Max Point Research Articles

A Study of the Usefulness of Self‐Assessment Memory Scale (SAMS) for the Elderly in the Community

AbstractBackgroundIt is very important to detect a slight cognitive decline and start therapies at the very early stage as soon as possible. We have established a new method named the Self‐Assessment Memory Scale (SAMS), consisting of 8‐picture recall and 16‐word recognition test. This study examined the usefulness and validity of SAMS in older adults participating in a dementia prevention (J‐MINT PRIME Tamba) study.MethodThe subjects were 97 older adults aged 65 year or older (24 men). The subject was administered a test consisting of an 8‐picture recall and a 16‐word recognition test on a tablet twice on separate days. The SAMS index was calculatedby adding up the ratio of correct responses to both tests (max point is two). The correlation with the WMS‐R logical memory II (LMII) score was examined.ResultThe mean and standard deviation of SAMS for the subjects in this study by age groups 65‐69, 70‐74, 75‐79 and 80‐ were 1.71 ± 0.24, 1.55 ± 0.25, 1.36 ± 0.29 and 1.36 ± 0.29, respectively. The first and second attempt of SAMS showed a significant correlation with the LMII score. (R = 0.56 and R = 0.63 respectively, both showed p<0.001). Comparing the first and the second score, the latter had better for more than 90% of the participants.ConclusionSAMS showed the good correlation with LMII in older people in this community‐based study. The result that the second score of the SAMS was better and correlated better with the LMII compared to the first one suggests that it is important to provide some trial opportunities for this test administered on a tablet in order to accurately assess cognitive function in elderly subjects.

Accuracy of Electron Density Mapping of a Novel kVCBCT System Designed for Planning

A recently developed advanced kVCBCT system, designed for simulation and planning, includes improvements to the imaging panel and reconstruction technique, enabling more accurate electron density mapping than a typical CBCT. This study investigates the accuracy, limitations, and dosimetric impact of this new system. CBCT images were taken of both large (pelvis) and small (head) electron density phantoms with inserts ranging from lung (0.29) to cortical bone (1.69). Images were taken with several pre-set protocols with energies of 125 kVp and 140 kVp. The effects of longitudinal buildup (for scatter due to the cone-beam geometry) and blade position were also investigated. The HU values of each insert were measured over a small region of interest. Several electron density curves were generated - pelvis protocol on the large phantom, head protocol on the small phantom, and average - and imported into a treatment planning system. Dose calculation was performed using each curve and differences were observed. HU to electron density mapping was sensitive to the use of longitudinal buildup and blade position, with differences in the curves observed at both low and high electron densities, due to imager saturation effects not found in typical clinical scenarios. Subsequent studies used both longitudinal buildup and fully opened blades. Under these conditions, mapping was not sensitive to technique or phantom size at low electron densities. At higher values, the curves diverged, with the head protocol showing higher HU values and the pelvis protocol showing lower. The average curve matched very closely with the curve from our standard CT simulator. Dose calculation showed little dependence on the curve chosen, with max point dose differences of 1.2% between the pelvis and average scans, though most of the plan was <0.5% different. Results for the head protocol were similar. The system provides reliable HU values comparable to a CT simulator, though it is important to consider the effects of imager saturation by choosing appropriate scatter and collimation. The calibration is slightly sensitive to the choice of phantom size and beam energy, though these differences led to negligible (<0.5%) differences in dose calculation accuracy.

Early Toxicity and Patient-Reported Cosmetic Outcomes in Patients Treated With Adjuvant Proton-Based Radiotherapy After Breast-Conserving Surgery

IntroductionTo evaluate the dosimetric data, early toxicity, and patient-reported cosmetic outcomes in breast cancer patients treated with adjuvant proton-based radiotherapy (RT) after breast-conserving surgery. Materials and MethodsWe performed a retrospective review of our institutional database to identify breast cancer patients treated with breast-conserving surgery followed by proton-based RT from 2015 to 2020. Patient-reported cosmetic outcomes were graded as excellent, good, fair, or poor. Early toxicity outcomes were graded by the treating physician during treatment. Dose-volume histograms were reviewed to obtain dosimetry data. ResultsWe identified 21 patients treated with adjuvant proton-based RT. Median whole breast dose delivered was 46.8 Gy (range, 40.0-50.4 Gy). Target volumes included the regional lymph nodes in 17 patients (81%). Seventeen patients (81%) received a lumpectomy boost. The median planning target volume V95 was 94% (range, 77%-100%), V100 71% (range, 60%-97%), V110 2% (range 0%-18%), and median max point dose was 115% (range, 105%-120%). The median ipsilateral breast V105 was 367.3 cc (range, 0-1172 cc) and V110 was 24.1 cc (range, 0-321.3 cc). Grade 2 and 3 dermatitis occurred in 62% and 14% of patients, respectively. Grade 2 and 3 pain was reported by 33% and 10% of patients, respectively. Median follow-up at the time of cosmetic evaluation was 27 months (range, 5-42 months). Four patients (21%) reported fair cosmetic outcome and 15 patients (79%) reported good or excellent cosmetic outcome. No poor cosmesis was reported. ConclusionAdjuvant proton-based radiotherapy after breast-conserving surgery is well tolerated with acceptable rates of acute toxicities and a high rate of good-to-excellent patient-reported cosmetic outcomes.

