2 1/2 cm
Dmax for 18 MV Beam
3 1/2 cm
Dmax for 24 MV Beam
4 cm
Percent Depth Dose Equation
PDD = Absorbed Dose at Depth / Absorbed Dose at Dmax x 100%
Mayneord's Factor Equation
F Factor = [(SSD2 + Dmax)/(SSD2 + Depth)]^2 / [(SSD1 + Dmax)/(SSD1 + Depth)]^2

New PDD = Old PDD x Mayneord F Factor
When to Use Mayneord F Factor
To Determine PDD When Treating Using Different Distances
When to Use Inverse Square Law
To Determine Exposure When Treating Using Different Distances
Equivalent Square Formula
Area / Perimeter = Area / Perimeter

Equivalent Square = 4 (A/P)
Means of Localizing Pancreatic Cancers
Surgical Clips
Conformal Radiation Treatment
Using 3D Planning to Deliver Radiation to the Exact Target Volume In Any Plane
Gap Calculation Formula
Gap = (1/2)(Length1)(Depth1)/(SSD1) + (1/2)(Length2)(Depth2)/(SSD2)
Device Used To Correct an Oblique or Curved Skin Surface Approximated With a Straight Line
Compensating Wedges
Fields Used For Esophagus Treatment
AP/PA and Oblique Opposed Fields
Depths Usually Treated Using Wedge Pair Fields
A Few cm Below Skin Surface
Dmax Equation
Dmax = (DD / PDD)(100)
Common Cerrobend Block Thickness Treating Using MV
7 1/2 cm
Acceptable Amount of Beam Transmission Through a Block
Limitations of Ultrasound
Waves Reflected By Air, Limiting Use With Structures That Contain or Are Surrounded By Air
Reason Compensators Should Remain 15 cm or Further From the Patient's Skin
To Preserve Skin Sparing
Purpose of Scattering Foil
More Homogeneous Dose Distribution When Treating Curved Surfaces Being Treated Using Electrons
Beam Energy Plane Parallel Ionization Chambers Are Calibrated To
20 MeV
Device Used to Measure Electron Beams for TG-21 Protocol
Plane Parallel Ionization Chamber
Application of Coefficient of Equivalent Tissue
To Correct For Tissue Inhomogeneities By Equating Them To Equivalent Thickness In Water
Most Common Side Effects From Palliative Radiation Therapy to the Brain
Cerebral Edema
May Lead to Memory Impairment
Factors That Impact Backscatter Factor
Beam Quality
Field Size and Volume Being Irradiated
Effects Of Increased Field Size
Higher Dose To the Buildup Region
Less Skin Sparing
Equivalent Depth of Calibration for MV Photons Up To 6 MV
5 cm Water
Factors Influencing TAR at Depth of Dmax
Size Of Field Less Significant
Relationship Between Isodose Depth and Beam Quality
Directly Proportional
Effect Of Beam Energy On Penumbra
Higher Energy Results in Wider Penumbra
Effect of Field Size On Penumbra
Larger Field Size Results in Wider Penumbra
Maximum Dose For Hot Spots In Wedge Pair Treatments
Interface Which Results In Most Echo Reflection During Ultrasound
Soft Tissue vs. Bone Interface
Site Most Likely to Metastasize To the Liver vs. Other Sites
Site Most Likely to Metastasize To the Liver Overall
Endocrine Function of the Kidney
Release of Renin Involved With Blood Pressure Regulation
Least Radiosensitive Structure In the Gastrointestinal System
Most Common Histology Within the Aerodigestive Tract
Squamous Cell Carcinoma
Functions of Lucite Shadow Trays
Absorption Of Electron Contamination Within the Beam
Modification Of the Build Up Curve, Being Used As a Beam Spoiler
Normal Tolerance Dose Of Radiation Nephropathy
2000 cGy
Location Of the Ovaries
Medial To the Ureter
Bone Remodeling Cycle
Involves Resorption and Formation of Bone Mass
Potential Complications Of Irradiation During Adolescence
Slipped Femoral Capital Epiphysis
Maturation Abnormalities of the Bone and Soft Tissue
Bodily Fluids Composed Predominantly Of Water and Methylcellulose
Aqueous Humor
Therapies Associated With the Complication of Pneumonitis
Radiation Therapy
Shoulder Of Survival Curve
Dose Below Which Cells Generally Are Not Accumulating Enough Damage To Be Killed
Linear Part of Survival Curve
Semilogarithmic Representation Indicating Equal Increases in Dose Result in Equal Decreases in Surviving Fraction Of Cells, With Actual Number Of Cells Varying
Extrapolation Number
Represented By n
Intersection Of Linear Part of Curve Extrapolated to the Y-Axis
Suggests Number Of Targets That Must Be Hit To Kill Cell
Range From 2 - 10 For Mammal Cells
Quasithreshold Dose
Represented By Dq
Dose At Which Survival Becomes Exponential
Width Of the Shoulder On the Survival Curve
Dose At Surviving Fraction of 1
Measure Of a Cell's Ability to Accumulate and Repair Sublethal Damage
Represented By Do or D37
Reduces Surviving Fraction Of Cells to 37%
Reciprocal Of the Slope of the Linear Part of the Curve
Measure Of Cell's Radiosensitivity
Proportional to Radioresistance
Usually Between 100 - 220 cGy For Mammal Cells
Survival Curve Equation
log(e) n = Dq / Do