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Which of the following describes where the field size is defined in a non-isocentric approach?

A patient is treated on the 6 MV linear accelerator treatment machine at 100 cm SAD.  The treatment SSD is 90 cm.  The prescription states that a dose of 4000 cGy is to be delivered to a depth of 10 cm in 20 fractions with an AP/PA treatment field arrangement.  If the patient’s spinal cord lies at a depth of 6 cm beneath the patient’s posterior skin surface, what is the depth to the spinal cord from the anterior skin surface?

Which of the following best describes the distance between the entrance and exit points?

When multiple MV photon beams are used, the dose at Dmax  is normally

2 posterior spine fields are required to treat a patient.  They are treated with 6 MV and to a depth of 7 cm.  One field measures 8 x 23 cm at 112 SSD.  Another field measures 8 x 19 cm at 110 SSD.  What is the required gap needed for this treatment?

Which of the following are considered when designing fields and beam arrangements?  (Select all that apply)

Calculate the percentage of the dose attenuated if the measured dose with the wedge is 95 cGy and the dose without the wedge is 125 cGy.

A patient is 24 cm thick.  You are to treat right and left  laterals and give 3600 cGy to midline weighted 2:1 respectively.  the PDD for a depth of 12 cm is .621.  What is the given dose to the left side?

Which of the following represents the relationship between the dose and the PDD at a point?

A patient’s prescription requires a total of 180 cGy to be delivered per day to equally weighted to POP fields (Parallel Opposed Ports).  The treatment time to deliver 100 cGy is 2.15 minutes.  What treatment time must be delivered to each field to follow the prescription?