P. Fossati

Proton beam radiotherapy: report of the first ten patients treated at the "Centro Nazionale di Adroterapia Oncologica (CNAO)" for skull base and spine tumours.

PurposeThe Italian National Centre for Oncological Hadrontherapy (Centro Nazionale di Adroterapia Oncologica, CNAO), equipped with a proton and ion synchrotron, started clinical activity in September 2011. The clinical and technical characteristics of the first ten proton beam radiotherapy treatments are reported.Materials and methodsTen patients, six males and four females (age range 27–73xa0years, median 55.5), were treated with proton beam radiotherapy. After one to two surgical procedures, seven patients received a histological diagnosis of chordoma (of the skull base in three cases, the cervical spine in one case and the sacrum in three cases) and three of low-grade chondrosarcoma (skull base). Prescribed doses were 74xa0GyE for chordoma and 70xa0GyE for chondrosarcoma at 2xa0GyE/fraction delivered 5xa0days per week.ResultsTreatment was well tolerated without toxicity-related interruptions. The maximal acute toxicity was grade 2, with oropharyngeal mucositis, nausea and vomiting for the skull base tumours, and grade 2 dermatitis for the sacral tumours. After 6–12xa0months of follow-up, no patient developed tumour progression.ConclusionsThe analysis of the first ten patients treated with proton therapy at CNAO showed that this treatment was feasible and safe. Currently, patient accrual into these as well as other approved protocols is continuing, and a longer follow-up period is needed to assess tumour control and late toxicity.

Surgical spacer placement prior carbon ion radiotherapy (CIRT): an effective feasible strategy to improve the treatment for sacral chordoma

BackgroundSacral chordoma (SC) is a neoplasm arising from residual notochordal cells degeneration. SC is difficult to manage mainly because of anatomic location and tendency to extensive spread. Carbon ion radiotherapy (CIRT) is highly precise to selectively deliver high biological effective dose to the tumor target sparing the anatomical structure on its path even if when SC is contiguous to the intestine, and a surgical spacer might be an advantageous tool to create a distance around the target volume allowing radical curative dose delivery with a safe dose gradient to the surrounding organs. This paper describes a double approach—open and hand-assisted laparoscopic—for a silicon spacer placement in patients affected by sacral chordoma undergoing carbon ion radiotherapy.MethodsSix consecutive patients have been enrolled for surgical spacer placement—open (three) or hand-assisted (three)—prior carbon ion radiotherapy treatment in order to increase efficacy of carbon ion radiotherapy minimizing its side effects.ResultsResults showed that silicon spacer placement for SC treatment is feasible both via laparoscopic and laparotomic approach.ConclusionsIts use might improve CIRT safety and thus efficacy for SC treatment.

Salivary Gland. Photon beam and particle radiotherapy: Present and future.

Salivary gland cancers (SGCs) are rare diseases and their treatment depends upon histology, stage and site of origin. Radical surgery is the mainstay of treatment but radiotherapy (RT) plays a key role in both the postoperative and the inoperable setting, as well as in recurrent disease. In the absence of prospective randomized trials, a wide retrospective literature suggests postoperative RT (PORT) in patients with high risk pathological features. SGCs, and adenoid cystic carcinoma (ACC) in particular, are known to be radio-resistant tumors and should therefore respond well to particle beam therapy. Recently, excellent outcome has been reported with radical carbon ion RT (CIRT) in particular for ACC. Both modern photon- and hadron-based treatments are effective and are characterized by a favourable toxicity profile. But it is not clear whether one modality is superior to the other for disease control, due to the differences in patients selection, techniques, fractionation schedules and outcome measurements among clinical experiences. In this paper, we review the role of photon and particle RT for malignant SGCs, discussing the difference between modalities in terms of biological and technical characteristics. RT dose and target volumes for different histologies (ACC versus non-ACC) have also been taken into consideration.

Proton beam radiotherapy: report of the first patient treated at the Centro Nazionale di Adroterapia Oncologica (CNAO) [National Center of Oncologic Hadron Therapy].

Proton beam radiotherapy, an innovative treatment modality, allows delivery of high radiation doses to the target while sparing surrounding healthy structures. The Centro Nazionale di Adroterapia Oncologica (CNAO), equipped with a synchrotron and capable of using both protons and ions, initiated its clinical activity in September 2011. The first treatment of a skull base tumor with protons is reported here. The case of a 26-year-old man with an intracranial low-grade chondrosarcoma of the right petroclival junction is discussed with emphasis on technical and clinical details. Two previous surgical interventions had achieved partial removal of the tumor and the patient was treated with protons for residual disease. The prescribed dose was 70 GyE in 35 fractions of 2 GyE. Treatment was completed with minimal acute toxicity consisting of grade 1 alopecia and nausea. Nine months after treatment the disease is locally controlled. Use of high-energy protons at CNAO is a safe and effective means of treating a tumor located near critical normal structures.

