Purpose Stereotactic body radiation therapy (SBRT) approach for treating early stage solid tumor and metastases is increasing worldwide. In 2013 the Italian Association of Medical Physicists (AIFM) constituted a working group in order to standardize SBRT dosimetric aspects. A survey was designed aiming to delineate the status of the technology applied in SBRT on a national level. Clinical evaluation of SBRT was out of the present study. Methods A questionnaire was designed by three medical physicists expert of SBRT using Google Forms containing questions regarding image-guidance solutions, respiratory management, delivery mode, treatment planning system (TPS) commissioning, and QA approach. A large number of medical physicists from 54 centers with heterogeneous technology was invited to participate and 45 of them completed the survey. Experts were asked to provide suggestions based on personal experience and specificity. Results After two webcall and two versions, the final questionnaire was developed. Results showed great heterogeneity in terms of technologies, image-guidance solutions, respiratory management, delivery mode, TPS commissioning and QA approach. The most available delivery system was conventional linacs with VMAT modality; the most common energies used were 6 MV and 6 MV-FFF; for the 56% of centers robotic couch was available, CBCT was the most used IGRT technique (78% of centers) and 40% of centers did not use respiratory management during treatment delivery. The smallest measured field size for lateral beam profiles was lower than 1 × 1 cm2, while only the 62% of centers used the same field size for the TPS commissioning (from 1 × 1 cm2 to 4 × 4 cm2). A large number of centers (51%) feel the necessity to upgrade their dosimetric devices dedicated to SBRT QA. Conclusions This survey on SBRT could allow to improve the QA procedure and to define minimum requirements for SBRT dosimetric verification. Stereotactic body radiation therapy (SBRT) approach for treating early stage solid tumor and metastases is increasing worldwide. In 2013 the Italian Association of Medical Physicists (AIFM) constituted a working group in order to standardize SBRT dosimetric aspects. A survey was designed aiming to delineate the status of the technology applied in SBRT on a national level. Clinical evaluation of SBRT was out of the present study. A questionnaire was designed by three medical physicists expert of SBRT using Google Forms containing questions regarding image-guidance solutions, respiratory management, delivery mode, treatment planning system (TPS) commissioning, and QA approach. A large number of medical physicists from 54 centers with heterogeneous technology was invited to participate and 45 of them completed the survey. Experts were asked to provide suggestions based on personal experience and specificity. After two webcall and two versions, the final questionnaire was developed. Results showed great heterogeneity in terms of technologies, image-guidance solutions, respiratory management, delivery mode, TPS commissioning and QA approach. The most available delivery system was conventional linacs with VMAT modality; the most common energies used were 6 MV and 6 MV-FFF; for the 56% of centers robotic couch was available, CBCT was the most used IGRT technique (78% of centers) and 40% of centers did not use respiratory management during treatment delivery. The smallest measured field size for lateral beam profiles was lower than 1 × 1 cm2, while only the 62% of centers used the same field size for the TPS commissioning (from 1 × 1 cm2 to 4 × 4 cm2). A large number of centers (51%) feel the necessity to upgrade their dosimetric devices dedicated to SBRT QA. This survey on SBRT could allow to improve the QA procedure and to define minimum requirements for SBRT dosimetric verification.

Purpose Currently, most of the multicenter analyses on treatment planning rely on the extraction of selected data from the DVH of each plan. A grouped analysis can be biased due to different algorithms implemented in different TPSs used to generate the DVH. In this work we used a consistent method to present a preliminary analysis of multiple data coming from a national survey on stereotactic body radiotherapy (SBRT) planning. Methods A single spine case was shared among 36 radiation oncology centers. The dose prescription was 30 Gy in 3 fractions with specific constraints on target coverage and dose to nearby organs at risk. Data were collected in DICOM-RT format. A script was developed in R language using the RadOnc R-Package for recalculating the DVHs using the same algorithm. Specific DVH points (V30Gy, D90%, D2%) collected from the centers were compared with those recalculated with RadOnc. A grouped analysis of recalculated DVHs was performed therefore eliminating the bias due to different DVH calculation algorithms. Results Differences between collected and recalculated DVHs were minimal, however in some cases deviations up to 1.5% were observed. The multiple-DVH analysis showed a notable variability on target dose level (Fig. 1), up to 150% likely related to constraints on target coverage and SBRT technique. This variability was caused mainly by different planning optimization strategies, rather than by the use of a specific treatment technology. Conclusions The observed variability suggests that comparable standards in patient treatment among different centers can be obtained if a consistent high-level data sharing capability is granted. In the strive to harmonize the planning process, this analysis constitutes a first step toward the creation of a platform of crowd-knowledge-based planning guidelines. This platform could represent a high-quality benchmark for those centers that are willing to implement SBRT techniques (concept expressed in Fig. 1). Currently, most of the multicenter analyses on treatment planning rely on the extraction of selected data from the DVH of each plan. A grouped analysis can be biased due to different algorithms implemented in different TPSs used to generate the DVH. In this work we used a consistent method to present a preliminary analysis of multiple data coming from a national survey on stereotactic body radiotherapy (SBRT) planning. A single spine case was shared among 36 radiation oncology centers. The dose prescription was 30 Gy in 3 fractions with specific constraints on target coverage and dose to nearby organs at risk. Data were collected in DICOM-RT format. A script was developed in R language using the RadOnc R-Package for recalculating the DVHs using the same algorithm. Specific DVH points (V30Gy, D90%, D2%) collected from the centers were compared with those recalculated with RadOnc. A grouped analysis of recalculated DVHs was performed therefore eliminating the bias due to different DVH calculation algorithms. Differences between collected and recalculated DVHs were minimal, however in some cases deviations up to 1.5% were observed. The multiple-DVH analysis showed a notable variability on target dose level (Fig. 1), up to 150% likely related to constraints on target coverage and SBRT technique. This variability was caused mainly by different planning optimization strategies, rather than by the use of a specific treatment technology. The observed variability suggests that comparable standards in patient treatment among different centers can be obtained if a consistent high-level data sharing capability is granted. In the strive to harmonize the planning process, this analysis constitutes a first step toward the creation of a platform of crowd-knowledge-based planning guidelines. This platform could represent a high-quality benchmark for those centers that are willing to implement SBRT techniques (concept expressed in Fig. 1).

