A quality assurance phantom for three-dimensional radiation treatment planning.

PURPOSE: Three-dimensional (3D) radiation treatment planning is facilitated through the use of computerized radiation treatment planning systems (RTPSs) and CT simulators (CT-sims). Quality assurance (QA) of these systems is necessary for ensuring that they fulfill their potential. However, comprehensive tools for the systematic QA of these systems have not been developed. We present a phantom that facilitates the evaluation of a large number of nondosimetric functions. These include CT image acquisition and transfer, graphical displays of 3D radiation beams, multiplanar CT image reconstructions, digitally reconstructed radiographs, the representation and manipulation of contoured patient anatomy, dose volume histograms, and the conversion of CT numbers to relative electron densities. METHODS AND MATERIALS: A phantom was constructed which contains materials and geometries that are appropriate for the routine QA of the features described above. The anatomy of the phantom is used as a standard against which the performance of the 3D-RTPS or CT-sim is evaluated. The phantom was used to evaluate three different 3D-RTPSs and a CT-sim at four institutions. RESULTS: Using this phantom, clinically significant errors and limitations in commercially available 3D treatment planning software were discovered. No errors were discovered in the beam display or image reconstructions in the systems examined. Problems were found in the anatomy display, automatic tools, and the CT number to relative electron density conversion data used in some of the systems. CONCLUSION: This phantom is a unique tool designed explicitly for the QA of 3D treatment planning software. Errors and limitations discovered through its use indicate that the QA of commercial treatment planning software is necessary, and that this phantom is an effective device for this task.     

3D volumetric analysis for planning breast reconstructive surgery

Breast reconstruction plays an integral role in the holistic management of breast cancer, with assessment of breast volume, shape, and projection vital in planning breast reconstruction surgery. Current practice includes two-dimensional (2D) photography and visual estimation in selecting ideal volume and shape of breast implants or soft-tissue flaps. Other objective quantitative means of calculating breast volume have been reported, such as direct anthropomorphic measurements or three-dimensional (3D) photography, but none have proven reliably accurate. We describe a novel approach to volumetric analysis of the breast, through the creation of a haptic, tactile model, or 3D print of scan data. This approach comprises use of a single computed tomography (CT) or magnetic resonance imaging (MRI) scan for volumetric analysis, which we use to compare to simpler estimation techniques, create software-generated 3D reconstructions, calculate, and visualize volume differences, and produce biomodels of the breasts using a 3D printer for tactile appreciation of volume differential. Using the technique described, parenchymal volume was assessed and calculated using CT data. A case report was utilized in a pictorial account of the technique, in which a volume difference of 116 cm³ was calculated, aiding reconstructive planning. Preoperative planning, including volumetric analysis can be used as a tool to aid esthetic outcomes and attempt to reduce operative times in post-mastectomy breast reconstruction surgery. The combination of accurate volume calculations and the production of 3D-printed haptic models for tactile feedback and operative guidance are evolving techniques in volumetric analysis and preoperative planning in breast reconstruction.     

Unmasking a Privacy Concern: Potential Identification of Patients in an Immobilization Mask from 3-Dimensional Reconstructions of Simulation Computed Tomography

Previous studies have demonstrated that patients can be identified from 3-dimensional (3D) reconstructions of computed tomography (CT) or magnetic resonance imaging data of the brain or head and neck. This presents a privacy and security concern for scan data released to public data sets. It is unknown whether thermoplastic immobilization masks used for treatment planning in radiation therapy are sufficient to prevent facial recognition. Our study sought to evaluate whether patients with an immobilization mask could be identified on 3D reconstructions of scan data. Our study reconstructed 3D images from simulation CT (SIM-CT) scans of 35 patients and compared these to original patient photographs to test if the thermoplastic mask obfuscated facial features. Blind review from 4 facial recognition algorithms and a human (radiation oncologist) was evaluated for the ability to match 3D reconstructions of patients scans to patient images. The matching procedure was repeated against an expanded testing data set of the 35 patient photographs plus 13,233 facial photographs from the “Labeled Faces in the Wild” data set (13,268 photographs in total). Facial recognition algorithms were able to match a maximum of 83% (range, 60%-83%) of patients to the corresponding images. Radiation Oncologist blinded review correctly matched 80% of patients to the corresponding images. Ethnicity and facial hair were the most common reasons for patient mismatch. In the expanded testing data set, algorithms were also able to match a maximum of 83% (range, 57%-83%) of patients. The majority of patients were able to be identified through computer algorithm or human review even under a SIM-CT mask. These results suggest there is a potential privacy and security concern when SIM-CT data are released to publicly available data sets.     

