RESUMEN
Brainstem metastases are challenging to manage owing to the critical neurological structures involved. Although stereotactic radiotherapy (SRT) offers targeted high doses while minimizing damage to adjacent normal tissues, the optimal dose fractionation remains undefined. This study evaluated the efficacy and safety of multifraction SRT with an inhomogeneous dose distribution. This retrospective study included 31 patients who underwent 33 treatments for 35 brainstem lesions using linear accelerator-based multifraction SRT (30 Gy in five fractions, 35 Gy in five fractions or 42 Gy in 10 fractions) with an inhomogeneous dose distribution (median isodose, 51.9%). The outcomes of interest were local failure, toxicity and symptomatic failure. The median follow-up time after brainstem SRT for a lesion was 18.6 months (interquartile range, 10.0-24.3 months; range, 1.8-39.0 months). Grade 2 toxicities were observed in two lesions, and local failure occurred in three lesions. No grade 3 or higher toxicities were observed. The 1-year local and symptomatic failure rates were 8.8 and 16.7%, respectively. Toxicity was observed in two of seven treatments with a gross tumor volume (GTV) greater than 1 cc, whereas no toxicity was observed in treatments with a GTV less than 1 cc. No clear association was observed between the biologically effective dose of the maximum brainstem dose and the occurrence of toxicity. Our findings indicate that multifraction SRT with an inhomogeneous dose distribution offers a favorable balance between local control and toxicity in brainstem metastases. Larger multicenter studies are needed to validate these results and determine the optimal dose fractionation.
RESUMEN
BACKGROUND: Fractionated stereotactic radiosurgery (fSRS) is an important treatment strategy for unresected brain metastases. We previously reported that a good volumetric response 6 months after fSRS can be the first step for local control. Few studies have reported the association between gross tumor volume (GTV) dose, volumetric response, and local control in patients treated with the same number of fractions. Therefore, in this study, we aimed to investigate the GTV dose and volumetric response 6 months after fSRS in five daily fractions and identify the predictive GTV dose for local failure (LF) for unresected brain metastasis. METHODS: This retrospective study included 115 patients with 241 unresected brain metastases treated using fSRS in five daily fractions at our hospital between January 2013 and April 2022. The median prescription dose was 35 Gy (range, 30-35 Gy) in five fractions. The median follow-up time after fSRS was 16 months (range, 7-66 months). RESULTS: GTV D80 > 42 Gy and GTV D98 > 39 Gy were prognostic factors for over 65% volume reduction (odds ratio, 3.68, p < 0.01; odds ratio, 4.68, p < 0.01, respectively). GTV D80 > 42 Gy was also a prognostic factor for LF (hazard ratio, 0.37; p = 0.01). CONCLUSIONS: GTV D80 > 42 Gy in five fractions led to better volume reduction and local control. The goal of planning an inhomogeneous dose distribution for fSRS in brain metastases may be to increase the GTV D80 and GTV D98. Further studies on inhomogeneous dose distributions are required.
Asunto(s)
Neoplasias Encefálicas , Fraccionamiento de la Dosis de Radiación , Radiocirugia , Carga Tumoral , Humanos , Radiocirugia/métodos , Neoplasias Encefálicas/secundario , Neoplasias Encefálicas/radioterapia , Neoplasias Encefálicas/cirugía , Femenino , Masculino , Estudios Retrospectivos , Persona de Mediana Edad , Anciano , Adulto , Anciano de 80 o más Años , Pronóstico , Adulto Joven , Dosificación RadioterapéuticaRESUMEN
BACKGROUND/AIM: Intensity-modulated radiation therapy can deliver a highly conformal dose to a target while minimizing the dose to the organs at risk (OARs). Delineating the contours of OARs is time-consuming, and various automatic contouring software programs have been employed to reduce the delineation time. However, some software operations are manual, and further reduction in time is possible. This study aimed to automate running atlas-based auto-segmentation (ABAS) and software operations using a scripting function, thereby reducing work time. MATERIALS AND METHODS: Dice coefficient and Hausdorff distance were used to determine geometric accuracy. The manual delineation, automatic delineation, and modification times were measured. While modifying the contours, the degree of subjective correction was rated on a four-point scale. RESULTS: The model exhibited generally good geometric accuracy. However, some OARs, such as the chiasm, optic nerve, retina, lens, and brain require improvement. The average contour delineation time was reduced from 57 to 29 min (p<0.05). The subjective revision degree results indicated that all OARs required minor modifications; only the submandibular gland, thyroid, and esophagus were rated as modified from scratch. CONCLUSION: The ABAS model and scripted automation in head and neck cancer reduced the work time and software operations. The time can be further reduced by improving contour accuracy.