External validation of pulmonary radiotherapy toxicity models for ultracentral lung tumors

IntroductionPulmonary toxicity is dose-limiting in stereotactic body radiation therapy (SBRT) for tumors that abut the proximal bronchial tree (PBT), esophagus, or other mediastinal structures. In this work we explored published models of pulmonary toxicity following SBRT for such ultracentral tumors in an independent cohort of patients. MethodsThe PubMed database was searched for pulmonary toxicity models. Identified models were tested in a cohort of patients with ultracentral lung tumors treated between 2008 and 2017 at one large center (N = 88). This cohort included 60 % primary and 40 % metastatic tumors treated to 45 Gy in 5 fractions (fx), 50 Gy in 5 fx, 60 Gy in 8 fx, or 60 Gy in 15 fx prescribed as 100 % dose to PTV. ResultsSeven published NTCP models from two studies were identified. The NTCP models utilized PBT max point dose (Dmax), D0.2 cm3, V65, V100, and V130. Within the independent cohort, the ≥ grade 3 toxicity and grade 5 toxicity rates were 18 % and 7–10 %, respectively, and the Dmax models best described pulmonary toxicity. The Dmax to 0.1 cm3 model was better calibrated and had increased steepness compared to the Dmax model. A re-planning study minimizing PBT 0.1 cm3 to below 122 Gy in EQD23 (for a 10 % ≥grade 3 pulmonary toxicity) was demonstrated to be completely feasible in 4/6 patients, and dose to PBT 0.1 cm3 was considerably lowered in all six patients. ConclusionsPulmonary toxicity models were identified from two studies and explored within an independent ultracentral lung tumor cohort. A modified Dmax to 0.1 cm3 PBT model displayed the best performance. This model could be utilized as a starting point for rationally constructed airways constraints in ultracentral patients treated with SBRT or hypofractionation.

Implementation of High-Dose-Rate, CT-Based Prostate Brachytherapy in an Academic Teaching Hospital and Residency Training Program.

IntroductionProstate brachytherapy provides the most durable local control for prostate adenocarcinoma among all radiation treatment options. However, likely due to decreased trainee familiarity with the technique and resource intensity, it has seen a decline in utilization. Here we outline our experience with starting a high-dose-rate (HDR) prostate brachytherapy program within a residency training program and present our outcome data.MethodsPatients were identified and screened using clinical data and volume study for candidacy for brachytherapy implantation. Eligible candidates were implanted and subsequently had radiation planning and delivery in our clinic. Descriptive statistical analysis was performed on our outcomes and dosimetry data and presented in tabular form.ResultsSeventeen patients were treated for a total of 18 implants (one monotherapy). No implant was aborted. No acute urinary retention requiring catheterization or chronic urethral stricture occurred. Biochemical recurrence-free survival was 94% at a median follow-up of 28.5 months (range 8.2-50 months); the one failure occurred in a very high-risk patient at 37 months following treatment. Dosimetrically, prostate coverage, urethra sparing, and rectum sparing aims were met. Volumetric bladder aims were also met; however, the max point dose to the bladder neck was above the guideline.ConclusionOur department successfully implemented an HDR prostate brachytherapy program. Treatments were effective and there was no grade 3 toxicity to report.

Radiation-induced airway changes and downstream ventilation decline in a swine model

Purpose. To investigate indirect radiation-induced changes in airways as precursors to atelectasis post radiation therapy (RT). Methods. Three Wisconsin Miniature Swine (WMS TM ) underwent a research course of 60 Gy in 5 fractions delivered to a targeted airway/vessel in the inferior left lung. The right lung received a max point dose <5 Gy. Airway segmentation was performed on the pre- and three months post-RT maximum inhale phase of the four-dimensional (4D) computed tomography (CT) scans. Changes in luminal area (Ai) and square root of wall area () for each airway were investigated. Changes in ventilation were assessed using the Jacobian ratio and were measured in three different regions: the inferior left lung <5 Gy (ILL), the superior left lung <5 Gy (SLL), and the contralateral right lung <5 Gy (RL). Results. Airways (n = 25) in the right lung for all swine showed no significant changes (p = 0.48) in Ai post-RT compared to pre-RT. Airways (n = 28) in the left lung of all swine were found to have a significant decrease (p < 0.001) in Ai post-RT compared to pre-RT, correlated (Pearson R = −0.97) with airway dose. Additionally, decreased significantly (p < 0.001) with airway dose. Lastly, the Jacobian ratio of the ILL (0.883) was lower than that of the SLL (0.932) and the RL (0.955). Conclusions. This work shows that for the swine analyzed, there were significant correlations between Ai and change with radiation dose. Additionally, there was a decrease in lung function in the regions of the lung supplied by the irradiated airways compared to the regions supplied by unirradiated airways. These results support the hypothesis that airway dose should be considered during treatment planning in order to potentially preserve functional lung and reduce lung toxicities.

