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The purpose of the study was to quantify local setup errors and evaluate the planning target volume (PTV) margins for sub-regions in cone-beam computed tomography (CBCT)-guided post-mastectomy radiation therapy (PMRT). The local setup errors of 20 patients undergoing CBCT-guided PMRT were analysed retrospectively. Image registration between CBCT and planning CT was performed using four sub-regions of interest (ROIs): the supraclavicular area (SROI), ipsilateral chest wall region (CROI), ipsilateral chest wall plus supraclavicular region (SROI + CROI) and vertebral region (TROI). Bland–Altman analysis, correlation, local setup errors and PTV margins among these ROIs were evaluated. There was no significant consistency or correlation for registration results between the TROI and the CROI or SROI regions on any translational axis. When using the SROI + CROI as the ROI, the systematic error (Σ) and random error (σ) of the local setup errors for the CROI region were 1.81, 1.19 and 1.76 mm and 1.84, 2.64 and 3.00 mm along the medial–lateral (ML), superior–inferior (SI) and anterior–posterior (AP) directions, respectively. The PTV margins for the CROI region were 5.80, 4.82 and 6.50 mm. The Σ and σ of the local setup errors for the SROI region were 1.29, 1.15 and 0.77 mm and 1.96, 2.65 and 2.2 mm, respectively, and the PTV margins were 4.59, 4.73 and 3.47 mm. Large setup errors and local setup errors occur in PMRT. The vertebral body should not be a position surrogate for the supraclavicular region or chest wall. To compensate for the local setup errors, different PTV margins are required, even with CBCT guidance.

BACKGROUND The aim of this study is to assess the effect of home enteral nutrition (HEN) on the myelosuppression of patients with nasopharyngeal cancer (NPC) during the course of concurrent chemoradiotherapy (CCRT). METHODS A total of 18 outpatients with NPC administered oral nutritional supplementation intervention at home during the course of CCRT were designated as the HEN group, whereas 36 patients with NPC who had previously completed CCRT were retrospectively included as the control group. Patient Generated Subjective Global Assessment, body mass index (BMI), and blood test were evaluated prior to CCRT. During the course of CCRT, blood test was assessed every 2 weeks. RESULTS In male patients, hemoglobin (HB) and red blood cell were decreased (P

BackgroundTo develop a low-dose cone beam CT (LD-CBCT) reconstruction method named simultaneous algebraic reconstruction technique and dual-dictionary learning (SART-DDL) joint algorithm for image guided radiation therapy (IGRT) and evaluate its imaging quality and clinical application ability.MethodsIn this retrospective study, 62 CBCT image sets from February 2018 to July 2018 at west china hospital were randomly collected from 42 head and neck patients (mean [standard deviation] age, 49.7 [11.4] years, 12 females and 30 males). All image sets were retrospectively reconstructed by SART-DDL (resultant D-CBCT image sets) with 18% less clinical raw projections. Reconstruction quality was evaluated by quantitative parameters compared with SART and Total Variation minimization (SART-TV) joint reconstruction algorithm with pairedttest. Five-grade subjective grading evaluations were done by two oncologists in a blind manner compared with clinically used Feldkamp-Davis-Kress algorithm CBCT images (resultant F-CBCT image sets) and the grading results were compared by paired Wilcoxon rank test. Registration results between D-CBCT and F-CBCT were compared. D-CBCT image geometry fidelity was tested.ResultsThe mean peak signal to noise ratio of D-CBCT was 1.7 dB higher than SART-TV reconstructions (P P > .05). In clinical registration, the maximum translational and rotational difference was 1.8 mm and 1.7 degree respectively. The horizontal, vertical and sagittal geometry fidelity of D-CBCT were acceptable.ConclusionsThe image quality, geometry fidelity and clinical application ability of D-CBCT are comparable to that of the F-CBCT for head-and-neck patients with 18% less projections by SART-DDL.