Asunto(s)
Neoplasias de Cabeza y Cuello , Órganos en Riesgo , Planificación de la Radioterapia Asistida por Computador , Radioterapia de Intensidad Modulada , Programas Informáticos , Humanos , Neoplasias de Cabeza y Cuello/radioterapia , Planificación de la Radioterapia Asistida por Computador/métodos , Radioterapia de Intensidad Modulada/métodos , Dosificación Radioterapéutica , Algoritmos , Procesamiento de Imagen Asistido por Computador/métodosRESUMEN
PURPOSE: The study aimed to investigate the optimal isodose line (IDL) in linear accelerator-based stereotactic radiotherapy for single brain metastasis, using HyperArc. We compared the dosimetric parameters for target and normal brain tissue among six plans with different IDLs. METHODS: This study included 30 patients with single brain metastasis. We retrospectively generated six plans for each tumor with different IDLs (80%, 70%, 60%, 50%, 40%, and 33%) using HyperArc. All treatment plans were normalized to the prescription dose of 35 Gy in five fractions which was covered by 95% of the planning target volume (PTV), defined by adding a 1.0 mm margin to the gross tumor volume (GTV). The dosimetric parameters were compared among the six plans. RESULTS: For GTV > 0.1 cm3, the ratio of brain-GTV volumes receiving 25 Gy to PTV (V25Gy/PTV) was significantly lower at IDL 40%-70% than at IDL 80% and 33% (p < 0.01, retrospectively). For GTV < 0.1 cm3, V25Gy/PTV decreased continuously as IDL decreased. The values of D99% and D80% for GTV increased with decreasing IDL. An IDL of 50% or less was required to achieve D99% of greater than 43 Gy and D80% of greater than 50 Gy. The mean values of D99% and D80% for IDL 50% were 44.3 and 51.9 Gy. CONCLUSION: The optimal IDL is 40%-50% for GTV > 0.1 cm3. These lower IDLs could increase D99% and D80% of GTV while lowering V25Gy of normal brain tissue, which may help reduce the risk of radiation necrosis and improve local control.
RESUMEN
Postoperative radiotherapy for breast cancer reportedly increases the risk of thoracic soft tissue sarcomas, particularly angiosarcomas; however, the risk in the Japanese population remains unknown. Therefore, this study aimed to investigate the incidence of thoracic soft tissue sarcoma among patients with breast cancer in Japan and determine its association with radiotherapy. This retrospective cohort study used data from the population-based cancer registry of the Osaka Prefecture. The inclusion criteria were female sex, age 20-84 years, diagnosis of breast cancer between 1990 and 2010, no supraclavicular lymph node or distant metastasis, underwent surgery and survived for at least 1 year. The primary outcome was the occurrence of thoracic soft tissue sarcomas 1 year or later after breast cancer diagnosis. Among the 13 762 patients who received radiotherapy, 15 developed thoracic soft tissue sarcomas (nine angiosarcomas and six other sarcomas), with a median time of 7.7 years (interquartile range, 4.0-8.6 years) after breast cancer diagnosis. Among the 27 658 patients who did not receive radiotherapy, four developed thoracic soft tissue sarcomas (three angiosarcomas and one other sarcoma), with a median time of 11.6 years after diagnosis. The 10-year cumulative incidence was higher in the radiotherapy cohort than in the non-radiotherapy cohort (0.087 vs. 0.0036%, P < 0.001). Poisson regression analysis revealed that radiotherapy increased the risk of thoracic soft tissue sarcoma (relative risk, 6.8; 95% confidence interval, 2.4-24.4). Thus, although rare, breast cancer radiotherapy is associated with an increased risk of thoracic soft tissue sarcoma in the Japanese population.
Asunto(s)
Neoplasias de la Mama , Neoplasias Inducidas por Radiación , Sarcoma , Humanos , Femenino , Persona de Mediana Edad , Japón/epidemiología , Anciano , Sarcoma/radioterapia , Sarcoma/epidemiología , Adulto , Neoplasias de la Mama/radioterapia , Neoplasias de la Mama/epidemiología , Anciano de 80 o más Años , Incidencia , Neoplasias Inducidas por Radiación/epidemiología , Adulto Joven , Factores de Riesgo , Neoplasias Torácicas/radioterapia , Estudios de CohortesRESUMEN
In linear accelerator-based stereotactic irradiation (STI) for brain metastasis, cone-beam computed tomography (CBCT) image quality is essential for ensuring precise patient setup and tumor localization. However, CBCT images may be degraded by the deviation of the CBCT isocenter from the brain center. This study aims to investigate the effects of the distance from the brain center to the CBCT isocenter (DBI) on the image quality in STI. An anthropomorphic phantom was scanned with varying DBI in right, anterior, superior, and inferior directions. Thirty patients undergoing STI were prospectively recruited. Objective metrics, utilizing regions of interest included contrast-to-noise ratio (CNR) at the centrum semiovale, lateral ventricle, and basal ganglia levels, gray and white matter noise at the basal ganglia level, artifact index (AI), and nonuniformity (NU). Two radiation oncologists assessed subjective metrics. In this phantom study, objective measures indicated a degradation in image quality for non-zero DBI. In this patient study, there were significant correlations between the CNR at the centrum semiovale and lateral ventricle levels (rs = - 0.79 and - 0.77, respectively), gray matter noise (rs = 0.52), AI (rs = 0.72), and NU (rs = 0.91) and DBI. However, no significant correlations were observed between the CNR at the basal ganglia level, white matter noise, and subjective metrics and DBI (rs < ± 0.3). Our results demonstrate the effects of DBI on contrast, noise, artifacts in the posterior fossa, and uniformity of CBCT images in STI. Aligning the CBCT isocenter with the brain center can aid in improving image quality.
