Automatic Post-operative Cervical Cancer Target Area and Organ at Risk Outlining Based on Fusion Convolutional Neural Network / 中国医疗器械杂志

CT image based organ segmentation is essential for radiotherapy treatment planning, and it is laborious and time consuming to outline the endangered organs and target areas before making radiation treatment plans. This study proposes a fully automated segmentation method based on fusion convolutional neural network to improve the efficiency of physicians in outlining the endangered organs and target areas. The CT images of 170 postoperative cervical cancer stage IB and IIA patients were selected for network training and automatic outlining of bladder, rectum, femoral head and CTV, and the neural network was used to localize easily distinguishable vessels around the target area to achieve more accurate outlining of CTV.

A fusion network model based on limited training samples for the automatic segmentation of pelvic endangered organs / 生物医学工程学杂志

When applying deep learning to the automatic segmentation of organs at risk in medical images, we combine two network models of Dense Net and V-Net to develop a Dense V-network for automatic segmentation of three-dimensional computed tomography (CT) images, in order to solve the problems of degradation and gradient disappearance of three-dimensional convolutional neural networks optimization as training samples are insufficient. This algorithm is applied to the delineation of pelvic endangered organs and we take three representative evaluation parameters to quantitatively evaluate the segmentation effect. The clinical result showed that the Dice similarity coefficient values of the bladder, small intestine, rectum, femoral head and spinal cord were all above 0.87 (average was 0.9); Jaccard distance of these were within 2.3 (average was 0.18). Except for the small intestine, the Hausdorff distance of other organs were less than 0.9 cm (average was 0.62 cm). The Dense V-Network has been proven to achieve the accurate segmentation of pelvic endangered organs.

Research on automatic segmentation of female bowel based on Dense V-Network neural network / 中华放射肿瘤学杂志

Objective:To resolve the issue of poor automatic segmentation of the bowel in women with pelvic tumors, a Dense V-Network model was established, trained and evaluated to accurately and automatically delineate the bowel of female patients with pelvic tumors.Methods:Dense Net and V-Net network models were combined to develop a Dense V-Network algorithm for automatic segmentation of 3D CT images. CT data were collected from 160 patients with cervical cancer, 130 of which were randomly selected as the training set to adjust the model parameters, and the remaining 30 were used as test set to evaluate the effect of automatic segmentation.Results:Eight parameters including Dice similarity coefficient (DSC) were utilized to quantitatively evaluate the segmentation effect. The DSC value, JD, ΔV, SI, IncI, HD (cm), MDA (mm), and DC (mm) of the small intestine were 0.86±0.03, 0.25±0.04, 0.10±0.07, 0.88±0.05, 0.85±0.05, 2.98±0.61, 2.40±0.45 and 4.13±1.74, which were better than those of any other single algorithm.Conclusion:Dense V-Network algorithm proposed in this paper can deliver accurate segmentation of the bowel organs. It can be applied in clinical practice after slight revision by physicians.

Automated Pre-delineation of CTV in Patients with Cervical Cancer Using Dense V-Net / 中国医疗器械杂志

We use a dense and fully connected convolutional network with good feature learning in small samples, to automatically pre-deline CTV of cervical cancer patients based on CT images and evaluate the effect. The CT data of stage IB and IIA postoperative cervical cancer with similar delineation scope were selected to be used to evaluate the pre-sketching accuracy from three aspects:sketching similarity, sketching offset and sketching volume difference. It has been proved that the 8 most representative parameters are superior to those with single network and reported internationally before. Dense V-Net can accurately predict CTV pre-delineation of cervical cancer patients, which can be used clinically after simple modification by doctors.

