This study aims at evaluating the symptom response, response duration, and toxicity of single dose palliative liver radiotherapy (Rt) for symptomatic Hcc patients. We reviewed unresectable Hcc patients treated with palliative Rt in our institution. eligible patients were unsuitable or refractory to transarterial chemoembolization (TACE) and stereotactic body radiotherapy (SBRT), with an index symptom of pain or abdominal discomfort. the primary outcome was the percentage of patients with clinical improvement of index symptom at 1 month. Secondary outcomes were response duration, toxicities, alpha-feto protein (AFP) response, and radiological response. Fifty-two patients were included in the study. The index symptom was pain in 34 patients (65.4%), and abdominal discomfort (34.6%) in 18 patients. At 1 month, 51.9% of patients had improvement of symptoms. Median time to symptom progression was 89 days (range: 12-392 days). Treatment was well tolerated with only 2 patients (3.8%) developing grade 3 GI toxicities. AFP response, radiological response rate, and disease control rate at 3 months were 48.6%, 15.1%, and 54.5% respectively. Half of the patients had improvement of index symptoms after receiving palliative liver RT with median response duration of 3 months. The treatment was well tolerated with minimal toxicities.Hepatocellular carcinoma (HCC) is the leading cause of global cancer death 1 . Surgical interventions provide the only chance of cure, yet majority of patients present with advanced disease and are treated with trans-arterial chemoembolization (TACE), targeted therapy, or best supportive care (BSC).Conformal high dose radiotherapy (RT) or stereotactic body radiotherapy (SBRT) has emerged as a promising local therapy in treating unresectable HCC. Multiple studies demonstrated the tumor control at 1 year and 2 year in majority of patients 2-4 . Yet, because of the extensive liver involvement with cancer, borderline liver function, and/or presence of extra-hepatic metastases, many patients are not suitable for high dose radiation. The tolerance of whole liver to radiation is low 5 .Patients who present in advanced stage often experience symptoms of pain or abdominal discomfort at some point of their illnesses 6 . Effective palliation of hepatic pain is challenging. To date, there is limited research regarding palliative radiotherapy (RT) specifically in the HCC population. In the early studies of whole-liver RT in patients mainly with liver metastases at doses ranging from 20-30 Gy, benefit of symptom palliation was observed in 49-95% of patients with limited toxicities 7-14 . Until recently, in a prospective phase II trial of 41 patients with HCC and liver metastases, the use of 8 Gy in single fraction to the whole liver resulted in a clinically meaningful improvement in average index symptom intensity in 48% of patients one month following RT. Benefits were only observed in patients with pain and abdominal discomfort. Treatment was well tolerated with only one patient developed grade 3 toxicity 15 . T...

Treating lung tumors with CyberKnife through continuous tracking of the vertebrae should not be attempted without effective means to reduce the amplitude and variability of target motion because temporal dose variations owing to the intrafractional target motion can be significant.

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In radiosurgery (SRS), the geometric uncertainties of machine-related delivery including image-guidance and hence the planning target volume (PTV) are often evaluated by the end-to-end gamma (γ) comparison that carries no information about the clinical relevance of deviations of individual SRS plans during delivery quality assurance (DQA). A proof-of-concept method was proposed to derive the PTV against both the plan- and the machine-specific delivery errors directly from the clinically relevant dose-volume histograms (DVHs) using measured-guided dose reconstruction (MGDR) during DQA. A liquid-filled detector array and a rotating phantom were used to measure sixteen arc-based radiosurgery treatments with 1 and 2 mm gross tumor volume (GTV)-to-PTV margins, producing MGDR-3D dose distribution on both the phantom and the patient CT for γ index and clinical DVH evaluations, respectively. The PTV was considered optimal when the MGDR showed the desired prescription dose coverage (V pres ) of the GTV (100% in this study). Associations of the binary V pres outcomes (<or  =100%) of the GTV with the acceptance level of percent γ pass rate (γPR%) at 90 versus 95% were assessed. Further receiver operator characteristic (ROC) analysis was performed to assess the distance-to-agreement (DTA) and local dose difference (ΔD) criteria that may be suitable for treatment acceptance. From the MGDR, 100% GTV V pres was achieved in 68.8% and 100% of plans with 1 and 2 mm PTV, respectively. V pres outcomes were neither associated with γPR% at 1–2 mm DTA and 1%–3% ΔD nor the acceptance level for MGDR in the patient CT. ROC analysis shows statistically significant AUC values from 0.78–0.84 and 0.79–0.80 for MGDR phantom and patient doses, respectively. DQA by MGDR-DVH objectives offers the unique opportunity of direct assessment of the dose delivery accuracy and hence the optimal PTV without subject to the statistical correlation between γPR% and clinical metrics. Based on multi-criteria DVH objectives, clinical decision can be instantly made to adjust the treatment plan prescription.

Introduction: To investigate the inter-observer and inter-modality variabilities of two imaging guided equipments-cone-beam computed tomography (CBCT) and ultrasound (US) in kidney stereotactic body radiotherapy. Methods: A renal metastasis case implanted with three gold anchor fiducial markers was firstly scanned by US to acquire a 3-dimension US image and followed by 4-dimension CBCT in every fraction. Seven observers retrospectively registered the pre-treatment images with the corresponding reference images based on the gold markers. Registration uncertainty of the observers between two imaging modalities was evaluated. Results: The uncertainties over whole treatment course in CBCT were 0.88 mm, 1.94 mm and 0.86 mm in lateral, longitudinal and vertical directions respectively; while 0.8 mm, 0.97 mm and 1.36 mm were found in US.