Application of Bodyfix fixation device in stereotactic body radiotherapy for elderly patients with lung cancer / 肿瘤研究与临床

Objective:To explore the clinical application value of Bodyfix fixation device in stereotactic body radiotherapy (SBRT) for elderly patients with lung cancer.Methods:The clinical data of 63 elderly patients with lung cancer who received SBRT in Tongji Hospital Affiliated to Tongji Medical College of Huazhong University of Science and Technology from January to October 2021 were retrospectively analyzed. According to different fixation methods, the patients were divided into Bodyfix combined with vacuum bag fixation device group (Bodyfix group, 20 cases) and 4D respiratory gating technology combined with vacuum bag fixation device group (vacuum bag group, 43 cases). Cone beam CT (CBCT) was used for position verification before each treatment, linear and rotational errors in the horizontal (X), head-to-foot (Y), front-to-back (Z) directions were recorded.Results:The linear errors of Bodyfix group in the X, Y and Z directions were 1.7 mm (1.3 mm, 3.0 mm), 4.6 mm (4.3 mm, 5.3 mm) and 1.3 mm (0.8 mm, 2.8 mm), and the rotational errors were (0.46±0.04)°, (-0.48±0.05)° and 0.64°(0.38°, 1.07°); the linear errors of vacuum bag group in the X, Y and Z directions were 2.1 mm (1.6 mm, 3.3 mm), 2.8 mm (1.8 mm, 3.7 mm) and 3.0 mm (2.3 mm, 3.8 mm), and the rotational errors were (0.69±0.04)°, (-0.70±0.04)° and 0.64° (0.42°, 0.86°). The differences in linear errors in the Y and Z directions and rotational errors in the X and Y directions between the two groups were statistically significant ( P values were <0.001, <0.001, 0.003 and 0.007). Conclusions:Compared with the 4D respiratory gating technology, the Bodyfix fixation device has smaller rotational errors in the X and Y directions and linear errors in the Z direction. It can be used as an effective method of postural fixation for SBRT in elderly patients with lung cancer.

Application of prospective respiratory gating based on 4D-CT in precise radiotherapy for lung cancer / 中华放射肿瘤学杂志

Objective:The respiratory waveform of lung cancer patients based on 4D-CT respiratory gating was analyzed to evaluate the accuracy of gating during radiotherapy, and to explore the off-target in the 4D-CT respiratory gating radiotherapy.Methods:Clinical data of 18 patients with lung cancer admitted to Radiotherapy Department of Jiangsu Cancer Hospital were collected to obtain the respiratory waveform data during 4D-CT respiratory gating radiotherapy. The waveform in each treatment working cycle was compared with the waveform in 4D-CT scan to study whether there was a possibility of the off-target in the treatment of lung cancer patients.Results:There were 154 treatment sessions and 20,790 treatment breathing cycles in 18 patients, among which the threshold of gated opening beam miss amplitude (Δm-en) was greater than 0 in 95 treatment breathing cycles in 7 patients, accounting for 0.46% of all breathing cycles, and the threshold of gated closing beam miss amplitude (Δm-dis) was greater than 0 in 1419 treatment breathing cycles in 13 patients, accounting for 6.83% of all cycles. Among the 13 patients withΔm-dis greater than 0, actual tumor range of motion (R G) was greater than the sum of the value of target margin (M) and the value of plan tumor range of motion (R T) in 7 patients, R G was more than 1.5 times of M+R T in 7 patients, and there were also 7 patients in the phase of rapid rise and fall of respiratory curve. The correlation efficients between R G-M-R T and the percentage of beam on miss phase (T en%) and the percentage of beam closing off phase (T dis%) were 0.41 and 0.57, respectively. Conclusion:When R G is more than 1.5 times of M+R T value and the gating beam on phase contains the phases in the rapid rise and fall of the respiratory curve, the possibility of the off-target during radiotherapy is significantly increased.

