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@#<b>Objective</b> To compare the effects of different respiratory signal acquisition methods on the delineation of moving tumor targets. <b>Methods</b> A cube phantom containing a sphere was placed on a motion platform to simulate respiratory movement by setting motion period, frequency, and direction. Respiratory signal was acquired by real-time position management (RPM) method and GE method independently. Target delineation was conducted using the maximum intensity projection (MIP) sequence. The difference between the reconstructed volume and the theoretical moving volume was compared under the two respiratory signal acquisition methods for cube and sphere targets. <b>Results</b> Under the same respiratory signal acquisition method, the same respiratory amplitude, and different respiratory frequencies, reconstructed volume changes were relatively small. For the sphere target, the deviation between the reconstructed volume and the theoretical moving volume was −1.5% to 5.7% with the RPM method and −1.3% to −13.8% with the GE method (both <i>P</i> < 0.05). For the cube target, the deviation between the reconstructed volume and the theoretical moving volume was 0.2% to 0.9% with the RPM method and −2.6% to 0.9% with the GE method, with no statistical significance. <b>Conclusion</b> For small-volume sphere targets, the target volumes obtained from MIP images by the two respiratory signal acquisition methods are both smaller than the actual moving volume. For large-volume cube targets, there is no significant difference between the reconstructed and theoretical results with any respiratory signal acquisition method. The RPM method produces smaller deviation and better image quality when reconstructing small-volume targets.
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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.
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In pediatric thoracic CT, respiratory motion is generally treated as a motion artifact degrading the image quality. Conversely, respiratory motion in the thorax can be used to answer important clinical questions, that cannot be assessed adequately via conventional static thoracic CT, by utilizing four-dimensional (4D) CT. However, clinical experiences of 4D thoracic CT are quite limited. In order to use 4D thoracic CT properly, imagers should understand imaging techniques, radiation dose optimization methods, and normal as well as typical abnormal imaging appearances. In this article, the imaging techniques of pediatric thoracic 4D CT are reviewed with an emphasis on radiation dose. In addition, several clinical applications of pediatric 4D thoracic CT are addressed in various thoracic functional abnormalities, including upper airway obstruction, tracheobronchomalacia, pulmonary air trapping, abnormal diaphragmatic motion, and tumor invasion. One may further explore the clinical usefulness of 4D thoracic CT in free-breathing children, which can enrich one's clinical practice.
Subject(s)
Child , Humans , Airway Obstruction , Artifacts , Four-Dimensional Computed Tomography , Thorax , Tomography, X-Ray Computed , TracheobronchomalaciaABSTRACT
OBJECTIVE: To evaluate the technical feasibility of four-dimensional (4D) CT for the functional evaluation of the pediatric diaphragm. MATERIALS AND METHODS: In 22 consecutive children (median age 3.5 months, age range 3 days–3 years), 4D CT was performed to assess diaphragm motion. Diaphragm abnormalities were qualitatively evaluated and diaphragm motion was quantitatively measured on 4D CT. Lung density changes between peak inspiration and expiration were measured in the basal lung parenchyma. The diaphragm motions and lung density changes measured on 4D CT were compared between various diaphragm conditions. In 11 of the 22 children, chest sonography was available for comparison. RESULTS: Four-dimensional CT demonstrated normal diaphragm (n = 8), paralysis (n = 10), eventration (n = 3), and diffusely decreased motion (n = 1). Chest sonography demonstrated normal diaphragm (n = 2), paralysis (n = 6), eventration (n = 2), and right pleural effusion (n = 1). The sonographic findings were concordant with the 4D CT findings in 90.9% (10/11) of the patients. In diaphragm paralysis, the affected diaphragm motion was significantly decreased compared with the contralateral normal diaphragm motion (−1.1 ± 2.2 mm vs. 7.6 ± 3.8 mm, p = 0.005). The normal diaphragms showed significantly greater motion than the paralyzed diaphragms (4.5 ± 2.1 mm vs. −1.1 ± 2.2 mm, p < 0.0001), while the normal diaphragm motion was significantly smaller than the motion of the contralateral normal diaphragm in paralysis (4.5 ± 2.1 mm vs. 7.6 ± 3.8 mm, p = 0.01). Basal lung density change of the affected side was significantly smaller than that of the contralateral side in diaphragm paralysis (89 ± 73 Hounsfield units [HU] vs. 180 ± 71 HU, p = 0.03), while no significant differences were found between the normal diaphragms and the paralyzed diaphragms (136 ± 66 HU vs. 89 ± 73 HU, p = 0.1) or between the normal diaphragms and the contralateral normal diaphragms in paralysis (136 ± 66 HU vs. 180 ± 71 HU, p = 0.1). CONCLUSION: The functional evaluation of the pediatric diaphragm is feasible with 4D CT in select children.
