Radiomic- and dosiomic-based clustering development for radio-induced neurotoxicity in pediatric medulloblastoma.

BACKGROUND: Texture analysis extracts many quantitative image features, offering a valuable, cost-effective, and non-invasive approach for individual medicine. Furthermore, multimodal machine learning could have a large impact for precision medicine, as texture biomarkers can underlie tissue microstructure. This study aims to investigate imaging-based biomarkers of radio-induced neurotoxicity in pediatric patients with metastatic medulloblastoma, using radiomic and dosiomic analysis. METHODS: This single-center study retrospectively enrolled children diagnosed with metastatic medulloblastoma (MB) and treated with hyperfractionated craniospinal irradiation (CSI). Histological confirmation of medulloblastoma and baseline follow-up magnetic resonance imaging (MRI) were mandatory. Treatment involved helical tomotherapy (HT) delivering a dose of 39 Gray (Gy) to brain and spinal axis and a posterior fossa boost up to 60 Gy. Clinical outcomes, such as local and distant brain control and neurotoxicity, were recorded. Radiomic and dosiomic features were extracted from tumor regions on T1, T2, FLAIR (fluid-attenuated inversion recovery) MRI-maps, and radiotherapy dose distribution. Different machine learning feature selection and reduction approaches were performed for supervised and unsupervised clustering. RESULTS: Forty-eight metastatic medulloblastoma patients (29 males and 19 females) with a mean age of 12 ± 6 years were enrolled. For each patient, 332 features were extracted. Greater level of abstraction of input data by combining selection of most performing features and dimensionality reduction returns the best performance. The resulting one-component radiomic signature yielded an accuracy of 0.73 with sensitivity, specificity, and precision of 0.83, 0.64, and 0.68, respectively. CONCLUSIONS: Machine learning radiomic-dosiomic approach effectively stratified pediatric medulloblastoma patients who experienced radio-induced neurotoxicity. Strategy needs further validation in external dataset for its potential clinical use in ab initio management paradigms of medulloblastoma.

European Society for Radiotherapy and Oncology Advisory Committee in Radiation Oncology Practice consensus recommendations on patient selection and dose and fractionation for external beam radiotherapy in early breast cancer.

High-quality randomised clinical trials testing moderately fractionated breast radiotherapy have clearly shown that local control and survival is at least as effective as with 2 Gy daily fractions with similar or reduced normal tissue toxicity. Fewer treatment visits are welcomed by patients and their families, and reduced fractions produce substantial savings for health-care systems. Implementation of hypofractionation, however, has moved at a slow pace. The oncology community have now reached an inflection point created by new evidence from the FAST-Forward five-fraction randomised trial and catalysed by the need for the global radiation oncology community to unite during the COVID-19 pandemic and rapidly rethink hypofractionation implementation. The aim of this paper is to support equity of access for all patients to receive evidence-based breast external beam radiotherapy and to facilitate the translation of new evidence into routine daily practice. The results from this European Society for Radiotherapy and Oncology Advisory Committee in Radiation Oncology Practice consensus state that moderately hypofractionated radiotherapy can be offered to any patient for whole breast, chest wall (with or without reconstruction), and nodal volumes. Ultrafractionation (five fractions) can also be offered for non-nodal breast or chest wall (without reconstruction) radiotherapy either as standard of care or within a randomised trial or prospective cohort. The consensus is timely; not only is it a pragmatic framework for radiation oncologists, but it provides a measured proposal for the path forward to influence policy makers and empower patients to ensure equity of access to evidence-based radiotherapy.

Accelerated hypofractionated radiation for elderly or frail patients with a newly diagnosed glioblastoma: A pooled analysis of patient-level data from 4 prospective trials.

