Relationship between gastric filling status and intra-or inter-fractional displacement of tumor in the preoperative radiotherapy of adenocarcinoma of the esophagogastric junction / 中华放射肿瘤学杂志

Objective:To investigate the relationship between gastric filling status and intra-or inter-fractional tumor displacement in patients with adenocarcinoma of the esophagogastric junction (AEG) undergoing preoperative radiotherapy.Methods:From October 2018 to June 2019, 10 patients with locally advanced AEG who received totally neoadjuvant therapy were enrolled in this prospective study. Patients received two markers implanted at the cranial and caudal borders of the tumors under gastroscope and a total of 20 fiducial markers were implanted finally. All patients underwent 4DCT scan under the gastric fasting and filling status. Ten images of 0% to 90% respiratory phase were automatically reconstructed by the system (Pinnacle 3, version 9.1, Philips Medical Systems, Eindhoven, The Netherland). Each patient obtained one hundred sets of images. Results:In the tumors proximal to the chest, gastric filling did not significantly affect intrafractional or interfractional tumor displacements. Nevertheless, in the tumors distal to the chest, the interfractional displacement in the cranio-caudal (CC) direction under the gastric fasting status was significantly larger compared with that under the gastric filling status (6.22±4.67 mm vs. 4.13±3.68 mm, P=0.013). To ensure 95% of the prescribed dose irradiated to at least 90% of the tumor volume during the radiotherapy, the margins of tumors proximal to the chest in the left-right (LR), antero-posterior (AP) and CC directions were 9 mm, 8.5 mm, 12.1 mm under gastric filling status with 300 ml semi-fluid. Six patients diagnosed with gastric cancer with proximal thoracic fiducial markers treated by preoperative radiotherapy were included in the validation group, revealing that the fiducial markers of 93% patients were covered in this margin. Conclusion:During the preoperative radiotherapy in AEG patient, the approach of quantitative gastric filling can be considered.

Clinical application and research progress on dose-guided radiotherapy / 中华放射肿瘤学杂志

Dose-guided radiotherapy (DGRT) is a potentially useful adaptive radiotherapy method which dosimetrically compensates for interfractional non-rigid deformation.With the improvement of in-room imaging quality,development of the deformation registration algorithm and innovation of computer science,the wide application of DGRT might be realized.The purpose of this article is to briefly summarize the work flow,clinical application and prospect of DGRT.

Clinical application and research progress on dose-guided radiotherapy / 中华放射肿瘤学杂志

Dose-guided radiotherapy (DGRT) is a potentially useful adaptive radiotherapy method which dosimetrically compensates for interfractional non-rigid deformation. With the improvement of in-room imaging quality, development of the deformation registration algorithm and innovation of computer science, the wide application of DGRT might be realized. The purpose of this article is to briefly summarize the work flow, clinical application and prospect of DGRT.

Interfractional dosimetric study of target volume and organs at risk following intracavitary brachytherapy for cervical cancer / 中华放射肿瘤学杂志

Objective To examine the interfractional dosimetric variations among inverse three-dimensional (3D) plan, forward 3D plan, and two-dimensional (2D) plan of intracavitary brachytherapy for cervical cancer, and to discuss the risk of implementing the interval plan on different implantation applicators at short time intervals.Methods Twenty-five groups of CT-guided intracavitary brachytherapy (two consecutive radiations at ≤4 d apart) plans from 11 cervical cancer patients who received radical radiation therapy in our hospital were reviewed and compared.The dwelling location and time of the first intracavitary brachytherapy plan (Plan-1) were simulated on the CT image of the second intracavitary brachytherapy to form Plan-1-S.The target coverage indices and D 2 cc of organs at risk (OARs) of Plan-1-S and Plan 2(actual plan of the second intracavitary brachytherapy) under the three planning modes were recorded and compared using the paired t-test, Wilcoxon signed rank test, and ANOVA.Results The D90, D100, and V100 of high-risk CTV were significantly lower in Plan-1-S created under the inverse mode in the actual plan (-9.11±13.46%,-13.16±18.79%, and-7.80±13.34%, P=0.002, 0.002, and 0.005, respectively).D90, D100, and V100 of the interval plan had the greatest reduction under the inverse mode (76%, 80%, and 76%, respectively).The maximum reductions in D90, D100, and V100 were 332.14 cGy (2D), 244.12 cGy (forward), and 41.76%(inverse).OAR overdose occurred most frequently under the forward mode;the rates of D90, D100, and V100 reductions accompanied by one OAR overdose were 29.41%, 37.50%, and 25.00%, and the rates of D90, D100, and V100 reductions by two OAR overdoses were 5.88%, 12.50%, and 6.25%,respectively.Overdose occurred most frequently in the small intestine (36%).Comparison of the three planning modes showed that the inverse plan had a greater reduction in each target coverage index than the 2D plan.Conclusions The simulated interval plan can significantly reduce target coverage and increase the risk of OAR overdose regardless of the planning mode and the short time intervals, and is therefore not recommended for clinical application.

