Stereotactic radiosurgery for prostate cancer spine metastases: local control and fracture risk using a simultaneous integrated boost approach.

OBJECTIVE: Variation exists in approaches to delivery of spine stereotactic radiosurgery (SSRS). Here, the authors describe outcomes following single-fraction SSRS performed using a simultaneous integrated boost for the treatment of prostate cancer spine metastases. METHODS: Health records of patients with prostate cancer spine metastases treated with single-fraction SSRS at the authors' institution were reviewed. Treatment was uniform, with 16 Gy to the clinical tumor volume and 18 Gy to the gross tumor volume. The primary endpoint was local recurrence, with secondary endpoints including vertebral fracture and overall survival. Univariate and multivariate competing risk regression models made using the Fine and Gray method were used to identify factors predictive of local recurrence, considering death to be a competing event for local recurrence. RESULTS: A total of 87 targets involving 108 vertebrae in 68 patients were included, with a median follow-up of 22.5 months per treated target. The 1-, 2-, and 4-year cumulative incidence rates of local failure for all targets were 4.6%, 8.4%, and 19%, respectively. The presence of epidural disease (subdistribution hazard ratio [sHR] 5.43, p = 0.04) and SSRS as reirradiation (sHR 16.5, p = 0.02) emerged as significant predictors of local failure in a multivariate model. Hormone sensitivity did not predict local control. Vertebral fracture incidence rates leading to symptoms or requiring intervention at 1, 2, and 4 years were 1.1%, 3.7%, and 8.4%, respectively. In an exploratory analysis of patterns of failure, 3 (25%) failures occurred in the epidural space and only 1 (8%) occurred clearly in the clinical tumor volume. There were several lesions for which the precise location of failure with regard to target volumes was unclear. CONCLUSIONS: High rates of local control were observed, particularly for radiotherapy-naïve lesions without epidural disease. Hormone sensitivity was not predictive of local control in this cohort and fracture risk was low. Further research is needed to better predict which patients are at high risk of recurrence and who might benefit from treatment escalation.

Progression rates of medulla oblongata infarcts in clinical follow-up: A retrospective study.

OBJECTIVE: To determine clinical progression rates in patients with medulla oblongata infarction (MOI). MATERIALS AND METHODS: The data of patients diagnosed with MOI were analysed retrospectively. Dermographic characteristics of the patients; Age, gender, history and stroke etiology were evaluated. Radiological imagings were reviewed retrospectively. Intensive care unit (ICU) requirement, number of intubation days, failed extubation and death rates, good clinical outcome at discharge and 3 months [modified Rankin Scale (mRS 0-2)] and poor clinical outcome (mRS 3-6) rates were evaluated. In addition, the clinical results of patients with medial medullary infarction (MMI) and lateral medullary infarction (LMI) were compared. RESULTS: 33 patients were included in the study, 22 (66.7 %) were male. The mean age of the patients was 72.0 (43.0-85.0). The characteristics of the patients (dermographic features, comorbidities, clinical symptoms, infarct localization, etc.) were evaluated. The results of MMI and LMI patients were compared. The intubation rate was 4 (44.4 %) in the MME group, while it was 8 (33.3 %) in the LME group. There was no statistically significant difference between the two groups in terms of failed extubation, tracheostomy, hospitalization and mortality rates. However, while discharge mRS was statistically significant between the two groups, the mRS at 3 months was not statistically significant. Twelve (36.4 %) of all patients were intubated due to severe clinical progression. In the clinical follow-up, 6 (50.0 %) of the intubated patients died, 3rd month mRS of 6 (50.0 %) patients who survived was 5. In all patients 3-month good clinical outcome rate was % 48,5. CONCLUSION: It should not be forgotten that life-threatening clinical progressions may develop at a considerable rate during the early treatment process of patients diagnosed with MOI.

Adverse events of after-loading high dose rate brachytherapy reported to the United States Food and Drug Administration (FDA).

PURPOSE: To provide an assessment of safety regarding high-dose-rate after-loading brachytherapy (HDR-BT) based on adverse events reported to the OpenFDA, an open access database maintained by the United States Food and Drug Administration (FDA). METHODS: OpenFDA was queried for HDR-BT events between 1993 and 2019. A brachytherapist categorized adverse events (AEs) based on disease site, applicator, manufacturer, event type, dosimetry impact, and outcomes. Important findings are summarized. RESULTS: 372 AEs were reported between 1993 and 2019, with a downwards trend after 2014. Nearly half of AEs (48.9%) were caused by a device malfunction, and 27.4% resulted in patient injury. Breast (49.2%) and Gyn (23.7%) were the most common disease sites of AEs. Applicator breaks cause the majority of AEs (64.2%) and breast balloon implants were the most common applicator to malfunction (38.7%). User error contributed to only 16.7% of events. 11.0% of events required repair of the afterloader. There were no reported staff injuries or patient deaths from an AE, however 24.7% of patients received resultant incorrect radiation dose, 16.4% required additional procedures to rectify the AE, and 3.0% resulted in unintended radiation to staff. CONCLUSION: The OpenFDA database has shown a decreasing trend in AEs since 2014 for HDR-BT. Most AEs are not caused by user error and do not cause patient injury or incorrect radiation dose. Investigation into methods to prevent failures and improve applicators such as the breast balloon could improve safety. These results support the continued use of HDR-BT as a safe treatment modality for cancer.

Scatter imaging during lung stereotactic body radiation therapy characterized with phantom studies.

