Radiation Medicine Commons^™

Mechanistic Insights Into The Flash Effect: The Role Of Oxygen And Radiation Chemistry In Ultra-High Dose Rate Radiation Therapy, Jacob Pierce Sunnerberg

Dartmouth College Ph.D Dissertations

The development of new cancer therapies focuses on widening the therapeutic ratio between tumor control and normal tissue toxicity. Over the last decade, ultra-high dose rate (UHDR) radiation therapy, commonly known as FLASH radiotherapy (FLASH-RT), has shown promising potential to reduce normal tissue toxicity while maintaining tumor control. However, the underlying mechanisms of the FLASH effect remain poorly understood. This thesis explores the radiation-chemical basis of FLASH-RT, focusing on the role of oxygen and reactive oxygen species in modulating biological outcomes.

A comprehensive set of in vitro studies demonstrated that UHDR delivery significantly alters radiation chemistry compared to conventional dose …

Developing Radiosensitizers To Enhance Radiotherapy In Treating Gastroenteropancreatic Neuroendocrine Tumor, Zeta Chow

Theses and Dissertations--Clinical and Translational Science

Gastroenteropancreatic Neuroendocrine Tumor (GEP-NET) is a heterogeneous group of malignancies arising from multipotent neuroendocrine stem cells in the gastrointestinal tract. The incidence of GEP-NET continues to rise, possibly due to the advancement of imaging and biomarkers available for diagnosis. However, even though the majority of patients are diagnosed with low-grade and localized disease, a significant percentage of patients present with advanced-stage metastatic disease with poor prognosis in months to a few years. These advanced-stage GEP-NET patients can also present with a variety of debilitating symptoms that significantly impact their quality of life. The role of palliative-intent surgery is limited, and …

Investigate The Delivery Efficiency Improvement For Sparc Compared To Impt, Peilin Liu, B A. De Jong, S Chang, Lewei Zhao, G Liu, Craig Stevens, Rohan Deraniyagala, E W. Korevaar, J A. Langendijk, Xiaoqiang Li, Xuanfeng Ding

Conference Presentation Abstracts

Purpose: To assess the efficiency improvement of SPArc compared to IMPT in proton clinical operation.Methods: A random clinical operation day at a proton therapy center with a two room system. Aa total of 10 Head & Neck cancer cases treated on Jan 6th, 2021were selected and SPArc plans were generated for all the cases with similar target coverage and dose constraints of organ at risk (OARs). 3% range uncertainties and 3mm setup uncertainties were applied for robust optimization. The log files of clinical IMPT were exported to calculate true treatment delivery time. The machine-specific delivery sequence model was utilized to …

A Comprehensive Investigation Of Linear Energy Transfer Optimization Effectiveness In Intensity-Modulated Proton Therapy Via Alternating Direction Method Of Multipliers (Impt Let-Admm), Q Fan, G Liu, Lewei Zhao, Xiaoqiang Li, Xuanfeng Ding, S Dai

Conference Presentation Abstracts

Linear energy transfer (LET)-guided optimization in intensity-modulated proton therapy (IMPT) via alternating direction method of multipliers (ADMM) has the potential to improve its biological effectiveness (IMPTLET- ADMM), in which the LET distribution in target can be escalated, while the LET distribution in the organs at risk can be mitigated. This study aims to quantitatively investigate the effectiveness of LET optimization in IMPT via ADMM with different solvers in its iteration loop. Methods: The clinical dose-volume-histogram (DVH) constraint noted dose sub-problem and clinical LET -volume-histogram (LVH) constraint noted LET sub-problem are combined to generate a composite objective function, which is available …

Particle Arc Single-Isocenter Stereotactic Radiosurgery Of Multiple Brain Metastases, L Volz, S Mein, T Tessonnier, Peilin Liu, A Mairani, M Durante, Xuanfeng Ding, C Graeff, T Li

Conference Presentation Abstracts

Purpose: To develop spot-scanning proton (SPArc) and heavy ion (SHArc) arc therapy for single-isocenter stereotatic radiosurgery (SISRS) of multiple brain metastases (MBMs). First results achieved with dedicated planning infrastructure are compared to state-of-the -art volumetric modulated photon arc therapy (HA-VMAT). Methods: A multi-institutional collaboration was established to develop bespoke SPArc and SHArc SISRS infrastructure with available research and commercial treatment planning systems. Devised planning and delivery methods considered dedicated energy, spot, and multi-arc selection strategies. SPArc and SHArc (carbon and helium ions) plans were generated for MBM patients exhibiting 3-12 intracranial lesions with GTV volumes between 0.03ccm and 19.8ccm, at …

Does Proton Arc Therapy Has Potential Clinical Benefits For Hepatocellular Carcinoma?, Peilin Liu, R Dalfsen, M Soukup, Shupeng Chen, Lewei Zhao, Z Wang, X S. Gao, Thomas Quinn, Craig Stevens, Rohan Deraniyagala, Xiaoqiang Li, Xuanfeng Ding

