[en] With traditional photon therapy to treat large postoperative pancreatic target volume, it often leads to poor tolerance of the therapy delivered and may contribute to interrupted treatment course. This study was performed to evaluate the potential advantage of using passive-scattering (PS) and modulated-scanning (MS) proton therapy (PT) to reduce normal tissue exposure in postoperative pancreatic cancer treatment. A total of 11 patients with postoperative pancreatic cancer who had been previously treated with PS PT in University of Pennsylvania Roberts Proton Therapy Center from 2010 to 2013 were identified. The clinical target volume (CTV) includes the pancreatic tumor bed as well as the adjacent high-risk nodal areas. Internal (iCTV) was generated from 4-dimensional (4D) computed tomography (CT), taking into account target motion from breathing cycle. Three-field and 4-field 3D conformal radiation therapy (3DCRT), 5-field intensity-modulated radiation therapy, 2-arc volumetric-modulated radiation therapy, and 2-field PS and MS PT were created on the patients’ average CT. All the plans delivered 50.4 Gy to the planning target volume (PTV). Overall, 98% of PTV was covered by 95% of the prescription dose and 99% of iCTV received 98% prescription dose. The results show that all the proton plans offer significant lower doses to the left kidney (mean and V_{18 Gy}), stomach (mean and V_{20 Gy}), and cord (maximum dose) compared with all the photon plans, except 3-field 3DCRT in cord maximum dose. In addition, MS PT also provides lower doses to the right kidney (mean and V_{18 Gy}), liver (mean dose), total bowel (V_{20 Gy} and mean dose), and small bowel (V_{15 Gy} absolute volume ratio) compared with all the photon plans and PS PT. The dosimetric advantage of PT points to the possibility of treating tumor bed and comprehensive nodal areas while providing a more tolerable treatment course that could be used for dose escalation and combining with radiosensitizing chemotherapy

[en] To implement a multi-field-optimization (MFO) technique for treating patients with high-Z implants in pencil beam scanning proton-therapy and generate treatment plans that avoids small implants. Two main issues were addressed: (i) the assessment of the optimal CT acquisition and segmentation technique to define the dimension of the implant and (ii) the distance of pencil beams from the implant (avoidance margin) to assure that it does not affect dose distribution. Different CT reconstruction protocols (by O-MAR or standard reconstruction and by 12 bit or 16 bit dynamic range) followed by thresholding segmentation were tested on a phantom with lead spheres of different sizes. The proper avoidance margin was assessed on a dedicated phantoms of different materials (copper/tantalum and lead), shape (square slabs and spheres) and detectors (two-dimensional array chamber and radio-chromic films). The method was then demonstrated on a head-and-neck carcinoma patient, who underwent carotid artery embolization with a platinum coil close to the target. Regardless the application of O-MAR reconstruction, the CT protocol with a full 16 bit dynamic range allowed better estimation of the sphere volumes, with maximal error around −5% in the greater sphere only. Except the configuration with a shallow target (which required a pre-absorber), particularly with a retracted snout, an avoidance margin of around 0.9–1.3 cm allowed to keep the difference between planned and measured dose below 5–10%. The patient plan analysis showed adequate plan quality and confirmed effective implant avoidance. Potential target under-dosage can be produced by patient misalignment, which could be minimized by daily alignment on the implant, identifiable on orthogonal kilovolt images. By implant avoidance MFO it was possible to minimize potential dose perturbation effects produced by small high-Z implants. An advantage of such approach lies in its potential applicability for any type of implant, regardless the precise knowledge of its composition. (note)

[en] To implement a robust multi-field optimization (MFO) technique compatible with the application of a Monte Carlo (MC) algorithm and to evaluate its robustness. Nine patients (three brain, five head-and-neck, one spine) underwent proton treatment generated by a novel robust MFO technique. A hybrid (hMFO) approach was implemented, planning dose coverage on isotropic PTV compensating for setup errors, whereas range calibration uncertainties are incorporated into PTV robust optimization process. hMFO was compared with single-field optimization (SFO) and full robust multi-field optimization (fMFO), both on the nominal plan and the worst-case scenarios assessed by robustness analysis. The SFO and the fMFO plans were normalized to hMFO on CTV to obtain iso-D95 coverage, and then the organs at risk (OARs) doses were compared. On the same OARs, in the normalized nominal plans the potential impact of variable relative biological effectiveness (RBE) was investigated. hMFO reduces the number of scenarios computed for robust optimization (from twenty-one in fMFO to three), making it practicable with the application of a MC algorithm. After normalizing on D95 CTV coverage, nominal hMFO plans were superior compared to SFO in terms of OARs sparing (p   <  0.01), without significant differences compared to fMFO. The improvement in OAR sparing with hMFO with respect to SFO was preserved in worst-case scenarios (p   <  0.01), confirming that hMFO is as robust as SFO to physical uncertainties, with no significant differences when compared to the worst case scenarios obtained by fMFO. The dose increase on OARs due to variable RBE was comparable to the increase due to physical uncertainties (i.e. 4–5 Gy(RBE)), but without significant differences between these techniques. hMFO allows improving plan quality with respect to SFO, with no significant differences with fMFO and without affecting robustness to setup, range and RBE uncertainties, making clinically feasible the application of MC-based robust optimization. (paper)

[en] Highlights: • Clinical implementation of breath-hold treatment technique for liver cancer with PBS. • Interplay effects, setup and range uncertainties impact were assessed for 17 plans. • Inter- and intra-breath hold liver position reproducibility were evaluated. To present our technique for liver cancer treatments with proton therapy in pencil beam scanning mode and to evaluate the impact of uncertainties on plan quality.

