Phantom-based evaluation of dose exposure of ultrafast combined kV-MV-CBCT towards clinical implementation for IGRT of lung cancer

The radioenhancement potential of Schiff base derived copper (II) compounds against lung carcinoma in vitro

For the last years, copper complexes have been intensively implicated in biomedical research as components of cancer treatment. Herewith, we provide highlights of the synthesis, physical measurements, structural characterization of the newly developed Cu(II) chelates of Schiff Bases, Cu(Picolinyl-L-Tryptopahanate)2, Cu(Picolinyl-L-Tyrosinate)2, Cu(Isonicotinyl-L-Tyrosinate)2, Cu(Picolinyl-L-Phenylalaninate)2, Cu(Nicotinyl-L-Phenylalaninate)2, Cu(Isonicotinyl-L-Phenylalaninate)2, and their radioenhancement capacity at kV and MV ranges of irradiation of human lung carcinoma epithelial cells in vitro. The methods of cell growth, viability and proliferation were used. All compounds exerted very potent radioenhancer capacities in the irradiated lung carcinoma cells at both kV and MV ranges in a 100 μM concentration. At a concentration of 10 μM, only Cu(Picolinyl-L-Tyrosinate)2, Cu(Isonicotinyl-L-Tyrosinate)2, Cu(Picolinyl-L-Phenylalaninate)2 possessed radioenhancer properties at kV and MV ranges. Cu(Picolinyl-L-Tryptophanate)2 showed radioenhancer properties only at kV range. Cu(Nicotinyl-L-Phenylalaninate)2 and Cu(Isonicotinyl-L-Phenylalaninate)2 showed remarkable radioenhancer activity only at MV range. All compounds acted in dose-dependent manner at both tested energy ranges. These copper (II) compounds, in combination with 1 Gy irradiation at either 120 kV or 6 MV, are more efficient at delaying cell growth of lung cancer cells and at reducing cell viability in vitro than the irradiation administered alone. Thus, we have demonstrated that the studied copper compounds have a good potential for radioenhancement.

Noise-robust breathing-phase estimation on marker-free, ultra low dose X-ray projections for real-time tumor localization via surrogate structures

PURPOSE

This paper presents a novel strategy for feature-based breathing-phase estimation on ultra low-dose X-ray projections for tumor motion control in radiation therapy.

METHODS

Coarse-scaled Curvelet coefficients are identified as motion sensitive but noise-robust features for this purpose. For feature-based breathing-phase estimation, an ensemble strategy with two classifiers is used. This consensus-based estimation substantially increases tracking reliability by rejection of false positives. The algorithm is evaluated on both synthetic and measured phantom data: Monte Carlo simulated ultra low dose projections for a C-arm X-ray and on the basis of 4D-chest-CTs of eight patients on one hand side and real measurements based on a motion phantom.

RESULTS

To achieve an accuracy of breathing-phase estimation of more than 95% a fluence between 20 and 400 photons per pixel (open field) is required depending on the patient. Furthermore, the algorithm is evaluated on real ultra low dose projections from an XVI R5.0 system (Elekta AB, Stockholm, Sweden) using an additional lead filter to reduce fluence. The classifiers-consensus-based-gating method estimated the correct position of the test projections in all test cases at a fluence of ∼180 photons per pixel and 92% at a fluence of ∼40 photons per pixel. The deposited dose to patient per image is in the range of nGy.

CONCLUSIONS

A novel method is presented for estimation of breathing-phases for real-time tumor localization at ultra low dose both on a simulation and a phantom basis. Its accuracy is comparable to state of the art X-ray based algorithms while the released dose to patients is reduced by two to three orders of magnitude compared to conventional template-based approaches. This allows for continuous motion control during irradiation without the need of external markers.

Efficacy and Safety of Iodine-125 Brachytherapy in the Treatment of Recurrent or Metastatic Head and Neck Squamous Cell Carcinoma

Background

Recurrent or metastatic (R/M) head and neck squamous cell carcinoma (HNSCC) is a difficult challenge for physicians, especially when patients have been treated with external beam radiotherapy. The purpose of this study was to assess the clinical efficacy and safety of computed tomography (CT)-guided iodine-125 brachytherapy as a palliative treatment for R/M HNSCC.

Methods

From May 2011 to July 2018, we enrolled 87 patients with R/M HNSCC who had previously received external beam radiotherapy. Among these patients, 43 successfully underwent CT-guided iodine-125 brachytherapy and chemotherapy (group A); 44 patients who only received chemotherapy (group B) were matched with patients in group A. Patients' pain score, Eastern Cooperative Oncology Group (ECOG) score, tumor compression symptoms, and side effects of iodine-125 implantation were recorded. Clinical follow-up was performed to assess progression-free survival (PFS) and overall survival (OS).

