头颈肿瘤立体定向分次照射靶区定位的误差分析

背景与目的:明确靶区定位的精确度是立体定向分次照射质量保证的基本要求。本文主要分析头颈肿瘤立体定向分次照射(fractionatedstereotacticradiotherapy,FSRT)中机械等中心、CT定位、治疗摆位以及CT图像误差等可能引起的靶区定位误差。方法:使用立体定向治疗计划系统、靶点模拟器、头部定位框架检查各个治疗阶段靶区定位的误差。设置任意5个参考点,使用靶点模拟器检查CT定位误差;选取7个不同机器臂架/治疗床角度,定期用胶片检验使用的PhilipsSL-18直线加速器等中心误差大小;用验证片检查治疗摆位误差;对自制模体行CT扫描,分析CT图像伪影可能引起的图像误差。结果:CT定位误差约为(1.5±0.4)mm;在检查的不同机器臂架/治疗床角度中机械等中心最大误差为(1.0±0.6)mm;患者摆位的距离误差为(1.0±0.3)mm;整个治疗过程中靶区定位误差约为(2.1±0.8)mm。结论:立体定向分次照射中需要综合考虑各个阶段中可能对治疗靶区定位产生的影响,误差分析结果可用来确定治疗的计划靶区。     

The accuracy of frameless stereotactic intracranial radiosurgery

Purpose

To determine the accuracy of frameless stereotactic radiosurgery using the BrainLAB ExacTrac system and robotic couch by measuring the individual contributions such as the accuracy of the imaging and couch correction system, the linkage between this system and the linac isocenter and the possible intrafraction motion of the patient in the frameless mask.

Materials and methods

An Alderson head phantom with hidden marker was randomly positioned 31 times. Automated 6D couch shifts were performed according to ExacTrac and the deviation with respect to the linac isocenter was measured using the hidden marker. ExacTrac-based set-up was performed for 46 patients undergoing hypofractionated stereotactic radiotherapy for 135 fractions, followed by verification X-rays. Forty-three of these patients received post-treatment X-ray verification for 79 fractions to determine the intrafraction motion.

Results

The hidden target test revealed a systematic error of 1.5 mm in one direction, which was corrected after replacement of the system calibration phantom. The accuracy of the ExacTrac positioning is approximately 0.3 mm in each direction, 1 standard deviation. The intrafraction motion was 0.35 ± 0.21 mm, maximum 1.15 mm.

Conclusion

Intrafraction motion in the BrainLAB frameless mask is very small. Users are strongly advised to perform an independent verification of the ExacTrac isocenter in order to avoid systematic deviations.     

Noninvasive patient fixation for extracranial stereotactic radiotherapy.

PURPOSE: To evaluate the setup accuracy that can be achieved with a novel noninvasive patient fixation technique based on a body cast attached to a recently developed stereotactic body frame during fractionated extracranial stereotactic radiotherapy. METHODS AND MATERIALS: Thirty-one CT studies (> or = 20 slices, thickness: 3 mm) from 5 patients who were immobilized in a body cast attached to a stereotactic body frame for treatment of paramedullary tumors in the thoracic or lumbar spine were evaluated with respect to setup accuracy. The immobilization device consisted of a custom-made wrap-around body cast that extended from the neck to the thighs and a separate head mask, both made from Scotchcast. Each CT study was performed immediately before or after every second or third actual treatment fraction without repositioning the patient between CT and treatment. The stereotactic localization system was mounted and the isocenter as initially located stereotactically was marked with fiducials for each CT study. Deviation of the treated isocenter as compared to the planned position was measured in all three dimensions. RESULTS: The immobilization device can be easily handled, attached to and removed from the stereotactic frame and thus enables treatment of multiple patients with the same stereotactic frame each day. Mean patient movements of 1.6 mm+/-1.2 mm (laterolateral [LL]), 1.4 mm+/-1.0 mm (anterior-posterior [AP]), 2.3 mm+/-1.3 mm (transversal vectorial error [VE]) and < slice thickness = 3 mm (craniocaudal [CC]) were recorded for the targets in the thoracic spine and 1.4 mm+/-1.0 mm (LL), 1.2 mm+/-0.7 mm (AP), 1.8 mm+/-1.2 mm (VE), and < 3 mm (CC) for the lumbar spine. The worst case deviation was 3.9 mm for the first patient with the target in the thoracic spine (in the LL direction). Combining those numbers (mean transversal VE for both locations and maximum CC error of 3 mm), the mean three-dimensional vectorial patient movement and thus the mean overall accuracy can be safely estimated to be < or = 3.6 mm. CONCLUSION: The presented combination of a body cast and head mask system in a rigid stereotactic body frame ensures reliable noninvasive patient fixation for fractionated extracranial stereotactic radiotherapy and may enable dose escalation for less radioresponsive tumors that are near the spinal cord or otherwise critically located while minimizing the risk of late sequelae.     

