Study on Automatic Plan Method for Radiotherapy after Breast-conserving Surgery Based on TiGRT System / 中国医疗器械杂志

To study an automatic plan(AP) method for radiotherapy after breast-conserving surgery based on TiGRT system and and compare with manual plan (MP). The dosimetry parameters of 10 patients and the evaluation of scoring table were analyzed, it was found that the targets dose of AP were better than that of MP, but there was no statistical difference except for CI, The V5, V20 and V30 of affected lungs and whole lungs in AP were lower than all that in MP, the Dmean of hearts was slightly higher than that of MP, but the difference was not statistically significant, the MU of AP was increase by 16.1% compared with MP, the score of AP evaluation was increase by 6.1% compared with MP. So the AP could be programmed and automated while ensuring the quality of the plan, and can be used to design the plans for radiotherapy after breast-conserving surgery.

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.

Evaluation of plan quality between two treatment planning systems for volumetric modulated arc therapy / 中华放射肿瘤学杂志

Objective To investigate the plan quality between two treatment planning systems (TPSs) for volumetric modulated arc therapy (VMAT). Methods VMAT plans based on Varian Eclipse and Philips Pinnacle TPS were designed for 10 cervical cancer patients (2, 3 Arcs) and 10 prostate cancer patients ( 1, 2 Arcs) . The delivery system of VMAT was Varian ClinaciX machine, and RapidArc was used. The treatment plan quality between the two TPSs was evaluated based on dose distribution, delivery efficiency, and parameter settings. The differences between the two TPSs were compared using paired t-test. Results For cervical cancer patients, the 2-Arc VMAT plans based on the Pinnacle was slightly better than those based on the Eclipse in terms of the conformal index ( CI) of planning target volume ( PTV) , rectum V30 and V40 , and bladder V30 and V40 , and the homogeneity index ( HI) of PTV and PTV1 as well as CI of PTV1 in the Eclips were slightly better than those in the Pinnacle( P<005) Pinnacle were slightly worse than those in the Eclipse ( P>005) . The number of monitor units with 2-Arcs and 3-Arcs plans of the Eclipse was significantly smaller than those in the Pinnacle (P<005). For prostate cancer patients, The 1-arc VMAT plans of the Pinnacle TPS were slightly superior to those of the Eclipse TPS in terms of the HI of PTV, rectumV30 and V40 , and bladderV30 and V40 , but the former was slight inferior to the latter in terms of the CI of PTV (P<005). The number of monitor units of 1-arc and 2-Arcs plans showed no significant difference between the two TPSs (P>005). Conclusions For patients with cervical cancer and prostate cancer, the VMAT plans based on Varian Eclipse and Philips Pinnacle TPS can achieve a clinically acceptable dose distribution and show a little difference in the treatment plan quality. However, we will still need more cases to further study and determine the performance characteristics of the commercial TPSs for optimizing VMAT.

Evaluation of plan quality between two treatment planning systems for volumetric modulated arc therapy / 中华放射肿瘤学杂志

Objective To investigate the plan quality between two treatment planning systems (TPSs) for volumetric modulated arc therapy (VMAT). Methods VMAT plans based on Varian Eclipse and Philips Pinnacle TPS were designed for 10 cervical cancer patients (2, 3 Arcs) and 10 prostate cancer patients ( 1, 2 Arcs) . The delivery system of VMAT was Varian ClinaciX machine, and RapidArc was used. The treatment plan quality between the two TPSs was evaluated based on dose distribution, delivery efficiency, and parameter settings. The differences between the two TPSs were compared using paired t-test. Results For cervical cancer patients, the 2-Arc VMAT plans based on the Pinnacle was slightly better than those based on the Eclipse in terms of the conformal index ( CI) of planning target volume ( PTV) , rectum V30 and V40 , and bladder V30 and V40 , and the homogeneity index ( HI) of PTV and PTV1 as well as CI of PTV1 in the Eclips were slightly better than those in the Pinnacle( P<005) Pinnacle were slightly worse than those in the Eclipse ( P>005) . The number of monitor units with 2-Arcs and 3-Arcs plans of the Eclipse was significantly smaller than those in the Pinnacle (P<005). For prostate cancer patients, The 1-arc VMAT plans of the Pinnacle TPS were slightly superior to those of the Eclipse TPS in terms of the HI of PTV, rectumV30 and V40 , and bladderV30 and V40 , but the former was slight inferior to the latter in terms of the CI of PTV (P<005). The number of monitor units of 1-arc and 2-Arcs plans showed no significant difference between the two TPSs (P>005). Conclusions For patients with cervical cancer and prostate cancer, the VMAT plans based on Varian Eclipse and Philips Pinnacle TPS can achieve a clinically acceptable dose distribution and show a little difference in the treatment plan quality. However, we will still need more cases to further study and determine the performance characteristics of the commercial TPSs for optimizing VMAT.

