This exam tests your knowledge of the principles of physics underlying the practice of radiation oncology. Included are questions on:

• basic physics
• instruments and measurements
• dosimetry
• radioactivity (radionuclides and physics of therapeutically employed radionuclides)
• protection and safety

Categories for Radiologic Physics for Radiation Oncology

Atomic and Nuclear Structure

• Bohr model of the atom

The classic Bohr model is the planetary model consisting of a central nucleus and planetary electrons in orbit around the nucleus.

• Coulombic force and electron binding energy

The fundamental charge on a electron is -1.602x10^-19coulombs. For protons, the charge is positive and the number of protons equals electrons in electrically balanced atoms

• Electron orbits (energy levels)

Discrete orbital energies (quanta) result in specific orbital patterns, with discrete energy transitions rather than continuous transitions. The orbital electrons are restricted to integral multiples of h/2&pi. h is Planck's Constant = 6.602 x 10^-34 Joule-second. Energy is conserved when electrons remain in a quantum orbit.

• Electron transitions—absorption and emission of energy

Electron transitions cause discrete spectral lines or energy transitions. K,L, M, N shell electron state transitions cause characteristic x-ray emission or absorption. Typical transistion energies for tungsten K series is 69.5 KeV, for L 11.0 KeV, for M 2.5 keV.

• Characteristic radiation and the Auger effect

Characteristic X-rays are emitted when an electron moves from a higher orbital energy level to another lower (ie closer) orbital. Since energy is conserved in these transitions, energy will be absorbed at a characteristic value if an electron moves to a lower energy orbit and emitted if the electron transitions to a higher energy orbit. For a K to L transition, the electon moves from a lower energy orbital to a higher energy orbital and will absorb energy equal to the difference in energy levels. For tungsten, this is 69.5 KeV - 11.0 KeV = 58.5 KeV.

If the opposite occurs, and the electon drops to a vacancy in the K shell from the M shell, a characteristic x-ray of energy 58.5 keV will be emitted.

If sufficient energy is absorbed to completely eject the electron from an inner orbit, an energy instability is created and the void will be quickly filled by an outer shell electron. This will release additional characteristic x-rays which may be emitted or absorbed by other orbital electrons, raising their energy levels. If enough energy is absorbed, a process calledAuger emissionmay occur. Energy may be transferred to other atomic electrons causing multible electrons to be ejected leaving a highly unstable atom.

• Nuclear structure
  • Nucleons —protons and neutrons

  Nuclear particles consist of quarks. The quarks are theoretical particles which make up baryons. Neutrons and protons are baryons made up of combinations of up and down quarks.

  "

  Sample Fermionic Hadrons Baryons () and Anti-baryon ()
  Symbol	Name	Quark Content	Electric Charge	Mass (GeV/c2)	Spin
  p	proton	uud	1	0.938	1/2
  p-bar	anti-proton	u-bar u-bar d-bar"	-1	0.938	1/2
  n	neutron	udd	0	0.940	1/2
  λ	lambda	uds	0	1.116	1/2
  ω	omega	sss	-1	1.672	3/2
  π+	pion	u d-bar	+1	0.140	0

   

  There is a mass difference between a proton (charge +1) and a neutron (charge 0).

  n (UDD) --> p (UUD) + β + anti-&nu_e

  There are discrete nuclear energy levels and when nuclear particles confined to a nucleus are raised to an excited state, they will attempt to return to their ground state. In the process, they will give off electromagnetic and particle radiation. ⁶⁰Co will decay by emitting a 1.48 MeV &beta particle to an intermediate energy level. This energy level is still excited but will decay further to a stable level by emission of a 1.33 MeV &gamma ray. In a second decay path ⁶⁰Co will decay by emission of a 0.32 MeV &beta and a subsequent 1.17MeV &gamma, followed by a second 1.33 Mev &gamma.

