Preoperative MRI radiomic analysis for predicting local tumor progression in colorectal liver metastases before microwave ablation

PURPOSE

Radiomics may aid in predicting prognosis in patients with colorectal liver metastases (CLM). Consistent data is available on CT, yet limited data is available on MRI. This study assesses the capability of MRI-derived radiomic features (RFs) to predict local tumor progression-free survival (LTPFS) in patients with CLMs treated with microwave ablation (MWA).

METHODS

All CLM patients with pre-operative Gadoxetic acid-MRI treated with MWA in a single institution between September 2015 and February 2022 were evaluated. Pre-procedural information was retrieved retrospectively. Two observers manually segmented CLMs on T2 and T1-Hepatobiliary phase (T1-HBP) scans. After inter-observer variability testing, 148/182 RFs showed robustness on T1-HBP, and 141/182 on T2 (ICC > 0.7).Cox multivariate analysis was run to establish clinical (CLIN-mod), radiomic (RAD-T1, RAD-T2), and combined (COMB-T1, COMB-T2) models for LTPFS prediction.

RESULTS

Seventy-six CLMs (43 patients) were assessed. Median follow-up was 14 months. LTP occurred in 19 lesions (25%).CLIN-mod was composed of minimal ablation margins (MAMs), intra-segment progression and primary tumor grade and exhibited moderately high discriminatory power in predicting LTPFS (AUC = 0.89, p = 0.0001). Both RAD-T1 and RAD-T2 were able to predict LTPFS: (RAD-T1: AUC = 0.83, p = 0.0003; RAD-T2: AUC = 0.79, p = 0.001). Combined models yielded the strongest performance (COMB-T1: AUC = 0.98, p = 0.0001; COMB-T2: AUC = 0.95, p = 0.0003). Both combined models included MAMs and tumor regression grade; COMB-T1 also featured 10th percentile of signal intensity, while tumor flatness was present in COMB-T2.

CONCLUSION

MRI-based radiomic evaluation of CLMs is feasible and potentially useful for LTP prediction. Combined models outperformed clinical or radiomic models alone for LTPFS prediction.

Skin dose-volume predictors of moderate-severe late side effects after whole breast radiotherapy

BACKGROUND

Toxicity after whole breast Radiotherapy is a relevant issue, impacting the quality-of-life of a not negligible number of patients. We aimed to develop a Normal Tissue Complication Probability (NTCP) model predicting late toxicities by combining dosimetric parameters of the breast dermis and clinical factors.

METHODS

The skin structure was defined as the outer CT body contour's 5 mm inner isotropic expansion. It was retrospectively segmented on a large mono-institutional cohort of early-stage breast cancer patients enrolled between 2009 and 2017 (n = 1066). Patients were treated with tangential-field RT, delivering 40 Gy in 15 fractions to the whole breast. Toxicity was reported during Follow-Up (FU) using SOMA/LENT scoring. The study endpoint was moderate-severe late side effects consisting of Fibrosis-Atrophy-Telangiectasia-Pain (FATP G ≥ 2) developed within 42 months after RT completion. A machine learning pipeline was designed with a logistic model combining clinical factors and absolute skin DVH (cc) parameters as output.

RESULTS

The FATP G2 + rate was 3.8 %, with 40/1066 patients experiencing side effects. After the preprocessing of variables, a cross-validation was applied to define the best-performing model. We selected a 4-variable model with Post-Surgery Cosmetic alterations (Odds Ratio, OR = 7.3), Aromatase Inhibitors (as a protective factor with OR = 0.45), V20 Gy (50 % of the prescribed dose, OR = 1.02), and V42 Gy (105 %, OR = 1.09). Factors were also converted into an adjusted V20Gy.

CONCLUSIONS

The association between late reactions and skin DVH when delivering 40 Gy/15 fr was quantified, suggesting an independent role of V20 and V42. Few clinical factors heavily modulate the risk.

Inter-institutional variability of knowledge-based plan prediction of left whole breast irradiation

PURPOSE

Within a multi-institutional project, we aimed to assess the transferability of knowledge-based (KB) plan prediction models in the case of whole breast irradiation (WBI) for left-side breast irradiation with tangential fields (TF).

METHODS

Eight institutions set KB models, following previously shared common criteria. Plan prediction performance was tested on 16 new patients (2 pts per centre) extracting dose-volume-histogram (DVH) prediction bands of heart, ipsilateral lung, contralateral lung and breast. The inter-institutional variability was quantified by the standard deviations (SDint) of predicted DVHs and mean-dose (Dmean). The transferability of models, for the heart and the ipsilateral lung, was evaluated by the range of geometric Principal Component (PC1) applicability of a model to test patients of the other 7 institutions.

RESULTS

SDint of the DVH was 1.8 % and 1.6 % for the ipsilateral lung and the heart, respectively (20 %-80 % dose range); concerning Dmean, SDint was 0.9 Gy and 0.6 Gy for the ipsilateral lung and the heart, respectively (<0.2 Gy for contralateral organs). Mean predicted doses ranged between 4.3 and 5.9 Gy for the ipsilateral lung and 1.1-2.3 Gy for the heart. PC1 analysis suggested no relevant differences among models, except for one centre showing a systematic larger sparing of the heart, concomitant to a worse PTV coverage, due to high priority in sparing the left anterior descending coronary artery.

CONCLUSIONS

Results showed high transferability among models and low inter-institutional variability of 2% for plan prediction. These findings encourage the building of benchmark models in the case of TF-WBI.

Impact of low skeletal muscle mass in oropharyngeal cancer patients treated with radical chemo-radiotherapy: A mono-institutional experience

AIMS

Low skeletal muscle mass index (SMI) has recently emerged as an independent prognostic factor in oncological patients and it is linked with poor survival and higher treatment toxicity. The present study aims to determine the possible impact of low SMI on survival and acute toxicity in oropharyngeal patients.

METHODS

Seventy-six patients with locally advanced oropharyngeal squamous cell carcinoma (stage III-IVC) were treated in our institution with Helical TomoTherapy® (HT - Accuray, Maddison, WI, USA) between 2005 and 2021. All patients received concomitant platinum-based chemotherapy (CT) (at least 200 mg/m2). The SMI was determined using the calculation of cross-sectional area at C3. Twenty patients (26%) presented pre-treatment low SMI, according to Chargi definitions.

RESULTS

All patients concluded the treatment. Thirteen patients with low SMI (65%) and 22 patients with normal SMI (39%) presented acute toxicity greater than or equal to grade 3, but this difference was not statistically significant (p-value = 0.25). Overall survival was analyzed in 65 patients, excluding those who finished CT-RT less than six months before the analysis. Overall survival was significantly lower in low SMI versus normal SMI patients (p-value = 0.035). Same difference was observed in N0-N2a patients, suggesting an important role of SMI also in lower nodal burden and putatively better prognosis.

CONCLUSIONS

Although the results are limited to a small population, our case series has the advantage to be very homogeneous in patients and treatment characteristics. In our setting, SMI demonstrated a crucial impact on overall survival. Further investigation with larger samples is necessary to confirm our results to improve patient outcomes.

Comparing Performances of Predictive Models of Toxicity after Radiotherapy for Breast Cancer Using Different Machine Learning Approaches

PURPOSE

Different ML models were compared to predict toxicity in RT on a large cohort (n = 1314).

METHODS

The endpoint was RTOG G2/G3 acute toxicity, resulting in 204/1314 patients with the event. The dataset, including 25 clinical, anatomical, and dosimetric features, was split into 984 for training and 330 for internal tests. The dataset was standardized; features with a high p-value at univariate LR and with Spearman ρ>0.8 were excluded; synthesized data of the minority were generated to compensate for class imbalance. Twelve ML methods were considered. Model optimization and sequential backward selection were run to choose the best models with a parsimonious feature number. Finally, feature importance was derived for every model.

RESULTS

The model's performance was compared on a training-test dataset over different metrics: the best performance model was LightGBM. Logistic regression with three variables (LR3) selected via bootstrapping showed performances similar to the best-performing models. The AUC of test data is slightly above 0.65 for the best models (highest value: 0.662 with LightGBM).

CONCLUSIONS

No model performed the best for all metrics: more complex ML models had better performances; however, models with just three features showed performances comparable to the best models using many (n = 13-19) features.

Single Versus Fractionated Gamma Knife Radiosurgery for Nonfunctioning Pituitary Adenomas Close to the Optic Pathway: A Multicenter Propensity Score Matched Study

BACKGROUND AND OBJECTIVES

Gamma Knife radiosurgery (GKRS), typically administered in a single session (S-GKRS), is an effective treatment for nonfunctioning pituitary adenoma (NFPA). For lesions close to the optic pathway, the use of hypofractionated radiosurgery is growing. This study seeks to compare the results of S-GKRS vs fractionated-GKRS (F-GKRS) for NFPAs adjacent to the optic pathway.

METHODS

Two cohorts of patients with residual or recurrent NFPAs in contact to the optic pathway were retrospectively included in this study: (1) a group of patients who underwent a 3-day course of F-GKRS in Europe and (2) a group of patients treated with S-GKRS in the United States. A propensity score matching (ratio 1:1) was carried out to obtain and compare 2 homogeneous groups of patients with NFPA.