BACKGROUND: The standard of care for elderly or frail patients with glioblastoma (GBM) is 40 Gy in 15 fractions of radiotherapy. However, this regimen has a lower biological effective dose (BED) compared with the Stupp regimen of 60 Gy in 30 fractions. It is hypothesized that accelerated hypofractionated radiation of 52.5 Gy in 15 fractions (BED equivalent to Stupp) is safe and efficacious. METHODS: Elderly or frail patients with GBM treated with 52.5 Gy in 15 fractions were pooled from 3 phase 1/2 studies and a prospective observational study. Overall survival (OS) and progression-free survival (PFS) were defined time elapsing between surgery/biopsy and death from any cause or progression of disease. RESULTS: Sixty-two newly diagnosed patients were eligible for this pooled analysis of individual patient data. The majority (66%) had a Karnofsky performance status (KPS) score <70. The median age was 73 years. The median OS and PFS were 10.3 and 6.9 months, respectively. Patients with KPS scores ≥70 and <70 had a median OS of 15.3 and 9.5 months, respectively. Concurrent chemotherapy was an independent prognostic factor for improved PFS and OS. Grade 3 neurologic toxicity was seen in 2 patients (3.2%). There was no grade 4/5 toxicity. CONCLUSIONS: This is the only analysis of elderly/frail patients with GBM prospectively treated with a hypofractionated radiation regimen that is isoeffective to the Stupp regimen. Treatment was well tolerated and demonstrated excellent OS and PFS compared with historical studies. This regimen gives the elderly/frail population an alternative to regimens with a lower BED. Randomized trials are needed to validate these results.

Clinical validation of an automatic atlas-based segmentation tool for male pelvis CT images.

PURPOSE: This retrospective work aims to evaluate the possible impact on intra- and inter-observer variability, contouring time, and contour accuracy of introducing a pelvis computed tomography (CT) auto-segmentation tool in radiotherapy planning workflow. METHODS: Tests were carried out on five structures (bladder, rectum, pelvic lymph-nodes, and femoral heads) of six previously treated subjects, enrolling five radiation oncologists (ROs) to manually re-contour and edit auto-contours generated with a male pelvis CT atlas created with the commercial software MIM MAESTRO. The ROs first delineated manual contours (M). Then they modified the auto-contours, producing automatic-modified (AM) contours. The procedure was repeated to evaluate intra-observer variability, producing M1, M2, AM1, and AM2 contour sets (each comprising 5 structures × 6 test patients × 5 ROs = 150 contours), for a total of 600 contours. Potential time savings was evaluated by comparing contouring and editing times. Structure contours were compared to a reference standard by means of Dice similarity coefficient (DSC) and mean distance to agreement (MDA), to assess intra- and inter-observer variability. To exclude any automation bias, ROs evaluated both M and AM sets as "clinically acceptable" or "to be corrected" in a blind test. RESULTS: Comparing AM to M sets, a significant reduction of both inter-observer variability (p < 0.001) and contouring time (-45% whole pelvis, p < 0.001) was obtained. Intra-observer variability reduction was significant only for bladder and femoral heads (p < 0.001). The statistical test showed no significant bias. CONCLUSION: Our atlas-based workflow proved to be effective for clinical practice as it can improve contour reproducibility and generate time savings. Based on these findings, institutions are encouraged to implement their auto-segmentation method.

Validation of a secondary dose check tool against Monte Carlo and analytical clinical dose calculation algorithms in VMAT.

PURPOSE: Patient-specific quality assurance (QA) is very important in radiotherapy, especially for patients with highly conformed treatment plans like VMAT plans. Traditional QA protocols for these plans are time-consuming reducing considerably the time available for patient treatments. In this work, a new MC-based secondary dose check software (SciMoCa) is evaluated and benchmarked against well-established TPS (Monaco and Pinnacle3 ) by means of treatment plans and dose measurements. METHODS: Fifty VMAT plans have been computed using same calculation parameters with SciMoCa and the two primary TPSs. Plans were validated with measurements performed with a 3D diode detector (ArcCHECK) by translating patient plans to phantom geometry. Calculation accuracy was assessed by measuring point dose differences and gamma passing rates (GPR) from a 3D gamma analysis with 3%-2 mm criteria. Comparison between SciMoCa and primary TPS calculations was made using the same estimators and using both patient and phantom geometry plans. RESULTS: TPS and SciMoCa calculations were found to be in very good agreement with validation measurements with average point dose differences of 0.7 ± 1.7% and -0.2 ± 1.6% for SciMoCa and two TPSs, respectively. Comparison between SciMoCa calculations and the two primary TPS plans did not show any statistically significant difference with average point dose differences compatible with zero within error for both patient and phantom geometry plans and GPR (98.0 ± 3.0% and 99.0 ± 3.0% respectively) well in excess of the typical 95 % clinical tolerance threshold. CONCLUSION: This work presents results obtained with a significantly larger sample than other similar analyses and, to the authors' knowledge, compares SciMoCa with a MC-based TPS for the first time. Results show that a MC-based secondary patient-specific QA is a clinically viable, reliable, and promising technique, that potentially allows significant time saving that can be used for patient treatment and a per-plan basis QA that effectively complements traditional commissioning and calibration protocols.

