Treatment planning Test 2(no ct images)

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Treatment planning Test 2(no ct images)
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2013-10-27 15:27:48
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Treatment planning Test 2(no ct images)
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  1. When a linear accelerator with one independently moving leaf is used with a wedge in the beam, there is a chance that the independent jaw cannot be used because...
    The COLLIMATOR may have to be turned in a direction such that the independent jaw cannot be used
  2. The attenuation if Cerrobend is about ___% (less than/ greater) than lead.
    Cerrobend attenuates 15% less than lead
  3. The potential hazards of working in the mold room where alloy shields are made consist of-(list 4)
    • 1) inhalation of vapors and dust particles
    • 2)ingestion of small fragments of the metal
    • 3)skin penetration
    • 4)burns
  4. To reduce the risks of ingestion fragments of the alloy in the block room, the following precautions should be taken-
    Practice good hand hygiene before eating, drinking and smoking
  5. Multilevel collimators are different from custom shaped blocks because-
    The produce step like edges, leakage can occur between leaves, and they can only be used with limited field sizes
  6. Custom made electron locks are different from custom blocks for photon beams because -
    They have NO FOCUSED EDGE and are much thinner; also, the size of of the opening is practically the same as the field on the skin surface.
  7. When a skin lesion is treated using an electron or orthovoltage beam, the shielding -
    Should be placed directly on the patient, covering a large area surrounding the lesion
  8. Secondary scatter in the tissue-metal interface can cause____ dose in the adjacent tissues but can be ______by.....
    • High
    • reduced 
    • placing 2-4mm of tissue equivalent  material over the teeth
  9. When a lip lesion is treated, it is possible to reduce mucosal reaction by
    Placing an internal shield distal to the tumor and covering the shield with a coating of wax
  10. When a missing tissue compensator is used in a photon beam, the compensator should be placed....
    At some distance from the skin surface.
  11. The most practical material to use when making a compensator for a photon beam is(name 5)
    (NOT LEAD or other higH Z materials!)

    • 1)Wax
    • 2)paraffin
    • 3)Lucite
    • 4)brass(like DOT DECIMAL)
    • 5)aluminum
  12. Bolus material is used to
    Reduce the depth of maximum dose when PHOTON beam is used

    ????doesn't it do the same for an electron beam or is it just used for surface irregularities?????
  13. The function of the Radiologic Physics Center(RPC) is to
    • Review patient treatment records, Dosimetry calibration of equipment use in treatment of patients enrolled in clinical trials, and communicate instructive findings to the clinical study groups.
    • *Note- even though the RPC is for QA for CLINICAL TRIALS, it has a spillover effect towards ALL treatments.
  14. Departmental weekly chart rounds should include verifying( name 6 things )
    • 1)presence of diagnoses
    • 2) histology
    • 3)stage
    • 4) presence of consent to treatment
    • 5)presence of pathology report
    • 6) evidence that patient is making progress
  15. The frequency of port films varies, but they
    Should always be taken on the first day of treatment
  16. Electronic portal imaging is a method whereby the patient/beam alignment is checked
    after only a few MU have been delivered
  17. Various methods of documenting the treatment parameters include( list 3)
    • 1)tattoo
    • 2) photograph of each treatment field
    • 3)port film of treatment field

    ???Ask about difference between port film and "isos"??????
  18. If a 30 degree wedge is left out of the treatment during 1-5 treatments,
    the central axis dose is increased and the isodose curve is affected

    *the MOST IMPORTANT Thomas g is when a mistake is discovered to REPORT it to the PHYSICIAN so that he can decide if adjustments are needed
  19. When an error in dose delivery is discovered
    THE ATTENDING RADIATION ONCOLOGIST SHOULD BE NOTIFIED
  20. Treatment fields should be labeled in the chart with reference to......
    An anatomical description, and it should have a unique number
  21. The angle of beam divergence is
    Larger farther from the central axis
  22. When parallel opposed fields are used and the isocenter  is at mid depth in the chest, the length of the spinal cord is
    Longer on the anterior field than the posterior
  23. When parallel opposed fields are used and the isocenter  is at mid depth in the chest, the
    The anterior  port film should appear exactly as the anterior sim film with respect to anatomy
  24. The size of the magnification device is important because a ______ device is more likely to lead to errors in the magnification factor
    SMALL
  25. A circular magnification device, which is 5 cm in diameter, is placed on the patient's anterior surface where the SSD is 100 cm. the sim film is at 135 cm from the target(TFD). The magnification factor is
    135/100=1.35 mag factor