RESULTS

A total of 84 patients were included for analysis (42 in the S-GKRS cohort and 42 in the F-GKRS group). The 2 cohorts did not differ for age, sex, number of previous surgical procedure, tumor volume, and follow-up. The mean follow-up was 60.2 ± 37.0 months and 62.4 ± 37.4 months for F-GKRS and S-GKRS cohort, respectively (P = .38). The overall tumor control at last follow-up was achieved in 95.2% and 92.9% of patients in F-GKRS and S-GKRS, respectively (P = .64). The 1-year, 3-year, 5-year, and 7-year progression-free survival rate after F-GKRS was 100%, 97.1%, 97.1%, and 91%, respectively. In the S-GKRS sample, progression-free survival rates were 100%, 100%, 92.5%, and 92.5% at 1, 3, 5, and 7 years after treatment, respectively. Two patients (4.7%) from the F-GKRS cohort and 2 (4.7%) from the S-GKRS cohort sustained visual worsening after radiosurgery (P = 1.0).

CONCLUSION

In the management of NFPAs adjacent to the optic pathway both F-GKRS and S-GKRS had comparable outcomes and risks at 7 years. Future prospective studies including larger cohorts with longer follow-up are needed to confirm our results.

Limited impact of discretization/interpolation parameters on the predictive power of CT radiomic features in a surgical cohort of pancreatic cancer patients

PURPOSE

To explore the variation of the discriminative power of CT (Computed Tomography) radiomic features (RF) against image discretization/interpolation in predicting early distant relapses (EDR) after upfront surgery.

MATERIALS AND METHODS

Data of 144 patients with pre-surgical high contrast CT were processed consistently with IBSI (Image Biomarker Standardization Initiative) guidelines. Image interpolation/discretization parameters were intentionally changed, including cubic voxel size (0.21-27 mm³) and binning (32-128 grey levels) in a 15 parameter's sets. After excluding RF with poor inter-observer delineation agreement (ICC < 0.80) and not negligible inter-scanner variability, the variation of 80 RF against discretization/interpolation was first quantified. Then, their ability in classifying patients with early distant relapses (EDR, < 10 months, previously assessed at the first quartile value of time-to-relapse) was investigated in terms of AUC (Area Under Curve) variation for those RF significantly associated to EDR.

RESULTS

Despite RF variability against discretization/interpolation parameters was large and only 30/80 RF showed %COV < 20 (%COV = 100*STDEV/MEAN), AUC changes were relatively limited: for 30 RF significantly associated with EDR (AUC values around 0.60-0.70), the mean values of SD of AUC variability and AUC range were 0.02 and 0.05 respectively. AUC ranges were between 0.00 and 0.11, with values ≤ 0.05 in 16/30 RF. These variations were further reduced when excluding the extreme values of 32 and 128 for grey levels (Average AUC range 0.04, with values between 0.00 and 0.08).

CONCLUSIONS

The discriminative power of CT RF in the prediction of EDR after upfront surgery for pancreatic cancer is relatively invariant against image interpolation/discretization within a large range of voxel sizes and binning.

Knowledge-based plan optimization for prostate SBRT delivered with CyberKnife according to RTOG0938 protocol

PURPOSE

To extend the knowledge-based (KB) automatic planning approach to CyberKnife in the case of Stereotactic Body Radiation Therapy (SBRT) for prostate cancer.

METHODS

Seventy-two clinical plans of patients treated according to the RTOG0938 protocol (36.25 Gy/5fr) with CyberKnife were exported from the CyberKnife system to Eclipse to train a KB-model using the Rapid Plan tool. The KB approach provided dose-volume objectives for specific OARs only and not PTV. Bladder, rectum and femoral heads were considered in the model. The KB-model was successfully trained on 51 plans and then validated on 20 new patients. A KB-based template was tuned in the Precision system for both sequential optimization (SO) and VOLO optimization algorithms. Plans of the validation group were re-optimized (KB-TP) using both algorithms without any operator intervention and compared against the original plans (TP) in terms of OARs/PTV dose-volume parameters. Paired Wilcoxon signed-rank tests were performed to assess statistically significant differences (p < 0.05).

RESULTS

Regarding SO, automatic KB-TP plans were generally better than or equivalent to TP plans. PTVs V95% was slightly worse while OARs sparing for KB-TP was significantly improved. Regarding VOLO optimization, the PTVs coverage was significantly better for KB-TP while there was a limited worsening in the rectum. A significant improvement was observed in the bladder in the range of low-intermediate doses.

CONCLUSIONS

An extension of the KB optimization approach to the CyberKnife system has been successfully developed and validated in the case of SBRT prostate cancer.

External validation of an 18F-FDG-PET radiomic model predicting survival after radiotherapy for oropharyngeal cancer

PURPOSE/OBJECTIVE

The purpose of the study is to externally validate published ¹⁸F-FDG-PET radiomic models for outcome prediction in patients with oropharyngeal cancer treated with chemoradiotherapy.

MATERIAL/METHODS

Outcome data and pre-radiotherapy PET images of 100 oropharyngeal cancer patients (stage IV:78) treated with concomitant chemotherapy to 66-69 Gy/30 fr were available. Tumors were segmented using a previously validated semi-automatic method; 450 radiomic features (RF) were extracted according to IBSI (Image Biomarker Standardization Initiative) guidelines. Only one model for cancer-specific survival (CSS) prediction was suitable to be independently tested, according to our criteria. This model, in addition to HPV status, SUVmean and SUVmax, included two independent meta-factors (F_i), resulting from combining selected RF clusters. In a subgroup of 66 patients with complete HPV information, the global risk score R was computed considering the original coefficients and was tested by Cox regression as predictive of CSS. Independently, only the radiomic risk score R_F derived from F_i was tested on the same subgroup to learn about the radiomics contribution to the model. The metabolic tumor volume (MTV) was also tested as a single predictor and its prediction performances were compared to the global and radiomic models. Finally, the validation of MTV and the radiomic score R_F were also tested on the entire dataset.

RESULTS

Regarding the analysis of the subgroup with HPV information, with a median follow-up of 41.6 months, seven patients died due to cancer. R was confirmed to be associated to CSS (p value = 0.05) with a C-index equal 0.75 (95% CI=0.62-0.85). The best cut-off value (equal to 0.15) showed high ability in patient stratification (p=0.01, HR=7.4, 95% CI=1.6-11.4). The 5-year CSS for R were 97% (95% CI: 93-100%) vs 74% (56-92%) for low- and high-risk groups, respectively. R_F and MTV alone were also significantly associated to CSS for the subgroup with an almost identical C-index. According to best cut-off value (R_F>0.12 and MTV>15.5cc), the 5-year CSS were 96% (95% CI: 89-100%) vs 65% (36-94%) and 97% (95% CI: 88-100%) vs 77% (58-93%) for RF and MTV, respectively. Results regarding RF and MTV were confirmed in the overall group.

CONCLUSION

A previously published PET radiomic model for CSS prediction was independently validated. Performances of the model were similar to the ones of using only the MTV, without improvement of prediction accuracy.

Stomach and duodenum dose-volume constraints for locally advanced pancreatic cancer patients treated in 15 fractions in combination with chemotherapy

Purpose

To assess dosimetry predictors of gastric and duodenal toxicities for locally advanced pancreatic cancer (LAPC) patients treated with chemo-radiotherapy in 15 fractions.

Methods

Data from 204 LAPC patients treated with induction+concurrent chemotherapy and radiotherapy (44.25 Gy in 15 fractions) were available. Forty-three patients received a simultaneous integrated boost of 48-58 Gy. Gastric/duodenal Common Terminology Criteria for Adverse Events v. 5 (CTCAEv5) Grade ≥2 toxicities were analyzed. Absolute/% duodenal and stomach dose-volume histograms (DVHs) of patients with/without toxicities were compared: the most predictive DVH points were identified, and their association with toxicity was tested in univariate and multivariate logistic regressions together with near-maximum dose (D_0.03) and selected clinical variables.

Results

Toxicity occurred in 18 patients: 3 duodenal (ulcer and duodenitis) and 10 gastric (ulcer and stomatitis); 5/18 experienced both. At univariate analysis, V44cc (duodenum: p = 0.02, OR = 1.07; stomach: p = 0.01, OR = 1.12) and D_0.03 (p = 0.07, OR = 1.19; p = 0.008, OR = 1.12) were found to be the most predictive parameters. Stomach/duodenum V44Gy and stomach D_0.03 were confirmed at multivariate analysis and found to be sufficiently robust at internal, bootstrap-based validation; the results regarding duodenum D_0.03 were less robust. No clinical variables or %DVH was significantly associated with toxicity. The best duodenum cutoff values were V44Gy < 9.1 cc (and D_0.03 < 47.6 Gy); concerning the stomach, they were V44Gy < 2 cc and D_0.03 < 45 Gy. The identified predictors showed a high negative predictive value (>94%).

Conclusion

In a large cohort treated with hypofractionated radiotherapy for LAPC, the risk of duodenal/gastric toxicities was associated with duodenum/stomach DVH. Constraining duodenum V44Gy < 9.1 cc, stomach V44Gy < 2 cc, and stomach D_0.03 < 45 Gy should keep the toxicity rate at approximately or below 5%. The association with duodenum D_0.03 was not sufficiently robust due to the limited number of events, although results suggest that a limit of 45-46 Gy should be safe.