Impact of the Varian real-time position management respiratory gating system on radiotherapy planning dosimetry / 中华放射医学与防护杂志

Objective:To study the impact of the Varian real-time position management (RPM) respiratory gating system on radiotherapy planning dosimetry.Methods:The radiotherapy plans of 40 cases with thoracic or abdominal tumors were retrospectively selected in this study. The motion phantom for quality control was adopted to generate respiratory gating signals, and the 30%-60% stable phase at the end of expiratory was selected as the respiratory gating window. The dose verification for the abovementioned radiotherapy plans was performed using the Portal Dosimetry (PD) system under RPM respiratory gating mode with the Edge accelerator. Afterwards, dose analysis was performed with different γ passing rate criteria and the distribution characteristics of γ values were analyzed. Finally, the verification results between the non-gating mode and the gating mode were compared.Results:Under the respiratory gating mode, the passing rates of all intensity-modulated radiation therapy/volumetric-modulated arc therapy (IMRT/VMAT) plans with or without flattening filters were over 95.5% by γ criteria of (3%, 3 mm) or (3%, 2 mm) and were over 90% by stricter γ criteria of (2%, 2 mm). All plans met the clinical requirements recommended by the American Association of Physicists in Medicine (AAPM). The passing rates of dose verification under non-gating mode were slightly better than those under respiratory gating mode, and the differences between the two modes were statistically significant (3%/3 mm, Z =-1.45; 3%/2 mm, Z =-2.86; 2%/2 mm, Z =-3.70; 1%/1 mm, Z =-4.52; P<0.05). There was no significant difference in the minimum and maximum values of γ and the share of γ > 1.5 of plan verification result under the two modes. However, the average value and standard deviation of the γ were generally smaller under the non-gating mode. Conclusions:The impact of the introduction of RPM respiratory gating technology on dose is clinically acceptable, and the execution of these plans in this gating mode is safe and reliable.

Dosimetry advantage of respiratory gating in the treatment of hepatocellular carcinoma with large segmentation / 实用肿瘤学杂志

Objective The aim of this study was to investigate the dosimetric advantages of Gating in the treatment of prima-ry hepatic cancer with large segmentation. Methods A retrospective analysis of 10 patients with primary liver cancer from August 2017 to November 2018 after interventional therapy was performed using three consecutive phases of end-tidal phase to achieve pa-tient-controlled large-segment radiotherapy. Ten patients underwent 4DCT localization scan,and 10 respiratory phase sequences were reconstructed by respiratory wave-form,and the images were transmitted to the MIM6. 7. 6 workstation. In the MIM workstation, full-time phase maximum density projection(MIP-10),full-time phase average density projection(Mean-10),end-expiration 3 phase maximum density projection(MIP-3) and end-expiration 3 phase average density projection( Mean-3) were generated re-spectively,where MIP was used for target delineation and Mean for dose calculation. The radiotherapy doctor delineated IGTV-10 and IGTV-3 on the MIM workstation,and released CTV-10,CTV-3,PTV-10 and PTV-3 to compare the volume differences of the target area. After the target area was drawn,the image was transmitted from the MIM workstation to the Eclipse treatment planning sys-tem,and the full-time phase plan(Plan-10)with the same conditions and three consecutive phase-phase gating plans(Plan-3) were prepared. The prescriptive dosage was given at 50 Gy/10 f/2weeks. Comparing the HI and CI of the target area,the comparison of organs at risk included: the average dose of liver Dmean,the irradiation volume of liver less than 15Gy,the Dmax of small intestine, the Dmax of colon, the Dmax of stomach, the average dose of the kidney Dmean, the heart Dmax, and the spinal cord Dmax. Results The volume of the target area delineated at the end of expiratory phase was less than that of the target area outlined by the full-time phase in IGTV,CTV and PTV,and the difference was statistically significant(P<0. 05). In the two groups of seven field coplanar lage-segment radiotherapy plans,the 3-phase respiratory gating plan significantly reduced the dose of the organs at risk, and the difference was statistically significant(P<0. 05). At the same time,there was no statistically difference in the HI and CI be-tween of the two groups(P>0. 05). Conclusion The gated target area delineation and planning design of the three consecutive pha-ses of end-tidal phase reduce the volume of IGTV,CTV and PTV target regions compared with the selection of full-time phase,and have obvious advantages in the planned dosimetry. The irradiation dose that threatens the organs is worthy of being promoted and ap-plied in the large-scale radiotherapy of liver cancer.

