Ergebnisse der Österreichischen CT-Dosisstudie 2010: Effektive Dosen der häufigsten CT-Untersuchungen und Unterschiede zwischen Anwendern

PurposeTo determine typical doses from common CT examinations of standard sized adult patients and their variability between CT operators for common CT indications.Materials and MethodsIn a nationwide Austrian CT dose survey doses from approx. 10,000 common CT examinations of adults during 2009 and 2010 were collected and ?typical“ radiation doses to the “average patient”, which turned out to have 75.6 kg body mass, calculated. Conversion coefficients from DLP to effective dose were determined and effective doses calculated according to ICRP 103. Variations of typically applied doses to the “average patient” were expressed as ratios between 90^th and 10^th percentile (inter-percentile width, IPW90/10), 1^st and 3^rd quartile (IPW75/25), and Maximum/Minimum.ResultsMedian effective doses to the average patients for standard head and neck scans were 1.8 mSv (cervical spine), 1.9 mSv (brain: trauma/bleeding, stroke) to 2.2 mSv (brain: masses) with typical variation between facilities of a factor 2.5 (IPW90/10) and 1.7 (IPW75/25). In the thorax region doses were 6.4 to 6.8 mSv (pulmonary embolism, pneumonia and inflammation, oncologic scans), the variation between facilities was by a factor of 2.1 (IPW90/10) and 1.5 (IPW75/25), respectively. In the abdominal region median effective doses from 6.5 mSv (kidney stone search) to 22 mSv (liver lesions) were found (acute abdomen, staging/metastases, lumbar spine: 9-12 mSv; oncologic abdomen plus chest 16 mSv; renal tumor 20 mSv). Variation factors between facilities were on average for abdominal scans 2.7 (IPW90/10) and 1.8 (IPW75/25).ConclusionVariations between CT operators are generally moderate for most operators, but in some indications the ratio between the minimum and the maximum of average dose to the typical standard patients exceeds a factor of 4 or even 5. Therefore, comparing average doses to Diagnostic Reference Levels (DRLs) and optimizing protocols need to be encouraged.     

Meningeosis leukaemica in adult acute lymphoblastic leukaemia

This review addresses diagnosis of CNS involvement, incidence and treatment of CNS disease at time of diagnosis, prophylaxis and treatment of CNS relapse and risk factors for meningeal recurrence in adult acute lymphoblastic leukaemia (ALL).At the time of diagnosis meningeosis leukaemica is present in about 6% (1–10%) of the adult ALL patients with a higher incidence in ALL subgroups T-ALL (8%) and B-ALL (13%). With the invention of early additional CNS directed therapy it no longer represents an unfavourable prognostic factor.In the absence of prophylaxis meningeal relapses occur in approximately one third of adults with ALL. A literature review including more than 4000 adult ALL patients showed for the different prophylactic treatment approaches the following CNS relapse rates: intrathecal therapy alone 13% (8–19%), intrathecal therapy and CNS irradiation 15% (6–22%), high dose chemotherapy 14% (10–16%), high dose chemotherapy and intrathecal therapy 8% (2–16%) and high dose chemotherapy, intrathecal therapy together with CNS irradiation 5% (1–12%). It became obvious that the early onset of intrathecal therapy and CNS irradiation and the continuation of intrathecal administrations throughout maintenance are essential. The most favourable results where achieved with high dose chemotherapy combined with intrathecal therapy and/or CNS irradiation. The majority of treatment regimens in adult ALL already include high dose chemotherapy in order to reduce the risk of bone marrow relapse.The outcome of patients with CNS relapse is still poor. Although a remission can be induced in the majority of patients (> 60%) it is usually followed by a bone marrow relapse and the survival is poor (< 5–10%). Bone marrow transplantation might be in adults at present the only curative approach.     