Dosimetric comparison of helical tomotherapy and volume-modulated arc therapy for upper thoracic esophageal carcinoma / 中华放射医学与防护杂志

Objective To compare the dosimetric differences between helical tomotherapy (HT) and volume-modulated arc therapy (VMAT) in the treatment of upper thoracic esophageal carcinoma (UTEC).Methods A total of 10 patients with UTEC were randomly selected.HT plan and double-arc VMAT plan were designed and optimized for each patient.The prescription dose was 50 Gy/30 fractions for gross target volume (GTV), 66 Gy/30 fractions for planned target volume (PTV).The dose distribution and conformal index (CI), homogeneity index (HI) of target volume, the D1％, D5％, Dg5％, D99％, and dose of organ at risk (OAR) were analyzed by using the dose volume histogram (DVH).The monitor units and delivery time were also evaluated.Results For GTV and PTV, the D99％ of HT plans were slightly higher than those of VMAT plans (t =4.476, 3.756, P ＜ 0.05) , but no significant differences in D1％ , D5％ , D95％ , HI and CI (P ＞ 0.05) were found.The V10, V15, V20 and mean lung dose (MLD) to the total-lung of HT plans were all significantly lower than those of VMAT plans (t =-3.369,-4.824, -4.869,-3.657, P ＜ 0.05).There were no significant differences for V5, V30 and Dmax of cord (P ＞ 0.05).The monitor units and delivery time of VMAT plans were significantly lower than those of HT plans (t =13.970, 7.982, P ＜ 0.05).Conclusions Both HT and VMAT are appropriate for esophageal cancer radiotherapy.HT significantly reduces the radiation dose of the total-lung, while VMAT has obvious advantages in efficiency.

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.

Dosimetric evaluation of three techniques in postoperative radiotherapy for rectal cancer / 中华放射医学与防护杂志

Objective To evaluate the dosimetric characteristics of helical tomotherapy (HT),intensity-modulated radiation therapy (IMRT) and three-dimensional conformal radiation therapy (3D-CRT) for postoperative radiotherapy of rectal cancer.Methods Ten male patients with stage Ⅱ or Ⅲ middle or low position rectal cancer were selected retrospectively.All of the 10 patients underwent Dixon surgery and CT simulation orientation.The target volumes and normal organs were drawn in the CT images and the plans for HT,IMRT and 3D-CRT were designed.The prescribed dose was given 50 Gy in 25 fractions,covering at least 95％ of the planning target volume.Results All plans met the needs of the prescribed doses.The HT and IMRT plans met the needs of dose limit to organs at risk,however,the 3D-CRT plans failed to do that.The conformity indexes of HT,IMRT and 3D-CRT plans were 0.86,0.82 and 0.62,respectively (F =206.81,P ＜ 0.001),and the homogeneity indexes were 0.001,0.157,and 0.205,respectively (x2 =15.8,P ＜ 0.001).The 3D-CRT plans had larger volumes than the HT plans and IMRT plans in the high-dose regions such as pelvic V50,bladder V40,bowel V50 and femoral head D5 (P ＜ 0.05),but the differences between the HT plans and IMRT plans were not statistically significant (P ＞0.05).The V15 value of bowel of HT plans were higher than those of the IMRT and 3D-CRT plans (71.1％ vs.63.3％ and 67.7％,respectively).However,there was no significantly difference.Conclusions All of the HT,IMRT and 3D-CRT plans are able to meet the prescription dose requirement of the target regions of rectal cancer.The HT plans show the best dose homogeneity and target conformity,followed by the IMRT plans,and then the 3D-CRT plans.The HT plans meet the needs of all OARs slightly better than the IMRT plans.3D-CRT plans are simple and practical with poor protective ability toward the OARs.

