Correlation Between Bladder Volume and Irradiated Dose of Small Bowel in CT-based Planning of Intracavitary Brachytherapy for Cervical Cancer

To quantify the effect of bladder volume on the dose distribution of intracavitary brachytherapy in computed tomography-based treatment planning for cervical cancer. Ten patients with cervical cancer were treated with high-dose rate radiation brachytherapy. For the three-dimensional analysis, pelvic computed tomographic scans were obtained from patients with indwelling catheters in place and from patients who received 50, 100, 150 and 200 cc injections of sterile water into their bladders ('200 cc' was defined as a full bladder). Additionally, scans were made in the prone position with the full bladder. Bladder fullness significantly affected the dose to the small bowel and bladder. The median of maximal doses to the small bowel was significantly greater with an empty bladder in all factors of hot spot (480 vs. 256 cGy on D-2cc). Although dosimetry revealed lower doses for larger volumes of bladder (D-50 and V-25%), the median maximal dose to the bladder was significantly greater with a full bladder (420 vs. 775 cGy on D-2cc). The rectosigmoid doses were not affected by bladder distension (476 vs. 467 cGy on D-2cc). After changing to the prone position, the hot spot dose of small bowel did not change but that of the bladder significantly decreased, although this procedure was very difficult. An increase in bladder volume resulted in a significant reduction in the hot spot dose of the small bowel at the expense of an increase in that of the bladder without changing the dose distribution of the rectosigmoid.


4D digitally reconstructed radiography for verifying a lung tumor position during volumetric modulated arc therapy

We have proposed four dimensional (4D) digitally reconstructed radiography (DRR) for verifying a lung tumor position during volumetric modulated arc therapy (VMAT). An internal target volume (ITV) was defined based on two clinical target volumes (CTVs) delineated on maximum exhalation and maximum inhalation images acquired by 4D planning computed tomography (CT). A planning target volume (PTV) was defined by adding a margin of 5 mm to the ITV on the maximum exhalation 3D CT images. A single-arc VMAT plan was created on the same CT data using Pinnacle SmartArc with a maximum multi-leaf collimator leaf speed of 1 mm/degree, thereby resulting in quasi-conformal field shapes while optimizing each beam intensity for each gantry angle. During VMAT delivery, cone-beam CT (CBCT) projection data were acquired by an on-board kilovoltage X-ray unit and a flat panel 2D detector. Four CBCT image sets with different respiratory phases were reconstructed using in-house software, where respiratory phases were extracted from the projection data. Subsequently a CTV was delineated on each of the 4D CBCT images by an oncologist. Using the resulting 4D CBCT data including the CTV contours, 4D DRRs during the VMAT delivery were calculated as a function of gantry angle. It was confirmed that the contoured CTV was within the radiation field during the four-fraction lung VMAT delivery. The proposed 4D DRR may facilitate the verification of the position of a respiratory moving lung tumor during VMAT delivery on each treatment day.


Single-Arc Volumetric Modulated Arc Therapy Planning for Left Breast Cancer and Regional Nodes

We have successfully created a single arc volumetric modulated arc therapy (VMAT) plan for treating post-surgical left breast/chest wall and regional nodes using Elekta multileaf collimator (MLC). Dose volume histograms (DVHs) were compared between the VMAT plans and conventional tangential beam plans using a field-in-field technique, leading to significant DVH advantages in the VMAT plans. The difference between Elekta VMAT and Varian RapidArc due to different MLC designs was discussed in terms of the number of arcs required to cover a large target, highlighting a single arc capability of Elekta VMAT for a large target volume which may be less sensitive to unexpected organ motion during dose delivery.


4D-CBCT reconstruction using MV portal imaging during volumetric modulated arc therapy

Recording target motion during treatment is important for verifying the irradiated region. Recently, cone-beam computed tomography (CBCT) reconstruction from portal images acquired during volumetric modulated arc therapy (VMAT), known as VMAT-CBCT, has been investigated. In this study, we developed a four-dimensional (4D) version of the VMAT-CBCT. The MV portal images were sequentially acquired from an electronic portal imaging device. The flex, background, monitor unit, field size, and multi-leaf collimator masking corrections were considered during image reconstruction. A 4D VMAT-CBCT requires a respiratory signal during image acquisition. An image-based phase recognition (IBPR) method was performed using normalised cross correlation to extract a respiratory signal from the series of portal images. Our original IBPR method enabled us to reconstruct 4D VMAT-CBCT with no external devices. We confirmed that 4D VMAT-CBCT was feasible for two patients and in good agreement with in-treatment 4D kV-CBCT. The visibility of the anatomy in 4D VMAT-CBCT reconstruction for lung cancer patients has the potential of using 4D VMAT-CBCT as a tool for verifying relative positions of tumour for each respiratory phase.


