Medicine and Health Sciences Commons^™

Fast Generation Of Lung Sbrt Plans With A Knowledge-Based Planning Model On Ring-Mounted Halcyon Linac, Justin Visak, Aaron Webster, Mark E. Bernard, Mahesh R. Kudrimoti, Marcus E. Randall, Ronald C. Mcgarry, Damodar Pokhrel

Radiation Medicine Faculty Publications

PURPOSE: To demonstrate fast treatment planning feasibility of stereotactic body radiation therapy (SBRT) for centrally located lung tumors on Halcyon Linac via a previously validated knowledge-based planning (KBP) model to support offline adaptive radiotherapy.

MATERIALS/METHODS: Twenty previously treated non-coplanar volumetric-modulated arc therapy (VMAT) lung SBRT plans (c-Truebeam) on SBRT-dedicated C-arm Truebeam Linac were selected. Patients received 50 Gy in five fractions. c-Truebeam plans were re-optimized for Halcyon manually (m-Halcyon) and with KBP model (k-Halcyon). Both m-Halcyon and k-Halcyon plans were normalized for identical or better target coverage than clinical c-Truebeam …

Predicting The Effect Of Indirect Cell Kill In The Treatment Of Multiple Brain Metastases Via Single-Isocenter/Multitarget Volumetric Modulated Arc Therapy Stereotactic Radiosurgery, Allison N. Palmiero, Denise Fabian, Marcus E. Randall, William St. Clair, Damodar Pokhrel

Radiation Medicine Faculty Publications

PURPOSE: Due to spatial uncertainty, patient setup errors are of major concern for radiosurgery of multiple brain metastases (m-bm) when using single-isocenter/multitarget (SIMT) volumetric modulated arc therapy (VMAT) techniques. However, recent clinical outcome studies show high rates of tumor local control for SIMT-VMAT. In addition to direct cell kill (DCK), another possible explanation includes the effects of indirect cell kill (ICK) via devascularization for a single dose of 15 Gy or more and by inducing a radiation immune intratumor response. This study quantifies the role of indirect cell death in dosimetric errors as a function of spatial patient setup uncertainty …

Computer Automation For Physics Chart Check Should Be Adopted In Clinic To Replace Manual Chart Checking For Radiotherapy, Edward L. Clouser, Quan Chen, Yi Rong

Radiation Medicine Faculty Publications

No abstract provided.

An Analytical Expression For R50% Dependent On Ptv Surface Area And Volume: A Cranial Srs Comparison, Dharmin D. Desai, Ellis Lee Johnson, Ivan L. Cordrey

Radiation Medicine Faculty Publications

The intermediate dose spill for a stereotactic radiosurgery (SRS) plan can be quantified with the metric R50%, defined as the 50% isodose cloud volume (V_IDC50%) divided by the volume of the planning target volume (PTV). By coupling sound physical principles with the basic definition of R50%, we derive an analytical expression for R50% for a spherical PTV. Our analytical expression depends on three quantities: the surface area of PTV (SA_PTV), the volume of PTV (V_PTV), and the distance of dose drop-off to 50% (Δr). The value of ∆r was obtained from a simple set …

A Novel And Clinically Useful Dynamic Conformal Arc (Dca)-Based Vmat Planning Technique For Lung Sbrt, Damodar Pokhrel, Justin Visak, Lana Sanford

Radiation Medicine Faculty Publications

PURPOSE: Volumetric modulated arc therapy (VMAT) is gaining popularity for stereotactic treatment of lung lesions for medically inoperable patients. Due to multiple beamlets in delivery of highly modulated VMAT plans, there are dose delivery uncertainties associated with small-field dosimetry error and interplay effects with small lesions. We describe and compare a clinically useful dynamic conformal arc (DCA)-based VMAT (d-VMAT) technique for lung SBRT using flattening filter free (FFF) beams to minimize these effects.