Purpose Stereotactic Body Radiation Therapy (SBRT) for patients with early stage solid tumor is increasing thanks to modern technologies and integrated image-guided systems. A national study to evaluate the influence of calculation grid resolution and CT slice thickness on small fields calculated in an homogeneous phantom, is in progress. For this purpose, a preliminary investigation that collected different parameters on TPS management at Italian level, was performed. Methods Twenty-eight centres of the Italian Association of Medical Physics (AIFM) SBRT working group were invited to fill out a questionnaire expressly prepared by expert Medical Physicists using Google Forms. Questions regarded: type of accelerator, MLC characteristics, CT images scan information, Treatment Planning System (TPS) type, strategy used for SBRT plans, small fields OF values, detector/detectors and set-up adopted for measurements. Results Preliminary results from 28 centers show great heterogeneities. Most centers used LINACs with MLC width ⩽5 mm, 6MV and VMAT technique. 60% of centers used more than one detector to measure OFs and no corrective factor was adopted in small field data. 10 × 10 cm2 field size was the normalization field. OF data inserted in TPS did not come from a multicenter OF measurements. 1 × 1 cm2 was the smallest field size measured for 47% of centers. As for TPS, PB, CCC, MC, AAA and deteministic algorithms were used in 3%, 40%, 23%, 27% and 7% of centers, respectively. About 29% and 21 % of centers used 3 mm and 2 mm as CT slice thickness, respectively. 50% of centers used 2 mm calculation grid. Conclusions The influence of the dose calculation resolution and CT slice thickness on small OFs has not been studied yet. This preliminary study, considered as the starting point, highlighted a great spread of answers of the participating center and could be used as a baseline for future investigations.

_____________________________________________________________________________________________________printed boluses.Gafchromic EBT3 film (International Specialty Products, Wayne, NJ) placed between phantom slabs provided dose profile measurements.An Epson Expression Scanner 10000 XL (Epson, Long Beach, CA) was used to determine the optical density of the films and film analysis were performed using Film QA Pro software (Ashland Inc., Bridgewater, NJ). Results:The mean value of Hounsfield unit (HU) of the 3D printed boluses was provided analyzing their Computed Tomography (CT) scans.Negative HU were due to the air gap inside the infill pattern.The mean HU increased with the percentage infill, resulting in higher bolus density (Tab.1).This reduced the distance from the surface of the phantom where the maximum dose occurs (dmax) as shown in Fig. 1.Build-up peaks shifted towards the phantom surface when any bolus was used.ABS and PLA boluses with an infill percentage of 40% had comparable performance to the commercial bolus. Conclusion:The dosimetric analysis of the 3D printed flat boluses showed that they can decrease the skin-sparing as a commercially available bolus.The performed analysis accurately describes the physical behavior of these plastic materials, in order to represent them in treatment planning system for precise treatment delivery.Moreover, patientspecific boluses could be outlined from patient CT images and 3D printed, thus shaping the actual anatomy of the patient.This procedure may represent a viable alternative to commercially available conventional boluses, potentially improving the fitting between bolus and skin surfaces.

Introduction: The Italian Association of Medical Physics (AIFM) created a working group to assess planning homogeneity between different technologies and among different Italian centers to compare and evaluate SBRT plans for prostate cancer. The purpose was to compare inter-institutional variations in clinically acceptable dose distributions with variation in the treatment planning and delivery apparatus, to assess dosimetric consistency among different hospitals.