    TFD/SSD

    • 5x 1.35=6.75 cm
  26. A 3D coordinate system is used in RT to describe a point in the patient in respect to the origin. +2 cm on the Y-axis would be  located
    2 cm cephelad to the origin
  27. The most commonly used beam energy to treat head and neck cancer is
    • Cobalt-60
    • 4-MV and 6-MV photons
  28. The following techniques can be used to deliver a boost dose in the treatment of carcinoma of the base of the tongue
    small external beam fields or an interstitial implant
  29. The majority of cancer in the head and neck region is
    squamous cell carcinoma
  30. A bite block is sometimes inserted between a patient's teeth because
    It help's the patient keep his or her mouth open during the treatment so more of the oral mucosa can be excluded from the radiation field
  31. To make patients more comfortable during treatment, it is a good idea to
    provide supports under head, knees, and arms
  32. Xerostomia is caused by irradiation to the
    • salivary glands
  33. The functions of the saliva are to
    • 1)Moisten food
    • 2)promote swallowing
    • 3)prevent tooth decay
  34. In the treatment of head and neck cancer, immobilization is particularly important because
    • 1)the proximity of several radiosensitive organs
    • 2)often small tumor margins
  35. When carcinoma of the oropharynx is treated, the field junction between opposed lateral and an inferior border should be set-
    Cephalad to the thyroid notch

    *In book it says to match AT the thyroid notch
  36. When a patient, immobilized in the supine position, is treated for Graves' opthalmopathy, half-beam blocked opposed lateral fields centered on the lateral canthus are usually used. Both lenses of the eyes are excluded from the beam when rotating the gantry to
    An angle when both lead markers placed on the eyelids of the closed eyes are superimposed
  37. To place a large patient so the head is in the neutral positition
    a high support is needed under the head
  38. To include the entire maxillary antrum without also including the eye when a patient is treated for a maxillary antrum tumor
    The chin is extended and the head tilted back
  39. To avoid overlap between the opposed lateral and anterior fields used in treatment of head and neck cancer
    A full-length midline block can be used over the spinal cord in the anterior fields
  40. The junction between the lateral and the anterior fields is chosen so that, when a full-length midline block is used, the larynx is also blocked in an effort to
    avoid laryngitis
  41. Prior to starting the treatment of boost fields, it is good idea to take port films because
    skin and seed markers may have shifted and margins are small
  42. When the boost field is given and the central axis is moved the dose in the midplane on the central axis of the boost fields is added to the dose received at the ________from the previous fields.
    same point
  43. When the true vocal chords tumors are treated
    • A 15 or 30 wedge is often used, but the dose in the anterior commissure could be compromised.
  44. Early vocal cord cancers with normal cord motility are cured by radiation therapy alone in about ______% of cases.
    • 90%
  45. Retinoblastoma is a tumor of the eye that usually occurs in _________.
    small children
  46. Parotid tumors are often treated using
    mixed electron and photon fields

  47. The most common of all intracranial malignancies is
    metastatic disease

    *remember to be careful how this question is asked... If it asks what is the most common PRIMARY brain tumor the answer would be GLIOMAS
  48. A stereotactic frame is intended for use in(single/multiple) fraction treatments.
    single fraction

    • Leksell stereotactic frame
  49. When adjacent fields are matched, it is more important to
    Match the fields precisely during a GIVEN treatment than reproduce the LOCATION

    *In other words, the fields might move slighty but they always need to be MATCHED PRECISELY
  50. To appreciate the position of the eyes relative to the beam
    A radiopaque marker is placed on the lateral canthus of each eye

  51. Dose heterogeneities within the brain when parallel opposed fields are used
    are increased when lower energy photon beam is used

    *However, when higher energy beams are used then the lateral aspect of the brain is compromised
  52. The vertex field is difficult to treat because
    there is no way to obtain a port film

    *couch is kicked 90 degree(along with gantry)make it possible to have beam vertex(come in through top of head) but then there is no place to put port film(and flat panel can not be raised into table or in the middle of the body)
  53. To minimize the beam divergence into the eye on the opposite side, when treating a brain through opposed lateral fields
    the beam is centered on the lateral canthus of the eye

    *Block for anterior portion of eye, beam anlged posteriorly
  54. When the entire spinal axis must be treated, the patient's posterior surface should be as flat as possible in order to
    make the dose more uniform
  55. Lateral brain fields and a posterior spinal field are matched by
    • rotating the collimator and rotating the couch when treating lateral fields

