Commissioning and Validation of CT Number to SPR Calibration in Carbon Ion Therapy Facility

Purpose

We performed computed tomography (CT)-stopping power ratio (SPR) calibration in a carbon-ion therapy facility and evaluated SPR estimation accuracy.

Materials and Methods

A polybinary tissue model method was used for the calibration of CT numbers and SPR. As a verification by dose calculation, we created a virtual phantom to which the CT-SPR calibration table was applied. Then, SPR was calculated from the change in the range of the treatment planning beam when changing to 19 different CT numbers, and the accuracy of the treatment planning system (TPS) calculation of SPR values from the CT-SPR calibration table was validated. As a verification by measurement, 5 materials (water, milk, olive oil, ethanol, 40% K2HPO4) were placed in a container, and the SPR was obtained by measurement from the change in the range of the beam that passed through the materials.

Results

The results of the dose calculations of the TPS showed that the results agreed within 1% for the lower CT numbers up to 1000 HU, but there was a difference of 3.0% in the higher CT number volume. The difference between the SPR calculated by TPS and the SPR caused by the difference in the energy of the incident particles agreed within 0.51%. The accuracy of SPR estimation was measured, and the error was within 2% for all materials tested.

Conclusion

These results indicate that the SPR estimation errors are within the range of errors that can be expected in particle therapy. From commissioning and verification results, the CT-SPR calibration table obtained during this commissioning process is clinically applicable.

A robust treatment planning approach for chest motion in postmastectomy chest wall intensity modulated radiation therapy

PURPOSE

Chest wall postmastectomy radiation therapy (PMRT) should consider the effects of chest wall respiratory motion. The purpose of this study is to evaluate the effectiveness of robustness planning intensity modulated radiation therapy (IMRT) for respiratory movement, considering respiratory motion as a setup error.

MATERIAL AND METHODS

This study analyzed 20 patients who underwent PMRT (10 left and 10 right chest walls). The following three treatment plans were created for each case and compared. The treatment plans are a planning target volume (PTV) plan (PP) that covers the PTV within the body contour with the prescribed dose, a virtual bolus plan (VP) that sets a virtual bolus in contact with the body surface and prescribing the dose that includes the PTV outside the body contour, and a robust plan (RP) that considers respiratory movement as a setup uncertainty and performs robust optimization. The isocenter was shifted to reproduce the chest wall motion pattern and the doses were recalculated for comparison for each treatment plan.

RESULT

No significant difference was found between the PP and the RP in terms of the tumor dose in the treatment plan. In contrast, VP had 3.5% higher PTV Dmax and 5.5% lower PTV V95% than RP (p < 0.001). The RP demonstrated significantly higher lung V20Gy and Dmean by 1.4% and 0.4 Gy, respectively, than the PP. The RP showed smaller changes in dose distribution affected by chest wall motion and significantly higher tumor dose coverage than the PP and VP.

CONCLUSION

We revealed that the RP demonstrated comparable tumor doses to the PP in treatment planning and was robust for respiratory motion compared to both the PP and the VP. However, the organ at risk dose in the RP was slightly higher; therefore, its clinical use should be carefully considered.

Error on the stopping power ratio of ERKODENT's mouthpiece for head and neck carbon ion radiotherapy treatment

The errors on the stopping power ratio (SPR) of mouthpiece samples from ERKODENT were evaluated. Erkoflex and Erkoloc-pro from ERKODENT and samples that combined Erkoflex and Erkoloc-pro were computed tomography (CT)-scanned using head and neck (HN) protocol at the East Japan Heavy Ion Center (EJHIC), and the values were averaged to obtain the CT number. The integral depth dose of the Bragg curve with and without these samples was measured for 292.1, 180.9, and 118.8 MeV/u of the carbon-ion pencil beam using an ionization chamber with concentric electrodes at the horizontal port of the EJHIC. The average value of the water equivalent length (WEL) of each sample was obtained from the difference between the range of the Bragg curve and the thickness of the sample. To calculate the difference between the theoretical and measured values, the theoretical CT number and SPR value of the sample were calculated using the stoichiometric calibration method. Compared with the Hounsfield unit (HU)-SPR calibration curve used at the EJHIC, the SPR error on each measured and theoretical value was calculated. The WEL value of the mouthpiece sample had an error of approximately 3.5% in the HU-SPR calibration curve. From this error, it was evaluated that for a mouthpiece with a thickness of 10 mm, a beam range error of approximately 0.4 mm can occur, and for a mouthpiece with a thickness of 30 mm, a beam range error of approximately 1 mm can occur. For a beam passing through the mouthpiece in HN treatment, it would be practical to consider a mouthpiece margin of 1 mm to avoid beam range errors if ions pass through the mouthpiece.

Development of a quantitative analysis method for assessing patient body surface deformation using an optical surface tracking system

This study aimed to develop a new method to quantitatively analyze body shape changes in patients during radiotherapy without additional radiation exposure using an optical surface tracking system. This method's accuracy was evaluated using a cubic phantom with a known shift. Surface images of three-dimensionally printed phantoms, which simulated the head and neck shapes of real patients before and after treatment, were used to create a deformation surface area histogram. The near-maximum deformation value covering an area of 2 cm² in the surface image (Def-2cm²) was calculated. A volumetric modulated arc therapy (VMAT) plan was also created on the pre-treatment phantom, and the dose distribution was recalculated on the post-treatment phantom to compare the dose indices. Surface images of four patients were analyzed to evaluate Def-2cm² and examine whether this method can be used in clinical cases. Experiments with the cubic phantom resulted in a mean deformation error of 0.08 mm. With head and neck phantoms, the Def-2cm² value was 17.5 mm, and the dose that covered 95% of the planning target volume in the VMAT plan decreased by 11.7%, indicating that deformation of the body surface may affect the dose distribution. Although analysis of the clinical data showed no clinically relevant deformation in any of the cases, slight skin sagging and respiratory changes in the body surface were observed. The proposed method can quantitatively and accurately evaluate the deformation of a body surface. This method is expected to be used to make decisions regarding modifications to treatment plans.

