HEALS: Treatment Planning & Dosimetry

  1. Which of the following areas should be included when irradiating a tumor of the nasopharynx?
    I. nasopharynx proper
    II. retropharyngeal nodes
    III. base of the skull
    • All of the above
    • Image Upload 1
  2. During a treatment calling for a tangential beam with a steep grazing incidence, the surface dose build-up is _________ (equal/not equal) to the entrance dose.
  3. All of the following areas require the treatment of the surrounding lymphatics, EXCEPT for the T1 - T2 tumors involving the:

    A. Larynx
  4. The amount of geometric penumbra is NOT effected by the:

    B. Field size
  5. The rational behind using lower than 100% isodose curve for irradiation of the chest wall using an electron beam is:
    1. increased skin sparing
    2. lower lung exposure
    3. reduced bolus use
    2. Lower lung exposure
  6. Ultrasound provides useful information for patient contours of the following structures, EXCEPT:

    A. Lung tissue
  7. A wedge pair technique may effectively treat to a tumor depth of:
    0-7 cm
  8. When a wedge pair technique is used, an acceptable value for a high dose region (hot spot) would be _____%.
  9. "Negative" shield blocks are more commonly used for treating tumors of the:

    C. head & neck
  10. During a 4 mV treatment, a sloping skin surface is corrected by a ________ shift toward the skin surface of the isodose curve.
  11. The ICRU considers the minimum accuracy of the delivered dose to be ____% of the prescribed dose.
  12. The caudal margin of the target volume in patients with endometrial cancer is:

    D. mid-obturator foramen
  13. During rotation therapies with an arc angle of 100°, the point of maximum dose is normally located displaced ________ (toward/away from) the irradiated sector.
  14. Tumors that are limited to the upper cervical esophagus are best treated with:

    C. Three field technique with posterior obliques
  15. A half value layer thickness for a 10 MeV photon energy is about ______ mm Pb.
    13 mm Pb
  16. What is the formula used to find Dmax from percentage depth dose?
    Image Upload 2
  17. The 6 field Stanford technique is most often applied to:

    A. cutaneous lymphoma
  18. During XRT of a pituitary tumor with the patient supine, the anterior field should enter:

    A. above & behind the eyes
  19. The target volume for carcinoma of the prostate may include the following regional lymph nodes:
    I. Obturator
    II. External iliac
    III. Internal iliac
    All of the above
  20. A treatment designed to be given at 120 cm SSD is mistakenly given at 100 cm SSD. What is the error in dose delivered? 

    B. 44% overdose
  21. In treatment of the mediastinum, following a right lung pneumonectomy, the oblique field should enter on the _________ (right/left) side.
    Right side
  22. The principle concern in localizations of breast lesions is the:

    C. position of underlying lung
  23. Radiotherapy is most often indicated for carcinoma of the __________ portion of the esophagus.

    A. upper
  24. During a radiotherapy of the uterus using a 4 field box technique, which field includes the entire urinary bladder?
    1. anterior  2. posterior  3. lateral

    • C. 2 & 3
    • Posterior & lateral
  25. During XRT of the esophagus, rotational and arc therapy is usually NOT possible because of the:
    1. heart movement 2. spinal curvature 3. position of the esophagus

    • A. 2 & 3
    • curvature of the spine and position of the esophagus
  26. The AP/PA "stop sign" field is most often used in the treatment of:
    Prostate ca
  27. In order to include the hypogastric nodes in a lateral field of the pelvis, the posterior margin should transect the:

    A. rectum
  28. The TAR at Dmax is:
    1. always less than or equal to 0
    2. the backscatter factor
    3. dependent on field size

    A. all of the above
  29. An increase in field size will increase dose in the ______ region.
  30. The Maynoerd F factor for a given energy is dependent upon material's:

    A. atomic number
  31. The energy range for photon beams above 2 MeV should be measured by:

    A. isodose data
  32. The amount of backscattering that occurs in a given treatment volume will increase as the: 
    1. field size increases 2. beam quality increases 3. Dmax increases

    C. field size increases
  33. The amount of backscatter at the depth of the depth maximum becomes negligibly small at beam energies above:

    B. 8 mV
  34. The scatter-air ratio (SAR) may be used in the determination of the scattered dose produced in:
    1. square fields 2. irregular fields 3. circular fields

    A. all of the above
  35. An isodose curve can be employed to obtain measurements of the depth dose percentage as a function of the transverse distance from the:

    A. central axis
  36. When verifying an isodose chart using a water phantom, the acceptable amount of deviation is considered to be ______ or less in depth up to 20 cm.

    B. 2%
  37. Calculate the Dmax dose for a patient receiving 300 cGy/day for a single AP port to a depth of 8 cm. The PDD is 69.3%
    432 cGy

    Image Upload 3
  38. The backscatter factor (BSF) depends on:
    1. SSD 2. Beam quality 3. Field size

    A. Beam quality and Field size
  39. The Clarkson method is useful in the determination of the scatter produced in __________ fields.
    Irregular fields
  40. The ratio of dose at a given point in a medium to the dose at the same point in free space is called the:

    C. tissue-air ratio (TAR)
  41. Central axis depth dose distribution depends on beam energy, so the depth of a given isodose curve ________ (increases/decreases) with beam energy.
  42. A bulge on the lateral region of the isodose curve at depth is most often associated with:

    D. low energy beams
  43. The sharpness of a shielding block gradient is dependent upon:
    1. beam energy 2. block material 3. block divergence

    C. Beam energy & Block divergence
  44. The reduction of block transmission penumbra can be accomplished by:

    C. employing divergent blocks
  45. In general, when shielding blocks are employed, the acceptable amount of primary beam transmission is approximately:

    C. 5%
  46. During a wedge pair technique, hot spots are most commonly located near the:

    C. thin edge of the wedge
  47. Which of the following devices is employed to help obtain proper alignment of a treatment beam?

    C. front/back pointer
  48. The material most suitable for the reduction of electron contamination in megavoltage units is:

    B. tin
  49. The minimum thickness for blocks for a Cobalt 60 machine is:

    D. 5 cm lead
  50. Which of the following block designs permits the longest SSD?

    B. divergent blocks
  51. In order to produce the least amount of electron contamination from a shadow tray, the material should have a atomic number of about:

    C. 50
  52. In order to achieve a 5% or smaller block transmission, it must have a thickness of about:

    D. 5.0 HVL
  53. The required thickness for a cerrobend block for a narrow photon beam in the 2-22 mV range is about:

    D. 7.5 cm
  54. The main advantage of using Lipowitz metal over lead for blocks is that it:

    A. Has a lower melting point
  55. The tissue most likely to receive the highest dose at a bone tissue interface is bone mineral surrounded by __________.
    Soft tissue
Card Set
HEALS: Treatment Planning & Dosimetry
HEALS: Treatment Planning & Dosimetry Chapters 10-13