Purpose To study the inter- and intrafraction tumor reproducibility with active breath control (ABC) utilizing cone-beam computed tomography (CBCT), and compare validity of registration with two different regions of interest (ROI). Methods and materials Thirty-one lung tumors in 19 patients received conventional or stereotactic body radiotherapy with ABC. During each treatment, patients had three CBCT scanned before and after online position correction and after treatment. These CBCT images were aligned to the planning CT using the gray scale registration of tumor and bony registration of the thorax, and tumor position uncertainties were then determined. Results The interfraction systematic and random translation errors in the left–right (LR), superior–inferior (SI) and anterior–posterior (AP) directions were 3.6, 4.8, and 2.9 mm; 2.5, 4.5, and 3.5 mm, respectively, with gray scale alignment; 1.9, 4.3, 2.0 mm and 2.5, 4.4, 2.9 mm, respectively, with bony alignment. The interfraction systematic and random rotation errors with gray scale and bony alignment groups ranged from 1.4° to 3.0° and 0.8° to 2.3°, respectively. The intrafraction systematic and random errors with gray scale registration in LR, SI, AP directions were 0.9, 2.0, 1.8 mm and 1.5, 1.7, 2.9 mm, respectively, for translation; 1.5°, 0.9°, 1.0° and 1.2°, 2.2°, 1.8°, respectively, for rotation. The translational errors in SI direction with bony alignment were significantly larger than that of gray scale ( p Conclusions With CBCT guided online correction the interfraction positioning errors can be markedly reduced. The intrafraction errors were not diminished by the use of ABC. Rotation errors were not very remarkable both inter- and intrafraction. Gray scale alignment of tumor may provide a better registration in SI direction.

Objective: To analyse which local set-up errors can be covered by a 5-mm margin for cone beam computed tomography (CBCT)-guided radiotherapy in nasopharyngeal carcinoma (NPC). Methods: 11 regions of interest (ROIs) were registered for 24 NPC patients, with a total of 323 CBCT scans. According to the registration results, clinical target volume–planning target volume (CTV–PTV)/organs at risk-planning risk volume (OAR-PRV) margin analysis; Pearson correlation analysis; Bland–Altman plots; and a receiver operating characteristic (ROC) analysis were used to investigate which local set-up errors of substructure can be represented by the PTVROI. Results: The clinical target volume-PTV/OAR-planning risk volume margins were less than 5 mm for C1ROI-C4ROI, mandible (MROI), and sphenoid sinus (SROI) with respect to PTVROI. C1ROI-C4ROI, MROI, and SROI exhibited significant correlations and consistencies in the mediolateral, superior–inferior, and anteroposterior (AP) directions and significant receiver operating characteristic analysis results in the anteroposterior direction. Conclusion: Only the upper local set-up error of C1ROI-C4ROI, MROI, and SROI can be covered by a 5-mm margin for CBCT-guided NPC radiotherapy with a large ROI. Using these ROIs as an integral reference ROI is better than individual bony landmark. Advances in knowledge: This report is helpful to CBCT registration for NPC radiotherapy in clinical practice.