Radioluminescence imaging feasibility for robotic radiosurgery field size quality assurance

PURPOSE

To investigate the feasibility of radioluminescence imaging (RLI) as a novel 2D quality assurance (QA) dosimetry system for CyberKnife®.

METHODS

We developed a field size measurement system based on a commercial complementary metal oxide semiconductor (CMOS) camera facing a radioluminescence screen located at the isocenter normal to the beam axis. The radioluminescence light collected by a lens was used to measure 2D dose distributions. An image transformation procedure, based on two reference phantoms, was developed to correct for projective distortion due to the angle (15°) between the optical and beam axis. Dose profiles were measured for field sizes ranging from 5 mm to 60 mm using fixed circular and iris collimators and compared against gafchromic (GC) film. The corresponding full width at half maximum (FWHM) was measured using RLI and benchmarked against GC film. A small shift in the source-to-surface distance (SSD) of the measurement plane was intentionally introduced to test the sensitivity of the RLI system to field size variations. To assess reproducibility, the entire RLI procedure was tested by acquiring the 60 mm circle field three times on two consecutive days.

RESULTS

The implemented procedure for perspective image distortion correction showed improvements of up to 1 mm using the star phantom against the square phantom. The FWHM measurements using the RLI system indicated a strong agreement with GC film with maximum absolute difference equal to 0.131 mm for fixed collimators and 0.056 mm for the iris. A 2D analysis of RLI with respect to GC film showed that the differences in the central region are negligible, while small discrepancies are in the penumbra region. Changes in field sizes of 0.2 mm were detectable by RLI. Repeatability measurements of the beam FWHM have shown a standard deviation equal to 0.11 mm.

CONCLUSIONS

The first application of a RLI approach for CyberKnife® field size measurement was presented and tested. Results are in agreement with GC film measurements. Spatial resolution and immediate availability of the data indicate that RLI is a feasible technique for robotic radiosurgery QA.

Radiation exposure during modern therapeutic endoscopic ultrasound procedures and standard alternatives

Background and study aims  Therapeutic EUS (t-EUS) is increasingly being adopted in clinical practice in tertiary referral centers; however, little is known about radiation exposure (RE) metrics and diagnostic reference limits for it. Methods  Kerma-area product (KAP [Gy·cm ² ]), Air Kerma and fluoroscopy time were retrospectively evaluated for all consecutive t-EUS procedures performed in San Raffaele Institute between 2019 and 2021. For EUS-guided choledochoduodenostomies (EUS-CDS) and gastroenterostomies (EUS-GE), an equal number of endoscopic retrograde cholangiopancreatographies (ERCPs) plus metal stenting and duodenal stents were included respectively for comparison. Results  Data from 141 t-EUS procedures were retrieved (49 % pancreatic cancer, 38 % peripancreatic fluid collections). EUS-CDS (N = 44) were mainly performed fluoroless, while ERCPs required a significantly higher RE (KAP = 25 [17-55], P < 0.0001). Fluid collection drainage (EUS-FCD) with lumen apposing metal stents (LAMS, N = 26) were performed fluoroless, while EUS-FCD with double-pigtail plastic stents (DPPS, N = 28) required higher RE (KAP = 23 [13-45]). EUS-guided gallbladder drainage (EUS-GBD, N = 6) required scarce RE (KAP = 9 [3-21]) for coaxial DPPS placement. EUS-GE (N = 27) required higher RE than duodenal stenting (KAP = 44 [28-88] versus 29 [19-46], P = 0.03). EUS-guided hepaticogastrostomies (EUS-HGS, N = 10) had the highest RE among t-EUS procedures (KAP = 81 [49-123]). Procedure complexity or intervening complications were evaluated and resulted in higher RE within each procedure. Conclusions  t-EUS procedures have different RE ( P  < 0.000001). EUS-CDS, EUS-GBD, and EUS-FCD with LAMS can be performed with no-to-mild radioscopy, unlike standard alternatives. However, radioscopy remains essential in case of technical difficulties or complications. EUS-GE and EUS-HGS involve a high RE. Endoscopists involved in t-EUS might experience RE higher than category standards, which indicates a need for increased awareness and personalized preventive measures.

Atlas-Based Lung Segmentation Combined With Automatic Densitometry Characterization In COVID-19 Patients: Training, Validation And First Application In A Longitudinal Study

Purpose

To develop and validate an automated segmentation tool for COVID-19 lung CTs. To combine it with densitometry information in identifying Aerated, Intermediate and Consolidated Volumes in admission (CT1) and follow up CT (CT3).

Materials and Methods

An Atlas was trained on manually segmented CT1 of 250 patients and validated on 10 CT1 of the training group, 10 new CT1 and 10 CT3, by comparing DICE index between automatic (AUTO), automatic-corrected (AUTOMAN) and manual (MAN) contours. A previously developed automatic method was applied on HU lung density histograms to quantify Aerated, Intermediate and Consolidated Volumes. Volumes of subregions in validation CT1 and CT3 were quantified for each method.

Results

In validation CT1/CT3, manual correction of automatic contours was not necessary in 40% of cases. Mean DICE values for both lungs were 0.94 for AUTOVsMAN and 0.96 for AUTOMANVsMAN. Differences between Aerated and Intermediate Volumes quantified with AUTOVsMAN contours were always < 6%. Consolidated Volumes showed larger differences (mean: −95 ± 72 cc). If considering AUTOMANVsMAN volumes, differences got further smaller for Aerated and Intermediate, and were drastically reduced for consolidated Volumes (mean: −36 ± 25 cc). The average time for manual correction of automatic lungs contours on CT1 was 5 ± 2 min.

Conclusions

An Atlas for automatic segmentation of lungs in COVID-19 patients was developed and validated. Combined with a previously developed method for lung densitometry characterization, it provides a fast, operator-independent way to extract relevant quantitative parameters with minimal manual intervention.

Fabrication of 3D printed patient-derived anthropomorphic breast phantoms for mammography and digital breast tomosynthesis: Imaging assessment with clinical X-ray spectra

PURPOSE

To design, fabricate and characterize 3D printed, anatomically realistic, compressed breast phantoms for digital mammography (DM) and digital breast tomosynthesis (DBT) x-ray imaging.

MATERIALS

We realized 3D printed phantoms simulating healthy breasts, via fused deposition modeling (FDM), with a layer resolution of 0.1 mm and 100% infill density, using a dual extruder printer. The digital models were derived from a public dataset of segmented clinical breast computed tomography scans. Three physical phantoms were printed in polyethylene terephthalate (PET), acrylonitrile-butadiene-styrene (ABS), or in polylactic-acid (PLA) materials, using ABS as a substitute for adipose tissue, and PLA or PET filaments for replicating glandular and skin tissues. 3D printed phantoms were imaged at three clinical centers with DM and DBT scanners, using typical spectra. Anatomical noise of the manufactured phantoms was evaluated via the estimates of the β parameter both in DM images and in images acquired via a clinical computed tomography (CT) scanner.

RESULTS

DM and DBT phantom images showed an inner texture qualitatively similar to the images of a clinical DM or DBT exam, suitably reproducing the glandular structure of their computational phantoms. β parameters evaluated in DM images of the manufactured phantoms ranged between 2.84 and 3.79; a lower β was calculated from the CT scan.

CONCLUSIONS

FDM 3D printed compressed breast phantoms have been fabricated using ABS, PLA and PET filaments. DM and DBT images with clinical x-ray spectra showed realistic textures. These phantoms appear promising for clinical applications in quality assurance, image quality and dosimetry assessments.

Statement of the Italian Association of Medical Physics (AIFM) task group on radiation dose monitoring systems

The evaluation of radiation burden in vivo is crucial in modern radiology as stated also in the European Directive 2013/59/Euratom—Basic Safety Standard. Although radiation dose monitoring can impact the justification and optimization of radiological procedure, as well as effective patient communication, standardization of radiation monitoring software is far to be achieved. Toward this goal, the Italian Association of Medical Physics (AIFM) published a report describing the state of the art and standard guidelines in radiation dose monitoring system quality assurance. This article reports the AIFM statement about radiation dose monitoring systems (RDMSs) summarizing the different critical points of the systems related to Medical Physicist Expert (MPE) activities before, during, and after their clinical implementation. In particular, the article describes the general aspects of radiation dose data management, radiation dose monitoring systems, data integrity, and data responsibilities. Furthermore, the acceptance tests that need to be implemented and the most relevant dosimetric data for each radiological modalities are reported under the MPE responsibility.

