The effect of radiation on normal tissue varies widely between individuals. Consequently, a test to measure tissue response to radiation could be clinically useful by permitting more accurate titration of dosage in patients undergoing radiotherapy. Also, in view of emerging concerns about possible nuclear terrorism a test for exposure to radiation might also be useful in evaluating victims of a "dirty bomb" explosion. A number of different techniques have been previously reported in epidemiological studies for the estimation of prior radiation exposure. This study explores one approach to estimating radiation exposure by measurement of increased oxidative stress which can be detected by a breath test.

In this study subjects undergoing significant exposure to therapeutic radiation will provide breath samples for analysis in a central laboratory. The hypothesis of the study is that the analysis of these samples will lead to the identification of a set of markers of radiation exposure.

Inclusion Criteria:

1. Age 18 years or older
2. Subject is willing and able to cooperate with study and give signed informed consent to participate
3. Subject has been diagnosed with a condition that requires treatment with a TBI protocol of daily irradiation for one to five days
4. Actively smoking subjects, as well as never smokers and former smokers are eligible for the study so long as a complete smoking consumption history can be recorded
5. Subject will be available for follow-up breath tests following each session of TBI. Subjects receiving only one day of TBI will be available for a follow-up 24-36 hours following TBI
6. Subject is an in-patient at the hospital

Exclusion Criteria:

1. Subject has had chemotherapy within preceding 21 days

Subjects undergoing total body irradiation prior to chemotherapy.