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PURPOSE AND OBJECTIVE: To develop expert consensus statements on multiparametric dose prescriptions for stereotactic body radiotherapy (SBRT) aligning with ICRU report 91. These statements serve as a foundational step towards harmonizing current SBRT practices and refining dose prescription and documentation requirements for clinical trial designs. MATERIALS AND METHODS: Based on the results of a literature review by the working group, a two-tier Delphi consensus process was conducted among 24 physicians and physics experts from three European countries. The degree of consensus was predefined for overarching (OA) and organ-specific (OS) statements (≥â¯80%, 60-79%, <â¯60% for high, intermediate, and poor consensus, respectively). Post-first round statements were refined in a live discussion for the second round of the Delphi process. RESULTS: Experts consented on a total of 14 OA and 17 OS statements regarding SBRT of primary and secondary lung, liver, pancreatic, adrenal, and kidney tumors regarding dose prescription, target coverage, and organ at risk dose limitations. Degree of consent wasâ¯≥ 80% in 79% and 41% of OA and OS statements, respectively, with higher consensus for lung compared to the upper abdomen. In round 2, the degree of consent wasâ¯≥ 80 to 100% for OA and 88% in OS statements. No consensus was reached for dose escalation to liver metastases after chemotherapy (47%) or single-fraction SBRT for kidney primaries (13%). In round 2, no statement had 60-79% consensus. CONCLUSION: In 29 of 31 statements a high consensus was achieved after a two-tier Delphi process and one statement (kidney) was clearly refused. The Delphi process was able to achieve a high degree of consensus for SBRT dose prescription. In summary, clear recommendations for both OA and OS could be defined. This contributes significantly to harmonization of SBRT practice and facilitates dose prescription and reporting in clinical trials investigating SBRT.
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Hepatocellular carcinoma (HCC) is the sixth most common neoplasia and the third leading cause of cancer-associated deaths worldwide. Most cases arise in patients with cirrhosis, and early detection through periodic screening can make it potentially curable. The presence of extrahepatic metastases (EHM) affects treatment decisions and curability. The lungs are the most common site for EHM, followed by lymph nodes, bones, and the adrenal glands. Interestingly, approximately only 15 cases of HCC metastasizing to the pituitary gland have been reported so far.The most common symptoms of pituitary metastasis (PM) arising from HCC are nerve palsies affecting the third, fourth, and sixth cranial nerves. Other symptoms, such as diabetes insipidus or pituitary insufficiencies, are present in a minority of cases. Detecting PM is difficult given its rarity. Gold-standard treatments for these patients have not yet been established, but the prognosis is dismal, with a median overall survival of only 4.5 months. In this paper, we present an interesting case of PM as the first symptom of an HCC in a 75-year-old female. We also present an overview of all cases reported to date with emphasis on symptom presentation and survival after diagnosis.Given the improvement of systemic therapy, more cases are diagnosed in both oligometastatic and palliative conditions. Therefore, better approaches and treatment modalities for extrahepatic metastases due to HCC should be defined.