  In both cases, a neutron will lose the electron (&beta) and transform into a proton and a neutrino. A neutrino is a nearly massless and chargeless particle. Then end product will be ⁶⁰Ni which is stable.

  • Nuclear force

  There are four known natural field forces. Energy used to bind the nucleus together (protons, neutrons) include mass defect where mass is converted to energy to bind particles. These internuclear forces are:

  • Strong Nuclear force &mdash short range force acting on x < 10^-34m
  • electromagnetic force &mdash much weaker than strong nuclear force. This force acts only between particles carrying a charge and can be attractive or repulsive. It can act over long distances.
  • Weak Nuclear force — responsible for radioactive decay and neutrino interactions. The weak nuclear force is responsible for β decay. The electroweak force is a constituent force of the weak nuclear force, as it is of the electromagnetic force.
  • gravitational force &mdash very weak force operating over long (ie infinite) distances.
  • E = mc² and nuclear binding energy

  Nuclear binding energy is around 28-30 MeV

• Factors affecting nuclear stability
  • Neutron-to-proton ratio

  For stability, in light atoms the ratio of n:p is approximately 1:1. For heavier atoms, the ratio increases to approximately 1.5:1.

  • Average binding energy per nucleon

  For ⁵⁸Fe, average binding energy/nucleon is around 8 MeV

  
  
  • Pairing of similar nucleons in the nucleus

• Nuclear nomenclature
  • The four isos (isotopes, isotones, isobars, isomers)
  • Isotopes have the same atomic number -- different number of neutrons
  • Isomers have the same number of neutrons and protons but different nuclear energy levels
  • Isotones have the same number of neutrons but different mass and Z
  • Isobars have the same mass but different numbers of neutrons and protons.
  • Shorthand representation of isotopes

Radioactive Decay

Radiactive decay is the process by which an unstable uncleous is transformed into a stable nucleus. There may be a series of intermediate unstable nuclei as the decay/transformation process continues until a stable nuceleus is reached.

• Modes of radioactive decay
  • Beta (ß)

    Beta decay is characterized by the emission of a electron or a positron.

    A neutron decays into a proton (gain of Z), an electron (emitted) and an antineutrino

    • ß- (negative beta, negatron)
      
    • ß+ (positive beta, positron)
    • Electron capture

      An inner shell electron (K-electron) is captured by the nucleus. A proton is converted into a neutron and an electron neutrino.

      The K shell vacancy is filled from an outer shell with the generation of a characteristic x-ray or Auger electrons.

  • Alpha (α)

    An alpha decay involves the emission of a He nucleus. The Z is reduced by 2 and the mass is reduced by 4. Alpha decay usually takes place in heavier atoms with Z>82.

• Other decay processes
  • Gamma rays

    A nucleus produced by beta decay generally has an excited nucleus. The excess nucelar energy is emitted via energetic photons or γ-rays. This will reduce the nuclear energy to a ground state which is more stable. ⁶⁰Co to ⁶⁰Ni by beta emission leaves an excess energy which is emitted by two γ-rays of energy 1.17 and 1.33 MeV.

  • Internal conversion

    Internal conversion results from nuclear energy being transferred to a K-shell electron. The excess energy will cause the K-shell electron to be ejected with the excess energy - binding energy of the orbital. The vacant K-shell orbital will be filled from an outer shell with the emission of characteristic x-rays or Auger electrons.

• Decay schemes
  • Construction and interpretation
  • Examples for each decay mode


• Mathematics of radioactive decay
  • Units (SI Units)

  Quantity	Definition	SI Units	English Units	Conversion
  Exposure	X=ΔQ/Δmair	2.58x10-4C/kgair	1 R = 1 esu/cm3airSTP	1 R = 2.58x10-4C/kgair
  Absorbed Dose	D = ΔEab/Δm	1 Gy = 1 J/kg	1 rad = 100 ergs/g	1 Gy = 100 rads
  Equivalent Dose	H=Q · D	1 Sv	1 rem	1 Sv = 100 rem
  Activity	A = λN	1 Bq = 1 dps	1 Ci = 3.7 x 1010d/s	1 Ci = 3.7 x 1010 Bq

  • Exponential decay equation
    • Half-life

    A=λN

    N=N0eλkt

    T1/2=ln(2)/λ

    • Decay constant
    Mean life, average life, and effective half life

    

    Average life ( =1.44·T_1/2)

    The effective half life is the final half life of an unsealed source based on the two complementing half lives: biological elimination time and the physical decay time.