Preliminary study in the treatment of lung cancer by using respiratory gating based on four-dimensional CT applied to IGRT / 重庆医学

Objective To explore the preliminary study of the four-dimensional CT-based respiratory gating applications in the IGRT treatment of lung cancer .Methods 38 patients′ were scanned with 4D-CT ,and could got 10 images:0-90% each one ,and then two kinds of radiation treatment plans :Plan-3D and Plan-4D were used ,respectively .Treatment of the patients in the IGRT mode with Plan-4D and following up were done in two months after treatment to evaluate the efficacy and complication probability . Meanwhile evaluation of the two plans by the volume histogram was done .Results The displacement of lung tumor respiratory mo-tion was different in three dimensions ,especially in the Vertical direction ,about(9 .1 ± 2 .2)mm .Accuracy of the distance was 2 .6 mm .The Plan-4D′s CTV was bigger than Plan-3D ,but its PTV was less than the Plan-3D significantly ,at the same time its lung V20 ,MLD were both less than the Plan-3D ,and the difference was statistically significant(P< 0 .05) .The total efficiency(CR+PR)was 77 .78% (28 case);the incidence of 1 ,2 ,3 acute radiation-induced lung injury were 86 .11% ,11 .11% ,2 .78% ,respectively ;the incidence of 1 ,2 acute radiation esophagitis injury were 80 .56% ,8 .33% .Conclusion The respiratory gating techniques based on 4D CT applied in image guided radiotherapy of lung cancer in clinical is feasible ,and it can reduce the volume of the planning tar-get volume ,and help to improve the accuracy of radiotherapy .The degree of respiratory motion is significantly different in individu-als ,and expanding outside the target ranges should be individualized .

Cardiac Magnetic Resonance Imaging Using Multi-physiological Intelligent Trigger System

PURPOSE: We proposed a multi-physiological signals based real-time intelligent triggering system(MITS) for Cardiac MRI. Induced noise of the system was analyzed. MATERIALS AND METHODS: MITS makes cardiac MR imaging sequence synchronize to the cardiac motion using ECG, respiratory signal and second order derivative of SPO2 signal. Abnormal peaks due to arrhythmia or subject's motion are rejected using the average R-R intervals and R-peak values. Induced eddy currents by gradients switching in cardiac MR imaging are analyzed. The induced eddy currents were removed by hardware and software filters. RESULTS: Cardiac MR images that synchronized to the cardiac and respiratory motion are acquired using MITS successfully without artifacts caused by induced eddy currents of gradient switching or subject's motion or arrhythmia. We showed that the second order derivative of the SPO2 signal can be used as a complement to the ECG signals. CONCLUSION: The proposed system performs cardiac and respiratory gating with multi-physiological signals in real time. During the cardiac gating, induced noise caused by eddy currents is removed. False triggers due to subject's motion or arrhythmia are rejected. The cardiac MR imaging with free breathing is obtained using MITS.

Challenges in the delivery of radical radiotherapy for locally advanced non-small cell lung cancer

Locally advanced non-small cell lung cancer (NSCLC) encompasses a heterogeneous collection of tumour and nodal stages. Despite recent advances, the overall survival for this group remains poor. Radical radiotherapy remains the mainstay of treatment. The complexities involved in the delivery of radical radiotherapy to the lung pertain to tumour volume definition, intra- and inter-fraction motion (namely tumour motion caused by respiration and GTV migration during treatment) and the proximity of organs at risk to the high-dose region. Here we discuss a selection of strategies to manage these complexities. Motion management can be addressed by 4D CT planning, radiotherapy gating and on-board imaging, including cone beam CT. Advanced planning methods such as intensity modulated radiotherapy may potentially allow dose escalation and sparing of normal tissue toxicity. Functional imaging has already improved our ability to stage tumours and more carefully select appropriate candidates for radical treatment. Better imaging also improves GTV definition. However, the complexities of image acquisition and interpretation need to be accounted for and agreed consensus protocols have yet to be defined. Novel imaging methods such as 4D PET-CT and 4D MRI may also yield improvements for the future and these are briefly discussed.

Evaluation of the Positional Uncertainty of a Liver Tumor using 4-Dimensional Computed Tomography and Gated Orthogonal Kilovolt Setup Images / 대한방사선종양학회지