    *
  56. To trace the tumor volume onto a lateral sim film, a sagittally reconstructed CT or MRI image of the patient's head
    CANNOT be used because they may not represent the midsaggital plane
  57. When a 3-field technique(vertex and opposed lateral) is used to treat pituitary lesion
    Wedges are used in the lateral fields
  58. When 6-MV photon beam is used in a 180 degree arc technique to treat a pituitary lesion
    a wedge is used a reversed midway in the arc
  59. The disadvantage of a vertex field is that
    it often exits in the pharynx and spinal cord

    *also inability to take port film
  60. Field gaps are often shifted 2-3 times during a course of treatment to
    • to reduce the risk of overdosage in the spinal cord

    *Clinical Endocrine Oncology edited by Ian D. Hay, John A. H. Wass
  61. When the lateral cranial fields are treated and the couch is turned to facilitate the gap with the posterior spinal field then the SSD becomes(shorter/longer)in the ________spine segment when both lateral fields are treated.
    • the cervical spine section SSD becomes SHORTER
    • *

    *Leibel and Phillips Textbook of Radiation Oncology: Expert Consult By Richard Hoppe, Theodore L. Phillips, Mack Roach III
  62. The typical CSI setup, to avoid having the caudal margin of the lateral brain fields diverge into the cephalad aspect of the posterior spinal fields, the foot of the couch is turned
    In towards the collimator

  63. To determine depth of the spinal cord
    Measure the depth on a lateral radiograph with a lead wire over spine
  64. Of all childhood tumors, medullablastoma represents____%
    20%
  65. Symptoms or myelopathy are (reversible/irreversible)
    IRREVERSIBLE
  66. The most commonly occurring cancer in the United States is
    lung cancer
  67. When an immobilization device is needed, it is best to first determine the _______, and then________.
    first determine beam orientation THEN build the device
  68. It is important to reproduce the patient's position as it was during________.
    the simulation procedure
  69. Opposed anterior and posterior fields in the chest invariably cause a (higher/lower?) dose near the (cephalad/caudal) margin of than at the ______.
    higher dose near the cephalad margin of the CAX
  70. A lung boost is often delivered via_____
    opposed oblique fields
  71. Treatment fields in the chest should be designed with_______in mind.
    respiratory motion
  72. Tumors in the lower 2/3 of the esophagus can be boosted via_________
    An anterior and two posterior obliques
  73. Aligning two points separated by a long distance (is/is not?) a reliable method to reproduce a patient's position.
    Is a reliable method
  74. In setting up opposed oblique fields to treat a lung tumor it is important to know_______.
    The SSD for each field
  75. The number of US women who will develop breast cancer is approximately one in ______.
    1/10
  76. The regional lymph nodes in breast cancer are:
    • internal mammary
    • supraclavicular
    • axillary
  77. In most breast treatment techniques, field matching is a problem between:
    • Between the internal mammary and the tangential field
    • Between the tangential and the supraclavicular fields

  78. The couch angle necessary to avoid bean divergence from the tangential fields into the SCV field depends on the(list 2 things)
    • 1)length of the tangential field in the direction of the SCV field
    • 2)distance
    • *Use Heinz-57 formula
  79. To avoid beam divergence into the tangential fields into the SCV field the (foot/head) of the couch is turned(towards/away) from the collimator(gantry).
    foot of couch is turned AWAY from the collimator
  80. To avoid beam divergence into the lung by tangential fields the CAXs can be separated by slightly(more/less?) than _______degrees.
    separated by slightly MORE than 180 degrees

  81. Multiple adjacent electron fields to treat a chest wall recurrence should be considered ONLY if _______is available.
    proper dosimetry
  82. A boost is sometimes delivered to the tumor bed in breast cancer using
    • an electron beam or an interstitial implant
    • (also Accuboost)
  83. Cardiac toxicity from breast irradiation is __________.
    sometimes a serious problem
  84. The internal mammary nodes are sometimes treated in a separate field using an electron or photon beam or are_______;
    included in the tangential fields
  85. The most important considerations to avoid radiation-induced pneumonitis is(name 3):
    • 10total dose
    • 2)fractionation schedule
    • 3)volume of irradiated lung
  86. What should be contoured?
    • external surface
    • target
    • OAR
  87. Multiple level contours show what?
    Change in separation along the proposed treatment area
  88. Besides using a CT based treatment planning software how can a patient's external surface be contoured?
    plaster of paris
  89. How is the field contoured?
    • 1) contoured CAX
    • 2)1 cm below superior border(sup -1cm)
    • 3)1 cm above inferior border(inferior -1cm)
  90. Why is field placement so important?
    • see pg 185(more to follow!)
    • to avoid missing target and irradiating dose limiting structures
  91. How often are lasers checked?
    every AM
  92. Where are the lasers placed for a whole brain?
    bony canthus
  93. What is failure of localization?
    failure to determine the extent of the disease
  94. What happens when patient is not positioned correctly?
    The treatment field is displaced compared to intended position.(that's why we take port films)
  95. How much is the tumor margin(usually?)?
    • most fields include a margin of 0.5 cm(5mm)
    • the PTV has 1.5 cm
  96. Why is the patient immobilized?
    for REPRODUCIBILITY
  97. What is a beam modifier why is it needed?
    • A beam modifier blocks critical structures
    • A FBL is a focus block has attenuation 15% less than PB
    • Photon blocks have 5HVL