A dosimetric analysis of respiration-gated radiotherapy in patients with stage III lung cancer

Background

The purpose of the study was the clinical implementation of a kV cone beam CT (CBCT) for setup correction in radiotherapy.

Patients and methods

For evaluation of the setup correction workflow, six tumor patients (lung cancer, sacral chordoma, head-and-neck and paraspinal tumor, and two prostate cancer patients) were selected. All patients were treated with fractionated stereotactic radiotherapy, five of them with intensity modulated radiotherapy (IMRT). For patient fixation, a scotch cast body frame or a vacuum pillow, each in combination with a scotch cast head mask, were used. The imaging equipment, consisting of an x-ray tube and a flat panel imager (FPI), was attached to a Siemens linear accelerator according to the in-line approach, i.e. with the imaging beam mounted opposite to the treatment beam sharing the same isocenter. For dose delivery, the treatment beam has to traverse the FPI which is mounted in the accessory tray below the multi-leaf collimator. For each patient, a predefined number of imaging projections over a range of at least 200 degrees were acquired. The fast reconstruction of the 3D-CBCT dataset was done with an implementation of the Feldkamp-David-Kress (FDK) algorithm. For the registration of the treatment planning CT with the acquired CBCT, an automatic mutual information matcher and manual matching was used.

Results and discussion

Bony landmarks were easily detected and the table shifts for correction of setup deviations could be automatically calculated in all cases. The image quality was sufficient for a visual comparison of the desired target point with the isocenter visible on the CBCT. Soft tissue contrast was problematic for the prostate of an obese patient, but good in the lung tumor case. The detected maximum setup deviation was 3 mm for patients fixated with the body frame, and 6 mm for patients positioned in the vacuum pillow. Using an action level of 2 mm translational error, a target point correction was carried out in 4 cases. The additional workload of the described workflow compared to a normal treatment fraction led to an extra time of about 10–12 minutes, which can be further reduced by streamlining the different steps.

Conclusion

The cone beam CT attached to a LINAC allows the acquisition of a CT scan of the patient in treatment position directly before treatment. Its image quality is sufficient for determining target point correction vectors. With the presented workflow, a target point correction within a clinically reasonable time frame is possible. This increases the treatment precision, and potentially the complex patient fixation techniques will become dispensable.     

Évaluation par tomodensitométrie du repositionnement en radiothérapie stéréotaxique fractionnée cérébrale

PurposeTo evaluate the accuracy of patient repositioning in fractionated cerebral stereotactic radiotherapy using a Brain Lab? stereotactic cranial mask in conjunction with standard dental fixation.Patients and methodsFifty planning and checking CT scans were performed in 25 patients. The check CT scan was performed before or after one of the three sessions of treatment. Coregistration to the planning CT scan was used to assess alignment of the isocentre to the reference markers. The relative position of the PTV with regard to isocentre allowed us to determine its total displacement (3D vector).ResultsMean isocentre translations (± SD) taking into account direction were ?0.01 ± 0.7, ?0.2 ± 1.3 and 0.07 ± 0.5 mm in mediolateral, craniocaudal and anteroposterior directions respectively. Mean rotations (± SD) were ?0.02 ± 0.6, ?0.08 ± 0.3 and ?0.1 ± 0.3 degree in mediolateral, craniocaudal and anteroposterior axes respectively. Mean overall PTV displacement was 1.8 ± 1.5 mm. PTV displacement was smaller than 2 and 3 mm in 19/25 and 23/25 patients respectively.ConclusionThe accuracy of patient positioning using a stereotactic cranial mask system is similar to those reported in the literature and shows a satisfactory reproducibility with a standard dental fixation.     

