Adam P Dicker

Publications (174) View all

• Article: Implementation and experimental results of 4D tumor tracking using robotic couch.

  I Buzurovic, Y Yu, M Werner-Wasik, T Biswas, P R Anne, A P Dicker, T K Podder
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  ABSTRACT: Purpose: This study presents the implementation and experimental results of a novel technique for 4D tumor tracking using a commercially available and commonly used treatment couch and evaluates the tumor tracking accuracy in clinical settings.Methods: Commercially available couch is capable of positioning the patient accurately; however, currently there is no provision for compensating physiological movement using the treatment couch in real-time. In this paper, a real-time couch tracking control technique is presented together with experimental results in tumor motion compensation in four dimensions (superior-inferior, lateral, anterior-posterior, and time). To implement real-time couch motion for tracking, a novel control system for the treatment couch was developed. The primary functional requirements for this novel technique were: (a) the treatment couch should maintain all previous∕normal features for patient setup and positioning, (b) the new control system should be used as a parallel system when tumor tracking would be deployed, and (c) tracking could be performed in a single direction and∕or concurrently in all three directions of the couch motion (longitudinal, lateral, and vertical). To the authors' best knowledge, the implementation of such technique to a regular treatment couch for tumor tracking has not been reported so far. To evaluate the performance of the tracking couch, we investigated the mechanical characteristics of the system such as system positioning resolution, repeatability, accuracy, and tracking performance. Performance of the tracking system was evaluated using dosimetric test as an endpoint. To investigate the accuracy of real-time tracking in the clinical setting, the existing clinical treatment couch was replaced with our experimental couch and the linear accelerator was used to deliver 3D conformal radiation therapy (3D-CRT) and intensity modulated radiation therapy (IMRT) treatment plans with and without tracking. The results of radiation dose distribution from these two sets of experiments were compared and presented here.Results: The mechanical accuracies were 0.12, 0.14, and 0.18 mm in X, Y, and Z directions. The repeatability of the desired motion was within ±0.2 mm. The differences of central axis dose between the 3D-CRT stationary plan and two tracking plans with different motion trajectories were 0.21% and 1.19%. The absolute dose differences of both 3D tracking plans comparing to the stationary plan were 1.09% and 1.20%. Comparing the stationary IMRT plan with the tracking IMRT plan, it was observed that the central axis dose difference was -0.87% and the absolute difference of both IMRT plans was 0.55%.Conclusions: The experimental results revealed that the treatment couch could be successfully used for real-time tumor tracking with a high level of accuracy. It was demonstrated that 4D tumor tracking was feasible using existing couch with implementation of appropriate tracking methodology and with modifications in the control system.
  Medical Physics 11/2012; 39(11):6957-67. · 2.83 Impact Factor
• Article: Costs of early adjuvant radiation therapy after radical prostatectomy: a decision analysis.

  T N Showalter, K A Foley, E Jutkowitz, C D Lallas, E J Trabulsi, L G Gomella, A P Dicker, L T Pizzi
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  ABSTRACT: This analysis was carried out to evaluate the cost-effectiveness of adjuvant radiation therapy (ART) versus observation, using a decision analysis model based primarily upon the published results of the Southwest Oncology Group prospective trial (SWOG 8794). A decision analysis model was designed to compare ART versus observation over a 10-year time horizon. Probabilities of treatment success, utilization of salvage treatments, and rates of adverse events were taken from published results of SWOG 8794. Cost inputs were based on 2010 Medicare reimbursement rates. Primary outcome measure was incremental cost per prostate-specific antigen (PSA) success (i.e. serum PSA level <0.4 ng/ml). ART results in a higher PSA success rate than observation with probability of 0.43 versus 0.22. The mean incremental cost per patient for ART versus observation was $6023. The mean incremental cost-effectiveness ratio was $26,983 over the 10-year period. ART appears cost effective compared with observation based upon this decision analysis model. Future research should consider more costly radiation therapy (RT) approaches, such as intensity-modulated RT, and should evaluate the cost-effectiveness of ART versus early salvage RT.
  Annals of Oncology 06/2011; 23(3):701-6. · 6.43 Impact Factor
• Source

  Available from: Yaacov Richard Lawrence

  Article: Early toxicity predicts long-term survival in high-grade glioma.

