e. When radiation interacts with atoms, energy is deposited resulting in ionization (electron excitation). This ionization may involve certain critical molecules or structures in a cell, producing its characteristic damage. Two modes of action in the cell are direct and indirect action. The radiation may directly hit a particularly sensitive atom or molecule in the cell. The damage from this is irreparable; the cell either dies or is caused to malfunction. The radiation can also damage a cell indirectly by interacting with water molecules in the body. The energy deposited in the water leads to the creation of toxic molecules; the damage is transferred to and affects sensitive molecules through this toxicity.
f. The most radiosensitive organ systems in the body are the male reproductive, the hematopoietic, and the gastrointestinal systems. The relative sensitivity of an organ to direct radiation injury depends upon its component tissue sensitivities. Cellular effects of radiation, whether due to direct or indirect damage, are basically the same for the different kinds and doses of radiation. The simplest effect is cell death. With this effect, the cell is no longer present to reproduce and perform its primary function. Changes in cellular function can occur at lower radiation doses than those that cause cell death. Changes can include delays in phases of the mitotic cycle, disrupted cell growth, permeability changes, and changes in motility. In general, actively dividing cells are most sensitive to radiation. Additionally, radiosensitivity tends to vary inversely with the degree of differentiation of the cell.
g. Predicting radiation effects is difficult because often it is unknown which organs were exposed. Thus, most predictions are based on whole body irradiation. Partial body and specific organ irradiation will occur due to shielding by equipment, from fallout particles, or from internal deposition. Depending upon the organ system, the irradiation can be severe. The severe radiation sickness resulting from external, whole body irradiation and its consequent organ effects is a primary medical concern. The median lethal dose (LD) of radiation that will kill 50 percent of the exposed persons within a period of 60 days (designated as LD50/60) is estimated to be approximately 4.5 gray (Gy) if appropriate medical care is not provided to the casualties. Medical intervention should raise this figure to approximately 10 Gy. This larger figure includes most of the casualties who would be actually capable of reaching medical care following a nuclear detonation, and nearly all those who could be exposed to a RDD. For acute effects of single high dose rate exposures of whole-body irradiation to healthy adults see [Table A-9.]
h. Recovery of a particular cell system will occur if a sufficient fraction of a given stem cell population remains after radiation injury and appropriate stimulation and protection are received. Complete recovery may appear to occur; however, the immune system may repair incompletely with consequent greater susceptibility to future insult from a variety of agents. It is possible for late somatic effects to have a higher probability of occurring because of the radiation damage. Efficacy of both prior and future immunization in this group is not adequately understood.
i. Interactions between radiological injury and chemical or biological agents appear to be synergistic. Insult by these agents in radiologically injured personnel, even in individually subclinical dosages, may result in significant clinical illness.
A-6. Handling and Managing Radiologically Contaminated Patients
a. Radiologically Contaminated Patients. Personnel from contaminated areas may have fallout on their skin and clothing. Although the individual will not be radioactive, he may suffer radiation injury from the contamination. Removal of the contamination should be accomplished as soon as possible; definitely before admission into a clean treatment area. The distinction must be made between a radiation-injured soldier and one who is radiologically contaminated. Although personnel may have received substantial radiation exposure, this exposure alone does not result in the individual being contaminated. Contaminated personnel do not pose a short-term hazard to the medical staff, rather the contamination is a hazard to the individuals' health. However, without patient decontamination, medical personnel may receive sufficient exposure to create beta burns, especially with extended exposure.
b. Handling Radiologically Contaminated Patients. To properly handle radiologically contaminated personnel, medical personnel must first detect the contamination. Detectors that may be used are the AN/PDR27 and AN/VDR2 to monitor patients for contamination. Generally, a reading on the meter twice the current background reading indicates that the patient is contaminated. Monitoring is conducted when potentially contaminated personnel arrive at the MTF. This monitoring is conducted at the MTF's receiving point before admitting the patient. Contaminated patients must be decontaminated before admission. Removal of radiological contamination is less important than immediate lifesaving treatment and providing the best possible medical care. Lifesaving care before decontamination is provided outside the MTF.