Action Levels on Dose and Anatomic Variation for Adaptive Radiation Therapy Using Daily Offline Plan Evaluation: Preliminary Results

Purpose

This study aimed to develop action levels for replanning to accommodate dosimetric variations resulting from anatomic changes during the course of treatments, using daily cone beam computed tomography (CBCT).

Efficacy and safety of ultrasound-guided totally implantable venous access ports via the right innominate vein in adult patients with cancer: Single-centre experience and protocol

BackgroundTotally implantable venous access ports (TIVAPs) are widely used and are an essential tool in the efficient delivery of chemotherapy. This study aimed to evaluate the feasibility and safety of implantation of ultrasound (US)-guided TIVAPs via the right innominate vein (INV) for adult patients with cancer.MethodsThis study retrospectively reviewed the medical records of 283 adult patients with cancer who underwent US-guided INV puncture for TIVAPs between September 2015 and September 2017. It also analysed the technical success rate, operation time, and short-term and long-term surgical complications.ResultsTechnical success was achieved in all patients (100%). The mean operation time was 28.31 ± 7.31 min (range: 23–39 min), and the puncture success rate for the first attempt was 99.30% (281/283). Minor complications included artery puncture during the operation in one patient, but no pneumothorax was encountered. The mean TIVAP time was 304.16 ± 42.54 days (range: 38–502 days). The rate of postoperative complications was 2.83% (8/283), including poor healing of the incision in one patient, catheter-related infections in three patients, port thrombosis in one patient, and fibrin sheath formation in three patients; no catheter malposition, pinch-off syndrome, catheter fracture, or other serious complications were observed.ConclusionsTIVAPs are widely employed for chemotherapy. The present study found that the novel approach of using US-guided INV puncture to implant TIVAPs in adult patients with cancer is both short-termly feasible and safe for long-term central venous access.     

Accuracy and precision of cone-beam computed tomography guided intensity modulated radiation therapy

PurposeTo assess the accuracy and precision of cone-beam computed tomography (CBCT)-guided intensity modulated radiation therapy (IMRT).Methods and MaterialsA 7-field intensity modulated radiation therapy plan was constructed for an anthropomorphic head phantom loaded with a custom cassette containing radiochromic film. The phantom was positioned on the treatment table at 9 locations: 1 “correct” position and 8 “misaligned” positions along 3 orthogonal axes. A commercial kilovoltage cone-beam computed tomography (kV-CBCT) system (VolumeView, Elekta AB, Stockholm, Sweden) was then used to align the phantom prior to plan delivery. The treatment plan was delivered using the radiation therapy delivery system (Infinity; Elekta AB) 3 times for each of the 9 positions, allowing film measurement of the delivered dose distribution in 3 orthogonal planes. Comparison of the planned and delivered dose profiles along the major axes provided an estimate of the accuracy and precision of CBCT-guided IMRT.ResultsOn average, targeting accuracy was found to be within 1 mm in all 3 major anatomic planes. Over all 54 measured dose profiles, the means and standard errors of the displacement of the center of the field between the measured and calculated profiles for each of the right-left, anterior-posterior, and superior-inferior axes were + 0.08 ± 0.07 mm, + 0.60 ± 0.08 mm, and + 0.78 ± 0.16 mm, respectively. Agreement between planned and measured 80% profiles was less than 0.4 mm on either side along the right-left axis. A systematic shift of the measured profile of slightly less than 1 mm in anterior and superior directions was noted along the anterior-posterior and superior-inferior axes, respectively.ConclusionsSubmillimeter targeting accuracy can be achieved using a commercial kV-CBCT IGRT system.     

