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Objective:To explore the clinical value of 18F-fluoromisonidazole (FMISO) PET/CT hypoxia imaging in early response to heavy ion radiotherapy in patients with non-small cell lung cancer(NSCLC). Methods:From April 2018 to January 2021, the 18F-FMISO PET/CT images of 23 NSCLC patients (19 males, 4 females; age (64.9±10.3) years) who received heavy ion radiotherapy in Shanghai Proton and Heavy Ion Center were retrospectively analyzed. The evaluation parameters included tumor volume (TV), tumor to background ratio (TBR) before and after radiotherapy. Patients were divided into hypoxia group and non-hypoxia group with the baseline TBR value≥1.4 as hypoxia threshold. Wilcoxon signed rank test was used to compare the differences of TV and TBR before and after radiotherapy in 2 groups. Results:Of 23 NSCLC patients, 17 were hypoxia and 6 were non-hypoxia. Compared with the baseline, TV after the radiotherapy (59.44(22.86, 99.43) and 33.78(8.68, 54.44) cm 3; z=-3.05, P=0.002) and TBR after the radiotherapy (2.25(2.09, 2.82) and 1.42(1.24, 1.67); z=-3.39, P=0.001) of the hypoxia group were significantly lower, while TV (16.19(6.74, 36.52) and 8.59(4.38, 25.47) cm 3; z=-1.57, P=0.120) and TBR (1.19(1.05, 1.27) and 1.10 (0.97, 1.14); z=-1.89, P=0.060) of the non-hypoxia group decreased with no significant differences. Conclusions:Hypoxic NSCLC tumors are sensitive to heavy ion radiation. Compared with non-hypoxic tumors, hypoxic tumors respond more quickly, and a significant reduction in TV can be observed early after radiotherapy. Heavy ion radiation can significantly improve tumor hypoxia.
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Objective:Patients are breathing freely during adjuvant proton pencil beam radiotherapy after breast conserving surgery. Fluctuation of the thorax may affect the position of the end of the proton beam flow, which needs to be precisely evaluated on a millimeter scale.Methods:For 20 patients with breast cancer treated with proton radiotherapy after breast conserving surgery, PET-CT scan was performed approximately 10 min after the end of proton radiotherapy. The images of PET-CT were processed for ROI determination and sampling line (profile) extraction on a Raystation RV workstation to calculate the actual difference between the predicted and real radioactivity from the same spatial location as obtained by PET acquisition R50. Then, the differences in the spatial location between the actual process of proton irradiation and the planned process were obtained. Depth difference values for each pair of sampling lines were presented. Results:For 20 patients with breast cancer with a median follow-up of 22 months (range 12 - 46 months), all patients survived at the last follow-up, and no radiation pneumonitis was observed during the follow-up period. Among the verification results of 21 cases, the depth difference of evenly distributed was (-0.75±1.89) mm in the primary field and (-0.82±2.06) mm in the secondary field; The depth difference of sequential treatment was (1.81±1.87) mm in the primary field and (1.32±1.74) mm in the secondary field; The depth difference of synchronous addition in the primary field was (-1.47±1.44) mm, and the depth difference in the secondary field was (-1.48±2.11) mm.Conclusion:The results of off-line PET-CT in vivo biological verification show that the accuracy of the dose boundary cut-off was within 3 mm in breast cancer patients, which meets the clinical and physician requirement for the precision in breast cancer treatment.
