Cost-Effectiveness of Primary Radiation Therapy Versus Radical Prostatectomy for Intermediate- to High-Risk Prostate Cancer

PURPOSE

To compare, using a cost-effectiveness analysis, the quality-adjusted life expectancy (QALE) and cost between the 2 treatment options for intermediate- to high-risk prostate cancer: (1) radiation (RT) with androgen deprivation therapy (ADT) or (2) radical prostatectomy (RP) followed by adjuvant RT for patients with risk factors.

METHODS AND MATERIALS

Our Markov model allowed patients to transition between health states with yearly probabilities of developing cancer recurrence and/or toxicity. Probabilities were assigned according to favorable intermediate, unfavorable intermediate, or high-risk prostate cancer groups. The primary analysis examined outcomes for patients aged 65 years, whereas secondary analyses explored the effects of younger age, elevated baseline cardiovascular risk, and the use of salvage therapy. One-way and probabilistic sensitivity analyses were performed.

RESULTS

Across all primary and secondary analyses, and using a wide-range of assumptions, RT + ADT was the preferred treatment strategy for men with intermediate- to high-risk prostate cancer. The QALE was higher after RT + ADT by 0.5 to 1.14 quality-adjusted life years, compared with RP. Radiation plus ADT was cost-effective in all situations, falling beneath a threshold of $100,000 per quality-adjusted life year. Among all risk groups, a greater proportion of patients undergoing RP experienced single or multiple treatment toxicities.

CONCLUSIONS

Radiation plus ADT may result in improved QALE compared with RP for intermediate- to high-risk prostate cancer. Although biochemical failure is similar between treatment groups, there is a higher rate of developing multiple toxicities among patients treated with upfront RP.

A nomogram for testosterone recovery following combined androgen deprivation therapy and radiation therapy for prostate cancer

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Background: Combined androgen deprivation therapy (ADT) and radiation therapy (RT) is a frequently used localized prostate cancer (PC) treatment. Testosterone recovery (TR) after combined ADT-RT is not well-characterized. We studied TR in men who received RT and either short-term (ST) ADT or long-term (LT) ADT with LHRH agonists. Methods: We identified consecutive localized PC patients treated with ADT-RT at the Durham VA Medical Center (DVAMC) from 1/2011-10/2016. All patients had a documented baseline testosterone (T) level. Individual patient records were reviewed. TR was defined as time from last ADT injection to T normalization ( > 240 ng/dL). The Kaplan-Meier method was used to estimate time to TR. Cox proportional hazards models were generated to identify TR predictors with a nomogram built based on a parsimonious multivariate model. Results: 252 patients were identified. Median follow-up was 26.7 months. Median age was 65. Prior to treatment, 69% had a normal baseline T. 67% were treated with STADT, median duration 6 months. 33% were treated with LTADT, median duration 18 months. Median time for TR was 22.6 months for all patients (19.5 months for STADT and 25.6 months for LTADT). At 1 and 2 years post ADT, estimated TR was 13% and 53% (17% and 57% for STADT and 3% and 42% for LTADT). 2-year biochemical control was 99.2% and 97.6% for STADT and LTADT, respectively; 98.9% and 98.6% for those with and without TR, respectively. On multivariate analysis, higher pre-treatment T (HR = 1.004 95% CI 1.003-1.006, p < 0.001), use of STADT (HR = 2.48 95% CI 1.45-4.25, p = 0.001), and lower BMI (HR = 0.95 95% CI 0.91-0.98, p = 0.001) were associated with shorter time to TR. White race was a negative TR predictor (HR = 0.65 95% CI 0.43-0.9992, p = 0.049). Age, smoking, and Charlson Comorbidity Index were not significant independent TR predictors. A nomogram was generated to predict probability of TR at 1, 2, and 3 years. Conclusions: In this VA population of localized PC patients treated from 2011-2016, TR following the use of ADT-RT was variable. Using pre-treatment T levels, ADT duration, BMI, and race, a predictive nomogram can estimate the likelihood of TR.