Conference Presentation Abstracts

Purpose: To investigate the potential clinical benefits and dose-averaged Linear Energy Transfer (LETd) sparing, utilizing proton arc plan for Hepatocellular carcinoma (HCC) patients in comparison with Intensity Modulated Proton Therapy (IMPT). Methods: Ten HCC patients have been retrospectively selected. Two planning groups were created: Proton Arc plans using Monaco ver. 6 and the clinical IMPT plan. Both planning groups used the same robustness parameters. The prescription dose is 67.5 Gy (RBE) in 15 fractions/ 66 GyE in 10 fractions of the Clinical Target Volume (CTV) following clinical IMPT plan. Robustness evaluations were performed to ensure target dose coverage. Normal Tissue …

An Analytic Model Of The External Beam Dose Rate Effect On Immune Cells In Blood Dosimetry, Lewei Zhao, Peilin Liu, G Liu, Xuanfeng Ding

Conference Presentation Abstracts

Purpose: Radiation therapy is a double-edged sword with regard to its immunomodulatory effect. It is critical to find how it is affected by dose rate. Thus, we developed an analytic model for calculating the number of immune cells receiving radiation. Methods: Suppose the blood is received radiation by constant dose rate. The blood is one-way flow without circulation in the radiation delivery at a constant velocity. Two kinds of lung treatment regimens were considered standard delivery 2Gy per fx total 30fx and hypo-fractionation SBRT 12 Gy per fx total 5 fx. Two different dose rates were simulated for standard treatment: …

Expansion Of The Detrusor Muscular Ring Surrounding The Bladder Neck On Mri: Moving Beyond The Prostate As An Etiology Of Lower Urinary Tract Symptoms Due To Benign Prostatic Hyperplasia, Kiran Nandalur, David Walker, Hong Ye, Sayf A. Al-Katib, Brian Seifman, David Gangwish, Abhay Dhaliwal, Connor Ervin, Kayla Dobies, Channing Sesoko, Sirisha Nandalur, Bernadette Zwaans, Jennifer Nguyen, Jason Hafron

Conference Presentation Abstracts

Purpose: The etiology of lower urinary tract symptoms secondary to benign prostatic hyperplasia (LUTS/BPH) remains uncertain. The purpose of our study was to quantitatively analyze pelvic anatomic characteristics on magnetic resonance imaging (MRI) to assess for independent factors for symptoms.
*Methods and Materials: This retrospective single-institution study evaluated treatment-naïve men who underwent prostate MRI within 3 months of International Prostate Symptom Score (IPSS) from June 2021 to February 2022. Factors measured on MRI included: detrusor muscular ring surrounding the bladder neck measured as area and alternatively diameter, central gland (CG) mean apparent diffusion coefficient (ADC), levator hiatus (LH) volume, intrapelvic …

The Contribution Of Patient Reported Outcome Measures To Shared Decision-Making In Radiation Oncology At A Midwestern Comprehensive Cancer Center, Kellie Bodeker

Doctor of Philosophy in Translational Health Sciences Dissertations

Background. Chronic diseases, such as lung cancer, require a provider-patient relationship developed over time. This relationship fosters shared decision-making (SDM), a collaborative, dynamic information exchange and analysis between provider and patient regarding treatment and desired outcomes. Established benefits to SDM include an improved quality of life and decreased anxiety and depression. Despite established benefits, recent research suggests radiation oncologists are not engaging in SDM. A decision-aid tool utilizing patient reported outcome measures may increase SDM between radiation oncologists and patients with lung cancer. Patient-reported outcome measures, wherein the patient provides direct assessment of their health and quality of life, …

External Beam Radiation Therapy Carries Lower Risk Of Sexual Dysfunction As Compared To Radical Prostatectomy In Treatment Of Patients With Localized Prostate Cancer, Aamod S. Dekhne

Clinical Research in Practice: The Journal of Team Hippocrates

A clinical decision report appraising:

Donovan JL, Hamdy FC, Lane JA, et al. Patient-Reported Outcomes after Monitoring, Surgery, or Radiotherapy for Prostate Cancer. N Engl J Med. 2016;375(15):1425-1437. https://doi.org/10.1056/NEJMoa1606221

for a patient with localized prostate cancer and concerns regarding future sexual dysfunction.

Development Of Fully Balanced Ssfp And Computer Vision Applications For Mri-Assisted Radiosurgery (Mars), Jeremiah Sanders

Dissertations and Theses (Open Access)

Prostate cancer is the second most common cancer in men and the second-leading cause of cancer death in men. Brachytherapy is a highly effective treatment option for prostate cancer, and is the most cost-effective initial treatment among all other therapeutic options for low to intermediate risk patients of prostate cancer. In low-dose-rate (LDR) brachytherapy, verifying the location of the radioactive seeds within the prostate and in relation to critical normal structures after seed implantation is essential to ensuring positive treatment outcomes.

One current gap in knowledge is how to simultaneously image the prostate, surrounding anatomy, and radioactive seeds within the …