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Objective:To test the usefulness of PET-range verification (RV) method for proton radiation accuracy verification in poly (methyl methacrylate) (PMMA) phantom using off-line PET/CT scanning.Methods:Proton irradiation dose of 2 Gy and 4 Gy were delivered in PMMA phantom. Given the difference of clinical target volume (CTV), 7 subgroups with different depth (5.0, 7.5, 10.0, 12.5, 15.0, 17.5, 20.0 cm) were set for each dose (14 radiation plans or radiation fields). PET/CT scan was performed 10 min after irradiation of 48-221 MeV proton beam. A co-registration between CT from treatment planning system and PET/CT was performed, as well as the smoothing and normalization of PET/CT data. The region of interest (ROI) and profile lines were drawn with the Raystation PET-RV software. The predictive induced radioactivity and the measured induced radioactivity profile lines were analyzed to evaluate the Δ R50, namely, the error at the position corresponding to 50% of the maximum predictive induced radioactivity at the end of both curves. Results:The size of each ROI was 5.0 cm×5.0 cm×2.5 cm. Profile lines were evenly distributed with the interval of 3 mm, and totally 289 pairs of profile lines were drew. The 2 Gy- and 4 Gy-dose groups yielded similar mean depth errors (Δ R50 between 1 mm and -1 mm with a standard deviation <1 mm). Conclusions:The off-line PET/CT scanning of PMMA phantom reveals a good agreement between predicted and measured PET data, with error of ±1 mm. The PET-RV method can be extended to clinical cases′ verification in human body treatment with further investigation.
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Objective:To compare dose distributions between photon versus proton and carbon ion radiotherapy (particle therapy, PT) among patients with gross tumors, and to evaluate the safety and efficacy of PT for thymic malignancies (TM).Methods:From Sept 2015 to Aug 2018, 19 patients with TM who underwent non-palliative PT using pencil beam scanning technique in our hospital and had at least one follow-up were retrospectively analyzed. Diseases staged from Ⅰ-Ⅳ B including 15 Ⅲ-Ⅳ B. All the patients had pathological diagnosis with 10 thymomas, 6 carcinomas and 3 neuroendocrine tumors of the thymus. A set of dosimetric comparisons were conducted in patients with gross tumors at a total dose of 66 GyE, in 33 fractions for photon or proton beams and in 22 fractions for carbon ion beams. Five patients without any local treatment and 7 patients after R2 resection received radical radiotherapy of proton 44.0-48.4 GyE in 20-22 fractions plus carbon ion 21.0-23.1 GyE in 7 fractions, 1 case after complete resection (R0 resection) had proton 45 GyE in 25 fractions, 5 cases after R1 resection had proton 60.0-61.6 GyE in 28-30 fractions and 1 case of recurrence after postoperative radiotherapy had only carbon ion 60 GyE in 20 fractions. Results:The median follow up time was 19.0 (2.4-42.9) months. There were 13 patients with gross tumors, with a median largest diameter of 5.7 (2.7-12.8) cm. The dosimetric study showed that proton and carbon-ion plans significantly reduced the maximum dose to the spinal cord, the mean doses to the organs at risk (OARs) including the lung/heart/esophagus, and the integral dose of the exposed area about 25%-65% compared to photon plans. No other toxicities ≥ grade 3 were observed except one myocardial infarction (grade 4 late toxicity). There was no local failure observed. Metastasis to regional lymph node, lung, pleura, skull base, bone or liver occurred in 4 patients with Ⅲ-Ⅳ B stage disease in 6.1-22.8 months after treatment. The 2-year local control and overall survival rates were 100%, disease free survival and distant metastasis free survival rates were 64.6%. Conclusions:For TMs, PT has significant advantages over photon in terms of sparing OARs, and is safe and effective in patients with TMs after short-time follow-up.