Prostate cancer specific mortality and overall survival outcomes for salvage radiation therapy after radical prostatectomy

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Background: Early salvage radiation therapy (SRT) following radical prostatectomy (RP) has been shown to reduce biochemical recurrence and distant metastases. We aim to identify factors predictive of prostate cancer-specific mortality (PCSM) and all-cause mortality (ACM) from a consortium database from 10 academic institutions. Methods: 2,454 node-negative patients (pts) with detectable post-prostatectomy PSA ( ≥ 0.01 ng/mL) treated with SRT ± neoadjuvant/concurrent androgen deprivation therapy (N/C ADT) were included. Cumulative incidence and Kaplan-Meier methods were used to estimate rates of PCSM and ACM, respectively. Univariate and multivariable analyses (MVA) were performed by competing risks regression and Cox proportional hazards methods for PCSM and ACM. Results: Median follow-up was 5 years from SRT completion and 8 years from date of RP; 24% had pathologic Gleason score (GS) of ≤ 6, 56% GS 7, and 19% GS ≥ 8; 56% extraprostatic extension (EPE), 18% seminal vesicle invasion (SVI), 58% positive surgical margins, and 16% received N/C ADT. Median age at RP and SRT were 62 years (IQR 56-66) and 64 years (59-69), respectively. Median SRT dose was 66 Gy (IQR 65-68) and median pre-SRT PSA was 0.5 ng/mL (IQR 0.3-1.1). MVA performed from SRT completion date demonstrated higher pre-SRT PSA (HR = 2.1), higher GS (GS 7 vs. ≤ 6: HR 2.0; GS ≥ 8 vs. 6: HR 3.3) , SVI (HR 2.5), year of SRT (2000-2004, 1995-1999, 1985-1994 vs. 2005-2012; HR 2.9, HR 2.5, HR 3.6, respectively) were significantly associated with higher PCSM. These same variables were all significantly associated with higher PCSM and ACM rates calculated from both SRT completion date and date of RP. Conclusions: Initiation of early SRT at lower post-operative PSA levels following RP is associated with reduced risk of PCSM and ACM, even when calculated from RP date to account for lead time bias. Other factors significantly associated with PCSM include higher GS, SVI, and earlier year of SRT. [Table: see text]

Toxicity and quality of life report of a phase II study of stereotactic body radiotherapy (SBRT) for low and intermediate risk prostate cancer

BACKGROUND

Clinical data indicates that delivery of larger daily doses of radiation may improve the therapeutic ratio for prostate cancer compared to conventional fractionation. A phase II study of stereotactic body radiotherapy with real-time motion management and daily plan re-optimization for low to intermediate risk prostate cancer was undertaken to evaluate this hypothesis. This report details the toxicity and quality of life following treatment.

METHODS

From 2009 to 2013, 60 patients with T1-T2c prostate cancer with a Gleason score of 6 and PSA ≤ 15 or Gleason score of 7 and PSA ≤ 10 were enrolled. Patients with nodal metastases, an American Urological Association symptom score > 18, or gland size > 100 g were not eligible. Patients were treated to 37 Gy in 5 fractions. Early and late genitourinary and gastrointestinal toxicity were graded based on NCI CTCAE v4.0 and quality of life was assessed by the American Urological Association symptom score, International Index of Erectile Function, and Expanded Prostate cancer Index Composite Short Form up to 36 months after treatment.

RESULTS

After a median follow-up of 27.6 months, no grade 3 or greater genitourinary toxicity was observed. Four patients (6.7%) reported a late grade 2 genitourinary toxicity. One patient (1.7%) reported a late grade 3 gastrointestinal toxicity. Five patients (8.3%) developed a late grade 2 gastrointestinal toxicity. The median American Urological Association symptom score increased from 4.5 prior to treatment to 11 while on treatment (p < 0.01), but was 5 at 36 months post-treatment (p = 0.65). Median International Index of Erectile Function scores decreased from 19 to 17 over the course of follow-up (p < 0.01). Only median scores within the Expanded Prostate Cancer Index Composite Short Form sexual domain were significantly decreased at 36 months post-treatment (67.9 vs 45.2, p = 0.02). There was no significant difference in median score within the urinary, bowel, or hormonal domains at 36 months of follow-up.