PURPOSE: In order to evaluate the positional uncertainty of internal organs during radiation therapy for treatment of liver cancer, we measured differences in inter- and intra-fractional variation of the tumor position and tidal amplitude using 4-dimentional computed radiograph (DCT) images and gated orthogonal setup kilovolt (KV) images taken on every treatment using the on board imaging (OBI) and real time position management (RPM) system. MATERIALS AND METHODS: Twenty consecutive patients who underwent 3-dimensional (3D) conformal radiation therapy for treatment of liver cancer participated in this study. All patients received a 4DCT simulation with an RT16 scanner and an RPM system. Lipiodol, which was updated near the target volume after transarterial chemoembolization or diaphragm was chosen as a surrogate for the evaluation of the position difference of internal organs. Two reference orthogonal (anterior and lateral) digital reconstructed radiograph (DRR) images were generated using CT image sets of 0% and 50% into the respiratory phases. The maximum tidal amplitude of the surrogate was measured from 3D conformal treatment planning. After setting the patient up with laser markings on the skin, orthogonal gated setup images at 50% into the respiratory phase were acquired at each treatment session with OBI and registered on reference DRR images by setting each beam center. Online inter-fractional variation was determined with the surrogate. After adjusting the patient setup error, orthogonal setup images at 0% and 50% into the respiratory phases were obtained and tidal amplitude of the surrogate was measured. Measured tidal amplitude was compared with data from 4DCT. For evaluation of intra-fractional variation, an orthogonal gated setup image at 50% into the respiratory phase was promptly acquired after treatment and compared with the same image taken just before treatment. In addition, a statistical analysis for the quantitative evaluation was performed. RESULTS: Medians of inter-fractional variation for twenty patients were 0.00 cm (range, -0.50 to 0.90 cm), 0.00 cm (range, -2.40 to 1.60 cm), and 0.00 cm (range, -1.10 to 0.50 cm) in the X (transaxial), Y (superior-inferior), and Z (anterior-posterior) directions, respectively. Significant inter-fractional variations over 0.5 cm were observed in four patients. Min addition, the median tidal amplitude differences between 4DCTs and the gated orthogonal setup images were -0.05 cm (range, -0.83 to 0.60 cm), -0.15 cm (range, -2.58 to 1.18 cm), and -0.02 cm (range, -1.37 to 0.59 cm) in the X, Y, and Z directions, respectively. Large differences of over 1 cm were detected in 3 patients in the Y direction, while differences of more than 0.5 but less than 1 cm were observed in 5 patients in Y and Z directions. Median intra-fractional variation was 0.00 cm (range, -0.30 to 0.40 cm), -0.03 cm (range, -1.14 to 0.50 cm), 0.05 cm (range, -0.30 to 0.50 cm) in the X, Y, and Z directions, respectively. Significant intra-fractional variation of over 1 cm was observed in 2 patients in Y direction. CONCLUSION: Gated setup images provided a clear image quality for the detection of organ motion without a motion artifact. Significant intra- and inter-fractional variation and tidal amplitude differences between 4DCT and gated setup images were detected in some patients during the radiation treatment period, and therefore, should be considered when setting up the target margin. Monitoring of positional uncertainty and its adaptive feedback system can enhance the accuracy of treatments.

Efficacy of a Respiratory Training System on the Regularity of Breathing / 대한방사선종양학회지

PURPOSE: In order to enhance the efficiency of respiratory gated 4-dimensional radiation therapy for more regular and stable respiratory period and amplitude, a respiration training system was designed, and its efficacy was evaluated. MATERIALS AND METHODS: The experiment was designed to measure the difference in respiration regularity following the use of a training system. A total of 11 subjects (9 volunteers and 2 patients) were included in the experiments. Three different breathing signals, including free breathing (free-breathing), guided breathing that followed training software (guided-breathing), and free breathing after the guided-breathing (post guided-breathing), were consecutively recorded in each subject. The peak-to-peak (PTP) period of the breathing signal, standard deviation (SD), peak-amplitude and its SD, area of the one cycle of the breathing wave form, and its root mean square (RMS) were measured and computed. RESULTS: The temporal regularity was significantly improved in guided-breathing since the SD of breathing period reduced (free-breathing 0.568 vs guided-breathing 0.344, p=0.0013). The SD of the breathing period representing the post guided-breathing was also reduced, but the difference was not statistically significant (free-breathing 0.568 vs. guided-breathing 0.512, p=ns). Also the SD of measured amplitude was reduced in guided-breathing (free-breathing 1.317 vs. guided-breathing 1.068, p=0.187), although not significant. This indicated that the tidal volume for each breath was kept more even in guided-breathing compared to free-breathing. There was no change in breathing pattern between free-breathing and guided-breathing. The average area of breathing wave form and its RMS in postguided-breathing, however, was reduced by 7% and 5.9%, respectively. CONCLUSION: The guided-breathing was more stable and regular than the other forms of breathing data. Therefore, the developed respiratory training system was effective in improving the temporal regularity and maintaining a more even tidal volume.