放射治疗电子射野影像系统的系统摆位误差的评估(英文)

Objective:The aim of this work was to quantify the extent of set-up errors to conduct a quality assurance(QA)aspect of treatment delivery,verification of the treatment field’s position on different days using electronic portal.Methods:This study was carried out on 12 patients,treated for pelvis tumor;and total of 240 images obtained by electronic portal image device(EPID)were analyzed.The EPIs acquire using EPID attached to the Siemens linear accelerator.The anatomy matching software(Theraview)was used and displacement in two dimensions were noted for each treatment field to study patient setup errors.Results:The percentages of mean deviations less than 5 mm in X direction were 65%&92%,from 5–10 mm were 31%&19%and more than 10 mm were 11%&9%for A/P and lateral direction respectively.The percentages of mean deviations less than 5 mm in Y direction were 65%&63%,from 5–10 mm were 33%&28%and more than 10 mm were 22%&29%.The mean deviations in 2D-vector errors were≤5 mm in 47%and 46%,5–10 mm in 36%and 37%and>10 mm in37%and 37%of images in the A/P and lateral direction respectively.Conclusion:The results revealed that the ranges of set up errors are immobilization method to improve reproducibility.The observed variations were not within the limits..     

Reproducibility of patient setup by surface image registration system in conformal radiotherapy of prostate cancer

Background

In stereotactic body radiotherapy (SBRT) for lung tumors, reducing tumor movement is necessary. In this study, we evaluated changes in tumor movement and percutaneous oxygen saturation (SpO₂) levels, and preliminary clinical results of SBRT using the BodyFIX immobilization system.

Methods

Between 2004 and 2006, 53 consecutive patients were treated for 55 lesions; 42 were stage I non-small cell lung cancer (NSCLC), 10 were metastatic lung cancers, and 3 were local recurrences of NSCLC. Tumor movement was measured with fluoroscopy under breath holding, free breathing on a couch, and free breathing in the BodyFIX system. SpO₂ levels were measured with a finger pulseoximeter under each condition. The delivered dose was 44, 48 or 52 Gy, depending on tumor diameter, in 4 fractions over 10 or 11 days.

Results

By using the BodyFIX system, respiratory tumor movements were significantly reduced compared with the free-breathing condition in both craniocaudal and lateral directions, although the amplitude of reduction in the craniocaudal direction was 3 mm or more in only 27% of the patients. The average SpO₂ did not decrease by using the system. At 3 years, the local control rate was 80% for all lesions. Overall survival was 76%, cause-specific survival was 92%, and local progression-free survival was 76% at 3 years in primary NSCLC patients. Grade 2 radiation pneumonitis developed in 7 patients.

Conclusion

Respiratory tumor movement was modestly suppressed by the BodyFIX system, while the SpO₂ level did not decrease. It was considered a simple and effective method for SBRT of lung tumors. Preliminary results were encouraging.     

A clinical comparison of patient setup and intra-fraction motion using frame-based radiosurgery versus a frameless image-guided radiosurgery system for intracranial lesions

Background and purpose

A comparison of patient positioning and intra-fraction motion using invasive frame-based radiosurgery with a frameless X-ray image-guided system utilizing a thermoplastic mask for immobilization.

Materials and methods

Overall system accuracy was determined using 57 hidden-target tests. Positioning agreement between invasive frame-based setup and image-guided (IG) setup, and intra-fraction displacement, was evaluated for 102 frame-based SRS treatments. Pre and post-treatment imaging was also acquired for 7 patients (110 treatments) immobilized with an aquaplast mask receiving fractionated IG treatment.

Results

The hidden-target tests demonstrated a mean error magnitude of 0.7 mm (SD = 0.3 mm). For SRS treatments, mean deviation between frame-based and image-guided initial positioning was 1.0 mm (SD = 0.5 mm). Fusion failures were observed among 3 patients resulting in aberrant predicted shifts. The image-guidance system detected frame slippage in one case. The mean intra-fraction shift magnitude observed for the BRW frame was 0.4 mm (SD = 0.3 mm) compared to 0.7 mm (SD = 0.5 mm) for the fractionated patients with the mask system.

Conclusions

The overall system accuracy is similar to that reported for invasive frame-based SRS. The intra-fraction motion was larger with mask-immobilization, but remains within a range appropriate for stereotactic treatment. These results support clinical implementation of frameless radiosurgery using the Novalis Body Exac-Trac system.     

Progression of hearing loss after LINAC-based stereotactic radiotherapy for vestibular schwannoma is associated with cochlear dose,not with pre-treatment hearing level

Background

Although stereotactic radiotherapy (SRT) for vestibular schwannoma has demonstrated excellent local control rates, hearing deterioration is often reported after treatment. We therefore wished to assess the change in hearing loss after SRT and to determine which patient, tumor and treatment-related factors influence deterioration.