CONCLUSIONS

Stereotactic body radiotherapy for low to intermediate risk prostate cancer is well tolerated with limited toxicity or decrease in quality of life. Longer follow-up is necessary to assess the efficacy of treatment.

TRIAL REGISTRATION

Clinicaltrials.gov NCT00941915 Registered 17 June 2009.

Contemporary Update of a Multi-Institutional Predictive Nomogram for Salvage Radiotherapy After Radical Prostatectomy

PURPOSE

We aimed to update a previously published, multi-institutional nomogram of outcomes for salvage radiotherapy (SRT) following radical prostatectomy (RP) for prostate cancer, including patients treated in the contemporary era.

METHODS

Individual data from node-negative patients with a detectable post-RP prostate-specific antigen (PSA) treated with SRT with or without concurrent androgen-deprivation therapy (ADT) were obtained from 10 academic institutions. Freedom from biochemical failure (FFBF) and distant metastases (DM) rates were estimated, and predictive nomograms were generated.

RESULTS

Overall, 2,460 patients with a median follow-up of 5 years were included; 599 patients (24%) had a Gleason score (GS) ≤ 6, 1,387 (56%) had a GS of 7, 244 (10%) had a GS of 8, and 230 (9%) had a GS of 9 to 10. There were 1,370 patients (56%) with extraprostatic extension (EPE), 452 (18%) with seminal vesicle invasion (SVI), 1,434 (58%) with positive surgical margins, and 390 (16%) who received ADT (median, 6 months). The median pre-SRT PSA was 0.5 ng/mL (interquartile range, 0.3 to 1.1). The 5-yr FFBF rate was 56% overall, 71% for those with a pre-SRT PSA level of 0.01 to 0.2 ng/mL (n = 441), 63% for those with a PSA of 0.21 to 0.50 ng/mL (n = 822), 54% for those with a PSA of 0.51 to 1.0 ng/mL (n = 533), 43% for those with a PSA of 1.01 to 2.0 ng/mL (n = 341), and 37% for those with a PSA > 2.0 ng/mL (n = 323); P < .001. On multivariable analysis, pre-SRT PSA, GS, EPE, SVI, surgical margins, ADT use, and SRT dose were associated with FFBF. Pre-SRT PSA, GS, SVI, surgical margins, and ADT use were associated with DM, whereas EPE and SRT dose were not. The nomogram concordance indices were 0.68 (FFBF) and 0.74 (DM).

CONCLUSION

Early SRT at low PSA levels after RP is associated with improved FFBF and DM rates. Contemporary nomograms can estimate individual patient outcomes after SRT in the modern era.

Developing Teaching Strategies in the EHR Era: A Survey of GME Experts

BACKGROUND

There is limited information on the impact of widespread adoption of the electronic health record (EHR) on graduate medical education (GME).

OBJECTIVE

To identify areas of consensus by education experts, where the use of EHR impacts GME, with the goal of developing strategies and tools to enhance GME teaching and learning in the EHR environment.

METHODS

Information was solicited from experienced US physician educators who use EPIC EHR following 3 steps: 2 rounds of online surveys using the Delphi technique, followed by telephone interviews. The survey contained 3 stem questions and 52 items with Likert-scale responses. Consensus was defined by predetermined cutoffs. A second survey reassessed items for which consensus was not initially achieved. Common themes to improve GME in settings with an EHR were compiled from the telephone interviews.

RESULTS

The panel included 19 physicians in 15 states in Round 1, 12 in Round 2, and 10 for the interviews. Ten items were found important for teaching and learning: balancing focus on EHR documentation with patient engagement achieved 100% consensus. Other items achieving consensus included adequate learning time, balancing EHR data with verbal history and physical examination, communicating clinical thought processes, hands-on EHR practice, minimizing data repetition, and development of shortcuts and templates. Teaching strategies incorporating both online software and face-to-face solutions were identified during the interviews.