Automated planning through robust templates and multicriterial optimization for lung VMAT SBRT of lung lesions.

PURPOSE: To develop and validate a robust template for VMAT SBRT of lung lesions, using the multicriterial optimization (MCO) of a commercial treatment planning system. METHODS: The template was established and refined on 10 lung SBRT patients planned for 55 Gy/5 fr. To improve gradient and conformity a ring structure around the planning target volume (PTV) was set in the list of objectives. Ideal fluence optimization was conducted giving priority to organs at risk (OARs) and using the MCO, which further pushes OARs doses. Segmentation was conducted giving priority to PTV coverage. Two different templates were produced with different degrees of modulation, by setting the Fluence Smoothing parameter to Medium (MFS) and High (HFS). Each template was applied on 20 further patients. Automatic and manual plans were compared in terms of dosimetric parameters, delivery time, and complexity. Statistical significance of differences was evaluated using paired two-sided Wilcoxon signed-rank test. RESULTS: No statistically significant differences in PTV coverage and maximum dose were observed, while an improvement was observed in gradient and conformity. A general improvement in dose to OARs was seen, which resulted to be significant for chest wall V30 Gy , total lung V20 Gy , and spinal cord D0.1 cc . MFS plans are characterized by a higher modulation and longer delivery time than manual plans. HFS plans have a modulation and a delivery time comparable to manual plans, but still present an advantage in terms of gradient. CONCLUSION: The automation of the planning process for lung SBRT using robust templates and MCO was demonstrated to be feasible and more efficient.

Methodological approach to create an atlas using a commercial auto-contouring software.

PURPOSE: The aim of this work was to establish a methodological approach for creation and optimization of an atlas for auto-contouring, using the commercial software MIM MAESTRO (MIM Software Inc. Cleveland OH). METHODS: A computed tomography (CT) male pelvis atlas was created and optimized to evaluate how different tools and options impact on the accuracy of automatic segmentation. Pelvic lymph nodes (PLN), rectum, bladder, and femurs of 55 subjects were reviewed for consistency by a senior consultant radiation oncologist with 15 yr of experience. Several atlas and workflow options were tuned to optimize the accuracy of auto-contours. The deformable image registration (DIR), the finalization method, the k number of atlas best matching subjects, and several post-processing options were studied. To test our atlas performances, automatic and reference manual contours of 20 test subjects were statistically compared based on dice similarity coefficient (DSC) and mean distance to agreement (MDA) indices. The effect of field of view (FOV) reduction on auto-contouring time was also investigated. RESULTS: With the optimized atlas and workflow, DSC and MDA median values of bladder, rectum, PLN, and femurs were 0.91 and 1.6 mm, 0.85 and 1.6 mm, 0.85 and 1.8 mm, and 0.96 and 0.5 mm, respectively. Auto-contouring time was more than halved by strictly cropping the FOV of the subject to be contoured to the pelvic region. CONCLUSION: A statistically significant improvement of auto-contours accuracy was obtained using our atlas and optimized workflow instead of the MIM Software pelvic atlas.

A multiparametric method to assess the MIM deformable image registration algorithm.

A quantitative evaluation of the performances of the deformable image registration (DIR) algorithm implemented in MIM-Maestro was performed using multiple similarity indices. Two phantoms, capable of mimicking different anatomical bending and tumor shrinking were built and computed tomography (CT) studies were acquired after applying different deformations. Three different contrast levels between internal structures were artificially created modifying the original CT values of one dataset. DIR algorithm was applied between datasets with increasing deformations and different contrast levels and manually refined with the Reg Refine tool. DIR algorithm ability in reproducing positions, volumes, and shapes of deformed structures was evaluated using similarity indices such as: landmark distances, Dice coefficients, Hausdorff distances, and maximum diameter differences between segmented structures. Similarity indices values worsen with increasing bending and volume difference between reference and target image sets. Registrations between images with low contrast (40 HU) obtain scores lower than those between images with high contrast (970 HU). The use of Reg Refine tool leads generally to an improvement of similarity parameters values, but the advantage is generally less evident for images with low contrast or when structures with large volume differences are involved. The dependence of DIR algorithm on image deformation extent and different contrast levels is well characterized through the combined use of multiple similarity indices.

Real-time beam monitoring for error detection in IMRT plans and impact on dose-volume histograms : A multi-center study.

