Search

Purpose This paper analyzes Tomotherapy-based intracranial stereotactic radiosurgery (HTSRS) of brain metastasis targeting two end-points: 1) evaluation of dose homogeneity, conformity and gradient scores for single and multiple lesions and 2) assay of dosimetric criticality of completion of HTSRS procedures. Methods 42 treatment plans of 33 patients (53 brain lesions) treated with HTSRS were analyzed. Dose to healthy brain, homogeneity, conformity and gradient indexes were evaluated for each lesion. Influence of Field Length and multiple lesions cross-talk effect were assessed. Treatment interruption and completion was investigated using radiochromic films in order to examine the delivered dose and its robustness to patient intrafraction movement. Results The average dose homogeneity index was 1.04 ± 0.02 (SD). Average dose conformity and gradient score indexes were 1.4 ± 0.2 and 50 ± 14 respectively. We found a strong correlation of the dose to healthy brain and conformity and gradient indexes with target(s) volume for which analytical functions were obtained. Field Length and cross-talk effect were significantly correlated with poor gradient scores, but were found not to affect dose conformity. Conclusions Homogeneity and conformity of HTSRS plans achieved excellent scores, while dose falloff and dose to healthy brain were slightly larger when compared with non-coplanar SRS techniques. Care should be given if treating large (>3 cc) or multiple near in-plane lesions in order to reduce dose to healthy brain. Analysis of interrupted treatments suggests splitting HTSRS treatments in two consecutive fractions in order to prevent target miss and overdosage due to patient intrafraction movement. [ABSTRACT FROM AUTHOR]

The present work evaluates the per-procedure, annual collective and per-capita effective doses to the Aosta Valley region population from nuclear medicine (NM) examinations performed from 2005 to 2011 at the regional NM department. Based on its demographical and socioeconomics characteristics, this area can be considered as representative of the level I countries, as defined by the United Nations Scientific Committee on the Effects of Atomic Radiation. The NM per-procedures effective doses were within the range of 0.018–35 mSv. A steady frequency per 10 000 inhabitants has been observed, together with a decrease for thyroid and whole-body bone scintigraphy. Myocardial and bone scintigraphy studies were the major contributors to the total collective effective dose. The mean annual collective and per-capita effective doses to the population were 15 man Sv y−1 and 120 µSv y−1, respectively. The NM contribution to the total per-capita effective dose accounts for 5.9 % of that due to the medical ionising radiation examinations overall. [ABSTRACT FROM AUTHOR]

Objectif de l’étude Nous présentons l’analyse rétrospective d’une cohorte de patients atteints d’un cancer du rectum localement évolué pris en charge par chimioradiothérapie délivrée avec la tomothérapie hélicoïdale, par une technique de simultaneous integrated boost (SIB) et un contrôle quotidien de la position du patient, suivie par une chirurgie. Matériel et méthode Quatre-vingt-six patients ont reçu 45 Gy (1,8 Gy par fraction) au niveau du rectum, du mésorectum et des ganglions de drainage pelviens (présacrés, iliaques internes et obturateurs jusqu’à L5-S1), délivrés avec un SIB jusqu’à la dose totale de 50 Gy (2 Gy par fraction) dans le volume tumoral macroscopique (GTV) rectal et ganglionnaire, et avec une chimiothérapie concomitante (capécitabine, 825 mg/m2, deux fois par jour). La marge entre les volumes cibles anatomoclinique et prévisionnel (CTV-PTV) a été de 5 mm pour les deux volumes. Tous les patients ont été opérés après la chimioradiothérapie (résection R0 : 84/86 patients). Quarante-cinq patients ont reçu une chimiothérapie adjuvante. Le degré de régression tumorale (TRG) a été évalué avec le score de Mandard. Résultats Le temps de suivi médian était de 54 mois (extrêmes : 4–91 mois). Trois et six patients ont souffert, respectivement, d’une toxicité de grade 3 ou plus aiguë ou tardive. Vingt et un pour cent et 30 % des patients étaient, respectivement, en situation de réponse pathologique complète (TRG = 1) ou quasi complète. Les taux de contrôle local, de survie globale, et de survie sans rechute à 5 ans étaient, respectivement, de 78 %, 84 % et 66 %. Les patients avec un TRG 1–2 avaient des meilleurs taux de contrôle local (94 % contre 78 %, p = 0,01) et de survie globale (94 % contre 33 %, p < 0,001). Conclusion Un SIB délivré avec une tomothérapie et un contrôle quotidien de la position du patient est bien toléré et efficace. Un TRG 1–2 après la chimioradiothérapie est un facteur pronostique de contrôle local et de survie globale. [ABSTRACT FROM AUTHOR]

