Conference Proceeding

Advances in Radiation Oncology: Spot-Scanning Proton Arc (SPArc) Therapy

Dr. Peyman Kabolizadeh ,
Department of Radiation-Oncology, Beaumont Cancer-Institute, Oak

Dr. Peyman Kabolizadeh carried out his Proton Therapy Fellowship, Harvard Medical School, Mass General Hospital, Boston, MA. Later he started working as an Assistant Professor, Radiation Oncologist, Beaumont Health, Royal Oak; MI. has many honors and awards. Presently he is working as Proton Fellowship Program Director.

Purpose: Recent advances in proton therapy planning and delivery have provided the means for complicated treatment planning with higher quality and conformity. Herein, we present a novel robust and delivery-efficient spot-scanning proton arc therapy (SPArc) technique and its impact in different disease sites.
Methods/Materials: SPArc optimization algorithm was developed. Plan quality, robustness and total estimated delivery time were compared. Dose-Volume-Histograms of target and Organs-at-Risk were analyzed taking into account the setup and range uncertainties. Total delivery time was calculated based on a 360-degree gantry room with 1 RPM gantry rotation speed, 2ms-spot switching time, 1nA-beam current, 0.01 minimum spot monitor unit, and energy-layer-switching-time from 0.5 to 4 seconds.
Results: SPArcplan showed potential dosimetric advantages for all clinical scenarios. Compared to Intensity Modulated Proton therapy (IMPT), SPArc delivered less integral dose in all disease sites. Furthermore, evaluating the lung cancer plans, the maximum skin dose, the mean lung dose, and the maximum dose to ribs were reduced by 60%,15% and 35% respectively via SPArc in comparison to IMPT while the conformity index(CI) was improved from 7.6(IMPT) to 4.0(SPArc). All dosimetric advantages were also seen in all other disease sites. In hippocampus sparing whole brain radiotherapy, there was a significant reduction in the mean hippocampus dose by SPArc; 6.20Gy[RBE] compared to VMAT 11.03Gy[RBE] and IMPT 9.28Gy[RBE](p=0.003) along with reduction in cochlear mean dose 6.78Gy[RBE] compared to VMAT 12.45Gy[RBE](p=0.005) and IMPT 10.93Gy[RBE](p=0.028). Moreover, in treating prostate cancer patients, SPArc resulted in significant dose reduction to rectum, bladder, bowel, and femoral heads.
Conclusion: SPArc is the first robust and delivery-efficient proton spot-scanning arc therapy technique, which could potentially be implemented into the future clinical practice.

Published: 11 May 2017