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Carcinoma Hepatocelular , Neoplasias Hepáticas , Neoplasias Hipofisarias , Humanos , Neoplasias Hepáticas/secundario , Neoplasias Hepáticas/diagnóstico , Neoplasias Hepáticas/patología , Carcinoma Hepatocelular/secundario , Carcinoma Hepatocelular/patología , Femenino , Anciano , Neoplasias Hipofisarias/secundario , Neoplasias Hipofisarias/patología , Neoplasias Hipofisarias/terapia , Neoplasias Hipofisarias/diagnóstico , Diagnóstico Diferencial , Resultado del TratamientoRESUMEN
BACKGROUND: Electroanatomical mapping (EAM)-guided stereotactic arrhythmia radioablation (STAR) is a novel noninvasive therapy option for patients with monomorphic ventricular tachycardia (VT) refractory to antiarrhythmic drugs and/or urgent catheter ablation (CA). Data on success rates in an emergency situation such as electrical storm (ES) are rare. We present a case of a patient with an initially very poor life expectancy after extensive myocardial infarction with therapy-resistant ES, not amendable for further antiarrhythmic drug therapy, implantable cardioverter-defibrillator implantation, or repeated CA who was introduced to the radiation oncology department for emergency STAR as a bail-out therapy. METHODS: Target volume definition and transfer from EAM to CT were validated and quality assured with a semi-automatic, dedicated visualization tool (CARDIO-RT). Emergency STAR was performed with 25â¯Gy in the framework of the RAVENTA study. The VT burden gradually decreased after STAR; however, a second VT morphology occurred, which was successfully treated with EAM-guided CA 12 days after STAR. RESULTS: The second EAM-guided CA showed areas of low voltage in the irradiated segments, indicating a precise targeting and early functional response to STAR. The patient remained free of any VT recurrence or any radiation-related toxicities and in good general condition during the recent follow-up of 18 months. CONCLUSION: The case highlights the possible approach, caveats, difficulties, and prognosis of a patient severely affected by therapy-resistant VT in whom CA could not lead to VT suppression. Further studies of putative mechanisms of STAR in the acute and chronic phase of this novel therapy are warranted.
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Ablación por Catéter , Taquicardia Ventricular , Humanos , Taquicardia Ventricular/radioterapia , Taquicardia Ventricular/cirugía , Antiarrítmicos/uso terapéutico , Corazón , Ablación por Catéter/efectos adversos , Pronóstico , Resultado del TratamientoRESUMEN
BACKGROUND: Single-session cardiac stereotactic radiation therapy (SBRT) has demonstrated promising results for patients with refractory ventricular tachycardia (VT). However, the full safety profile of this novel treatment remains unknown and very limited data from prospective clinical multicenter trials are available. METHODS: The prospective multicenter multiplatform RAVENTA (radiosurgery for ventricular tachycardia) study assesses high-precision image-guided cardiac SBRT with 25â¯Gy delivered to the VT substrate determined by high-definition endocardial and/or epicardial electrophysiological mapping in patients with refractory VT ineligible for catheter ablation and an implanted cardioverter defibrillator (ICD). Primary endpoint is the feasibility of full-dose application and procedural safety (defined as an incidence of serious [grade ≥â¯3] treatment-related complications ≤â¯5% within 30 days after therapy). Secondary endpoints comprise VT burden, ICD interventions, treatment-related toxicity, and quality of life. We present the results of a protocol-defined interim analysis. RESULTS: Between 10/2019 and 12/2021, a total of five patients were included at three university medical centers. In all cases, the treatment was carried out without complications. There were no serious potentially treatment-related adverse events and no deterioration of left ventricular ejection fraction upon echocardiography. Three patients had a decrease in VT episodes during follow-up. One patient underwent subsequent catheter ablation for a new VT with different morphology. One patient with local VT recurrence died 6 weeks after treatment in cardiogenic shock. CONCLUSION: The interim analysis of the RAVENTA trial demonstrates early initial feasibility of this new treatment without serious complications within 30 days after treatment in five patients. Recruitment will continue as planned and the study has been expanded to further university medical centers. TRIAL REGISTRATION NUMBER: NCT03867747 (clinicaltrials.gov). Registered March 8, 2019. Study start: October 1, 2019.