Asunto(s)
Encéfalo , Tomografía Computarizada de Haz Cónico , Fantasmas de Imagen , Radiocirugia , Humanos , Encéfalo/diagnóstico por imagen , Masculino , Femenino , Persona de Mediana Edad , Neoplasias Encefálicas/diagnóstico por imagen , Neoplasias Encefálicas/radioterapia , Anciano , Relación Señal-Ruido , Procesamiento de Imagen Asistido por Computador , Adulto , ArtefactosRESUMEN
PURPOSE: The geometric distortion related to magnetic resonance (MR) imaging in a diagnostic radiology (MRDR) and radiotherapy (MRRT) setup is evaluated, and the dosimetric impact of MR distortion on fractionated stereotactic radiotherapy (FSRT) in patients with brain metastases is simulated. MATERIALS AND METHODS: An anthropomorphic skull phantom was scanned using a 1.5T MR scanner, and the magnitude of MR distortion was calculated with (MRDR-DC and MRRT-DC) and without (MRDR-nDC and MRRT-nDC) distortion-correction algorithms. Automated noncoplanar volumetric modulated arc therapy (HyperArc, HA; Varian Medical Systems, Palo Alto, CA, USA) plans were generated for 53 patients with 186 brain metastases. The MR distortion at each gross tumor volume (GTV) was calculated using the distance between the center of the GTV and the MR image isocenter (MIC) and the quadratic regression curve derived from the phantom study (MRRT-DC and MRRT-nDC). Subsequently, the radiation isocenter of the HA plans was shifted according to the MR distortion at each GTV (HADC and HAnDC). RESULTS: The median MR distortions were approximately 0.1â¯mm when the distance from the MIC was <â¯30â¯mm, whereas the median distortion varied widely when the distance was >â¯60â¯mm (0.23, 0.47, 0.37, and 0.57â¯mm in MRDR-DC, MRDR-nDC, MRRT-DC, and MRRT-nDC, respectively). The dose to the 98% of the GTV volume (D98%) decreased as the distance from the MIC increased. In the HADC plans, the relative dose difference of D98% was less than 5% when the GTV was located within 70â¯mm from the MIC, whereas the underdose of GTV exceeded 5% when it was 48â¯mm (-26.5% at maximum) away from the MIC in the HAnDC plans. CONCLUSION: Use of a distortion-correction algorithm in the studied MR diagnoses is essential, and the dosimetric impact of MR distortion is not negligible, particularly for tumors located far away from the MIC.
Asunto(s)
Neoplasias Encefálicas , Radiocirugia , Humanos , Planificación de la Radioterapia Asistida por Computador/métodos , Radiocirugia/métodos , Algoritmos , Neoplasias Encefálicas/diagnóstico por imagen , Neoplasias Encefálicas/radioterapia , Neoplasias Encefálicas/secundario , Imagen por Resonancia Magnética/métodos , Dosificación RadioterapéuticaRESUMEN
BACKGROUND: The aim of this study was to evaluate the effectiveness of intensity-modulated radiation therapy in combination with long-term androgen deprivation therapy for high-risk and very high-risk localized prostate cancer while also investigating factors associated with the therapeutic effect. METHODS: Men who fulfilled criteria for the National Comprehensive Cancer Network high-risk or very high-risk localized prostate cancer and were treated with definitive intensity-modulated radiation therapy (74-78 Gy) of the prostate and the seminal vesicle combined with androgen deprivation therapy in our institution from 2007 to 2016 were identified (n = 197). In principle, patients received androgen deprivation therapy for 3-6 months before radiation, concurrently, and for 2 years after completion of intensity-modulated radiation therapy. RESULTS: The median follow-up period was 96 months. The 5-year and 10-year overall survival rates in the overall population were 96.9% and 89.3%, respectively. The 5-year and 10-year cumulative incidence rates of biochemical failure were 2.5% and 16.3% in the high-risk group, and 8.6% and 32.0% in the very high-risk group, respectively, indicating a significant difference between the two groups (P = 0.023). Grade Group 5 and younger age (cutoff: 70 years old) were independent predictors of recurrence (P = 0.016 and 0.017, respectively). Patients exhibiting biochemical failure within <18 months after completion of androgen deprivation therapy displayed an increased risk of cancer-specific mortality (P = 0.039) when contrasted with those who had a longer interval to biochemical failure. CONCLUSIONS: Patients with the National Comprehensive Cancer Network very high-risk prostate cancer, particularly those with Grade Group 5 and younger age, showed worse outcomes following intensity-modulated radiation therapy and long-term androgen deprivation therapy.
