We developed a checklist to help navigate the radiation simulation and setup process. We distilled the tasks to be performed into an easily memorizable acronym P-P-I-I-I-T (Patient Prescription, Patient Position, Immobilization, Imaging, Image Guided Radiotherapy, and Treatment Technique). This checklist ensures coverage of all the key elements and improves patient safety and treatment planning quality. Since our initial publication, we applied the checklist on 600 patients and are now presenting an update. We updated the checklist to ensure inclusion of the American College of Radiology (ACR) recommendations for radiation planning and incorporated feedback we received from allied radiation oncology professionals. The inspiration behind the easily memorizable acronym, P-P-I-I-I-T, came from a similar published checklist for systematically evaluating of a radiotherapy treatment plan, CB-CHOP, which stands for Contours, Beam Arrangement, Coverage, Heterogeneity/Hot Spots, Organs at Risk and Prescription (Dean et al. 2017), The checklist provides a simplified and standardized approach to treatment plan evaluation. Similarly, P-P-I-I-I-T checklist was put into usage as aid for both learners and staff radiation oncologists, and applied to radiation planning for 600 patients treated in Iowa between 2019 to 2022. During each session another radiation oncologist, two dosimetrists, two radiation nurses, and one physicist were present. The other radiation oncologist acted as observer to ensure the checklist was being applied appropriately by the primary radiation oncologist. The rest of the treatment team provided feedback which was relevant to their professional domains. The feedback from all members was collected and incorporated to make revisions to an updated checklist which was put into use as of January 2023. The components of the revised list are as follows: The following are the components of the revised 2023 checklist: P - Patient Prescription: Confirms the proposed dose, fractionation, and scheduling (such as concurrent chemotherapy). P - Patient Position: Describes optimal position including head, shoulder, arms and legs, alternative positions, and changes due to unexpected issues. I - Immobilization: Considers type of device, 4D set-up, gating, and custom immobilization. I - Imaging: Chooses imaging modality, slice thickness, and contrast agent, as well as fusions for SBRT and SRS. Discusses image guidance incorporating ACR recommendations and reference points. T - Treatment Technique: Includes proposed technique such as 3D, VMAT, electrons, and bolus and energy to be used. Standardization of practical guidelines and safety checklists are increasingly common in medicine. P-P-I-I-I-T (P²I³T) continues to be a simple acronym that can be used by radiation oncology residents and attendings as a checklist to ensure a complete and accurate patient setup and simulation.