Risk of carotid blowout after reirradiation with particle therapy

Purpose Carotid blowout (CB) is a serious complication in retreatment of neoplasms in the head and neck (H&N) region. Rates seem to increase in hypofractionated or accelerated hyperfractionated regimens. In this study, we investigate the CB rate and the cumulative doses received by the carotid artery (CA) in a cohort of patients who were reirradiated at CNAO with particle therapy in the H&N region. Methods and materials The dosimetric information, medical records, and tumor characteristics of 96 patients were analyzed. For 49 of these patients, the quality of dosimetric information was sufficient to calculate the cumulative doses to the CA. The corresponding biological equivalent dose in 2 Gy fractions (EQD2) was calculated with an α/β-ratio of 3. Results In the final reirradiation at CNAO, 17 patients (18%) had been treated with protons and 79 (82%) with carbon ions. Two patients experienced profuse oronasal bleeding, of which one case was confirmed to be caused by CB. If attributing both cases to CB, we found an actuarial CB rate of 2.7%. Interestingly, there were no CB cases in the carbon ion group even though this was the large majority of patients and they generally were treated more aggressively in terms of larger fraction doses and higher cumulative EQD2. Conclusions The current practice of particle reirradiation at CNAO for recurrent neoplasms in the H&N region results in acceptable rates of CB.

EP-1759: Treatment of moving targets with active scanning carbon ion beams

performance testing and development of a micro-calorimeter based on Superconducting QUantum Interference Devices (SQUIDs) (1). Unlike other microdosimetric detectors that are used for investigating the energy distribution, this detector provides a direct measurement of energy deposition at the micrometer scale, that can be used to improve our understanding of biological effects in particle therapy application, radiation protection and environmental dosimetry. Temperature rises of less than 1μK are detectible and when combined with the low specific heat capacity of the absorber at cryogenic temperature, extremely high energy deposition sensitivity of approximately 0.4 eV can be achieved (2). The detector consists of 3 layers: a tissue equivalent (TE) absorber, a superconducting absorber and a silicon substrate. Ideally all energy would be absorbed in the TE absorber and heat rise in the superconducting layer would arise due to heat conduction from the TE layer. However, in practice direct particle absorption occurs in all 3 layers and must be corrected for. To investigate the thermal behavior within the detector, and quantify any possible correction, particle tracks were simulated employing Geant4 (v9.6) Monte Carlo simulations. The track information was then passed to the COMSOL Multiphysics (Finite Element Method) software. The 3D heat transfer within each layer was then evaluated in a timedependent model. For a statistically reliable outcome, the simulations had to be repeated for a large number of particles. An automated system has been developed that couples Geant4 Monte Carlo output to COMSOL for determining the expected distribution of proton tracks and their thermal contribution within the detector. Preliminary results of a 3.8 MeV proton beam showed that the detector reaches the equilibrium state after 8 ns. It is estimated that 20% of the temperature rise in the superconducting absorber is due to heat conduction from the adjacent absorber which needs to be corrected for. The simulations were repeated for proton beams with energies of 2, 10, 62 and 230 MeV.

Dosimetric characterization of carbon fiber stabilization devices for post-operative particle therapy

PURPOSEnThe aim of this study was to evaluate the dosimetric impact caused by recently introduced carbon fiber reinforced polyetheretherketone (CF/PEEK) stabilization devices, in comparison with conventional titanium (Ti) implants, for post-operative particle therapy (PT).nnnMETHODSnAs a first step, protons and carbon ions Spread-Out Bragg Peaks (SOBPs) were delivered to CF/PEEK and Ti screws. Transversal dose profiles were acquired with EBT3 films to evaluate beam perturbation. Effects on image quality and reconstruction artifacts were then investigated. CT scans of CF/PEEK and Ti implants were acquired according to our clinical protocol and Hounsfield Unit (HU) mean values were evaluated in three regions of interest. Implants and artifacts were then contoured in the sample CT scans, together with a target volume to simulate a spine tumor. Dose calculation accuracy was assessed by comparing optimized dose distributions with Monte Carlo simulations. In the end, the treatment plans of nine real patients (seven with CF/PEEK and two with Ti stabilization devices) were retrospectively analyzed to evaluate the dosimetric impact potentially occurring if improper management of the spine implant was carried out.nnnRESULTSnAs expected, CF/PEEK screw caused a very slight beam perturbation in comparison with Ti ones, leading to a lower degree of dose degradation in case of contouring and/or set-up uncertainties. Furthermore, CF/PEEK devices did not determine appreciable HU artifacts on CT images thus improving image quality and, as a final result, dose calculation accuracy.nnnCONCLUSIONSnCF/PEEK spinal fixation devices resulted dosimetrically more suitable than commonly-used Ti implants for post-operative PT.

OC-0250: Hadrontherapy as re-irradiation using active beam delivery at CNAO

Material and Methods: Between September 2013 and September 2015, data on 138 children (78 males, 60 females, aged 0.9-17.9 years (median 5.7 years)) were prospectively collected in KiProReg at WPE. Diagnoses were CNS tumours (n=73), sarcomas (n=59), extracranial germ cell tumors (n=3) and others (n=3), respectively. Treatment sites were brain (n=72), head and neck including base of skull (n=38), spine (n=15), or pelvis (n=13). In 73.9% of the patients, macroscopic residual disease was present before PT. The median total dose of PT was 54.0 Gy (range 29.8-74.0 Gy). Only two patients had a mixed beam technique. Due to the very young age, sedation was necessary in 55.1% of children. Concurrent chemotherapy was applied in 54.3% of children. Side-effects were classified according to Common Terminology Criteria for Adverse Events (CTCAE) V4.0 grading system.