Background and purpose Online adaptive correction in image-guided intensity-modulated radiotherapy appeared to be a promising approach for precision radiation treatment in head and neck tumors. This protocol was designed to evaluate the clinical feasibility and effect of online cone beam computed tomography (CBCT) guidance in IMRT of nasopharyngeal cancer (NPC). Methods and materials The Elekta Synergy system, which integrates an X-ray volumetric imager (XVI), was used to deliver radiation treatment for 22 cases of NPC. The acquired CBCT was registered to the planning CT for online and offline analysis. The systematic and random setup errors, as well as planning target volume (PTV) margin, were calculated at different correction threshold levels. The impact of online setup correction on dosimetry was evaluated by simulation of pre-correction errors. Results The correction-of-setup-errors frequencies for 1, 2 and 3mm thresholds were 41.3–53.9%, 12.7–21.2% and 6.3–10.3%, respectively. Online correction was effective at the 2mm threshold level for all three axes. The pre-correction systematic errors for the whole group ranged 1.1–1.3mm, and the random errors were also 1.1–1.3mm. After online correction, the systematic and random errors ranged 0.4–0.5mm and 0.7–0.8mm, respectively, in the three directions. The PTV margins for the pre-correction, pretreatment and post-treatment positions were 3.5–4.2mm, 1.6–1.8mm and 2.5–3.2mm, respectively, in three directions. Analysis of hypothetical dosimetric change due to a translational isocenter shift of 3mm showed that if no correction was applied, the mean maximum dose to both the brain stem and spinal cord would be increased by 10Gy, the mean dose to the left and right parotids would be increased by 7.8 and 8.5Gy, respectively, and the dose to target volumes would be decreased: 4Gy for 95% GTV and 5.6Gy for 95% CTV 60. Conclusions CBCT-based online correction increased the accuracy of IMRT for NPC and reduced irradiated margins, by decreasing both the systematic and random errors. Online CBCT correction reduces the radiation dose to normal tissue and creates room for further dose escalation of tumors.

Background To analyze the feasibility of active breath control (ABC), the lung tumor reproducibility and the rationale for single-breath-hold cone beam CT (CBCT)-guided hypofraction radiotherapy. Methods Single-breath-hold CBCT images were acquired using ABC in a cohort of 83 lung cancer patients (95 tumors) treated with hypofraction radiotherapy. For all alignments between the reference CT and CBCT images (including the pre-correction, post-correction and post-treatment CBCT images), the tumor reproducibility was evaluated via online manual alignment of the tumors, and the vertebral bone uncertainties were evaluated via offline manual alignment of the vertebral bones. The difference between the tumor reproducibility and the vertebral bone uncertainty represents the change in the tumor position relative to the vertebral bone. The relative tumor positions along the coronal, sagittal and transverse axes were measured based on the reference CT image. The correlations between the vertebral bone uncertainty, the relative tumor position, the total treatment time and the tumor reproducibility were evaluated using the Pearson correlations. Results Pre-correction, the systematic/random errors of tumor reproducibility were 4.5/2.6 (medial-lateral, ML), 5.1/4.8 (cranial-caudal, CC) and 4.0/3.6 mm (anterior-posterior, AP). These errors were significantly decreased to within 3 mm, both post-correction and post-treatment. The corresponding PTV margins were 4.7 (ML), 7.4 (CC) and 5.4 (AP) mm. The changes in the tumor position relative to the vertebral bone displayed systematic/random errors of 2.2/2.0 (ML), 4.1/4.4 (CC) and 3.1/3.3 (AP) mm. The uncertainty of the vertebral bone significantly correlated to the reproducibility of the tumor position (P 0.05). Conclusions Using ABC for single-breath-hold CBCT guidance is an effective method to reduce the PTV margin of hypofraction radiotherapy for lung cancer. Using ABC, the tumor position was significantly altered relative to the vertebral position. The reproducibility of the tumor position was affected by the vertebral bone but not by the relative tumor position or the total treatment time.

