Module 3

Unit 4: Quiz

Instructions: Answer the multiple choice questions below, then click on the "Process Questions" button at the end of the quiz to see your score in the adjacent message box. The program will not reveal which questions you answered incorrectly, only how many points you have. Go back and change your answers until you get them all right. (At that point the page frame will change to pink.)

Points to note: (1) Questions with one or more possible answers give a point for each correct answer, but also subtract a point for each wrong answer! (2) The program will not attempt to score your efforts at all if you have not tried at least half of the questions. (3) This quiz is for your own use only. No record of your progress is kept or reported to anyone.

1. A direct or differential DVH...
...gives spatial information of the dose distribution in a given structure. 
...is a plot of the (percentage) volume receiving a dose within a specified dose interval as a      function of the dose. 
...shows the extent of the dose variation within a given structure. 
...directly shows the absolute dose received by a given structure. 
2. A cumulative DVH...
...comprises no spatial information. 
...is a plot of the (percentage) volume of a given structure receiving at least a given dose as      a function of this given dose. 
...is a plot which starts at 100% of the volume for 0 Gy. 
...is a plot which ends at 0% of the volume for the prescribed or tolerance dose. 
3. For multi-leaf collimators some leaf positions are not valid due to leaf constraints. Depending on the LINAC, such leaf constraints may be, e.g. Maximum leaf overtravel, minimum leaf gap or interdigitation (see illustrations below).

      

Figure 1: Examples for MLC leaf constraints: maximum leaf overtravel (upper line, left), minimum leaf gap (upper line, right) and interdigitation (lower line)

If there was an invalid leaf position in your plan and the treatment planning system would ask you to change this position, what should you do? 
Accept the change and go back to recalculate the plan and redo the plan evaluation.
Accept the change and transfer the plan. 
Transfer the plan without accepting the changes. 
4. Below two DVHs for the same PTV are shown. Which of these two DVHs results in a better tumour control probability (TCP)?

A


B
A 
B 
equal
5. Which of the following statements about biological models are true?
Should not be used as the only criteria for treatment plan evaluation. 
Can help to decide between two possible treatment plans. 
Are of stochastic nature and can therefore vary from on calculation to another for exactly      the same plan. 
6. Which are the drawbacks of dose statistics?
There is no information about dose distributions. 
There is only information about doses to the PTV but no information about doses to OARs. 
There is no spatial information. 
The minimum dose is calculated, but there is no information on how many voxel receive this      dose. 

      Points out of 13:

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This consummately cool, pedagogically compelling, self-correcting,
multiple-choice quiz was produced automatically from
a simple text file of questions using D.K. Jordan's
dubiously original, but publicly accessible
Think Again Quiz Maker
of October 6, 2008.

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