Decommissioning procedure and induced activation levels, calculations and measurements in an 18 MeV medical cyclotron

The present article describes the decommissioning of a self-shielded 18 MeV medical cyclotron IBA Cyclone 18/9 after 14 years of operation. A Monte Carlo simulation of the possible nuclear reactions was performed in order to plan the decommissioning activities. During the cyclotron dismantling, the activities of the cyclotron components, concrete wall and floor samples were measured. Residual activities were analysed by means of an HPGe detector and liquid scintillation counting, and compared with simulation data. Dosimetry of the staff involved in the decommissioning procedure was monitored by individual TL dosimeters and/or digital dosimeter. The cyclotron component analysis confirmed the presence of gamma and pure beta emitters,²²Na,⁵⁴Mn,⁶⁰Co,⁶⁵Zn,²⁰⁷Bi,⁵⁵Fe,⁶³Ni at different values of specific activity, depending on the positioning of the sample point and on the alloy of the sampled part. In these components the presence of gamma and pure beta emitters was measured 5 years after the shutdown at levels far above clearance limits as defined by the 'Recommended radiological protection criteria for the recycling of metals from the dismantling of nuclear installations' (RP89) guidelines. The simulation, carried out by FLUKA Code (version 2020.0.5) on the cyclotron components, provided good agreement with measurements, with a maximum discrepancy of the same order as the uncertainties. Four engineers of the cyclotron maintenance staff were involved in the dismounting of the hottest components and rigging of the cyclotron in the deposit 6 months after shutdown and two engineers were involved during the drilling phase 3.5 years after shutdown. The measured dose from external exposure of the involved staff was lower than 100μSv person^-1during the first phase and lower than 20μSv person^-1during the final drilling phase. Measured doses from intake were negligible. In conclusion, the decommissioning of the 18 MeV cyclotron does not represent a risk for the involved staff, but, due to the presence of long-lived radioisotopes, the cyclotron components are to be treated as low level radioactive waste, and stored in an authorised storage area for at least 25 years after shutdown.

Breast radiotherapy with kilovoltage photons and gold nanoparticles as radiosensitizer: An in vitro study

Purpose

We investigated the dose enhancement and internalization of gold nanoparticles (AuNPs) used as a radiosensitizer agent for rotational radiotherapy of breast cancer using a kilovoltage (kV) X‐ray beam.

Methods

Human breast cancer cells MDA‐MB‐231 were incubated with or without 100 μg/mL (4.87 nM) or 200 μg/mL (9.74 nM) 15 nm AuNPs and irradiated with 100 kV, 190 kV, or 6 MV X‐rays. To assess the toxicity of the AuNPs, we performed a Sulforhodamine B assay. Using atomic absorption spectroscopy, scanning electron microscopy, transmission electron microscopy, and time‐lapse optical microscopy (rate of 2 frames per minute), we carried out a quantitative assessment of the amount of gold internalized by MDA‐MB‐231 cells and a characterization of the static and dynamical aspects of this internalization process.

Results

No effect of AuNPs alone was shown on cell viability. Time‐lapse optical microscopy showed for the first time AuNPs cellular uptake and the dynamics of AuNPs internalization. Electron microscopy demonstrated AuNPs localization in endosomal vesicles, preferentially in the perinuclear region. After irradiation at doses up to 2 Gy, cell survival fraction curves showed increased mortality with AuNPs, with respect to irradiation without AuNPs. The highest effect of radioenhancement by AuNPs (at 9.74 nM AuNPs concentration) was observed at 190 kV showing a dose enhancement factor of 1.33 ± 0.06 (1.34 ± 0.02 at 100 kV), while at 6 MV it was 1.14 ± 0.06.

Conclusions

The observed radio‐sensitization effect is promising for future radio‐enhanced kV radiotherapy of breast cancer and quantitatively in the order of previous observations for 15 nm AuNPs. These results of a significant dose enhancement were obtained at 15 nm AuNPs concentration as low as several nanomolar units, at dose levels typical of a single dose fraction in a radiotherapy session. Dynamical behavior of the 3D spatial distribution of 15 nm AuNPs outside the nucleus of single breast cancer cell was observed, with possible implications for future models of AuNPs sensitization.

Ten Year Results of Extensive Nodal Radiotherapy and Moderately Hypofractionated Simultaneous Integrated Boost in Unfavorable Intermediate-, High-, and Very High-Risk Prostate Cancer

Simple Summary

Several phase III randomized trials of moderate hypofractionation, including a higher proportion of high-risk prostate cancer patients treated only to the prostate, failed to demonstrate the superiority of hypofractionated regimens. There is only one randomized phase III trial, of moderately hypofractionated high-dose radiotherapy to the prostate-only versus pelvic irradiation and prostate boost, with a sufficiently long follow-up. It demonstrated better biochemical and disease-free survival when lymph nodal radiotherapy was added. Here we present the 10-year results of our experience based on an Institutional protocol adopted after a phase I–II study, on patients with unfavorable intermediate- (UIR), high- (HR), and very high-risk (VHR) prostate cancer (PCa) treated with pelvic lymph nodal irradiation (WPRT) and moderately hypofractionated high-dose (HD) simultaneous integrated boost (SIB) to the prostate. Prognostic factors for relapse, as well as acute and late gastro-intestinal (GI) and genito-urinary (GU) toxicity were also analyzed.

Abstract

Aims: To report 10-year outcomes of WPRT and HD moderately hypofractionated SIB to the prostate in UIR, HR, and VHR PCa. Methods: From 11/2005 to 12/2015, 224 UIR, HR, and VHR PCa patients underwent WPRT at 51.8 Gy/28 fractions and SIB at 74.2 Gy (EQD2 88 Gy) to the prostate. Androgen deprivation therapy (ADT) was prescribed in up to 86.2% of patients. Results: Median follow-up was 96.3 months (IQR: 71–124.7). Median age was 75 years (IQR: 71.3–78.1). At last follow up, G3 GI–GU toxicity was 3.1% and 8%, respectively. Ten-year biochemical relapse-free survival (bRFS) was 79.8% (95% CI: 72.3–88.1%), disease-free survival (DFS) 87.8% (95% CI: 81.7–94.3%), overall survival (OS) 65.7% (95% CI: 58.2–74.1%), and prostate cancer-specific survival (PCSS) 94.9% (95% CI: 91.0–99.0%). Only two patients presented local relapse. At univariate analysis, VHR vs. UIR was found to be a significant risk factor for biochemical relapse (HR: 2.8, 95% CI: 1.17–6.67, p = 0.021). After model selection, only Gleason Score ≥ 8 emerged as a significant factor for biochemical relapse (HR = 2.3, 95% CI: 1.12–4.9, p = 0.023). Previous TURP (HR = 3.5, 95% CI: 1.62–7.54, p = 0.001) and acute toxicity ≥ G2 (HR = 3.1, 95% CI = 1.45–6.52, p = 0.003) were significant risk factors for GU toxicity ≥ G3. Hypertension was a significant factor for GI toxicity ≥ G3 (HR = 3.63, 95% CI: 1.06–12.46, p = 0.041). ADT (HR = 0.31, 95% CI: 0.12–0.8, p = 0.015) and iPsa (HR = 0.37, 95% CI: 0.16–0.83, p = 0.0164) played a protective role. Conclusions: WPRT and HD SIB to the prostate combined with long-term ADT, in HR PCa, determine good outcomes with acceptable toxicity.

Prediction of Early Distant Recurrence in Upfront Resectable Pancreatic Adenocarcinoma: A Multidisciplinary, Machine Learning-Based Approach

Simple Summary

If pancreatic adenocarcinoma is assessed to be technically resectable, curative surgery is still suggested as the primary treatment option; however, the recurrence rate can be very high even in this selected population. The aim of our retrospective study was to develop a preoperative model to accurately stratify upfront resectable patients according to the risk of early distant disease relapse after surgery (<12 months from index procedure). Through a machine learning-based approach, we identified one biochemical marker (serum level of CA19.9), one radiological finding (necrosis) and one radiomic feature (SurfAreaToVolumeRatio), all significantly associated with the early resurge of distant recurrence. A model composed of these three variables only allowed identification of those patients at high risk for early distant disease relapse (50% chance of developing metastases within 12 months after surgery), who would benefit from neoadjuvant chemotherapy instead of upfront surgery.

Abstract

Despite careful selection, the recurrence rate after upfront surgery for pancreatic adenocarcinoma can be very high. We aimed to construct and validate a model for the prediction of early distant recurrence (<12 months from index surgery) after upfront pancreaticoduodenectomy. After exclusions, 147 patients were retrospectively enrolled. Preoperative clinical and radiological (CT-based) data were systematically evaluated; moreover, 182 radiomics features (RFs) were extracted. Most significant RFs were selected using minimum redundancy, robustness against delineation uncertainty and an original machine learning bootstrap-based method. Patients were split into training (n = 94) and validation cohort (n = 53). Multivariable Cox regression analysis was first applied on the training cohort; the resulting prognostic index was then tested in the validation cohort. Clinical (serum level of CA19.9), radiological (necrosis), and radiomic (SurfAreaToVolumeRatio) features were significantly associated with the early resurge of distant recurrence. The model combining these three variables performed well in the training cohort (p = 0.0015, HR = 3.58, 95%CI = 1.98–6.71) and was then confirmed in the validation cohort (p = 0.0178, HR = 5.06, 95%CI = 1.75–14.58). The comparison of survival curves between low and high-risk patients showed a p-value <0.0001. Our model may help to better define resectability status, thus providing an actual aid for pancreatic adenocarcinoma patients’ management (upfront surgery vs. neoadjuvant chemotherapy). Independent validations are warranted.

Replacing Manual Planning of Whole Breast Irradiation With Knowledge-Based Automatic Optimization by Virtual Tangential-Fields Arc Therapy

Purpose

To implement Knowledge Based (KB) automatic planning for right and left-sided whole breast treatment through a new volumetric technique (ViTAT, Virtual Tangential-fields Arc Therapy) mimicking conventional tangential fields (TF) irradiation.