By collecting photons scattered out of the therapy beam, scatter imaging creates images of the treated volume. Two phantoms were used to assess the possible application of scatter imaging for markerless tracking of lung tumors during stereotactic body radiation therapy (SBRT) treatment. A scatter-imaging camera was assembled with a CsI flat-panel detector and a 5 mm diameter pinhole collimator. Scatter images were collected during the irradiation of phantoms with megavoltage photons. To assess scatter image quality, spherical phantom lung tumors of 2.1-2.8 cm diameters were placed inside a static, anthropomorphic phantom. To show the efficacy of the technique with a moving target (3 cm diameter), the position of a simulated tumor was tracked in scatter images during sinusoidal motion (15 mm amplitude, 0.25 Hz frequency) in a dynamic lung phantom in open-field, dynamic conformal arc (DCA), and volumetric modulated arc therapy (VMAT) deliveries. Anatomical features are identifiable on static phantom scatter images collected with 10 MU of delivered dose (2.1 cm diameter lung tumor contrast-to-noise ratio of 4.4). The contrast-to-noise ratio increases with tumor size and delivered dose. During dynamic motion, the position of the 3.0 cm diameter lung tumor was identified with a root-mean-square error of 0.8, 1.2, and 2.9 mm for open field (0.3 s frame integration), DCA (0.5 s), and VMAT (0.5 s), respectively. Based on phantom studies, scatter imaging is a potential technique for markerless lung tumor tracking during SBRT without additional imaging dose. Quality scatter images may be collected at low, clinically relevant doses (10 MU). Scatter images are capable of sub-millimeter tracking precision, but modulation decreases accuracy.

The role of brachytherapy in the management of brain metastases: a systematic review.

PURPOSE: Brain metastases have a highly variable prognosis depending on the primary tumor and associated prognostic factors. Standard of care for patients with these tumors includes craniotomy, stereotactic radiosurgery (SRS), or whole brain radiotherapy (WBRT) for patients with brain metastases. Brachytherapy shows great promise as a therapy for brain metastases, but its role has not been sufficiently explored in the current literature. MATERIAL AND METHODS: The PubMed, Cochrane, and Scopus databases were searched using a combination of search terms and synonyms for brachytherapy, brain neoplasms, and brain metastases, for articles published between January 1st, 1990 and January 1st, 2018. Of the 596 articles initially identified, 37 met the inclusion criteria, of which 14 were review articles, while the remaining 23 papers with detailing individual studies were fully analyzed. RESULTS: Most data focused on 125I and suggested that it offers rates of local control and overall survival comparable to standard of care modalities such as SRS. However, radiation necrosis and regional recurrence were often high with this isotope. Studies using photon radiosurgery modality of brachytherapy have also been completed, resulting superior regional control as compared to SRS, but worse local control and higher rates of radiation necrosis than 125I. More recently, studies using the 131Cs for brachytherapy offered similar local control and survival benefits to 125I, with low rates of radiation necrosis. CONCLUSIONS: For a variety of reasons including absence of physician expertise in brachytherapy, lack of published data on treatment outcomes, and rates of radiation necrosis, brachytherapy is not presently a part of standard paradigm for brain metastases. However, our review indicates brachytherapy as a modality that offers excellent local control and quality of life, and suggested that its use should be further studied.

Brachytherapy application with in situ dose painting administered by gold nanoparticle eluters.

PURPOSE: Recent studies show promise that administering gold nanoparticles (GNP) to tumor cells during brachytherapy could significantly enhance radiation damage to the tumor. A new strategy proposed for sustained administration of the GNP in prostate tumors is to load them into routinely used brachytherapy spacers for customizable in situ release after implantation. This in silico study investigated the intratumor biodistribution and corresponding dose enhancement over time due to GNP released from such GNP-loaded brachytherapy spacers (GBS). METHOD AND MATERIALS: An experimentally determined intratumoral diffusion coefficient (D) for 10-nm nanoparticles was used to estimate D for other sizes by using the Stokes-Einstein equation. GNP concentration profiles, obtained using D, were then used to calculate the corresponding dose enhancement factor (DEF) for each tumor voxel, using dose painting-by-numbers approach, for times relevant to the considered brachytherapy sources' lifetimes. The investigation was carried out as a function of GNP size for the clinically applicable low-dose-rate brachytherapy sources iodine-125 (I-125), palladium-103 (Pd-103), and cesium-131 (Cs-131). RESULTS: Results showed that dose enhancement to tumor voxels and subvolumes during brachytherapy can be customized by varying the size of GNP released or eluted from the GBS. For example, using a concentration of 7 mg/g GNP, significant DEF (>20%) could be achieved 5 mm from a GBS after 5, 12, 25, 46, 72, 120, and 195 days, respectively, for GNP sizes of 2, 5, 10, 20, 30, and 50 nm and for 80 nm when treating with I-125. CONCLUSIONS: Analyses showed that using Cs-131 provides the highest dose enhancement to tumor voxels. However, given its relatively longer half-life, I-125 presents the most flexibility for customizing the dose enhancement as a function of GNP size. These findings provide a useful reference for further work toward development of potential new brachytherapy application with in situ dose painting administered via gold nanoparticle eluters for prostate cancer.

New potential for enhancing concomitant chemoradiotherapy with FDA approved concentrations of cisplatin via the photoelectric effect.

We predict, for the first time, that by using United States Food and Drug Administration approved concentrations of cisplatin, major radiosensitization may be achieved via photoelectric mechanism during concomitant chemoradiotherapy (CCRT). Our analytical calculations estimate that radiotherapy (RT) dose to cancer cells may be enhanced via this mechanism by over 100% during CCRT. The results proffer new potential for significantly enhancing CCRT via an emerging clinical scenario, where the cisplatin is released in-situ from RT biomaterials loaded with cisplatin nanoparticles.