MATERIALS AND METHODS: Ten solitary early-stage I-II non-small-cell lung cancer (NSCLC) patients were treated with a single dose of 30 Gy using 3-6 non-coplanar VMAT arcs (clinical …

Evaluation Of Plan Quality And Treatment Efficiency For Single-Isocenter/Two-Lesion Lung Stereotactic Body Radiation Therapy, Lana Sanford, Janelle A. Molloy, Sameera S. Kumar, Marcus Randall, Ronald C. Mcgarry, Damodar Pokhrel

Radiation Medicine Faculty Publications

Purpose/objectives: To evaluate the plan quality and treatment delivery efficiency of single‐isocenter/two‐lesions volumetric modulated arc therapy (VMAT) lung stereotactic body radiation therapy (SBRT).

Materials/methods: Eight consecutive patients with two peripherally located early stage nonsmall‐cell‐lung cancer (NSCLC) lung lesions underwent single‐isocenter highly conformal noncoplanar VMAT SBRT treatment in our institution. A single‐isocenter was placed between the two lesions. Doses were 54 or 50 Gy in 3 and 5 fractions respectively. Patients were treated every other day. Plans were calculated in Eclipse with AcurosXB algorithm and normalized to at least 95% of the planning target volume (PTV) receiving 100% of the prescribed …

Randomized Phase Ii Study Comparing Prophylactic Cranial Irradiation Alone To Prophylactic Cranial Irradiation And Consolidative Extracranial Irradiation For Extensive-Disease Small Cell Lung Cancer (Ed Sclc): Nrg Oncology Rtog 0937, Elizabeth M. Gore, Chen Hu, Alexander Y. Sun, Daniel F. Grimm, Suresh S. Ramalingam, Neal E. Dunlap, Kristin A. Higgins, Maria Werner-Wasik, Aaron M. Allen, Puneeth Iyengar, Gregory M. M. Videtic, Russell K. Hales, Ronald C. Mcgarry, James J. Urbanic, Anthony T. Pu, Candice A. Johnstone, Volker W. Stieber, Rebecca Paulus, Jeffrey D. Bradley

Radiation Medicine Faculty Publications

Introduction—RTOG-0937 is a randomized phase-II trial evaluating 1-year OS with PCI or PCI plus consolidative radiation therapy (cRT) to intra-thoracic disease and extracranial metastases for ED-SCLC.

Methods—Patients with 1–4 extracranial metastases were eligible after CR or PR to chemotherapy. Randomization was to PCI or PCI+cRT to the thorax and metastases. Original stratification included PR vs CR after chemotherapy and 1 vs 2–4 metastases; age < 65 vs ≥ 65 was added after an observed imbalance. PCI was 25GY/10 fractions. cRT was 45GY/15 fractions. To detect an OS improvement from 30% to 45% with a 34% hazard reduction (HR=0·66) under a 0.1 type-1 error (1-sided) and 80% power, 154 patients were required.

Results—Ninety-seven patients were randomized between March, 2010 and February, 2015. Eleven patients were ineligible (nine PCI, two PCI+cRT), leaving 42 randomized to PCI and 44 to PCI+cRT. At planned interim analysis the study …

A Naturally Generated Decoy Of The Prostate Apoptosis Response-4 Protein Overcomes Therapy Resistance In Tumors, Nikhil Hebbar, Ravshan Burikhanov, Nidhi Shukla, Shirley Qiu, Yanming Zhao, Kojo S. J. Elenitoba-Johnson, Vivek M. Rangnekar

Radiation Medicine Faculty Publications

Primary tumors are often heterogeneous, composed of therapy-sensitive and emerging therapy-resistant cancer cells. Interestingly, treatment of therapy-sensitive tumors in heterogeneous tumor microenvironments results in apoptosis of therapy-resistant tumors. In this study, we identify a prostate apoptosis response-4 (Par-4) amino-terminal fragment (PAF) that is released by diverse therapy-sensitive cancer cells following therapy-induced caspase cleavage of the tumor suppressor Par-4 protein. PAF caused apoptosis in cancer cells resistant to therapy and inhibited tumor growth. A VASA segment of Par-4 mediated its binding and degradation by the ubiquitin ligase Fbxo45, resulting in loss of Par-4 proapoptotic function. Conversely, PAF, which contains this VASA …