Asunto(s)
Neoplasias de la Próstata , Radioterapia de Intensidad Modulada , Masculino , Humanos , Anciano , Neoplasias de la Próstata/tratamiento farmacológico , Neoplasias de la Próstata/radioterapia , Radioterapia de Intensidad Modulada/efectos adversos , Antagonistas de Andrógenos/uso terapéutico , Andrógenos , Antígeno Prostático EspecíficoRESUMEN
To explore predictors of the histopathological response to preoperative chemoradiotherapy (CRT) in patients with pancreatic cancer (PC) using dual-energy computed tomography-reconstructed images. This retrospective study divided 40 patients who had undergone preoperative CRT (50-60 Gy in 25 fractions) followed by surgical resection into two groups: the response group (Grades II, III and IV, evaluated from surgical specimens) and the nonresponse group (Grades Ia and Ib). The computed tomography number [in Hounsfield units (HUs)] and iodine concentration (IC) were measured at the locations of the aorta, PC and pancreatic parenchyma (PP) in the contrast-enhanced 4D dual-energy computed tomography images. Logistic regression analysis was performed to identify predictors of histopathological response. Univariate analysis did not reveal a significant relation between any parameter and patient characteristics or dosimetric parameters of the treatment plan. The HU and IC values in PP and the differences in HU and IC between the PP and PC (ΔHU and ΔIC, respectively) were significant predictors for distinguishing the response (n = 24) and nonresponse (n = 16) groups (P < 0.05). The IC in PP and ΔIC had a higher area under curve values [0.797 (95% confidence interval, 0.659-0.935) and 0.789 (0.650-0.928), respectively] than HU in PP and ΔHU [0.734 (0.580-0.889) and 0.721 (0.562-0.881), respectively]. The IC value could potentially be used for predicting the histopathological response in patients who have undergone preoperative CRT.
Asunto(s)
Yodo , Neoplasias Pancreáticas , Humanos , Estudios Retrospectivos , Medios de Contraste , Tomografía Computarizada por Rayos X/métodos , Neoplasias Pancreáticas/diagnóstico por imagen , Neoplasias Pancreáticas/terapia , Quimioradioterapia/métodos , Neoplasias PancreáticasRESUMEN
This study aimed to compare dosimetric parameters for targets and organs at risk (OARs) between volumetric modulated arc therapy (VMAT) and automated VMAT (HyperArc, HA) plans in stereotactic radiotherapy for patients with cervical metastatic spine tumors. VMAT plans were generated for 11 metastases using the simultaneous integrated boost technique to deliver 35 to 40 and 20 to 25 Gy for high dose and elective dose planning target volume (PTVHD and PTVED), respectively. The HA plans were retrospectively generated using 1 coplanar and 2 noncoplanar arcs. Subsequently, the doses to the targets and OARs were compared. The HA plans provided significantly higher (p < 0.05) Dmin (77.4 ± 13.1%), D99% (89.3 ± 8.9%), and D98% (92.5 ± 7.7%) for gross tumor volume (GTV) than those of the VMAT plans (73.4 ± 12.2%, 84.2 ± 9.6 and 87.3 ± 8.8% for Dmin, D99% and D98%, respectively). In addition, D99% and D98% for PTVHD were significantly higher in the HA plans, whereas dosimetric parameters were comparable between the HA and VMAT plans for PTVED. The Dmax values for the brachial plexus, esophagus, and spinal cord were comparable, and no significant difference was observed in the Dmean for the larynx, pharyngeal constrictor, thyroid, parotid grand (left and right), and Submandibular gland (left and right). The HA plans provided significantly higher target coverage of GTV and PTVHD, with a comparable dose for OARs with VMAT plans. The results of this study may contribute to the improvement of local control in clinical practice.