Patient Setup Aid with Wireless CCTV System in Radiation Therapy / 대한방사선종양학회지

PURPOSE: To develop a wireless CCTV system in semi-beam's eye view (BEV) to monitor daily patient setup in radiation therapy. MATERIALS AND METHODS: In order to get patient images in semi-BEV, CCTV cameras are installed in a custom-made acrylic applicator below the treatment head of a linear accelerator. The images from the cameras are transmitted via radio frequency signal (~2.4 GHz and 10 mW RF output). An expected problem with this system is radio frequency interference, which is solved utilizing RF shielding with Cu foils and median filtering software. The images are analyzed by our custom-made software. In the software, three anatomical landmarks in the patient surface are indicated by a user, then automatically the 3 dimensional structures are obtained and registered by utilizing a localization procedure consisting mainly of stereo matching algorithm and Gauss-Newton optimization. This algorithm is applied to phantom images to investigate the setup accuracy. Respiratory gating system is also researched with real-time image processing. A line-laser marker projected on a patient's surface is extracted by binary image processing and the breath pattern is calculated and displayed in real-time. RESULTS: More than 80% of the camera noises from the linear accelerator are eliminated by wrapping the camera with copper foils. The accuracy of the localization procedure is found to be on the order of 1.5+/-0.7 mm with a point phantom and sub-millimeters and degrees with a custom-made head/neck phantom. With line-laser marker, real-time respiratory monitoring is possible in the delay time of ~0.17 sec. CONCLUSION: The wireless CCTV camera system is the novel tool which can monitor daily patient setups. The feasibility of respiratory gating system with the wireless CCTV is hopeful.

Development of Conformal Radiotherapy with Respiratory Gate Device / 대한방사선종양학회지

PURPOSE: 3D conformal radiotherapy, the optimum dose delivered to the tumor and provided the risk of normal tissue unless marginal miss, was restricted by organ motion. For tumors in the thorax and abdomen, the planning target volume (PTV) is decided including the margin for movement of tumor volumes during treatment due to patients breathing. We designed the respiratory gating radiotherapy device (RGRD) for using during CT simulation, dose planning and beam delivery at identical breathing period conditions. Using RGRD, reducing the treatment margin for organ (thorax or abdomen) motion due to breathing and improve dose distribution for 3D conformal radiotherapy. MATERIALS AND METHODS: The internal organ motion data for lung cancer patients were obtained by examining the diaphragm in the supine position to find the position dependency. We made a respiratory gating radiotherapy device (RGRD) that is composed of a strip band, drug sensor, micro switch, and a connected on-off switch in a LINAC control box. During same breathing period by RGRD, spiral CT scan, virtual simulation, and 3D dose planing for lung cancer patients were performed, without an extended PTV margin for free breathing, and then the dose was delivered at the same positions. We calculated effective volumes and normal tissue complication probabilities (NTCP) using dose volume histograms for normal lung, and analyzed changes in doses associated with selected NTCP levels and tumor control probabilities (TCP) at these new dose levels. The effects of 3D conformal radiotherapy by RGRD were evaluated with DVH (Dose Volume Histogram), TCP, NTCP and dose statistics. RESULTS: The average movement of a diaphragm was 1.5 cm in the supine position when patients breathed freely. Depending on the location of the tumor, the magnitude of the PTV margin needs to be extended from 1 cm to 3 cm, which can greatly increase normal tissue irradiation, and hence, results in increase of the normal tissue complications probability. Simple and precise RGRD is very easy to setup on patients and is sensitive to length variation (+2 mm), it also delivers on-off information to patients and the LINAC machine. We evaluated the treatment plans of patients who had received conformal partial organ lung irradiation for the treatment of thorax malignancies. Using RGRD, the PTV margin by free breathing can be reduced about 2 cm for moving organs by breathing. TCP values are almost the same values (4-5% increased) for lung cancer regardless of increasing the PTV margin to 2.0 cm but NTCP values are rapidly increased (60-70% increased) for upon extending PTV margins by 2.0 cm. CONCLUSION: Internal organ motion due to breathing can be reduced effectively using our simple RGRD. This method can be used in clinical treatments to reduce organ motion induced margin, thereby reducing normal tissue irradiation. Using treatment planning software, the dose to normal tissues was analyzed by comparing dose statistics with and without RGRD. Potential benefits of radiotherapy derived from reduction or elimination of planning target volume (PTV) margins associated with patient breathing through the evaluation of the lung cancer patients treated with 3D conformal radiotherapy.