Robust treatment planning in scanned carbon-ion radiotherapy for pancreatic cancer: Clinical verification using in-room computed tomography images

Purpose

Carbon-ion beam (C-beam) has a sharp dose distribution called the Bragg peak. Carbon-ion radiation therapy, such as stereotactic body radiotherapy in photon radiotherapy, can be completed in a short period by concentrating the radiation dose on the tumor while minimizing the dose to organs at-risk. However, the stopping position of C-beam is sensitive to density variations along the beam path and such variations can lower the tumor dose as well as cause the delivery of an unexpectedly high dose to the organs at risk. We evaluated the clinical efficacy of a robust planning technique considering gastrointestinal gas (G-gas) to deliver accurate radiation doses in carbon-ion radiotherapy for pancreatic cancer.

Materials and methods

We focused on the computed tomography (CT) value replacement method. Replacement signifies the overwriting of CT values in the CT images. The most effective replacement method for robust treatment planning was determined by verifying the effects of the three replacement patterns. We selected 10 consecutive patients. Pattern 1 replaces the CT value of the G-gas contours with the value of the region without G-gas (P1). This condition indicates a no-gas state. Pattern 2 replaces each gastrointestinal contour using the mean CT value of each contour (P2). The effect of G-gas was included in the replacement value. Pattern 3 indicates no replacement (P3). We analyzed variations in the target coverage (TC) and homogeneity index (HI) from the initial plan using in-room CT images. We then performed correlation analysis on the variations in G-gas, TC, and HI to evaluate the robustness against G-gas.

Results

Analysis of variations in TC and HI revealed a significant difference between P1 and P3 and between P2 and P3. Although no statistically significant difference was observed between P1 and P2, variations, including the median, tended to be fewer in P2. The correlation analyses for G-gas, TC, and HI showed that P2 was less likely to be affected by G-gas.

Conclusion

For a treatment plan that is robust to G-gas, P2 mean replacement method should be used. This method does not necessitate any particular software or equipment, and is convenient to implement in clinical practice.

External validation of H2ARDD score for the prediction of heart failure events in patients with atrial fibrillation

Background

Heart failure is an important consequence in patients with atrial fibrillation (AF) which is associated with worse prognosis. The H2ARDD score, calculated from 5 clinical risk factors, was reported as a predictor of heart failure events in patients with AF. However, this score has not been externally validated.

Purpose

The purpose of this study was to evaluate and validate the usefulness of the H2ARDD score for the prediction of heart failure events in AF patients.

Methods

We used prospective data of patients with AF followed up from 2007 to 2017 in our institute. Patients with active cancer were excluded according to the previous report. H2ARDD score was calculated as follows; history of heart disease=2 points, anemia=1 point, renal dysfunction=1 point, diabetes =1 point, diuretic use=1 point (range from 0 to 6 points). Outcome of interest was defined as heart failure events including new-onset heart failure and death with heart failure. Heart failure was ascertained based on the Framingham criteria. Univariable and multivariable Cox-proportional hazards model were used to assess the risk of heart failure events. Heart failure events-free survival was estimated with Kaplan-Meier methods, and the predictive accuracy of the H2ARDD score for the prediction of heart failure events was measured by the area under the receiver operating characteristic (ROC) curve.

Results

Of 562 AF patients, 522 (age 69±10 year–old, 64.9%men) met study criteria. Patients who had a history of heart disease was 185 (35%), diabetes mellitus was 135 (26%), anemia was 54 (10%), renal dysfunction was 221 (43%), and diuretic use was 193 (37%). The mean H2ARDD score was 1.88±1.57. Of all study patients, 84 (16.2%) developed heart failure events during a mean follow–up of 54±42 months. Patients who developed heart failure events in 1 year was 24 (4.6%). In multivariable Cox–proportional hazards model, H2ARDD score was shown as an significant predictor for heart failure events (hazard ratio: 1.56, 95% confidence interval: 1.36 - 1.79, P&lt;0.0001), independently of age (per 10 years, hazard ratio: 1.35, 95% confidence interval: 1.03 – 1.78, P&lt;0.05). In the Kaplan–Meier analyses stratified by H2ARDD score (0–1, 2–3, 4–6), patients who had a higher H2ARDD sore had significantly worse heart failure event-free survival (log-rank P&lt;0.0001) (Figure 1). The area under the ROC curve for the prediction of heart failure events in 1-year was 0.812 (95% confidence interval: 0.737 – 0.887, P&lt;0.0001), and the best cut-off value was ≥4 points (sensitivity: 67%, specificity: 83%) (Figure 2).

Conclusion

H2ARDD score was demonstrated as a significant independent predictor for the prediction of heart failure events, with high predictive accuracy. H2ARDD score may be useful for heart failure risk stratification of AF patients.

Funding Acknowledgement

Type of funding sources: None. Figure 1Figure 2

Prediction of the minimum spacer thickness required for definitive radiotherapy with carbon ions and photons for pelvic tumors: an in silico planning study using virtual spacers

We aimed to predict the minimum distance between a tumor and the gastrointestinal (GI) tract that can satisfy the dose constraint by creating simulation plans with carbon-ion (C-ion) radiotherapy (RT) and photon RT for each case assuming insertion of virtual spacers of various thicknesses. We enrolled 55 patients with a pelvic tumor adjacent to the GI tract. Virtual spacers were defined as the overlap volume between the GI tract and the volume expanded 7-17 mm from the gross tumor volume (GTV). Simulation plans (70 Gy in 35 fractions for at least 95% of the planning target volume [PTV]) were created with the lowest possible dose to the GI tract under conditions that meet the dose constraints of the PTV. We defined the minimum thickness of virtual spacers meeting D2 cc of the GI tract <50 Gy as 'MTS'. Multiple regression was used with explanatory variables to develop a model to predict MTS. We discovered that MTSs were at most 9 mm and 13 mm for C-ion RT and photon RT plans, respectively. The volume of overlap between the GI tract and a virtual spacer of 14 mm in thickness (OV14)-PTV was found to be the most important explanatory variable in the MTS prediction equation for both C-ion and photon RT plans. Multiple R2 values for the regression model were 0.571 and 0.347 for C-ion RT and photon RT plans, respectively. In conclusion, regression equations were developed to predict MTS in C-ion RT and photon RT.