Background and purpose To evaluate the feasibility and validity of cone beam computed tomography (CBCT) and active breath control (ABC) by long breath-holding in hypofraction radiotherapy of liver tumor. Methods and materials Twenty-four patients received hypofraction radiotherapy of liver tumor with long breath-holding at end-inhale; four prescriptions were used: 6Gy×7 ( n =8), 10Gy×4 ( n =7), 5Gy×9 ( n =6), 4Gy×10 ( n =3). For each fraction, all patients received pre-correction CBCT scans with ABC, some patients received post-correction and post-treatment CBCT. The interfraction and intrafraction liver positioning errors on medial–lateral (ML), cranial–caudal (CC) and anterior–posterior (AP) directions were obtained. The theoretic margin from clinical target volume (CTV) to planning target volume (PTV) was calculated based on post-treatment error. The dosimetric parameters of PTV and normal tissue were compared between ABC and free breathing (FB). Results The interfraction error in liver positioning showed system errors (Σ) of 3.18mm (ML), 6.80mm (CC) and 3.05mm (AP); random error ( σ ) of 3.03mm (ML), 6.78mm (CC) and 3.62mm (AP). These errors were significantly reduced with CBCT guided online correction. The intrafraction systematic error was 0.72mm (ML), 2.21mm (CC), 1.49mm (AP), and random error was 2.30mm (ML), 3.58mm (CC), 2.49mm (AP). Dosimetric parameters such as PTV, the liver's volume included by 23, 30Gy isodose curve (V23, V30), mean dose to normal liver (MDTNL) and mean dose to cord were significantly larger for FB ( P Conclusion Liver radiotherapy with long time breath-holding at end-inhale is an effective method to reduce liver motion, PTV and dose to normal tissue. Interfraction and intrafraction liver positioning errors were substantial. CBCT guided online correction of positioning error is recommended for liver radiotherapy with end-inhale ABC.

Purpose To evaluate the positioning accuracy of four different immobilizations by use of cone-beam computed tomography guidance for radiotherapy of non–small-cell lung cancer (NSCLC). Methods and Materials Sixty-seven patients with NSCLC received conventional or stereotactic body radiotherapy. Of these, 30 were immobilized with a thermoplastic frame (TF), 16 with a thermoplastic frame and active breathing control (TF-ABC), 7 with a stereotactic body frame (SBF), and 14 with a stereotactic body frame and active breathing control (SBF-ABC). Cone-beam computed tomography scans at initial setup and after correction were registered to planning computed tomography. The positional errors in the left-to-right, superior-inferior, and anterior-posterior directions were analyzed. The planning target volume margins were calculated. Results The precorrection systematic and random errors ranged from 1.9 to 4.2 mm for TF, 1.9 to 4.3 mm for SBF, 1.2 to 5.8 mm for TF-ABC, and 2.3 to 3.9 mm for SBF-ABC. The postcorrection systematic and random errors ranged from 0.3 to 1.9 mm for the four immobilizations. The planning target volume margins (conventional vs. stereotactic body radiotherapy) were 15.6 vs. 13.9 mm (TF), 14.9 vs. 14.8 mm (TF-ABC), 14.4 vs. 13.4 mm (SBF), and 9.9 vs. 9.4 mm (SBF-ABC) before correction and 7.3 vs. 6.9 mm (TF), 4.0 vs. 3.8 mm (TF-ABC), 7.5 vs. 7.1 mm (SBF), and 4.5 vs. 4.2 mm (SBF-ABC) after correction. Conclusions The positioning accuracies of SBF and TF were similar. Active breathing control increased positioning error but reduced internal margin. Cone-beam computed tomography online correction improved the positioning accuracy of NSCLC patients.

Purpose To study the intrafraction tumour position error utilizing cone beam CT (CBCT) in patients receiving radiotherapy. Methods and materials Fifty-four patients were treated with Elekta Synergy S system, including 19 head and neck, 25 thoracic and 10 abdominal-pelvic tumours. All patients received CBCT after initial setup and some of them received CBCT after correction and after treatment. CBCT were registered to planning CT and errors of isocenter position on the left-to-right (LR), superior–inferior (SI) and anterior–posterior (AP) directions were analyzed. Results After treatment the systematic ( Σ ) and random uncertainty ( σ ) increased, the increments of tumour Σ were 0.1–0.3, 0.2–0.5 and 0.2–0.6mm, respectively, while the increments of σ were 0.1–0.3, 0.2–0.4 and 0.1–0.4mm, respectively, for the head and neck, thoracic and abdominal-pelvic tumours. Based on 380 paired pre- and post-treatment CBCT, the intrafraction errors (mean±SD) in the LR, SI and AP directions were −0.1±0.9, −0.3±1.0 and −0.2±0.7mm, respectively, for head and neck tumours, −0.1±1.2, −0.1±1.9 and 0.1±1.3mm, respectively, for thoracic tumours, −0.1±1.1, 0.2±1.4 and −0.1±1.5mm, respectively, for abdominal-pelvic tumours. Isotropic planning margins of 3.4, 6.1 and 5.4mm were generated with linear addition of internal margin (IM) to CTV for the head and neck, thoracic and abdominal-pelvic tumours, respectively, while margins were only 2.4, 4.4 and 3.9mm, respectively, if IM was added in quadrature. Conclusions Utilizing CBCT measurements before and after treatment to detect intrafraction tumour position errors was clinically feasible. The detected intrafraction errors could be applied to improve the accuracy of radiation delivery.