Rib Cage Motion Model Construction Based on Patient-Specific CT Images Between Inhalation and Exhalation

呼気および吸気時CT画像に基づく胸郭運動モデルの構築

It is important to estimate rib cage motion quantitatively because lung deformation is caused by motion of the rib cage and diaphragm. In this paper, a patient-specific model of rib cage motion between inhalation and exhalation is proposed based on anatomical knowledge and rib cage kinematics. Time-series geometric changes in the patient-specific 3D rib cage configuration (including the ribs, spine, and sternum), which is segmented based on exhalation CT images, can be simulated using the proposed method. In addition, the validity of the proposed rib cage motion model was evaluated using inhalation and exhalation CT images.

胸郭の運動が一因となり呼吸による肺変形が引き起こされるため，胸郭の時系列の動きを知ることは肺内部の変形シミュレーションをする際に重要な知見となる．そこで，解剖学的知見とCT画像をともに用いる胸郭運動モデルを提案する．肋骨は肋横突関節と肋椎関節を結ぶ軸で回転運動をさせ，各肋骨の回転角度は呼気と吸気時のCT画像から求める．これにより，提案した胸郭運動モデルがポンプハンドル運動とバケットハンドル運動を定性的に再現できることを示す．さらに，呼気と吸気時のCT画像を用いて，提案した胸郭運動モデルにおける肋骨の回転角度算出手法の妥当性を検証する．


Four-Dimensional Measurement of the Displacement of Internal Fiducial Markers During 320-Multislice Computed Tomography Scanning of Thoracic Esophageal Cancer

To investigate the three-dimensional movement of internal fiducial markers placed near esophageal cancers using 320-multislice CT. This study examined 22 metal markers in the esophageal wall near the primary tumors of 12 patients treated with external-beam photon radiotherapy. Motion assessment was analyzed in 41 respiratory phases during 20 s of cine CT in the radiotherapy position. Motion in the cranial-caudal (CC) direction showed a strong correlation (R(2) > 0.4) with the respiratory curve in most markers (73%). The average absolute amplitude of the marker movement was 1.5 ± 1.6 mm, 1.6 ± 1.7 mm, and 3.3 ± 3.3 mm in the left-right (LR), anterior-posterior (AP), and CC directions, respectively. The average marker displacements in the CC direction between peak exhalation and inhalation for the 22 clips were 1.1 mm (maximum, 5.5 mm), 3.0 mm (14.5 mm), and 5.1 mm (16.3 mm) for the upper, middle, and lower thoracic esophagus, respectively. Motion in primary esophagus tumor was evaluated with 320-multislice CT. According to this study, 4.3 mm CC, 1.5 mm AP, and 2.0 mm LR in the upper, 7.4 mm CC, 3.0 mm AP, and 2.4 mm LR in the middle, and 13.8 mm CC, 6.6 mm AP, and 6.8 mm LR in the lower thoracic esophagus provided coverage of tumor motion in 95% of the cases in our study population.

International Journal of Radiation Oncology*Biology*Physics


First In-situ Dose Calculation Report Using In-treatment Kilovoltage Cone-beam CT and In-treatment Linac Parameters during Volumetric Modulated Arc Therapy


Motion Analysis of Target in Stereotactic Radiotherapy of Lung Tumors Using 320-row Multidetector CT

320列CT装置を用いた肺定位放射線治療における標的の軌跡解析

Multi-detector computed tomography (MDCT) has rapidly evolved and is increasingly used for treatment simulation of thoracic and abdominal radiotherapy. A 320-detector row CT scanner has recently become available that allows axial volumetric scanning of a 16-cm-long range in a patient without table movement. Current radiotherapy techniques require a generous margin around the presumed gross tumor volume (GTV) to account for uncertainties such as tumor motion and set up error. Motion analysis is useful to evaluate the internal margin of a moving target due to respiration and to improve therapeutic precision. The purpose of this study is to propose a method using phase-only correlation to automatically detect the target and to assess the motion of the target in numerical phantoms and patients. Free-breathing scans using 320-detector row CT were acquired for 4 patients with lung tumor(s). The proposed method was feasible for motion analysis of all numerical phantoms and patients. The results reproduced the facts that the motion of tumors in the patients varied in orbits during the respiratory cycle and exhibited hysteresis. The maximum distance between peak exhalation and inhalation increased as the tumors approached the diaphragm. The proposed method detected the three-dimensional position of the targets automatically and analyzed the trajectories. The tumor motion due to respiration differed by region and was greatest for the lower lobe.