Materials and Method

A total of 193 clinical plans delivering TF with wedged or field-in-field beams were selected to train two KB-models for right(R) and left(L) sided breast cancer patients using the RapidPlan (RP) tool implemented in the Varian Eclipse system. Then, a template for ViTAT optimization, incorporating individual KB-optimized constraints, was interactively fine-tuned. ViTAT plans consisted of four arcs (6 MV) with start/stop angles consistent with the TF geometry variability within our population; the delivery was completely blocked along the arcs, apart from the first and last 20° of rotation for each arc. Optimized fine-tuned KB templates for automatic plan optimization were generated. Validation tests were performed on 60 new patients equally divided in R and L breast treatment: KB automatic ViTAT-plans (KB-ViTAT) were compared against the original TF plans in terms of OARs/PTVs dose-volume parameters. Wilcoxon-tests were used to assess the statistically significant differences.

Results

KB models were successfully generated for both L and R sides. Overall, 1(3%) and 7(23%) out of 30 automatic KB-ViTAT plans were unacceptable compared to TF for R and L side, respectively. After the manual refinement of the start/stop angles, KB-ViTAT plans well fitted TF-performances for these patients as well. PTV coverage was comparable, while PTV D_1% was improved with KB-ViTAT by R:0.4/L:0.2 Gy (p < 0.05); ipsilateral OARs D_mean were similar with a slight (i.e., few % volume) improvement/worsening in the 15–35 Gy/2–15 Gy range, respectively. KB-ViTAT better spared contralateral OARs: D_mean of contralateral OARs was 0.1 Gy lower (p < 0.05); integral dose was R:5%/L:8% lower (p < 0.05) than TF. The overall time for the automatic plan optimization and final dose calculation was 12 ± 2 minutes.

Conclusions

Fully automatic KB-optimization of ViTAT can efficiently replace manually optimized TF planning for whole breast irradiation. This approach was clinically implemented in our institute and may be suggested as a large-scale strategy for efficiently replacing manual planning with large sparing of time, elimination of inter-planner variability and of, seldomly occurring, sub-optimal manual plans.

Gamma Knife radiosurgery for cluster-tic syndrome unresponsive to medical treatment: illustrative case

BACKGROUND

Cluster-tic syndrome is a disorder characterized by the coexistence of symptoms related to both cluster headache and trigeminal neuralgia. Etiopathogenesis is not yet well defined. Medical treatment, including drugs for both cluster headache and trigeminal neuralgia, is the first therapeutic choice, whereas more invasive treatments are indicated in the case of pharmacological therapy failure or in the presence of drug side effects. To date, no randomized and/or large cohort trials describing Gamma Knife radiosurgery (GKRS) for cluster-tic syndrome are available, probably due to the syndrome’s rarity.

OBSERVATIONS

The authors describe the case of a 76-year-old woman with refractory cluster-tic syndrome who underwent GKRS with double target (the retrogasserian portion of the trigeminal nerve and the sphenopalatine ganglion). The Numerical Rating Scale (NRS) of pain and the Barrow Neurological Institute (BNI) pain intensity score before treatment were 7 (up to 10 during paroxysmal pain attacks) and V, respectively. At last follow-up, 24 months after GKRS, the patient had discontinued her pain medications and NRS and BNI pain scores were 1 and I, respectively. No trigeminal sensory disorders were reported.

LESSONS

The present case shows that GKRS, in selected cases, could be an effective treatment in patients with refractory cluster-tic syndrome.

Factors affecting long-lasting pain relief after Gamma Knife radiosurgery for trigeminal neuralgia: a single institutional analysis and literature review

Gamma Knife radiosurgery (GKRS) is a well-established safe and effective treatment for trigeminal neuralgia (TN) with high initial success rate (80-90%). Why the pain relief is progressively decreased with time is a matter of considerable debate. To investigate factors related to long-lasting pain relief, the authors conducted a retrospective analysis focusing on anatomical and radiosurgical related parameters, chosen according to literature review. One hundred and twelve patients with classical trigeminal neuralgia and follow-up longer than 12 months were selected from our institutional consecutive series of patients treated by GKRS. Patients were followed for a mean period of 61.5 ± 3.5 months (range, 12-126 months) to evaluate, as endpoints, long-term pain relief and hypoesthesia onset. The median maximum radiation dose was 80 Gy (range 70-90 Gy). Factors related to poor long-term pain relief were prescription dose < 80 Gy (p = 0.038), calibration dose rate < 2.5 Gy/min (p = 0.018), and distance between isocenter and trigeminal nerve emergence > 8 mm (p < 0.001). When analyzing patients who received 80 Gy as maximum dose without any sector blocking, we notice that ID₅₀ < 2.7 mJ was predictive for longer period of pain control (p = 0.043). It was experienced also among patients in which a small volume of the nerve (< 35%) received more than 80% of the maximal dose, compared to those in which a larger volume of the nerve was irradiated with maximal dose (p 0.034). This last result was significant if the shot was 8 mm or less from the pons. Several single-patient anatomical and radiosurgical parameters should be considered to improve GKRS effectiveness.

Impact of molecular subtype on 1325 early-stage breast cancer patients homogeneously treated with hypofractionated radiotherapy without boost: Should the indications for radiotherapy be more personalized?

Aim

We report molecular subtype impact on 1325 early breast cancer (BCa) patients treated with whole breast hypofractionated (WBH) adjuvant forward-planned intensity modulated radiotherapy (F-IMRT) without boost.

Methods and materials

From 02/2009-05/2017 1325 patients with pTis-pT3, pNx-N1aM0 BCa who underwent breast conservation surgery were treated with WBHF-IMRT in our institute, to a total dose of 40 Gy/15 fractions, without boost. Median age: 62 (interquartile range-IQR-:51.14–70.53) years. Histology: 8% in situ carcinoma (ISC), 92% invasive tumors. Molecular subtypes (invasive tumors): 49.9% Luminal A, 33.1% Luminal B Her2 negative (−), 6.2% Luminal B Her2 positive (+), 3.6% Hormone Receptor (HR)- Her2+, 7.1% Triple negative (TNBC), and 0.2% HR+. Chemotherapy (CT) was prescribed in 28% of patients, hormonal therapy in 80.3%, monoclonal antibodies (MAb) in 86.8% of Luminal B Her2+ and 97.7% of HR- Her2+ patients.

Results

Median follow up was 72.43 (IQR: 44.63–104.13) months. The 5-year Kaplan-Meier estimates of local relapse-free survival (LRFS) was 97.8%, regional-(RRFS) 98.6%, loco-regional- (LRRFS) 96.9%, distant- (DRFS) 96.6%, disease-free survival (DFS) 94.8% and overall survival (OS) 95.5%. Considering molecular subtypes, 5-year LRFS was: 99.8% for Luminal A, 96.7% for Luminal B Her2-, 94.1% for Luminal B Her2+, 87.9% for HR- Her2+, 95.1% for TNBC and 99.1% for in situ carcinoma.

Conclusion

While the overall estimated probability of LR within 5 years after WBHF-IMRT without boost is good (2.2%), molecular subtypes have a strong impact, despite MAb therapy in Her2+ patients, and CT for TNBC patients, and could be used as a parameter in deciding the boost prescription.

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Hypofractionated three-weeks radiotherapy ensures good local control whitout boost.

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In 1325 early stage breast cancers 5-year local relapse without boost was 2.2%.

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Molecular subtypes have a strong impact on estimated probability of local relapse.

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5-year local control (LC) was 99.8% for Luminal A vs 87.9% for HR- Her2+.

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5-year LC was 96.7% for Luminal B Her2-, 94.1% for Luminal B Her2+, 95.1% for TNBC.

Italian inter-society expert panel position on radiological exposure in Neonatal Intensive Care Units

BACKGROUND

In the recent years, clinical progress and better medical assistance for pregnant women, together with the introduction of new complex technologies, has improved the survival of preterm infants. However, this result requires frequent radiological investigations mostly represented by thoracic and abdominal radiographs in incubators. This document was elaborated by an expert panel Italian inter-society working group (Radiologists, Paediatricians, Medical Physicists) with the aim to assist healthcare practitioners in taking choices involving radiation exposures of new-born infants and to provide practical recommendations about justification and optimization in Neonatal Intensive Care Units. The adherence to these practice recommendations could ensure a high quality and patient safety. More complex and less common radiological practice, such as CT scan or fluoroscopy have been excluded.

METHODS

The consensus was reached starting from current good practice evidence shared by four scientific societies panel: AIFM (Italian Association of Physics in Medicine), SIN (Italian Neonatology Society), SIP (Italian Paediatric Society), SIRM (Italian Medical Radiology Society) in order to guarantee good standard practices for every professional involved in Neonatal Intensive Care Units (NICU). The report is divided into clinical and physical-dosimetric sections: clinical Indications, good practice in radiological exposures, devices, exposure parameters and modalities, patient positioning and immobilization, Reference Diagnostic Levels, operators and patient's radiation protection. Another important topic was the evaluation of the different incubators in order to understand if the consequences of the technological evolution have had an impact on the increase of the dose to the small patients, and how to choose the best device in terms of radiation protection. At the end the working group faced the problem of setting up the correct communication between clinicians and parents following the most recent indications of the international paediatric societies.

RESULTS

Taking into account the experience and expertise of 10 Italian Centres, the guideline sets out the criteria to ensure a high standard of neonatal care in NICU about procedures, facilities, recommended equipment, quality assurance, radiation protection measures for children and staff members and communication on radiation risk.