RESUMEN
BACKGROUND: Data on acute toxicities after stereotactic radiotherapy (SRT) for brain metastases, including multiple and large lesions, are lacking. We aimed to evaluate the incidence and nature of toxicities immediately after SRT using a linear accelerator. METHODS: This retrospective study reviewed the medical records of 315 patients with brain metastases treated with SRT at our institution between May 2019 and February 2022. In total, 439 SRT sessions were performed for 2161 brain metastases. The outcome of interest was immediate side effects (ISEs), defined as new or worsening symptoms occurring during SRT or within 14 days after the end of SRT. RESULTS: Grade ≥ 2 and ≥ 3 ISEs occurred in 16 (3.6%) and 7 (1.6%) cases, respectively. Among 63 treatments for 10 or more lesions (range: 10-40), 1 (1.6%) ISE occurred. Among 22 treatments for lesions with a maximum tumor volume of > 10 cc, 2 (9.1%) ISEs occurred. Grade ≥ 3 ISEs included 1, 4, 1, and 1 cases of grade 3 nausea, grade 3 new-onset partial and generalized seizures, grade 3 obstructive hydrocephalus, and grade 5 intracranial hemorrhage, respectively. ISEs were more common in patients with a larger maximum tumor volume, primary sites other than lung and breast cancer, and pre-treatment neurological symptoms. CONCLUSION: SRT using a linear accelerator for brain metastases, including multiple and large lesions, is safe, with a low incidence of ISEs. Serious complications immediately after SRT are rare but possible; therefore, careful follow-up is necessary after treatment initiation.
Asunto(s)
Neoplasias Encefálicas , Radiocirugia , Humanos , Estudios Retrospectivos , Incidencia , Neoplasias Encefálicas/secundario , Radiocirugia/efectos adversos , Aceleradores de PartículasRESUMEN
To compare the dosimetric parameters of automated noncoplanar volumetric modulated arc therapy plans using single-isocentric (SIC) and multi-isocentric (MIC) techniques for patients with two brain metastases (BMs) in stereotactic irradiation and to evaluate the robustness of rotational errors. The SIC and MIC plans were retrospectively generated (35 Gy/five fractions) for 58 patients. Subsequently, a receiver operating characteristic curve analysis between the tumor surface distance (TSD) and V25Gy was performed to determine the thresholds for the brain tissue. The SIC and MIC plans were recalculated based on the rotational images to evaluate the dosimetric impact of rotational error. The MIC plans showed better brain tissue sparing for TSD > 6.6 cm. The SIC plans provided a significantly better conformity index for TSD ≤ 6.6 cm, while significantly lower gradient index was obtained (3.22 ± 0.56vs. 3.30 ± 0.57, p < 0.05) in the MIC plans with TSD > 6.6 cm. For organs at risk (OARs) (brainstem, chiasm, lens, optic nerves, and retinas), D0.1 cc was significantly lower (p < 0.05) in the MIC plans than in the SIC plans. The prescription dose could be delivered (D99%) to the gross tumor volume (GTV) for patients with TSD ≤ 6.6 cm when the rotational error was < 1°, whereas 31% of the D99% of GTV fell below the prescription dose with TSD > 6.6 cm. MIC plans can be an optimal approach for reducing doses to OARs and providing robustness against rotational errors in BMs with TSD > 6.6 cm.
Asunto(s)
Neoplasias Encefálicas , Radiocirugia , Radioterapia de Intensidad Modulada , Humanos , Dosificación Radioterapéutica , Radioterapia de Intensidad Modulada/métodos , Estudios Retrospectivos , Planificación de la Radioterapia Asistida por Computador/métodos , Neoplasias Encefálicas/radioterapia , Neoplasias Encefálicas/patología , Órganos en Riesgo , Radiocirugia/métodosRESUMEN
BACKGROUND/AIM: Dosimetric parameters in volumetric modulated arc therapy (VMAT), non-coplanar VMAT (NC-VMAT), and automated NC-VMAT (HyperArc, HA) were compared for patients with maxillary sinus carcinoma (MSC). PATIENTS AND METHODS: Twenty HA plans were generated to deliver 70.4, 64, and 46 Gy for planning target volumes with high (PTV1), intermediate (PTV2), and low risk (PTV3), respectively. The VMAT and NC-VMAT plans were retrospectively generated using the same optimized parameters as those used in the HA plans. RESULTS: For PTV1, the three treatment plans provided comparable target coverages. For PTV2, the D95%, D99%, and Dmin in the HA plans (64.7±1.2, 62.7±2.1 and 54.6±6.2 Gy, respectively) were significantly higher (p<0.05) than those in the VMAT plans (64.3±1.7, 61.9±2.4 and 52.9±6.4 Gy, respectively). The NC-VMAT and HA plans provided significantly higher (p<0.05) dosimetric parameters for PTV3 than those in the VMAT plans, and D99% in the HA was significantly higher than that in the NC-VMAT plans (52.5±3.0 vs. 51.8±2.7 Gy, p<0.05). The doses to the brain and brainstem were lowest in the HA plans (p<0.05). Moreover, dosimetric parameters of the contralateral organs (lens, optic nerve, retina, and parotid) were lower in the HA plans than in the VMAT and NC-VMAT plans. CONCLUSION: The HA plans provided the best target coverage and OAR sparing compared with VMAT and NC-VMAT plans for patients with MSC.
