Final answer:
When radiographing children, the exposure should be made within seconds of positioning to prevent motion blur and ensure clear images. Exposure times such as 0.250 seconds are tailored to pediatric patients to minimize radiation exposure while achieving diagnostic-quality images. Calculations must consider area size, absorption rates in tissue, and exposure time.
Step-by-step explanation:
When radiographing infants and children, the goal should be to make the exposure as quickly as possible, ideally within seconds from the time the child is positioned. Quick exposures are crucial to prevent motion blur due to movement, which is common with pediatric patients. The faster the exposure, the more likely the imaging will be clear and of diagnostic quality, reducing the need for repeat exposures.
In medical imaging, especially with pediatrics, factors such as the size of the area being imaged (0.0750 m²), the percentage of x-rays absorbed in tissue (35.0% of the x-rays are absorbed in 20.0 kg of tissue), and the exposure time (0.250 s) are critical components for calculating the correct exposure settings needed to get a clear image, while minimizing the radiation dose to the patient. Therefore, adjustments are always made to accommodate the fast metabolism and higher sensitivity to radiation in children compared to adults.
It is also important to note that in therapy contexts, like with a cancer patient receiving y rays, the dose calculation is different and much more precise, taking into account factors like concentration of rays that reach the patient and the specific absorption rate in the affected tissue, which includes the dose in rem and the energy per decay.