The role of surgical clips in the evaluation of interfractional uncertainty for treatment of hepatobiliary and pancreatic cancer with postoperative radiotherapy

PURPOSE: To evaluate the utility of implanted surgical clips for detecting interfractional errors in the treatment of hepatobiliary and pancreatic cancer with postoperative radiotherapy (PORT). METHODS AND MATERIALS: Twenty patients had been treated with PORT for locally advanced hepatobiliary or pancreatic cancer, from November 2014 to April 2016. Patients underwent computed tomography simulation and were treated in expiratory breathing phase. During treatment, orthogonal kilovoltage (kV) imaging was taken twice a week, and isocenter shifts were made to match bony anatomy. The difference in position of clips between kV images and digitally reconstructed radiographs was determined. Clips were consist of 3 proximal clips (clip_p, ≤2 cm) and 3 distal clips (clip_d, >2 cm), which were classified according to distance from treatment center. The interfractional displacements of clips were measured in the superior-inferior (SI), anterior-posterior (AP), and right-left (RL) directions. RESULTS: The translocation of clip was well correlated with diaphragm movement in 90.4% (190/210) of all images. The clip position errors greater than 5 mm were observed in 26.0% in SI, 1.8% in AP, and 5.4% in RL directions, respectively. Moreover, the clip position errors greater than 10 mm were observed in 1.9% in SI, 0.2% in AP, and 0.2% in RL directions, despite respiratory control. CONCLUSION: Quantitative analysis of surgical clip displacement reflect respiratory motion, setup errors and postoperative change of intraabdominal organ position. Furthermore, position of clips is distinguished easily in verification images. The identification of the surgical clip position may lead to a significant improvement in the accuracy of upper abdominal radiation therapy.

Quantitative analysis for the interfractional volumetric changes of stereotactic ablative radiotherapy for early-stage or oligo-metastatic lung tumors / 中华放射医学与防护杂志

Objective To measure the volumetric changes precisely during stereotactic ablative radiotherapy for early-stage and oligo-metastatic lung tumors and optimize the treatment plan timely.Methods From October 2011 to October 2014, 66 patients with 71 early-stage or oligo-metastatic lung tumors received SABR.Median age was 66 years.To measure the volume of tumors, the verification images were registered before each treatment fraction with stimulation images by reference to bone structure.Tumors volume was measured by the first verification images, and were defined as the reference when evaluating the trend of tumors volume change during SABR treatment.Generalized estimated equations were used to analyze the trend of the change of tumors volume over time with several possible predictors.The primary plan (P-plan) was modified when the biological effective dose (BED) of a tumor reached 60 Gy and volume change reached 25％.The modified plan was named as M-plan.Paired t-test was used to compare the dose of organs at risk (OAR) between M-plan and P-plan.Results In 71 tumors, 49 (69％) tumors showed volumetric shrinkage, 21 (30％) tumors showed enlargement and 1 tumor showed invariance.Generalized estimated equation showed no statistical significance (P =0.281) for the volumetric shrinkage of lung tumors.M-plan was made in 26 tumors.Of these tumors, 21 tumors decreased over 25 ％ and the result of paired t-test showed V5 of lung, Dmax and D1.2 cm3 of spinal cord, Dmax and D5 cm3 of esophagus and D30 cm3 of chest wall were statistically different between two plans(t =3.139 ～11.939 ,P＜0.05).5 tumors enlarged over 25％ and the result of paired t-test showed V5 and V20 of lung,Dmax and D1.2cm3 of spinal cord, Dmax of esophagus and D30cm3 of chest wall were statistically different between the two plans(t =-10.436--2.518, P ＜ 0.05).Conclusions Size of lung tumors changed dynamically during SABR, but it is unnecessary to modify treatment plans for all tumors.The tumors which showed obvious volumetric change may benefit from modifying treatment plans.

Variation of organ position and dose for cervical cancer patients treated with helical tomotherapy / 中华放射医学与防护杂志

Objective To observe the interfractional variation and actual dose for cervical cancer patients treated with tomotherapy.Methods Five patients who received tomotherapy were chosen from Aug 2013 to Feb 2014.A megavohage computed tomography (MVCT) scan was performed before treatment and then registered with the planning CT images.Dose distributions were recalculated and targets were contoured on the MVCT images.The differences between the actual radiation and planning were analyzed.Results In the patients received external radiotherapy, the decline in cervix volume and maximum diameter was 68.90％ and 26.91％ , respectively (t =5.21, 8.39, P ＜0.05).Cervix, uterus and CTV movement in left-right, anteroposterior, superoinferior were 1.43,-7.72, 0.02,-0.40,-1.24, -6.51,-0.43,-1.68and-0.22mm.The medianCTV V95％ was 99.40％ (95.96％-100％), and missing volume was 6.94 cm3 (0-32.30 cm3).Conclusions During radiotherapy for cervical cancer patients, the volume, position and doses are different between initial plan and actual radiation.Based on image guided radiation therapy (IGRT), missing targets are limited.