  Y R Lawrence, M Wang, A P Dicker, D Andrews, W J Curran, J M Michalski, L Souhami, W-Ka Yung, M Mehta
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  ABSTRACT: Patients with high-grade gliomas are treated with surgery followed by chemoradiation. The risk factors and implications of neurological side effects are not known. Acute and late ≥ grade 3 neurological toxicities (NTs) were analysed among 2761 patients from 14 RTOG trials accrued from 1983 to 2003. The association between acute and late toxicity was analysed using a stepwise logistic regression model. The association between the occurrence of acute NT and survival was analysed as an independent variable. There were 2610 analysable patients (86% glioblastoma, 10% anaplastic astrocytoma). All received a systemic agent during radiation (83% chemotherapy, 17% biological agents). Median radiation dose was 60 Gy. There were 182 acute and 83 late NT events. On univariate analysis, older age, poor performance status, aggressive surgery, pre-existing neurological dysfunction, poor mental status and twice-daily radiation were associated with increased acute NT. In a stepwise logistic regression model the occurrence of acute NT was significantly associated with late NT (OR=2.40; 95% CI=1.2-4.8; P=0.014). The occurrence of acute NT predicted poorer overall survival, independent of recursive partitioning analysis class (median 7.8 vs 11.8 months). Acute NT is significantly associated with both late NT and overall survival.
  British Journal of Cancer 04/2011; 104(9):1365-71. · 5.04 Impact Factor
• Article: Zebrafish: an emerging model system for human disease and drug discovery.

  G Kari, U Rodeck, A P Dicker
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  ABSTRACT: In vivo studies represent an essential step in drug development and currently rely largely on mice, yet limitations of mammalian models motivated the search for complementary vertebrate model systems. This review focuses on zebrafish, Danio rerio, as a facile model system to study human disease and drug responses. Zebrafish are particularly suited for this purpose because they represent a vertebrate species, their genome is sequenced, and a large number of synchronously developing, transparent embryos can be produced. Zebrafish embryos are permeable to drugs and can easily be manipulated using well-established genetic and molecular approaches. Here, we summarize recent work on drug discovery and toxicity in zebrafish embryos. In addition, we provide a synopsis of current efforts to establish disease models in zebrafish focusing on neoplasia. The results of these studies highlight the potential of zebrafish as a viable addition to established animal models by offering medium and, potentially, high throughput capabilities.
  Clinical Pharmacology &#38 Therapeutics 08/2007; 82(1):70-80. · 6.04 Impact Factor
• Article: E-mail and oncology: a survey of radiation oncology patients and their attitudes to a new generation of health communication.

  C Katzen, M J Solan, A P Dicker
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  ABSTRACT: Electronic mail (e-mail) is a powerful tool that can greatly enhance communication and has numerous potential applications within the medical profession. Physician-patient e-mail communication volume is increasing, but little research has addressed patient interests and concerns about this now commonplace technology. The goals of this study were to review the available literature regarding physician-patient e-mail practices, evaluate patient interest, assess patient perspectives about how e-mail communication might facilitate medical treatment and advice, and determine areas of patient concern regarding e-mail communication with their physicians. To this end, a population of cancer patients was sent a written survey designed to assess their access to e-mail and attitudes about physician-patient e-mail communication. We found that patients favored e-mail for increased convenience, efficiency, and timeliness about general health problems, while it was not favored for urgent matters.
  Prostate Cancer and Prostatic Diseases 02/2005; 8(2):189-93. · 2.42 Impact Factor