容积调强弧形治疗冠矢状面剂量验证的初步探讨

目的 初步探讨容积调强弧形治疗(VMAT)在冠状面和矢状面的剂量验证意义。方法 选取 12例癌症患者的VMAT计划,在多插孔圆柱形体模内插入2个0.125 cm³的电离室探头进行点剂量测量。采用平面二维矩阵电离室及其组合体模,分别在冠状面和矢状面摆位方式下进行γ通过率的剂量验证。结果 在高剂量区域(>最大剂量的80%)和低剂量区域(≤最大剂量的80%)内,点剂量测量与计算结果平均误差分别为1.5%和1.7%。在冠状面和矢状面下二维电离室矩阵中心探头测量的点剂量与计算结果的平均差异为1.7%和1.8%。采用2%/2 mm、3%/3 mm标准的平均通过率分别为93.7%、97.2%。 结论 冠状面和矢状面VMAT剂量验证为临床VMAT计划提供了有意义的数据。     

Three-Dimensional OctreoScan111 Spect of Abdominal Manifestation of Neuroendocrine Tumours

In the present study we have investigated the three-dimensional (3D) reconstruction of Octreo-Scan111 SPECT (single photon emission tomography) images in 20 patients with neuroendocrine tumours. All patients had at least 2 tumour lesions as assessed from computerized tomography (CT) and SPECT. The 3D rendering was performed using a software, which produces images by implementing direct rendering from voxels without an intermediate surface data structure. The software has options for a free choice of thresholding and possibilities of clipping in coronal, transversal and sagittal planes. The results obtained showed that 3D reconstruction with volume rendering (3Dvr) gave a superior topographical localization of tumour uptakes when compared with SPECT. The 3Dvr technique was also combined with transversal clipping in rendered volumes (3Dvr + c). The major advantage with the 3Dvr + c technique was found to be an improved visualization of anatomical references as well as improved diagnostic information in a particular, selected, transversal slice, thus facilitating the identification and comparison of individual tumour lesions.     

High resolution spiral computed tomography of the pancreas

Computed tomography (CT) is a very useful tool in the assessment of pancreatic disease. Searching for subtle signs, as in chronic pancreatitis or staging of adenocarcinoma, high spatial and contrast resolution is needed. The high resolution computed tomography (HRCT) technique for pancreatic scans, and its evolution from dynamic CT to multislice spiral CT, is described. 2D and 3D dimensional reconstructions are depicted and their role in diagnosis is focused. Together with spatial resolution, contrast enhancement protocols are discussed, aimed to achieve optimal contrast between the lesion and normal parenchyma.     

The Impact of 3D Digital Reconstruction on the Surgical Planning of Partial Nephrectomy: A Case-control Study. Still Time for a Novel Surgical Trend?

IntroductionThe purpose of this study was to evaluate the impact of 3-dimensional (3D) digital reconstructions of renal models on the arterial clamping approach during partial nephrectomy (PN).Patients and MethodsFifty-seven patients with T1 renal mass, referred for PN, were prospectively enrolled in 2 groups: Group 1 (n = 32) with revision of both 2-dimensional (2D) computed tomography (CT) imaging and 3D virtual model before surgery; Group 2 (n = 25) with revision of 2D CT imaging. Segmentation of the 3D models from preoperative high-quality CT scan was achieved using D2P software. In a sub-analysis of patients treated with PN with the on-clamp approach (n = 36), the effective intraoperative level of arterial clamping was compared with the preoperative planning.ResultsIn the sub-group of patients referred to PN with the on-clamp approach, the intraoperative selective clamping was performed in 12 (57.1%) patients of Group 1 and in 2 (13.3%) cases of Group 2 (P = .01). The intraoperative management of the renal pedicle was done as preoperatively planned in 61.9% of patients in Group 1 and in 86.6% of cases in Group 2 (P = .1).ConclusionThe 3D-guided plan of PN allows to perform selective clamping in higher proportion of patients compared with the standard 2D-guided approach without increasing intraoperative and postoperative complications.     

