Computed Tomography Image Guidance Research Articles

Cone beam computed tomography image guidance within a magnetic resonance imaging-only planning workflow.

Magnetic Resonance Imaging (MRI)-only planning workflows offer many advantages but raises challenges regarding image guidance. The study aimed to assess the viability of MRI to Cone Beam Computed Tomography (CBCT) based image guidance for MRI-only planning treatment workflows. An MRI matching training package was developed. Ten radiation therapists, with a range of clinical image guidance experience and experience with MRI, completed the training package prior to matching assessment. The matching assessment was performed on four match regions: prostate gold seed, prostate soft tissue, rectum/anal canal and gynaecological. Each match region consisted of five patients, with three CBCTs per patient, resulting in fifteen CBCTs for each match region. The ten radiation therapists performed the CBCT image matching to CT and to MRI for all regions and recorded the match values. The median inter-observer variation for MRI-CBCT matching and CT-CBCT matching for all regions were within 2mm and 1 degree. There was no statistically significant association in the inter-observer variation in mean match values and radiation therapist image guidance experience levels. There was no statistically significant association in inter-observer variation in mean match values for MRI experience levels for prostate soft tissue and gynaecological match regions, while there was a statistically significant difference for prostate gold seed and rectum match regions. The results of this study support the concept that with focussed training, an MRI to CBCT image guidance approach can be successfully implemented in a clinical planning workflow.

Quantitative Dual-Energy CT Image Guidance for Thermochemical Ablation: In Vivo Results in the Rabbit VX2 Model

PurposeTo evaluate the feasibility of using dual-energy computed tomography (CT) and theranostic cesium hydroxide (CsOH) for image guidance of thermochemical ablation (TCA) in a rabbit VX2 tumor model. Materials and MethodsIn vivo experiments were performed on New Zealand white rabbits, where VX2 tumor fragments (0.3 mL) were inoculated into the right and left flanks (n = 16 rabbits, 32 tumors). Catheters were placed in the approximate center of 1- to 2-cm diameter tumors under ultrasound guidance. TCA was delivered in 1 of 3 treatment groups: untreated control, 5-M TCA, or 10-M TCA. The TCA base reagent was doped with 250-mM CsOH. Dual-energy CT was performed before and after TCA. Cesium (CS)-specific images were postprocessed on the basis of previous phantom calibrations to determine Cs concentration. Line profiles were drawn through the ablation center. Twenty-four hours after TCA, subjects were euthanized, and the resulting damage was evaluated with histopathology. ResultsCs was detected in 100% of treated tumors (n = 21). Line profiles indicated highest concentrations at the injection site and decreased concentrations at the tumor margins, with no Cs detected beyond the ablation zone. The maximum detected Cs concentration ranged from 14.39 to 137.33 mM. A dose-dependent trend in tissue necrosis was demonstrated between the 10-M TCA and 5-M TCA treatment groups (P = .0005) and untreated controls (P = .0089). ConclusionsDual-energy CT provided image guidance for delivery, localization, and quantification of TCA in the rabbit VX2 model.

Comparative Study of Application of Computed Tomography/Ultrasound and Computed Tomography Imaging Guidance Methods in the Microwave Ablation of Liver Cancer.

The aim of the study is to assess the clinical value of the combined computed tomography (CT)/ultrasound (US) guidance in microwave ablation (MWA) for hepatocellular carcinoma (HCC). From July 16, 2016, to June 20, 2021, medical records of 150 HCC patients treated with MWA were retrospectively analyzed. Ninety-two patients with 115 liver tumors underwent MWA under combined CT/US guidance, and 58 patients with 73 liver tumors received MWA under CT guidance alone. The clinical efficacy of combined CT/US-guided MWA was analyzed. We compared the complications, procedure time, and CT scan times between the 2 groups. The total complete ablation rate and complete ablation rate of high-risk location tumors were significantly higher in the group treated with combined CT/US guidance ( P = 0.0471 and P = 0.0347, respectively), the imaging guidance modality (odds ratio, 0.303; 95% confidence interval [CI], 0.095-0.970; P = 0.044) was an independent factor for ablation efficacy. These 2 groups also had significant differences in the procedure time ( P = 0.0171), the incidence rate of pneumothorax ( P = 0.0209), abdominal pain ( P = 0.0196), nausea or vomiting ( P = 0.0026), and intraoperative CT scan times ( P < 0.001). The overall complication rates ( P = 0.4023) and recurrence rates ( P = 0.5063) between the 2 groups were not statistically significant. However, CT/US group has a better short-term progressive free survival (log-rank P = 0.103, Breslow P = 0.030). In multivariate analysis, guidance modality (hazard ratio, 0.586; 95% CI, 0.368-0.934; P = 0.025) and Barcelona Clinic Liver Cancer stage (hazard ratio, 2.933; 95% CI, 1.678-5.127; P < 0.001) were risk factor for progressive free survival. Percutaneous MWA under the combined CT/US guidance for HCC can improve clinical benefits.