Five-Year Results from a Single Institution Utilizing IORT for Early-Stage Breast Cancer in a Population Comprised of a Majority of African American Women

Intraoperative radiotherapy (IORT) for early-stage hormone receptor (HR) positive, HER2neu non-amplified breast cancer has demonstrated non-inferior rates of local control at 5 years compared with external beam radiotherapy (EBRT) based on the phase III TARGIT-A trial published in 2014. We present our 5-year institutional experience utilizing IORT since the TARGIT-A publication treating a cohort comprised primarily of African American (AA) patients, an important population whose experience with IORT is not currently well defined.Data from women with early-stage HR positive, HER2neu non-amplified breast cancer who underwent lumpectomy and immediate or delayed IORT (20 Gy prescribed to cavity surface) between 2015 and 2020 were collected on an IRB-approved study. Retrospective review of clinicodemographic variables, including age, race, body mass index (BMI), tumor pathology, and dosimetry was performed. Primary endpoints included postoperative complications, adjuvant therapies, and local recurrence rates. Statistical analyses were performed using χ2 and Student's t-tests to identify associations between categorical and continuous variables.257 patients (168 AA, 81 Caucasian, 8 other) were analyzed. Most were clinical stage IA (n = 195, 75.6%) with invasive ductal carcinoma (n = 141, 60.5%). Median age at time of IORT was 68 years (46 - 99). On average, AA women had a significantly higher BMI (32.4 vs. 28.9 kg/m2, P = 0.003) and pathologic tumor size (1.69 vs. 1.25 cm, P = 0.003) compared to Caucasian women. Caucasian women were more likely to experience a postoperative wound complication (13.6% vs. 6.0%, P = 0.04). There was one Grade 3 complication related to a surgical site infection requiring hospitalization. Max point dose to skin was not found to correlate with developing a wound complication (4.09 Gy vs. 4.06 Gy, P = 0.46). At a median follow up of 21 months there were 10 ipsilateral recurrences (3.9%, all in index quadrant) without a significant difference in frequency in IBTR between AA and Caucasian women (n = 4, 4.4% vs. n = 3.7%, P = 0.39). One patient had < 1mm DCIS margins who did not receive EBRT & two declined endocrine therapy, one of which had a focally positive margin at surgery. There were no significant differences in number of patients receiving adjuvant chemotherapy or EBRT between AA and Caucasian women (n = 24, 14.3% vs. n = 11, 13.6% P = 0.88). There was one death from metastatic breast cancer in an AA patient who declined adjuvant therapy for high-risk disease.This institutional cohort comprised predominantly of AA women showed acceptable rates of local control and no difference in IBTR rates between races. Postoperative complication rates were low (n = 21, 8.1%) with only one severe toxicity observed. Future work will examine additional clinicopathologic features and dosimetric data to assess their association with the risk of IBTR and postoperative complications.

Tangential VMAT vs. 3D-Conformal Radiotherapy for Left-Sided Whole Breast and Regional Lymph Node Irradiation

<h3>Purpose/Objective(s)</h3> Whole breast and regional nodal irradiation presents a challenge in balancing the need for target coverage with avoidance of normal tissues. The novel technique termed tangential VMAT (tVMAT) utilizes beam angles tangential to the curvature of the chest wall without beams entering perpendicular to the chest wall in the direction of thoracic organs. In this study tVMAT was compared to standard 3D-conformal radiotherapy (3DCRT) in a dosimetric analysis. To our knowledge this is the first study to assess tVMAT in left-sided breast cancer patients requiring regional nodal irradiation. <h3>Materials/Methods</h3> Ten patients with left-sided breast cancer previously treated with adjuvant RT to the breast, axillary, and supraclavicular nodal regions were selected for this study. For each patient two plans were created: 1) a standard dual-isocenter three-field 3DCRT plan (two tangents and a supraclavicular field) using field-in-field dose modulation and 2) a tVMAT plan. Each tVMAT plan utilized a single isocenter for two partial arcs with angles selected to keep the central axis of the beams tangential to the curvature of the chest wall at all points. The prescription for both techniques was 5000 cGy in 25 fractions to the breast, axillary levels I-III, and supraclavicular target volumes with a goal coverage of 95% of the breast and nodal target volumes receiving at least 95% of the prescription dose. Normal tissue dose constraints were adapted from NSABP B51. Plans were created using a treatment planning system and differences in mean values for dosimetric endpoints were assessed for statistical significance using a Student's t-test (α = 0.05). <h3>Results</h3> Compared to 3DCRT plans, tVMAT provided more uniform coverage to the breast and regional lymph nodes (mean conformity index was 1.38 for tVMAT versus 2.42 for 3DCRT, <i>P</i> < 0.01) and the max point dose for tVMAT was lower on average (112.8% for tVMAT versus 121.5% for 3DCRT, <i>P</i> < 0.001). Both plans met the breast target coverage goals, however coverage to the lymph nodes was superior for tVMAT (mean coverage to 95% of the axillary plus supraclavicular target volumes was ≥ 99.0% of the prescribed dose for tVMAT versus ≥ 94.8% for 3DCRT, <i>P</i> < 0.001). Cold spots within the breast and nodal target volumes were on average lower for 3DCRT (952 cGy for 3DCRT versus 2760 cGy for tVMAT, <i>P</i> < 0.001). OAR sparing was improved with tVMAT, with a lower average V20_Gy for the left lung (16.5% for tVMAT versus 24.6% for 3DCRT, <i>P</i> < 0.01), and lower mean heart dose (168 cGy for tVMAT versus 200 cGy for 3DCRT, <i>P</i> = 0.03). <h3>Conclusion</h3> Tangential VMAT is a promising technique for the treatment of intact breast and regional lymph nodes and may provide better target coverage and OAR sparing compared to conventional 3D-conformal techniques. The use of a single isocenter for tVMAT could yield a simplified setup and more accurate treatment delivery, ideally with the use of deep inspiration breath hold or respiratory gating.