[en] This paper aimed to review the literature concerning the use of proton therapy systematically in the treatment of hepatocellular carcinoma, focusing on clinical results and technical issues. The literature search was conducted according to a specific protocol in the Medline and Scopus databases by two independent researchers covering the period of 1990–2012. Both clinical and technical studies referring to a population of patients actually treated with protons were included. The PRISMA guidelines for reporting systematic reviews were followed. A final set of 16 studies from seven proton therapy institutions worldwide were selected from an initial dataset of 324 reports. Seven clinical studies, five reports on technical issues, three studies on treatment related toxicity and one paper reporting both clinical results and toxicity analysis were retrieved. Four studies were not published as full papers. Passive scattering was the most adopted delivery technique. More than 900 patients with heterogeneous stages of disease were treated with various fractionation schedules. Only one prospective full paper was found. Local control was approximately 80% at 3–5 years, average overall survival at 5 years was 32%, with data comparable to surgery in the most favorable groups. Toxicity was low (mainly gastrointestinal). Normal liver V0_G_y < 30%_v_o_l_u_m_e and V30_G_y < 18–25%_v_o_l_u_m_e were suggested as cut-off values for hepatic toxicity. The good clinical results of the selected papers are counterbalanced by a low level of evidence. However, the rationale to enroll patients in prospective studies appears to be strong

[en] A multidisciplinary and multi-institutional working group applied the Failure Mode and Effects Analysis (FMEA) approach to the actively scanned proton beam radiotherapy process implemented at CNAO (Centro Nazionale di Adroterapia Oncologica), aiming at preventing accidental exposures to the patient. FMEA was applied to the treatment planning stage and consisted of three steps: i) identification of the involved sub-processes; ii) identification and ranking of the potential failure modes, together with their causes and effects, using the risk probability number (RPN) scoring system, iii) identification of additional safety measures to be proposed for process quality and safety improvement. RPN upper threshold for little concern of risk was set at 125. Thirty-four sub-processes were identified, twenty-two of them were judged to be potentially prone to one or more failure modes. A total of forty-four failure modes were recognized, 52% of them characterized by an RPN score equal to 80 or higher. The threshold of 125 for RPN was exceeded in five cases only. The most critical sub-process appeared related to the delineation and correction of artefacts in planning CT data. Failures associated to that sub-process were inaccurate delineation of the artefacts and incorrect proton stopping power assignment to body regions. Other significant failure modes consisted of an outdated representation of the patient anatomy, an improper selection of beam direction and of the physical beam model or dose calculation grid. The main effects of these failures were represented by wrong dose distribution (i.e. deviating from the planned one) delivered to the patient. Additional strategies for risk mitigation, easily and immediately applicable, consisted of a systematic information collection about any known implanted prosthesis directly from each patient and enforcing a short interval time between CT scan and treatment start. Moreover, (i) the investigation of dedicated CT image reconstruction algorithms, (ii) further evaluation of treatment plan robustness and (iii) implementation of independent methods for dose calculation (such as Monte Carlo simulations) may represent novel solutions to increase patient safety. FMEA is a useful tool for prospective evaluation of patient safety in proton beam radiotherapy. The application of this method to the treatment planning stage lead to identify strategies for risk mitigation in addition to the safety measures already adopted in clinical practice

[en] Management of patients with head and neck cancers (HNCs) is challenging for the Radiation Oncologist, especially in the COVID-19 era. The Italian Society of Radiotherapy and Clinical Oncology (AIRO) identified the need of practice recommendations on logistic issues, treatment delivery and healthcare personnel’s protection in a time of limited resources. A panel of 15 national experts on HNCs completed a modified Delphi process. A five-point Likert scale was used; the chosen cut-offs for strong agreement and agreement were 75% and 66%, respectively. Items were organized into two sections: (1) general recommendations (10 items) and (2) special recommendations (45 items), detailing a set of procedures to be applied to all specific phases of the Radiation Oncology workflow. The distribution of facilities across the country was as follows: 47% Northern, 33% Central and 20% Southern regions. There was agreement or strong agreement across the majority (93%) of proposed items including treatment strategies, use of personal protection devices, set-up modifications and follow-up re-scheduling. Guaranteeing treatment delivery for HNC patients is well-recognized in Radiation Oncology. Our recommendations provide a flexible tool for management both in the pandemic and post-pandemic phase of the COVID-19 outbreak.