Methods

We retrospectively analyzed progression of hearing loss in patients with vestibular schwannoma who had received stereotactic radiosurgery (SRS) or fractionated stereotactic radiotherapy (FSRT) as a primary treatment between 2000 and 2014. SRS had been delivered as a single fraction of 12?Gy, and patients treated with FSRT had received 30 fractions of 1.8?Gy. To compare the effects of SRS and FSRT, we converted cochlear doses into EQD₂. Primary outcomes were loss of functional hearing, Gardner Robertson (GR) classes I and II, and loss of baseline hearing class. These events were used in Kaplan Meier plots and Cox regression. We also calculated the rate of change in Pure Tone Average (PTA) in dB per month elapsed after radiation—a measure we use in linear regression—to assess the associations between the rate of change in PTA and age, pre-treatment hearing level, tumor size, dose scheme, cochlear dose, and time elapsed after treatment (time-to-first-audiogram).

Results

The median follow-up was 36?months for 67 SRS patients and 63?months for 27 FSRT patients. Multivariate Cox regression and in linear regression both showed that the cochlear V90 was significantly associated with the progression of hearing loss. But although pre-treatment PTA correlated with rate of change in Cox regression, it did not correlate in linear regression. The time-to-first-audiogram was also significantly associated, indicating time dependency of the rate of change. None of the analysis showed a significant difference between dose schemes.

Conclusions

We found no significant difference between SRS and FSRT. As the deterioration in hearing after radiotherapy for vestibular schwannoma was associated with the cochlea V90, restricting the V90 may reduce progression of hearing loss. The association between loss of functional hearing and baseline PTA seems to be biased by the use of a categorized variable for hearing loss.

     

Safety and effectiveness of stereotactic body radiotherapy for a clinically diagnosed primary stage I lung cancer without pathological confirmation

Background

Pathological diagnosis fails in some pulmonary tumors, although they may be highly suspected to be primary lung cancer. We studied the outcome of stereotactic body radiotherapy for a clinically diagnosed primary stage I lung cancer without pathological confirmation.

Methods

The current study included 37 patients (39 lesions) treated with stereotactic body radiotherapy who were clinically diagnosed with primary stage I lung cancer between August 1998 and April 2009 at our hospital. Pulmonary tumors were highly suspected to be malignant from physical and imaging examinations. Biopsies were performed for 62 % of patients, although malignancy was not pathologically confirmed. In the other 38 % of patients, a biopsy was not feasible. Median age of the patients was 77 years. Median tumor diameter was 20 mm. A total median dose of 48 Gy was prescribed to the isocenter in four fractions. Median follow-up period was 39 months.

Results

The 3-year overall survival, local control, and regional-distant control were 74.2, 94.0, and 68.6 %, respectively. In patients with tumors ≤20 mm, overall survival and regional-distant control were significantly higher than in patients with tumors >20 mm (p ≤ 0.001), whereas no significant difference was observed regarding local control. No grade 3–5 adverse events possibly, probably, or definitely related to the treatment were observed.

Conclusions

Stereotactic body radiotherapy is safe and effective for a clinically diagnosed primary stage I lung cancer when pathological diagnosis is difficult even with repeat biopsies, or a biopsy is not feasible for reasons of the patient’s health condition or wishes.     

Treatment accuracy of fractionated stereotactic radiotherapy.

BACKGROUND AND PURPOSE: To assess the geometric accuracy of the delivery of fractionated stereotactic radiotherapy (FSRT) for brain tumours using the Gill-Thomas-Cosman (GTC) relocatable frame. Accuracy of treatment delivery was measured via portal images acquired with an amorphous silicon based electronic portal imager (EPI). Results were used to assess the existing verification process and to review the current margins used for the expansion of clinical target volume (CTV) to planning target volume (PTV). PATIENTS AND METHODS: Patients were immobilized in a GTC frame. Target volume definition was performed on localization CT and MRI scans and a CTV to PTV margin of 5mm (based on initial experience) was introduced in 3D. A Brown-Roberts-Wells (BRW) fiducial system was used for stereotactic coordinate definition. The existing verification process consisted of an intercomparison of the coordinates of the isocentres and anatomy between the localization and verification CT scans. Treatment was delivered with 6 MV photons using four fixed non-coplanar conformal fields using a multi-leaf collimator. Portal imaging verification consisted of the acquisition of orthogonal images centred through the treatment isocentre. Digitally reconstructed radiographs (DRRs) created from the CT localization scans were used as reference images. Semi-automated matching software was used to quantify set up deviations (displacements and rotations) between reference and portal images. RESULTS: One hundred and twenty six anterior and 123 lateral portal images were available for analysis for set up deviations. For displacements, the total errors in the cranial/caudal direction were shown to have the largest SD's of 1.2 mm, while systematic and random errors reached SD's of 1.0 and 0.7 mm, respectively, in the cranial/caudal direction. The corresponding data for rotational errors (the largest deviation was found in the sagittal plane) was 0.7 degrees SD (total error), 0.5 degrees (systematic) and 0.5 degrees (random). The total 3D displacement was 1.8 mm (mean), 0.8 mm (SD) with a range of 0.3-3.9 mm. CONCLUSIONS: Portal imaging has shown that the existing verification and treatment delivery techniques currently in use result in highly reproducible setups. Random and systematic errors in the treatment planning and delivery chain will always occur, but monitoring and minimising them is an essential component of quality control. Portal imaging provides fast and accurate facility for monitoring patients on treatment and the results of this study have shown that a reduction in CTV to PTV margin from 5 to 4 mm (resulting in a considerable increase in the volume of normal tissue sparing) could be made.     