WSe2 Homogeneous in-Plane Pin Junction Diode with Electric Double Layers

Transition metal dichalcogenide (TMDC) materials are in the spotlight as next-generation semiconductor materials because of their advantages over other semiconductor materials. Research on WSe2 among the materials is underway, and the feature of WSe2 has an ambipolar characteristic, and the fermi level change and the doping effect are different according to the electrode type.In the present study, we have fabricated a homogeneous WSe2 PIN junction diode. Our in-plane multilayer WSe2 p-i-n homogeneous diode exhibited photovoltaic properties by asymmetric physical contact doping effect with electric double layer(EDL). Owing to the EDL placed between the cathode and anode, local charge carrier type and density profile are modulated in the same layers.Compared to general diode mode, PIN mode enhance the photo response of the device in our visible measurement range. The diode exhibits excellent rectifying behavior with a current rectification ratio of 104 or higher. Photovoltaic performance of short circuit current and open circuit voltage achieved 3.2 nA, 0.55 V, respectively under the 550 nm green light. And spectrum responsivity is about ~100 mA/W (max point) at 3.2 eV to 1.6 eV. Figure 1

Optimization of the three-segment aerofoil arrangement based on wind tunnel tests and numerical analysis

This paper presents the optimization of multi-element aerofoil for the LAR-3 Puffin -- STOL light transport aircraft concept proposal. Based on the geometry and aerodynamic characteristics of the well-known and proven in flight three-segment NACA 63A416 aerofoil, the authors explore the possibility of enhancing its high-lift performance by the movement of slot and flap position in extended (deployed) aerodynamic configuration. In order to determine the optimum positions of aerofoil segments (elements), a multi-step optimization approach was developed. It combines computational fluid dynamics simulations that were used for design space screening and preliminary optimization together with low-turbulence wind tunnel tests which yielded certain results. To decrease the numerical cost of the computer simulation campaign, Design of experiment methods (optimal space-filling design among others) were employed instead of exhausting full factorial (parametric) design. Response surface models of major aerodynamic coefficients (lift, drag, pitching moment) at predicted maximum lift coefficient ( C L max) point allowed to narrow down search space and identify several candidates for optimal configuration to be checked experimentally. Wind tunnel tests campaign confirmed the major trends observed in computational fluid dynamics derived response surface contour plots. For the optimum aerodynamic configuration, chosen experimental C L max is over 3.9, which is a 10% increase over the baseline (initial slat and flap positions) case. In parallel, the maximum lift-to-drag ratio gain at that point was almost 19%. The research outlined in this paper was conducted on behalf of the aircraft production company and its results will be applied in a newly designed transport aircraft.

Abstract P4-12-20: Early toxicity and patient-reported cosmetic outcomes in patients treated with adjuvant proton-based radiotherapy after breast-conserving surgery

