Chapter 13
Radiation cataractogenesis



1. Which of the following statements is false?

a. By "cataract" is denoted any detectable change in the normally transparent lens of the eye.

b. Cataracts can be caused by irradiation of the lens.

c. Cell division in the lens continues throughout life.

d. The lens has the same mechanisms for cell removal as other normal tissues.



2. Which of the following statements is true?

a. Even low doses (2.5-6.5 Gy) induce, in most cases, severe opacity of the lens.

b. High doses to the lens (6.5-11.5 Gy) can result in lost of vision.

c. The probability of cataract induction by radiation is a function of the dose only and does not depend on the exposure time.

d. Increasing the dose does not affect the probability for the occurence of a progressive cataract.



3. In the case of radiotherapy patients, it has been shown that the lens can tolerate a higher dose with increased fractionation and overall treatment time.

a. True.

b. False.



4. The average latent period for cataract in the lens for patients that have received 2.5 to 6.5 Gy is:

a. 1 year.

b. 5 years.

c. 8 years.

d. 20 years.



5. The average latent period for cataract in the lens for patients that have received 6.5 to 11.5 Gy is:

a. 1 year.

b. 4 years.

c. 10 years.

d. 17 years.



6. Which of the following statements is false?

a. The dose-response relationship for radiation-induced cataract has been reconstructed with high accuracy.

b. There seems to be a threshold for the induction of detectable lens opacification by radiation.

c. Animal experiments indicate that high LET radiations have a high RBE for lens opacification.

d. Radiation-induced cataracts are a deterministic late effect (there is a threshold below which they do not occur and the severity of the biologic response is dose-related).