Accuracy assessment methods of tissue marker clip placement after 11-gauge vacuum-assisted stereotactic breast biopsy: comparison of measurements using direct and conventional methods

Background

The objective of the study was to compare direct measurement with a conventional method for evaluation of clip placement in stereotactic vacuum-assisted breast biopsy (ST-VAB) and to evaluate the accuracy of clip placement using the direct method.

Methods

Accuracy of clip placement was assessed by measuring the distance from a residual calcification of a targeted calcification clustered to a clip on a mammogram after ST-VAB. Distances in the craniocaudal (CC) and mediolateral oblique (MLO) views were measured in 28 subjects with mammograms recorded twice or more after ST-VAB. The difference in the distance between the first and second measurements was defined as the reproducibility and was compared with that from a conventional method using a mask system with overlap of transparent film on the mammogram. The 3D clip-to-calcification distance was measured using the direct method in 71 subjects.

Results

The reproducibility of the direct method was higher than that of the conventional method in CC and MLO views (P = 0.002, P < 0.001). The median 3D clip-to-calcification distance was 2.8 mm, with an interquartile range of 2.0–4.8 mm and a range of 1.1–36.3 mm.

Conclusion

The direct method used in this study was more accurate than the conventional method, and gave a median 3D distance of 2.8 mm between the calcification and clip.

     

Cone-beam computed tomography in hypofractionated stereotactic radiotherapy for brain metastases

ABSTRACT: BACKGROUND: To assess interfraction translational and rotational setup errors, in patients treated with image-guided hypofractionated stereotactic radiotherapy, immobilized by a thermoplastic mask and a bite-block and positioned using stereotactic coordinates. METHODS: 37 patients with 47 brain metastases were treated with hypofractionated stererotactic radiotherapy. All patients were immobilized with a combination of a thermoplastic mask and a bite-block fixed to a stereotactic frame support. Daily cone-beam CT scans were acquired for every patient before the treatment session and were matched online with planning CT images, for 3D image registration. The mean value and standard deviation of all translational (X,Y,Z) and rotational errors (thetax, thetay, thetaz) were calculated for the matching results of bone matching algorithm. RESULTS: A total of 194 CBCT scans were analyzed. Mean +/- standard deviation of translational errors (X, Y, Z) were respectively 0.5 +/- 1.6 mm (range -5.7 and 5.9 mm) in X; 0.4 +/- 2.7 mm (range -8.2 and 12.1 mm) in Y; 0.4 +/- 1.9 mm (range -7.0 and 14 mm) in Z; median and 90th percentile were respectively within 0.5 mm and 2.4 mm in X, 0.3 mm and 3.2 mm in Y, 0.3 mm and 2.2 mm in Z. Mean +/- standard deviation of rotational errors (thetax, thetay, thetaz) were respectively 0.0 degrees +/- 1.3 degrees (thetax) (range -6.0 degrees and 3.1 degrees); -0.1 degrees +/- 1.1 degrees (thetay) (range -3.0 degrees and 2.4 degrees); -0.6 degrees +/- 1.4 degrees (thetaz) (range -5.0 degrees and 3.3 degrees). Median and 90th percentile of rotational errors were respectively within 0.1 degrees and 1.4 degrees (thetax), 0.0 degrees and 1.2 degrees (thetay), 0.0 degrees and 0.9 degrees (thetaz). Mean +/- SD of 3D vector was 3.1 +/- 2.1 mm (range 0.3 and 14.9 mm); median and 90th percentile of 3D vector was within 2.7 mm and 5.1 mm. CONCLUSIONS: Hypofractionated stereotactic radiotherapy have the significant limitation of uncertainty in interfraction repeatability of the patient setup; image-guided radiotherapy using cone-beam computed tomography improves the accuracy of the treatment delivery reducing setup uncertainty, giving the possibility of 3-dimensional anatomic informations in the treatment position.     