A Novel Liquid Fiducial Marker in Esophageal Cancer Image Guided Radiation Therapy: Technical Feasibility and Visibility on Imaging

PurposeTo assess the technical feasibility of injection, visibility on imaging modalities, and positional stability of a novel liquid fiducial marker (ie, BioXmark) for radiation therapy in patients with esophageal cancer.MethodsFirst, the visibility on imaging of different volumes of the liquid marker was analyzed ex vivo in porcine tissue (ie, on computed tomography [CT], cone beam CT (CBCT), and magnetic resonance imaging [MRI]). Next, for the in vivo part, the liquid fiducial markers were injected under endoscopic (ultrasound) guidance in 10 patients with curable esophageal cancer. The technical feasibility of the injection procedure and the clinical performance (ie, visibility and positional stability on imaging) were evaluated. Planning CT, daily CBCT, and serial MRI images (before, during, and after chemoradiation therapy in a subset of 3 patients) were acquired.ResultsEx vivo, the optimal volume for good visibility without artifacts was 0.1 mL per injected marker. In vivo, a total of 28 markers were injected in 10 patients (range, 0.025-0.1 mL). No adverse effects were identified. The first 2 cases (4 markers) were considered as learning cases. A total of 19 of 24 of the liquid markers (79%) were visible on CT, 3 of 4 (75%) on MRI, and 19 of 24 (79%) on the first CBCT. All markers with an injected volume of >0.05 mL were visible on the different imaging modalities. Positional stability analysis on CBCT identified no time trend during the radiation therapy course. No artifacts could be detected for liquid marker volumes of 0.05 and 0.025 mL in CT or CBCT.ConclusionsInjection of a liquid fiducial marker for esophageal cancer radiation therapy is technically feasible with no adverse events identified. Volumes of >0.05 mL have an appropriate visibility on CT, CBCT, and MRI, with an excellent positional stability. Liquid fiducial markers are therefore promising for use in image guided radiation therapy.     

The Feasibility and Utility of Cystoscopy-Guided Hydrogel Marker Placement in Patients With Muscle-Invasive Bladder Cancer

PurposeFiducial markers at the borders of bladder tumors are useful to facilitate target delineation radiation therapy (RT) and offer the possibility of image guided RT for a focal boost. Our purpose was to evaluate the feasibility and technical performance of cystoscopy-guided placement of hydrogel markers in patients with bladder cancer referred for RT.Methods and MaterialsOurs was a prospective, multicenter, feasibility, and utility study. Thirty-two consecutive patients with muscle-invasive bladder cancer, referred for RT, underwent cystoscopy-guided implantation of hydrogel markers. Feasibility, clinical performance of the markers, and adverse events were registered. Computer tomography (CT) scans and cone beam CT (CBCT) scans acquired during RT were analyzed to evaluate the visibility and stability of the markers during the radiation period.ResultsA total of 107 hydrogel spots were implanted in 32 patients with bladder cancer. There were no procedure-related adverse events. On the simulation CT scan 76.6% of the implanted markers were sufficient for tumor delineation. At start of treatment 52.3% were visible on the CBCT and adequate for positional verification on a routine basis. The washout rate during treatment was 9.3%. At the end of treatment 46.7% of implanted spots were visible on CBCT scan and adequate for routine positional verification. At patient level, in 31.2% of cases, use of hydrogel fiducials showed adequate performance throughout the whole course.ConclusionsCystoscopy-guided placement of hydrogel markers is both safe and feasible for muscle-invasive bladder tumors. Adequate performance for radiation purposes throughout the whole course (implantation, delineation, and positional verification) was 46.7% of all implanted markers, leaving room for improvement.     

Analyzing the Possibility of Utilizing CBCT Radiomics as an Independent Modality: A Phantom Study