    

    
    

    
    

    ,
    

    Where λ_e is the effective half life and λ_pλ_bare the physical and biological half lifes, respectively.

    
    

    
    

    
    

    Mean life time τ is the mean time an element in a radioisotope lasts before decay.

    • Simple dose calculation for implants
  • Radioactive equilibrium

    Radioactive equilibrium describes the state of radioactivity when there are two or more competing decay processes ongoing. A parent radionuclide decays to a "transient" daughter radionuclide which may then decay further to a "transient" granddaughter radionuclide until finally a stable offspring is reached. The transiency of the intermediate decay products may be long or short relative to each other. The relative lengths of the transiency of intermediate decay products determines the type of equilibrium which will be reached.

    If the decay half life of the parent radionuclide is longer than the daughter radionuclide, then equilibrium will be attained. The ratio of parent:daughter radionuclides will approach a constant. The apparent activity of the daughter radionuclide will be governed by

    • a.) its rate of generation from the parent
    • b.) its rate of decay.
    
    

    Transient equilibrium occurs when the parent half life is slightly longer than the daughter half life. Secular equilibrium occurs when the parent half life is much longer than the daughter half life.

    The above equations describe the activity of the daughter nuclide, given the decay constants of the parent and the daughter. The maximum activity of the daughter nuclide is given by
    
    
    
    

    For λd > λp (daughter half life shorter than parent):

    For λp > λd this equation reduces to

    For λd >> λp (or daughter half life very short compared to the parent half life):

    • Secular equilibrium

      Radium decays to radon with a half life of 1602 years. Radon decays to Polonium with a half life of 3.82 days and Polonium decays to lead which is stable with a half life of 3 minutes. This is an example of secular equilibrium.

      Radium series decay table.

      • Radium needles
      • ⁹⁰Sr applicators
    • Transient equilibrium
      • Nuclear medicine generators

        Molybdenum (T_1/2=66h) decays to ^99*Tc which is used in nuclear medicine. The Mo generator decays producing Tc with a half life of 6 hours. The generator is "milked" of its Tc which is then used to prepare biologic agents used in nuclear medicine.

  • Counting statistics
• Naturally occurring radioisotopes
• Manmade radioisotopes

  Manmade isotopes are generally produced as byproducts of nuclear reactor processes. These materials are regulated in the US by the US Nuclear Regulatory Commission.

  These products are produced when a stable parent isotope is bombarded by the neutron flux (φ) in the reactor core. Each isotope has a specific neutron interaction probability, known as a cross section (σ) measured in barns ( 10^-28 m² = 10 ^-24cm²) that is a function of the neutron energy, and the nuclear composition of the parent element. There may be subsequent decay with to a granddaughter isotope upon activation.

  • Fission
  • Nuclear bombardment
• Decay schemes and properties for therapeutic isotopes