Bevacizumab and re-irradiation for recurrent high grade gliomas: does sequence matter?

Purpose/objectives

We report the outcomes of the largest cohort to date of patients receiving both bevacizumab (BEV) and fractionated stereotactic radiotherapy (FSRT) for progressive or recurrent high grade glioma (HGG). Furthermore, the sequence of these two treatment regimens was analyzed to determine an optimal treatment paradigm for recurrent HGG.

Materials/methods

After Institutional Review Board approval, patients with pathologically confirmed WHO grade III anaplastic astrocytoma (AA) or IV glioblastoma multiforme (GBM) glioma who subsequently underwent re-irradiation at recurrence with FSRT were retrospectively reviewed. Patients from this group who had received BEV were also identified. Survival from initial diagnosis, as well as from recurrence and re-irradiation, were analyzed as study endpoints. Date of recurrence was defined as the date of radiographic evidence of progressive/recurrent disease. Kaplan–Meier curves were generated utilizing a log-rank test with a p-value?≤?0.05 considered significant to compare treatment sequences in terms of survival outcomes.

Results

A total of 118 patients with recurrent/progressive HGG (GBM?=?87, AA?=?31) had received both BEV and FSRT. Patient characteristics were as follows: median KPS at recurrence was 80 (range 50–100); median age at recurrence was 57 years; median time to radiographic recurrence/progression was 10.8 months (mo) and 33.1% of patients had surgery for recurrence. The median time from the start of BEV to FSRT was 6.4 months and from FSRT to the start of BEV was 5.1 months. For the entire cohort, median overall survival (OS) was 26.7 months and median survival time (MST) from recurrence was 13.8 months (24.4 months and 11.9 months for GBM only). In patients that received BEV prior to FSRT (n?=?50), median OS and MST from recurrence were 25.2 and 13.3 months respectively. In patients receiving FSRT first (n?=?56), median OS and MST from recurrence were 28.8 months and 13.9 months, respectively. Sequencing of BEV and FSRT at recurrence was not significantly associated with OS (p?=?0.08) or median survival from recurrence (p?=?0.75).

Conclusions

The combination of FSRT and BEV for recurrent/progressive HGG provides promising results in terms of overall survival and survival from recurrence. Combining these treatment modalities appears to improve upon the historic outcomes of either treatment alone. The outcomes data from this study support the ongoing RTOG trial exploring the combination of BEV and FSRT for recurrent HGG.

     

Fibrolamellar Hepatocellular Carcinoma: a Case Report with Distinct Radiological Features

Introduction

We report a rare case of a 23-year-old male who presented with abdominal discomfort for 15 days. An ultrasound was performed which showed a hypoechoic, heterogenous mass in the left lobe of the liver and distended portal vein, followed by further investigation with computed tomography (CT), MRI, and MRA. Serum alpha-fetoprotein was not elevated and hepatitis B antigen was negative.

Methods

CT scan depicted a nodular mass in left liver lobe with occlusion of both the central part and the two main branches of intrahepatic portal vein.

Result

Biopsy of the liver mass led to a diagnosis of fibrolamellar hepatocellular carcinoma.

Conclusion

Fibrolamellar carcinoma is an uncommon variant of hepatocellular carcinoma. The diagnosis is suggested by radiographic studies and is confirmed by histological examination.     