Results

Both groups of patients completed the treatment and were followed up for 9-66 months, with a median follow-up time of 44 months. The OS was 51 months (95% CI: 42.93-59.06 months) versus 28 months (95% CI: 23.79-32.21 months) (p < 0.05), the PFS was 10 months (95% CI: 6.15-13.84 months) versus 6 months (95% CI: 4.40-7.59 months) (p < 0.05) in groups A and B, respectively. The RR in group A was 25/43 (58.14%) versus 15/44 (34.10%) in group B (p < 0.05). Compared with group B, patients in group A had lower pain scores, better physical performance, and better improvement of compression symptoms. No serious treatment-related complications were observed in either group of patients.

Conclusion

Compared with chemotherapy alone, iodine-125 seed implantation combined with chemotherapy was a more effective and safer strategy for R/M HNSCC.

Efficacy and safety of iodine-125 brachytherapy combined with chemotherapy in the treatment of advanced NSCLC in the elderly

Background

Advanced non-small-cell lung cancer (NSCLC) is a huge challenge for physicians. Traditional chemoradiotherapy is associated with high rates of toxicities, especially when treating gerontal patients. Our study was focused on investigating the safety and efficacy of permanent iodine-125 seed implantation and chemotherapy for the treatment of advanced NSCLC in the elderly.

Methods

Fifty elderly patients with stage III or IV NSCLC at our hospital from January 2011 to June 2017 were treated with the chemotherapy regimens (paclitaxel/cisplatin) and computed tomography (CT)-guided iodine-125 brachytherapy (group A), 50 patients who received chemotherapy consisting of paclitaxel and cisplatin only (group B) were matched-up with the patients in group A. The local response rate was evaluated by CT. Progression-free survival (PFS) and overall survival (OS) data were obtained through clinical follow-up.

Results

The patients were followed-up for 3-46 months. With a median follow-up time of 20 months, the OS and PFS were 20 months (95% CI: 19.09-20.90 months) vs 15 months (95% CI: 14.48-15.51 months) (P<0.05) and 13 months (95% CI: 11.96-14.04 months) vs 8 months (95% CI: 7.63-8.37 months) (P<0.05) in group A and group B, respectively. The symptoms of patients in group A were significantly relieved when compared with group B. Severe complications were not observed in either of the groups.

Conclusion

The combination of iodine-125 seed brachytherapy and chemotherapy is an effective and safe therapy and is superior to chemotherapy alone for advanced NSCLC in the elderly.

Automated ultrafast kilovoltage-megavoltage cone-beam CT for image guided radiotherapy of lung cancer: System description and real-time results

PURPOSE

To establish a fully automated kV-MV CBCT imaging method on a clinical linear accelerator that allows image acquisition of thoracic targets for patient positioning within one breath-hold (∼15s) under realistic clinical conditions.

METHODS AND MATERIALS

Our previously developed FPGA-based hardware unit which allows synchronized kV-MV CBCT projection acquisition is connected to a clinical linear accelerator system via a multi-pin switch; i.e. either kV-MV imaging or conventional clinical mode can be selected. An application program was developed to control the relevant linac parameters automatically and to manage the MV detector readout as well as the gantry angle capture for each MV projection. The kV projections are acquired with the conventional CBCT system. GPU-accelerated filtered backprojection is performed separately for both data sets. After appropriate grayscale normalization both modalities are combined and the final kV-MV volume is re-imported in the CBCT system to enable image matching. To demonstrate adequate geometrical accuracy of the novel imaging system the Penta-Guide phantom QA procedure is performed. Furthermore, a human plastinate and different tumor shapes in a thorax phantom are scanned. Diameters of the known tumor shapes are measured in the kV-MV reconstruction.

RESULTS

An automated kV-MV CBCT workflow was successfully established in a clinical environment. The overall procedure, from starting the data acquisition until the reconstructed volume is available for registration, requires ∼90s including 17s acquisition time for 100° rotation. It is very simple and allows target positioning in the same way as for conventional CBCT. Registration accuracy of the QA phantom is within ±1mm. The average deviation from the known tumor dimensions measured in the thorax phantom was 0.7mm which corresponds to an improvement of 36% compared to our previous kV-MV imaging system.

CONCLUSIONS

Due to automation the kV-MV CBCT workflow is speeded up by a factor of >10 compared to the manual approach. Thus, the system allows a simple, fast and reliable imaging procedure and fulfills all requirements to be successfully introduced into the clinical workflow now, enabling single-breath-hold volume imaging.