二维治疗计划系统中的准三维剂量分布的估算与评价

目的：介绍一种在二维放射治疗计划系统中作准三维剂量分布的估算与评价的方法。方法：用上颌窦癌病例具体说明其作法。照射患者体内剂量分布的计算不但在射野中心的横断面进行，而且还在射时取中心的知状面、冠状面以及任意关注的横断面上同时进行，以得出感兴趣区域的剂量值。结果：该方法应用在上凳窦癌能清楚地了解眼眶内角、筛、蝶窦、对侧眼球和上凳窦以及脑辔受量。及时间高速计划减少复发的可能性，减少正常组织损伤。结论：     

前路减压n—HA／PA66支撑体植骨融合内固定治疗胸腰椎爆裂骨折的中期疗效

【摘要】目的观察前路减压纳米羟基磷灰石／聚酰胺66（n—HA／PA66）支撑体治疗胸腰椎爆裂骨折的中期疗效。方法回顾性分析我科2008年1月至2009年11月行前路减压、n—HA／PA66支撑体植骨融合内固定术治疗的46例胸腰段爆裂骨折患者。男33例,女13例,平均年龄54．5岁。收集患者术前及术后胸腰椎正侧位X线片、三维CT等影像学资料以及使用Frankel分级标准评价神经功能恢复情况等临床资料;通过侧位x线片测量融合节段高度及融合节段后凸角,通过CT三维重建评价植骨融合情况。结果本组病例随访平均50（42～64）个月,至末次随访植骨融合率为97．8％。术前、术后1周、术后6个月及末次随访的平均伤椎上下椎间高度分别为94．3mm、108．0mm、106．9mm、106．2mm;平均后凸角分别为18．2°、5．7°、6．0°、6．3°。患者术后1周的融合节段高度及后凸角均较术前显著改善（P〈0．001）;术后1周、6个月及末次随访的融合节段高度及后凸角比较差异无统计学意义fP〉0．05）,至末次随访时支撑体下沉平均为1．7mm。患者神经功能术前：A级3例、B级6例、C级16例、D级19例、E级2例;至末次随访：A级1例、B级2例、c级3例、D级14例、E级26例,末次随访时Frankel分级较术前有不同程度的改善。结论n—HA／PA66支撑植骨内固定能有效恢复及维持融合节段生理高度及弧度、促进植骨融合、方便术后手术节段的影像学观察,是一种较为理想的胸腰段植骨材料。使用前路减压、n—HA／PA66支撑体植骨融合内固定术治疗胸腰椎爆裂骨折的中期临床效果满意。     

Computed tomography colonography (virtual colonoscopy): Review

Computed tomography examination of the colon performed after bowel cleansing and distension of the lumen with gas goes by several different names—CT colonography (CTC) and CT colography perhaps being the most common. Strictly, the term ‘virtual colonoscopy’ (VC), should be reserved for the process of examining 3‐D, simulated endoluminal images with a capability to navigate through the bowel using appropriate software. Computed tomography colonography appears to be the name that has gained favour among radiologists, although it is suspected that ‘virtual colonoscopy’ will persist as a generic term due to its attractive ‘high‐tech’ connotations for non‐radiological medical and lay persons. Whatever the name, the technique has been made possible through the advent of fast helical CT scanners which allow acquisition of a volume of data, and of proprietary software which enables multiplanar reformatting and 3‐D endoluminal reconstructions. It is evident that if CTC/VC can be shown to be acceptable to patients, safe, affordable and accurate, it has enormous potential as a diagnostic and screening tool for colorectal neoplasia.     