    BEAM MODIFIER CHANGES THE SHAPE OF THE FIELD
  98. What is a photon block cutter called?
    A Heuster block cutter
  99. What is the makeup of Cerrobend?
    BLT with Cheese

    • 1)Bismuth(50%)
    • 2)Lead(26.7%)
    • 3)Tin(13.3%)
    • 4)Cadmium(10%)
  100. What is an internal shield and where is it used?
    • It is used in the mouth because photons interact with teeth causing secondary electron scatter
    • Seconday electron scatter can cause high dose in the tissue/metal interface and cause ulcers in the mouth
    • Gauze in the ear is another internal shied to eliminate electron scatter
  101. What is a tissue compensator?
    A tissue compensator compensates for "missing tissue" which are caused by irregularities in the patient's surface

    *Only used for photons
  102. What is QA and what does it included?(generally)
    Quality assurance is written policies(or rules) and procedures(steps to follow) which are done daily, weekly, monthly, etc.

    • Chart rounds are an example of QA
    • Verifying patient name and birthdate

    *A misadministration leads to new policies and procedures
  103. What are tattoos for?
    • 1)They locate previous tx field(so we don't overlap fields and over-treat)
    • 2)locate current treatment field

    *Before tattooing a patient be sure to ask them if it is okay after explaining the purpose of the tattoo(VERBAL CONSENT)
  104. What is and EPID?
    Electronic Portal Imaging Device


    • i.e. the "flat panel"
    • On board imaging
  105. What is a record and verify system?
    It is a system in the computer that confirms and records everything from data acquired from the VB on first day.(gantry angles, wedges,MUs, xyz)
  106. How much must a mistreat be before the doctor is notified? The state?
    • Doctor is ALWAYS notified when there is a mistreat.
    • State is notified when it is more than 20%
  107. What are the three methods of shielding?
    • 1)LESS time
    • 2)MORE shielding
    • 3)MORE distance
  108. Define PDD
    • Percentage Depth Dose
    • Dose at depth/Dose at dmax x 100%

    The ratio of absorbed dose at a specified depth to the absorbed dose at dmax expressed as a percentage
  109. What does ARRT, R.T. (T) stand for?
    The American Registry of Radiologic Technologists, Registered Technologist in Radiation Therapy
  110. 1 Gy =______J/kg
    1
  111. 1 cGy =_____J/kg
    • .01
    • (NOT 100!!!)
  112. 4500 cGy =_____Gy
    45 Gy
  113. 1.8 Gy =____cGy
    .018  cGy
  114. 90 cGy =_____Gy
    0.90 Gy
  115. When is Mayneord's F Factor used?
    Mayneord F Factor is used to calculate the change in PDD for a treatment with an extended distance.
    *PHOTON ONLY

    (PDD2+dmax/PDD1+dmax)2 x (PDD1+d/PDD2+d)2

    21, 12 dmax before depth

    • ***used to correct for depth dose at an SSD other than 100cm for SSD type set ups.
    • MF = [(f₂+dmax)/(f₁+dmax)]²⋅[(f₁+d)/(f₂+d)]²
    • and then DD = DD₀ x MF
    • REMEMBER MAYNEORD'S IS FOR FINDING THE NEW PDD WHEN THE SSD IS CHANGED-USE THE FACTOR TO MULTIPLY BY THE OLD PDD TO GET THE NEW PDD












  116. What are the limitations of an isodose chart(list 3)
    • 1)represent dose distribution in only one plane
    • 2)are only for square or rectangular fields
    • 3)depict dose distribution from only one field
  117. What is a single field typically used to treat?
    • electrons
    • T-spine
    • L-spine
  118. When the tumor si not situated at mid-depth , it is usually beneficial to deliver a(higher/lower) dose from the field wherethe tumor is shallower.
    This is called______the beam.
    • Higher dose from the side where tumor is shallower
    • WEIGHTING
  119. WHAT IS DOSE NORMALIZATION?
    It is the dose at some point that has been forced to 1)00%.

    MU(of 100% ISL)/ISL(of volume covered)

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