Abstract Background: As the number of proton centers continues to increase nationwide, the use of proton-based radiotherapy (RT) in the treatment of malignancies is expanding. Randomized trials to assess the efficacy and cardiovascular benefits of proton-based RT compared to photon-based RT in the treatment of breast cancer are underway. However, the data on early toxicity and cosmetic outcomes remains limited. In this study, we report dosimetric data, early toxicity, and patient-reported cosmetic outcomes in breast cancer patients treated with adjuvant proton-based RT after breast-conserving surgery. Methods: We performed a retrospective review of our institutional database to identify breast cancer patients treated with breast-conserving surgery followed by proton-based RT from 2015 to 2019. Patient-reported cosmetic outcomes were graded as excellent, good, fair, and poor. Early toxicity outcomes were graded by the treating physician during the treatment course using the National Cancer Institute Common Terminology Criteria for Adverse Events (CTCAE), version 3.0. Dose-volume histograms (DVHs) were reviewed to obtain dosimetry data. Results: We identified 21 patients treated with adjuvant proton-based RT. Median age at diagnosis was 58 (range, 26-85). Median body mass index was 26.1 (range, 19.8-58.3). Three patients (14%) had a history of diabetes and three patients (14%) smoking. Three patients (14%) had a history of ipsilateral breast cancer treated with adjuvant RT, and one patient had a history of ipsilateral lung cancer treated with definitive RT. Eleven patients had T1 primary tumors (52%), fifteen (71%) were node-positive, and twelve (57%) had left-sided tumors. Twelve patients (57%) received neoadjuvant and five patients (24%) adjuvant chemotherapy. Median whole breast dose delivered was 46.8Gy (range, 40.0-50.4Gy). Target volumes included the regional lymph nodes in seventeen patients (81%). Seventeen patients (81%) received a lumpectomy boost with a median dose of 10Gy (range, 10-14Gy). The median planning target volume V95 was 94% (range, 77-100%), V100 71% (range, 60-97%), V110 2% (range 0-18%), and median max point dose was 115% (range, 105-120%). The median ipsilateral breast V105 was 367.3cc (range, 0-1172cc) and V110 was 24.1cc (range, 0-321.3cc). Median mean heart dose was 0.39Gy (range, 0-2.6Gy). Median ipsilateral lung V20 was 10% (range, 0-28%) and ipsilateral lung V5 was 28.5% (range, 0.8-55.7%). CTCAE grade 2 dermatitis occurred in 62% and grade 3 in 14% of patients. Grade 2 pain was reported by 33% and grade 3 by 10% of patients. Grade 2 fatigue was reported by 33% of patients. One patient developed acute esophagitis. Median follow-up at the time of cosmetic evaluation was 27 months (range, 5-42 months). Two patients died before cosmetic evaluation. Four patients (21%) reported fair cosmetic outcome and 15 patients (79%) reported good or excellent cosmetic outcome. No poor cosmesis was reported. Conclusions: Adjuvant proton-based radiotherapy after breast-conserving surgery results in low normal tissue exposure compared to typical photon-based plans, particularly when the regional lymphatics are targeted. Proton-based RT is well tolerated with acceptable rates of acute toxicities and a high rate of good-to-excellent patient-reported cosmetic outcomes. Citation Format: Mutlay Sayan, Yin Zhang, Bo Liu, Apar Gupta, Bruce Haffty, Nisha Ohri. Early toxicity and patient-reported cosmetic outcomes in patients treated with adjuvant proton-based radiotherapy after breast-conserving surgery [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P4-12-20.

Late Toxicity and Cosmesis in Women Receiving Hypofractionated Radiotherapy after Breast-Conserving Therapy and Oncoplastic Reconstruction

Hypofractionated (HF) radiotherapy (RT) is now recommended for the majority of women undergoing breast conserving surgery (BCS). Oncoplastic reconstruction (OR) combines BCS with plastic surgery techniques to allow for oncologic resection while preserving cosmesis. Cosmesis and toxicity for OR with conventionally fractionated (CF) RT is well established. While HFRT is now standard of care, there are limited data reporting cosmesis for women undergoing HFRT after OR. Given OR is a cosmetic procedure, this study aimed to demonstrate acceptable late toxicity and post-treatment cosmesis with HFRT after BCS and OP. Women with > 3 months of follow-up after treatment with BCS, OR and HFRT between 2010 and 2018 were identified. Surgery was performed either as a single or staged procedure with immediate or delayed reconstruction. All women received 42.56 Gy to the whole breast using field-in-field technique. A lumpectomy cavity boost was performed at the discretion of the treating physician. Demographic, disease and treatment characteristics, and toxicity outcomes were recorded. For a subset of patients, pre and post-operative photos were maintained. Cosmesis at the time of most recent follow-up was independently rated by two plastic surgeons and two radiation oncologists (excellent, good, fair, poor). Chi-squared, Mann-Whitney U, and logistic regression were used to assess association between patient/treatment related factors and toxicity. 38 women were identified with a median follow-up of 12 months from completion of HFRT. Median age was 61.5 (61% white, 30% black, and 9% mixed /other). 55% underwent a single procedure with immediate reconstruction. 61% had local tissue rearrangement alone, 20% had mastopexy and reduction, and 24% had flap rearrangement. 16% of women received a lumpectomy cavity boost. Due to inability to accurately delineate the post-surgical tumor bed, the lumpectomy cavity was only contoured in 66% of women. Surgical toxicities were reported in 12% women prior to HFRT. Late cosmesis related toxicities were found in 52% women (table 1) of which the majority (58%) were skin toxicity (all RTOG grade 1). There was no significant association between age, race, BMI, comorbidities, receptor status, chemotherapy status, HFRT treatment position, boost, V105, or max point dose and late cosmesis. Of the cohort with longitudinal photos, cosmesis was rated as excellent in 42%, good in 46%, and fair in 12%. There were no locoregional failures. OR with HFRT has good toxicity profiles and favorable physician rated cosmetic outcomes. It offers an acceptable alternative to CFRT. Further investigation of patient reported cosmesis and prospective evaluation of OR and HFRT is warranted.Abstract 2113; Table 1Late Toxicityn (%)Pain3 (7)Edema4 (12)Fibrosis2 (5)Dimpling0 (0)Nipple retraction2 (5)Volume loss1 (2)Skin changes11 (29) Open table in a new tab

Analisis Pengaruh Holding Time terhadap Sifat Mekanis dan Struktur Mikro pada Proses Induction Tempering Batang Piston Baja SCM 420 H