Evaluation of the auto-segmentation based on self-registration and Atlas in adaptive radiotherapy for cervical cancer / 中华放射肿瘤学杂志

Objective To evaluate the accuracy and validate the feasibility of auto-segmentation based on self-registration and Atlas in adaptive radiotherapy for cervical cancer using MIM-Maestro software.Methods The CT scan images and delineation results of 60 cervical cancer patients were obtained to establish the Atlas template database.The planning CT (pCT) and replanning CT (rCT) images were randomly selected from 15 patients for the contouring of clinical target volume (CTV) and organs at risk (OAR) by an experienced radiation oncologist.The rCT images of 15 patients were auto-contoured using Atlas-based auto-segmentation (Atlas group),and mapping contours from the pCT to the rCT images was performed by rigid and deformable image registration (rigid group and deformable group).The time for the three methods of auto-segmentation was also recorded.The similarity of the auto-contours and reference contours was assessed using dice similarity coefficient (DSC),overlap index (OI),the average hausdorff distance (AHD) and the deviation of centroid (DC),and the results were statistically compared among three groups by using one-way analysis of variance.Results The mean time was 89.2 s,22.4 s and 42.6 s in the Atlas,rigid and deformable groups respectively.The DSC,OI and AHD for the CTV and rectum in the rigid and deformable groups significantly differed from those in the Atlas group (all P＜0.001).In the rigid and deformable groups,the OI for the intestine significantly differed from that in the Atlas group.The mean DSC for CTV was 0.89 in the rigid and deformable groups,and 0.76 in the Atlas group.The optimal delineation of the bladder,pelvis and femoral heads was obtained in the deformable group.Conclusions AIl three methods of auto-segmentation can automatically and rapidly contour the CTV and OARs.The performance in the deformable group is better than that in the rigid and Atlas groups.

Evaluation of the quality and efficiency of SRT plans for intracranial tumors using Fixed and Iris collimators of CyberKnife / 中华放射肿瘤学杂志

Objective To discuss and evaluate the dosimetric characteristics of different plans implementing stereotactic radiotherapy(SRT)for intracranial tumors using Fixed and Iris collimators of CyberKnife VSI.Methods Twenty patients with intracranial tumors were selected and divided into group A with a small target volume(≤30 cm3)and group B with a large target volume(≥30 cm3). There were 10 patients in each group,and the prescribed dose to the target was 21 Gy in 3 fractions. For each patient, two treatment plans were designed using Fixed and Iris collimators. By analyzing the dosimetric parameters such as conformity index(CI),homogeneity index(HI), gradient index(GI), gradient score index(GSI), and organs at risk (OAR),the quality and efficiency of the plans were evaluated in order to discuss the beam characteristics for two sets of collimators. The difference was analyzed with the paired t-test. Results The mean time of Iris plan for delivering was significantly less than that of Fixed plan(group A:P=0.001;group B:P=0.000). In group B,the peripheral dose(20% and 10% of the prescribed dose)volumes of Fixed plan were significantly less than those of Iris plan(P=0.001 and 0.009). For OAR,D minof the visual pathway and D meanor D minof the eyeball in group B were significantly different between Fixed and Iris plans(all P<0.05), while in group A, only D minof the optic chiasm was significantly different between the two plans(P=0.043). For the other parameters of targets,there were no significant differences between Fixed and Iris plans in both groups(all P>0.05). Conclusions Apart from less treatment time in the Iris plan, there are no significant dosimetric differences between the two collimator plans of CyberKnife VSI in treating small intracranial tumor. For the large and complex tumor,although Iris plan meets the requirement for OAR dose constraints,its low-dose volumes are larger than those of Fixed plan. Further studies of the dosimetric characteristics in CyberKnife should be done.