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Objective To observe the short-term effect and toxicities after carbon ion radiotherapy (CIRT) for tracheal adenoid cystic carcinoma (TACC).Methods From March 2016 to October 2017,a total of 10 patients with TACC were treated using CIRT.Among them,three patients had recurrent disease (two after surgery,and one after brachytherapy),one received bronchoscopic cryosurgery for stage Ⅰ disease,and the other 9 had locally advanced disease (3/6 received endoscopic treatment before CIRT).All patients received CIRT using pencil-beam scanning technique.Except that the patient with recurrent disease after brachytherapy received 60 GyE/20 Fx,the patient received cryosurgery and one recurrent patient after surgery received 66 GyE/22 Fx,all other patients received 69 GyE/23 Fx.Results The median follow-up time was 5.5 (1.5-16.4) months.Among the 9 patients with gross tumors,3 patients achieved complete response,2 achieved partial response,and 4 remained stable disease per RECIST 1.1 criteria.The postcryosurgery patient remained no evidence of disease.Except 1 patient experienced grade 4 tracheal stenosis,no other grade ≥ 3 adverse effects were observed.Grade 2 acute toxicities included 1 hoarseness and 1 neutropenia,both relieved after CIRT.Hypothyroidism in one patient was the only observed grade 2 late toxicity.Conclusion CIRT is safe and effective in the management of TACC during a short-time observation.
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Objective@#To verify the safety and efficacy of IONTRIS particle therapy system (IONTRIS) in clinical implementation.@*Methods@#Between 6.2014 and 8.2014, a total of 35 patients were enrolled into this trial: 31 males and 4 females with a median age of 69 yrs (range 39-80). Ten patients had locally recurrent head and neck tumors after surgery, 4 cases with thoracic malignancies, 1 case with hepatocellular carcinoma, 1 case with retroperitoneal sarcoma, and 19 cases with non-metastatic prostate carcinomas. Phantom dose verification was mandatory for each field before the start of radiation.@*Results@#Twenty-two patients received carbon ion and 13 had proton irradiation. With a median follow-up time of 1 year, all patients were alive. Among the 16 patients with head and neck, thoracic, and abdominal/pelvic tumors, 2, 1, 12, and 1 cases developed complete response, partial response, stable disease, or disease progression, respectively. Progression-free survival rate was 93.8% (15/16). Among the 19 patients with prostate cancer, biological-recurrence free survival was 100%. Particle therapy was well tolerated in all 35 patients. Twenty-five patients (71.4%) experienced 33 grade 1 acute adverse effects, which subsided at 1 year follow-up. Six (17.1%) patients developed grade 1 late adverse effects. No significant change in ECOG or body weight was observed.@*Conclusions@#IONTRIS is safe and effective for clinical use. However, long term follow-up is needed to observe the late toxicity and long term result.
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Objective To investigate the dosimetric advantages of proton and heavy ion radiotherapy ( particle radiotherapy) for liver cancer adjacent to gastrointestinal tract. Methods Ten patients with liver cancer adjacent to gastrointestinal tract receiving radiotherapy were recruited in this study. The prescription was first given with 50 Gy ( RBE )/25 fractions to planning target volume 1 ( PTV-1 ) using proton irradiation,and then administered with 15 Gy ( RBE)/5 fractions to PTV-2 using carbon-ion irradiation. A simultaneous integrated boost regime was established using the same variables and prescription. The organ at risk ( OAR) constraints were referred to RTOG 1201. All plans were performed for dose evaluation after qualifying the OAR constraints. Results The dose coverage of 95％ of the prescribed dose ( V95) for PTV-1 from the photon plan (97.15％±4. 27％),slightly better than (96.25±6. 69％) from the particle plan (P=0. 049).The V95 of PTV-2 from the particle plan was (94.6％±6. 22％),comparable to (95.12％±3. 49％) from the photon plan (P=0. 277).The integral dose of Body-PTV-1 delivered by the particle plan was merely 39. 9％ of that delivered by the photon plan. The mean liver-GTV dose from the particle plan was only 81. 8％ of that from the photon plan. The low-dose irradiation to the stomach and duodenum from the particle plan was significantly lower than that from the photon plan. Conclusions The dose to the liver-gross tumor volume ( GTV) is the main factor limiting the increase of total dose to the tumors. When the absolute GTV in the liver is relatively large,particle radiotherapy can maintain comparable dose coverage to the tumors as the photon radiotherapy whereas significantly reduce the dose to the liver-GTV.