MRI在侵袭性垂体腺瘤术前评估中的价值及临床意义

目的探讨MRI在侵袭性垂体腺瘤术前评估中的价值及临床意义。方法回顾性分析经手术病理证实的侵袭性垂体腺瘤36例,所有病例均接受3．0TMRIT1wI冠状位、矢状位,T2WI冠状位平扫及T1WI冠状位、矢状位和横轴位增强扫描。结果肿瘤以等T1、等或稍长他信号为主,增强扫描后均匀或不均匀强化。肿瘤向周围组织侵犯表现为颈动脉包绕,海绵窦受累;鞍底下陷,部分肿瘤突人蝶窦;突破鞍隔等。MRI示海绵窦4级受侵的有24侧,3级受侵的有27侧,术中均证实海绵窦受侵犯,颈内动脉部分或完全受包绕。结论MRI可在术前正确评估垂体腺瘤的侵袭性及侵袭范围,对手术方式以及术后治疗方案的选择具有重要的临床意义。     

Limitation of conventional two dimensional radiation therapy planning in nasopharyngeal carcinoma.

PURPOSE: To assess the adequacy of coverage of gross tumor volume (GTV) with traditional two dimensional (2D) radiation therapy (RT) planning in patients with nasopharyngeal cancer (NPC). MATERIALS AND METHODS: The study comprised 94 of 179 patients treated with definitive RT between 1993 and 1997. The inclusion requirement was the availability of a digitally archived pretreatment magnetic resonance imaging. The digital images were used to record the precise location of the GTV in the sagittal plane. As a separate procedure, sagittal dose distributions for each treatment phase were created by digitizing the simulation field parameters into treatment planning software without knowledge of the GTV. The location of the GTV and dose distribution in the sagittal plane were superimposed on each other and GTV coverage by the 50, 90 and 95% isodose lines determined for each phase of treatment. RESULTS: The 1997 tumour node metastasis (TNM) stage distribution was: 7 (8%) stage I, 16 (16%) stage II, 30 (32%) stage III and 41 (44%) stage IV. Median follow-up was 4.4 years. Median primary dose was 66 Gy. The actuarial 5-year overall survival, disease free survival and local relapse free rates were 88, 54 and 66%, respectively. The GTV was covered by the 50, 90 and 95% isodose lines for all phases of the multiphase plan in only 53, 20 and 9% of patients, respectively. The GTV was more likely to be undercovered in the latter phases of the plan particularly in those patients with advanced T category. CONCLUSION: 2D RT planning has significant limitations in achieving adequate GTV coverage in NPC. We strongly recommend 3D planning using either conformal techniques of dose delivery or intensity modulated radiation therapy for the treatment of these patients.     

不同位置子宫颈癌三维与二维近距离放疗剂量学研究和最适治疗人群探讨

目的 通过对CT引导的宫颈癌三维与二维近距离放疗计划的剂量学比较,探讨不同位置子宫对危及器官剂量分布和靶区适形度的影响以及二维近距离放疗治疗宫颈癌的最适人群。方法 纳入我科30例宫颈癌患者的72 次三维近距离放疗计划,并重新设计二维计划,测量子宫位置前后、左右偏离角度。分别按照宫体前后偏离角度(T)及HRCTV体积(VHRCTV)将数据分为A、B、C、D及Ⅰ、Ⅱ、Ⅲ、Ⅳ组,以探寻二维计划最适子宫位置和HRCTV体积范围。统计采用配对t检验差异。结果 宫体前后偏离角度与两种计划的CI值及HRCTV D90无相关性(P值为0.077~0.633),与两种计划中膀胱D2 cm³呈正相关(P值为0.001~0.030),直肠D2 cm³呈负相关(P值为0.011~0.016)。B组(|T|≤10°)及Ⅲ组(VHRCTV为86~96 cm³)中两种计划危及器官参数及CI 值均相近(P值为0.040~0.463);而其他组均有不同程度上的差异(P值为0.000~0.940)。结论 子宫前后位置虽然不影响靶区适形度,但会干扰周围危及器官剂量分布,而当子宫位置接近平位(前后偏离角度≤10°)、靶区体积适当(VHRCTV为86~96 cm³)时两种计划的剂量学相近,此时最适采用二维近距离放疗。     

The Value of the Lateral Cervical Myelogram in the Evaluation of Cervical Spondylosis

The sagittal diameters of the lateral cervical myelograms of twenty-seven patients with moderate to severe clinical cervical spondylosis were determined. These measurements were compared with those in an unselected group of asymptomatic patients of approximately the same average age. The results showed a definite decreate in the width of the cervical canal in the spondylotic patients. This discrepancy occurred at all levels, but was especially marked at the C4/C5 and C5/C6 intervertebral spaces. It is suggested that initial narrowing of the cervical canal may be developmental in origin. The importance of the sagittal diameter as a guide to management and prognosis is stressed.     