Objectif de l’étude La radiothérapie stéréotaxique d’ablation est une technique émergente dans la prise en charge des tachycardies ventriculaires réfractaires aux traitements médicamenteux et à l’ablation par cathéter. Nous rapportons ici les résultats des premiers patients traités dans notre centre. Matériel et méthode Les patients inclus souffraient de tachycardies ventriculaires ou d’une tempête rythmique réfractaires aux traitements classiques. Avant chaque traitement, afin de localiser le substrat de la tachycardie ventriculaire, une cartographie tridimensionnelle a été réalisée durant une exploration électrophysiologique endocavitaire. Pour chaque patient, le cardiologue a délimité le substrat de la tachycardie ventriculaire sur la scanographie de radiothérapie grâce aux informations de la cartographie. L’électrode de défibrillation du défibrillateur automatique implantable a servi de fiduciel pour assurer le suivi en temps réel (tracking). Une dose de 25 Gy a été délivrée sur le substrat de la tachycardie ventriculaire grâce à un accélérateur linéaire robotisé Cyberknife® M6. Résultats Depuis septembre 2017, trois patients ont été pris en charge : deux patients électifs et un patient hospitalisé en réanimation en raison d’une tempête rythmique à l’origine de nombreux chocs électriques délivrés par le défibrillateur automatique implantable, et nécessitant une anesthésie générale. Le tracking de l’électrode du défibrillateur automatique implantable a permis de délivrer avec succès la radiothérapie stéréotaxique chez tous les patients. Le volume des substrats de la tachycardie ventriculaire était pour chaque patient de 19 cm3, 21 cm3 et 35 cm3. Après un suivi médian de cinq mois, les patients électifs n’ont pas souffert de récidive rythmique. Le patient en réanimation a été extubé trois jours après la radiothérapie stéréotaxique et sans récidive de tempête rythmique pendant quatre mois, avant de présenter un nouvel épisode à 19 semaines. Cet épisode a été imputé à un nouveau substrat de la tachycardie ventriculaire, distant du premier, confirmé par cartographie tridimensionnelle et traité par ablation par cathéter. Il n’y a eu aucune complication imputable à la radiothérapie stéréotaxique. Conclusion La radiothérapie stéréotaxique apparait comme un traitement prometteur des tachycardies ventriculaires et tempête rythmiques réfractaires aux traitements classiques. Un suivi des effets secondaires à long terme reste indispensable. [ABSTRACT FROM AUTHOR]

Purpose: This study explores the dosimetric feasibility and plan quality of hybrid ultra-high dose rate (UHDR) electron and conventional dose rate (CDR) photon (HUC) radiotherapy for treating deep-seated tumours with FLASH-RT., Methods: HUC treatment planning was conducted optimizing a broad UHDR electron beam (between 20-250 MeV) combined with a CDR VMAT for a glioblastoma, a pancreatic cancer, and a prostate cancer case. HUC plans were based on clinical prescription and fractionation schemes and compared against clinically delivered plans. Considering a HUC boost treatment for the glioblastoma consisting of a 15-Gy-single-fraction UHDR electron boost supplemented with VMAT, two scenarios for FLASH sparing were assessed using FLASH-modifying-factor-weighted doses., Results: For all three patient cases, HUC treatment plans demonstrated comparable dosimetric quality to clinical plans, with similar PTV coverage (V 95% within 0.5 %), homogeneity, and critical OAR-sparing. At the same time, HUC plans delivered a substantial portion of the dose to the PTV (D median of 50-69 %) and surrounding tissues at UHDR. For the HUC boost treatment of the glioblastoma, the first FLASH sparing scenario showed a moderate FLASH sparing magnitude (10 % for D 2%,PTV ) for the 15-Gy UHDR electron boost, while the second scenario indicated a more substantial sparing of brain tissues inside and outside the PTV (32 % for D 2%,PTV , 31 % for D 2%,Brain )., Conclusions: From a planning perspective, HUC treatments represent a feasible approach for delivering dosimetrically conformal UHDR treatments, potentially mitigating technical challenges associated with delivering conformal FLASH-RT for deep-seated tumours. While further research is needed to optimize HUC fractionation and delivery schemes for specific patient cohorts, HUC treatments offer a promising avenue for the clinical transfer of FLASH-RT., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Author(s). Published by Elsevier B.V. All rights reserved.)