Aim:To verify if computed tomography (CT) radiomics were reproducible by cone beam CT (CBCT) radiomics by using Catphan^® 504. Materials and Methods:Catphan^® 504 was imaged using the default IGRT OBI CBCT imaging protocols and CT scanner. Seven known density image regions of the phantom were segmented and image feature was extracted by Imaging Biomarker Explorer (IBEX) software. The 49 selected features from four feature categories were analyzed by considering each region of interest (ROI) segment as individual image set. Correlation was studies using interclass correlation coefficient (ICC) and Pearson’s correlation coefficient. Results:The ICC of the three feature categories, namely intensity, GLCM, and GLRLM was significant (p-value<0.05) in comparison with CT, while the ICC of the fourth feature category, NID, was no significant. The average absolute Pearson’s correlation coefficient from the features of the images was as follows: CT: r=0.679±0.257, CBC_Thead: r=0.707±0.231, CBCT_thorax: r=0.643±0.260, and CBCT_pelvis: r=0.594±0.276. Conclusion: It seems that the various densities of Catphan^® 504 ROI image segments of the CT radiomics are reproducible with CBCT radiomics and CBCT radiomics can be used as an independent modality. Key Words: Texture, quantitative imaging features, cone-beam CT, computed tomography     

Post-prostatectomy image-guided radiation therapy: evaluation of toxicity and inter-fraction variation using online cone-beam CT

Purpose: The purpose of this study is to assess the acute and late genitourinary (GU) and gastrointestinal (GI) toxicities of cone‐beam computed tomography (CBCT) guided conformal adjuvant and salvage post‐prostatectomy radiotherapy (RT) compared with RT with port films. Materials and methods: Sixty‐eight patients (group 1) were treated with RT following radical prostatectomy (RP) using CBCT‐guided conformal RT to a median dose of 68.4 Gy. CBCT images were acquired three to five times weekly and were automatically co‐registered to a reference CT. A comparative group (group 2) included 150 patients who received post‐RP RT with weekly port films to a median dose of 64.8 Gy. GU and GI toxicities were graded in both the acute and late settings using Radiation Therapy Oncology Group criteria. Associations between toxicity and study variables were evaluated by odds ratios (ORs) estimated by logistic regression. Results: Grades 2 and 3 acute GU toxicity were experienced by 13% (n = 9) and 2% (n = 1) of patients in group 1, respectively, while 13% (n = 19) had grade 2 acute GU toxicity in the control group (group 2). Grade 2 acute GI toxicity was experienced by 13% (n = 9) and 15% (n = 23) in groups 1 and 2, respectively. Acute GU (P = 0.67) and GI (P = 0.84) toxicities were not significantly different between the two groups. There were no associations detected between CBCT and acute GI toxicity (OR 0.76, P = 0.57) or acute GU (OR 1.16, P = 0.75). Increased odds of acute GU toxicity were observed for doses > 68.4 Gy (OR 12.81, P = 0.04), which were only delivered in the CBCT group. CBCT mean variations (standard deviation) for 1053 fractions were 2.8 mm (2.8), 2.0 mm (2.4) and 3.1 mm (2.9) in the left‐to‐right, anterior‐to‐posterior (AP) and superior‐to‐inferior (SI) axes, respectively. Corrective shifts for variance ≥ 5 mm were required for 15%, 6% and 19% of fractions in the left‐to‐right, anterior‐to‐posterior and superior‐to‐inferior axes, respectively. Conclusions: Rates of acute toxicity with CBCT‐guided post‐RP RT to 68.4 Gy were similar to treatment to 64.8 Gy without image‐guidance RT. Acceptable early toxicity profiles suggest that CBCT is a reasonable strategy for image guidance, but the value of CBCT must be weighed against potential increased risk of secondary cancers due to increased radiation exposure.     

Post-operative wall shear stress in the superior mesenteric artery: Biomarker of long term outcome in patients with residual disease after incomplete cytoreductive surgery for pseudomyxoma peritonei

