Author(s)

Aileen B. Chen¹, Yulia Lyatskaya¹, Joseph H. Killoran¹, Michelle Boyd¹, Shrooti Singh¹, Scott Kaplin², Aaron M. Allen²

¹Department of Radiation Oncology, Dana-Farber Cancer Institute/Brigham and Women’s Hospital, Boston, MA, USA.
²Department of Radiation Oncology, Davidoff Center, Petach Tikvah, Israel.

Objective: The standard practice in fractionated radiation of using of visual alignment of tattoos with weekly portal imaging for radiation setup can miss setup errors. We previously reported on the feasibility of using an automated infrared-guided positioning system (iGPS) for daily radiation setup. In this study, we prospectively evaluate whether use of iGPS can improve daily setup errors for patients with thoracic malignancies. Methods: Multiple external infrared markers were placed on patients undergoing thoracic radiation at the time of simulation. Patients were immobilized using vacuum immobilization bag and wing-board. Patients were aligned for treatment using only the iGPS system. Daily portal images were then taken, and shifts in patient position were recorded. Differences between isocenter position using iGPS versus daily portal imaging were calculated. Results: Data were collected for 698 treatment sessions for 27 patients. We found that in 94.0%, 96.4%, and 93.7% of treatment sessions, isocenter position differed between iGPS and daily portal imaging by ≤5 mm in the left/right(L/R), anterior/posterior(A/P), and superior/inferior(S/I) directions, respectively. Isocenter position differed by 5 - 10 mm in 5.7% (L/R), 3.6% (A/P), and 5.9% (S/I) of treatment sessions, and by >10 mm in 0.3% (L/R), 0.0% (A/P), and 0.4% (S/I) of treatment sessions. Three-dimensional shifts were also calculated, with differences in isocenter position as follows: 94.9% ≤5 mm, 5.1% 5 - 10 mm, and 0.2% >10 mm. This compares favorably to our prior studies. Discussion: Daily treatment setup using an infrared-guided patient positioning system, correlates well with daily portal imaging and may help to improve daily treatment setup for patients with thoracic malignancies.

Radiotherapy, Infrared Markers, Thoracic Malignancies

Chen, A. , Lyatskaya, Y. , Killoran, J. , Boyd, M. , Singh, S. , Kaplin, S. and Allen, A. (2017) Prospective Study of Infrared-Guided Patient Setup for Fractionated Thoracic Radiation. International Journal of Medical Physics, Clinical Engineering and Radiation Oncology, 6, 313-322. doi: 10.4236/ijmpcero.2017.63028.