Purpose: One of the advantages of integrating automated processes in treatment planning is the reduction of manual planning variability. This study aims to assess whether a deep-learning-based auto-planning solution can also reduce the contouring variation-related impact on the planned dose for early-breast cancer treatment., Methods: Auto- and manual plans were optimized for 20 patients using both auto- and manual OARs, including both lungs, right breast, heart, and left-anterior-descending (LAD) artery. Differences in terms of recalculated dose (ΔD rc M ,ΔD rc A ) for manual (M) and auto (A)-plans, were evaluated on manual structures. The correlation between several geometric similarities and dose differences was also explored (Spearman's test).ro M ,ΔD ro A ) for manual (M) and auto (A)-plans, were evaluated on manual structures. The correlation between several geometric similarities and dose differences was also explored (Spearman's test)., Results: Auto-contours were found slightly smaller in size than manual contours for right breast and heart and more than twice larger for LAD. Recalculated dose differences were found negligible for both planning approaches except for heart (ΔD rc M =-0.4 Gy, ΔD rc A =-0.3 Gy) and right breast (ΔD rc M =-1.2 Gy, ΔD rc A =-1.3 Gy) maximum dose. Re-optimized dose differences were considered equivalent to recalculated ones for both lungs and LAD, while they were significantly smaller for heart (ΔD ro (M=8,A=13) that reduced to four for ΔD M (M=3,A=1).ro A =-0.2 Gy) and right breast (ΔD ro M  =-0.3 Gy, ΔD ro A =-0.9 Gy) maximum dose. Twenty-one correlations were found for ΔD rc M,A (M=8,A=13) that reduced to four for ΔD ro M,A (M=3,A=1)., Conclusions: The sensitivity of auto-planning to contouring variation was found not relevant when compared to manual planning, regardless of the method used to calculate the dose differences. Nonetheless, the method employed to define the dose differences strongly affected the correlation analysis resulting highly reduced when dose was reoptimized, regardless of the planning approach., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Associazione Italiana di Fisica Medica e Sanitaria. Published by Elsevier Ltd. All rights reserved.)

Objectives: We investigated spatial patterns between primary and recurrent tumor sites and assessed long-term toxicity after dose escalation stereotactic body radiation therapy (SBRT) to the dominant intra-prostatic nodule (DIN). Materials and methods: In 33 patients with intermediate-high-risk prostate cancer (PCa), doses up to 50 Gy were administered to the DIN. Recurrence sites were determined and compared to the original tumor development sites through multiparametric MRI and 68 Ga-labeled prostate-specific membrane antigen (PSMA) positron emission tomography/computed tomography ( 68 Ga-PSMA-PET/CT) images. Overlap rates, categorized as 75% or higher for full overlap, and 25-74% for partial overlap, were assessed. Long-term toxicity is reported. Results : All patients completed treatment, with only one receiving concomitant androgen deprivation therapy (ADT). Recurrences were diagnosed after a median of 33 months (range: 17-76 months), affecting 13 out of 33 patients (39.4%). Intra-prostatic recurrences occurred in 7 patients (21%), with ≥75% overlap in two, a partial overlap in another two, and no overlap in the remaining three patients. Notably, five patients with intra-prostatic recurrences had synchronous bone and/or lymph node metastases, while six patients had isolated bone or lymph node metastasis without intra-prostatic recurrences. Extended follow-up revealed late grade ≥ 2 GU and GI toxicity in 18% (n = 6) and 6% (n = 2) of the patients. Conclusions : Among patients with intermediate-high-risk PCa undergoing focal dose-escalated SBRT without ADT, DIN recurrences were infrequent. When present, these recurrences were typically located at the original site or adjacent to the initial tumor. Conversely, relapses beyond the DIN and in extra-prostatic (metastatic) sites were prevalent, underscoring the significance of systemic ADT in managing this patient population. Advances in knowledge: Focal dose-escalated prostate SBRT prevented recurrences in the dominant nodule; however, extra-prostatic recurrence sites were frequent.

