Room: AAPM ePoster Library
Purpose: Traditional radiation treatments require tattoos for daily positioning. These permanent markings can be a cause for patient dissatisfaction and distress. The use of surface guidance (SG) can eliminate the need for tattoos, however the accuracy of a tattooless patient setup warrants validation. In this study, patients requiring treatment of various anatomical sites were positioned using two methods--SG and standard tattoo based (TB) setup. The accuracy of the systems was compared.
Method: Twenty patients with a total of 400 fractions from various anatomical sites (5 head/neck, 5 chest, 5 abdomen/pelvis and 5 breast cancers) were randomly selected. Each patient was positioned with alternating methods for each fraction. The time that the patient lies on the table to initiation of the CBCT, was recorded. The setup shifts for each method were also recorded.
Results: Among these patients, we found the setup time was shorter for TB than SG for head/neck (18.6± 6.5 VS 37.7± 26.4 Seconds) and abdomen/pelvis (73.3±15.0 VS 81.5±11.8 Seconds). The TB was longer for the chest (87.6± 22.1 VS 77.8± 12.3 Seconds) and breast (84.9± 1.9 VS 74.5± 2.5 Seconds.)
The overall average 6 degrees shift differences between TB and SG for various sites are as follows: The Long, Lat, Vert, Rot, Pitch, and roll shift differences for HN are (0.2, 0.1, 0.6 mm and 0.01, 0.04, 0.04 degrees ); for chest are (0.2, 0.4, 0.0 mm and 0.05, 0.1, 0.05 degrees); For abdomen/pelvis are (0.9, 0.6, 0.1mm and 0.03, 0.02, 0.09 degrees); for breast are (0.9, 0.4, 1.0mm and 0.0, 0.0, 0.0 degrees); respectively.
Conclusions: The setup accuracy and the setup time were comparable for both tattoo and surface imaging based setups. Hence, SG based setup may provide an alternative for patients who wish to avoid permanent tattoos.