THE EFFECTS OF CONE-BEAM COMPUTED TOMOGRAPHY IMAGING GUIDANCE ON PATIENT RADIATION EXPOSURES IN TRANS-ARTERIAL CHEMOEMBOLISATION FOR HEPATOCELLULAR CARCINOMA

This study investigated the effects of cone-beam computed tomography (CBCT) guidance in trans-arterial chemoembolisation (TACE) procedures on the number of digital subtraction angiography (DSA) runs acquired and total patient radiation exposure in patients with hepatocellular carcinoma (HCC). A retrospective, analytical cross-sectional, single institution, study was conducted. Dose data were compared across the control (DSA guidance alone) and study (DSA and CBCT guidance) groups. A total of 122 procedures were included within the study. There was a significant reduction in the number of DSA runs (3 vs 5, p < 0.001) and DSA air kerma-area product (PKA) (3077.3 vs 4276.6 μGym2, p = 0.042) for the study group when compared to the control group. Total procedural PKA and total procedural reference air kerma (Ka,r) were shown to be 50 and 73% higher, respectively, for the study group when compared to the control group. CBCT imaging guidance does reduce the number of DSA runs and DSA PKA required to complete the TACE procedure for patients diagnosed with HCC; however, a substantial increase in total procedural PKA is to be expected and it is thus important that this increased dose is carefully considered and justified.

Total workflow uncertainty of frameless radiosurgery with the Gamma Knife Icon cone-beam computed tomography.

ObjectiveFrameless treatment with the Gamma Knife Icon is still relatively new as a treatment option. As a result, additional confidence/knowledge about the uncertainty that exists within each portion of the treatment workflow could be gained especially regarding steps that have not been previously studied in the literature.MethodsThe Icon base delivery device (Perfexion) uncertainty is quantified and validated. The novel portions of the Icon such as mask immobilization, cone‐beam computed tomography image guidance, and the intrafraction motion management methods are studied specifically and to a greater extent to determine a total workflow uncertainty of frameless treatment with the Icon.ResultsThe uncertainty of each treatment workflow step has been identified with the total workflow uncertainty being identified in this work as 1.3 mm with a standard deviation of 0.51 mm.ConclusionThe total uncertainty of frameless treatment with the Icon has been evaluated and this data may indicate the need for setup margin in this setting with data that could be used by other institutions to calculate needed setup margin per their preferred recipe after validation of this data in their context.

AuNRs@MIL-101-based stimuli-responsive nanoplatform with supramolecular gates for image-guided chemo-photothermal therapy

Multimodal theranostic nanoplatform with multi-functions in diagnosis and treatment could be achieved by combining inorganic nanoparticles and intelligent composite materials such as metal-organic frameworks. In this study, a stimuli-responsive theranostic nanoplatform with well-defined architectures and the capability of computed tomography imaging guidance, tumorous microenvironment-triggered drug release, and effective chemo-photothermal synergistic therapy has been designed by encapsulating gold nanorods (AuNRs) with MIL-101 metal-organic framework, followed by the installation of carboxylatopillar[5]arene (CP[5]A)-based supramolecular gates. The pillararene gates on the surface of the MIL-101 shell enhance the drug loading capacity of the carrier and endow the resulting hybrid AuNRs@MIL-101(Fe)–NH2@CP[5]A nanoparticles with controlled release function in response to multi-stimuli, including pH, temperature, and Ca2+ ion. The obtained AuNRs@MIL-101(Fe)–NH2@CP[5]A nanoparticles system allows the sustained release of anticancer drug 5-fluorouracil over five days for an effectively prolonged treatment, demonstrating the promising potential of a comprehensive multimodal theranostic nanoplatform in clinical investigations.