CONCLUSIONS

New strategies are needed for effective teaching and learning of residents and fellows, capitalizing on the potential of the EHR, while minimizing any unintended negative impact on medical education.

Randomized Phase III Noninferiority Study Comparing Two Radiotherapy Fractionation Schedules in Patients With Low-Risk Prostate Cancer

PURPOSE

Conventional radiotherapy (C-RT) treatment schedules for patients with prostate cancer typically require 40 to 45 treatments that take place from > 8 to 9 weeks. Preclinical and clinical research suggest that hypofractionation-fewer treatments but at a higher dose per treatment-may produce similar outcomes. This trial was designed to assess whether the efficacy of a hypofractionated radiotherapy (H-RT) treatment schedule is no worse than a C-RT schedule in men with low-risk prostate cancer.

PATIENTS AND METHODS

A total of 1,115 men with low-risk prostate cancer were randomly assigned 1:1 to C-RT (73.8 Gy in 41 fractions over 8.2 weeks) or to H-RT (70 Gy in 28 fractions over 5.6 weeks). This trial was designed to establish (with 90% power and an α of .05) that treatment with H-RT results in 5-year disease-free survival (DFS) that is not worse than C-RT by more than 7.65% (H-RT/C-RT hazard ratio [HR] < 1.52).

RESULTS

A total of 1,092 men were protocol eligible and had follow-up information; 542 patients were assigned to C-RT and 550 to H-RT. Median follow-up was 5.8 years. Baseline characteristics were not different according to treatment assignment. The estimated 5-year DFS was 85.3% (95% CI, 81.9 to 88.1) in the C-RT arm and 86.3% (95% CI, 83.1 to 89.0) in the H-RT arm. The DFS HR was 0.85 (95% CI, 0.64 to 1.14), and the predefined noninferiority criterion that required that DFS outcomes be consistent with HR < 1.52 was met (P < .001). Late grade 2 and 3 GI and genitourinary adverse events were increased (HR, 1.31 to 1.59) in patients who were treated with H-RT.

CONCLUSION

In men with low-risk prostate cancer, the efficacy of 70 Gy in 28 fractions over 5.6 weeks is not inferior to 73.8 Gy in 41 fractions over 8.2 weeks, although an increase in late GI/genitourinary adverse events was observed in patients treated with H-RT.

Abstract S3-04: ESR1 coregulator binding inhibitor (ECBI) as a novel therapeutic to target hormone therapy resistant metastatic breast cancer

BACKGROUND: Estrogen contribute to the progression of breast cancer via estrogen receptor 1 (ESR1) and current therapies involve either antiestrogens or aromatase inhibitors. However, most patients develop resistance to these drugs. Critically, therapy-resistant tumors retain ESR1-signaling. Mechanisms of therapy resistance involve the activation of ESR1 in the absence of ligand or mutations in ESR1 that allow interaction between the ESR1 and coregulators leading to sustained ESR1 signaling and proliferation. For patients with therapy-resistant breast cancers, there is a critical unmet need for novel agents to disrupt ESR1 signaling by blocking ESR1 interactions with its coregulators.

METHODS: Using rational design, we synthesized and evaluated a small organic molecule (ESR1 coregulator binding inhibitor, ECBI) that mimics the ESR1 coregulator nuclear receptor box motif. Using in vitro cell proliferation and apoptosis assays, we tested the effect of ECBI on several breast cancer and therapy-resistant model cells. Mechanistic studies were conducted using established biochemical assays, reporter gene assays, RT-qPCR and RNA-Seq analysis. Differentially expressed genes were analyzed using Ingenuity Pathway Analysis (IPA). ESR1 positive (MCF7 and ZR75) xenografts were used for preclinical evaluation and toxicity. The efficacy of ECBI was tested using ex vivo cultures of freshly extirpated primary human breast tissues.

