Integration of a real‐time tumor monitoring system into gated proton spot‐scanning beam therapy: An initial phantom study using patient tumor trajectory data

Abstract

The results suggested that by properly adjusting irradiation control parameters, gated proton spot-scanning beam therapy can be robust to target motion. This is an important first step toward establishing treatment plans in real patient geometry.

Preliminary analysis for integration of spot-scanning proton beam therapy and real-time imaging and gating

“…We showed +/-2mm windows are considered to be appropriate enough in suppressing dose error, and our previous report also showed the +/-2mm gating window is ideal in the point of view of dose uniformity and delivery time [5]. But further investigation is required for revealing the criteria to set individual gating windows.…”

“…In the present study, we investigated the relationship between the organ motion and SSPT. The details of the analysis of the internal motion of fiducial markers can be more useful in the evaluation of interplay effects in SSPT [5]. Another problem with the gating method is the possibility of its prolonging the treatment time.…”

“…A gated proton beam was irradiated to a clinical target volume (CTV) of 5 ×5×5 cm 3 in a water phantom, in synchronization with the tumor trajectory log of the Hokkaido data. The gating window was set to ±2 mm based on previous simulation study [5]. The plan was constructed to deliver a 2 Gy dose to the internal target volume (ITV), which was defined as CTV + 5 mm.…”

Optimization and evaluation of multiple gating beam delivery in a synchrotron-based proton beam scanning system using a real-time imaging technique

“…In order to improve the gated irradiation efficiency with synchrotron based proton therapy, variable flat top phase synchrotron operation, described in the later section, has been applied. However, the gating signals change irregularly and sporadically under complex tumor motions [18] and, in some cases, poor recognition of the fiducial markers [19,20]. The resulting fluctuations in the gating signal can significantly reduce the gated irradiation efficiency in variable flat top phase synchrotron operation [21].…”

“…The resulting fluctuations in the gating signal can significantly reduce the gated irradiation efficiency in variable flat top phase synchrotron operation [21]. To improve the gated irradiation efficiency, we have developed a real-time-image gated proton beam therapy (RGPT) system [22][23][24] which has a new function, called the multiple gated-irradiation function [20,25]. The combination of variable flat top phase operation and multiple gated-irradiation function was realized in the first in RGPT.…”