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Objective To evaluate the safety and efficacy of proton and carbon-ion radiotherapy (RT) for stage Ⅰ non-small cell lung cancer (NSCLC) with pencil beam scanning technique.Methods From August 2014 to December 2015,10 patients with stage Ⅰ NSCLC who were inoperable or refused surgery were treated by proton +/-carbon-ion RT.Primary lesions were irradiated using 2-4 portals with 45-degree beams.A total dose of 50-70 GyE/10 fractions,60-64 GyE/15-16 fractions,and 66-72 GyE/22-24 fractions were administered to patients based on tumor location (4 peripheral,3 middle,and 3 central lesions,respectively).Results At the last follow-up in December 2016 with the median follow-up of 18.1 (11.9-28.1) months,local control was found in all patients per CT or PET/CT scanning(6 complete response,3 partial response,and 1 stable disease).However,2 patients with local control (1 partial response and 1 stable disease) experienced a distant failure at 8.7 and 24.9 months after RT,respectively.There was no RT-related Grade 3-5 toxicity in all patients.Grade 2 toxicities were only found in 2 patients (acute skin reaction and leucopenia,respectively).At 1,3-5 months after RT,the pulmonary function tests showed a slightly increase in FVC,FEV1 and DLCO-sb compared with those before RT without statistical significance (P ＞ 0.05).Conclusions The particle RT using pencil beam scanning technique was safe,and yielded encouraging outcome for patients with stage I NSCLC who were inoperable or refused surgery.Further follow-up and prospective clinical studies are warranted in the future.
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To perform an evaluation of the on-going prospective clinical trials on particle radiation therapy and their impact on the current clinical practice as well as future clinical research and development.Furthermore,to briefly present the results of the registration trial of the IONTRIS particle therapy system at the Shanghai Proton and Heavy Ion Center.We used data from the clinicaltrials,gov and the Particle Therapy Collaborative Organization Group (PTCOG) website.After excluding retrospective and in silico studies,we examined and analyzed the prospective clinical trials for their ion type,targeting disease site,and nature.At the time of this analysis,149 prospective trials were identified on proton and carbon-ion radiation therapy,including 20 were carbon-ion and 129 trials were proton radiation focused,respectively.Except for 15 randomized phase Ⅱ/Ⅲ and Ⅲ trials,134 trials were phase 0-Ⅱ trials.Tumors from nearly all body parts were covered by the on-going trials,but trials on pediatric,GI,lung,prostate,and breast cancer account for the majority.The majority of the currently on-going trials focus on the efficacy and adverse-effects of the new dose/fractionation schemes of particle therapy as well as the use of particle therapy on new indications.Few studies invcstigate the addition of adjuvant therapy or imaging technology used in adjunct with particle therapy.Randomized trials that compare particle radiation therapy versus photon radiation is relatively uncommon.Despite the prevailing use of proton and heavy-ion radiation therapy for cancer treatment,～ 150 prospective clinical trials associated with particle radiation therapy are identified.As the majority of trials aim to investigate more efficacious dose/fractionation and the application of particle therapy on new indications,improved outcome from and expanded utilization of particle radiation therapy can be expected.
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AIM:We investigated how AT 1-R stimulated by mechanical stresses induces cardiac fibrosis .METHODS:We produced in vivo cardiac pressure overload model in angiotensinogen knockout ( ATG-/-) mice and in vitro mechanically-stretched cell model in cultured neonatal cardiac cells of ATG-/-mice both lack the participation of Ang II .RESULTS: Pressure overload for 4 weeks in ATG-/-mice induced myocardial hypertrophy accompanied by the significant interstitial fibrosis , however , the TGF-β, a key regulatory factor of fibrosis, was not significantly increased in these ATG-/-mice.Meanwhile, the inhibitor for AT1-R significantly inhibited mechani-cal stress-induced cardiac fibrosis in these ATG-/-models whereas inhibition of TGF-βdid not.CONCLUSION:The results showed that mechanical stress-induced fibrotic responses through AT 1-R required the phosphorylation of Smad 2 but not the involvement of TGF-β.