BackgroundAfter incomplete cytoreductive surgery (CRS), the assessment of pseudomyxoma peritonei (PMP) progression remains challenging. The objective was to assess the efficacy of wall shear stress (WSS) measured in superior mesenteric artery (SMA) to predict PMP progression in the postoperative setting to propose additional treatments.MethodsIn a prospective study, 52 patients with PMP had Doppler-ultrasound examination of the SMA with WSS calculation within one year after CRS with a mean follow-up of 43.3 ± 18.3 months. Patients were categorized according to the completeness of CRS and clinical outcome: Group-1 (n = 19): complete CRS and no recurrence, group-2 (n = 20): incomplete CRS with slowly progressive disease (alive at 2 years without severe clinical symptoms), group-3 (n = 13): incomplete CRS and severe clinical symptoms or dead within two years. Results of WSS were compared between groups and to 24 healthy subjects.ResultsWSS measured in the SMA was superior in Group-3 (19.6 ± 8.2 dynes/cm²) than in Group-2 (9.2 ± 1.8 dynes/cm², p = 1.10⁻⁶), Group-1 (10.4 ± 2.8 dynes/cm², p = 8.10⁻⁵), and healthy patients (8.7 ± 2.8 dynes/cm², p = 9.10⁻⁷). One year after surgery, among patients with incomplete CRS a cut-off value of 12.1dynes/cm² allowed distinguishing patients without from those with severe disease progression with a sensitivity of 100% and a specificity of 100% (p < 1.10⁻⁴) AUC = 1.000 [95%CI: 0.897–1.000].ConclusionPost-operative assessment of the WSS in the SMA in patients with incomplete CRS for PMP should be considered as biomarker of tumor progression in the postoperative setting. Therefore, WSS could be useful to target patients needing adjuvant systemic chemotherapy one year after CRS.     

Safety and Efficacy of Drug-eluting Microspheres Chemoembolization under Cone Beam Computed Tomography Control in Patients with Early and Intermediate Stage Hepatocellular Carcinoma

BackgroundDrug-eluting microsphere transarterial chemoembolization (DEM-TACE) is the standard of care in patients with intermediate-stage hepatocellular carcinoma and ensures targeted and controlled cytotoxic and ischemic effects. Proper patient selection and optimized treatment techniques are associated with longer median survival. The aim of this single-institution retrospective study was to evaluate safety and efficacy of DEM-TACE under cone beam computed tomography (CBCT) control in patients with early and intermediate stage hepatocellular carcinoma.Patients and methodsA total of 144 patients (mean age 67.9 ± 8.0 years, 127 males and 17 females) between February 2010 and December 2018 were studied. Microparticles of different dimensions according to two manufacturers (diameter of 70–150 μm, 100–300 μm or 300–500 μm and 40-μm, 75-μm or 100-μm) were used and loaded with 50–150 mg of doxorubicin. The objective tumour response according to the modified Response Evaluation Criteria in Solid Tumours (mRECIST), the time to progression, adverse events and overall survival were (OS) evaluated.ResultsIn total, 452 procedures were performed (median, 3 per patient). Four (0.9% of all procedures) major complications were noted. Postembolization syndrome occurred after 35% of procedures. At the first imaging follow-up 2–3 months after first treatment, 91% of patients achieved an objective response. The median time to progression was 10.2 months (95% CI: 8.3-12.1 months). OS rates at 1, 2, 3, 4, and 5 years were 85%, 53%, 33%, 20% and 14%, respectively. The median survival time was 25.8 months (95% CI: 22.1–29.5 months).ConclusionsDEM-TACE under CBCT control in patients with early and intermediate stage hepatocellular carcinoma is a safe and effective method of treatment with high objective tumour response and survival rates.Key words: hepatocellular carcinoma, drug-eluting microspheres, doxorubicin, transarterial chemoembolization, cone beam computed tomography, safety, efficacy     

Features of colorectal cancer in China stratified by anatomic sites: A hospital-based study conducted in university-affiliated hospitals from 2014 to 2018