PURPOSE: This study aimed to test the sensitivity of a transmission detector for online dose monitoring of intensity-modulated radiation therapy (IMRT) for detecting small delivery errors. Furthermore, the correlation of changes in detector output induced by small delivery errors with other metrics commonly employed to quantify the deviations between calculated and delivered dose distributions was investigated. METHODS: Transmission detector measurements were performed at three institutions. Seven types of errors were induced in nine clinical step-and-shoot (S&S) IMRT plans by modifying the number of monitor units (MU) and introducing small deviations in leaf positions. Signal reproducibility was investigated for short- and long-term stability. Calculated dose distributions were compared in terms of γ passing rates and dose-volume histogram (DVH) metrics (e.g., Dmean, Dx%, Vx%). The correlation between detector signal variations, γ passing rates, and DVH parameters was investigated. RESULTS: Both short- and long-term reproducibility was within 1%. Dose variations down to 1 MU (∆signal 1.1 ± 0.4%) as well as changes in field size and positions down to 1 mm (∆signal 2.6 ± 1.0%) were detected, thus indicating high error-detection sensitivity. A moderate correlation of detector signal was observed with γ passing rates (R2 = 0.57-0.70), while a good correlation was observed with DVH metrics (R2 = 0.75-0.98). CONCLUSION: The detector is capable of detecting small delivery errors in MU and leaf positions, and is thus a highly sensitive dose monitoring device for S&S IMRT for clinical practice. The results of this study indicate a good correlation of detector signal with DVH metrics; therefore, clinical action levels can be defined based on the presented data.

Hypofractionated radiotherapy with simultaneous integrated boost (SIB) plus temozolomide in good prognosis patients with glioblastoma: a multicenter phase II study by the Brain Study Group of the Italian Association of Radiation Oncology (AIRO).

INTRODUCTION: A multicenter phase II study for assessing the efficacy and the toxicity of hypofractionated radiotherapy with SIB plus temozolomide in patients with glioblastoma was carried out by the Brain Study Group of the Italian Association of Radiation Oncology. METHODS: Twenty-four patients with newly diagnosed glioblastoma belonging to Recursive Partitioning Analysis classes III and IV were enrolled. The prescribed dose was 52.5 Gy in 15 fractions of 3.5 Gy and 67.5 in 15 fractions of 4.5 Gy to the SIB volume. Dose constraints for the hypofractionated schedule were provided. Radiotherapy was associated with concomitant and sequential temozolomide. RESULTS: Median overall survival (OS) was 15.1 months, while median progression-free survival (PFS) was 8.6 months. Actuarial OS at 12 months was 65.6% ± 0.09, whereas actuarial PFS at 12 months was 41.2% ± 0.10. Status of methylation of MGMT promoter resulted to be a significant prognostic factor for OS. Radiotherapy-related acute toxicity was not relevant. Three patients (12.5%) had G3 myelotoxicity that required temozolomide temporary interruption or dose reduction during the chemotherapy. However, chemotherapy was not definitely discontinued for toxicity in any case. One patient out of 24 (4.2%) developed radionecrosis that required surgical resection with no evidence of disease in the surgical specimen. CONCLUSIONS: This trial confirms that hypofractionated radiotherapy with SIB and association with temozolomide may be a reasonable and feasible option for good prognosis patients with GBM.

A dosimetric comparison between CyberKnife and tomotherapy treatment plans for single brain metastasis.

PURPOSE: Radiosurgery (RS) is a well-established treatment in selected patients with brain metastasis. The aim of this study is to compare the differences between CyberKnife (CK) and TomoTherapy (HT) treatment plans of RS of single brain metastasis (BM) to define when HT should be used in cases beyond Cyberknife-when both systems are readily available for the radiation oncologist. METHODS AND MATERIALS: Nineteen patients with single brain metastasis treated with CK were re-planned for radiosurgery using TomoTherapy Hi-ART system. Two planning approaches have been used for TomoTherapy plans: the classical one (HT) and the improved conformity (icHT) that produces dose distributions more similar to those of RS plans. PTV coverage, Conformity Index (CI), Paddick Conformity Index (nCI), Homogeneity Index (HI), Gradient Index (GI), and beam on time of CK, HT, and icHT plans were evaluated and compared. RESULTS: A good coverage was found for CK, HT, and icHT plans. A difference between mean HI of CK and icHT plans was observed (p = 0.007). Better dose gradients compared to both icHT and HT modalities were observed in CK plans. icHT modality showed improved mean CI respect to HT modality, similar to that obtained in CK plans. CONCLUSIONS: CK plans show higher conformity and lower GI than icHT and HT plans. TomoTherapy demonstrates the advantage of being a device capable to reach different clinical objectives depending on the different planning modality employed. CyberKnife and TomoTherapy are both optimal RS devices, the choice to use one over another has to be clinically guided.