Selection of materials connecting rod for a component or structure usually involves several aspects, there are aspects of specific strength, stiffness, lightweight, noncorrosive materials and resistance or age. In the manufacturing process connecting rod always give heat treatment such as Normalizing, Carburizing, and Induction Tempering. In the process, Induction Tempering has a big problem in hardness after the process, not stable and liable to over from standard. Process condition of tempering induction temperature in 650~700 C at 1 atm pressure, & holding time variation at 5, 10, 15, and 20 seconds. Kind of tests such as bending test, magna-flux, hardness, and structure micro. Bending test report fiber flow is straight, not broke because not found micro crack portension at body connecting rod. Hardness test result min point 23 HRC and max point 39,2 HRC base on standard range 25~44 HRC. The results of surface morphological observation show that the martensite phase causes hardness value to increase.

Temporal Lobe Radiation Necrosis after Proton Re-irradiation Therapy Involving the Skull Base

To analyze clinical and dosimetric factors for the occurrence of temporal lobe necrosis (TLN) among patients who received proton re-irradiation therapy involving the skull base. We analyzed 99 consecutive patients who received proton re-irradiation involving the skull base between 09/2013 and 03/2017. Follow up interval was defined from the beginning of proton therapy. Analyzed factors included gender, history of hypertension and/or diabetes, smoking status, prior radiation dose, composite dose to 2cc and composite max pixel dose to the temporal lobe. Outcomes of interest included the grade of TLN, incidence as well as time to development of TLN among patients treated in the re-irradiation setting. Median doses were compared using the Mann-Whitney’s test. Univariate and multivariate Cox regression analysis were performed. Of the 99 patients, 86 (87%) were treated for recurrent locoregional disease and 12 (12%) for metastatic disease. The median follow up was 12 months (IQR 6-21) for the entire cohort and 17 months (IQR 9-26) for living patients; median survival at 1 year was 64.5%. The most common primary sites were the nasopharynx (n=22) and paranasal cavity/sinuses (n=18) and the most common histologies included squamous cell carcinoma (n=51) and adenoid cystic carcinoma (n=12). The median first course radiation dose to the skull base was 6360cGy for those without TLN and 7020cGy for those with TLN (p=0.02). Median re-irradiation proton dose was 60CGE without TLN and 70CGE with TLN (p=0.18). The average interval between first and second course treatment was 25 months. 15 (15%) developed temporal lobe necrosis within a median time of 19 months (IQR 15-30): 9 had right-sided, 5 had left-sided, and 1 had bilateral TLN. The median composite max point dose was 63.7Gy among patients without TLN and 120Gy for those with TLN (p<0.001). The median composite dose to 2cc was 73.1Gy among patients without TLN and 134.5Gy with TLN (p<0.001). On multivariate Cox regression, male gender (HR 8.47, p=0.008), hypertension (HR 4.78, p=0.017) and higher composite max point dose (HR 1.03, p=0.011) were significantly associated with development of TLN. All patients were determined to have grade 1 TLN per CTCAE 4.0 that was found on imaging and were clinically asymptomatic except for two patients. Both required medical management with steroids. Among patients treated in the re-irradiation setting with proton therapy, 15% of patients developed TLN, which is comparable to TLN rates in the upfront setting with IMRT. The rate of grade 3 TLN was 1% and there was no grade 4 TLN. No TLN was observed in patients with a composite temporal lobe D2cc under 60Gy, or with a composite max point dose under 72Gy.

Updated Retrospective Dose Volume Histogram Analysis of High Dose Rate Prostate Brachytherapy Patients With Hydrogel Spacer Implantation

A commercially available bioabsorbable hydrogel system—a mixture of a precursor (trilysine buffer solution and polyethylene glycol powder) and accelerator (salt buffer)—is implanted between the prostate and rectum of men undergoing radiation therapy for prostate cancer. Use of this device provides additional separation between the prostate and rectum, ostensibly reducing rectal injury due to proximity of the high dose target. This study investigates rectal sparing achieved in high dose rate (HDR) prostate brachytherapy patients with hydrogel spacer implantation. One hundred and fifty two monotherapy HDR prostate brachytherapy cases were selected from the patient population treated from July 2015 to February 13, 2017. Patients were selected based on a treatment regimen of 13.5 Gy per fraction. Of these cases, 120 fractions were delivered to patients with implanted hydrogel rectal spacers while 32 fractions were treated without the use of this or any other rectal sparing device. For this patient cohort, the dose volume histogram (DVH) from the previously calculated plan was used to obtain D1cc, D2cc, and maximum rectal dose statistics based on rectum contours drawn on the planning CT dataset by the dosimetrist at the time of treatment planning. To compare to conventionally fractionated external beam radiation therapy (EBRT), the equivalent dose in 2 Gy fractions (EQD2) was calculated for each rectal dose statistic. Statistical analysis software was employed for data analysis. The D1cc, D2cc, and maximum dose to the rectum for cases in which the hydrogel spacer was implanted prior to treatment were compared to cases treated without rectal sparing devices. Results with and without hydrogel spacer implantation were as follows: D1cc was 7.9±0.2 Gy and 8.4±0.4 Gy, respectively; D2cc was 7.1±0.2 Gy and 7.5±0.4 Gy, respectively; and the maximum dose to the rectum as 10.7±0.3 Gy and 11.9±0.6 Gy, respectively. Reduction in maximum (p < 0.001) and small volumetric doses (p = 0.027 and 0.113 for D1cc and D2cc) to the rectum is observed in cases implementing the hydrogel rectal spacer. Considering a typical HDR prostate brachytherapy dose prescription of 27.0 Gy (two 13.5 Gy fractions) and an α/β = 3.0 for rectum, the average maximum EQD2 point dose for patients receiving hydrogel implants was 59.9±3.1 Gy compared to 71.9±2.8 Gy (p < 0.001) for those treated without the device. DVH analysis for the patient sampling with hydrogel implantation demonstrated statistically significant reduction in Dmax and D1cc metrics. When compared to plans without hydrogel implants, the average EQD2 of the max point dose to rectum for patients receiving hydrogel implants was lower and fell within the TD5/5 of 60 Gy, as recommended by Emami et al. Future clinical evaluation of these patients may allow for a statistical relationship between the observed dose reduction and clinical toxicity.