Properties and Production of Particulate and Electromagnetic Radiation

• Particulate radiation
• Mass, charge
• Relativistic energy equation
• Electromagnetic radiation
  • Wave-particle duality
  • Wave equations
  • Electromagnetic spectrum
• Production of radiation
  • Principles
  • Radioactive decay
  • X-ray tube
• Linear accelerators
  • Operational theory of wave guides
    • Standing wave guides
    • Traveling wave guides
  • Bending magnet systems
  • Flattening filters
  • Electron scattering foils
  • Electron cones
  • Targets
  • Factors affecting
    • Beam energy
    • Entrance dose
    • Depth of maximum dose
    • Beam uniformity
    • Dose rate
  • Monitor chamber
  • Collimation systems
    • Primary and secondary collimators
    • Coupled and independent jaws (including virtual wedges)
    • Multileaf collimators
    • Other collimation systems (e.g., stereotactic systems)
    • Radiation and light fields (including field size definition)
  • Mechanical and operational features
• Cyclotron
• Microtron
• Cobalt units
• Therapeutic x-ray (<300 kVp)

Interactions of Electromagnetic Radiation with Matter

• Coherent scatter
  Coherent or Rayleigh scatter is a completely elastic photon scatter. The incident photon has insufficient energy to remove an electron and the photon is scattered to a new path. Coherent scatter predominates at low energy and high Z material. The incident photons are scattered through small angles. Coherent scatter mass energy transfer coefficient is σ_R/ρ.
• Photoelectric effect
  Photoelectron effect occurs when an incoming photon has sufficient energy to eject an inner shell electron. The incident photon is completely absorbed. The inner shell vacancy is then filled by a higher orbital electron which will then release its energy either via characteristic x-ray emission or in the alternative the production of Auger electrons. The probability of a compton interaction is proportional to Z³. The probability of a photo-electron interaction is proportional to 1/E³. The angular distribution of electrons is 90° relative to the incident photon with low energy photons. The angular distribution decreases as incident photon energy increases. The photoelectric mass energy transfer coefficient is τ/ρ
• Compton effect
  Compton events are inelastic interactions with the incident photon interacting with a "free" or orbital electron. The electron is scattered, increasing its energy. Part of the photon energy is lost to the scattered electron and the photon itself is scattered. There are several possibilities of the outcome of this interaction.

  Knock on collision	This interaction is a direct hit. The knock on collision back scatters the incident photon and the electron is forward scattered. The electron in this case will recieve the maximum energy and the back-scattered photon will have minimum energy.
  Grazing Hit	The electron will be scattered at 90° and the photon will continue forward with no energy loss.
  Photon Side Scatter	The photon will scatter through 90 degrees and the electron angle will be a function of hν0/m0c2

• Pair production
• Photonuclear disintegration
• Relative probabilities of interactions in human tissues
  • Energy dependence
  • Atomic number dependence
  • Electron density dependence

Interactions of Particulate Radiation with Matter

• Formalism
  • W value
  • Specific ionization
  • Linear energy transfer
  • Range
  • Stopping power
• Types of interactions
  • Heavy vs light particles
  • Charged vs uncharged particles
  • Elastic collisions
  • Inelastic collisions
• Heavy charged particles
  • Inelastic collisions with electrons
  • Depth dose characteristics ( Bragg peak)
• Light charged particles
  • Elastic and inelastic collisions with electrons
  • Inelastic collisions with nuclei
• Neutrons
  • Elastic collisions with hydrogen nuclei
  • Depth dose characteristics vs charged particles and photons
• Biological implications of particle therapy

Quantification and Measurement of Dose (including SI units)

• Exposure (air kerma)
• Absorbed dose (kerma)
• Dose equivalent
• RBE dose
• Calculation of absorbed dose from exposure (e.g., f factor)
• Bragg-Gray cavity theory
• Gas-filled detectors
  • Principles of operation
  • Uses
• Ion chambers
  • Types
  • Exposure measurement
  • As a Bragg-Gray cavity
  • Correction factors (e.g., temperature and pressure)
  • Calibration of photon and electron beams (e.g., TG 21 and TG 25)
• Thermoluminescent dosimetry
• Calorimetry
• Film
• Chemical dosimetry
• Solid state diodes
• Scintillation detectors
• Measurement techniques