CONCLUSIONS

This document will allow a standardization of the approach to the exposures in NICU, although oriented to a flexible methodology.

Clinical Implementation of Knowledge-Based Automatic Plan Optimization for Helical Tomotherapy

PURPOSE

To implement knowledge-based (KB) automatic planning for helical TomoTherapy (HTT). The focus of the first clinical implementation was the case of high-risk prostate cancer, including pelvic node irradiation.

METHODS AND MATERIALS

One hundred two HTT clinical plans were selected to train a KB model using the RapidPlan tool incorporated in the Eclipse system (v13.6, Varian Inc). The individually optimized KB-based templates were converted into HTT-like templates and sent automatically to the HTT treatment planning system through scripting. The full dose calculation was set after 300 iterations without any additional planner intervention. Internal (20 patients in the training cohort) and external (28 new patients) validation were performed to assess the performance of the model: Automatic HTT plans (KB-TP) were compared against the original plans (TP) in terms of organs at risk and planning target volume (PTV) dose-volume parameters and by blinded clinical evaluation of 3 expert clinicians.

RESULTS

KB-TP plans were generally better than or equivalent to TP plans in both validation cohorts. A significant improvement in PTVs and rectum-PTV overlap dosimetry parameters were observed for both sets. Organ-at-risk sparing for KB-TP was slightly improved, which was more evident in the external validation group and for bladder and bowel. Clinical evaluation reported KB-TP to be better in 60% of cases and worse in 10% compared with TP (P < .05).

CONCLUSIONS

The fully KB-based automatic planning workflow was successfully implemented for HTT planning optimization in the case of high-risk patients with prostate cancer.

Residual intra-fraction error in robotic spinal stereotactic body radiotherapy without immobilization devices

BACKGROUND AND PURPOSE

Spinal stereotactic body radiotherapy (SBRT) involves large dose gradients and high geometrical accuracy is therefore required. The aim of this work was to assess residual intra-fraction error with a tracking robotic system for non-immobilized patients. Shifts from the first alignment (i.e. mimicking the unavailability of tracking) were also quantified.

MATERIALS AND METHODS

Forty-two patients treated for spinal metastasis (128 fractions, 4220 images) were analyzed. Residual error was quantified as the difference between translations/rotations referring to consecutive x-ray images during delivery (tracking) and to the initial set-up (no-tracking). The error distribution for each fraction/patient and the entire population was assessed for each axis/rotation angle. The impact of lesion sites, fractionation and patient's pain (VAS score) were investigated. Finally, the dosimetric impact of residual motion was quantified in the four most affected fractions.

RESULTS

Mean overall errors (OE) were near 0 (SD < 0.1 mm). Residual translations/rotations >1 mm/1° were found in less than 1.5%/1% of measurements. Lesion site and fractionation showed no impact. The dosimetric impact in the most affected fractions was negligible. For "no-tracking", mean OE was <1 mm/0.5°; less than 2% of displacements were >2 mm/1° within 10 min from the start of treatment with an increasing probability of shifts >2 mm over time. A significantly higher fraction of OE ≥ 2 mm was found for patients with pain in case of no-tracking.

CONCLUSIONS

Spine tracking with a latest-generation robotic system is highly efficient for non-immobilized patients: residual error is time independent and close to 0. For delivery times >7-8 min, tracking should be considered as mandatory for non-immobilized patients.

Virtual Tangential-fields Arc Therapy (ViTAT) for whole breast irradiation: Technique optimization and validation

PURPOSE

To test the performances of a volumetric arc technique named ViTAT (Virtual Tangential-fields Arc Therapy) mimicking tangential field irradiation for whole breast radiotherapy.

METHODS

ViTAT plans consisted in 4 arcs whose starting/ending position were established based on gantry angle distribution of clinical plans for right and left-breast. The arcs were completely blocked excluding the first and last 20°. Different virtual bolus densities and thicknesses were preliminarily evaluated to obtain the best plan performances. For 40 patients with tumor laterality equally divided between right and left sides, ViTAT plans were optimized considering the clinical DVHs for OARs (resulting from tangential field manual planning) to constrain them: ViTAT plans were compared with the clinical tangential-fields in terms of DVH parameters for both PTV and OARs.

RESULTS

Distal angle values were suggested in the ranges [220°,240°] for the right-breast and [115°,135°] for the left-breast cases; medial angles were [60°,40°] for the right side and [295°,315°] for the left side, limiting the risk of collision. The optimal virtual bolus had -500 HU density and 1.5 cm thickness. ViTAT plans generated dose distributions very similar to the tangential-field plans, with significantly improved PTV homogeneity. The mean doses of ipsilateral OARs were comparable between the two techniques with minor increase of the low-dose spread in the range 2-15 Gy (few % volume); contralateral OARs were slightly better spared with ViTAT.

CONCLUSION

ViTAT dose distributions were similar to tangential-fields. ViTAT should allow automatic plan optimization by developing knowledge-based DVH prediction models of patients treated with tangential-fields.

Cumulative intracranial tumour volume prognostic assessment: a new predicting score index for patients with brain metastases treated by stereotactic radiosurgery

Brain metastases (BM) represent the most common intracranial malignancy in adults. Limitations of existing prognostic models reduce their predictivity and clinical applicability. The aim of this study is to validate the cumulative intracranial tumour volume prognostic assessment (CITVPA) as a new prognostic score system for patients with BM treated by Stereotactic Radiosurgery (SRS). Between January 2001 and December 2015, 1894 patients underwent Gamma Knife SRS treatment. The CITVPA model was implemented and validated as follows: the CITV cut-offs were identified thanks to a receiver-operating characteristic (ROC) curve analysis; the survival predictive factors were selected through a Cox proportional hazard model; its prognostic power was compared to RPA, SIR and GPA through the Harrel concordance index (HCI). According to the ROC curve analysis, the CITV cut-off values were set at 1.5 and 4.0 cc. Based on the multivariate analysis, the CITVPA model included: age (OR 1.010, 95% CI 1.005-1.015, p < 0.001), KPS (OR 0.960, 95% CI 0.956-0.965, p < 0.001), extracranial metastases (OR 1.287, 95% CI 1.154-1.437, p < 0.001), BM number (OR 1.193, 95% CI 1.047-1.360, p = 0.008), and CITV (OR 1.028, 95% CI 1.020-1.036, p < 0.001). A score between 0 and 1 was attributed to each prognosticator; a global CITVPA score ranging from 0 to 5 was assigned with higher results corresponding to worse outcomes. The CITVPA (HCI = 0.64) exhibited a significantly (p < 0.001) higher prognostic power compared to RPA (HCI = 0.55), SIR (HCI = 0.55) and GPA (HCI = 0.61). The CITVPA represents a reliable prognostic system for patients with BM treated by SRS. However, further prospective and multicentric studies are necessary before its applicability in clinical practice.

Gamma Knife Radiosurgery for Trigeminal Neuralgia: Role of Trigeminal Length and Pontotrigeminal Angle on Target Definition and on Clinical Effects

OBJECTIVE

Gamma Knife radiosurgery (GKRS) is a well-defined treatment for trigeminal neuralgia. The aim of this study was to determine how the GKRS planning might change on the basis of the patient's own anatomy and how to best choose the target location.

METHODS

Trigeminal cisternal length, pontotrigeminal angle, and distance between middle of the shot and emergence were evaluated in 112 consecutive GKRS plans for trigeminal neuralgia. Correlations with pain outcomes and facial hypoesthesia were analyzed.

RESULTS

The mean angle was 29° ± 4.4° and 37° ± 0.9°, respectively, in patients developing and not developing severe hypoesthesia (P = 0.045), despite no significant difference on brainstem dose (11.9 ± 0.8 and 10.5 ± 0.3 Gy; P = 0.22). The length of the nerve was not relevant on clinical outcomes but the shot-emergence distance (mean 8.1 ± 0.2 mm) depended on both trigeminal length and angle (P = 0.01). At constant prescription dose, 6-month cumulative rates of pain relief and control without therapy were 52.9% when the shot-emergence distance was ≤8 mm, whereas 25% when this distance was >8 mm (P = 0.017). The maintenance of good pain control was more long lasting in the first group (49.5 ± 6.6 vs. 25.4 ± 5 months; P = 0.006) with a 5-year cumulative rate of 70% and 26%, respectively (P < 0.001).

CONCLUSIONS

The pontotrigeminal angle and the shot-emergence distance should be considered during GKRS planning: the first as a potential risk factor for hypoesthesia, and the second should not exceed 8 mm.

Safety and efficacy of multisession gamma knife radiosurgery for residual or recurrent pituitary adenomas

PURPOSE

To define the efficacy and complications of multisession Gamma Knife radiosurgery (MGKRS) delivered in three consecutive sessions for the treatment of residual or recurrent pituitary adenomas (PAs).

METHODS

This was a retrospective study of data from the Neurosurgery and Gamma Knife Radiosurgery Department at San Raffaele Hospital between May 2008 and September 2017. We recruited 47 consecutive patients undergoing MGKRS in three consecutive fractions for residual or recurrent PA with a distance from the anterior optic pathway inferior to 2-3 mm.