Comparison of predictive performance for toxicity by accumulative dose of DVH parameter addition and DIR addition for cervical cancer patients

We compared predictive performance between dose volume histogram (DVH) parameter addition and deformable image registration (DIR) addition for gastrointestinal (GI) toxicity in cervical cancer patients. A total of 59 patients receiving brachytherapy and external beam radiotherapy were analyzed retrospectively. The accumulative dose was calculated by three methods: conventional DVH parameter addition, full DIR addition and partial DIR addition. ${D}_{2{cm}^3}$, ${D}_{1{cm}^3}$ and ${D}_{0.1{cm}^3}$ (minimum doses to the most exposed 2 cm3, 1cm3 and 0.1 cm3 of tissue, respectively) of the rectum and sigmoid were calculated by each method. V50, V60 and V70 Gy (volume irradiated over 50, 60 and 70 Gy, respectively) were calculated in full DIR addition. The DVH parameters were compared between toxicity (≥grade1) and non-toxicity groups. The area under the curve (AUC) of the receiver operating characteristic (ROC) curves were compared to evaluate the predictive performance of each method. The differences between toxicity and non-toxicity groups in ${D}_{2{cm}^3}$ were 0.2, 5.7 and 3.1 Gy for the DVH parameter addition, full DIR addition and partial DIR addition, respectively. The AUCs of ${D}_{2{cm}^3}$ were 0.51, 0.67 and 0.57 for DVH parameter addition, full DIR addition and partial DIR addition, respectively. In full DIR addition, the difference in dose between toxicity and non-toxicity was the largest and AUC was the highest. AUCs of V50, V60 and V70 Gy were 0.51, 0.63 and 0.62, respectively, and V60 and V70 were high values close to the value of ${D}_{2{cm}^3}$ of the full DIR addition. Our results suggested that the full DIR addition may have the potential to predict toxicity more accurately than the conventional DVH parameter addition, and that it could be more effective to accumulate to all pelvic irradiation by DIR.

Usefulness of H2FPEF score as an independent predictor of heart failure development in patients with atrial fibrillation

Background

The H2 FPEF score, which based on simple clinical characteristics and echocardiography, enables discrimination of HFpEF from noncardiac causes of dyspnea.

Purpose

We sought to evaluate whether H2 FPEF score predicts congestive heart failure (CHF) development in patients with atrial fibrillation (AF).

Methods

Among adult AF patients who underwent transthoracic echocardiography between July 2007 and December 2008, those with preserved left ventricular ejection fraction (LVEF) (≥50%) were included and followed up to new-onset CHF events. Patients with a history of CHF, cardiac surgery, or significant left-sided valvular heart disease were excluded. The H2 FPEF score was calculated from 6 variables (obesity = 2 points, treatment with ≥2 antihypertensive drugs = 1 point, AF = 3 points, echocardiographic pulmonary artery systolic pressure &gt;35 mmHg = 1 point, age &gt;60 years = 1 point, and echocardiographic E/e'ratio &gt;9 = 1 point). CHF was ascertained using Framingham criteria. Cox-proportional hazards modeling was used to assess risk of CHF development.

Results

Of 562 AF patients, 367 (69±10 year old, 66% men) met all study criteria. Of whom, 37 (10%) developed CHF events during a mean follow–up of 56±43 months. The mean H2 FPEF score was 5.50±1.14, and the number of patients with H2 FPEF score ≥7 was 64 (17%). After adjusting for comorbidities in a multivariate model, H2 FPEF score was significant predictor of new-onset CHF events both as continuous (HR=1.43, 95% CI: 1.05–1.96, P&lt;0.05) or categorical (H2 FPEF score ≥7) (HR=2.32, 95% CI: 1.17–4.63, P&lt;0.05) variables. The Kaplan-Meier estimates of CHF-free survival stratified by H2 FPEF status (≥7 or &lt;7) were shown in Figure.

Conclusion

H2 FPEF score provides prognostic information for new-onset CHF development in patients with AF.

Figure 1

Funding Acknowledgement

Type of funding source: None

The impact of 4DCT-ventilation imaging-guided proton therapy on stereotactic body radiotherapy for lung cancer

Functional lung avoidance during radiotherapy can help reduce pulmonary toxicity. This study assessed the potential impact of four-dimensional computed tomography (4DCT)-ventilation imaging-guided proton radiotherapy (PT) on stereotactic body radiotherapy (SBRT) by comparing it with three-dimensional conformal radiotherapy (3D-CRT) and volumetric modulated arc therapy (VMAT), which employ photon beams. Thirteen lung cancer patients who received SBRT with 3D-CRT were included in the study. 4DCT ventilation was calculated using the patients' 4DCT data, deformable image registration, and a density-change-based algorithm. Three functional treatment plans sparing the functional lung regions were developed for each patient using 3D-CRT, VMAT, and PT. The prescribed doses and dose constraints were based on the Radiation Therapy Oncology Group 0618 protocol. We evaluated the region of interest (ROI) and functional map-based dose-function metrics for 4DCT ventilation and the irradiated dose. Using 3D-CRT, VMAT, and PT, the percentages of the functional lung regions that received ≥ 5 Gy (fV5) were 26.0%, 21.9%, and 10.7%, respectively; the fV10 were 14.4%, 11.4%, and 9.0%, respectively; and fV20 were 6.5%, 6.4%, and 6.6%, respectively, and the functional mean lung doses (fMLD) were 5.6 Gy, 5.2 Gy, and 3.8 Gy, respectively. These results indicated that PT resulted in a significant reduction in fMLD, fV5, and fV10, but not fV20. The use of PT reduced the radiation to highly functional lung regions compared with those for 3D-CRT and VMAT while meeting all dose constraints.

Quantitative analysis of intra-fractional variation in CT-based image guided brachytherapy for cervical cancer patients

We quantified intra-fractional dose variation and organ movement during CT-based 3D-image guided brachytherapy (3D-IGBT) in cervical cancer patients. Fifteen patients who underwent CT-based 3D-IGBT were studied. For all patients, pre-delivery CT for treatment planning after applicator insertion and post-delivery CT after dose delivery without changing the applicator position were acquired. Pre- and post-delivery CT were rigidly fused by matching the inserted applicator and planned dose on pre-delivery CT (pre-delivery dose) was mapped on post-delivery CT (post-delivery dose). D2, D1, and D0.1 cm³ of the rectum and bladder were compared between pre- and post-delivery doses with contours on each CT image. Organ movement and deformation was evaluated using deformation vector fields calculated by deformable image registration between pre- and post-delivery CT. We also evaluated dose variation and DVF between with and without a catheter to control filling. Differences in all DVH parameters were <±3% in physical dose and ± 5% in EQD2. However, a > 15% dose difference was found in 13.8% of the fractions in rectum D2 cm³ and in 11.1% of those in bladder D2 cm³. The mean value of DVF for bladder was larger than that of rectum, especially for the superior-inferior (S-I) direction. Insertion catheters in bladder reduced mean dose and DVF variation compared with that of without catheters. In fraction groups with large dose increasing, DVF in the S-I direction was significantly larger than that of other fraction groups. Our results indicated that preparation is needed to reduce changes in the S-I direction affect dose variation.