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Radiocirugia , Taquicardia Ventricular , Humanos , Radiocirugia/métodos , Volumen Sistólico , Estudios Prospectivos , Calidad de Vida , Estudios de Factibilidad , Función Ventricular Izquierda , Taquicardia Ventricular/radioterapia , Taquicardia Ventricular/cirugía , Resultado del TratamientoRESUMEN
The EU Horizon 2020 Framework-funded Standardized Treatment and Outcome Platform for Stereotactic Therapy Of Re-entrant tachycardia by a Multidisciplinary (STOPSTORM) consortium has been established as a large research network for investigating STereotactic Arrhythmia Radioablation (STAR) for ventricular tachycardia (VT). The aim is to provide a pooled treatment database to evaluate patterns of practice and outcomes of STAR and finally to harmonize STAR within Europe. The consortium comprises 31 clinical and research institutions. The project is divided into nine work packages (WPs): (i) observational cohort; (ii) standardization and harmonization of target delineation; (iii) harmonized prospective cohort; (iv) quality assurance (QA); (v) analysis and evaluation; (vi, ix) ethics and regulations; and (vii, viii) project coordination and dissemination. To provide a review of current clinical STAR practice in Europe, a comprehensive questionnaire was performed at project start. The STOPSTORM Institutions' experience in VT catheter ablation (83% ≥ 20 ann.) and stereotactic body radiotherapy (59% > 200 ann.) was adequate, and 84 STAR treatments were performed until project launch, while 8/22 centres already recruited VT patients in national clinical trials. The majority currently base their target definition on mapping during VT (96%) and/or pace mapping (75%), reduced voltage areas (63%), or late ventricular potentials (75%) during sinus rhythm. The majority currently apply a single-fraction dose of 25 Gy while planning techniques and dose prescription methods vary greatly. The current clinical STAR practice in the STOPSTORM consortium highlights potential areas of optimization and harmonization for substrate mapping, target delineation, motion management, dosimetry, and QA, which will be addressed in the various WPs.
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Ablación por Catéter , Taquicardia Ventricular , Humanos , Estudios Prospectivos , Arritmias Cardíacas , Ventrículos Cardíacos , Ablación por Catéter/efectos adversos , Ablación por Catéter/métodos , Resultado del TratamientoRESUMEN
BACKGROUND: Stereotactic body radiotherapy (SBRT) is an effective therapeutic approach in patients with liver metastases. However, long-term changes in hepatic normal tissue have to be taken into account in multimodal treatment regimes. Magnetic-resonance-imaging (MRI) based morphologic liver alterations (MMA) after liver SBRT have been analyzed longitudinally. MATERIAL AND METHODS: 57 patients treated with gantry-based or robotic-based SBRT of 69 treatment volumes of liver metastases, who had long-term follow-up (FU) ≥6 months were included in this retrospective analysis. Post-SBRT MMAs were contoured on each contrast-enhanced-T1-weighted (T1w) MRI-sequence. Morphologic/volumetric data of the liver and MMAs were evaluated longitudinally, including the dependency on treatment-related factors of the planning target volume (PTV) and liver. RESULTS: The median FU time was 1 year [6-48 months]. 66 of 69 treatment volumes developed MMAs (mean 143.8 ± 135.1 ccm at first appearance). 31.8% of MMAs resolved completely during FU. Of the persisting MMAs 82.2%/13.3% decreased/increased in size until last available FU. Morphological characterization of the MMAs at first appearance included 75% hypointense and 25% hyperintense T1w-MRI-based appearances. Hypointense as compared to hyperintense appearance was significantly associated with a higher mean liver dose EQD2α/ß=3 Gy (p = 0.0212) and non-significantly greater MMA size. Variance analysis demonstrated a significant reduction of MMA and total liver volume after SBRT (p < 0.0001). The volume reduction decelerated longitudinally for both MMA (p < 0.0001) and liver size (p = 0.0033). Radiation doses (PTV-BEDα/ß=3 Gy and 10 Gy) were not significantly associated with MMA volume reduction. SBRT of liver metastases with mean liver dose EQD2α/ß=3 Gy > 18 Gy were characterized by greater MMA volumes (p = 0.0826) and steeper MMA reduction gradients during FU than those with EQD2α/ß=3 Gy ≤ 18 Gy (p < 0.0001). CONCLUSION: Radiogenic MMAs either completely resolve or usually decrease in volume with pronounced reduction during short-term FU. This course was independent of the MMA's morphological appearance. Further, increased mean liver dose was associated with greater MMA size and a greater gradient of MMA size reduction during FU.