Subject(s)
Child , Humans , Diaphragm , Diaphragmatic Eventration , Four-Dimensional Computed Tomography , Lung , Paralysis , Pleural Effusion , Thorax , UltrasonographyABSTRACT
@#BACKGROUND: The limbe is a traditional Mongolian instrument that has been used since the ancient times, and the performer uses a unique method called circular breathing to play it. The circular breathing technique is significant heritage of the Mongolian people, and has been recognized by UNESCO World Heritage. Aim: To study the anatomy and physiology that take part in playing the Mongolian limbe with the circular breathing technique. METHODS: We have studied 20 flutists using case control study method. The flutists’ change of gas compound in blood have been studied with a gas analyzer after playing for 10 minutes with the circular breathing. When the flutists play it with circular breathing, the anatomical structures and their function have been studied and documented by an endoscopy, X-ray and a 320 row area detector CT. RESULTS: The 20 participants were between the ages of 22-56 with the circular breathing experience of 2 to 37 years. After playing the instrument for 10 minutes, we found the following results: 67.7% of the participants developed alkolosis, 23.5% hypocapnia, 5.9% hypercapnia, 94.1% hypoxia, and all participants’ oxygen saturation decreased. The lingual muscles, upper and under muscles of the hyoid bone, larynx and vocal cords are the main structures of the circular breathing. CONCLUSION: Playing Mongolian limbe with the circular breathing leads to hypoxia, thus the circular breathing stops. It is important to note that this process does not depend on flutist’s age, their practice time, and their personal technique. However, we concluded that the time of performance without interruption depends on individual’s physiological characteristics. In order to study the issues of anatomy and physiology that take part in playing the Mongolian limbe with the circular breathing, we have studied 20 flutists using case control study method. The flutists’ change of gas compound in blood have been studied with a gas analyzer after playing 10 minutes by the circular breathing. When the flutists play it with circular breathing, the anatomical structures and their function have been studied and documented by an endoscopy and X-ray. The lingual muscles, upper and under muscles of the hyoid bone, larynx and vocal cords take part in the circular breathing by limbe as a main rule. Playing Mongolian limbe with the circular breathing lead to hypoxia thus the circular breathing stops. This process does not depend on flutist’s age, their practice time, and their private technique. But we concluded that how long time they play it without interruption depends on individual’s physiological singularity.
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Objective To investigate the difference of lung and target volume and dosimetry characteristics features of deep inhalation breathing holding-active breathing control (ABC) and the four dimensional CT (4D-CT) free breathing in stereotactic body radiation therapy (SBRT) technology for patients with lung cancer.Methods 10 patients with pulmonary malignant tumor who were proposed SBRT treatment were selected,and received CT under free breath (FB-CT),4D-CT scan under quiet respiration (4D-CT) and active breathing control CT scan (ABC-CT),respectively.With SBRT technology under the same condition designed four corresponding plans,FB-CT,ABC-CT,4D-CT and 4D-CT0 which was the end inspiratory phase of 4D-CT respectively.The lung volume(V),PTV,V5,V20,mean lung dose(MLD) and normal tissue complication probability(NTCP) of four treatment programs were counted and compared.Results Compared with FB-CT,V,PTV,V5,V20,MLD and NTCP of ABC-CT were 51.48％,-65.34％,-42.64％,-56.62％,-40.22％ and-98.53％ (t=-7.14 to6.16,P＜0.05);PTV,V5,V20,MLD and NTCP of 4D-CT were-40.14％,-16.90％,-37.16％,-17.85％ and-90.96％ (t =0.54 to 3.22,P＜0.05);PTV,V5,V20,MLD and NTCP of 4D-CT0 were-68.98％,-30.21％,-48.49％,-37.45％ and-95.82％ (t=1.32 to 5.46,P＜0.05),respectively.Compared with FB-CT,the lung volume of 4D-CT and 4D-CT0 had no statistical difference (P ＞ 0.05).Conclusions ABC-CT methods have ideal clinical characteristics,with larger double lung volume,smaller artifacts of image,and higher target matching precision.ABC-CT methods reduce the dose of normal lung tissues significantly.