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Background and purpose:Clinical data show that Endostar, a recombinant human endostatin, has the therapeutic beneift for patients with non-small cell lung cancer (NSCLC) while combined with chemotherapy or ra-diotherapy. However, the microenvironment changes induced by Endostar monotherapy in NSCLC is not yet clear. The purpose of this study was to prospectively study tumor vascular effects of Endostar monotherapy in patients with locally advanced or advanced NSCLC by dynamic contrast-enhanced perfusion computed tomography (CT perfusion, CT-p). Methods:Previously untreated patients with histologically or cytologically conifrmed locally advanced or advanced NSCLC were eligible. All patients received daily Endostar (7.5 mg?m2) for 14 days. CT-p scans were acquired at the baseline and post-treatment. CT-p parameters, such as blood lfow (BF), blood volume (BV) and permeability surface PS (area product), were measured in all patients.Results:Of all 7 patients enrolled, four were staged asⅢB and three as stageⅣ (2 with malignant pleural effusion, 1 with brain metastasis). The median BF, BV and PS values of baseline and post-treatment were 27.1/48.9 mL/100 mL/min, 86.8/84.8 mL/100 mL and 45.0/54.0 mL/100 mL/min, respectively. After administration of Endostar for 14 days , BF showed a signiifcant increase compared with that at baseline (P=0.028), whereas no signiifcant changes were found in BV (P=0.398) and PS (P=0.237) values.Conclusion:Our results suggest that Endostar monotherapy induces a signiifcant increase in BF whereas no signiifcant difference in BV and PS.
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Background and purpose:Cancer is a common disease. Multidisciplinary approach is the best model for cancer treatment. Cancer staging is the basis for diagnosis, treatments and prediction of prognosis.The survey is to give an overview of the current application of cancer multidisciplinary approach and UICC or other international cancer staging in mainland China. We made inquiries to our Chinese oncologists’ experience of using these staging and share their comments and recommendations. For those cancers common in China, Chinese oncologists and academic societies should provide more information of staging, therapies, outcome, prognostic predictors of prognosis, etc. to make international stage systems, like UICC or AJCC, a more appropriate, accurate and acceptable guide to individual patients’ staging and treatment, to predict outcome and to facilitate clinical trials better. Methods: This survey was done from 2012 to 2013 by questionnaires. The questions were answered for 10 major cancers in China (liver cancer, esophageal cancer, nasopharyngeal carcinoma, lung carcinoma, breast cancer, gastric cancer, colorectal cancer, gynecologic cancer, prostate cancer and lymphoma). Thirty-three questionnaires have been answered by national wide hospitals including provincial cancer hospitals, district cancer hospitals and departments of oncology in general hospitals. We also site visited 7 grade B hospitals. Results:Multidisciplinary approach is not widely used in the hospitals. UICC or AJCC stages have been widely used for 10 cancers, but for cancers that were uncommon in the West;while common in China (nasopharyngeal carcinoma, liver cancer) the staging proposed by Chinese society have also been used to replace UICC/AJCC. Conclusion:We suggest a wild implementation of multidisciplinary approach. For those cancers common in China Chinese oncologists and academic societies should provide more information of staging, therapies, outcome, prognostic predictors of prognosis etc. to make international stage systems, like UICC or AJCC, a more appropriate, accurate and acceptable guide to individual patients’ staging and treatments, to predict outcome and to facilitate clinical trials better.