Assessment of the accuracy of a conventional simulation for radiotherapy of head and skull base tumors

In this prospective study we investigated the absolute accuracy of the conventional simulation in head and skull base tumors. 41 isocenters in 40 consecutive patients with tumors of the head and skull base were included. In all cases a rigid stereotactic mask system was used for non-invasive fixation. The stereotactic ("calculated") coordinates of the isocenter were defined by the treatment planning computer. Each patient underwent a physical simulation using exclusively anatomical reference points to define the "preliminary" isocenter. The displacement between its coordinates and those of the stereotactic target point was recorded in X-, Y- and Z-direction with help of the targeting device, and the spatial error was calculated. Additionally, the patients were stratified by basal or calvarial tumor site to estimate the importance of the basal bone structures in the simulation accuracy. The influence of the learning effect on simulation accuracy was also determined. The results showed an accuracy of set-up at the linac within 1 mm in all three directions as calculated from orthogonal portal films. Mean shift of the isocenter coordinates obtained from physical simulation compared to the calculated stereotactic coordinates was 2.15 mm, 2.54 mm, and 2.69 mm for X-, Y-, and Z-direction, respectively. Mean spatial displacement amounted 5.06 mm, and the median was 4.50 mm. No significant difference could be noted between basal and calvarial location of the isocenter. A significant "learning effect" was observed with a decrease in spatial shift with increasing patient numbers. This effect was stronger in basal lesions, whereas calvarial lesions showed only a minor, insignificant effect. In conclusion, a physical simulation requires a safety margin of 5 mm in PTV definition in addition to other factors, e.g. organ movement.     

Objective assessment of reconstructed breast hardness using a durometer

Background

Whether a durometer was suitable for objectively measuring reconstructed breast hardness was evaluated.

Methods

Subjects were 81 women who underwent expander-implant reconstructions following breast cancer ablation. Capsular contracture was evaluated with Baker grading. Capsular thickness was measured with T1-weighted MRI at the upper areola area. The durometer was placed on the upper areola. Multiple logistic regression analysis was performed to compare variables.

Results

On Baker grading, 17 breasts were Baker grade I, 52 breasts were Baker grade II, 11 breasts were Baker grade III, and 1 breast was Baker grade IV. Mean capsular thickness on MRI was 1.1 (SD 0.4) mm with Baker grade I, 1.2 (SD 0.3) mm with Baker grade II, 1.4 (SD 0.4) mm with Baker grade III, and 1.9 mm with Baker grade IV. Mean durometer value was 0 with Baker grade I, 0.2 (SD 0.5) with Baker grade II, 2.0 (SD 1.7), with Baker grade III, and 8 with Baker grade IV. Baker grade IV was excluded from analysis because there was only one case. When Baker grade III was defined as positive for hardness, multiple logistic regression analysis showed that durometer value was associated with Baker grade III (p = 0.0005), but capsular thickness was not. On receiver operating characteristic curve analysis of the durometer value for Baker grade III, the optimal cutoff value was 0.5 (sensitivity 0.92, 1-specificity 0.17, area under the curve 0.92).

Conclusions

The durometer offers an objective index of hardness that might replace the subjective Baker grading. Further studies are needed to confirm the utility of this index.

     

Early intervention using high-precision radiotherapy preserved visual function for five consecutive patients with optic nerve sheath meningioma

Background

There has been a paradigm shift in the treatment for optic nerve sheath meningioma (ONSM) from surgery to fractionated stereotactic radiotherapy (FSRT) in other countries. However, FSRT has seldom been performed in Japan. The purpose of this retrospective study is to reconfirm the effectiveness of early intervention with precision radiotherapy for ONSM reported in our previous study.

Methods

Five consecutive patients with ONSM were retrospectively analyzed. All patients underwent intensity-modulated radiotherapy (IMRT) or FSRT. They received the early interventions between 1.5 and 7 months after deterioration of the disease. The median dose was 52.8 Gy (range 46.0–59.4 Gy) and the median number of fractions was 25 (range 22–33).

Results

All patients experienced reestablishment of vision at the median follow-up time of 36 months (range 18–54 months). Four of them noted early improvement of visual deficits during the treatment course (range 2–4 weeks) and the remaining patient improved 3 weeks after completion of IMRT. The median tumor reduction was 53% (range 39–75%). One patient with diabetes mellitus developed retinal bleeding as a result of radiation retinopathy 16 months after IMRT, although the doses were acceptable. The remaining 4 patients have no late toxicity at the follow-up time of 31–54 months.

Conclusions

A paradigm shift is necessary from surgery to early intervention using precision radiotherapy for the treatment of ONSM in Japan.

     

A correlative study of CT, MR and pathology in rabbit liver after embolization by a China - Formulated lipiodol emulsion

Objective

To explore the MR characteristics following lipiodol retention in rabbit liver and to evaluate the sensitivity of CT (CT value >400 HU) and MR in displaying the hepatic degeneration and necrosis following embolization.

