Purpose To preliminary evaluate the role of a re-planning phase and Experience Level (EL) in a multi-institutional study for achieving similar plan quality results and for further benchmarking. Methods Each center was provided with 5 anonymized CTs with pre-delineated volumes and was asked to create SBRT plans according to pre-set dose constraints. Dose prescription to PTV was 7 Gy × 5 fr. Dosimetric parameters, modulation index (MItotal) and dynamic parameters for 45 SBRT IMRT/VMAT plans from 9 centers were analyzed. EL was ranked as 1 for “not-experienced SBRT planner” (never planned prostate SBRT) and 2 for “experienced SBRT planner”. After DVH sharing, planners were asked to re-plan the 5th patient, based on the median DVHs from all participants, for improving target homogeneity and further OAR sparing. Results Each center was provided with 5 anonymized CTs with pre-delineated volumes and was asked to create SBRT plans according to pre-set dose constraints. Dose prescription to PTV was 7Gy × 5fr. Dosimetric parameters, modulation index (MItotal) and dynamic parameters for 45 SBRT IMRT/VMAT plans from 9 centers were analyzed. EL was ranked as 1 for “not-experienced SBRT planner” (never planned prostate SBRT) and 2 for “experienced SBRT planner”. After DVH sharing, planners were asked to re-plan the 5th patient, based on the median DVHs from all participants, for improving target homogeneity and further OAR sparing. Conclusions Both OAR dosimetric parameters and the MItotal correlated with planner’s experience. Plan complexity metrics and dose distributions depended on specific dosimetric planning requests and replanning improved results in terms of homogeneity between centers whilst keeping the same level of plan complexity. This indicates that SBRT planning skills could benefit from a replanning phase after DVH sharing among participant, improving plan quality and homogeneity among centers. These results highlight the importance of training as well as the usefulness of feedback strategies from multi-institutional comparisons. To preliminary evaluate the role of a re-planning phase and Experience Level (EL) in a multi-institutional study for achieving similar plan quality results and for further benchmarking. Each center was provided with 5 anonymized CTs with pre-delineated volumes and was asked to create SBRT plans according to pre-set dose constraints. Dose prescription to PTV was 7 Gy × 5 fr. Dosimetric parameters, modulation index (MItotal) and dynamic parameters for 45 SBRT IMRT/VMAT plans from 9 centers were analyzed. EL was ranked as 1 for “not-experienced SBRT planner” (never planned prostate SBRT) and 2 for “experienced SBRT planner”. After DVH sharing, planners were asked to re-plan the 5th patient, based on the median DVHs from all participants, for improving target homogeneity and further OAR sparing. Each center was provided with 5 anonymized CTs with pre-delineated volumes and was asked to create SBRT plans according to pre-set dose constraints. Dose prescription to PTV was 7Gy × 5fr. Dosimetric parameters, modulation index (MItotal) and dynamic parameters for 45 SBRT IMRT/VMAT plans from 9 centers were analyzed. EL was ranked as 1 for “not-experienced SBRT planner” (never planned prostate SBRT) and 2 for “experienced SBRT planner”. After DVH sharing, planners were asked to re-plan the 5th patient, based on the median DVHs from all participants, for improving target homogeneity and further OAR sparing. Both OAR dosimetric parameters and the MItotal correlated with planner’s experience. Plan complexity metrics and dose distributions depended on specific dosimetric planning requests and replanning improved results in terms of homogeneity between centers whilst keeping the same level of plan complexity. This indicates that SBRT planning skills could benefit from a replanning phase after DVH sharing among participant, improving plan quality and homogeneity among centers. These results highlight the importance of training as well as the usefulness of feedback strategies from multi-institutional comparisons.

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.

