What is the acceptable accuracy for scan and couch position in CT planning?

In CT planning for radiation therapy, an acceptable accuracy for scan and couch position is essential to ensure the precision of treatment delivery. The correct choice of 2 mm reflects the balance between achieving sufficient accuracy to deliver effective treatment while recognizing the practicalities of equipment and patient movement considerations.

A tolerance of 2 mm is typically acceptable because it aligns with the precision required to accurately position the patient and the treatment area within the defined target. This standard helps to minimize geographical miss, which is crucial for effective tumor targeting and sparing of surrounding healthy tissues. Accurate positioning is critical because even small deviations can lead to significant errors in dose delivery, particularly in cases where the tumor is located near critical structures.

Setting the accuracy at 2 mm allows practitioners to account for variations due to patient movement, positioning errors, and the inherent uncertainties in imaging technologies. This level of precision supports enhanced patient safety and treatment effectiveness in radiation therapy.