In silico comparison of the dosimetric impacts of a greater omentum spacer for abdominal and pelvic tumors in carbon-ion, proton and photon radiotherapy

Purpose

The purpose of this study was to compare carbon-ion (C-ion), proton and photon radiotherapy (RT) plans with regard to dose reduction of the gastrointestinal (GI) tract by using a greater omentum spacer (GO spacer).

Methods

We retrospectively retrieved data for ten patients who received the GO spacer as surgical spacer placement for abdominal and pelvic tumors. Simulation plans were created on pre-spacer Computed Tomography (CT) and post-spacer CT for C-ion RT, proton RT and photon RT to compare the dose of the GI tract. The plans were normalized so that at least 95% of the planning target volume (PTV) received 70 Gy (relative biological effectiveness equivalent) delivered in 35 fractions. All plans were created with the lowest possible dose to the GI tract under conditions that meet the dose constraints for the PTV and spinal cord (maximum dose < 45 Gy). The part of the GI tract to be evaluated was defined as that most adjacent to the PTV. C-ion RT plans and proton RT plans were calculated by a spot scanning technique, and photon RT plans were calculated employing by fixed-field intensity-modulated radiation therapy.

Results

D2 cc and V10–70 of the GI tract were significantly lower on post-spacer plans than on pre-spacer plans for all three RT modalities. Regarding post-spacer plans, D2 cc of the GI tract was significantly lower on C-ion RT plans and proton RT plans than on photon RT plans (C-ion vs photon p = 0.001, proton vs photon p = 0.002). However, there was no significant difference between C-ion RT plans and proton RT plans for D2 cc of the GI tract (C-ion vs proton p = 0.992). In the photon RT plan for one patient, D2 cc of the GI tract did not meet < 50 Gy.

Conclusions

The GO spacer shows a significant dose reduction effect on the GI tract.

P303Prognostic value of diastolic wall strain in patients with asymptomatic severe aortic stenosis

Background

Diastolic wall strain (DWS) has been reported to be associated with left ventricular (LV) stiffness and worse clinical outcomes. We sought to assess the utility of this new index for prediction of prognosis in asymptomatic patients with severe aortic stenosis (AS).

Methods

Asymptomatic severe AS patients [peak flow velocity (PFV) ≥4.0m/s, mean pressure gradient (mPG) ≥40mmHg, aortic valve area (AVA) ≤1.0cm2, or indexed AVA ≤0.6cm2/m2)] diagnosed between July 2007 and April 2016 were included in this study. Patients with significant mitral valve disease, posterior wall motion abnormality, prior cardiac surgery, hypertrophic cardiomyopathy, and LV ejection fraction <50% were excluded. DWS was calculated with a validated formula [DWS = (posterior wall thickness at end-systole − posterior wall thickness at end-diastole)/posterior wall thickness at end-systole]. All study patients were prospectively followed up to last visit or death until November 2017, and predictive value of all-cause death was assessed using Cox-proportional hazards modeling. Patients who underwent aortic valve replacement (AVR) during the study period were censored on the date of surgery.

Results

A total of 184 asymptomatic severe AS, 138 (age 76±9year-old, men 41%, PFV 3.9±1.0m/s, mPG 38±19mmHg, AVA 0.83±0.18cm2, indexed AVA 0.56±0.13cm2/m2) met all study criteria. Of whom, 43 (31%) underwent AVR and 28 (20%) died during a mean follow-up of 25±28months. In a multivariable model after adjusting for clinical and echocardiographic variables, advancing age (per10yrs; HR=2.19, 95% CI=1.19–4.03, P<0.05), history of hemodialysis (HR=4.31, 95% CI=1.30–14.35, P<0.05), and low-DWS (DWS <0.30) (HR=2.83, 95% CI=1.25–6.40, P<0.05) were independent predictors of all-cause death. In the Kaplan-Meier estimates of cumulative survival stratified by DWS status were shown (Figure).

The Kaplan-Meier estimates of survival

Conclusion

Low-DWS provides prognostic information in patients with asymptomatic severe AS.

Impact of a commercially available model-based dose calculation algorithm on treatment planning of high-dose-rate brachytherapy in patients with cervical cancer

We evaluated the impact of model-based dose calculation algorithms (MBDCAs) on high-dose-rate brachytherapy (HDR-BT) treatment planning for patients with cervical cancer. Seven patients with cervical cancer treated using HDR-BT were studied. Tandem and ovoid applicators were used in four patients, a vaginal cylinder in one, and interstitial needles in the remaining two patients. MBDCAs were applied to the Advanced Collapsed cone Engine (ACE; Elekta, Stockholm, Sweden). All plans, which were originally calculated using TG-43, were re-calculated using both ACE and Monte Carlo (MC) simulations. Air was used as the rectal material. The mean difference in the rectum D2cm3 between ACErec-air and MCrec-air was 8.60 ± 4.64%, whereas that in the bladder D2cm3 was -2.80 ± 1.21%. Conversely, in the small group analysis (n = 4) using water instead of air as the rectal material, the mean difference in the rectum D2cm3 between TG-43 and ACErec-air was 11.87 ± 2.65%, whereas that between TG-43 and ACErec-water was 0.81 ± 2.04%, indicating that the use of water as the rectal material reduced the difference in D2cm3 between TG-43 and ACE. Our results suggested that the differences in the dose-volume histogram (DVH) parameters of TG-43 and ACE were large for the rectum when considerable air (gas) volume was present in it, and that this difference was reduced when the air (gas) volume was reduced. Also, ACE exhibited better dose calculation accuracy than that of TG-43 in this situation. Thus, ACE may be able to calculate the dose more accurately than TG-43 for HDR-BT in treating cervical cancers, particularly for patients with considerable air (gas) volume in the rectum.

