Monitoring Carbon Ion Beams Transverse Position Detecting Charged Secondary Fragments: Results From Patient Treatment Performed at CNAO

Abstract

Particle therapy in which deep seated tumours are treated using 12C ions (Carbon Ions RadioTherapy or CIRT) exploits the high conformity in the dose release, the high relative biological effectiveness and low oxygen enhancement ratio of such projectiles. The advantages of CIRT are driving a rapid increase in the number of centres that are trying to implement such technique. To fully profit from the ballistic precision achievable in delivering the dose to the target volume an online range verification system would be needed, but currently missing. The 12C ions beams range could only be monitored by looking at the secondary radiation emitted by the primary beam interaction with the patient tissues and no technical solution capable of the needed precision has been adopted in the clinical centres yet. The detection of charged secondary fragments, mainly protons, emitted by the patient is a promising approach, and is currently being explored in clinical trials at CNAO. Charged particles are easy to detect and can be back-tracked to the emission point with high efficiency in an almost background-free environment. These fragments are the product of projectiles fragmentation, and are hence mainly produced along the beam path inside the patient. This experimental signature can be used to monitor the beam position in the plane orthogonal to its flight direction, providing an online feedback to the beam transverse position monitor chambers used in the clinical centres. This information could be used to cross-check, validate and calibrate, whenever needed, the information provided by the ion chambers already implemented in most clinical centres as beam control detectors. In this paper we study the feasibility of such strategy in the clinical routine, analysing the data collected during the clinical trial performed at the CNAO facility on patients treated using 12C ions and monitored using the Dose Profiler (DP) detector developed within the INSIDE project. On the basis of the data collected monitoring three patients, the technique potential and limitations will be discussed.

A hybrid multi-particle approach to range assessment-based treatment verification in particle therapy

“…Finally, although the focus of this manuscript has been on proton therapy scenarios, it is a physics fact that FNs and PGs are also produced abundantly in other PT modalities such as He- and C-ion therapy 22 , 27 , 28 where the same clinical challenges related to range uncertainties are also present. Therefore, it is expected that the use cases of the NOVCoDA can also be extended to range-monitoring applications within these therapy modalities to further reduce treatment toxicities.…”

“…Also, in light of previous results reported in other simulation studies, such as the one by Smeets et al 8 , where range shift detection sensitivities of 1 mm have been achieved down to intensities of 5 × 10 8 protons/spot, it can be stated that the results of this work show that the NOVCoDA could be a feasible approach to range monitoring in PT. Finally, although the focus of this manuscript has been on proton therapy scenarios, it is a physics fact that FNs and PGs are also produced abundantly in other PT modalities such as He-and C-ion therapy 22,27,28 where the same clinical challenges related to range uncertainties are also present. Therefore, it is expected that the use cases of the NOVCoDA can also be extended to range-monitoring applications within these therapy modalities to further reduce treatment toxicities.…”

Hadron Therapy Achievements and Challenges: The CNAO Experience

“…In the case of patients in which morphological changes occurred, the Dose Profiler was able to detect the discrepancy using the χ 2 test. Moreover, the clinical data acquired allowed to study the capability of the Dose Profiler to monitor in vivo the actual transverse position of the beam [50].…”

A hybrid multi-particle approach to range assessment-based treatment verification in particle therapy

“…Finally, although the focus of this manuscript has been on proton therapy scenarios, it is a physics fact that FNs and PGs are also produced abundantly in other PT modalities such as He-and C-ion therapy [22,27,28] where the same clinical challenges related to range uncertainties are also present. Therefore, it is expected that the use cases of the QuDA can also be extended to range-monitoring applications within these therapy modalities to further reduce treatment toxicities.…”