RESULTS: In estrogen induced proliferation assays using several ESR1 positive model cells, ECBI significantly inhibited growth and promoted apoptosis. Importantly, ECBI showed little or no activity on ESR1 negative cells. Further, ECBI also reduced the proliferation of several ESR1 positive hormonal therapy resistant cells. Mechanistic studies showed that ECBI interacts with ESR1, efficiently blocks ESR1 interactions with coregulators and reduces the ESR1 driven ERE reporter gene activity. Further, ECBI directly interacted with mutant-ESR1 with high affinity and significantly inhibited mutant-ESR1 driven oncogenic activity. RNA sequencing analysis revealed that ECBI blocks multiple ESR1 driven pathways, likely representing the ability of a single ECBI compound to block multiple ESR1-coregulator interactions. Treatment of ESR1-positive xenograft tumors with ECBI (10 mg/kg/day/oral) significantly reduced the tumor volume compared to control. Further, ECBI also significantly reduced the tumor growth of coregulator-overexpressed breast cancer cells in xenograft model. Using human primary breast tissue ex vivo cultures, we have provided evidence that ECBI has potential to dramatically reduce proliferation of human breast tumors.

CONCLUSIONS: The ECBI is a novel agent that targets ESR1 with a unique mechanism of action. ECBI has distinct pharmacologic advantages of oral bioavailability, in vivo stability, and is associated with minimal systemic side effects. Remarkably, ECBI block both native and mutant forms of ESR1 and have activity against therapy resistant breast cancer cell proliferation both in vitro and in vivo and against primary human tumor tissues ex vivo. Thus development of ECBI represents a quantum leap in therapies to target ESR1.

Citation Format: Vadlamudi RK, Sareddy GR, Viswanadhapalli S, Lee T-K, Ma S-H, Lee WR, Mann M, Krishnan SR, Gonugunta V, Strand DW, Tekmal RR, Ahn J-M, Raj GV. ESR1 coregulator binding inhibitor (ECBI) as a novel therapeutic to target hormone therapy resistant metastatic breast cancer. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr S3-04.

Therapeutic targeting of tetraspanin8 in epithelial ovarian cancer invasion and metastasis

Epithelial ovarian cancer (EOC) invasion and metastasis are complex phenomena that result from the coordinated action of many metastatic regulators and must be overcome to improve clinical outcomes for patients with these cancers. The identification of novel therapeutic targets is critical because of the limited success of current treatment regimens, particularly in advanced-stage ovarian cancers. In this study, we found that tetraspanin 8 (TSPAN8) is overexpressed in about 52% (14/27) of EOC tissues and correlates with poor survival. Using small interfering RNA-mediated TSPAN8 knockdown and a competition assay with purified TSPAN8 large extracellular loop (TSPAN8-LEL) protein, we identified TSPAN8-LEL as a key regulator of EOC cell invasion. Furthermore, monotherapy with TSPAN8-blocking antibody we developed shows that antibody-based modulation of TSPAN8-LEL can significantly reduce the incidence of EOC metastasis without severe toxicity in vivo. Finally, we demonstrated that the TSPAN8-blocking antibody promotes the internalization and concomitant downregulation of cell surface TSPAN8. Collectively, our data suggest TSPAN8 as a potential novel therapeutic target in EOCs and antibody targeting of TSPAN8 as an effective strategy for inhibiting invasion and metastasis of TSPAN8-expressing EOCs.

NRG Oncology RTOG 0415: A randomized phase III non-inferiority study comparing two fractionation schedules in patients with low-risk prostate cancer