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Neoplasias Hepáticas , Radiocirugia , Humanos , Radiocirugia/efectos adversos , Radiocirugia/métodos , Estudios Retrospectivos , Neoplasias Hepáticas/diagnóstico por imagen , Neoplasias Hepáticas/radioterapia , Neoplasias Hepáticas/patología , Imagen por Resonancia Magnética , Dosificación RadioterapéuticaRESUMEN
Optimal doses for the treatment of adrenal metastases with stereotactic radiotherapy (SBRT) are unknown. We aimed to identify dose-volume cut-points associated with decreased local recurrence rates (LRR). A multicenter database of patients with adrenal metastases of any histology treated with SBRT (biologically effective dose, BED10 ≥50 Gy, ≤12 fractions) was analyzed. Details on dose-volume parameters were required (planning target volume: PTV-D98%, PTV-D50%, PTV-D2%; gross tumor volume: GTV-D50%, GTV-mean). Cut-points for LRR were optimized using the R maxstat package. One hundred and ninety-six patients with 218 lesions were included, the largest histopathological subgroup was adenocarcinoma (n = 101). Cut-point optimization resulted in significant cut-points for PTV-D50% (BED10: 73.2 Gy; P = .003), GTV-D50% (BED10: 74.2 Gy; P = .006), GTV-mean (BED10: 73.0 Gy; P = .007), and PTV-D2% (BED10: 78.0 Gy; P = .02) but not for the PTV-D98% (P = .06). Differences in LRR were clinically relevant (LRR ≥ doubled for cut-points that were not achieved). Further dose-escalation was not associated with further improved LRR. PTV-D50%, GTV-D50%, and GTV-mean cut-points were also associated with significantly improved LRR in the adenocarcinoma subgroup. Separate dose optimizations indicated a lower cut-point for the PTV-D50% (BED10: 69.1 Gy) in adenocarcinoma lesions, other values were similar (<2% difference). Associations of cut-points with overall survival (OS) and progression-free survival were not significant but durable freedom from local recurrence was associated with OS in a landmark model (P < .001). To achieve a significant improvement of LRR for adrenal SBRT, a moderate escalation of PTV-D50% BED10 >73.2 Gy (adenocarcinoma: 69.1 Gy) should be considered.
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Adenocarcinoma , Neoplasias de las Glándulas Suprarrenales , Neoplasias Pulmonares , Neoplasias Primarias Secundarias , Radiocirugia , Adenocarcinoma/radioterapia , Neoplasias de las Glándulas Suprarrenales/radioterapia , Neoplasias de las Glándulas Suprarrenales/secundario , Humanos , Neoplasias Pulmonares/patología , Radiocirugia/métodos , Dosificación Radioterapéutica , Estudios RetrospectivosRESUMEN
To report outcome (freedom from local progression [FFLP], overall survival [OS] and toxicity) after stereotactic, palliative or highly conformal fractionated (>12) radiotherapy (SBRT, Pall-RT, 3DCRT/IMRT) for adrenal metastases in a retrospective multicenter cohort within the framework of the German Society for Radiation Oncology (DEGRO). Adrenal metastases treated with SBRT (≤12 fractions, biologically effective dose [BED10] ≥ 50 Gy), 3DCRT/IMRT (>12 fractions, BED10 ≥ 50 Gy) or Pall-RT (BED10 < 50 Gy) were eligible for this analysis. In addition to unadjusted FFLP (Kaplan-Meier/log-rank), we calculated the competing-risk-adjusted local recurrence rate (CRA-LRR). Three hundred twenty-six patients with 366 metastases were included by 21 centers (median follow-up: 11.7 months). Treatment was SBRT, 3DCRT/IMRT and Pall-RT in 260, 27 and 79 cases, respectively. Most frequent primary tumors were non-small-cell lung cancer (NSCLC; 52.5%), SCLC (16.3%) and melanoma (6.7%). Unadjusted FFLP was higher after SBRT vs Pall-RT (P = .026) while numerical differences in CRA-LRR between groups did not reach statistical significance (1-year CRA-LRR: 13.8%, 17.4% and 27.7%). OS was longer after SBRT vs other groups (P < .05) and increased in patients with locally controlled metastases in a landmark analysis (P < .0001). Toxicity was mostly mild; notably, four cases of adrenal insufficiency occurred, two of which were likely caused by immunotherapy or tumor progression. Radiotherapy for adrenal metastases was associated with a mild toxicity profile in all groups and a favorable 1-year CRA-LRR after SBRT or 3DCRT/IMRT. One-year FFLP was associated with longer OS. Dose-response analyses for the dataset are underway.