Virtual bronchoscopy: Our early experience

Virtual bronchoscopy is one of the many new radiological scanning techniques that have been recently introduced. Virtual endoscopy, according to Ahlquist (Ahlquist and Johnson CD, Gastroenterology, 112, 1997, 2150) is a technique for visualizing interior cavities using computer graphic techniques. Virtual bronchoscopy generates 3D reconstructions of the human airway from high-resolution CT data sets of the chest and performs a simulated bronchoscopy. This method uses perspective surface or volume rendering to produce endoscope-like visualizations of the airway. Our early experience with this new investigative modality in cases of laryngeal and subglottic stenosis and intratracheal tumors is discussed.     

Measurement of prostate rotation during insertion of needles for brachytherapy.

BACKGROUND AND PURPOSE: The purpose of this study is to investigate whether prostate rotation due to needle insertion for prostate brachytherapy is predictable and if so, to quantify this rotation, and to see whether locking needles reduce the magnitude of prostate rotation. PATIENTS AND METHODS: The measurements are done at the beginning of the procedure for brachytherapy with a Foley catheter in situ. After a needle is inserted into the prostate, a 3D ultrasound scan is made. Then the seeds are delivered using RAPID Strands (Oncura), and the needle is withdrawn. A second 3D scan is made. The needle and seed positions are determined in these scans. To determine the rotation of the prostate, the angle between the needle and the seed trajectory is calculated. RESULTS: The prostate rotations have been measured in 16 patients, eight without the use of locking needles and eight with locking needles. In total 62 needles were inserted. The maximum rotation was 13.8 degrees and occurred in the coronal plane when no locking needles were used with a significant correlation (P<0.01, R=0.637) between the place of insertion and rotation. It was shown that the method (with or without locking needles) had a significant (P<0.001) influence on the rotation in the coronal plane. Rotations in the sagittal plane ranged from -8.5 degrees to +10.2 degrees without correlation with the insertion point of the needle or the use of locking needles. CONCLUSIONS: This study showed that prostate rotation during needle insertion for prostate brachytherapy is relatively large and unpredictable. Locking needles reduce prostate rotation in the coronal plane, but not in the sagittal plane. Minimising this rotation is necessary for accurate seed delivery, especially when a robotic implantation technique is used.     

Comparison of conventional and conformational dosimetry in radiotherapy of cerebral neoplasms]

PURPOSE: We prospectively compared a conventional treatment planning (PT2D) and 3-dimensional conformal treatment planning (PT3D) for radiotherapy of cerebral tumours. PATIENTS AND METHODS: Patients treated between 1/10/98 and 1/4/99 by irradiation for cerebral tumours were analysed. For each case, we planned PT2D using conventional orthogonal x-ray films, and afterward, PT3D using CT scan. Gross tumor volume, planning target volume and normal tissue volumes were defined. Dose was prescribed according to report 50 of the International Commission on Radiation Units and Measurements (ICRU). We compared surfaces of sagittal view targets defined on PT2D and PT3D and called them S2D and S3D, respectively. Irradiated volumes by 90% isodoses (VE-90%) and normal tissue volumes irradiated by 20, 50, 90% isodoses were calculated and compared using Student's paired t-test. RESULTS: There was a concordance of 84% of target surfaces defined on PT2D and PT3D. Percentages of target surface under- or-over defined by PT2D were 16 and 13% respectively. VE-90% was decreased by 15% (p = 0.07) with PT3D. Normal brain volume irradiated by 90% isodose was decreased by 27% with PT3D (p = 0.04). CONCLUSION: For radiotherapy of cerebral tumors using only coplanar beams, PT3D leads to a reduction of normal brain tissue irradiated. We recommend PT3D for radiotherapy of cerebral tumors, particularly for low-grade or benign tumors (meningiomas, neuromas, etc.).     