Japanese Journal of Radiological Technology


Cone Beam Computed Tomography Data Acquisition during VMAT Delivery with Subsequent Respiratory Phase Sorting Based on Projection Image Cross-correlation


Generation Method for Simulation-based Chest 4DCT Based on Particle Simulation for Radiotherapy

放射線治療のための粒子法シミュレーションに基づく胸部Simulation-based 4DCTの構成

In current standard radiotherapy of lung cancer, an excessive volume of normal tissues may be irradiated due to respiratory displacement. If the motion of the lungs could be predicted by computer simulation, radiation exposure to normal tissues could be reduced. Lung deformation is modeled as an elastic material. The lung model is created automatically from computed tomography (CT) images using binarization, mathematical morphology, and region growing. The effects of abdominal breathing and pleural sliding are incorporated into the boundary conditions by template matching between CT images acquired during the inhalation and exhalation phases. Lung motion is then predicted using the moving particle simulation (MPS) method. Since CT images are required for radiotherapy planning, we propose a generation method for simulation-based 4DCT equivalent to actual 4DCT using CT images acquired during the inhalation and exhalation phases and particle simulation results obtained using the image warping technique.

通常の胸部放射線治療においては呼吸性移動による範囲を網羅するような広めの照射範囲を設定するため，正常組織にも多量の放射線が照射されてしまう可能性がある．そこで，生体力学シミュレーションにより肺内部の動きを予測できれば，正常組織の被曝を低減できる．本研究では吸気時CT画像から3次元肺形状を作成し，弾性体であるとモデル化して粒子法により肺内部の動きをシミュレーションする．シミュレーションの境界条件には呼気時および吸気時のCT画像からTemplate Matchingを用いて横隔膜および肺野輪郭の移動量を算出したものを用いる．そして，シミュレーション結果と呼気時および吸気時のCT画像から4DCT相当の時系列3DCT画像をImage Warpingを用いて構成する．


Prescreening based on the presence of CT-scan abnormalities and biomarkers (KL-6 and SP-D) may reduce severe radiation pneumonitis after stereotactic radiotherapy

To determine the risk factors of severe radiation pneumonitis (RP) after stereotactic body radiation therapy (SBRT) for primary or secondary lung tumors. From January 2003 to March 2009, SBRT was performed on 117 patients (32 patients before 2005 and 85 patients after 2006) with lung tumors (primary = 74 patients and metastatic/recurrent = 43 patients) in our institution. In the current study, the results on cases with severe RP (grades 4-5) were evaluated. Serum Krebs von den Lungen-6 (KL-6) and serum Surfactant protein-D (SP-D) were used to predict the incidence of RP. A shadow of interstitial pneumonitis (IP) on the CT image before performing SBRT was also used as an indicator for RP. Since 2006, patients have been prescreened for biological markers (KL-6 & SP-D) as well as checking for an IP-shadow in CT. Grades 4-5 RP was observed in nine patients (7.7%) after SBRT and seven of these cases (6.0%) were grade 5 in our institution. A correlation was found between the incidence of RP and higher serum KL-6 & SP-D levels. IP-shadow in patient's CT was also found to correlate well with the severe RP. Severe RP was reduced from 18.8% before 2005 to 3.5% after 2006 (p = 0.042). There was no correlation between the dose volume histogram parameters and these severe RP patients. Patients presenting with an IP shadow in the CT and a high value of the serum KL-6 & SP-D before SBRT treatment developed severe radiation pneumonitis at a high rate. The reduction of RP incidence in patients treated after 2006 may have been attributed to prescreening of the patients. Therefore, pre-screening before SBRT for an IP shadow in CT and serum KL-6 & SP-D is recommended in the management and treatment of patients with primary or secondary lung tumors.


