What type of exposure is least likely to occur in a radiation therapy department?

In a radiation therapy department, internal exposure is least likely to occur because the procedures and treatments primarily involve external beam radiation aimed at the tumor site, targeting specific areas of the body.

External exposure refers to radiation emanating from a source outside the body, which is common in therapeutic settings where patients receive radiation treatments from linear accelerators or cobalt units. Direct exposure is also likely in such environments, as radiation is intentionally directed towards patient tumors, and staff are trained to manage exposure during treatment.

Radiation leaks, while they are a concern and must be monitored closely, are typically managed through rigorous safety protocols and equipment maintenance, making them infrequent events. In contrast, internal exposure, which occurs when radioactive substances enter the body, is generally not a standard procedure in radiation therapy departments since treatments focus on addressing cancer through external means, rather than using internal radiation sources like brachytherapy or radiopharmaceuticals. Therefore, internal exposure is indeed the least likely scenario in this context.