SU‐F‐T‐624: Dose Sparing to Normal Brain Tissue for Stereotactic Radiosurgery Utilizing Negative Margins

Purpose:The volume of normal brain tissue exposed to doses above 12 Gy (V12) strongly predicts the risk of radionecrosis. A negative margin MLC aperture results in fields smaller than the PTV. The aim of this study is to investigate the relationship between V12 and the negative margin MLC while keeping adequate PTV coverage with proper dose normalization.Methods:Spherical PTVs were contoured with a center of mass in the frontal and left temporal lobe ranging in size from 1 cm to 4 cm in diameter. A field arrangement was determined for each PTV location using five dynamic conformal arcs for the frontal PTV and three dynamic conformal arcs for the left temporal PTV. Treatment plans for each PTV were generated using a MLC aperture with a positive margin of 1 mm and dose normalized so that the prescribed 18 Gy covers 95% of the PTV. New plans were generated with MLC aperture margins reduced in 1 mm increments, until the max point dose reached is greater than 200%. The volume of dose outside the PTV to 12, 9 and 5 Gy was analyzed.Results:Depending on the PTV size, the greatest negative margin planned was between −4 mm and −2 mm. Negative margins of −1 mm yielded the lowest significant volumes to all doses. Reductions in V12 in relation to the PTV volumes were between 15% and 31% for PTV sizes of 4 and 1 cm, when compared to the 1 mm positive margin plan.Conclusion:Doses to normal tissue were reduced most with margins of −1 and −2 mm for all PTV sizes. In general the −2 mm margin was minimally superior, so a −1 mm margin can be followed in most circumstances to limit maximum PTV dose.

Experimental research of particle size and size dispersity on the explosibility characteristics of coal dust

In the present research work, the effects of particle size (D50) and size dispersity (σD) on the explosion severity of coal dust were investigated using a 20L spherical explosion vessel. Coal dust samples with similar median diameter (D50) and different size dispersity (σD) and similar size dispersity (σD) and different size diameter (D50) were specially prepared by mixing original coal samples having a narrow size distribution. The explosion severity of each sample was evaluated by measuring the maximum pressure (Pmax) and the maximum rate of pressure rise ((dP/dt)max). Interestingly, results show that almost all of the selected coal dusts present the same optimum explosion concentration of 250g/m3. The parameters of Pmax and (dP/dt)max show an increasing trend in explosion severity as size dispersity (σD) and particle size (D50) decrease, which indicate a more notable effect due to the contribution of finer coal particles on the dust cloud deflagration dynamics. The higher the volatile matter content, the more severe is the explosion. The presence of the finer particles would greatly increase the total effective specific surface area and speed up the devolatilization rate, which would cause acceleration of the dust explosion process. Furthermore, the effects of dust concentration on the explosion process were analyzed by comparing the defined time span (τ1) from ignition point to reach (dP/dt)max point and time span (τ2) from (dP/dt)max point to reach Pmax point. For the coal dust with lower D50 and lower σD, τ1 and τ2 are always short. Under lower coal dust concentration condition (<250g/m3), τ1 and τ2 present a stronger dependence on σD and dust concentration. However, the effect of σD and dust concentration on τ1 and τ2 becomes weak for the higher coal dust clouds (>250g/m3). Results indicated that the evaluation of coal dust explosion hazard should be considered in terms of not only dust concentration, but also particle size (D50) and size dispersity (σD).

A Bottom-Up Whole-Body Physiologically Based Pharmacokinetic Model to Mechanistically Predict Tissue Distribution and the Rate of Subcutaneous Absorption of Therapeutic Proteins.