Purpose The aim of this work was to compare two approaches of cone-beam computed tomography (CBCT) image intensity-correction for dose recalculation of volumetric arc radiotherapy (VMAT) plans. Methods and materials CBCT-based dose calculation accuracy was assessed for pelvic, lung, and head and neck (H&N) treatment sites. The dose distributions of 10 patients for each body regions were re-calculated by RayStation (RS) and Eclipse treatment planning systems (TPS). In particular CBCT RS were calibrated by patient specific density assignment method supplied by RS TPS, while CBCT ROI , obtained applying ROI-based lookup tables for each body region were used in Eclipse TPS. Dose Volume Histogram (DVH) statistics and 3D γ -analysis (3%, 3 mm) of the dose maps and dose-volume statistics were determined to compare the CBCT dose distributions with those of the planning CTs in absence of morphological changes. Results The results indicate a comparable performance of both intensity correction techniques in the scope of VMAT. The differences in the investigated DVH parameters with respect to the pCT were mostly below 2% for both methods, however the γ -index analysis, being more sensitive to local dose changes, pointed out slight inaccuracies in the CBCT ROI dose distributions with respect to CBCTRS. In particular γ -index pass-rates were found increased for CBCTRS with respect to CBCTROI in pelvic (98% against 95%) in lung (97% against 93%) and in H&N (99% against 95%). Conclusion Both the CBCT intensity correction approaches are attractive options for CBCT dose recalculation and in vivo dose reconstructions [ 1 Fidanzio A. et al. Med Phys. 2014; 41: 062103 Crossref Scopus (19) Google Scholar , 2 Consorti R. et al. Phys Med. 2017; 42: 157-161 Abstract Full Text Full Text PDF PubMed Scopus (12) Google Scholar ]. No added value was found by using a patient-specific HU table, showing similar results as the group based HU tables in terms of DVH indices while the γ -analysis showed better results for CBCTRS. The aim of this work was to compare two approaches of cone-beam computed tomography (CBCT) image intensity-correction for dose recalculation of volumetric arc radiotherapy (VMAT) plans. CBCT-based dose calculation accuracy was assessed for pelvic, lung, and head and neck (H&N) treatment sites. The dose distributions of 10 patients for each body regions were re-calculated by RayStation (RS) and Eclipse treatment planning systems (TPS). In particular CBCT RS were calibrated by patient specific density assignment method supplied by RS TPS, while CBCT ROI , obtained applying ROI-based lookup tables for each body region were used in Eclipse TPS. Dose Volume Histogram (DVH) statistics and 3D γ -analysis (3%, 3 mm) of the dose maps and dose-volume statistics were determined to compare the CBCT dose distributions with those of the planning CTs in absence of morphological changes. The results indicate a comparable performance of both intensity correction techniques in the scope of VMAT. The differences in the investigated DVH parameters with respect to the pCT were mostly below 2% for both methods, however the γ -index analysis, being more sensitive to local dose changes, pointed out slight inaccuracies in the CBCT ROI dose distributions with respect to CBCTRS. In particular γ -index pass-rates were found increased for CBCTRS with respect to CBCTROI in pelvic (98% against 95%) in lung (97% against 93%) and in H&N (99% against 95%). Both the CBCT intensity correction approaches are attractive options for CBCT dose recalculation and in vivo dose reconstructions [ 1 Fidanzio A. et al. Med Phys. 2014; 41: 062103 Crossref Scopus (19) Google Scholar , 2 Consorti R. et al. Phys Med. 2017; 42: 157-161 Abstract Full Text Full Text PDF PubMed Scopus (12) Google Scholar ]. No added value was found by using a patient-specific HU table, showing similar results as the group based HU tables in terms of DVH indices while the γ -analysis showed better results for CBCTRS.

Purpose: EPID-based in vivo dosimetry (IVD) has been implemented for stereotactic body radiotherapy treatments of non-small cell lung cancer to check both isocenter dose and the treatment reproducibility comparing EPID portal images. Methods: 15 patients with lung tumors of small dimensions and treated with volumetric modulated arc therapy were enrolled for this initial experience. IVD tests supplied ratios R between in vivo reconstructed and planned isocenter doses. Moreover a gamma-like analysis between daily EPID portal images and a reference one, in terms of percentage of points with.-value smaller than 1, P.< 1, and mean gamma-values, gamma(mean), using a local 3%-3 mm criteria, was adopted to check the treatment reproducibility. Tolerance levels of 5% for R ratio, P-gamma< 1 higher than 90% and gamma(mean) lower than 0.67 were adopted. Results: A total of 160 EPID images, two images for each therapy session, were acquired during the treatment of the 15 patients. The overall mean of the R ratios was equal to 1.005 +/- 0.014 (1 SD), with 96.9% of tests within +/- 5%. The 2 D image gamma-like analysis showed an overall.mean of 0.39 +/- 0.12 with 96.1% of tests within the tolerance level, and an average P-gamma< 1 value equal to 96.4 +/- 3.6% with 95.4% of tests with P-gamma< 1 > 90%. Paradigmatic discrepancies were observed in three patients: a set-up error and a patient morphological change were identified thanks to CBCT image analysis whereas the third discrepancy was not fully justified. Conclusions: This procedure can provide improved patient safety as well as a first step to integrate IVD and CBCT dose recalculation.