Characteristics of Photon Beams

• Mathematics of exponential attenuation
  • Half-value thickness
  • Attenuation coefficients (linear, mass, partial, total)
  • Narrow beam vs broad beam geometry
  • Monoenergetic vs heteroenergetic
  • Parallel vs diverging beams
• Beam quality for heteroenergetic beams

  X-ray beams with a few specific exceptions are composed of a more or less continuous spectrum of energy. These beams generally have a peak energy and a mean energy making them difficult to characterize directly. For kilovoltage radiation, the energy is generally specified as kVp or peak kilovoltage. A spectrum of energies ranging from zero to kVp are created by bremsstrahlung emission. This spectrum has low energy radiation that does not contribute to imaging or depth dose, but does contribute to skin dose and is frequently filtered off with copper or aluminum foils. A measure of the quality of the beam is the half value thickness of an absorber in the beam path. The half value layer is the measure of the thickness of an absorber needed to reduce the beam energy by 1/2.

  • Energy distribution of accelerated electron beam
  • Filtration
  • Geometry
  • Effective energy
  • Energy spectra

Dosimetry of Photon Beams in a Homogeneous Water Phantom

• Dose distributions
  • Central axis percent depth dose
  • Isodose curves
  • Factors affecting dose distributions and penumbra
    • Beam energy or quality (including patient dose from neutrons)
    • Source size
    • SSD and SAD
    • Mayneord F factor
    • Inverse square law
    • Field size and shape
    • Equivalent square
    • Scatter effects
    • Flattening filters
    • Depth
    • Surface dose
    • Other
  • Dose distributions for multiple unshaped beams
    • Open beams
    • Wedged beams
  • Tissue-air ratio and backscatter factor
  • Tissue-maximum ratio
  • Tissue-phantom ratio
  • Relationships between PDD, TAR, TMR, TPR
  • Point dose  and treatment time calculation methods for single unshaped fields
    • Machine output factors (e.g., absolute and relative output, head scatter, patient scatter factors)
    • Equivalent squares
    • SSD vs SAD setups
    • Beam modifier factors (e.g., wedge and tray factors)
  • Dose calculation at the isocenter of a rotating beam   
  • Point dose and treatment time calculations for single shaped fields
    • Separation and recombination of primary and scatter radiation (e.g., Clarkson techniques)
    • Off-axis factors
    • Dose under blocks
    • Equivalent squares for shaped fields
  • Isodose distributions for multiple fields, including arc therapy
  • Measurement of photon dose distributions

  Dosimetry of Photon Beams in a Patient

  • Dose specification (eg, ICRU 50)
    ICRU 50 and later ICRU 62 define target volumes for treatment planning purposes and avoidance/risk structures for minimizing dose. CTV + margin for setup uncertainty, motion

    GTV	Gross Target volume	visualizable target volume
    CTV	Clinical Target Volume	GTV + microscopic extensions
    PTV	Planning Target Volume

  • Corrections for patient contour
    • Effective SSD method
    • TAR ratio method
    • Isodose shift method
  • Corrections for tissue inhomogeneities
    • TAR ratio method
    • Power law method
    • Isodose shift method
    • Equivalent TAR
  • Dose within and around an inhomogeneity
  • Matching of adjacent fields
  • Using multiple wedged fields
  • Parallel opposed beams
    • Point of maximum dose
    • Uniformity, dependence upon
      • Energy
      • Separation
      • SSD
  • Entrance dose and exit dose, including beam modifying devices
  • Isodose distributions for multiple beams, including mixed modality and arc therapy
  • Compensation
    • Missing tissue
    • Dose compensation
    • Bolus
  • Off-axis factors
  • Practical/simple calculation of dose
  • Practical/simple 2D treatment planning
  • 3D conformal treatment planning 3D conformal treatment planning Advanced Treatment Planning for EBRT, Letter G)
  • Dose delivery accuracy and precision