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Background and purpose:We investigated whether lfuorine-18 lfuorodeoxyglucose (18F-FDG) maximal standard uptake value (SUVmax) of the primary tumor (SUV-T), SUVmax of the regional lymph nodes (SUV-N) or the overall loco-regional lesion SUVmax (SUV-TOTAL) was related to survival of patients with stage Ⅲ non-small cell lung cancer (NSCLC) who received Cetuximab and combined definitive chemoradiotherpay. Methods:From September 2009 to July 2012, seventeen patients with unresectable stageⅢNSCLC receiving cetuximab with cisplatin/vinorelbine (NP) followed by concomitant NP and intensity-modulated radiotherapy (IMRT) at the Fudan University Shanghai Cancer Center were enrolled onto a prospectively study. All patients received positron emission tomography/computerized tomography (PET/CT) scans within 2 weeks before enrolment. Univariate analysis were used to assess the correlation between SUV-T, SUV-N, SUV-TOTAL, gender, age, histology, tumour-node-metastasis (TNM) stage, performance status (PS) as well as smoking status and survival. The factors which showed statistical signiifcance entered into multivariate Cox-regression model. Survival functions of different populations were estimated by Kaplan-Meier method and compared by Log-rank test. Results:In the univariate analysis, SUV-T, SUV-N, SUV-TOTAL, PS and smoking status were prognostic factors. The best cut-off values for SUV-T, SUV-N and SUV-TOTAL were 11, 11 and 20, respectively. Multivariate analysis revealed that SUV-TOTAL (P=0.012), SUV-T (P=0.025), and SUV-N (P=0.033) were independent predictors of survival with hazard ratio (HR) of 14.7, 11.2, and 6.2, respectively. Conclusion:Local, regional and locoregional maximal SUVs deifned by 18F-FDG PET-CT scanning may have a strong correlation with survival in this patients setting, which merits further study.
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Objective To assess the rotational set-up errors in patients with thoracic neoplasms. Methods 224 kilovohage cone-beam computed tomography (KVCBCT) scans from 20 thoracic tumor pa-tients were evaluated retrospectively. All these patients were involved in the research of " Evaluation of the residual set-up error for online kilovohage cone-beam CT guided thoracic tumor radiation". Rotational set-up errors, including pitch, roll and yaw, were calculated by 'aligning the KVCBCT with the planning CT, using the semi-automatic alignment method. Results The average rotational set-up errors were -0.28°±1.52°, 0.21°± 0.91° and 0.27°± 0. 78° in the left-fight, superior-inferior and anterior-posterior axis, respective-ly. The maximal rotational errors of pitch, roll and yaw were 3.5°, 2.7° and 2.2°, respectively. After cor-rection for translational set-up errors, no statistically significant changes in rotational error were observed. Conclusions The rotational set-up errors in patients with thoracic neoplasms were all small in magnitude. Rotational errors may not change after the correction for translational set-up errors alone, which should be e-valuated in a larger sample future.
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Objective To investigate the accuracy of image registration with computed tomograpby (CT) and magnetic resonance imaging(MRI) and to determine gross tumor volume(GTV) of hepatocellular carcinoma(HCC).Methods Thirteen patients were enrolled in this study.CT image was taken in inhala tion phase,and MRIT2 image at the time of peak exhalation.Additional MRIT2 image was taken by fast scanning(MRIT2F) in peak inhalation phase in 6 patients.After mutual information method to CT/MRI im age registration,manual adjustment was made to optimize the accuracy of image fusion.The GTV and liver of each patient was independently contoured by two observers on CT,MRIT2 and MRIT2F images.The accura oy of image fusion was assessed by the ratio of liver overlap(P-LIVERCT-MRIAT2 ,P-LIVERCT-MRIT2F) ,and the dis tance between bone markers(DCT-MRIT2,DCT-MRIT2F) of CT and MRI on the fused image.The volumes of GTV contoured on CT (V-GTVCT),MRIT2 (V-GTVMRIT2),MRIT2F (V-GTVMRIT2F) and their overlap (V GTVCT-MRIT2,V-GTVCT-MRIT2F) and composite volumes (V-GTVCT+MRIT2,V-GTVCT+MRIT2F)were