Real-time patient transit dose verification of volumetric modulated arc therapy by a 2D ionization chamber array / 中华放射肿瘤学杂志

Objective To study the real?time dose verification with 2D array ion chamber array in volumetric modulated arc therapy ( VMAT) with a 2D array ion chamber array. Methods The 2D ion chamber array was fixed on the panel of electronic portal imaging device (EPID). Source?detector distance (SDD) was 140 cm. 8 mm RW3 solid water was added to the 2D array to improve the signal noise ratio. Patient plans for esophageal, prostate and liver cancers were selected to be delivered on the cylindrical Cheese phantom 5 times in order to validate the reproducibility of doses. Real?time patient transit dose measurements were performed at each fraction. Dose distributions were evaluated using gamma index criteria of 3 mm DTA and 3% dose difference referred to the first time result. Results The gamma index pass rate in the Cheese phantom were about 98%;the gamma index pass rate for esophageal, prostate and liver cancer patient were about 92%, 92% and 94%, respectively. Gamma pass rate for all single fraction were more than 90%. Conclusions The 2D array is capable of monitoring the real time transit doses during VMAT delivery. It is helpful to improve the treatment accuracy.

Patient-specific dose verification method using ArcCHECK for total marrow irradiation with intensity modulated arc therapy / 中国医疗器械杂志

To investigate the patient-specific dose verification method using ArcCHECK for total marrow irradiation (TMI) with Volumetric Modulated Arc Therapy (VMAT) and Helical Tomotherapy (HT). The kVCT images collected from 8 patients were respectively designed for RapidArc and Tomotherapy plans in total marrow irradiation. ArcCHECK was used for dose verification for the head-neck, chest-abdomen and pelvic. The merging function of ArcCHECK was used in VMAT and the method of double plans (reference and delivery plans) were used in HT. The γ-analysis passing rates for the head-neck, chest-abdomen, pelvic were 98.9% ± 1.9%, 98.4% ± 1.8%, 97.4% ± 2.1% for VMAT plans and 94.3% ± 1.5%, 96.5 ± 1.2%, 94.1% ± 1.9% for HT plans. The results show that using the merging function of ArcCHECK can achieve the dose verification well for VMAT plans with TMI. The method of double plans was done for the dose verification of HT plans with TMI as well as the plans with the targets keeping away from the set-up center.

The Dose Effect of Isocenter Selection during IMRT Dose Verification with the 2D Chamber Array / 中国医疗器械杂志

To investigate the dose effect of isocenter difference during IMRT dose verification with the 2D chamber array. The samples collected from 10 patients were respectively designed for IMRT plans, the isocenter of which was independently defined as P(o), P(x) and P(y). P(o) was fixed on the target center and the other points shifted 8cm from the target center in the orientation of x/y. The PTW729 was used for 2D dose verification in the 3 groups which beams of plans were set to 0 degrees. The γ-analysis passing rates for the whole plan and each beam were gotten using the different standards in the 3 groups, The results showed the mean passing rate of γ-analysis was highest in the P(o) group, and the mean passing rate of the whole plan was better than that of each beam. In addition, it became worse with the increase of dose leakage between the leaves in P(y) group. Therefore, the determination of isocenter has a visible effect for IMRT dose verification of the 2D chamber array, The isocenter of the planning design should be close to the geometric center of target.

Effect of hypofractionated intensity-modulated radiation therapy on acute toxicities for locally advanced squamous cell carcinoma of the hypopharynx / 中国肿瘤临床

Objective: To evaluate the feasibility of hypofractionated intensity-modulated radiation therapy (IMRT) combined with concurrent chemotherapy in patients with locally advanced squamous cell carcinoma of the hypopharynx. Methods:Patients with stageⅢ-ⅣA carcinoma of the hypopharynx were treated with IMRT and cisplatin-based concurrent chemotherapy. Two groups were di-vided according to the prescription dose to the primary gross tumor volume, as follows:Cohort-1 comprised patients who were recruit-ed before February 2013 (70 Gy/33 F and 2.12 Gy/F);and Cohort-2 comprised patients who were recruited since February 2013 (69 Gy/30 F and 2.30 Gy/F). Acute toxicities were evaluated. This study was registered with the number ChiCTR-ONRC-14004240. Results:Between August 2008 and December 2014, a total of 76 patients (35 in Cohort-1 and 41 in Cohort-2) were recruited. No xerostomia of grade 3 and higher was observed in all patients, who showed low incidences of grade 3 skin reaction, oral mucositis, and dysphagia. All patients did not show acute toxicities of higher than grade 4. No statistical differences in acute toxicities were observed between the two cohorts. No statistical difference was observed in acute toxicities between the IMRT techniques. Induction chemotherapy was the inde-pendent prognostic factor for grade 2 xerostomia (P=0.002). Conclusion:The 69 Gy/30 F hypofractionated IMRT was safe and effec-tive in the treatment of locally advanced squamous cell carcinoma of the hypopharynx. Late toxicities and long-term outcome need to be investigated further.