Evaluation of the performance of deformable image registration between planning CT and CBCT images for the pelvic region: comparison between hybrid and intensity-based DIR

This study aimed to evaluate the performance of the hybrid deformable image registration (DIR) method in comparison with intensity-based DIR for pelvic cone-beam computed tomography (CBCT) images, using intensity and anatomical information. Ten prostate cancer patients treated with intensity-modulated radiation therapy (IMRT) were studied. Nine or ten CBCT scans were performed for each patient. First, rigid registration was performed between the planning CT and all CBCT images using gold fiducial markers, and then DIR was performed. The Dice similarity coefficient (DSC) and center of mass (COM) displacement were used to evaluate the quantitative DIR accuracy. The average DSCs for intensity-based DIR for the prostate, rectum, bladder, and seminal vesicles were 0.84 ± 0.05, 0.75 ± 0.05, 0.69 ± 0.07 and 0.65 ± 0.11, respectively, whereas those values for hybrid DIR were 0.98 ± 0.00, 0.97 ± 0.01, 0.98 ± 0.00 and 0.94 ± 0.03, respectively (P < 0.05). The average COM displacements for intensity-based DIR for the prostate, rectum, bladder, and seminal vesicles were 2.0 ± 1.5, 3.7 ± 1.4, 7.8 ± 2.2 and 3.6 ± 1.2 mm, whereas those values for hybrid DIR were 0.1 ± 0.0, 0.3 ± 0.2, 0.2 ± 0.1 and 0.6 ± 0.6 mm, respectively (P < 0.05). These results showed that the DSC for hybrid DIR had a higher DSC value and smaller COM displacement for all structures and all patients, compared with intensity-based DIR. Thus, the accumulative dose based on hybrid DIR might be trusted as a high-precision dose estimation method that takes into account organ movement during treatment radiotherapy.

Laparoscopy-Assisted Spleen-Preserving Distal Pancreatectomy for Living-Donor Pancreas Transplantation

BACKGROUND

Living pancreas transplantation plays an important role in the treatment of patients with severe type 1 diabetes. However, pancreatectomy is very invasive for the donor, and less-invasive surgical procedures are needed. Although some reports have described hand-assisted laparoscopic surgery for distal pancreatectomy in living-donor operations, less-invasive laparoscopy-assisted (LA) procedures are expected to increase the donor pool. We herein report the outcomes of four cases of LA spleen-preserving distal pancreatectomy (Warshaw technique [WT]) in living pancreas donors.

PATIENTS AND METHODS

Four living pancreas donors underwent LA-WT at our institution from September 2010 to January 2013. All donors fulfilled the donor criteria established by the Japan Society for Pancreas and Islet Transplantation.

RESULTS

The median donor age was 54 years. Two donors underwent left nephrectomy in addition to LA-WT for simultaneous pancreas-kidney transplantation. The median donor operation time for pancreatectomy was 340.5 minutes. The median pancreas warm ischemic time was 3 minutes. The median donor blood loss was 246 g. All recipients immediately achieved insulin independence. One donor required reoperation because of obstructive ileus resulting from a port-site hernia. Another donor developed a pancreatic fistula (International Study Group of Pancreatic Fistula grade B), which was controlled with conservative management. After a maximum follow-up of 73 months, no clinically relevant adverse events had occurred. These results were comparable with those of previous studies concerning living-donor pancreas transplantation.

CONCLUSION

The LA-WT is a safe and acceptable operation for living-donor pancreas transplantation.

Evaluation of deformable image registration between external beam radiotherapy and HDR brachytherapy for cervical cancer with a 3D-printed deformable pelvis phantom

PURPOSE

In this study, we developed a 3D-printed deformable pelvis phantom for evaluating spatial DIR accuracy. We then evaluated the spatial DIR accuracies of various DIR settings for cervical cancer.

METHODS

A deformable female pelvis phantom was created based on patient CT data using 3D printing. To create the deformable uterus phantom, we first 3D printed both a model of uterus and a model of the internal cavities of the vagina and uterus. We then made a mold using the 3D printed uterus phantom. Finally, urethane was poured into the mold with the model of the internal cavities in place, creating the deformable uterus phantom with a cavity into which an applicator could be inserted. To create the deformable bladder phantom, we first 3D printed models of the bladder and of the same bladder scaled down by 2 mm. We then made a mold using the larger bladder model. Finally, silicone was poured into the mold with the smaller bladder model in place to create the deformable bladder phantom with a wall thickness of 2 mm. To emulate the anatomical bladder, water was poured into the created bladder. We acquired phantom image without applicator for EBRT. Then, we inserted the applicator into the phantom to simulate BT. In this situation, we scanned the phantom again to obtain the phantom image for BT. We performed DIR using the two phantom images in two cases: Case A, with full bladder (170 ml) in both EBRT and BT images; and Case B with full bladder in the BT image and half-full bladder (100 ml) in the EBRT image. DIR was evaluated using Dice similarity coefficients (DSCs) and 31 landmarks for the uterus and 25 landmarks for the bladder. A hybrid intensity and structure DIR algorithm implemented in RayStation with four DIR settings was evaluated.

RESULTS

On visual inspection, reasonable agreement in shape of the uterus between the phantom and patient CT images was observed for both EBRT and BT, although some regional disagreements in shape of the bladder and rectum were apparent. The created phantom could reproduce the actual patient's uterus deformation by the applicator. For both Case A and B, large variation was seen in landmark error among the four DIR parameters. In addition, although DSCs were comparable, moderate differences in landmark error existed between the two different DIR parameters selected from the four DIR parameters (i.e., DSC = 0.96, landmark error = 13.2 ± 5.7 mm vs. DSC = 0.97, landmark error = 9.7 ± 4.0 mm). This result suggests that landmark error evaluation might thus be more effective than DSC for evaluating DIR accuracy.

CONCLUSIONS

Our developed phantom enabled the evaluation of spatial DIR accuracy for the female pelvic region for the first time. Although the DSCs are high, the spatial errors can still be significant and our developed phantom facilitates their quantification. Our results showed that optimization is needed to identify suitable DIR settings. For determining suitable DIR settings, our method of evaluating spatial DIR accuracy using the 3D-printed phantom may prove helpful.