ObjectiveThe clinical and biological characteristics of colorectal cancer have been found to differ depending on the anatomic site of the cancer. However, for Chinese patients, there is limited information on the proportion of cases at each site and the related features. In this study, we explored the location, distribution and other features of colorectal cancers at each anatomic site in Chinese patients.MethodsWe conducted a hospital-based study using hospitalization summary reports from 10 Peking University-affiliated hospitals from 2014 to 2018; the reports covered a total of 2,097,347 hospitalizations. Incident cases were chosen as the study population, and their epidemiological features were further analyzed.ResultsA total of 20,739 colorectal cancer patients were identified. Rectum was the most common location (48.3%) of the cancer, whereas the proportions of patients with distal and proximal colon cancer were 24.5% and 18.6%, respectively. Patients with rectal cancer were predominantly male and were the youngest for all anatomical sites (each P<0.001). The highest proportion of emergency admissions, the longest hospital stays and the highest hospitalization costs were found in patients with proximal colon cancer (each P<0.001). The proximal colon cancer subgroup included the highest proportions of patients with medical histories of cholecystectomy, cholecystolithiasis and/or gallbladder polyps and appendectomy (P=0.009, P<0.001 and P<0.001, respectively). The distal colon cancer subgroup included the highest proportions of patients with medical histories of diabetes and hypertension (P<0.001, respectively).ConclusionsThe patterns of colorectal cancer observed in this study differ from those reported for Western patients and show a significantly higher proportion of patients with rectal cancer. Different epidemiological features were also found based on anatomic sites. Further studies based on tumor location should be conducted to facilitate more accurate screening and treatment.     

Clinical use of dual image-guided localization system for spine radiosurgery

The recently released Novalis TX linac platform provides various image guided localization methods including a stereoscopic X-ray imaging technique (ExacTrac) and a volumetric cone beam computed tomography (CBCT) imaging technique. The ExacTrac combined with the robotic six dimensional (6D) couch provides fast and accurate patient setup based on bony structures and offers "snap shot" imaging at any point during the treatment to detect patient motion. The CBCT offers a three dimensional (3D), volumetric image of the patient's setup with visualization of anatomic structures. However, each imaging system has a separate isocenter, which may not coincide with each other or with the linac isocenter. The aim of this paper was to compare the localization accuracy between Exactrac and CBCT for single fraction spine radiosurgery treatments. The study was performed for both phantom and patients (96 clinical treatments of 57 patients). The discrepancies between the isocenter between the ExacTrac and CBCT in four dimensions (three translations and one rotation) were recorded and statistically analyzed using two-tailed t-test.     

锥形束CT引导下应用SBRT治疗早期非小细胞肺癌疗效观察

目的:评价锥形束CT（cone beam CT,CBCT）引导下应用立体定向放射治疗（stereotactic body radiation therapy,SBRT）治疗早期非小细胞肺癌的近期疗效及毒副反应。方法:选取17例I期非小细胞肺癌患者接受CBCT引导下的SBRT胸部放疗,SBRT处方剂量DT 60 Gy/12 f,5次/周,95%以上计划靶区（PTV）满足处方剂量,90%等剂量线包含整个靶区,严格控制各危及器官剂量:双肺V5＜50%、V20＜20%,脊髓Dmax＜25 Gy,心脏Dmean＜27 Gy等。每次照射前均行CBCT扫描并在线匹配、校准。结果:所有患者均完成放疗并随访3～24个月（中位随访期18个月）,其中完全缓解（CR）4例,部分缓解（PR）12例,稳定（SD）1例,无进展患者,总有效率为94.1%。1年局部控制率和生存率分别为100%和100%。2年局部控制率和生存率分别为88.2%和82.3%。放疗期间未出现III级以上严重的放射性毒副反应。结论:应用CBCT引导下行SBRT治疗早期非小细胞肺癌,可显著提高其局部控制率和生存率,毒副反应较轻,但其远期疗效及晚期毒副反应仍待进一步随访观察。     