Dosimetric Uncertainties Resulting From Interfractional Anatomic Variations for Patients Receiving Pancreas Stereotactic Body Radiation Therapy and Cone Beam Computed Tomography Image Guidance

PurposeTo estimate the effects of interfractional anatomic changes on dose to organs at risk (OARs) and tumors, as measured with cone beam computed tomography (CBCT) image guidance for pancreatic stereotactic body radiation therapy. Methods and MaterialsWe evaluated 11 patients with pancreatic cancer whom were treated with stereotactic body radiation therapy (33-40 Gy in 5 fractions) using daily CT-on-rails (CTOR) image guidance immediately before treatment with breath-hold motion management. CBCT alignment was simulated in the treatment planning software by aligning the original planning CT to each fractional CTOR image set via fiducial markers. CTOR data sets were used to calculate fractional doses after alignment by applying the rigid shift of the planning CT and CTOR image sets to the planning treatment isocenter and recalculating the fractional dose. Accumulated dose to the gross tumor volume (GTV), tumor vessel interface, duodenum, small bowel, and stomach were calculated by summing the 5 fractional absolute dose-volume histograms into a single dose-volume histogram for comparison with the original planned dose. ResultsFour patients had a GTV D100% of at least 1.5 Gy less than the fractional planned value in several fractions; 4 patients had fractional underestimation of duodenum dose by 1.0 Gy per fraction. The D1.0 cm3 <35 Gy constraint was violated for at least 1 OAR in 3 patients, with either the duodenum (n = 2) or small bowel (n = 1) D1.0 cm3 being higher on the accumulated dose distribution (P = .01). D100% was significantly lower according to accumulated dose GTV (P = .01) and tumor vessel interface (P = .02), with 4 and 2 patients having accumulated D100% ≥4 Gy lower than the planned value for the GTV and tumor vessel interface, respectively. ConclusionsFor some patients, CBCT image guidance based on fiducial alignment may cause large dosimetric uncertainties for OARs and target structures, according to accumulated dose.

Abstract No. 231 Cone-beam computed tomography image guidance for combined ablation-embolization treatment of hepatic malignancies

We aim to demonstrate the utility of cone-beam computed tomography (CBCT) image guidance in combining transarterial chemoembolization (TACE) or radioembolization (TARE) with percutaneous microwave ablation for the treatment of hepatic malignancies.

A Preliminary Study on Animal Experiments of Robot-Assisted Craniotomy

Traditional craniotomy relies on the surgeon's experience and can be complicated owing to excessive skull bone removal, undesirable brain tissue penetration, or severe bleeding. For craniotomy, we developed a robot system based on intraoperative cone-beam computed tomography image guidance and human-robot cooperative interaction, aiming to improve the safety and accuracy of surgery and reduce the labor-intensiveness of the procedure. Intraoperative cone-beam computed tomography image guidance was adopt to improve the accuracy in our experiment. Craniotomy was performed using an interactive method based on human-robot collaboration, which could achieve a natural interactive method in accordance with surgeons' operating habits. The frequency-based method of contact distinction and the method of torque estimation were used to improve the safety of the designed robot. An animal experiment was conducted to verify the effectiveness of the robot system. During the drilling process, the position error was 0.92 ± 0.17 mm (upper surface) and 0.97 ± 0.11 mm (lower surface), and the angle error was 3.37 ± 1.43°. During the milling process, the position error was 1.06 ± 0.13 mm (upper surface) and 1.09 ± 0.09 mm (lower surface). The results showed that the system had sufficient precision and could better complete craniotomy with human-robot collaboration. In addition, with the feedback of multisensor information, the robot system could achieve a sufficient level of safety. The robot system can achieve accurate positioning and safe user-friendly human-robot interaction, which solves problems encountered in the drilling and milling of craniotomy, meets clinical needs, and provides a new method for robot-assisted craniotomy.