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.

Radiation output evaluation of kilovoltage cone beam CT unit / 中国医疗器械杂志

<p><b>OBJECTIVE</b>To evaluate the radiation output and stability of linac-integrated kV cone beam CT unit.</p><p><b>METHODS</b>Air kermas in radiographic mode were measured with 0.6 cc ion chamber and Unidos electrometer for Synergy-integrated XVI kV cone beam CT unit. Air kermas vs image frames were measured in fluoroscopic mode. Output stability and depth doses were measured.</p><p><b>RESULTS</b>The air kerma increased quadratically with the increased tube voltage, while increasing linearly with the tube current, exposure time, and number of frames. The radiation output stability and its change with the gantry angle were within +/-1%. The percentage depth dose increased with higher tube voltage.</p><p><b>CONCLUSION</b>The radiation output of XVI is stable. The radiation outputs change considerably with the preset parameters. Parameters should be optimally chosen to reduce the patient dose.</p>

Effective dose evaluation for linac-integrated kV cone beam CT / 中华放射医学与防护杂志

Objective To evaluate the variations of effective doges with the preset scanning parameters from linac-integrated kV cone beam CT( CBCT). Methods Weighted CT dose index(CTDIW) were measured with PTW TM30009 CT ion chamber in head phantom and body phantom, respectively, for different combinations of tube voltage, mAs, collimator and gantry rotation range. Dose length products(DLP) were derived from CTDIW and effective doses(E) were calculated by the DLP and EDLP. Results CTDIW and effective dose had the quadratical relationship with tube voltage, depending linearly on product of tube current and exposure time. Effective dose had close relationship with the collimator and the gantry rotation range. Both the DLP and ED for CBCT were lower than the reference dose level recommended for conventional CT. Conclusions Effective dose from CBCT has a close relationship with the scanning parameters. Optimal imaging parameters should be chosen according to the patient's anatomy to reduce patient dose.

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.

Patient dose evaluation for kilovoltage cone beam CT in image-guided radiotherapy / 中华放射肿瘤学杂志

easurement should be performed in QA & QC program. Optimal image parameters should be chosen to reduce the scanning range and patient dose.

Treatment verification of helical tomotherapy intensity modulated radiation therapy / 中华放射肿瘤学杂志

Objective To evaluate the clinical feasibility of quality assurance of helical tomotherapy intensity modulated radiation therapy (IMRT) through a series of clinical case studies. Methods Tomotherapy planning system was used to provide optimized IMRT treatment plans. To verify the dose of IMRT plans,the cylindrical Virtual Water phantom,0.056cm3 AISL, ion chamber and EDR2 film were used for getting the absolute and relative doses from tomotherapy IMRT planning. The film and ion chamber were placed into the phantom. The doses of the interesting points and isodose distribution of the axial plane were measured,then the results were compared with those from the calculation in planning system for verification. Before the irradiation,kVCT images of the phantom were registered by tomotherapy MVCT images. So the setup of phantom was guided for verifying the position. Results The isedose distribution (on the axial plane) measured by the film was well consistent with that calculated by tomotherapy planning system. The error between the measured dose and predicted dose in the measured points was less than 3%. The setup error of the phantom was able to be kept within 1 mm. There was 2 mm offset along the vertical direction of couch from the virtual isocenter to beam isocenter,which should be considered during the phantom/patient setup. Conclusions The procedures for quality assurance of tomotherapy IMRT are feasible in our experience. And helical tomotherapy IMRT QA system has been constituted.