  Dosimetry of Electron Beams

  • Dose distributions
    • Central axis percent depth dose
    • Isodose curves
  • Factors affecting dose distributions
    • Beam quality
    • Beam spreading systems
    • SSD and SDD
      • Effective SSD techniques
      • Inverse square
    • Field size and shape
    • X-ray contamination
    • Depth
    • Surface dose
    • Inhomogeneities (e.g., CET)
    • Other

  • Energy specification
    • Most probable energy
    • Mean energy
    • Energy at depth
    • Ranges (extrapolated, practical, R50)
  • Choice of energy and field size
  • Air gaps and oblique incidence
  • Tissue inhomogeneities
  • Bolus, absorbers, and spoilers
  • Matching adjacent fields
  • Point dose and treatment time calculations
  • Field shaping techniques
  • Electron arc
  • Total skin electron therapy

  Brachytherapy

  • Historical review—role of radium
    Radium was one of the original isotopes discovered and found to have a medical affect. Its decay sequences is ²²⁶Ra to ²²²Rn to ultimately ²⁰⁶Pb. The original definition of a Curie (Ci) was the activity of 1 gram of ²²⁶Ra. More accurate measurements have placed the curie at 0.95 g of Radium. The actual original definition of a curie based onthe original calculations remains with 1 Ci being 3.7 x 10 ¹⁰transformations (disintigrations) per second. The present SI unit is the Bequerel. The common means of specifying source strengh was in mg-Ra-eq (milligram-Radium-equivilent). This allowed clinicians to continue specifying source strength as radium equivilancy With the use of alternative sources such as ¹³⁷Cs. The conversion of source activity from mg-Ra-Eq to Ci uses the specific gamma constant Γ. Γ is defined as The Γ constant is commonly specified in units of R-cm²/mg-hr and for radium is 8.25 R-cm²/mg-hr.
    For non-Radium sources, the Γ is specified in R-cm²/mCi-hr and is used to calculate exposure at a point in space from a source with a given activity. More modern calculations use the air kerma strength, described below.
    

    Air Kerma Strength is defined as the product of the air kerma strength (in free space) x (calibration distance)². The air kerma strength is defined as S_K=K_l·l² where l is the calibration distance, normally 1 meter.

    At photon energies in commonly used brachytherapy sources the ratio μ_en/ρ / μ_tr/ρ ≈ 1 and the equation reduces to X(W/e).

    Air kerma units are μGy·m²/hr

  • Calculation of dose from a point source

    Source strength is specified in terms of air kerma, Bq, Ci or mg-Ra-Eq. From this information a dose rate can be calculated.

    The air kerma rate is based on the following conversion factor:
    D_air=X (2.58 x 10^-4 C/kg-R) (33.97 J/C) = 0.00876 J/kg = 0.876 cGy/R

  • Calculation of dose from a line source
    

    Line sources are generally calculated today by computer algorithnms. Originally, the Manchester (Patterson-Parker) system of implant dosimetry was used. The Manchester system is useful today to determine and cross-check computerized treatment plans. This system consists of a series of planar needles and optimization factors to provide for dose uniformity of ±10% excluding the corners of the implant and regions less than 0.5 cm from a source. The volume described is 5 mm above and below the needle plane and 5 mm lateral to the outermost ("rind") needles. The inner needles are referred to as "core" needles. The Manchester method assumes 1 cm needle spacing and orthognally crossed needles are placed at the ends of the planar implant. Full strength sources are used in peripherally placed (rind) needles and reduced source strengths are placed in inner (core) needles.

