Brain Teaser #16

A) Question:

The most common symptom for esophageal cancer is?

A) Answer:

Dysphagia is the most common symptom for esophageal cancer (trouble swallowing).

B) Question:

What condition is most commonly associated with adenocarcinoma of the esophagus?

B) Answer:

Barrett's esophagus is the most common condition associated with adenocarcinoma.

C) Question:

If an esophageal tumor measures 2.5 cm, and central axis is directly centred in the tumor, what would you expect the minimum field length to be?

C) Answer:

You would expect the minimum length to be 12.5 cm in length for the field size.

Follow Up:

The minimum length would be 2.5 cm of tumor plus a minimum of 5.0 cm superior of the tumor and 5.0 cm inferior of the tumor.

5.0 + 5.0 + 2.5 = 12.5 cm

please note, some doctors may treat more in length depending on the disease, but usually 5.0 cm is the minimum.

D) Question:

The lower 1/3 of the esophagus has the majority of incidence of what cell type?

D) Answer:

The lower 1/3 of the esophagus has the majority of incidence of adenocarcinoma.

E) Question:

The average length of the esophagus is?

E) Answer:

The average length for the esophagus is 25 cm.

F) Question:

In lieu of a compensator, for a patient with a highly sloped chest, what could be used to compensate for the missing tissue?

F) Answer:

A wedge could be used as to compensate for the missing tissue.

G) Question:

For a patient with a sloped chest, in which orientation would you expect the heel to be oriented?

G) Answer:

If a wedge is used on the chest, you would expect the heel to be superior to make up for the missing tissue.

H) Question:

On the AP field, you forgot to put in the wedge. The calculation was done with the wedge factor included. The wedge factor was .703 and the dose that was suppose to be given was 75 cGy for that field. By leaving the wedge out, how much dose did you really give?

H) Answer:

If you were suppose to give 75 cGy, and the wedge factor was .703, and the wedge was left out, then 107 cGy would have been delivered instead.

Follow Up:

Simply take 75 cGy dived by the wedge factor of .703, and this will give you the dose delevired.

75 cGy
---------------------------------------------------------- = 107 cGy

I) Question:

If 107 cGy was given instead of 75 cGy, what was your percent error for this field?

I) Answer:

The percent error would be 43% for that one field.

Follow Up:

--------------------------------------------- X100

75 cGy -107 cGy
--------------------------------------------- X100
75 cGy

In this case the 75 cGy is your expected, or what you were suppose to deliever, and the 107 was the actual, what you really delivered. Which is a difference of 43%


Author: Adam Buell
Co-Author: Deb Zehel
Editors: Mary Hare
Date Created: March 2006