measured.The percentage of V-GTVCT and V-GTVMRIT2 on V-GTVCT+MRIT2,V-GTVCT and V-GTVMRIT2F on V-GTVCT+MRIT2F,V GTVCTMRIT2 and V-GTVCT-MRIT2F on V-GTVCT was also calculated,respectively.Results The mean DCT-MRIT2 and DCT-MRIT2F were 2.7±0.8 mm and 2.1Q±0.9mm.The mean P-LIVERCT-MRIT2 and P-LIVERCT-MRIT2F were 85.9% ± 4.1% and 92.7%± 1.5%.Interobserver difference was significant for GIN defined by CT,but not by MRIT2.V-GTVCT,V-GTVMRIT2 and V-GTVMRIT2F were 387±396 cm3 ,488 ±461 cm3 and 597 ±541 cm3 ,respectively.The percentage of V-GTVCT and V-GTVMRIT2 on V-GTVCT+MRIT2 was 66.2%±13.5% and 88.7% ± 10.2% ,while V-GTVCT and V-GTVMRIT2F on V-GTVCT-MRIT2F was 71.3%±12.7% and 93.5%± 4.8%,respectively.Conclusions CT and MRI for image fusion should be obtained in the same respirato ry phase and in the same treatment position.Automatic registration using mutual information method by auto matic registration software is useful.CT and MRI image should be integrated for HCC GTV delineation.GTV used for planning should be the sum of CT-defined GTV and MRl-defined GTV.
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Objective To select the optimal registration method for on-line kilovoltage cone-beam CT (KVCBCT) guided lung cancer radiation and evaluate the reproducibility of the selected method. MethodsSixteen patients with non-small cell lung cancer were enrolled into this study.A total of 96 pre treatment KVCBCT images from the 16 patients were available for the analysis.Image registration methods were bone-based automatic registration,gray-based automatic registration,manual registration and semi-auto matic registration.All registrations were accomplished by one physician.Another physician blindly evaluated the results of each registration,then selected the optimal registration method and evaluated its reproducibili ty.Results The average score of the bone-based automatic registration,gray-based automatic registration, manual registration and semi-automatic registration methods was 2.4,2.7,3.0 and 3.7,respectively.The score of the four different groups had statistics significant difference (F = 42.20,P < 0.001).Using the semi-automatic registration method,the probability of the difference between two registration results more than 3 ram in the left-right,superior-inferior,and anterior-posterior directions was 0,3% and 6% by the same physician,0,14% and 0 by different physicians,and 8%,14% and 8% by physician and radiation therapist.Conclusions Semi-automatic registration method,possessing the highest score and accepted re producibility,is appropriate for KVCBCT guided lung cancer radiation.
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Objective To quantitatively analyze the image quality of megavoltage cone-beam CT (MVCBCT) under different scanning conditions to provide reference in clinical applications. Methods Si-emens ONCOR linear accelerator with MVCBCT was used to scan the phantom under different conditions. The image quality was evaluated in terms of image noise, uniformity, spatial resolution, contrast resolution, the number of Monitor Units(MUs) used in imaging,and the size of the reconstruction matrix. The comparison of the image quality between MVCBCT and conventional simulator CT was also analyzed. Results The image noise was decreased with the increase of the number of MUs. The uniformity index showed that the system u-niformity was weakly dependent on MU numbers or the size of the reconstruction matrix. Except for the ima-ges with 5 MUs,all other images had the spatial resolution of 0.4 lp/mm with a reconstruction matrix of 256 ×256. Better low contrast resolution was achieved by using more MUs. For typical pelvis and head-and-neck patients,the imaging dose at the center was 0.8 cGy/MU and 0.7 cGy/MU, respectively,and the maxi-mum dose was about 1.2 cGy/MU. For typical abdomen patients,the image maximum dose and center dose was 1.3 cGy/MU and 0.7 cGy/MU,respectively. Conclusions The image quality of MVCBCT is inferior to the conventional kilo-voltage CT. However,with the optimization of the parameters in imaging,we can a-chieve sufficient image contrast in the bone,air and some soft-tissue structures with low imaging dose to pa-tients. Such images can be used for IGRT.