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Neoplasias de las Glándulas Suprarrenales/radioterapia , Neoplasias de las Glándulas Suprarrenales/secundario , Carcinoma de Pulmón de Células no Pequeñas/radioterapia , Neoplasias Pulmonares/radioterapia , Carcinoma Pulmonar de Células Pequeñas/radioterapia , Anciano , Anciano de 80 o más Años , Bases de Datos Factuales , Femenino , Humanos , Masculino , Persona de Mediana Edad , Cuidados Paliativos , Radiocirugia , Dosificación Radioterapéutica , Radioterapia Conformacional , Estudios Retrospectivos , Análisis de Supervivencia , Resultado del TratamientoRESUMEN
Current research, especially in oncology, increasingly focuses on the integration of quantitative, multiparametric and functional imaging data. In this fast-growing field of research, radiomics may allow for a more sophisticated analysis of imaging data, far beyond the qualitative evaluation of visible tissue changes. Through use of quantitative imaging data, more tailored and tumour-specific diagnostic work-up and individualized treatment concepts may be applied for oncologic patients in the future. This is of special importance in cross-sectional disciplines such as radiology and radiation oncology, with already high and still further increasing use of imaging data in daily clinical practice. Liver targets are generally treated with stereotactic body radiotherapy (SBRT), allowing for local dose escalation while preserving surrounding normal tissue. With the introduction of online target surveillance with implanted markers, 3D-ultrasound on conventional linacs and hybrid magnetic resonance imaging (MRI)-linear accelerators, individualized adaptive radiotherapy is heading towards realization. The use of big data such as radiomics and the integration of artificial intelligence techniques have the potential to further improve image-based treatment planning and structured follow-up, with outcome/toxicity prediction and immediate detection of (oligo)progression. The scope of current research in this innovative field is to identify and critically discuss possible application forms of radiomics, which is why this review tries to summarize current knowledge about interdisciplinary integration of radiomics in oncologic patients, with a focus on investigations of radiotherapy in patients with liver cancer or oligometastases including multiparametric, quantitative data into (radio)-oncologic workflow from disease diagnosis, treatment planning, delivery and patient follow-up.
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Biología Computacional , Procesamiento de Imagen Asistido por Computador/métodos , Neoplasias Hepáticas/diagnóstico por imagen , Oncología por Radiación/métodos , Cuidados Posteriores , Quimioembolización Terapéutica , Terapia Combinada , Aprendizaje Profundo , Humanos , Neoplasias Hepáticas/secundario , Neoplasias Hepáticas/terapia , Órganos en Riesgo , Pronóstico , Radiocirugia , Dosificación Radioterapéutica , Planificación de la Radioterapia Asistida por Computador/métodos , Radioterapia Guiada por Imagen , Cirugía Asistida por ComputadorRESUMEN
In this review, the current state of stereotactic body radiation therapy (SBRT) is presented as a local therapy for patients with oligometastatic, oligoprogressive and oligorecurrent liver metastases - focusing on recent publications from German-speaking countries. In addition to precise imaging, modern SBRT techniques also use gating and tracking techniques that have made local therapy of liver metastases more effective. In combination with optimisation of central tumour dose, local control rates of up to 90% have been achieved with minimal side effects in less than 1% of patients and 5-year survival rates of more than 30% in selected (inoperable) patient populations. In future, hybrid ultrasound or MRI irradiation systems can overcome fiducial marker implantation. Due to the current outcome data, SBRT is a valuable addition to the therapeutic armamentarium for patients with liver metastases and is a true alternative to minimally invasive ablative procedures or can be used in combination with other local or systemic treatments in an interdisciplinary context.