RESULTS

Thirty-eight (80.8%) patients had a nonfunctioning-PA (NFPA) while 9 (19.2%) had a hormone-secreting PA (HSPA). Tumor control was achieved in 100% of patients. Tumor shrinkage was seen in 33 out of 44 (75.0%) patients with a radiological follow-up. Mean tumor volume before MGKRS was 3.93 cm³. The mean tumor volume at last follow-up was 2.11 cm³, with a mean tumor shrinkage of 50.2%, as compared with baseline. One case of suspected radiation-induced optic neuropathy (RION) was documented while new-onset hypopituitarism for any axis occurred in 12 of the 31 (38.7%) patients at risk. The mean follow-up was 44.6 ± 4.0 months (range, 6-111 months).

CONCLUSIONS

MGKRS is a valid alternative to external fractionated radiotherapy and other types of stereotactic radiosurgery for the treatment of PAs, achieving a high tumor control rate with a low risk of visual deterioration. Moreover, the majority of patients showed a significant reduction of tumor size in the long term.

Bone resorption in autologous cryopreserved cranioplasty: quantitative evaluation, semiquantitative score and clinical significance

BACKGROUND

Changes after reimplantation of the autologous bone have been largely described. However, the rate and the extent of resorption in cranial grafts have not been clearly defined. Aim of our study is to evaluate the bone flap resorption (BFR) after cryopreservation.

METHODS

We retrospectively reviewed 27 patients, aged 18 years or older, subjected to cranioplasty (CP) adopting autologous cryopreserved flap. The BFR was derived from the percentage of decrease in flap volume (BFR%), comparing the first post-operative computed tomography (CT) and the last one available (performed at least 1 year after surgery). We also proposed a semiquantitative scoring system, based on CT, to define a clinically workable BFR classification.

RESULTS

After a mean ± SE follow-up of 32.5 ± 2.4 months, the bone flap volume decreased significantly (p < 0.0001). The mean BFR% was 31.7 ± 3.8% and correlated with CT-score (p < 0.001). Three BFR classes were described: mild (14.8% of cases) consisting in minimal bone remodelling, CT-score ≤ 6, mean BFR% = 3.5 ± 0.7%; moderate (51.9% of cases) corresponding to satisfactory cerebral protection, CT-score < 13, mean BFR% = 25.6 ± 2.2%; severe (33.3% of cases) consisting in loss of cerebral protection, CT-score ≥ 13, mean BFR% = 54.2 ± 3.9%. Females had higher BFR% than males (p = 0.022). BFR classes and new reconstructive surgery were not related (p = 0.58).

CONCLUSIONS

BFR was moderate or severe in 85.2% of re-implanted cryopreserved flaps. The proposed CT-score is an easy and reproducible tool to define resorption extent.

Radiosurgical treatment of arteriovenous malformations in a retrospective study group of 33 children: the importance of radiobiological scores

PURPOSE

Arteriovenous malformations' (AVMs) obliteration depends on several factors; among the many factors that must be considered to obtain a high rate of obliteration and a low rate of complications, Flickinger-Pollock Score (FPS) seems to have an important role but still have to be validated in the pediatric population while Paddick-Conformity Index (PCI) still has no demonstration of its utility on the outcome and is considered only as a treatment quality marker.

METHODS

We retrospectively analyzed 33 consecutive children (2-18 years) with an AVM, treated with stereotactic radiosurgery Gamma Knife (SRS-GK) from 2001 to 2014 in our institution. We assess angiographic (DSA) Obliteration Rate (OR) as well FPS and PCI to draw conclusions.

RESULTS

DSA-OR was 60.6% with a rate of hemorrhage of 0%. median target volume (TV) was 3.60 cc (mean 4.32 ± 3.63; range 0.15-14.2), median PD was 22 Gy (mean 21.4 ± 2.6; range 16.5-25). Median percentage of coverage was 98% (mean 97 ± 3; range 84-100). The median modified FPS was 0.78 (mean 0.89 ± 0.52; range 0.21-2.1) and highly correlate with OR (p = 0.01). The median PCI was 0.65 (mean 0.65 ± 0.14; range 0.34-0.95) A PCI lower than 0.57 highly correlates with final OR (p = 0.02).

CONCLUSION

SRS-GK was safe and gradually effective in children. A prescription dose-like that used in adult population (i.e. > 18 and between 20 and 25 Gy) is essential to achieve obliteration. A PD of 23 Gy and 22 Gy did impact OR, respectively (p = 0.02) and (p = 0.05). FPS and PCI are valuable scores that seem to correlate with the OR also in the pediatric population although further prospective studies are needed to confirm these observations.

Gamma Knife radiosurgery for glomus tumors: Long-term results in a series of 30 patients

BACKGROUND

Glomus tumors are rare and benign hypervascular tumors. Surgery represented the mainstay of their treatment, even if it has been associated with high morbidity and mortality rates. Recently, the treatment shifted to a multimodal approach and Gamma Knife radiosurgery represents one of the treatment options.

METHODS

Authors retrospectively analyzed the clinical and radiological outcome of a series of patients who underwent Gamma Knife radiosurgery for glomus tumors.

RESULTS

Thirty patients underwent Gamma Knife radiosurgery. Mean tumor volume was 7.69 cc (range 0.36-24.6). Mean tumor margin dose was 16 Gy (range 13-18). Median follow-up was of 91 months (mean 90; range 11-172). Overall clinical control rate was 100%; overall volumetric tumor control rate was 96.6%. Patients' and tumors' characteristics, treatment data, and outcome have been analyzed.

CONCLUSION

Gamma Knife radiosurgery represents a safe and effective treatment for glomus tumors. Longer follow-up and larger cohort studies are needed to definitively outline the role of Gamma Knife radiosurgery for glomus tumors.

Single fraction and multisession Gamma Knife radiosurgery for craniopharyngioma

PURPOSE

The optimal management of residual or recurring craniopharyngioma is still a matter of debate even though adjuvant radiation therapy plays a crucial role. Aim of our study is to report the results of single fraction or multisession Gamma Knife radiosurgery (GKRS) in patients with craniopharyngioma.

METHODS

We included 50 consecutive patients treated from 1994 to 2016. All patients had at least one post GKRS magnetic resonance imaging reviewed at our center. Vital status of all patients was assessed at the end of 2016.

RESULTS

There were 29 males (58.0%) and 21 females (42.0%). Mean age was 41.5 ± 2.8 year. Single session GKRS was delivered in 29 patients (58.0%). The mean tumor volume was 2.15 ± 0.3 cm³ and the mean prescription dose to the tumor margin was 14.3 ± 0.3 Gy. During a mean follow-up of 74.6 ± 8.4 months, seven patients (14.0%) had recurrence of disease. The 5- and 10-year recurrence-free survivals were 90.3% (95% CI, 81.0-99.6%) and 78.4% (95% CI, 59.9-96.9%), respectively. Multisession GKRS was not less effective than single fraction GKRS. Eighteen of the 28 patients (64.3%) had a tumor volume decrease of at least 10%. No serious side effects occurred after GKRS treatment, except for one case of mild visual worsening.

CONCLUSIONS

GKRS was effective for controlling the growth of residual or recurrent craniopharyngioma. Serious side effects were uncommon. Multisession GKRS seems a very promising tool to allow performing GKRS even in patients with large residual or recurrent craniopharyngioma.

Results of volume-staged fractionated Gamma Knife radiosurgery for large complex arteriovenous malformations: obliteration rates and clinical outcomes of an evolving treatment paradigm

OBJECTIVE There are few reported series regarding volume-staged Gamma Knife radiosurgery (GKRS) for the treatment of large, complex, cerebral arteriovenous malformations (AVMs). The object of this study was to report the results of using volume-staged Gamma Knife radiosurgery for patients affected by large and complex AVMs. METHODS Data from 20 patients with large AVMs were prospectively included in the authors' AVM database between 2004 and 2012. A staging strategy was used when treating lesion volumes larger than 10 cm³. Hemorrhage and seizures were the presenting clinical feature for 6 (30%) and 8 (40%) patients, respectively. The median AVM volume was 15.9 cm³ (range 10.1-34.3 cm³). The mean interval between stages (± standard deviation) was 15 months (± 9 months). The median margin dose for each stage was 20 Gy (range 18-25 Gy). RESULTS Obliteration was confirmed in 8 (42%) patients after a mean follow-up of 45 months (range 19-87 months). A significant reduction (> 75%) of the original nidal volume was achieved in 4 (20%) patients. Engel Class I-II seizure status was reported by 75% of patients presenting with seizures (50% Engel Class I and 25% Engel Class II) after radiosurgery. After radiosurgery, 71.5% (5/7) of patients who had presented with a worsening neurological deficit reported a complete resolution or amelioration. None of the patients who presented acutely because of hemorrhage experienced a new bleeding episode during follow-up. One (5%) patient developed radionecrosis that caused sensorimotor hemisyndrome. Two (10%) patients sustained a bleeding episode after GKRS, although only 1 (5%) was symptomatic. High nidal flow rate and a time interval between stages of less than 11.7 months were factors significantly associated with AVM obliteration (p = 0.021 and p = 0.041, respectively). Patient age younger than 44 years was significantly associated with a greater than 75% reduction in AVM volume but not with AVM obliteration (p = 0.024). CONCLUSIONS According to the results of this study, volume-staged GKRS is an effective and safe treatment strategy for large, complex, cerebral AVMs for which microsurgery or endovascular approaches could carry substantially higher risks to the patient. Radiation doses up to 20 Gy can be safely administered. The time interval between stages should be shorter than 11.7 months to increase the chance of obliteration. High nidal flow and a patient age younger than 44 years were factors associated with nidus obliteration and significant nidus reduction, respectively.