CBCT引导前列腺癌IMRT图像配准及靶区外放边界分析

目的 通过分析千伏级CBCT引导前列腺癌IMRT的数据,为选择合理的图像配准方法和适宜的外放边界提供临床依据。方法 针对 16例接受根治性IMRT的前列腺癌患者,共行CBCT在线校正治疗体位214次。采用常规皮肤标记激光对位后采集图像,将所获得CBCT图像与计划CT图像进行默认自动配准、骨性配准、软组织配准及手动靶区配准。比较4种配准方式之间差异,并计算由CTV外放产生PTV间距。结果 16例患者默认自动配准、骨性配准、软组织配准及手动靶区配准方式在左右、前后、上下方向平移摆位误差分别为(-0.6±2.8)、(-0.6±4.5)、(-0.6±3.8) mm,(-0.7±2.7)、(-0.9±4.5)、(-0.8±4.1) mm,(-0.8±2.6)、(-0.3±4.4)、(-1.1±4.0) mm,(-0.6±2.9)、(-0.7±5.1)、(-0.9±3.9) mm。经分析4种配准方式之间相近。PTV在左右、前后、上下方向外放间距分别为4.7、5.2、6.5 mm。结论 综合各种因素考虑,应用在线默认自动配准+手动微调CBCT引导放疗技术治疗前列腺癌患者更为合适。PTV安全外放边界在左右、前后、上下方向分别为4.7、5.2、6.5 mm。     

Computed tomography-guided percutaneous microwave ablation of hepatocellular carcinoma in challenging locations: safety and efficacy of high-power microwave platforms

Objective: To evaluate the clinical efficacy/safety of CT-guided percutaneous microwave ablation for HCC in challenging locations using high-power microwave platforms.

Materials and methods: A retrospective review was conducted in 26 patients with 36 HCC tumours in challenging locations (hepatic dome, subcapsular, close to the heart/diaphragm/hepatic hilum, exophytic) undergoing CT-guided percutaneous microwave ablation in a single centre since January 2011. Two different microwave platforms were used both operating at 2.45?GHz: AMICA and Acculis MWA System. Patient demographics including age, sex, tumour size and location, as well as technical details were recorded. Technical success, treatment response, patients survival and complication rate were evaluated.

Results: Treated tumours were located in the hepatic dome (n?=?14), subcapsularly (n?=?16), in proximity to the heart (n?=?2) or liver hilum (n?=?2), while two were exophytic tumours at segment VI (n?=?2). Mean tumour diameter was 3.30?cm (range 1.4–5?cm). In 3/26 patients (diameter?>4?cm), an additional session of DEB-TACE was performed due to tumour size. Technical success rate was 100%; complete response rate was recorded in 33/36 tumours (91.6%). According to Kaplan–Meier analysis, survival rate was 92.3% and 72.11% at 24- and 60-month follow-up, respectively. There were no major complications; two cases of minor pneumothorax and two cases of small subcapsular haematoma were resolved only with observation requiring no further treatment.

Conclusion: CT-guided percutaneous microwave ablation for hepatocellular carcinoma tumours in challenging locations and up to 5?cm in diameter can be performed with high efficacy and safety rates.     

千伏级CBCT图像引导椎体肿瘤放疗摆位误差分析

目的:研究千伏级CBCT图像引导椎体肿瘤放疗摆位误差的研究。方法:采用瓦里安IX直线加速器机载影像系统对37例椎体肿瘤患者调强放疗前行CBCT,系统自动重建图像并与治疗计划CT图像相匹配,获得患者X轴(左右）、Y轴（头脚）、Z轴（前后）方向摆位误差。结果:椎体肿瘤37例行114次扫描,只考虑误差大小时X轴、Y轴、Z轴方向误差分别为（2.69±2.46） mm、(5.37±4.57) mm、(4.02±3.5) mm。其中胸椎（2.02±2.07） mm、（4.80±4.59） mm、（4.00±3.92） mm,腰椎（3.35±2.65） mm、（5.83±4.54） mm、（4.03±3.08） mm。结论:腰椎患者与胸椎患者相比,摆位误差左右方向较大,在摆位中应加以注意,以减少治疗摆位误差。     