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Objective To evaluate the impact of respiratory motion on lung dosimetry using 4D-CT during lung cancer radiotherapy.Methods Ten cases were randomly selected from non-small cell lung cancer (NSCLC) patients treated in our department.The 4D-CT machine was adopted for simulation before treatment and 10 respiratory phases were obtained for each patient.Target volumes were delineated on the maximum intensity projection (MIP) images,and plans were generated on average intensity projection (ALP) images.Plans were transferred to CT images of each respiratory phase,and we calculated the dosage on lungs and subsequently evaluated the volume dosage to lungs and the entire body.Results The mean dosage to lungs are greatly affected by the respiratory phase.This difference also depended on tumor location.When it was inside the lung,the average dosage shows the same trend as the respiratory motion,with the change rate of 2.18％,which was less than the change of lung volume 4.49％ (t =4.189,P ＜ 0.05).When the tumor was located nearby the lung,the mean dosage showed the opposite trend with respiratory motion,with the change rate of 3.76％,which was also less than the change of lung volume 4.49％ (t =25.007,P ＜ 0.05).The effect of respiratory motion on V5,V10,V20 of body was small,and the magnitude of change for whole body dosages were 0.47％,0.28％,0.17％ respectively,which was smaller than the change of lung volume 4.49％ (t =11.371,11.188,11.377,P ＜ 0.05).Volume dose of lung V5,V10,V20 and lung volume change trends were the same,and the magnitude of change for lung volume dosages were 2.39％,1.91％,1.80％ respectively,and were smaller than the change of lung volume 4.49％ (t =2.279,2.298,2.485,P ＜ 0.05).Conclusions The mean dosage to lungs shows a great difference between different respiratory phases.More attention should be paid when evaluating the lung volume during treatment planning.
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Objective To explore the effect of respiration on dose accumulation for target volume and normal liver in radiotherapy for hepatocellular carcinoma (HCC) while applying 4D-CT and deformable registration.Methods Nineteen HCC patients who had received transcatheter arterial chemoembolization were enrolled in this study.All patients underwent 3D-and 4D-CT simulation in free breathing.The 3D dose (Dose-3D) was calculated from the treatment planning designed on the 3D-CT image.The Dose-3D then was recalculated on ten phases of 4D-CT images respectively,and the end-inspiration and end-expiration doses were defined as Dose El and Dose-EE.The 4D dose (Dose-4D) was obtained by deforming and accumulating ten-phase doses of 4D-CT images on the end-expiration phase image.The dosimetric differences of planning target volume and normal liver were compared among Dose-3D,Dose-4D,Dose-EI and Dose-EE.Results The D99 and D95of planning target volume (PTV) in Dose-3D were higher than those of Dose-4D,Dose-Fl and Dose EE (x2 =32.75,26.31,P ＜ 0.05).The conformal index (CI) and homogeneity index (HI) in Dose-3D were better than those of Dose-4D,Dose-E1 and Dose-EE,in which CI decreased from 0.78 to0.63,0.60 and 0.57,while HI increased from 0.08 to 0.15,0.16 and 0.19 (x2 =37.80,31.86,P ＜0.05).No statistically significant differences were found in dosimetric indices of PTV between Dose-4D and Dose EI,Dose-EE,and between Dose-El and Dose-EE (P ＞ 0.05).The mean dose (D),V5,V10,V20,V30 and V40 of normal liver were similar among four dose distributions (P ＞ 0.05).Conclusions More objective and precise dose distribution for target volume and normal liver could be obtained by applying both 4D-CT and deformable registration,which is beneficial to accurately predicting the dosevolume indices of radiation-induced liver injury and offering more reliable evidence of escalation for target dose.
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The purpose of this study was to develop the respiratory training system using individual characteristic guiding waveform to reduce the impact of respiratory motion that causes artifact in radiotherapy. In order to evaluate the improvement of respiratory regularity, 5 volunteers were included and their respiratory signals were acquired using the in-house developed belt-type sensor. Respiratory training system needs 10 free breathing cycles of each volunteer to make individual characteristic guiding waveform based on Fourier series and it guides patient's next breathing. For each volunteer, free breathing and guided breathing which uses individual characteristic guiding waveform were performed to acquire the respiratory cycles for 3 min. The root mean square error (RMSE) was computed to analyze improvement of respiratory regularity in period and displacement. It was found that respiratory regularity was improved by using respiratory training system. RMSE of guided breathing decreased up to 40% in displacement and 76% in period compared with free breathing. In conclusion, since the guiding waveform was easy to follow for the volunteers, the respiratory regularity was significantly improved by using in-house developed respiratory training system. So it would be helpful to improve accuracy and efficiency during 4D-RT, 4D-CT.
Subject(s)
Artifacts , Displacement, Psychological , Fourier Analysis , RespirationABSTRACT
In this study, we evaluated feasibility of applying MTV (Metabolic Target Volume) to respiratory gated radiotherapy for more accurate treatment using various SUV (Standard Uptake Value) from PET images. We compared VOI (Volume of Interest) images from 50%, 30% and 5% SUV (standard uptake volume) from PET scan of an artificial target with GTV (Gross Tumor Volume) images defined by percentage of respiratory phase from 4D-CT scan for respiratory gated radiotherapy. It is found that the difference of VOI of 30% SUV is reduced noticeably comparing with that of 50% SUV in longitudinal direction with respect to total GTV of 4D-CT image. Difference of VOI of 30% SUV from 4D-PET image defined by respiratory phase from 25% inhalation to 25% exhalation, and GTV from 4D-CT with the same phase is shown below 0.6 cm in maximum. Thus, it is better to use 4D-PET images than conventional PET images for applying MTV to gated RT. From the result that VOI of 5% SUV from 4D-PET agrees well with reference image of 4D-CT in all direction, and the recommendation from department of nuclear medicine that 30% SUV be advised for defining tumor range, it is found that using less than 30% SUV will be more accurate and practical to apply MTV for respiratory gated radiotherapy.