Accelerated partial breast irradiation using intensity-modulated radiotherapy technique compared to whole breast irradiation for patients aged 70 years or older: subgroup analysis from a randomized phase 3 trial.

The purpose of this study was to report the efficacy and the safety profile on the subset of selected early breast cancer (BC) patients aged 70 years or older from a single-center phase 3 trial comparing whole breast irradiation (WBI) to accelerated partial breast irradiation (APBI) using intensity-modulated radiation therapy technique. Between 2005 and 2013, 520 patients aged more than 40 years old were enrolled and randomly assigned to receive either WBI or APBI in a 1:1 ratio. Eligible patients were women with early BC (maximum diameter 2.5 cm) suitable for breast conserving surgery. This study is registered with ClinicalTrials.gov, NCT02104895. A total of 117 patients aged 70 years or more were analyzed (58 in the WBI arm, 59 in the APBI arm). At a median follow-up of 5-years (range 3.4-7.0), the ipsilateral breast tumor recurrence (IBTR) rate was 1.9 % in both groups. No significant difference between the two groups was identified (log-rank test p = 0.96). The 5-year disease-free survival (DFS) rates in the WBI group and APBI group were 6.1 and 1.9 %, respectively (p = 0.33). The APBI group presented significantly better results in terms of acute skin toxicity, considering both any grade (p = 0.0001) and grade 2 or higher (p = 0.0001). Our subgroup analyses showed a very low rate and no significant difference in terms of IBTR, using both WBI and APBI. A significant impact on patients compliance in terms of acute and early late toxicity was shown, which could translate in a consistent improvement of overall quality of life.

Surface imaging, portal imaging, and skin marker set-up vs. CBCT for radiotherapy of the thorax and pelvis.

AIM: The aim of this study was to compare surface imaging, portal imaging, and skin marker set-up in radiotherapy of thoracic and pelvic regions, using cone beam computed tomography (CBCT) data as the gold standard. PATIENTS AND METHODS: Twenty patients were included in this study. CBCT, surface acquisition (SA), and two orthogonal portal images (PI) were acquired during the first four treatment sessions. Patient set-up corrections, obtained by registering the planning CT with CBCT, were used as the gold standard. Registration results of the PI and SA were evaluated and compared with those obtained with CBCT. The advantage derived from using SA or PI verification systems over a skin marker set-up was also quantified. RESULTS: A statistically significant difference between PI and SA (in favour of PI) was observed in seven patients undergoing treatment of the pelvic region and in two patients undergoing treatment of the thoracic region. The use of SA or PI, compared with a skin marker set-up, improved patient positioning in 50% and 57% of the thoracic fractions, respectively. For pelvic fractions, the use of PI was beneficial in 73% of the cases, while the use of SA was beneficial in only 45%. Patient positioning worsened with SA, particularly along longitudinal and vertical directions. CONCLUSION: PI yielded more accurate registration results than SA for both pelvic and thoracic fractions. Compared with the skin marker set-up, PI performances were superior to SA for pelvic fractions while comparable results were obtained for thoracic fractions.

Four-dimensional computed tomography in accelerated partial breast irradiation planning: single series from a phase III trial.

PURPOSE: The aim of our study was to evaluate the usefulness of the four-dimensional computed tomography (4DCT) in accelerated partial breast irradiation (aPBI) planning. MATERIALS AND METHODS: At our Institute, we have been treating the index quadrant with external intensity-modulated radiation therapy in a phase III trial. For this study, we selected a sample of 10 patients with right- or left-sided breast cancer and surgical clips at the excision site. Contouring of the target was performed both using three-dimensional computed tomography (3DCT) and 4DCT imaging. On both 3DCT and 4DCT, we recorded the clinical target volume (CTV) and the planning target volume (PTV) and the coordinates of the PTV centroid. We calculated the treatment plans, according to our protocol, using the contours drawn on the 3DCT and 4DCT and evaluated target coverage and sparing of organs at risk (OAR). RESULTS: Median age of the patients was 63.5 years (range 52-75). The comparison between the 3DCT and 4DCT PTV volumes was not statistically significant (p = 0.79). Concerning centroid coordinates, the average absolute differences were 0.1 mm in the latero-lateral, 0.7 mm in the antero-posterior and 0.3 mm in the supero-inferior direction. No statistically significant differences were observed both in PTV coverage and OAR sparing; the 4D PTV contour is adequately covered when the plan based on the 3D contours is used. Target coverage was reduced on average by 1 % and no statistically significant difference was observed (p = 0.93). CONCLUSIONS: In our experience, no significant differences between PTV volumes, PTV coverage, OAR sparing and centroid position are evidenced when comparing 3DCT and 4DCT plans. Conventional 3DCT-based planning is adequate for aPBI.

