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Hot and cold spots are common problems associated with planning:

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Presentation on theme: "Hot and cold spots are common problems associated with planning:"— Presentation transcript:

1 Hot and cold spots are common problems associated with planning:
A. Isocentric Fields B. Four Field Technique C. Three Field Technique D. Abutting Fields

2 D.

3 Central axis depth dose distribution depends on energy
Central axis depth dose distribution depends on energy. Which of the following is true? Depth of a given isodose curve increases with beam energy Absorbed dose outside primary beam is greater for higher energies An advantage of orthovoltage is increased energy of scatter radiation A B C D. 1,2,3

4 A.

5 Why does exposure rate increase as field size increases?
Filter flattening Block transmission Collimator scatter Phantom scatter

6 C.

7 The depth of maximum ionization is most dependent on:
SSD Field Size Beam Energy Thickness of tissue

8 C.

9 All of the following are general properties of x and gamma ray dose distribution EXCEPT:
Near beam edge dose rate decreases rapidly Near beam edge fall off is due to geometric penumbra and side scatter Dose at any depth decreases toward edges Dose at any depth is lowest on central axis

10 D.

11 When verifying an isodose chart using a water phantom, the acceptable amount of deviation is considered to be ___ or less in depth up to 20cm 2% 4% 7% 10%

12 A.

13 Because of its relatively flat energy response and higher precision, the most reliabel isodose charts are measured by a/an TLD Ion Chamber Radiographic Film Laser Beam

14 B.

15 A 3-D compensator was constructed for a patient
A 3-D compensator was constructed for a patient. The Oncologist added 3cm to the width. What do you do? Hand block and treat Construct a new compensator Move the compensator 3cm and treat Do not change anything and continue treatment

16 B.

17 Which of the following will not effect the isodose curve?
Bolus Lucite Tray Compensator

18 B.

19 The angle between the central axes of two beams is called the:
Hinge angle Wedge angle Seperation angle Plateau angle

20 A.

21 The wedge used during external beam irradiation of the larynx is used to:
Evenly distribute dose Increase distributed dose Reduce skin dose Reduce backscattering

22 A.

23 What is the hinge angle for a 30 degree wedge?
60 100 120 150

24 C.

25 An area outside the target area which receive a higher dose than the specified target dose is called a Tolerance spot Cold spot Hot spot Threshold spot

26 Two treatment fields on a patient have a hinge angle of 90 degrees
Two treatment fields on a patient have a hinge angle of 90 degrees. What is the wedge angle 15 60 45 30

27 C.

28 The ______of a beam refers to the sameness from side to side of the profile
Flatness Symmetry Dosimetry Bolus

29 B.

30 _______ is the measurement of radiation dose
Dosimetry Physics Dose Prescription

31 A.

32 The use of half beam technique has the advantage of:
Avoiding areas of increased dose Increasing number of hot spots Preventing beam divergences Decreasing number of cold spots

33 C.

34 A _____ isodose curve will have an hour glass shape of the highest intensity isodose line
POP 4 Field Box 3 Field 4 Field Diamond

35 A.

36 A_____ is the use of independent variable jaws moving during the treatment.
Wedge pair Universal wedge Dynamic wedge Hinge angle

37 C.

38 Stereotactic is a type of:
Non-coplanar beam Co-planar beam Wedged beam Vertex field

39 A.

40 Which method decreases dose at sides of patients?
POP 4 Field Box 4 Field Diamond 3 Field None

41 C.

42 A ________ uses more than 4 fields with extensive blocking
Dynamic Field Conformal Field POP None of these

43 B.

44 The area of the isodose curve close to dmax that appears uneven is the ?

45 Horns

46 Adjustments to the dose distributions can be accomplished by assigning different _____ to the beams

47 Weighting

48 Beam symmetry must be within ____ from side to side over _____ of the beam at _____cm depth
3%, 75%, 100 2%, 80%, 10 5%, 80%, 5 10%, 80, 10

49 B.

50 The process of converting dose distribution to percent of a dose at some point is called:
Field Weighting Normalization Bolus None of these

51 B.

52 The depth of maximum ionization if most dependent on A. SSD B
The depth of maximum ionization if most dependent on A. SSD B. Dose per fraction C. X-Ray energy D. Total Dose

53 C.

54 The treatment prescription should define the:
Treatment volume Tumor Dose Number of treatments 1, 2 2, 3 3, 1 1, 2 and 3

55 D.

56 Mayneord f-factor is of use when there is a change in _____
A. PDD B. SSD C. Energy D. TA

57 A.

58 This is an example of a/an:

59 Isodose Curve

60 Name the beam energy A B C

61 Co-60 6MV 18MV


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