Subject(s)
Exhalation , Inhalation , Nuclear Medicine , Positron-Emission TomographyABSTRACT
PURPOSE : To assess the respiratory tumor movement using 4D-CT (4-dimensional computed tomography) for minimizing setup and target volume uncertainty of body-frame based stereotactic radiosurgery (SRS) in lung tumor. MATERIALS AND METHODS : Fifty-seven stereotactic radiation therapies with respiratory gating system in 44 patients (two targets in seven patients and three in three patients) were executed in Asan Medical Center from May 2005 to June 2006. We used respiratory gating system consisted of RPM (Real-time Positioning Management system, Varian, USA) and 4D-CT (GE healthcare, USA), if tumor movement was exceeding 5 mm by respiration on fluoroscopy. Accurate tumor movement on reconstructed 4D-CT image was determined for respiratory gated therapy. Respiratory gated therapy was done if tumor movement was exceeding 5 mm, and non-gated therapy was done if it was below 5 mm. RESULTS : Forty-five tumors were treated with supine position, and the other twelve were with prone position. Median tumor movement (3-dimensional) by respiration was 8.78+/-5.30 mm, and it was mostly affected by superior-inferior movement (8.53+/-5.23 mm). Tumor movements were different by tumor location, whether upper (5.38+/-2.85 mm) or lower (10.12+/-5.08 mm) lobe (p=0.015). Tumor movement was exceeding 5 mm in 27 (47.3%) tumors, and below 5 mm in 30 tumors in 4D-CT evaluation. Tumor movements on adopted respiratory gated phase were wholly below 5 mm, and its median value was 3.70+/-1.13 mm. CONCLUSION : Assessment of respiratory tumor movement using 4D-CT and gating system was helpful for minimizing target volume uncertainty. As a result, image-guided radiation therapy could improve the treatment accuracy of high precision stereotactic radiosurgery
Subject(s)
Humans , Delivery of Health Care , Fluoroscopy , Four-Dimensional Computed Tomography , Lung , Prone Position , Radiosurgery , Radiotherapy, Image-Guided , Respiration , Supine Position , UncertaintyABSTRACT
For Stereotactic Radiosurgery of lung tumor, 4 dimensional CT was done during for free breathing of the patient. The movement of the treated target was measured in the CT images, and appropriate breathing cycle was selected for treatment. For patient A, the movement of the treatment target was 10.1 mm during full breathing cycle, and 5.4 mm for treated breathing cycle, 30~70%. For patient B, the movement was 13 mm, and 3.5 mm for full breathing cycle and treated breathing cycle, respectively.
Subject(s)
Humans , Four-Dimensional Computed Tomography , Lung Neoplasms , Lung , Radiosurgery , RespirationABSTRACT
PURPOSE: Reduction of respiratory motion artifacts in PET images was studied using respiratory-gated PET (RGPET) with moving phantom. Especially a method of generating simulated helical CT images from 4D-CT datasets was developed and applied to a respiratory specific RGPET images for more accurate attenuation correction. MATERIALS AND METHODS: Using a motion phantom with periodicity of 6 seconds and linear motion amplitude of 26 mm, PET/CT (Discovery ST; GEMS) scans with and without respiratory gating were obtained for one syringe and two vials with each volume of 3, 10, and 30 ml respectively. RPM (Real-Time Position Management, Varian) was used for tracking motion during PET/CT scanning. Ten datasets of RGPET and 4D-CT corresponding to every 10% phase intervals were acquired. From the positions, sizes, and uptake values of each subject on the resultant phase specific PET and CT datasets, the correlations between motion artifacts in PET and CT images and the size of motion relative to the size of subject were analyzed. RESULTS: The center positions of three vials in RGPET and 4D-CT agree well with the actual position within the estimated error. However, volumes of subjects in non-gated PET images increase proportional to relative motion size and were overestimated as much as 250% when the motion amplitude was increased two times larger than the size of the subject. On the contrary, the corresponding maximal uptake value was reduced to about 50%. CONCLUSION: RGPET is demonstrated to remove respiratory motion artifacts in PET imaging, and moreover, more precise image fusion and more accurate attenuation correction is possible by combining with 4D-CT.