Particle Simulation of Lung Deformation in Axial Plane by Chest Respiration and Heartbeat

胸式呼吸と心拍動による肺野変形のAxial面における粒子法シミュレーション

Transaction of the Japan Society for Simulation Technology

日本シミュレーション学会論文誌


Patient setup error and day-to-day esophageal motion error analyzed by cone-beam computed tomography in radiation therapy

Little has been reported on the errors of setup and daily organ motion that occur during radiation therapy (RT) for esophageal cancer. The purpose of this paper was to determine the margins of esophageal motion during RT. The shift of the esophagus was analyzed in 20 consecutive patients treated with RT for esophageal cancer from November 2007. CT images for RT planning were used as the primary image series. Computed tomography (CT) images were acquired using an Elekta Synergy System, equipped with a kilovoltage-based cone-beam CT (CBCT) unit. The subsequent CBCT image series used for daily RT setup were compared with the primary image series to analyze esophageal motion. CBCT was performed before treatment sessions a total of 10 times in each patient twice a week. The outer esophageal wall was contoured on the CBCT images of all 200 sets. In the 200 sets of CBCT images, the mean (absolute) +/- standard deviation (SD) of setup errors were 2 +/- 2 mm (max, 8 mm) in the lateral direction, 4 +/- 3 mm (max, 11 mm) in the longitudinal direction, and 4 +/- 3 mm (max, 13 mm) in the vertical direction. Additionally, the mean +/- SD values of daily esophageal motion comparing the CBCT with RT planning CT were 5 +/- 3 mm (max, 15 mm) in the lateral direction and 5 +/- 3 mm (max, 15 mm) in the vertical direction. Our data support the use of target margins (between the clinical target volume and planning target volume) of 9 mm for day-to-day esophageal motion and 8 mm for patient setup in all directions, respectively.


First report on prostate displacements immediately before and after treatment relative to the position during VMAT delivery


Quality assurance of volumetric modulated arc therapy using Elekta Synergy

PURPOSE. Recently, Elekta has supplied volumetric modulated arc therapy (VMAT) in which multi-leaf collimator (MLC) shape, jaw position, collimator angle, and gantry speed vary continuously during gantry rotation. A quality assurance procedure for VMAT delivery is described. METHODS AND MATERIALS. A single-arc VMAT plan with 73 control points (CPs) and 5-degree gantry angle spacing for a prostate cancer patient has been created by ERGO + + treatment planning system (TPS), where MLC shapes are given by anatomic relationship between a target and organs at risk and the monitor unit for each CP is optimized based on given dose prescriptions. Actual leaf and jaw positions, gantry angles and dose rates during prostate VMAT delivery were recorded in every 0.25 seconds, and the errors between planned and actual values were evaluated. The dose re-calculation using these recorded data has been performed and compared with the original TPS plan using the gamma index. RESULTS. Typical peak errors of gantry angles, leaf positions, and jaw positions were 3 degrees, 0.6 mm, and 1 mm, respectively. The dose distribution obtained by the TPS plan and the recalculated one agreed well under 2%-2 mm gamma index criteria. CONCLUSIONS. Quality assurance for prostate VMAT delivery has been performed with a satisfied result.


Contrast media-assisted visualization of brain metastases by kilovoltage cone-beam CT


First clinical cone-beam CT imaging during volumetric modulated arc therapy


Spontaneous chiral symmetry breaking in the massless linear sigma model by Fermion and Boson loop corrections


Reanalysis of muonic 90 Zr and 208 Pb atoms


Electron gun using carbon-nanofiber field emitter


Self-consistent relativistic random-phase approximation with vacuum polarization


Relativistic Hartree approach with exact treatment of vacuum polarization for finite nuclei


Relativistic random-phase approximation calculation with negative energy states of nuclear polarization in muonic atoms


New field-emission x-ray radiography system


Hyperfine splitting of hydrogenlike atoms based on relativistic mean field theory


Gauge invariant evaluation of nuclear polarization with the collective model


Physical Review A, Atomic, Molecular, and Optical Physics


Nuclear polarization in hydrogenlike 20882Pb81+


Nuclear polarization in hydrogenlike heavy ions


Evaluation of Blood Flow and Plaque Vulnerability in Carotid Artery Stenosis Focusing on Morphological and Component Characteristics

Proceedings of the 2022 ISMRM & SMRT ANNUAL MEETING & EXHIBITION, No.3783, 2022