A new method using MRI to delineate areas of head and neck cancer targeted by intra-arterial infusion via a superficial temporal artery

To determine whether anticancer drugs delivered via arterial infusion can permeate entire tumors using a new MRI flow check method. We infused 20 ml of contrast medium (2 ml of Gd-GDPA plus 18 ml of normal saline) over a period of 10 min using a continuous injection pump, then immediately performed MRI using a 1.5 T unit. Images were obtained in 5-mm-thick continuous sections in two or three planes (axial, coronal, and sagittal) depending on the extent of the tumor, and enhanced fast gradient echo 3 D (EFGRE3D) images with a special inversion at lipids were photographed using a neurovascular array coil. The new MRI flow check method delineated an area of tongue cancer perfused with drugs more accurately than conventional methods.The MRI flow check method provides accurate information about areas of arterial infusion.     

Three-dimensional movement of a liver tumor detected by high-speed magnetic resonance imaging

Objective: Three-dimensional (3D) movement of a spherical liver tumor during respiration was investigated with magnetic resonance imaging (MRI) using a high-speed sequence.

Methods: A marker was placed on the surface of the patient as a reference of distance. Repetition time (TR) was 7.7 ms, echo time (TE) was 4.2 ms, flip angle was 20°, section thickness was 8 mm, and a 256×128 matrix was used. The acquisition time was 1.0 s followed by an interval of 0.5 s. The 20 tumor contours extracted during 30 s were superimposed on sagittal and coronal MR images.

Results: The maximum value of tumor edge location was 3.9 cm in the cranio–caudal direction, 2.3 cm in the ventro–dorsal direction, and 3.1 cm in the lateral direction. The mean length of tumor displacement observed was 2.1 cm in the cranio–caudal direction, 0.8 cm in the ventro–dorsal and 0.9 cm in the left–right direction, respectively. The locus of the center of the tumor contour in the sagittal cross section was inclined at 23° and in the coronal cross section was inclined at 18° to the cranio–caudal axis of body.

Conclusion: In conclusion, 3D movement of a spherical liver tumor was detected using rapid MRI sequential examinations. Magnetic resonance imaging has a potential to improve the accuracy of the planning target volume of a liver tumor.     

On-board patient positioning for head-and-neck IMRT: comparing digital tomosynthesis to kilovoltage radiography and cone-beam computed tomography

PURPOSE: High-precision intensity-modulated radiotherapy demands high patient positioning accuracy. On-board digital tomosynthesis (DTS) provides three-dimensional (3D) image guidance for daily positioning with a lower imaging dose, faster acquisition, and more geometric flexibility than 3D cone-beam computed tomography (CBCT). This clinical study evaluated DTS as a daily imaging technique for patient positioning and compared the results with 3D CBCT and two-dimensional (2D) radiography. METHODS AND MATERIALS: Head and neck cancer patients undergoing intensity-modulated radiotherapy were studied. For each session, the patient was positioned using laser marks. On-board imaging data sets, including 2D kilovoltage radiographs, DTS, and CBCT, were obtained to measure the daily patient positioning variations. The mean and standard deviations of the positioning variations in the translational and rotational directions were calculated. The positioning differences among 2D radiography, DTS, and CBCT were analyzed. RESULTS: Image data sets were collected from 65 treatment fractions for 10 patients. The systematic patient positioning variation was <0.10 cm and 1.0 degrees one dimensionally. The random variations were 0.27-0.34 cm in the translational and 0.93 degrees -1.99 degrees in the rotational direction. The mean vector isocenter variation was 0.48 cm. DTS with 40 degrees and 20 degrees scan angles in the coronal or sagittal directions yielded the same results for patient positioning. DTS performance was comparable to that of CBCT, with positioning differences of <0.1 cm and 0.5 degrees . The positioning difference between 2D radiography and DTS was approximately 0.1 cm and 0.2 cm in the vertical/longitudinal and lateral directions. CONCLUSION: Our results have demonstrated that DTS is a comparable 3D imaging technique to CBCT for daily patient positioning of head-and-neck patients as determined by manual registration of bony anatomy.