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Neoplasias Hepáticas , Radiocirugia , Humanos , Neoplasias Hepáticas/terapia , Tasa de SupervivenciaRESUMEN
BACKGROUND AND PURPOSE: In this retrospective treatment planning study, the effect of a uniform and non-uniform planning target volume (PTV) dose coverage as well as a coplanar and non-coplanar volumetric modulated arc therapy (VMAT) delivery approach for lung stereotactic body radiation therapy (SBRT) in deep inspiration breath-hold (DIBH) were compared. MATERIALS AND METHODS: For 46 patients with lesions in the peripheral lungs, three different treatment plans were generated: First, a coplanar 220° VMAT sequence with a uniform PTV dose prescription (UC). Second, a coplanar 220° VMAT treatment plan with a non-uniform dose distribution in the PTV (nUC). Third, a non-coplanar VMAT dose delivery with four couch angles (0°, ±35°, 90°) and a non-uniform prescription (nUnC) was used. All treatment plans were optimized for pareto-optimality with respect to PTV coverage and ipsilateral lung dose. Treatment sequences were delivered on a flattening-filter-free linear accelerator and beam-on times were recorded. Dosimetric comparison between the three techniques was performed. RESULTS: For the three scenarios (UC, nUC, nUnC), median gross tumor volume (GTV) doses were 63.4⯱ 2.5, 74.4⯱ 3.6, and 77.9⯱ 3.8 Gy, and ipsilateral V10Gy lung volumes were 15.7⯱ 6.1, 13.9⯱ 4.7, and 12.0⯱ 5.1%, respectively. Normal tissue complication probability of the ipsilateral lung was 3.9, 3.1, and 2.8%, respectively. The number of monitor units were 5141⯱ 1174, 4104⯱ 786, and 3657⯱ 710 MU and the corresponding beam-on times were 177⯱ 54, 143⯱ 29, and 148⯱ 26 s. CONCLUSION: For SBRT treatments in DIBH, a non-uniform dose prescription in the PTV, combined with a non-coplanar VMAT arc arrangement, significantly spares the ipsilateral lung while increasing dose to the GTV without major treatment time increase.