Study of inter-fractional variations and adaptive radiotherapy in pancreatic cancer / 中华放射肿瘤学杂志

ObjectiveTo quantitatively characterize the inter-fractional anatomy variations and advantages of dosimetry for the adaptive radiotherapy in pancreatic cancer.MethodsA total of 226 daily CT images acquired from 10 patients with pancreatic cancer treated with image-guided radiotherapy were analyzed retrospectively.Targets and organs at risk (OARs) were delineated by the atlas-based automatic segmentation and modified by the skilled physician.Various parameters,including the center of mass (COM) distance,the maximal overlap ratio (MOR) and the Dice coefficient (DC),were used to quantify the inter-fractional organ displacement and deformation.The adaptive radiation therapy (ART) was applied to handle the daily GT images.The dose distributions parameters from the ART plan were compared with those from the repositioning plan.ResultsThe inter-fractional anatomy variations of pancreas head were obvious in the pancreatic cancer irradiation.The mean COM distance,MOR and DC of pancreas head after the bony or soft tissue alignment and registration was ( 7.8 ± 1.3 ) mm,( 87.2 ± 8.4 )％ and ( 77.2 ±7.9)％ respectively.Compared with the repositioning plan,the ART plan had better target coverage and OARs sparing.For example,the mean V100 of PTV was improved from (93.32 ± 2.89) ％ for repositioning plan to ( 96.03 ± 1.42) ％ for ART plan with t =2.79,P =0.008 and the mean V50.4 for duodenum was reduced from (43.4 ± 12.71 )％ for the repositioning plan to (15.6 ± 6.25)％ for the ART plan with t =3.52,P=0.000.ConclusionsThe ART can effectively account for the obvious inter-fractional anatomy variations in pancreatic cancer irradiation and be used to escalate the radiotherapy dose for the pancreatic cancer,which will lead to a promising higher local control rate.

A Bile Duct Cancer Patient Whose Stent Shifted Significantly Over the Course of External Beam Radiotherapy / 대한방사선종양학회지

The author reports a bile duct cancer patient whose stent shifted significantly from right to left over the course of radiotherapy. The 80-year-old female patient had a short stature with thoracic kyphosis and mutiple spinal compression fractures. She was also emaciated and very lean. By comparing the weekly scanned computed tomography images, the author found her stent to have shifted by more than 4 cm from right to left over the course of external beam radiotherapy. The results of this case study suggest that for a very lean and emaciated kyphotic bile duct cancer patient, the possibility of large interfractional movement of the bile duct or stent during radiotherapy should be considered.

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.

Set-up errors in radiation therapy for pelvic tumor patients of different somatotypes / 医学研究生学报

Objective: The purpose of this study was to quantitatively assess the systematic and random errors in radiation therapy for pelvic tumor patients of different somatotypes and seek an individualized mathematic basis for defining the planning target volume(PTV) and planning organ at risk volume(PRV) in 3 dimensional space.Methods: Thirty patients with pelvic tumor were immobilized by thermoplastic body mask in a spine position and divided into four somatotypes according to their body mass indexes(BMI).CT simulations were performed and digitally reconstructed radiographs(DRR) were generated as the reference image.To define the appropriate PTV-and PRV-margins for intensity modulation radiated therapy(IMRT),inter-fractional set-up errors and intra-fractional organ motions were quantitatively evaluated in the right-left(R-L),anterior-posterior(A-P) and cranial-caudal(C-C) directions.And the frequency of shift in the three directions were observed.Results: For the pelvic tumor patients with different BMIs,the inter-fractional set-up errors of the emaciated,moderate,overweight and obese somatotypes were 1.8,1.8,2.2 and 2.7 mm in the R-L direction,2.2,1.8,3.6 and 2.8 mm in the A-P direction,and 2.4,2.1,2.7 and 2.6 mm in the C-C direction.The intra-fractional organ motions of the four somatotypes were 1.9,1.9,2.3 and 2.5 mm in the R-L,2.1,2.2,2.9 and 3.0 mm in the A-P,and 1.8,1.9,2.2 and 2.5 mm in the C-C direction.Conclusion: In the pelvic irradiation,the definition of PTV and PRV should be individualized.