PET Evaluation of Late Cerebral Effect in Advanced Radiation Therapy Techniques for Cranial Base Tumors

BACKGROUND AND OBJECTIVE

Even though the benefits of radiation therapy are well established, it is important to recognize the broad spectrum of radiation-induced changes, particularly in the central nervous system. The possible damage to the brain parenchyma may have clinical consequences and in particular cognitive impairment might be one of the major complications of radiotherapy. To date, no studies have investigated the effects of focal radiation therapy on brain structure and function together with the assessment of their clinical outcomes at a long follow-up.

METHODS

In this prospective study, we evaluated in six patients the possible brain late effects after radiation therapy, using a standardized neuropsychological battery, MRI and 18F-FDG PET using SPM and semi-quantitative methods, in patients affected by cranial base tumors who underwent gamma knife or tomotherapy.

RESULTS

Neuropsychological examinations showed no cognitive impairment after the treatment. In all patients, both MRI assessment and 18F-FDG-PET did not reveal any local or distant anatomical and metabolic late effects.

CONCLUSION

The present study support the safety of advanced radiation therapy techniques. 18F-FDGPET, using SPM and semi-quantitative methods, might be a valuable tool to evaluate the cerebral radiotoxicity in patients treated for brain neoplasms.

Laparoscopic appendectomy for the treatment of acute appendicitis: A single center experience

AIM

The aim of our study is to compare the pre, intra- and post-operative variables of the two surgical techniques, to demonstrate if laparoscopic appendectomy can be considered safer and associated to better outcome.

MATERIAL OF STUDY

A retrospective analysis of 175 patients has been carried out. Alvarado score, time of surgery, analgesic therapy and length of hospital stay calculated. Finally, postoperative complications were recorded.

RESULTS

From January 2011 - April 2016 175 patients were enrolled: 128pts underwent laparoscopic technique and 47pts open technique. The average value of Alvarado score is lower in LA group than in OA group just as the average time of surgery and the use of post-operative analgesic therapy.

DISCUSSION

LA has become the surgical technique mostly performed for the treatment of simple and complicated acute appendicitis. Our study shows that LA pts are younger with a statistically significant difference CONCLUSIONS: Most of the emergency appendectomies were performed via laparoscopic technique, especially in young patients. Laparoscopy is safer and associated to better outcome.

KEY WORDS

Alvarado Score, Laparoscopic appendectomy, Open appendectomy.

Effectiveness of Gamma Knife Radiosurgery in Improving Psychophysical Performance and Patient's Quality of Life in Idiopathic Trigeminal Neuralgia

OBJECTIVE

To assess effectiveness of Gamma Knife Radiosurgery (GKRS) in improving quality of life (QoL) in patients with idiopathic trigeminal neuralgia (TN).

METHODS

Between January 2001 and October 2013, 166 patients with medically resistant TN were treated at our institution with GKRS. Patients were divided into 2 groups: patients with typical TN (TTN) and patients with atypical TN (ATN). All patients underwent clinical evaluation using Marseille and Barrow Neurological Institute pain and numbness scales; in addition, they completed the Short-Form 36 Health Survey, Activities of Daily Living, and Excellent Good Fair Poor questionnaires and underwent psychological and neurologic examination.

RESULTS

Mean follow-up time was 64.7 months. All Short-Form 36 domains were significantly improved in both groups after treatment, with an evident trend to reach the median values of healthy Italian population. Mean postoperative Activities of Daily Living score in the TTN group and ATN group were 5.8 and 5.4, respectively, and Karnofsky Performance Status increased to 94.2 and 86.4, respectively. Pain recurrence negatively affected patients' QoL and psychofunctional performance without reaching statistical significance. At the last follow-up, 73% of patients were clustered in the pain-relief group.

CONCLUSIONS

GKRS significantly improves QoL and functional and psychosocial performance of patients with idiopathic trigeminal neuralgia. A trend was observed toward a more favorable outcome in patients with TTN, compared with patients with ATN, without reaching a statistically significant distinction.

Frequency, pattern, and outcome of recurrences after gamma knife radiosurgery for pituitary adenomas

Gamma Knife radiosurgery is often used in pituitary adenomas. Aim of our study is to describe the characteristics and long-term outcome of patients with adenoma recurrence after Gamma Knife radiosurgery. We conducted a retrospective analysis of patients with pituitary adenoma treated by Gamma Knife radiosurgery between 1994 and 2014. Tumor recurrence was labeled as "in field" when the tumor growth occurred adjacent or within the prescribed isodose, whereas it was classified as "out of field" when the tumor growth occurred outside the prescribed isodose. Five hundred forty-three patients were included, 272 (50.1 %) had a nonfunctioning pituitary adenoma (NFPA) and 271 (49.9 %) patients had a hormone secreting-pituitary adenoma. The median follow-up after GKRS was 78 months (IQR, 36-125 months). Thirty-nine patients (7.2 %) had recurrence of disease and it was more frequent in patients with NFPA than in patients with hormone secreting adenomas (9.6 % vs. 4.8 %). The 10-yr progression-free survival in patients with NFPA was 78.7 % (95 % CI 69.5 - 87.9 %), as compared with 93.3 % (95 % CI 89.3 - 97.3 %; p < 0.01) in hormone secreting adenomas. Tumor recurrence was "in field" in 17 cases (43.6 %) and "out of field" in 22 cases (56.4 %). Seven of the 39 patients with recurrence died despite further treatments. Six of these patients had an "in field" recurrence. Recurrence of a pituitary adenoma after GKRS may occur several years after initial treatment. Distinction between "in field" and "out of field" tumor recurrence probably reflects two different pathophysiological mechanisms and may have prognostic importance.

Gamma Knife Radiosurgery for Low-Grade Gliomas: Clinical Results at Long-Term Follow-Up of Tumor Control and Patients' Quality of Life

OBJECTIVE

First-line therapy for low-grade gliomas (LGGs) is surgery, in some cases followed by radiotherapy and chemotherapy. Gamma Knife radiosurgery (GKRS) has gained more relevance in the management of these tumors. The aim of this study was to assess efficacy and safety of GKRS for treatment of LGGs.

METHODS

Between 2001 and 2014, 42 treatments were performed on 39 patients harboring LGGs; 48% of patients underwent previous surgery, and 20.5% underwent previous radiotherapy. Mean tumor volume was 2.7 cm³, and median margin dose was 15 Gy.

RESULTS

Mean follow-up was 60.5 months (range, 6-164 months). Actuarial progression-free survival was 74.9%, 52.8%, and 39.1% at 1 year, 5 years, and 10 years; actuarial overall survival was 97.4%, 94.6%, and 91.8% at 9 months, 1 year, and 5 years. Solid tumor control was achieved in 69.2% of patients, whereas cystic enlargement was recorded in 12.9% of cases. At last follow-up, volume reduction was recorded in 57.7% of cases, and median volume decreased by 33.3%. Clinical improvement was observed in 52.4% of patients. Karnofsky performance scale score was improved in 15 patients (45.5%), unchanged in 17 patients (51.5%), and worsened in 1 patient (3%). Mean posttreatment scores of 36-item short form health survey domains did not significantly differ from scores in a healthy Italian population.

CONCLUSIONS

This study confirms safety and effectiveness of GKRS for LGGs in controlling tumor growth, relevantly improving patients' overall and progression-free survival. GKRS improved patients' functional performance and quality of life, optimizing social functioning and minimizing disease-related psychological impact.

Evaluation of the peripheral dose in stereotactic radiotherapy and radiosurgery treatments

PURPOSE

The main purpose of this work was to compare peripheral doses absorbed during stereotactic treatment of a brain lesion delivered using different devices. These data were used to estimate the risk of stochastic effects.

METHODS

Treatment plans were created for an anthropomorphic phantom and delivered using a LINAC with stereotactic cones and a multileaf collimator, a CyberKnife system (before and after a supplemental shielding was applied), a TomoTherapy system, and a Gamma Knife unit. For each treatment, 5 Gy were prescribed to the target. Measurements were performed with thermoluminescent dosimeters inserted roughly in the position of the thyroid, sternum, upper lung, lower lung, and gonads.

RESULTS

Mean doses ranged from of 4.1 (Gamma Knife) to 62.8 mGy (LINAC with cones) in the thyroid, from 2.3 (TomoTherapy) to 30 mGy (preshielding CyberKnife) in the sternum, from 1.7 (TomoTherapy) to 20 mGy (preshielding CyberKnife) in the upper part of the lungs, from 0.98 (Gamma Knife) to 15 mGy (preshielding CyberKnife) in the lower part of the lungs, and between 0.3 (Gamma Knife) and 10 mGy (preshielding CyberKnife) in the gonads.

CONCLUSIONS

The peripheral dose absorbed in the sites of interest with a 5 Gy fraction is low. Although the risk of adverse side effects calculated for 20 Gy delivered in 5 Gy fractions is negligible, in the interest of optimum patient radioprotection, further studies are needed to determine the weight of each contributor to the peripheral dose.