Evaluating the Toxicity Reduction With Computed Tomographic Ventilation Functional Avoidance Radiation Therapy

PURPOSE

Computed tomographic (CT) ventilation imaging is a new modality that uses 4-dimensional (4D) CT information to calculate lung ventilation. Although retrospective studies have reported on the reduction in dose to functional lung, no work to our knowledge has been published in which the dosimetric improvements have been translated to a reduction in the probability of pulmonary toxicity. Our work estimates the reduction in toxicity for CT ventilation-based functional avoidance planning.

METHODS AND MATERIALS

Seventy previously treated lung cancer patients who underwent 4DCT imaging were used for the study. CT ventilation maps were calculated with 4DCT deformable image registration and a density change-based algorithm. Pneumonitis was graded on the basis of imaging and clinical presentation. Maximum likelihood methods were used to generate normal tissue complication probability (NTCP) models predicting grade 2 or higher (2+) and grade 3+ pneumonitis as a function of dose (V5 Gy, V10 Gy, V20 Gy, V30 Gy, and mean dose) to functional lung. For 30 patients a functional plan was generated with the goal of reducing dose to the functional lung while meeting Radiation Therapy Oncology Group 0617 constraints. The NTCP models were applied to the functional plans and the clinically used plans to calculate toxicity reduction.

RESULTS

By the use of functional avoidance planning, absolute reductions in grade 2+ NTCP of 6.3%, 7.8%, and 4.8% were achieved based on the mean fV20 Gy, fV30 Gy, and mean dose to functional lung metrics, respectively. Absolute grade 3+ NTCP reductions of 3.6%, 4.8%, and 2.4% were achieved with fV20 Gy, fV30 Gy, and mean dose to functional lung. Maximum absolute reductions of 52.3% and 16.4% were seen for grade 2+ and grade 3+ pneumonitis for individual patients.

CONCLUSION

Our study quantifies the possible toxicity reduction from CT ventilation-based functional avoidance planning. Reductions in grades 2+ and 3+ pneumonitis were 7.1% and 4.7% based on mean dose-function metrics, with reductions as high as 52.3% for individual patients. Our work provides seminal data for determining the potential toxicity benefit from incorporating CT ventilation into thoracic treatment planning.

Preparation of SrTiO3 Thin Films by Ecr and Thermal Mocvd

SrTiO3 thin films were prepared by ECR and thermal MOCVD. In thermal-CVD mode, Sr content and Ti content were at a maximum at 0.56 Torr. Results showed that SrO deposition is a surface reaction limited process between 500 and 650°C, whereas TiO2 deposition is surface reaction limited between 500 and 600 °C, and diffusion limited above 600 °C. At a low pressure of 8 mTorr, ECR oxygen plasma was found to help decompose Ti(i-OC3H7)4. In ECR-CVD mode, the deposition temperature could be lowered to 400 °C. TEM and SEM analyses showed that SrTiO3 thin films have a columnar structure. The size of the grains depends on film thickness, and their shape on film composition (Sr/Ti ). Films prepared by thermal-CVD had a lateral step coverage of 50 %. 40 nm SrTiO3 thin films (Sr/Ti = 1.0) prepared by thermal-CVD on Pt/TaOx/Si and annealed for 2 hours in O2 had a maximum dielectric constant of 139 (Cs = 31 fF/μm2 and teq = 1.1 nm) and a leakage current density of 6x10−8 A/cm2 at 1.0 V.

Interface Structure and Dielectric Properties of SrTiO3 Thin Film Sputter-Deposited onto Si Substrates

SrTiO3 thin film preparation onto Si substrates using RF magnetron sputtering has been studied for a high capacitance density required for the next generation of LSI's. Structural and chemical analysis on the interface between SrTiO3 film and Si was carried out with cross-sectional TEM, EDX, and AES. Dielectric properties were measured on AuTi/SrTiO3/Si/Ti/Au capacitors. The as-grown dielectric films on Si were analyzed and found to consist of three layers; SiO2, amorphous SrTiO3 and crystalline SrTiO3, from interface toward film surface. By annealing at 600 °C, the amorphous SrTiO3 layer was recrystallized, and consequently the capacitance value increased. A typical specific capacitance was 4.7 fF/μm2 and the leakage current was in the order of 10−8 A/cm2, for 180 nm thick SrTiO3 film. The dielectric constant decreased from 147 to 56 with decreasing SrTiO3 film thickness from 480 nm to 80 nm. This is due to the low dielectric constant SiO2 layer (ε=3.9) at the interface. From the film thickness dependence of the ε value, the SiO2 layer thickness was calculated to be 3.9 nm, which agreed well with the value directly observed in the TEM.

To avoid SiO2 layer formation, barrier layers between SrTiO3 and Si have been studied. Among various refractory and noble metals, RuSi and a multi-layer of Pt/Ti have been found to be promising candidates for the barrier material. When RuSi film or Pt/Ti film was formed between SrTiO3 film and Si substrate, dielectric constant of about 190 was obtained in dependent of the SrTiO3 film thickness in the range of 80–250 nm. Analysis on the barrier layers was performed by means of RBS, XPS and XRD.

Over-expression of S100A2 in pancreatic cancer correlates with progression and poor prognosis

Controversy exists regarding the clinical significance of S100A2 in the progression of tumours. In pancreatic cancer, little is known about the role of S100A2. The aim of this study was to clarify the clinical significance of S100A2 expression in pancreatic carcinogenesis. We microdissected invasive ductal carcinoma (IDC) cells from 22 lesions, pancreatic intraepithelial neoplasia (PanIN) cells from five lesions, intraductal papillary mucinous neoplasm (IPMN) cells from 38 lesions, pancreatitis-affected epithelial (PAE) cells from 16 lesions, and normal ductal cells from 18 normal pancreatic tissues. S100A2 expression in 14 pancreatic cancer cell lines, microdissected cells and formalin-fixed paraffin-embedded (FFPE) samples was examined by quantitative reverse transcription-polymerase chain reaction (qRT-PCR). Microdissection analyses revealed that IDC cells expressed higher levels of S100A2 than did IPMN, PAE or normal cells (all comparisons, p < 0.007). Cell lines from metastatic sites expressed higher levels of S100A2 than those from primary sites. PanIN cells expressed higher levels of S100A2 than normal cells (p = 0.018). IDC cells associated with poorly differentiated adenocarcinoma expressed higher levels of S100A2 than did IDC cells without poorly differentiated adenocarcinoma (p = 0.006). Analyses of FFPE samples revealed that levels of S100A2 were higher in samples from patients who survived < 1000 days after surgery than in those from patients who survived > 1000 days (p = 0.043). Immunohistochemical analysis was consistent with qRT-PCR. S100A2 may be a marker of tumour progression or prognosis in pancreatic carcinogenesis and pancreatic cancer.