Introduction Small field dosimetry is increasingly important due to the development of complex treatment techniques. Standard dosimetric procedures are mandatory to ensure the same treatment in each radiotherapy center. Purpose A multicentric study on small fields dosimetry for the major linear accelerator manufacturers, using two IBA unshielded silicon diode RAZOR in 30 different institutions in Italy is reported. Data were collected for each linac manufacturer and model with the main objective to provide indications to beginner institutions. Materials and methods In and cross-plane beam profiles and Relative Output ratios were measured for each field size at depth = 10 cm and at SSD = 90 cm. The long axis of the diode detector was placed parallel to the beam with the active volume positioned at the isocenter. The profiles were compared in terms of 80–20% penumbra. Output factors were calculated with respect to a jaw-collimated square field of 3 × 3 cm 2 and as a function of effective field size EOF. Results EOF of all linacs were in agreement within a few per mille from 5.6cm to 1cm FS. For FS below 1cm it is evident a different trend depending on different linac models. Data were fitted with a polynomial showing coefficients of determination R 2 > 0.98 . Penumbra measurements were in agreement each other for each FS and accelerator model. Conclusion Multicentric data have been collected with the same instrumentation and protocol setup, providing good accuracy in the measurements and allowing to create gold standard values to be used by those institutions who intend to implement new performing treatment techniques.

_____________________________________________________________________________________________________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.

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/Objective: The aim of this study was to find out early cardiac changes from doxorubicin based chemotherapy and radiotherapy in patients with early and locally advanced carcinoma breast and to assess cardiac changes in relation to radiation dose received by heart.Materials and Methods: Investigations like ECG, ECHO and ERV (Equilibrium radionuclide ventriculography) were done at baseline, after chemotherapy, after radiotherapy and after 6 months of followup.Changes in ECG, ECHO and ERV were recorded at different time periods during the study.Left ventricular ejection fraction (LVEF) was recorded using both ECHO and ERV.In ECHO other parameters like Fractional shortening (FS), Mitralvalve E point septal separation (MVEPSS) and PEP/LVET ratio (Pre ejectionperiod/Left ventricular ejection time) were recorded.Patients were divided into 4 groups according to the sequence of chemotherapy and radiotherapy.Results: The most common ECG change was T wave inversion in the pre-cordial leads.One patient had ST depression in V4 & V5 leads and 2 patients had physiological T wave inversion in Lead III.In Group 1 mean LVEF (ECHO) at baseline was 66.79 ±3.73.It decreased to 63.45 ± 3.54 after chemotherapy.It further decreased to 61.64 ± 4.26 after RT.On follow up there was a further decline to 61.42 ±3.27.In Group 2 baseline mean LVEF was 66.67 ± 4.33.Post RT it slightlydecreased to 66 ± 4.975, while post chemotherapyit further declined to 62.7 ± 2.92.During follow up mean LVEF further decreased to 61.89 ± 2.934.In Group 4 baseline mean LVEF was 67.25 ± 4.33, which decreased after chemotherapy to 64.75 ± 2.062.During follow up it further decreased to 63.25 ± 2.363.LVEF was also measured by MUGA/ ERV.In Group 1 mean LVEF at baseline was 58.14 ±2.997.After chemotherapy it decreased to 56.15 ± 3.144.After RT it increased to 56.21 ± 3.81 and during follow up mean LVEF decreased to 55.21 ± 2.913.In Group 2 mean LVEF at baseline was 59.11 ± 1.41.Post RT decreased to 58.67 ±2.872 and post chemotherapy it decreased to 54.44 ± 1.81.During follow up it increased to 55.22 ± 1.787.In Group 4 mean LVEF at baseline was 60 ± 1.63, which decreased to 58.75 ± 1.89 after chemotherapy.During follow up it further decreased to 56.25 ± 2.63.Conclusions: Our prospective study shows that a significant number of patients can develop a transient depression in ventricular function after chemotherapy and radiotherapy.ECG changes in our study were not specific.T wave inversion was the most common abnormality, suggestive of ventricular repolarisation abnormality.Decrease in LVEF was seen in our patients both by conventional ECHO and MUGA/ ERV scan during different phases of treatment.These changes indicate that doxorubicin based chemotherapy and radiotherapy produces acute abnormality in left ventricular function.Whether these results are predictive of the development of chronic cardiac toxicity can only be answered by serially investigating these patients for a longer duration.

A chemical vapour deposition diamond detector fabricated at Rome ‘Tor Vergata’ University was investigated for its applicability as transfer dosimeter in radiotherapy photon beams with small field sizes. The detector consists of a single crystal diamond with a very small sensitive volume (0.004 mm3). The detector showed a measurement repeatability of 0.1% and a long term reproducibility of 0.4%. Monte Carlo simulations revealed a response dependence on the photon beam energy of about 2% from the 60Co quality to 10 MV photon beam. The calculated detector response was found to be independent of field size within 0.5% from 10 cm × 10 cm to 2 cm × 2 cm beam size for both 6 MV and 10 MV photon beams, increasing in smaller field sizes. Dw values obtained by the diamond detector were found to be in agreement with Dw values obtained by a small volume ionization chamber in photon beams with field size down to 2 cm × 2 cm.