A comparison between two-dimensional ion chamber array and EDR2 film for intensity modulated planning of helical tomotherapy / 中华放射肿瘤学杂志

Objective The aim of this work is to compare the performances of EDR2 film dosimetry with two-dimensional ion chamber array (2DICA) in quality assurance (QA) procedures and to investigate the origin of possible discrepancies between the two methods.Methods A 2DICA, I′mRT MatriXX and MULTICube equivalent solid water phantom from IBA Company were used to verify the dose distribution of 15 tomotherapy plan cases.The combined phantom which includes EDR2 film on the array was set up to measure the dose distribution from coronal and sagittal orientations.After the irradiation, the dose distributions of 2DICA and film were compared with those calculated in the planning system for verification.The results and efficiency were evaluated independently in the two methods.Results The mean number of points satifying γ parameter ≤1 in the coronal and sagittal planes was 97.00%±1.56%& 95.98%±2.52%(t=-2.22,P=0.043) and 98.28%±1.55%& 95.42%±1.99%(t=0.75,P=0.464) of the 15 cases respectively for 2DICA and EDR2 film.The ratio of more than 90% and 95% were 93.3% and 66.7%.The results we presented show a very good agreement between the two methods when used to assess the dose distribution between calculated and measured doses,and a certain degree of correlation (r=0.14,P=0.001).Conclusions The 2DICA may effectively replace both film and ion chamber dosimetry in routine IMRT QA.The good agreement between 2DICA and EDR2 film may give a possible check regularly just as a gold standard.

Primary application of active breathing control system in conformal radiotherapy for patients with non-small cell lung cancer / 中华放射肿瘤学杂志

Objective To evaluate the feasibility of active breathing control (ABC) in conformal radiotherapy (CRT) for patients with non-small cell lung cancer (NSCLC). Methods From Feb 2005 to Mar 2008, 29 patients with inoperable NSCLC (stage Ⅱ-Ⅳ) were evaluated. For each patient, two series of CT scans were obtained with free breathing (FB) and ABC system during simulation, respectively. Then two confonnal radiotherapy (CRT) plans were finished based on the two sets of reconstructed images. The pattern of post-inspiratory breath-hold was triggered at 80% of the peak of inspiration curve. The margin of clinical target volume (CTV) to planning target volume (PTV) was 0. 6 cm for lesions of the superior lobe, and 1.0 cm for the lesions of middle and inferior lobes. Three to five coplanar fields were performed in conformal radiotherapy. The gross tumor volume (GTV), CTV, PTV, volume of the bilateral lungs (Volume_(lung)), V_(20) and mean lung dose (MLD) of two plans were evaluated by dose-volume histogram (DVH). The World Health Organization criteria and National Cancer Institute Common Toxicity Criteria 3.0 (NCI-CTC3.0) scale were used to assess the immediate response and acute side-effect, respectively. Results Significant differences of GTV, CTV, FIN, Volum_(lung), V_(20) and MDL were observed between the two plans (36. 35 cm~3 vs. 31.40 cm~3, t = 9. 70, P <0. 001 ;82. 33 cm~3 vs. 70. 83 cm~3, t = 8. 19, P < 0. 001 ; 230. 73 cm~3 vs. 197.59 cm~3 ,t=5.72,P <0. 001 ;21.66% vs. 18. 76% ,t = 11.16,P <0. 001 ;1329. 07 Gy vs. 1143. 14 Gy, t = 13. 24, P < 0. 001). With ABC, all patients completed their treatment successfully except one patient for financial problems. The median radiation dose to the GTV was 64 Gy (60 -64 Gy). The overall immediate response rate was 64% (18/28). According to the NCI-CTC 3.0, grade 1 and 2 acute radiation-related toxicities occurred in 68% (19/28) and 18% (5/28) of patients for esophagitis, 82% (23/28) and 7% (2/28) for pneumonitis, respectively. Grade 1, 2 and 3 bone marrow suppression occurred in 57% (16/28), 25% (7/28) and 14% (4/28) of patients, respectively. Grade 1 and 2 acute cardiac injuries occurred in 86% (24/28) and 14% (4/28) of patients. Conclusions During CRT for patients with NSCLC, the use of ABC can decrease the radiation dose and acute complications of normal tissues.