Deriving patient-specific planning target volume for partial bladder image guided radiation therapy

PurposeImage guided radiation therapy (IGRT) using bony anatomy for bladder cancer requires the use of large population-based planning target volume (PTV) margins to compensate for geometric uncertainties. This may result in a large volume of normal tissue being irradiated unnecessarily. Identification of the clinical target volume (CTV) is also a challenge during target delineation and treatment position verification. This study describes the use of lipiodol (Guerbet, US) and cone beam computed tomography (CBCT) in deriving patient-specific PTV (PS-PTV) for partial bladder IGRT.Methods and materialsTwelve patients underwent lipiodol injection into the bladder wall prior to radiation treatment. A PS-PTV was generated by the following: (1) Delineating partial bladder CTV (CTVpb) on 15 CBCTs; (2) registering the CBCTs with the planning CT image using lipiodol; (3) combining the 15 CTVpb to create an occupancy volume (OV); and (4) expanding the OV by 3 mm. Its efficacy in reducing irradiated volume and in providing coverage was assessed by comparing it with a 20-mm population-based PTV (popPTV) and using phase 2 CBCTs.ResultsThe median PS-PTV and popPTV (cm³) were 102 (range, 37-336) and 325 (range, 211-631), respectively. Median distance between the CTVpb and the PS-PTV edge (mm) were 6 superior, 6 right, 7 left, 7 anterior, 8 posterior, and 11 inferior. The absolute median reduction in the overlapping volume of rectum, small bowel, and large bowel were 0.3 cm³, 5.3 cm³, and 13.0 cm³, respectively. Despite large reductions in volume and margin compared with popPTV, PS-PTV achieved 100% target coverage.ConclusionsUsing lipiodol and CBCT to derive PS-PTV facilitated large reductions in the irradiated normal tissue volume without compromising target coverage.     

Triggered Imaging With Auto Beam Hold and Pre-/Posttreatment CBCT During Prostate SABR: Analysis of Time Efficiency,Target Coverage,and Normal Volume Changes

PurposeOur purpose was to investigate time efficiency and target coverage for prostate stereotactic ablative radiation therapy (SABR) using triggered imaging (TI) and auto beam hold.Methods and MaterialsA total of 20 patients were treated with volumetric modulated arc–based SABR. Treatment verification consisted of pre- and post-radiation therapy cone beam computed tomography (CBCT) with gold marker-based TI every 3 seconds. In case of ≥3 mm (deviation limit) displacement, the treatment was interrupted and imaging-based correction was performed. Beam interruptions, intrafractional shifts, and treatment times were recorded. Prostate, rectum, and bladder were delineated on each CBCT. Target coverage was evaluated by comparing the individual prostate delineations with 98% isodose contour volumes (% of the evaluated volumes exceeding the reference). Both inter- and intrafractional changes of bladder and rectal volumes were assessed.ResultsThe average overall treatment time (±standard deviation) was 18 ± 11 min, with a radiation delivery time of 6 ± 3 min if no intrafractional CBCT acquisitions were necessary (91% of fractions). On average, 1.2 beam interruptions per fraction were required with 0/1 correction in 71% of the fractions. The mean residual 3-dimensional shift was 1.6 mm, exceeding the deviation limit in 8%. In the case of intrafractional CBCT and/or ≥2 corrections the treatment time dramatically increased. The 98% isodose lines did not encompass the prostate in only 8/180 (4%) evaluations in 6 different patients, leading to a loss of D98 between 0.1%-6% as a worst case scenario. The bladder volumes showed significant increases during treatment (P < .01) while rectal volumes were stable.ConclusionsTime efficiency of TI + auto beam hold with 3 mm/3 sec threshold during prostate SABR is comparable with competitive techniques, resulting in minimal 3-dimensional residual errors with maintained target coverage. Technical developments are necessary to further reduce radiation delivery time. Use of CBCT allowed full control of rectal volumes, while bladder volumes showed significant increases over time.