Comparison of stereotactic plans for brain tumors with two different multileaf collimating systems.

Linac-based stereotactic radiosurgery (SRS) has been widely used for treating small intracranial lesions. This technique allows conforming the dose distribution to the planning target volume (PTV), providing a steep dose gradient with the surrounding normal tissues. This is realized through dedicated collimation systems. The present study aims to compare SRS plans with two collimating systems: the beam modulator (BM) of the Elekta Synergy linac and the DirexGroup micromultileaf collimator (µMLC). Seventeen patients (25 PTVs) were planned both with BM and µMLC (mounted on an Elekta Precise linac) using the Odyssey (PerMedics) treatment planning system (TPS). Plans were compared in terms of dose-volume histograms (DVH), minimum dose to the PTV, conformity index (CI), and homogeneity index (HI), as defined by the TPS, and doses to relevant organs at risk (OAR). The mean difference between the µMLC and the BM plans in minimum PTV dose was 5.7% ± 4.2% in favor of the µMLC plans. No statistically significant difference was found between the distributions of the CI values for the two planning modalities (p = 0.54), while the difference between the distributions of the HI values was statistically significant (p = 0.018). For both BM and µMLC plans, no differences were observed in CI and HI, depending on lesion size and shape. The PTV homogeneity achieved by BM plans was 15.1% ± 6.8% compared to 10.4% ± 6.6% with µMLC. Higher maximum and mean doses to OAR were observed in the BM plans; however, for both plans, dose constraints were respected. The comparison between the two collimating systems showed no substantial differences in terms of PTV coverage or OAR sparing. The improvements obtained by using µMLC are relatively small, and both systems turned out to be adequate for SRS treatments.

Impact of a breathing-control system on target margins and normal-tissue sparing in the treatment of lung cancer: experience at the radiotherapy unit of Florence University.

PURPOSE: In lung cancer, a high radiation dose to the target area correlates with better local control but is frequently counterbalanced by a higher risk of lung toxicity. Several methods exist to coordinate respiratory motion in lung radiotherapy. We aimed to investigate the impact of a breathing-control system on irradiated volumes and dosimetric parameters in three-dimensional conformal radiotherapy (3D-CRT) and stereotactic radiotherapy (SRT) treatments. MATERIALS AND METHODS: Twelve patients were scheduled for radical radiotherapy: five for SRT and seven for 3D-CRT. For each patient, in addition to the free-breathing computed tomography (CT) scan, four additional sets of CT slices were acquired using the Active Breathing Coordinator device (ABC, Elekta Oncology Systems Ltd., UK). RESULTS: The volumes acquired with the ABC device were significantly smaller than the free-breathing volumes [23 % reduction of planning tumour volume (PTV), p = 0.002]. ABC allowed a reduction of all dosimetric parameters [2.28 % reduction of percentage volume of lung treated to a dose of ≥ 20 Gy (V20), p = 0.004; 10 % reduction of mean lung dose (MLD), p = 0.009]. Significant differences were found both in SRT and in 3D-CRT, in peripheral and apical lesions. CONCLUSION: In our experience, ABC has the potential to reduce lung toxicity in the treatment of lung cancer; alternatively, it can allow the prescribed dose to be increased while maintaining the same risk of lung toxicity.

Enhancing patient safety in radiotherapy: Implementation of a customized electronic checklist for radiation therapists.