Asunto(s)
Carcinoma , Radioterapia de Intensidad Modulada , Humanos , Seno Maxilar , Dosificación Radioterapéutica , Órganos en Riesgo , Estudios Retrospectivos , Planificación de la Radioterapia Asistida por ComputadorRESUMEN
To compare dosimetric parameters for the hippocampus, organs at risk (OARs), and targets of volumetric modulated arc therapy (VMAT), noncoplanar VMAT (NC-VMAT), and HyperArc (HA) plans in patients undergoing postoperative radiotherapy for primary brain tumors. For 20 patients, HA plans were generated to deliver 40.05 to 60 Gy for the planning target volume (PTV). In addition, doses for the hippocampus and OARs were minimized. The VMAT and NC-VMAT plans were retrospectively generated using the same optimization parameters as those in the HA plans. For the hippocampus, the equivalent dose to be administered in 2 Gy fractions (EQD2) was calculated assuming α/ßâ¯=â¯2. Dosimetric parameters for the PTV, hippocampus, and OARs in the VMAT, NC-VMAT, and HA plans were compared. For PTV, the HA plans provided significantly lower Dmax and D1% than the VMAT and NC-VMAT plans (p < 0.05), whereas the D99% and Dmin were significantly higher (p < 0.05). For the contralateral hippocampus, the dosimetric parameters in the HA plans (8.1 ± 9.6, 6.5 ± 7.2, 5.6 ± 5.8, and 4.8 ± 4.7 Gy for D20%, D40%, D60% and D80%, respectively) were significantly smaller (p < 0.05) than those in the VMAT and NC-VMAT plans. Except for the optic chiasm, the Dmax in the HA plans (brainstem, lens, optic nerves, and retinas) was the smallest (p < 0.05). In addition, the doses in the HA plans for the brain and skin were the smallest (p < 0.05) among the 3 plans. HA planning, instead of coplanar and noncoplanar VMAT, significantly reduces the dosage to which the contralateral hippocampus as well as other OARs are exposed without compromising on target coverage.
Asunto(s)
Neoplasias Encefálicas , Radioterapia de Intensidad Modulada , Humanos , Dosificación Radioterapéutica , Reducción Gradual de Medicamentos , Estudios Retrospectivos , Planificación de la Radioterapia Asistida por Computador , Radioterapia de Intensidad Modulada/efectos adversos , Órganos en Riesgo , Neoplasias Encefálicas/radioterapia , Neoplasias Encefálicas/cirugía , HipocampoRESUMEN
BACKGROUND AND PURPOSE: Few reports include volumetric measurements as endpoints after stereotactic radiotherapy (SRT) despite the importance of such measurements. This study aimed to (1) investigate the impact of the volumetric response (specifically, an over 65% and over 90% volume reduction in brain metastases) at 6 months post-SRT on local control and (2) identify the predictive factors for a volumetric response of over 65% and over 90%. MATERIALS AND METHODS: This study included 250 unresected brain metastases (>0.3 cc) treated with SRT. Doses were stratified according to the biological effective dose (BED). The BED was calculated using four models: linear-quadratic (LQ): α/ß = 10; LQ: α/ß = 20; LQ cubic: α/ß = 12; and LQ linear: α/ß = 10. The median prescription dose was 30 Gy/3 fractions (BED20, 45). The median follow-up time after SRT was 18.6 months (range, 6.4-81.8 months). RESULTS: In the multivariate analysis, over 65% volume reduction and over 90% volume reduction were prognostic factors for local control (hazard ratio: 2.370, p = 0.011 and hazard ratio: 3.161, p = 0.014, respectively). A dose of 80% of the gross tumor volume (GTV) D80 > BED20 58 was a predictive factor for over 65% and over 90% volume reductions (odds ratio: 1.975, p = 0.023; odds ratio: 3.204, p < 0.001, respectively). CONCLUSION: Robust volume reduction of brain metastases at 6 months post-SRT can predict local control. GTV D80 in the LQ model: α/ß = 20 may be warranted for good volume reduction.