A project dedicated to stereotactic body radiotherapy (SBRT) dosimetric aspects started in the framework of the Italian Association of Medical Physics (AIFM) SBRT working group. Its main objectives are manifold but sharing the knowledge between different clinics is the one of the most important. More than 30 centres, equipped with Varian, Elekta, Siemens or CyberKnife linac were enrolled. The project was divided in several work-packages, the first one evaluated the relative measurements with detectors routinely used by individual centers and in the following different detectors run in various centre. Each centre in the same work-package performed dose profile of field size ranging from 0.6 × 0.6 cm2 to 5.0 × 5.0 cm2, and relative output factors (ROF) measurements with a diamond or silicon diode or scintillator detector. In workpackage-1 ROF values measured in the first phase were compared with the ones measured with a microdiamond showing a higher inter-center consistency with this dosimeter compared to routine detectors. In workpackage-2 a silicon diode of new generation was used also to develop a mathematical relation from multicentric experimental data, which describes and predicts the ROF as a function of effective field size for TrueBeam Varian and Elekta linacs. Workpackage-3 used a plastic scintillator for TPR20, 10 and ROF; the latter showed a greater variability. Workpackage-4 used diamond and plastic scintillator with Cyberknife beams, to evaluate if microDiamond could be a suitable alternative to silicon diodes for OF determination and to validate the feasibility of using the scintillator as a reference detector in consideration of the ČerenkovLightRatio and experimental uncertainties. The results of the study for all the detectors emphasized the usefulness of a multi-center validation over a single center approach. A project dedicated to stereotactic body radiotherapy (SBRT) dosimetric aspects started in the framework of the Italian Association of Medical Physics (AIFM) SBRT working group. Its main objectives are manifold but sharing the knowledge between different clinics is the one of the most important. More than 30 centres, equipped with Varian, Elekta, Siemens or CyberKnife linac were enrolled. The project was divided in several work-packages, the first one evaluated the relative measurements with detectors routinely used by individual centers and in the following different detectors run in various centre. Each centre in the same work-package performed dose profile of field size ranging from 0.6 × 0.6 cm2 to 5.0 × 5.0 cm2, and relative output factors (ROF) measurements with a diamond or silicon diode or scintillator detector. In workpackage-1 ROF values measured in the first phase were compared with the ones measured with a microdiamond showing a higher inter-center consistency with this dosimeter compared to routine detectors. In workpackage-2 a silicon diode of new generation was used also to develop a mathematical relation from multicentric experimental data, which describes and predicts the ROF as a function of effective field size for TrueBeam Varian and Elekta linacs. Workpackage-3 used a plastic scintillator for TPR20, 10 and ROF; the latter showed a greater variability. Workpackage-4 used diamond and plastic scintillator with Cyberknife beams, to evaluate if microDiamond could be a suitable alternative to silicon diodes for OF determination and to validate the feasibility of using the scintillator as a reference detector in consideration of the ČerenkovLightRatio and experimental uncertainties. The results of the study for all the detectors emphasized the usefulness of a multi-center validation over a single center approach.

Introduction: The AIFM working group on MR intercomparison has proposed a quality assurance protocol for magnetic resonance spectroscopy (MRS). The aim of this study is to test the protocol on a significant number of clinical MR scanners.

Conclusions: This new tool would enable the risk-benefit judgements in addition to the rest of the TPS conventional parameters, for the optimal treatment choice.The big error bars shown in the pelvic cases, are due to the fact of considering the mean values of neutron doses obtained for a huge variety of treatments and techniques.They decrease when considering a more homogeneous inter-centres pathology, as the rectum.Treatments that combine low and high energies use a lower number of high energy MU and thus neutron doses are smaller.This fact should be considered in the script for future studies.A good concordance has been observed with previous studies [2] for these cases.Future works should be carried out to analyse other pathologies for a higher number of patients.

Conclusions:Results exhibited a good synchronization between 4D-PET and the system used to register the respiratory wave, accurate enough to use it for clinical purpose.For the 4 types of movement, the cranio-caudal displacement between the syringe from the 4D-PET and ANZAI were less than 2.30 mm.Moreover, mean difference showed that in most of the cases, curves were out of phase.This might lead to a systematic error in the tumour position.It could be interesting to run more measurements for different cycles and 4D-PET acquisitions if we want to modify the margins for the GTV due to the use of 4D-PET for tumor contouring.

Purpose: To explore a novel patient-dose DVH-based method for pretreatment dose quality assurance tests. Methods: 20 IMRT plans for head-and-neck cancer patients were used. A comparison was performed between the planned dose distributions, the computed, and the reconstructed ones using the gamma-index (GI) method. The GI analysis was performed using both the 3%/3 mm and the 2%/2 mm criteria. Results: No significant DVH-deviation was observed. Considering the 3%/3 mm criteria the mean GI% < 1 for the body and structures was significantly higher compared to 2%/2 mm criteria. Conclusions: Our results underline the importance of QA-methods based on DVH-metrics to predict the impact of delivered dose.