Background To study the set-up errors, PTV margin and toxicity of cone beam CT (CBCT) guided hypofractionated radiotherapy with active breathing control (ABC) for patients with non-small cell lung cancer (NSCLC) or metastatic tumors in lung. Methods 32 tumors in 20 patients were treated. Based on the location of tumor, dose per fraction given to tumor was divided into three groups: 12 Gy, 8 Gy and 6 Gy. ABC is applied for every patient. During each treatment, patients receive CBCT scan for online set-up correction. The pre- and post-correction setup errors between fractions, the interfractional and intrafractional, set-up errors, PTV margin as well as toxicity are analyzed. Results The pre-correction systematic and random errors in the left-right (LR), superior-inferior (SI), anterior-posterior (AP) directions were 3.7 mm and 5.3 mm, 3.1 mm and 2.1 mm, 3.7 mm and 2.8 mm, respectively, while the post-correction residual errors were 0.6 mm and 0.8 mm, 0.8 mm and 0.8 mm, 1.2 mm and 1.3 mm, respectively. There was an obvious intrafractional shift of tumor position. The pre-correction PTV margin was 9.5 mm in LR, 14.1 mm in SI and 8.2 mm in AP direction. After CBCT guided online correction, the PTV margin was markedly reduced in all three directions. The post-correction margins ranged 1.5 to 2.1 mm. The treatment was well tolerated by patients, of whom there were 4 (20%) grade1-2 acute pneumonitis, 3 (15%) grade1 acute esophagitis, 2 (10%) grade1 late pneumonitis and 1 (5%) grade 1 late esophagitis. Conclusion The positioning errors for lung SBRT using ABC were significant. Online correction with CBCT image guidance should be applied to reduce setup errors and PTV margin, which may reduce radiotherapy toxicity of tissues when ABC was used.

Background Whole brain radiotherapy (WBRT) plus sequential focal radiation boost is a commonly used therapeutic strategy for patients with brain metastases. However, recent reports on WBRT plus simultaneous in-field boost (SIB) also showed promising outcomes. The objective of present study is to retrospectively evaluate the efficacy and toxicities of WBRT plus SIB with image guided intensity-modulated radiotherapy (IG-IMRT) for inoperable brain metastases of NSCLC. Methods Twenty-nine NSCLC patients with 87 inoperable brain metastases were included in this retrospective study. All patients received WBRT at a dose of 40 Gy/20 f, and SIB boost with IG-IMRT at a dose of 20 Gy/5 f concurrent with WBRT in the fourth week. Prior to each fraction of IG-IMRT boost, on-line positioning verification and correction were used to ensure that the set-up errors were within 2 mm by cone beam computed tomography in all patients. Results The one-year intracranial control rate, local brain failure rate, and distant brain failure rate were 62.9%, 13.8%, and 19.2%, respectively. The two-year intracranial control rate, local brain failure rate, and distant brain failure rate were 42.5%, 30.9%, and 36.4%, respectively. Both median intracranial progression-free survival and median survival were 10 months. Six-month, one-year, and two-year survival rates were 65.5%, 41.4%, and 13.8%, corresponding to 62.1%, 41.4%, and 10.3% of intracranial progression-free survival rates. Patients with Score Index for Radiosurgery in Brain Metastases (SIR) >5, number of intracranial lesions