Asunto(s)
Neoplasias Encefálicas , Radiocirugia , Humanos , Pronóstico , Radiocirugia/efectos adversos , Neoplasias Encefálicas/patología , Modelos de Riesgos Proporcionales , Análisis Multivariante , Estudios Retrospectivos , Dosificación RadioterapéuticaRESUMEN
BACKGROUND: The optimal radiation dose for treating non-metastatic superficial esophageal squamous cell carcinoma is unknown. In this retrospective observational study, we investigated the influence of radiation dose and pretreatment endoscopic prediction of tumor invasion depth on local recurrence after definitive chemoradiotherapy in patients with superficial esophageal squamous cell carcinoma. METHODS: We analyzed 134 patients with clinical Tis-T1N0M0 esophageal squamous cell carcinoma who underwent chemoradiotherapy at our institution between 2006 and 2019. Patients were grouped into standard-dose (50.0-50.4 Gy) and high-dose (60.0 Gy) radiotherapy groups. The outcomes of interest were local recurrence and major local recurrence (endoscopically unresectable local recurrent tumors). Kaplan-Meier analysis and the log-rank test were used with propensity score and inverse probability of treatment weighting. Cox proportional hazards analysis was performed to identify predictors of local recurrence and major local recurrence. RESULTS: The median follow-up times were 52 and 84 months for the standard-dose and high-dose groups, respectively. The adjusted 3-year local recurrence and major local recurrence rates in the standard-dose and high-dose groups were 33.8 and 9.6% (adjusted hazard ratio, 4.00 [95% confidence interval: 1.64-9.73]; adjusted log-rank p = 0.001) and 12.5 and 4.7% (adjusted hazard ratio, 3.13 [95% confidence interval: 0.91-10.81]; adjusted log-rank p = 0.098), respectively. Cox proportional hazards analysis showed that standard-dose radiotherapy and endoscopic findings of deep submucosal invasion are independently associated with local recurrence and major local recurrence. CONCLUSIONS: High-dose radiotherapy is more beneficial for local tumor control than standard-dose radiotherapy in patients with non-metastatic superficial esophageal squamous cell carcinoma. The use of high-dose radiotherapy may merit consideration for tumors with deep submucosal invasion.
Asunto(s)
Quimioradioterapia , Neoplasias Esofágicas/patología , Neoplasias Esofágicas/terapia , Carcinoma de Células Escamosas de Esófago/patología , Carcinoma de Células Escamosas de Esófago/terapia , Recurrencia Local de Neoplasia , Anciano , Femenino , Estudios de Seguimiento , Humanos , Estimación de Kaplan-Meier , Masculino , Persona de Mediana Edad , Invasividad Neoplásica , Estadificación de Neoplasias , Puntaje de Propensión , Modelos de Riesgos Proporcionales , Dosificación Radioterapéutica , Estudios RetrospectivosRESUMEN
PURPOSE: This study introduced an A-mode portable ultrasound bladder scanner, the Lilium® α-200 (here after Lilium; Lilium Otsuka, Kanagawa, Japan), for the treatment of prostate cancer patients with hypofractionated volumetric modulated arc therapy to improve the reproducibility of bladder volume (BV). MATERIALS AND METHODS: Thirty patients were advised to maintain full BV prior to computed tomography (CT) simulation and daily treatment. Among these, the BV of 15 patients was measured using Lilium until a BV of 80% in the simulation was achieved (with the Lilium group). Daily cone-beam CT (CBCT) was performed for treatment. The correlation between BV measured by CBCT and Lilium was assessed. The differences in the BV and dosimetric parameters of the bladder in the CBCT versus planning CT were compared between the groups with and without Lilium. RESULTS: There was a significantly strong relationship (r = 0.796, p < 0.05) between the BVs measured using CBCT and Lilium. The relative BV ratios to simulation CT < 0.5 and > 2 were observed in 10.3% and 12.7%, respectively, of treatment sessions without Lilium group, while these ratios were 1% and 2.8%, respectively, in the Lilium group. The mean absolute difference in the range of V30Gy to V40Gy without Lilium sessions was significantly larger (p < 0.05) than that in the Lilium group. CONCLUSION: The use of the A-mode portable ultrasound bladder scanner significantly improved the reproducibility of the BV, resulting in few variations in the dosimetric parameters for the bladder.
Asunto(s)
Neoplasias de la Próstata , Radioterapia de Intensidad Modulada , Tomografía Computarizada de Haz Cónico/métodos , Humanos , Masculino , Neoplasias de la Próstata/diagnóstico por imagen , Neoplasias de la Próstata/radioterapia , Planificación de la Radioterapia Asistida por Computador , Radioterapia de Intensidad Modulada/métodos , Reproducibilidad de los Resultados , Ultrasonografía , Vejiga Urinaria/diagnóstico por imagenRESUMEN
PURPOSE: To compare the intrafractional motion error (IME) during stereotactic irradiation (STI) in patients with brain metastases immobilized using open- (Encompass) and full-face (DSPS) clamshell-style immobilization devices. METHODS: Encompass (38 patients) and DSPS (38 patients) were used for patient immobilization, and HyperArc plans with three to four non-coplanar beams were generated to deliver 25 to 35 Gy in three to five fractions. Cone-beam computed tomography (CBCT) was performed on patients before and after the treatment. Moreover, the difference in patient position between the two CBCT images was considered as the IME. The margins to compensate for IME were calculated using the van Herk margin formula. RESULTS: For Encompass, the mean values of IME in the translational setup were 0.1, 0.2, and 0.0 mm in the anterior-posterior, superior-inferior, and left-right directions, respectively, and the mean values of IME about rotational axes were -0.1, 0.0, and 0.0° for the Pitch, Roll, and Yaw rotations, respectively. For DSPS, the mean values of IME in the translational setup were 0.2, 0.2, and 0.0 mm in the anterior-posterior, superior-inferior, and left-right directions, respectively, and the mean values of IME about rotational axes were -0.1, -0.1, and 0.0° for the Pitch, Roll, and Yaw rotations, respectively. No statistically significant difference was observed between the IME of the two immobilization systems except in the anterior-posterior direction (p = 0.02). Moreover, no statistically significant correlation was observed between three-dimensional IME and treatment time. The margin compensation for IME was less than 1 mm for both immobilization devices. CONCLUSIONS: The IME during STI using open- and full-face clamshell-style immobilization devices is approximately equal considering the adequate accuracy in patient positioning.