1

Background: To determine whether the efficacy of a hypofractionated (H) schedule is no worse than a conventional (C) schedule in men with low-risk prostate cancer. Methods: From April 2006 to December 2009, one thousand one hundred fifteen men with low-risk prostate cancer (clinical stage T1-2a, Gleason ≤ 6, PSA < 10) were randomly assigned 1:1 to a conventional (C) schedule (73.8 Gy in 41 fractions over 8.2 weeks) or to a hypofractionated (H) schedule (70 Gy in 28 fractions over 5.6 weeks). The trial was designed to establish with 90% power and alpha = 0.05 that (H) results in 5-year disease-free survival (DFS) that is not lower than (C) by more than 7% (hazard ratio (HR) < 1.52). Secondary endpoints include freedom from biochemical recurrence (FFBR) and overall survival. At the third planned interim analysis (July 2015), the NRG Oncology Data Monitoring Committee recommended that the results of the trial be reported. Results: One thousand one hundred and one protocol eligible men were randomized: 547 to C and 554 to H. Median follow-up is 5.9 years. Baseline characteristics are not different according to treatment arm. At the time of analysis 185 DFS events have been observed; 99 in the C arm and 86 in the H arm. The estimated 7-year disease-free survival is 75.6% (95% CI 70.3, 80.1) in the C arm and 81.8% (77.5, 85.3) in the H arm. The DFS HR (C/H) is 0.85 (0.64, 1.14). Comparison of biochemical recurrence (HR = 0.77, (0.51, 1.17)) and overall survival (HR = 0.95, (0.65, 1.41)) also met protocol non-inferiority criteria. Grade ≥ 3 GI toxicity is 3.0% (C) vs. 4.6% (H), Relative risk (RR) for H vs. C 1.53, (95% CI 0.86, 2.83); grade ≥ 3 GU toxicity is 4.5% (C) vs. 6.4% (H), RR = 1.43 (0.86,2.37). Conclusions: In men with low-risk prostate cancer, 70 Gy in 28 fractions over 5.6 weeks is non-inferior to 73.8 Gy in 41 fractions over 8.2 weeks. Clinical trial information: NCT00331773.

Atlas-guided prostate intensity modulated radiation therapy (IMRT) planning

An atlas-based IMRT planning technique for prostate cancer was developed and evaluated. A multi-dose atlas was built based on the anatomy patterns of the patients, more specifically, the percent distance to the prostate and the concaveness angle formed by the seminal vesicles relative to the anterior-posterior axis. A 70-case dataset was classified using a k-medoids clustering analysis to recognize anatomy pattern variations in the dataset. The best classification, defined by the number of classes or medoids, was determined by the largest value of the average silhouette width. Reference plans from each class formed a multi-dose atlas. The atlas-guided planning (AGP) technique started with matching the new case anatomy pattern to one of the reference cases in the atlas; then a deformable registration between the atlas and new case anatomies transferred the dose from the atlas to the new case to guide inverse planning with full automation. 20 additional clinical cases were re-planned to evaluate the AGP technique. Dosimetric properties between AGP and clinical plans were evaluated. The classification analysis determined that the 5-case atlas would best represent anatomy patterns for the patient cohort. AGP took approximately 1 min on average (corresponding to 70 iterations of optimization) for all cases. When dosimetric parameters were compared, the differences between AGP and clinical plans were less than 3.5%, albeit some statistical significances observed: homogeneity index (p  >  0.05), conformity index (p  <  0.01), bladder gEUD (p  <  0.01), and rectum gEUD (p  =  0.02). Atlas-guided treatment planning is feasible and efficient. Atlas predicted dose can effectively guide the optimizer to achieve plan quality comparable to that of clinical plans.

Longitudinal Trends in Costs of Palliative Radiation for Metastatic Prostate Cancer

BACKGROUND

In recent years, palliative treatment of prostate cancer metastases has been characterized by the use of more complex radiation treatment, despite a lack of evidence demonstrating a clinical benefit of these technologies in the palliative setting. The impact of adoption of these technologies on the costs of palliative radiation treatment in patients with metastatic prostate cancer remains poorly understood in the general patient population.

METHODS

The study was a retrospective analysis of Surveillance, Epidemiology and End Results (SEER) Medicare data of men aged 66 and older who died from metastatic prostate cancer between 2000 and 2007 and received radiation therapy for bony metastases in the last year of life. Direct costs were obtained from Medicare carrier and outpatient facility payments for all radiation treatment claims and adjusted to 2008 dollars.

