Ultra-fast prompt gamma detection in single proton counting regime for range monitoring in particle therapy.

In order to fully exploit the ballistic potential of particle therapy, we propose an online range monitoring concept based on time-of-flight (TOF)-resolved prompt gamma (PG) detection in a single proton counting regime. In a proof of principle experiment, different types of monolithic scintillating gamma detectors are read in time coincidence with a diamond-based beam hodoscope, in order to build TOF spectra of PG generated in a target presenting an air cavity of variable thickness. Since the measurement was carried out at low beam currents (< 1 proton/bunch) it was possible to reach excellent coincidence time resolutions, of the order of 100 ps (σ). Our goal is to detect possible deviations of the proton range with respect to treatment planning within a few intense irradiation spots at the beginning of the session and then carry on the treatment at standard beam currents. The measurements were limited to 10 mm proton range shift. A Monte Carlo simulation study reproducing the experiment has shown that a 3 mm shift can be detected at 2σ by a single detector of ∼1.4 × 10-3 absolute detection efficiency within a single irradiation spot (∼108 protons) and an optimised experimental set-up.

[Chondrosarcoma of the soft parts of the thoracic wall. Apropos of a case after surgery and irradiation of breast adenocarcinoma]. / Chondrosarcome des parties molles de la paroi thoracique. A propos d'un cas après adénocarcinome mammaire opéré et irradié.

We are reporting here a case of chondrosarcoma of the soft tissues of the thoracic wall. As far as we can tell it is the first case published in the world. The tumour appeared 13 years after radical mastectomy and radiotherapy for an adenocarcinoma of the breast. The tumor was greyish-white in appearance and hard, but friable and haemorrhagic. Clinically and biologically it looked like an inflammatory mass. This disappeared when the tumour had been removed but recurred 6 days post-operatively when nodules showing that it had permeated the tissues appeared. Histological and immunohistochemical examination confirmed the diagnosis. We discuss the clinical and histological aspects of the case and state what we found in the literature about other sarcomas that have followed adenocarcinomata of the breast that had been irradiated and operated on. The role of radiotherapy in bringing about this tumour is discussed, including the relationship between the site of the tumour and the dose and field of irradiation. The prognosis is particularly bad in this type of sarcoma which was induced by irradiation.