[21-year-old man with squamous cell carcinoma of the lung]

Lung cancer among people in their twenties is rare and accounts for only 0.1-0.4% of all cases. We describe a case of squamous cell carcinoma of the lung in a 21-year-old man. The otherwise healthy patient presented with a 1 month history of cough. Chest radiography showed a well-defined round mass 5 cm in size in the right lower lobe. Computed tomography also showed a 3 cm hilar lymph node. Bronchoscopy revealed a white polypoid mass obstructing the right basal bronchus. Transbronchial biopsy revealed poorly differentiated squamous cell carcinoma of the lung. Clinical diagnosis was T2N1M0, stage IIB lung cancer. Right lower lobectomy with mediastinal lymph node dissection was performed. Lymph node metastases were proven histologically in the pretracheal, subcarinal, hilar, and intrapulmonary regions. Pathological diagnosis was T2N2M0, stage IIIA lung cancer. Endobronchial and mediastinal lymph node metastases were found 2 months after surgery. He received 3 rounds of chemotherapy with cisplatin and docetaxel and irradiation to the right hilum and mediastinum at a total dose of 60 Gy in 30 fractions. He is alive 6 months after surgery.

Endovascular surgery for ruptured aneurysms with vasospasm

SUMMARY

With the existence of vasospasm, it is recommended that direct clipping surgery for a ruptured aneurysm be delayed until its disappearance, but this may be associated with aneurysmal re-rupture resulting in a poor outcome for the patients. Indications for endovascular coil embolization in such cases are discussed. Since November in 2003, we have applied endovascular coil embolization in 11 consecutive patients with ruptured aneurysms and apparent vasospasm of the parent artery from two to 17 days (average: eight days) after initial subarachnoid hemorrhage. Three patients had aneurysmal re-rupture before treatment, but the other eight had only experienced the one episode of subarachnoid hemorrhage. With one exception, all endovascular procedures could be successfully performed, resulting in complete occlusion of aneurysms and remarkable dilatation of inserted spastic vessels without technical complications or aneurysmal re-rupture. For the one case of failure because of a tortuous artery, direct clipping surgery was performed after disappearance of vasospasm. Cerebral infarction occurred in four, but only one correlated with the distribution of catheterization, and neurological deficits had completely disappeared three months after the onset. This preliminary report concerning a small number of patients suggests that endovascular coil embolization is not contra-indicated for aneurysms with vasospasm requiring catheterization. A large study for confirmation is now warranted.

Detection of small particles in fluid flow using a self-mixing laser

We describe a highly sensitive, real-time method of detecting small particles in a fluid flow by self-mixing laser Doppler measurement with a laser-diode-pumped, thin-slice solid-state laser with extremely high optical sensitivity. Asymmetric power spectra of the laser output modulated by the re-injected scattered light from the small particles moving in a dilute sample-flow, through a small-diameter glass pipe, were observed. The observed power spectra are shown to reflect the velocity distribution of the fluid flow, which obeys Poiseuille's law. Quick measurements of flow rate and kinetic viscosities of water-glycerol mixtures were also performed successfully. Measurable low-concentration limits for 262-nm polystyrene latex spheres and 3-mum red blood cells in a fluid flow were below 1 and 10 ppm, respectively, in the present self-mixing laser Doppler velocimeter system.

[Endobronchial neurinoma treated with left lower lobectomy]

Benign endobronchial tumors are rare, and among these endobronchial neurinoma is extremely rare. We describe a case of endobronchial neurinoma successfully treated with left lower lobectomy. A 58-year-old man presented with an 8-month history of cough. During this period he was repeatedly treated with antibiotics for pneumonia of the left lower lobe. Chest X-ray showed atelectasis of the left lower lobe. Computed tomography (CT) of the chest showed a mass in the left main and lower lobe bronchi. Bronchoscopy revealed the mass almost completely obstructing the left main bronchus. Although transbronchial biopsy was inconclusive and yielded necrotic tissue with Aspergillus hyphae, lung cancer was highly suspected based on clinical and radiographic findings. He underwent left lower lobectomy and was discharged 14 days after surgery in good condition. Pathological diagnosis was an endobronchial neurinoma 4 cm in size arising from the left basal bronchus. On immunohistochemical staining, the tumor was positive for S-100 protein and negative for a-smooth muscle actin. He took itraconazole at a daily dose of 200 mg orally for 6 months. He remains well 52 months after surgery without any evidence of recurrence.

[Diffuse malignant pleural mesothelioma]

Malignant pleural mesothelioma is an uncommon neoplasm that caused 647 deaths in Japan in 2004. The incidence of the disease is increasing and is estimated to reach its peak in 2025. We reviewed the clinical features in 11 consecutive patients with pathologically confirmed diffuse malignant pleural mesothelioma in our institution from January 1997 to December 2002. Of the 11 patients, 9 were male and 2 were female with a mean age of 66 (range, 55 to 90) years. Symptoms included dyspnea in 4 patients, chest pain in 3, dyspnea plus chest pain in 2, and cough in 2. Median period between symptom onset and presentation was 1 (range, 0 to 6) month. A history of asbestos exposure was identified in 3 patients and suspected in 5. A definitive diagnosis was made by closed pleural biopsy in 8 patients, pleural fluid cytology in 2, and autopsy in 1. Histological subtypes included epithelioid in 6 patients, sarcomatoid in 2, biphasic in 1, and unknown in 2. International Mesothelioma Interest Group (IMIG) staging included stage II in 6 patients, stage III in 3, and stage IV in 2. Median period between presentation and diagnosis was 1 (range, 0 to 22) month. Treatment included intrapleural chemotherapy in 4 patients, extrapleural pneumonectomy in 3, pleural drainage in 2, and best supportive care in 2. During the follow-up period, 9 patients died and 2 survived. Median survival time after diagnosis was 3 (range, 0 to 51) months. Of the 11 patients, 7 (64%) died within 6 months after the first presentation, and only 1 (9%) lived longer than 2 years after diagnosis.