RESULTS

A total of 1705 men met study inclusion criteria. Total Medicare payments for radiation therapy for bony metastases in the last year of life increased by 44.4% from an average of $2,763 in 2000 to $3,989 in 2007, with the proportion of all payments accrued within hospital-based settings increasing from 48% to 57%. Complexity of radiation therapy techniques over the same period was characterized by use of less simple (30.1% to 23.3%) and more complex (59.9% versus 66.7%) radiation therapy. From 2000-2003 to 2004-2007, the use of shorter treatment courses (≤5 fractions) decreased from 22% to 14%, and the use of single fraction treatment courses decreased by half (6.3% to 2.9%; P≤.001).

CONCLUSIONS

Between 2000 and 2007, palliative radiation therapy for bony prostate cancer metastases was characterized by the use of more advanced treatment technologies and prolonged radiation treatment courses. Further research investigating barriers to cost-effective palliation is warranted.

Quantitative comparison of automatic and manual IMRT optimization for prostate cancer: the benefits of DVH prediction

A recent publication indicated that the patient anatomical feature (PAF) model was capable of predicting optimal objectives based on past experience. In this study, the benefits of IMRT optimization using PAF-predicted objectives as guidance for prostate were evaluated. Three different optimization methods were compared.1) Expert Plan: Ten prostate cases (16 plans) were planned by an expert planner using conventional trial-and-error approach started with institutional modified OAR and PTV constraints. Optimization was stopped at 150 iterations and that plan was saved as Expert Plan. 2) Clinical Plan: The planner would keep working on the Expert Plan till he was satisfied with the dosimetric quality and the final plan was referred to as Clinical Plan. 3) PAF Plan: A third sets of plans for the same ten patients were generated fully automatically using predicted DVHs as guidance. The optimization was based on PAF-based predicted objectives, and was continued to 150 iterations without human interaction. DMAX and D98% for PTV, DMAX for femoral heads, DMAX, D10cc, D25%/D17%, and D40% for bladder/rectum were compared. Clinical Plans are further optimized with more iterations and adjustments, but in general provided limited dosimetric benefits over Expert Plans. PTV D98% agreed within 2.31% among Expert, Clinical, and PAF plans. Between Clinical and PAF Plans, differences for DMAX of PTV, bladder, and rectum were within 2.65%, 2.46%, and 2.20%, respectively. Bladder D10cc was higher for PAF but < 1.54% in general. Bladder D25% and D40% were lower for PAF, by up to 7.71% and 6.81%, respectively. Rectum D10cc, D17%, and D40% were 2.11%, 2.72%, and 0.27% lower for PAF, respectively. DMAX for femoral heads were comparable (< 35 Gy on average). Compared to Clinical Plan (Primary + Boost), the average optimization time for PAF plan was reduced by 5.2 min on average, with a maximum reduction of 7.1min. Total numbers of MUs per plan for PAF Plans were lower than Clinical Plans, indicating better delivery efficiency. The PAF-guided planning process is capable of generating clinical-quality prostate IMRT plans with no human intervention. Compared to manual optimization, this automatic optimization increases planning and delivery efficiency, while maintainingplan quality.

Edge profile measurements using Thomson scattering on the KSTAR tokamak

In the KSTAR Tokamak, a "Tangential Thomson Scattering" (TTS) diagnostic system has been designed and installed to measure electron density and temperature profiles. In the edge system, TTS has 12 optical fiber bundles to measure the edge profiles with 10-15 mm spatial resolution. These 12 optical fibers and their spatial resolution are not enough to measure the pedestal width with a high accuracy but allow observations of L-H transition or H-L transitions at the edge. For these measurements, the prototype ITER edge Thomson Nd:YAG laser system manufactured by JAEA in Japan is installed. In this paper, the KSTAR TTS system is briefly described and some TTS edge profiles are presented and compared against the KSTAR Charge Exchange Spectroscopy and other diagnostics. The future upgrade plan of the system is also discussed in this paper.