Dosimetric study of three different kinds of radiotherapy technique for post-operative breast cancer / 中华放射医学与防护杂志

Objective To investigate the dosimetric characteristics of helical tomotherapy(HT),intensity-modulated radiation therapy(IMRT)and three.dimensional conformal radiation therapy(3D-CRT)for the post-operative breast cancer as well as their comparison in protecting the normal tissues.Methods The CT images of 10 postoperative patients with early stage breast cancer were transferRed into HT and IMRT and 3D- CRT planning system respectively after the target region and normal tissues were drawn out with the same doctor.Each prescribed dose for three kinds of plans was 50 Gy/25 fractions.Inrradiation doses and volume at heart and double lungs as well as conformity index(CI)and homogeneity index(HI)were evaluated.Results The PTV volume of prescribed target dose of 95% and 100%in HT, IMRT and 3D-CRT groups were 99.13%and 95.87%,97.80%and 94.05%,96.37%and 87.29%.respectively.The CI and HI in HT.IMRT and 3D-CRT groups were 0.80±0.10 and 1.09 ±0.03,0.65±0.07 and 1.14±0.02,0.40±0.08 and 1.17±0.04,respectively V5,V10 and V20 of the heart were the lowest at 3D-CRT than HT and lM RT.V5 of the diseased lung was the lowest at 3D-CRT compared to HT and IMRT.V5 and V10 of the healthy lung were the lowest at 3 D-CRT compared to other groups.Conclusions Compared with IMRT and 3D-CRT.HT technique in treating breast cancer had the best conformity index and homogeneity index as well as steeper dose gradient.Irradiated doses and volume at the heart was the lowest at 3D- CRT and the highest at IMRT.Irradiated doses and volume of the heart and healthy lung as well as the diseased lung were the lowest at 3D-CRT compared to HT and IMRT groups.

Dosimetric comparison between helical tomotherapy and step-and-shoot intensity modulated radiation therapy for cervix carcinoma / 中华放射医学与防护杂志

Objective To compare the dosimetric characteristics of helical tomotherapy(HT)and step-and-shoot intensity modulated radiotherapy(IMRT)for post-operative cervix cancer patients. Methods Ten patients with post-operative cervix cancer were enrolled in this study.HT and IMRT plans were developed for each patient.The dose distributions of the targets,organs at risk(OARs),CI and HI were analyzed and compared.The prescribed dose was 60 Gy/25 f for CTV1,50 Gy/25 f for CTV2.The iso-dose line of 50 Gy was used.Results The homogeneity indexes(HI)(0.94±0.03),conformity index(C1)(1.28±0.02)in HT group were better than in IMRT group(0.85±0.01 and 1.36±0.03),respectively(t=5.12,-6.34,P<0.001).The Dmean of PTV in HT group(51.77 Gy)was lower than that in IMRT group(54.53 Gy)(t=-8.01,P<0.05).The Dmax ,Dmean,V30,V40 and V50 of bladder、rectum and small bowel were lower in HT group than those in IM RT group.The Dmax,Dmean,V30 and V40 of right and left femoral head were lower in HT group than those in IMRT group.Conclusion Helical tomotherapy treatment plan has a better homogeneity,steeper dose gradient,and a better protection for organs at risk.