Effectiveness and safety of irreversible electroporation for recurrent hepatocellular carcinoma ineligible for thermal ablation after surgery

ObjectivesTo preliminarily evaluate the clinical effectiveness and safety of computed tomography (CT) image-guided irreversible electroporation (IRE) for the treatment of recurrent hepatocellular carcinoma (HCC) after surgical resection. MethodsFrom January 2016 to February 2018, 18 patients diagnosed with recurrent HCC after surgical resection received IRE under CT image guidance for 22 tumors. Patients were enrolled for IRE when ineligible for thermal ablation due to tumor location. Clinical records and imaging data were reviewed to assess complete ablation rate, local tumor progression free rate (LTPFR), local tumor progression free survival (LTPFS) and complications after a median follow-up time of 14 months. ResultsSuccessful complete ablations were achieved in 20/22 (90.1%) tumors. Mean LTPFS was 10.5 ​± ​9.4 months. Overall 3-, 6- and 12-months LTPFR in 22 tumors following IRE were 68.2% (95% confidence interval [CI]: 45%–83%), 59.1% (95% CI: 33%–76%) and 36.4% (95% CI: 17%–56%), respectively. Complications included pneumothorax (2/18, 11.1%), localized pain (3/18, 16.7%), bile duct dilation (1/18, 5.6%) and transient hypertension (1/18, 5.6%). No major complications or treatment-related deaths were observed. The alpha-fetoprotein levels of two patients decreased to the normal range at 3 and 4 months, respectively. ConclusionsThis study showed that percutaneous CT image-guided IRE can serve as a safe and effective treatment for recurrent HCC not suitable for thermal ablation.

Daily computed tomography image guidance: Dosimetric advantages outweigh low-dose radiation exposure for treatment of mediastinal lymphoma

CT-guided treatment delivery can improve target localization in mediastinal lymphoma patients treated with “butterfly” intensity-modulated radiotherapy and deep-inspiration breath hold. Although daily CT imaging adds additional radiation exposure, its use may be justified given the greater normal tissue sparing enabled by PTV margin reduction.

Tumor Microenvironment Targeting Nano-Bio Emulsion for Synergistic Combinational X-Ray PDT with Oncolytic Bacteria Therapy.

Various cancer therapies have been developed, but tumor recurrence with incomplete tumor killing and remaining tumor cells/tissues is frequent in monotherapies. Herein, a nano-bio therapeutic emulsion formulated with multifunctional nanoscintillators and anaerobic Clostridium novyi-NT spores for synergistic image-guided combinational cancer therapy is reported. MRI visible nanoscintillators (NSs) are synthesized with a NaGdF4 :Tb,Ce@NaGdF4 core/shell structure for an image-guided X-ray photodynamic therapy (PDT) of the normoxic peripheral tumor. An anaerobic oncolytic bacterium (C. novyi-NT) therapy is combined to treat the hypoxic central tumor tissues. Photosensitizer-coated NSs (PS-NSs) and C. novyi-NT spores are emulsified with clinically available ethiodized oil (Lipiodol) to be the nano-bio therapeutic emulsion and injected into the tumor with computed tomography image guidance. The distribution of nano-bio therapeutic emulsion, including PS-NSs and anaerobic C. novyi-NT spores in the tumor site, is confirmed by both X-ray and T1 -weighted magnetic resonance imaging. Following the image-guided X-ray PDT and anaerobic C. novyi- NT combination treatment, apoptotic cell death in cancer tissues, including both peripheral and central tumor regions, is significantly higher than in the control groups. This combination therapy approach using a nano-bio therapeutic emulsion is expected to overcome the limitations of conventional cancer therapy, resulting in increased cancer-therapeutic efficacy.

Assessment of unintended shifts during frame-based stereotactic radiosurgery using cone beam computed tomography image guidance.