    Manchester System Rules

    Feature Paterson and Parker (Manchester System) Rules Dose and dose rate 6,000 R to 8,000 R in 6-8 days (1,000 R/day; 40 R/h) Dose specification criterion Effective minimum dose is 10% above the absolute minimum dose in treatment plane or volume. Dose gradient Dose in treatment volume or plane varies by no more than ±10% from stated dose except for localized hot spots.   For double-plane implants with a separation >1 cm, dose is specified on interior plane 0.5 cm from implanted plane resulting in 10% to 30% midplane cold spot. Single plane mg Ra Eq-h are multiplied by a separation factor to obtain total double-plane mg Ra Eq-h. Linear activity Variable: 0.66 and 0.33 mg Ra Eq/cm Source strength distribution: planar Area <25 cm2: 2/3 periphery; 1/3 center   25 <Area <100 cm2: 1/2 periphery; 1/2 center   Area >100 cm2: 1/3 periphery; 2/3 center Source strength distribution: volume Cylinder: belt: core: end: end = 4:2:1:1   Sphere: belt: core = 6:2   Cube: 1/8 of the activity in each face     2/8 of the activity in the core Source implant pattern and spacing between sources Constant uniform spacing: 1-cm separation between sources recommended. Smaller spacings must be used to satisfy distribution rules for small implants. Crossing needles Perpendicular to and at the active ends of the parallel needles; If placed beyond the active ends of the needles, should be double strength. Crossing needles used when possible. Planar implant: Target area effectively treated is reduced in length by 10% per uncrossed end. Volume Implant: Target volume effectively treated is reduced by 7.5% per uncrossed end. 1 uncrossed end: belt: core = 4:2:1 2 uncrossed end: belt: core = 4:2 Elongation corrections Long: short dimension: 1.5:1 2:1 2.5:1 3:1 4:1       Correction factors (applied to mg Ra Eq-h, not area or volume)   Planar 1.025 1.05 1.07 1.09 1.12   Volume 1.03 1.06 1.10 1.15 1.23 Relation between implanted volume/area and treated (target) volume/area Peripheral and crossing needles placed on the target volume boundaries. Active length determines target length. Physical and dosimetric properties of commercial sealed sources and applicators Implant instrumentation and techniques Low dose rate =dose rates less than 0.4-2.0 Gy/hr (40 cGy/hr-200 cGy/hr) High dose rate (including PDR) dose rates >12 Gy/hr (≥2 Gy/min) Ultralow dose rate (permanent implant) Dose rates < 0.3 Gy/hr (0.01-0.3 Gy/hr) Biological considerations of dose, dose rate, and fractionation Calibration and specification of sources Disseminated (unsealed sources) Acceptance testing and quality assurance Dose specification, implantation dosimetry, and dosimetry systems Patterson-Parker Quimby Paris Other Dose specification and dosimetry systems of intracavitary implants Advanced Treatment Planning for EBRT Plane radiography and fluoroscopy for simulation Portal imaging Film-based Electronic Imaging for radiation therapy planning CT MRI Ultrasound Isotope imaging Image processing Image enhancement 2D and 3D visualization of volumetric data (DRRs, volume rendering) Image registration Virtual simulation (including BEV techniques) Treatment planning systems 3D conformal treatment planning Plan evaluation (DVH, NTCP, TCP, etc) Dose optimization techniques Noncoplanar beams IMRT Radiosurgery Patient setup and alignment Quality Assurance Equipment-related Regulations and recommendations Measurement techniques Patient related Misadministration External beam Brachytherapy Brachytherapy source inventory Radiation Protection and Safety Principles, biological effect models, personnel dose limits, rules, regulations Structural shielding design for external beam therapy Primary barriers Secondary barriers Machine shielding (beam stoppers and head shielding) Neutrons Radiation protection for brachytherapy procedures Source storage and transport containers Patient room Special considerations for high dose rate brachytherapy Special procedures and source prep rooms Release of patients treated with temporary implants Leak testing of sealed sources Routine radiation surveys Personnel monitoring Protection against nonionizing radiation Administrative requirements Radiation Safety Officer Radiation Safety Committee Safety instructions and safety precautions Sealed-source brachytherapy Radiopharmaceutical therapy Quality Management Program Written directive Identification of patient Plan and delivery in accordance with written directive Unintended deviation Recordable events Misadministrations Special Topics Hyperthermia Computers .Return to top of page