Background: Studies comparing different radiotherapy treatment techniques-such as volumetric modulated arc therapy (VMAT) and helical tomotherapy (HT)-typically compare one treatment plan per technique. Often, some dose metrics favor one plan and others favor the other, so the final plan decision involves subjective preferences. Pareto front comparisons provide a more objective framework for comparing different treatment techniques. A Pareto front is the set of all treatment plans where improvement in one criterion is possible only by worsening another criterion. However, different Pareto fronts can be obtained depending on the chosen machine settings., Purpose: To compare VMAT and HT using Pareto fronts and blind expert evaluation, to explain the observed differences, and to illustrate limitations of using Pareto fronts., Methods: We generated Pareto fronts for twenty-four prostate cancer patients treated at our clinic for VMAT and HT techniques using an in-house script that controlled a commercial treatment planning system. We varied the PTV under-coverage (100% - V 95% ) and the rectum mean dose, and fixed the mean doses to the bladder and femoral heads. In order to ensure a fair comparison, those fixed mean doses were the same for the two treatment techniques and the sets of objective functions were chosen so that the conformity indexes of the two treatment techniques were also the same. We used the same machine settings as are used in our clinic. Then, we compared the VMAT and HT Pareto fronts using a specific metric (clinical distance measure) and validated the comparison using a blinded expert evaluation of treatment plans on these fronts for all patients in the cohort. Furthermore, we investigated the observed differences between VMAT and HT and pointed out limitations of using Pareto fronts., Results: Both clinical distance and blind treatment plan comparison showed that VMAT Pareto fronts were better than HT fronts. VMAT fronts for 10 and 6 MV beam energy were almost identical. HT fronts improved with different machine settings, but were still inferior to VMAT fronts., Conclusions: That VMAT Pareto fronts are better than HT fronts may be explained by the fact that the linear accelerator can rapidly vary the dose rate. This is an advantage in simple geometries that might vanish in more complex geometries. Furthermore, one should be cautious when speaking about Pareto optimal plans as the best possible plans, as their calculation depends on many parameters., (© 2023 The Authors. Medical Physics published by Wiley Periodicals LLC on behalf of American Association of Physicists in Medicine.)

Purpose: In inverse radiotherapy treatment planning, the Pareto front is the set of optimal solutions to the multi-criteria problem of adequately irradiating the planning target volume (PTV) while reducing dose to organs at risk (OAR). The Pareto front depends on the chosen optimisation parameters whose influence (clinically relevant versus not clinically relevant) is investigated in this paper., Methods: Thirty-one prostate cancer patients treated at our clinic were randomly selected. We developed an in-house Python script that controlled the commercial treatment planning system RayStation to calculate directly deliverable Pareto fronts. We calculated reference Pareto fronts for a given set of objective functions, varying the PTV coverage and the mean dose of the primary OAR (rectum) and fixing the mean doses of the secondary OARs (bladder and femoral heads). We calculated the fronts for different sets of objective functions and different mean doses to secondary OARs. We compared all fronts using a specific metric (clinical distance measure)., Results: The in-house script was validated for directly deliverable Pareto front calculations in two and three dimensions. The Pareto fronts depended on the choice of objective functions and fixed mean doses to secondary OARs, whereas the parameters most influencing the front and leading to clinically relevant differences were the dose gradient around the PTV, the weight of the PTV objective function, and the bladder mean dose., Conclusions: Our study suggests that for multi-criteria optimisation of prostate treatments using external therapy, dose gradient around the PTV and bladder mean dose are the most influencial parameters., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Associazione Italiana di Fisica Medica e Sanitaria. Published by Elsevier Ltd. All rights reserved.)

Background and Purpose: Automation in radiotherapy treatment planning aims to improve both the quality and the efficiency of the process. The aim of this study was to report on a clinical implementation of a Deep Learning (DL) auto-planning model for left-sided breast cancer., Materials and Methods: The DL model was developed for left-sided breast simultaneous integrated boost treatments under deep-inspiration breath-hold. Eighty manual dose distributions were revised and used for training. Ten patients were used for model validation. The model was then used to design 17 clinical auto-plans. Manual and auto-plans were scored on a list of clinical goals for both targets and organs-at-risk (OARs). For validation, predicted and mimicked dose (PD and MD, respectively) percent error (PE) was calculated with respect to manual dose. Clinical and validation cohorts were compared in terms of MD only., Results: Median values of both PD and MD validation plans fulfilled the evaluation criteria. PE was < 1% for targets for both PD and MD. PD was well aligned to manual dose while MD left lung mean dose was significantly less (median:5.1 Gy vs 6.1 Gy). The left-anterior-descending artery maximum dose was found out of requirements (median values:+5.9 Gy and + 2.9 Gy, for PD and MD respectively) in three validation cases, while it was reduced for clinical cases (median:-1.9 Gy). No other clinically significant differences were observed between clinical and validation cohorts., Conclusion: Small OAR differences observed during the model validation were not found clinically relevant. The clinical implementation outcomes confirmed the robustness of the model., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2023 The Author(s).)