To investigate the frequency, magnitude and possible causes of frame-shifts that may occur between treatment planning and treatment delivery when performing Gamma Knife radiosurgery with rigid frame-based immobilization. Differences between computed tomography (CT) framed fiducial stereotactic coordinate reference and cone beam computed tomography stereotactic coordinates after image registration were recorded for 49 frame-based GK radiosurgery cases performed using the Gamma Knife Icon. Parameters recorded include rotational shifts, translational shifts, and the GK-computed Maximum Shot Displacement (MSD) between the two stereotactic coordinate spaces. Other patient-specific parameters were collected and linear regression analysis was performed to evaluate predictors of increased displacement. The median values of rotational shifts were: pitch 0.14°, yaw 0.17°, and roll 0.13°. The median absolute values of translational shifts were: left-right 0.39mm, anteroposterior 0.14mm, and superior-inferior 0. 22mm. The median value of MSD was 0.71mm. Twelve cases (24.5%) had a MSD of greater than 1.0mm. Male gender was associated with increased MSD (p = 0.013) and translational shifts (root-mean-squared value, p = 0.017). Cases with large differences between right and left sided pin lengths were also associated with increased MSD (p = 0.011). The use of CBCT image guidance in frame-based GK radiosurgery allows unintended frame shifts to be identified and corrected. A significant fraction (24.5%) of patients had large enough shifts to result in a MSD of greater than 1.0mm. Male gender and eccentrically placed frames were associated with increased MSD, and particular care should be taken in these cases.

Three-dimensional-Printed Computed Tomography-Based Bone Models for Spine Surgery Simulation.

We present a novel 3-dimensional (3D) printing method for low-cost and widely available reproduction of computed tomography (CT)-based synthetic bone models for spine surgery simulation, optimized to reproduce realistic haptic properties. The method allows reproduction of either normal or abnormal patient anatomy. The models are fluoroscopy compatible and contain deformities and fractures present in the underlying CT data. Spine models created from CT data were printed on a 3D printer using 2 different materials for cortical and cancellous bone. Printing parameters were iteratively optimized with surgical experts and 3 candidate spine models were evaluated in a study regarding haptic properties. X-ray images of a spine section printed with final printing parameters were evaluated by surgical experts regarding fluoroscopic properties. Eleven surgical experts performed a trocar insertion, a typical workflow step in spine surgery procedures, on the models. We observed agreement that cortical structures and strong agreement that cancellous structures of the final model are haptically comparable with human vertebral bone. Ten surgical experts evaluated x-ray images of the model. They expressed strong agreement on the similarity with x-ray images of the human spine and confirmed the presence of a fracture. Material cost of a typical spine model is around US $11. Models created using the novel methodology realistically reproduce the haptic properties during a trocar placement into the vertebral body. The models are compatible with conventional x-ray imaging. Because the models correspond to real patient CT data, those can alternatively be used in simulation environments that simulate fluoroscopy or CT image guidance to produce highly realistic, radiation-free imaging output.

Non-Invasive Targeted Hepatic Irradiation and SPECT/CT Functional Imaging to Study Radiation-Induced Liver Damage in Small Animal Models.

Radiation therapy (RT) has traditionally not been widely used in the management of hepatic malignancies for fear of toxicity in the form of radiation-induced liver disease (RILD). Pre-clinical hepatic irradiation models can provide clinicians with better understanding of the radiation tolerance of the liver, which in turn may lead to the development of more effective cancer treatments. Previous models of hepatic irradiation are limited by either invasive laparotomy procedures, or the need to irradiate the whole or large parts of the liver using external skin markers. In the setting of modern-day radiation oncology, a truly translational animal model would require the ability to deliver RT to specific parts of the liver, through non-invasive image guidance methods. To this end, we developed a targeted hepatic irradiation model on the Small Animal Radiation Research Platform (SARRP) using contrast-enhanced cone-beam computed tomography image guidance. Using this model, we showed evidence of the early development of region-specific RILD through functional single photon emission computed tomography (SPECT) imaging.

Intrafractional motion in stereotactic body radiotherapy of spinal metastases utilizing cone beam computed tomography image guidance.

