Radiation Oncology

Question 1

What is a lethal volume of cancer and how does it compare to a detectable level of cancer

Answer 1

Lethal volume= 1x10^12 cells (1kg)
Lower limit of detection is 1x10^9

Most cancers have completed 2/3rd of their natural lifespan before the are detectable

Question 2

Why is radiation given in conjunction with a lumpectomy?

Answer 2

To reduce the rate of recurrance

Question 3

Do you ever give chemo and radiation at the same time?

Answer 3

Yes- improves cancer control rates

Problem: increased toxicity

Question 4

Where do local breast cancer recurrences occur?

Answer 4

90% local recurrences are in the index quadrant independent of applied radiotherapy

Question 5

Name three factors for reducing exposure to radiation

Answer 5

Time
Exposure
Shielding

Question 6

When can radiation therapy be done relative to surgery?

Answer 6

Before, after or in combo with chemo. Basically whenever

Question 7

What is the most important factor for determining if a patient is having radiation toxicity?

Answer 7

Area radiated and the dose