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Objective To investigate dose characteristics of megavoltage cone-beam CT in the low MU and rotation way for imaging,and to improve the quality assuraflce. Methods Dose linearity,a parameter describing beam characteristics,was measured for different numbers of MUs on megavoltage conebeam CT accelerator.Dose stability was measured 5 times using exposure of 7 MUs,which was repeated another 5 times 6 hours after. Results Dose linearity was good using exposure between 5 and 20 MUs.The average dose among the first and second 5 measurements was(5.74±0.01)Gy and(5.76±0.01)Gy while exposure of the accelerator was 7 MU.The difference between the two doses was 0.41%. he dose was stability while megavoltage cone-beam CT image was in the low MU and rotation way. Conclusion Dose characteristics of megavoltage cone-beam CT in the low MU and rotation way for imaging can qualify clinically application.
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Objective To evaluate the accuracy, of different threshold segmentation of 18FDG PET for target volume delineation of non-small cell lung cancer(NSCLC) and the potential influence on radiotherapy treatment planning. Methods Eight NSCLC patients who had tumor with clear margin on CT scan and the amplitude of tumor movements not more than 5 mm were enrolled. PET scans were carried out at 1 h after intravenous injection of 18FDG with CT image for attenuation revisement. Gross target volume (GTV) delineated on CT image ( GTVCT ) was used as the standard. Then, GTVs were delineated on PET image with three different threshold segmentation of 42% Imax(total) (42% of maximum voxel intensity within the tumor) ,Iback + 20% Imax-back(max) (mean background intensity + 20% of normalized background-subtracted maximum voxel intensity within the tumor) and Iback -20% Imax-back(slice) (mean background intensity + 20% of normalized background-subtracted maximum voxel intensity of each slice within the tumor) ,the corresponding GTV was named as GTV42%, GTV20%max and GTV20%slice. Both the size of GTV42%, GTV20%max, GTV20%slice and GTVCT,and the coverage over GTVCT for each GTV were compared. A three dimensional margin of 1 cm were added to GTVCT, GTV42%, GTV20%max and GTV20%slice to form corresponding PTVCT, PTV42%, PTV20%max and PTV20%slic e. Three dimensional conformal radiotherapy treatment plans were designed based on PTVCT,PTV42% , PTV20%max and PTV20%slice respectively for each patient. The prescription dose of all PTVs was 66 Gy in 33 fractions in 6.6 weeks. Both the volume accepting dose less than 95% of prescription dose within PTVCT ( VPTV ) and the lung V20 were compared among the four plans based on different PTVs. Tumor control probability(TCP) as well as lung normal tissue complication probability (NTCP) were also compared. Resuits Eight patients were enrolled in this study. Median deviation of volume between GTVPET and GTVCT were -54.1% , -21.5 % and 5.3 % for GTV42% , GTV20%max and GTV20%slice, respectively. Median coverage over GTVCT of GTV42% , GTV20%max and GTV20%slice was 45.9% ,78.0% and 95.3% respectively( F = 57.50,P＜0.01). Median 7.5% of VPTV was observed for radiotherapy treatment plan based on PTV42% ,which meant that it might induce median 1% decrease of TCP comparing with that of radiotherapy treatment plan based on PTVCT. Whereas,there were only 1.3% and 0.0% of VPTV for treatment plans based on PTV20%max and PTV20%slice respectively. As far as TCP was concemed, both PTV20%max group and PTV20%slice group were superior to PTV42% group,there was no significant difference among PTV20%max group, PTV20%slice group and PTVCT group. Lung V20 and lung NTCP showed no significant difference among all groups. Conclusions The threshold segmentation of Iback + 20% Imax-back(slice) , being slice specialized, might be an optimal threshold segmentation for target volume delineation of lung caner. Independent of information of target volume provided by CT scan in advance,it is recommended to use for the target volume delineation of NSCLC with atelectasis.