Spine stereotactic body radiotherapy (SBRT) requires a high degree of accuracy due to steep dose gradients close to the spinal cord. This study aimed to (1) evaluate intrafractional motion in spine SBRT utilizing flattening filter free (FFF) beam delivery and cone beam computed tomography (CBCT) image guidance and (2) evaluate if adding another CBCT acquisition and corrections prior to treatment improves the overall position accuracy. Intrafractional motion was retrospectively analyzed for 78 fractions in 54 patients. All patients were immobilized with an evacuated cushion. Before treatment, a CBCT was acquired, a bony fusion with the planning CT was performed and translational and rotational errors were corrected. For 30 of the patients (39 fractions) acquisition of another CBCT and corrections were performed before treatment. A post treatment CBCT was acquired for all patients, and translational and rotational errors measured by fusion of the post treatment CBCT with the planning CT were recorded to calculate means and standard deviations (SDs). The positional errors were significantly smaller in 4 out of 6 error values in the patient group treated with verification CBCT. In this group, translational and rotational SDs ranged from 0.5 to 0.6 mm and 0.3°, respectively. Corresponding values in the group treated without verification CBCT were 0.7-1.0 mm and 0.4-0.7°. With proper CBCT image guidance, patient immobilization and FFF-beam delivery, one can obtain very high patient position accuracy in spine SBRT. Inclusion of a verification CBCT prior to treatment increases the overall position accuracy.

Determination of Stereotactic Shifts for Frame-Based Stereotactic Radiosurgery Using Cone-Beam Computed Tomography Image Guidance

Determination of Stereotactic Shifts for Frame-Based Stereotactic Radiosurgery Using Cone-Beam Computed Tomography Image Guidance

Electromagnetic Transponder Based Tracking and Gating in the Radiotherapeutic Treatment of Thoracic Malignancies

PurposeThis report details our institutional workflow and technique for use of the Calypso electromagnetic transponder system with respiratory gating for localization and tracking of lung tumors during stereotactic radiation therapy for early stage thoracic malignancies. Methods and MaterialsSixteen patients underwent bronchoscopic fiducial placement of 3 transponders in small airways in proximity to the primary tumor. Transponders were placed <19 cm from the most anterior skin location of the patient for appropriate tracking functionality. Patients underwent simulation with 4-dimensional assessment and were treated with transponder based positional gating if tumors moved >5 mm in any direction. Tumor motion <5 mm was not gated and treated using an internal target volume approach. A 5 mm uniform planning target volume was used. Before treatment, fiducial placement and tumor location were verified by daily kilovoltage (kV) and cone beam computed tomography image guidance. Tracking limits were placed based on the movement of the transponders from the centroid of the structures on the maximum intensity projection image. The Calypso treatment system paused treatment automatically if beacons shifted beyond the predefined tracking limits. ResultsAll 16 patients underwent successful implantation of the electromagnetic transponders. Eight patients exhibited tumor motion sufficient to require respiratory gating, and the other 8 patients were treated using a free breathing internal target volume technique. Difficulty with transponder sensing was experienced in 3 patients as a result of anatomic interference with the placement of the sensing arrays; each of these cases was successfully treated after making setup modifications. Triggered imaging of fiducials during treatment was consistent with real-time positioning determined by the Calypso tracking system. ConclusionsRespiratory gated electromagnetic based transponder guided stereotactic body radiation therapy using the workflow described is feasible and well tolerated in selected patients with early stage lung malignancies.

Image-guided transnasal endoscopic fine needle aspiration or biopsy of parapharyngeal space tumours.

Parapharyngeal space biopsy is an important investigation in the management of parapharyngeal space tumours. These tumours are relatively rare and the surgeon is often faced with a wide range of differential diagnoses. There are several ways to access the parapharyngeal space, with varying degrees of associated morbidity. This paper describes a seldom used, but a simple and safe, image-guided endoscopic approach to parapharyngeal space biopsy that enables tissue to be obtained transnasally. The procedure is conducted under general anaesthesia using computed tomography image guidance via the LandmarX system, with transnasal access to the parapharyngeal space achieved using a sampling needle. This procedure is relatively simple, safe and reproducible. It is a less invasive approach to parapharyngeal space biopsy, and one which has been successfully used by the senior author for years without any significant morbidity. Transnasal image-guided endoscopic aspiration or biopsy of the parapharyngeal space is a novel technique that has not been previously described.

(P57) The Accuracy of Stereotactic Radiosurgery With Cone Beam Computed Tomography Image Guidance for Trigeminal Neuralgia

(P57) The Accuracy of Stereotactic Radiosurgery With Cone Beam Computed Tomography Image Guidance for Trigeminal Neuralgia