Methods

Thirty-two rabbits were randomly divided into 3 groups. In the control group (n=8), 2 ml of normal saline was injected into the right branch of the portal vein. In the first experimental group(n=12), 4 ml of lipiodol emulsion was injected into the main portal vein. In the second experimental group (n=12), 2 ml of lipiodol emulsion was injected into the right branch of the portal vein. CT and MR images were obtained before and after surgery in each group. The histopathologic condition was determined for all liver tissue specimens.

Results

In the control group, CT and MR did not show any significant changes in the livers after surgery. After the operations in the experimental groups, the regional CT attenuation was 601 ±101 HU in the largest slice, which had no abnormal signals on T₁WI and T₂WI. In the first group, histologic examinations showed there were concentrated lipiodol droplets around the portal areas. In the second group, serious degeneration and necrosis in the right hepatic lobe occurred in 9 rabbits. T₁WI displayed homogenous or non-homogenous low signals and T₂WI mainly displayed a high signal. However, these pathologic changes did not appear on CT scanning due to high attenuation of the lipiodol.

Conclusion

There were no remarkable hepatic changes on MR in rabbits following good retention of the formulated lipiodol emulsion mixture of lipiodol and urografin(CT value > 400 HU). MR displayed serious degeneration and necrosis of the liver following embolization.     

Repositioning accuracy of a commercially available double-vacuum whole body immobilization system for stereotactic body radiation therapy

We evaluated the repositioning accuracy of a commercially available stereotactic whole body immobilization system (BodyFIX, Medical Intelligence, Schwabmuenchen, Germany) in 36 patients treated by hypofractionated stereotactic body radiation therapy. CT data were acquired for positional control of patient and tumor before each fraction of the treatment course. Those control CT datasets were compared with the original treatment planning CT simulation and analyzed with respect to positional misalignment of bony patient anatomy, and the respective position of the treated small lung or liver lesions. We assessed the stereotactic coordinates of distinct bony anatomical landmarks in the original CT and each control dataset. In addition, the target isocenter was recorded in the planning CT simulation dataset. An iterative optimization algorithm was implemented, utilizing a root mean square scoring function to determine the best-fit orientation of subsequent sets of anatomical landmark measurements relative to the original treatment planning CT data set. This allowed for the calculation of the x, y and z-components of translation of the patient's body and the target's center-of-mass for each control CT study, as well as rotation about the principal room axes in the respective CT data sets. In addition to absolute patient/target translation, the total magnitude vector of patient and target misalignment was calculated. A clinical assessment determined whether or not the assigned planning target volume safety margins would have provided the desired target coverage. To this end, each control CT study was co-registered with the original treatment planning study using immobilization system related fiducial markers, and the computed isodose calculation was superimposed. In 109 control setup CT scans available for comparison with their respective treatment planning CT simulation study (2-5 per patient, median 3), anatomical landmark analysis revealed a mean bony landmark translation of -0.4 +/- 3.9 (mean +/- SD), -0.1 +/- 1.6 and 0.3 +/- 3.6 mm in x, y and z-directions, respectively. Bony landmark setup deviations along one or more principal axis larger than 5 mm were observed in 32 control CT studies (29.4%). Body rotations about the x-, y- and z-axis were 0.9 +/- 0.7, 0.8 +/- 0.7 and 1.8 +/- 1.6 degrees, respectively. Assuming a rigid body relationship of target and bony anatomy, the mean computed absolute target translation was 2.9 +/- 3.3, 2.3 +/- 2.5 and 3.2 +/- 2.7 mm in x, y and z-directions, respectively. The median and mean magnitude vector of target isocenter displacement was computed to be 4.9 mm, and 5.7 +/- 3.7 mm. Clinical assessment of PTV/target volume coverage revealed 72 (66.1%), 23 (21.1%), and 14 (12.8%), of excellent (100% isodose coverage), good (>90% isodose coverage), and poor GTV/isodose alignment quality (less than 90% isodose coverage to some aspect of the GTV), respectively. Loss of target volume dose coverage was correlated with translations >5 mm along one or more axes (p<0.0001), rotations >3 degrees about the z-axis (p=0.0007) and body mass index >30 (p<0.0001). The analyzed BodyFIX whole body immobilization system performed favorably compared with other stereotactic body immobilization systems for which peer-reviewed repositioning data exist. While the measured variability in patient and target setup provided clinically acceptable setup accuracy in the vast majority of cases, larger setup deviations were occasional observed. Such deviations constitute a potential for partial target underdosing warranting, in our opinion, a pre-delivery positional assessment procedure (e.g., pre-treatment control CT scan).