Asunto(s)
Neoplasias Encefálicas , Radiocirugia , Neoplasias Encefálicas/cirugía , Tomografía Computarizada de Haz Cónico/métodos , Humanos , Inmovilización , Posicionamiento del Paciente , Radiocirugia/métodos , Planificación de la Radioterapia Asistida por Computador/métodos , Errores de Configuración en Radioterapia/prevención & controlRESUMEN
Introduction: Several studies have reported the relation between the imaging dose and secondary cancer risk and have emphasized the need to minimize the additional imaging dose as low as reasonably achievable. The iterative cone-beam computed tomography (iCBCT) algorithm can improve the image quality by utilizing scatter correction and statistical reconstruction. We investigate the use of a novel iCBCT reconstruction algorithm to reduce the patient dose while maintaining low-contrast detectability and registration accuracy. Methods: Catphan and anthropomorphic phantoms were analyzed. All CBCT images were acquired with varying dose levels and reconstructed with a Feldkamp-Davis-Kress algorithm-based CBCT (FDK-CBCT) and iCBCT. The low-contrast detectability was subjectively assessed using a 9-point scale by 4 reviewers and objectively assessed using structure similarity index (SSIM). The soft tissue-based registration error was analyzed for each dose level and reconstruction technique. Results: The results of subjective low-contrast detectability found that the iCBCT acquired at two-thirds of a dose was superior to the FDK-CBCT acquired at a full dose (6.4 vs 5.4). Relative to FDK-CBCT acquired at full dose, SSIM was higher for iCBCT acquired at one-sixth dose in head and head and neck region while equivalent with iCBCT acquired at two-thirds dose in pelvis region. The soft tissue-based registration was 2.2 and 0.6â mm for FDK-CBCT and iCBCT, respectively. Conclusion: Use of iCBCT reconstruction algorithm can generally reduce the patient dose by approximately two-thirds compared to conventional reconstruction methods while maintaining low-contrast detectability and accuracy of registration.
Asunto(s)
Tomografía Computarizada de Haz Cónico/métodos , Procesamiento de Imagen Asistido por Computador/métodos , Dosificación Radioterapéutica , Planificación de la Radioterapia Asistida por Computador/métodos , Radioterapia Guiada por Imagen/métodos , Antropometría , Biomarcadores , Medios de Contraste , Humanos , Pelvis/diagnóstico por imagen , Fantasmas de Imagen , Radioterapia Guiada por Imagen/normas , Relación Señal-RuidoRESUMEN
Previous studies have reported conflicting results for the effect of overall treatment time with stereotactic body radiotherapy on tumor control in early-stage non-small-cell lung cancer. To examine this effect, we conducted a propensity score-weighted, retrospective, observational study at a single institution. We analyzed the data of 200 patients with early-stage non-small-cell lung cancer who underwent stereotactic body radiotherapy (48 Gy in 4 fractions) at our institution between January 2007 and October 2013. Patients were grouped into consecutive (overall treatment time = 4-5 days, n = 116) or non-consecutive treatment groups (overall treatment time = 6-10 days, n = 84). The outcomes of interest were local control and overall survival. The Cox regression model was used with propensity score and inverse probability of treatment weighting. The median overall treatment times in the consecutive and non-consecutive groups were 4 and 6 days, respectively. The 5-year local control and overall survival rates in the consecutive vs. the non-consecutive group were 86.3 vs. 77.2% and 55.5 vs. 51.8%, respectively. After propensity score weighting, consecutive stereotactic body radiotherapy was associated with positive local control (adjusted hazard ratio 0.30, 95% confidence interval 0.14-0.65; p = 0.002) and overall survival (adjusted hazard ratio 0.56, 95% confidence interval 0.34-0.91; p = 0.019) benefits. The prolonged overall treatment time of stereotactic body radiotherapy treatment negatively affected the outcomes of patients with early-stage non-small-cell lung cancer. To our knowledge, this is the first study to show that in patients with early-stage non-small-cell lung cancer treated with the same dose-fractionation regimen, consecutive stereotactic body radiotherapy has a more beneficial effect on tumor control than non-consecutive stereotactic body radiotherapy.