The ability to predict subcutaneous (SC) absorption rate and tissue distribution of therapeutic proteins (TPs) using a bottom-up approach is highly desirable early in the drug development process prior to clinical data being available. A whole-body physiologically based pharmacokinetic (PBPK) model, requiring only a few drug parameters, to predict plasma and interstitial fluid concentrations of TPs in humans after intravenous and subcutaneous dosing has been developed. Movement of TPs between vascular and interstitial spaces was described by considering both convection and diffusion processes using a 2-pore framework. The model was optimised using a variety of literature sources, such as tissue lymph/plasma concentration ratios in humans and animals, information on the percentage of dose absorbed following SC dosing via lymph in animals and data showing loss of radiolabelled IgG from the SC dosing site in humans. The resultant model was used to predict t max and plasma concentration profiles for 12 TPs (molecular weight 8–150 kDa) following SC dosing. The predicted plasma concentration profiles were generally comparable to observed data. t max was predicted within 3-fold of reported values, with one third of the predictions within 0.8–1.25-fold. There was no systematic bias in simulated C max values, although a general trend for underprediction of t max was observed. No clear trend between prediction accuracy of t max and TP isoelectric point or molecular size was apparent. The mechanistic whole-body PBPK model described here can be applied to predict absorption rate of TPs into blood and movement into target tissues following SC dosing.Electronic supplementary materialThe online version of this article (doi:10.1208/s12248-015-9819-4) contains supplementary material, which is available to authorized users.

SU‐E‐J‐32: Dosimetric Evaluation Based On Pre‐Treatment Cone Beam CT for Spine Stereotactic Body Radiotherapy: Does Region of Interest Focus Matter?

Purpose:Spine stereotactic body radiotherapy requires very conformal dose distributions and precise delivery. Prior to treatment, a KV cone‐beam CT (KV‐CBCT) is registered to the planning CT to provide image‐guided positional corrections, which depend on selection of the region of interest (ROI) because of imperfect patient positioning and anatomical deformation. Our objective is to determine the dosimetric impact of ROI selections.Methods:Twelve patients were selected for this study with the treatment regions varied from C‐spine to T‐spine. For each patient, the KV‐CBCT was registered to the planning CT three times using distinct ROIs: one encompassing the entire patient, a large ROI containing large bony anatomy, and a small target‐focused ROI. Each registered CBCT volume, saved as an aligned dataset, was then sent to the planning system. The treated plan was applied to each dataset and dose was recalculated. The tumor dose coverage (percentage of target volume receiving prescription dose), maximum point dose to 0.03 cc of the spinal cord, and dose to 10% of the spinal cord volume (V10) for each alignment were compared to the original plan.Results:The average magnitude of tumor coverage deviation was 3.9%±5.8% with external contour, 1.5%±1.1% with large ROI, 1.3%±1.1% with small ROI. Spinal cord V10 deviation from plan was 6.6%±6.6% with external contour, 3.5%±3.1% with large ROI, and 1.2%±1.0% with small ROI. Spinal cord max point dose deviation from plan was: 12.2%±13.3% with external contour, 8.5%±8.4% with large ROI, and 3.7%±2.8% with small ROI.Conclusion:A small ROI focused on the target results in the smallest deviation from planned dose to target and cord although rotations at large distances from the targets were observed. It is recommended that image fusion during CBCT focus narrowly on the target volume to minimize dosimetric error. Improvement in patient setups may further reduce residual errors.

SO-04 * INTERNATIONAL CONSENSUS GUIDELINES FOR POST-OPERATIVE STEREOTACTIC BODY RADIATION THERAPY (SBRT) FOR MALIGNANT SPINE TUMORS

Emerging data suggests that post-operative SBRT for malignant spinal tumors may improve local control compared to conventional radiation therapy. However, few guidelines exist. The purpose of this study was to develop consensus guidelines to guide safe, effective treatment. Twenty spine specialists representing 19 centers in 4 countries with a collective experience of >1300 cases completed survey. Responses were defined as follows: 1) consensus: selected by ≥75%, 2) predominant: selected by ≥50%, 3) controversial: no single response selected by a majority of respondents. Consensus indications include: radio-resistant primary, 1-2 levels of adjacent disease and/or prior RT to same site. Contra-indications include: >3 contiguous vertebral bodies involved, ASIA score A (complete spinal cord injury without preservation of motor or sensory function), post-operative Bilsky grade 3 residual (cord compression without any CSF around the cord). For treatment planning, predominance of physicians co-register pre-operative MRI and post-operative T1 post-gadolinium MRI and delineate cord on T2 variant MRI or CT myelogram in cases of significant hardware artifact. Consensus GTV is post-operative residual tumor based on MRI. CTV is predominantly post-operative bed defined as entire extent of pre-operative tumor & anatomic compartment plus residual disease. Consensus is that hardware and scar do not need to be included. PTV expansion is controversial (range: 0-2 mm). Predominant prescription dose for initial treatment is 18 Gy x 1 with max point to cord <12-14 Gy (prescription range: 16-48.5 Gy in 1-10 fractions). For re-treatment, physicians predominantly account for repair and time interval between prior RT and spinal SBRT in calculating cord constraints. Acceptable PTV coverage is controversial, but physicians predominantly compromise coverage to meet cord constraint and/or fractionate to improve coverage while meeting cord constraint. Future investigation will be critical in better understanding areas of controversy including circumferential treatment of epidural space, margin for paraspinal extension and optimal dose/fractionation.