<qa>  What is the name of the surgical procedure that patients may have undergone?13. More than four weeks must have elapsed since any prior systemic therapy at the time the patient receives the preparative regimen, and patients toxicities must have recovered to a grade 1 or less except for toxicities such as alopecia or vitiligo. Note: Patients may have undergone minor surgical procedures within the past 3 weeks, as long as all toxicities have recovered to grade 1 or less 