Analysis of megavoltage computed tomography imaging on a helical tomotherapy unit / 中国医疗器械杂志

<p><b>OBJECTIVE</b>To evaluate the image quality of megavoltage computed Tomography imaging.</p><p><b>METHODS</b>The HU uniformity and linearity, image noise, spatial resolution, low contrast resolution and spatial linearity in MVCT mode were evaluated with Catphan 600 phantom, and the factor of pitch was also evaluated. Influencing factors of image quality were also discussed.</p><p><b>RESULTS</b>The MVCT values depended linearly on the physical density of the sample. The MVCT values uniformity was good. The spatial resolution was 4 lp/cm. The use of an MV Beam for imaging results in the loss of low contrast resolution, but it is sufficient for pretreatment image guidance. The geometric accuracy was good.</p><p><b>CONCLUSIONS</b>The image quality of MVCT is less than that of KVCT, but is good enough for IGRT.</p>

Dose Analysis of a Diode Array for Dose Verification of Rotational Intensity Modulated Radiation Therapy Planning / 中国医学物理学杂志

Objective: Quality assurance (QA) of intensity modulated radiotherapy (IMRT) dosimetry is a laborious task. The goal of this work is to evaluate the dosimetric characteristics of a new 2D diode array and assess the role it can play in routine MRT QA. Methods: A diode array, MapCHECK~(TM) and MapPHAN phantom from Sun Nuclear corporation (USC) were used for verifying the dose distribution of 10 tomotherapy IMRT plan cases. The combined phantom was set up to measure the dose distribution from coronal and sagittal orientations. After MVCT registration, the measured dose distributions of the coronal and sagittal planes were compared with those from calculation in the planning system. The results were evaluated by the absolute doses. The feasibility of the different measuring methods were studied. Results: The dose distribution measured by the MapCHECK~(TM) 2D array was well consistent with that calculated by tomotherapy planning system. In the comparison of the MapCHECK~(TM) measured versus planning system calculated using the 3mm/3% and 4mm/4% γ criteria, the number of detectors with γ parameter ≤ 1 was 96.8%/99.38% and 96.99%/99.49% average of the 10 cases respectively, for coronal and sagittal orientations. The acceptance criteria which is the combined 3mm/3% analysis would be introduced. And the number of points required to pass was generally 90%. Conclusions: MapCHECK~(TM) with MapPHAN phantom has been successfully tested for HT dose verification, and offers users an accurate and convenient rotational dosimetry solution.

Two-dimensional ion chamber array in dose verification for intensity modulated planning of helical tomotherapy / 中华放射肿瘤学杂志

Objective To investigate the feasibility of dose verification of intensity modulated (IM) planning of helical tomotherapy (HT) using two-dimensional ion chamber array (2DICA),and develop an efficient way to validate the dose delivered under the parameters mirroring those during the treatment. Meth-ods A 2DICA,I'mRT MatriXX and MULTICube equivalent solid water phantom from IBA company were used to verify the dose distribution of 10 IM planning. The combined phantom was set up to measure the dose distributions on coronal and sagittal surface. The precise setup of phantom was guided by HTMVCT images. After the irradiation, the measured dose distributions on the coronal and sngittal plane were compared with those calculated by the IM planning system for verification. The results were evaluated and the feasibility of the different measuring methods was studied. Results The dose distribution measured by the MatriXX 2DICA was well consistent with that calculated by the treatment planning system. The errors between the measured dose and predicted dose in the selected points were within ±3%. In the comparison of the pixel-segmented ionization chamber versus treatment planning system using the 3 mm/3% γ criteria, the passing ratio of pixels with γ parameter ≤1 was 97.76% and 96.83%, respectively. Conclusions MatriXX is a-ble to measure the absolute and relative dose distributions simultaneously,which can be used for dose verifi-cation of IM planning.