Introduction: The radiotherapy workflow involves the collaboration of multiple professionals and the execution of several steps to results in an effective treatment. In this study, we described the clinical implementation of an electronic checklist, developed to standardize the process of the chart review prior to the first treatment fraction by the radiation therapists (RTTs). Materials and Methods: A customized electronic checklist was developed based on the recommendations of American Association of Physicists in Medicine (AAPM) Task Groups 275 and 315 and integrated into the Record and Verify System (RVS). The checklist consisted of 16 items requiring binary (yes/no) responses, with mandatory completion and review by RTTs prior to treatment. The utility of the checklist and its impact on workflow were assessed by analysing checklist reports, and by soliciting feedback to RTTs through an anonymized survey. Results: During the first trial phase, from June to November 2023, 285 checklists were completed with a 98% compilation rate and 94.4% review rate. Forty errors were detected, mainly due to missing signed treatment plans and absence of Beam's Eye View documentation. Ninety percent of detected errors were fixed before the treatment start. In 4 cases, the problem could not be fixed before the first fraction, resulting in a suboptimal first treatment. The feedback survey showed that RTTs described the checklist as useful, with minimal impact on workload, and supported its implementation. Discussion: The introduction of a customized electronic checklist improved the detection and correction of errors, thereby enhancing patient safety. The positive response from RTTs and the minimal impact on workflow underscore the value of the checklist as standard practice in radiotherapy departments.

Stereotactic body radiotherapy for cardiac and paracardiac metastases: University of Florence experience.

PURPOSE: This study sought to evaluate acute toxicity and local control in patients who underwent extracranial stereotactic body radiation therapy (SBRT) for paracardiac and cardiac metastatic lesions, defined as such when located at a maximum distance of 1 cm from the heart or inside its parenchyma. MATERIALS AND METHODS: Between January 2009 and May 2011, 16 patients with paracardiac and cardiac lesions were treated with SBRT. For dose specification, in 15 of 16 patients, the prescription dosage was 36 Gy in three fractions (70% isodose). In one patient, the target lesion was inside the heart, and the prescription dosage was 30 Gy in three fractions (70% isodose). RESULTS: Regarding response to stereotactic radiotherapy, we recorded one (6%) complete response (CR), six (37%) partial responses (PR), five (32%) stable disease (SD) and four (25%) local failures. Median interval to local failure was 5.2 (range, 3-12) months. The cause of death was distant progression of disease in all four patients. Compliance to treatment was excellent; no patient developed cardiological symptoms or electrocardiographic abnormalities, even months after SBRT. CONCLUSIONS: Results of our retrospective study indicate that SBRT represents a safe and effective treatment option for patients with cardiac and paracardiac metastases.

Updates on the APBI-IMRT-Florence Trial (NCT02104895) Technique: From the Intensity Modulated Radiation Therapy Trial to the Volumetric Modulated Arc Therapy Clinical Practice.

Several phase 3 trials have demonstrated partial breast irradiation noninferiority compared with whole breast irradiation in terms of local control and similar or reduced toxicity. During recent years, especially owing to the COVID-19 pandemic, a growing interest in 5-fraction regimens emerged. The APBI-IMRT-Florence trial (NCT02104895) schedule (30 Gy in 5 fractions) might represent an appealing treatment option, being both a safe and effective partial breast irradiation schedule, with long-term reported results. The aim of this report is to support planners interested in implementing this technique and to warrant equal access to postoperative radiation treatment for most early breast cancer patient candidates. We report the current delivery technique optimized from the original protocol and the updated dose constraints for plan optimization. We also report a statistical analysis of dosimetric parameters on 50 patients treated in consecutive fractions. Treatment-related toxic effects were assessed using the acute radiation morbidity scoring criteria and late radiation morbidity scoring scheme from the Radiation Therapy Oncology Group and the European Organisation for Research and Treatment of Cancer. The mean volume of ipsilateral breast was 731 cm3 (standard deviation ± 450; range, 151-2205) and the mean planning target volume (PTV) was 139 cm3 (standard deviation ± 48; range, 55-259). There was good correlation between ipsilateral breast V15Gy and the ratio between the PTV and ipsilateral breast volume (R2 = .911). At a median follow-up of 4.5 years, 32% of patients (n = 16) developed any grade 1 acute toxic effect. No grade >1 toxic effect was observed. Sixteen percent of patients (n = 8) developed any grade 1 late toxic effect. No grade >1 toxic effect was observed. Physician-assessed cosmesis was reported as excellent (84%), good (14%), and fair (2%). The schedule of 30 Gy in 5 consecutive fractions might represent a safe, easy-to-deliver, and cost-effective option for appropriately selected patients affected by early breast cancer.