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Carcinoma de Pulmón de Células no Pequeñas/radioterapia , Fraccionamiento de la Dosis de Radiación , Neoplasias Pulmonares/radioterapia , Radiocirugia , Planificación de la Radioterapia Asistida por Computador , Radioterapia de Intensidad Modulada , Adulto , Anciano , Contencion de la Respiración , Carcinoma de Pulmón de Células no Pequeñas/mortalidad , Femenino , Humanos , Pulmón/efectos de la radiación , Neoplasias Pulmonares/mortalidad , Persona de Mediana Edad , Dosificación Radioterapéutica , Tasa de Supervivencia , Carga Tumoral/efectos de la radiaciónRESUMEN
PURPOSE: In radiation therapy, the computer-assisted deep inspiration breath-hold (DIBH) technique is one approach to deal with respiratory motion of tumors in the lung, liver, or upper abdomen. However, inter- and intra-breath-hold deviations from an optimal static tumor position might occur. A novel method is presented to noninvasively measure the diaphragm position and thus estimate its residual deviation (as surrogate for the tumor position) based on cone-beam computed tomography (CBCT) projection data using active breathing control during acquisition. METHODS: The diaphragm dome (DD) position relative to the isocenter of a linear accelerator is known from the static (DIBH) planning CT. A ball-bearing phantom (BB) is placed at this position, a CBCT dataset is acquired, and in each projection the position of the projected BB is determined automatically based on thresholding. The position of the DD is determined manually in CBCT projections of a patient. The distance between DD and BB (ideal static setting) in craniocaudal direction is calculated for a given angle based on the distance in the projection plane and the relative position of the BB referring to the source and the detector. An angle-dependent correction factor is introduced which takes this geometrical setting into account. The accuracy of the method is assessed. RESULTS: The method allows a CBCT projection-based estimation of the deviation between the DD and its optimal position as defined in the planning CT, i.e., the residual motion of the DD can be assessed. The error of this estimation is 2.2â¯mm in craniocaudal direction. CONCLUSIONS: The developed method allows an offline estimation of the inspiration depth (inter- and intra-breath-hold) over time. It will be useful as a reference for comparison to other methods of residual motion estimation, e.g., surface scanning.
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Neoplasias Abdominales/radioterapia , Contencion de la Respiración , Tomografía Computarizada de Haz Cónico , Diafragma , Neoplasias Hepáticas/radioterapia , Neoplasias Pulmonares/radioterapia , Movimientos de los Órganos , Humanos , Posicionamiento del Paciente , Fantasmas de Imagen , Planificación de la Radioterapia Asistida por Computador , Sensibilidad y EspecificidadRESUMEN
PURPOSE: For assessing healthy liver reactions after robotic SBRT (stereotactic body radiotherapy), we investigated early morphologic alterations on MRI (magnetic resonance imaging) with respect to patient and treatment plan parameters. PATIENTS AND METHODS: MRI data at 6-17 weeks post-treatment from 22 patients with 42 liver metastases were analyzed retrospectively. Median prescription dose was 40â¯Gy delivered in 3-5 fractions. T2- and T1-weighted MRI were registered to the treatment plan. Absolute doses were converted to EQD2 (Equivalent dose in 2Gy fractions) with α/ß-ratios of 2 and 3â¯Gy for healthy, and 8â¯Gy for modelling pre-damaged liver tissue. RESULTS: Sharply defined, centroid-shaped morphologic alterations were observed outside the high-dose volume surrounding the GTV. On T2-w MRI, hyperintensity at EQD2 isodoses of 113.3⯱ 66.1â¯Gy2, 97.5⯱ 54.7â¯Gy3, and 66.5⯱ 32.0â¯Gy8 significantly depended on PTV dimension (pâ¯= 0.02) and healthy liver EQD2 (pâ¯= 0.05). On T1-w non-contrast MRI, hypointensity at EQD2 isodoses of 113.3⯱ 49.3â¯Gy2, 97.4⯱ 41.0â¯Gy3, and 65.7⯱ 24.2â¯Gy8 significantly depended on prior chemotherapy (pâ¯= 0.01) and total liver volume (pâ¯= 0.05). On T1-w gadolinium-contrast delayed MRI, hypointensity at EQD2 isodoses of 90.6⯱ 42.5â¯Gy2, 79.3⯱ 35.3â¯Gy3, and 56.6⯱ 20.9â¯Gy8 significantly depended on total (pâ¯= 0.04) and healthy (pâ¯= 0.01) liver EQD2. CONCLUSIONS: Early post-treatment changes in healthy liver tissue after robotic SBRT could spatially be correlated to respective isodoses. Median nominal doses of 10.1-11.3â¯Gy per fraction (EQD2 79-97â¯Gy3) induce characteristic morphologic alterations surrounding the lesions, potentially allowing for dosimetric in-vivo accuracy assessments. Comparison to other techniques and investigations of the short- and long-term clinical impact require further research.