Successful coil embolization for a "three-hump" internal carotid artery anterior wall aneurysm: a case report

SUMMARY

We describe an unusually shaped aneurysm arising from the anterior wall of the internal carotid artery (ICA) that was treated successfully with Guglielmi detachable coils (GDCs). A 38-year-old woman presented with sudden onset of headache and was transferred to our hospital. Computed tomography revealed thin subarachnoid hemorrhage in the basal cisterns. Three-dimensional rotational angiography clearly showed a "three-hump" anterior wall aneurysm of the ICA. The two distal humps of the aneurysm were successfully obliterated with GDCs, but the proximal hump was too small to treat by coil embolization. The patient was discharged without neurological deficit. Anterior wall (blisterlike) aneurysms of the ICA have a high risk of rupture due to fragility of the wall. These aneurysms are considered difficult to manage by traditional surgical approaches. Our experience suggests that endovascular GDC embolization is a good alternative treatment modality for patients with such an aneurysm.

[Long-term survival following multimodality treatment of metachronous metastases (parotid gland, adrenal gland, brain and mediastinal lymph node) after resection of non-small cell lung cancer; report of a case]

We describe a case of long-term survival following multimodality treatment of metachronous metastases (parotid gland, adrenal gland, brain and mediastinal lymph node) after resection of non-small cell lung cancer. A 72-year-old man had a past history of right upper lobectomy for pT3N0M0 tubular adenocarcinoma of the lung 12 years ago and left lower lobectomy for pT3N1M0 papillary adenocarcinoma of the lung 42 months ago, and left parotidectomy and irradiation to the neck for parotid metastasis 20 months ago. A progressive increase in serum CEA level during the follow-up period revealed a 5 cm left adrenal mass and small (1 cm or less) multiple brain metastases, and a 2 cm mediastinal lymph node. He underwent adrenalectomy and gamma knife surgery and received irradiation to the mediastinum, and was administered gefitinib as first-line chemotherapy for about a year. Brain metastases recurred despite 4 more rounds of gamma knife surgery and 4 cycles of docetaxel hydrate as second-line chemotherapy, and 1 cycle of vinorelbine ditartrate as third-line chemotherapy. He died of multiple brain metastases 65 months postoperatively. We confirm the possibility of long-term survival following multimodality treatment even though multiple organ metastases were found after resection of non-small cell lung cancer.

Application of the liquid coil as an embolic material for arteriovenous malformations

SUMMARY

The purpose of this paper is to clarify advantages and disadvantages of platinum liquid coils as an embolic material for AVMs. During the last eight years, 50 endovascular procedures using liquid coils were conducted in our institute for 19 cases with AVMs, 15 of which were located in the eloquent area. All but one presented with haemorrhage, the exception demonstrating repeated ischemic symptoms. Only liquid coils were used as the embolic material to obliterate the nidus and feeders. In ten of the 15 patients with AVMs located in the eloquent area and one case rejecting surgery, liquid coil embolization was applied one to 11 times (average 3.5 times) to achieve decrease in size and this was then followed by radiosurgery. The remaining eight AVM patients underwent total removal after liquid coil embolization. No complications were encountered during the peri-embolization period. In all cases, the purpose of embolization was to diminish the size to facilitate radiosurgery and decrease bleeding during surgery. The liquid coil has advantages as a material for embolization of AVMs; it is non-toxic and bioinart material; it seldom occludes normal minute vascular channels; when it used in a nidus, it seldom to migrates in the venous direction, and it has good radio-opacity and offers good marking for surgery. Appropriate applications include preoperative embolization or pre-radiosurgical embolization of AVMs, especially when staged embolizations are performed to reduce risk of perfusion pressure breakthrough in patients which are large or located in the eloquent area.

Differential gene-expression profiles associated with gastric adenoma

Gastric adenomas may eventually progress to adenocarcinomas at varying rates. The purpose of the present study was to identify gene-expression profiles linked to the heterogeneous nature of gastric adenoma as compared to adenocarcinoma. Suppression subtractive hybridisation analysis was performed to extract relevant genes from two cases of low- and high-grade gastric adenomas. The identified genes were quantified by RT-PCR in 14 low-grade adenoma, nine high-grade adenoma and nine adenocarcinoma samples, followed by hierarchical clustering analysis to separate tumours into groups according to their gene-expression profiles. Nine genes previously implicated in carcinogenesis in a variety of organs, including three genes related to gastric adenocarcinoma, were identified. The overexpression of these genes in gastric adenoma has not been reported previously. The clustering analysis of these nine genes across 32 cases identified three groups, one of which consisted primarily of adenocarcinomas, whereas the other two groups consisted of adenomas. One group of adenomas, characterised by larger tumour size, exhibited gene-expression profiles of an intestinal cell lineage implicated in the pathogenesis of an intestinal-type gastric adenocarcinoma. Another adenoma group consisting of low-grade adenomas with smaller tumour size exhibited a unique expression profile. In conclusion, clustering analysis of expression profiles using a limited number of genes may serve as molecular markers for gastric adenoma with different biological properties. Although the prognostic values of these gene-expression profiles need to be evaluated in further follow-up study of adenoma cases, these findings add new insights to (a) our understanding of the pathogenesis of gastric tumours, (b) the development of specific tumour markers for clinical practice, and (c) the design of novel therapeutic targets.

Superselective arterial chemotherapy for inoperable metastases in the dura mater and cranium

SUMMARY

Diffuse metastases to the cranium and dura mater of the bilateral hemisphere do not allow surgical intervention. We describe an excellent case which was treated by intra-arterial chemotherapy using Epirubicine (Farumorbicine). A 58-year-old woman treated for breast cancer ten years ago was admitted to our hospital with headache and frontal mass lesions.Magnetic resonance (MR) imaging on admission revealed a remarkable enhanced lesion of the bilateral dura mater and cranium, and bilateral brain edema in the frontal lobe. Angiography disclosed a vascular rich tumour supplied by bilateral external carotid artery branches.We successfully treated the lesion using superselective intra-arterial chemotherapy with a minimal dose of Epirubicine followed by embolization of bilateral external carotid artery branches. Followup MR imaging two years after the endovascular treatment showed disappearance of the enhanced lesion and remodeling of the skull bone. The patient is neurologically free of symptoms.