Funding Sources

National Institute of Health (NIH)

NCI P01 CA241508           Investigating Patient,Tumor,and Treatment Factors Underlying Sensitivity of Cancers and Normal Tissues to Proton vs. Photon Radiation

The overall goals are (a) understanding relative clinical, biological and immuno-suppressive determinants of response to proton vs. photon therapy; (b) developing personalized response predictive models based on such determinants; and (c) applying individualized (as opposed to population-based) approaches for the selection of the optimum radiation modality for each patient and to enhance the therapeutic potential with IMRT and IMPT dose distributions tailored to an individual patient’s baseline and tumor characteristics. These goals will be achieved in three synergistic projects. Project 1: Understanding Normal Tissue Toxicity to Identify Patients Most Likely to Benefit from Proton vs. Photon Therapy; Project 2: Radiation-Induced Lymphopenia: Understanding, Predictive Modeling and Developing Photon and Proton-Based Mitigation Strategies; and Project 3: Investigating Enhanced Sensitivity of Tumors to Proton Beam Therapy: Mechanisms and Biomarkers.  The projects are highly integrated in that treatment modality selection and dose distribution optimization to maximally enhance the therapeutic ratio must consider and balance normal tissue complications (Project 1), radiation-induced immuno-suppression (Project 2)  and tumor response based on genotypic factors (Project 3), which cannot be accomplished by any one project alone.

NCI R01 CA229178          Fast Individualized Delivery Adaptation in Proton Therapy

While adaptive therapy has been studied before, none of the previous studies deals with the unique challenges (range uncertainties) and unique capabilities (beamlet optimization and prompt gamma imaging) of proton therapy. This proposal will for the first time address these aspects by developing innovative hardware and software methodologies. We envision treatment planning and delivery to be fully adaptive in terms of intra- fractional changes in patient geometry. This proposal aims at predicting the dose distribution (or a surrogate thereof) in the patient immediately prior to treatment delivery and correct for any discrepancies between the measured and intended dose in less than 2 minutes. This will enable us to deliver (proton) radiation therapy in an adaptive setting and much reduced target volume margins (2mm isotropic plus 2mm range margin in proton therapy in the beam direction) daily while the patient is positioned on the treatment table. We propose to achieve this goal by simultaneously developing fast hardware and software tools that take advantage of in-room prompt gamma and cone-beam CT imaging in combination with fast dose calculation. We will combine this technology with a novel framework on beamlet adaptation. While some of our methods will improve photon therapy as well, we will focus on proton therapy because it offers unique opportunities to dose verification in vivo as well as unique challenges due to range uncertainties. Our methodology will be made available to the entire proton therapy community.

NCI R01 CA248901          Developing whole-body computational phantoms for blood dosimetry to model the impact of radiation on the immune system
This proposal will develop methods to quantify the interaction of radiation with the immune system, particularly the blood (i.e., circulating lymphocytes). We envision that future treatment planning in radiation oncology will treat lymphatic nodes and the blood as organs at risk and include them in the treatment optimization process so as to influence the level at which the radiation treatment impacts the immune system of the patient. During radiation therapy, depletion of circulating lymphocytes originates mainly from (1) immediate cell killing during irradiation of blood vessels, and thus circulating lymphocytes, within the treatment field and (2) to a lesser extent, the radiation dose to lymphocytes residing within lymphoid organs that can mobilize their lymphocyte population upon systemic depletion. There are currently no whole-body computational phantoms available that can facilitate the calculation of blood or lymphocyte dose-volume histograms. However, this tool is a prerequisite to the use of bio-mathematical models for clinical trial design. The phantoms to be developed in this study will be the first to fill this urgent need for the radiation therapy and research communities. In addition to the overall innovative nature of this project, several of our methods are novel and have never been employed in our field: • The first use of tetrahedral mesh structures to model blood vessels (SA1) • The first implementation of a whole-body compartment model for blood flow (SA2) • The first four-dimensional modeling of blood flow using vasculature structures (SA3) • The first model of the mouse vasculature for pre-clinical studies (SA4)

NIBIB R01 EB031102        Constrained Disentanglement (CODE) Network for CT Metal Artifact Reduction in Radiation Therapy

A majority of cancer patients receive radiation therapy as a critical part of their treatment, and many of these patients have metal objects leading to metal-induced CT artifacts. Metal artifacts compromise or preclude radiation therapy in an estimated 15% of all radiation therapy patients. Our overall goal is to eliminate CT metal artifacts in general and improve RT in particular using an integrated deep learning solution.

NCI R01 CA187003          TOPAS – nBio, a Monte Carlo tool for radiation biology research
The goal of this proposal is to continue our successful development of TOPAS-nBio, a Monte Carlo simulation toolkit specifically designed to connect research disciplines. TOPAS-nBio simulates the initial energy deposition events (physics), then follows the diffusion and reaction of chemical species (chemistry) to infer biological observables at the cell and organelle scale (biology). The developed application already lays the foundation to investigate biological effects of radiation in cell organelles using a mechanistic systems biology modeling approach. However, with constant advances in our understanding of cellular repair processes, the ques- tions asked by the radiation biology community are increasing in complexity. These advances, including more detailed information of various cells lines/types, deficiencies in DNA repair pathways and potential contributions of non-nuclear cell components, need to be considered to correctly describe cell response to radiation damages. Accordingly, in this renewal application, we focus on improving the accuracy of the simulations by including more representative chem- ical reactions and transitioning towards a predictive model that can be applied to specific cell types. To further extend the reach of TOPAS-nBio, we will include changes in the microenvi- ronment across tumor volumes and move towards mechanistic modeling of radiation effects in vivo. Thus, the new developments of TOPAS-nBio will offer predictions of biological outcome from the initial radiation track structure for various cell types for in vitro and in vivo experiments, and thereby drive hypothesis generation at the forefront of bio-physical research. TOPAS-nBio provides an ideal framework to include and test new effect models, cell lines or microenviron- mental conditions. Overall, TOPAS-nBio will continue the mission to advance our under- standing of the fundamental response of tissue to radiation.

NCI R21 CA252562           Understanding the importance of dose-rate variations for patient treatments in FLASH and conventional radiation therapy
Radiation therapy has been an important component in the treatment of cancer for many decades. While the parameters of tumor control have been relatively well understood, normal tissue complication probabilities (NTCPs) are often only thought of as constraining factors in the design of a treatment regimen. However, with continuously improving treatments of primary lesions, NTCP and their impact on the quality of life have moved into the focus of research. One of the most prominent methods reported to spare healthy tissue is FLASH radiation therapy, i.e. ultrafast (>40 Gy/s) irradiations, which reportedly results in incredible tissue sparing effects without compromising efficacy for tumor cure. Conversely, very low dose-rate irradiations have also been reported to offer protective features. Together, these experiments suggest that the current clinical routine, treating patients with a medium dose-rate of ~2 Gy/min, could in fact be the least favorable when considering healthy tissue side effects. In clinical practice, patients are treated with a variety of radiation treatment modalities. While the resulting target doses are similar across modalities, the dose delivered to the normal tissue and the time structure of the delivery can vary significantly. Despite the range of dose-rates across treatment plans, the biological effect is estimated only based on the total dose received. We hypothesize that dose-rate plays an important role in the outcome of radiation therapy that can be exploited for specific treatment scenarios. For extreme cases such as FLASH therapy, averaged dose-rates do not capture the relevant time structures adequately. We will apply Monte Carlo simulations to determine time structures from the clinical scale of minutes (spot scanning / gantry rotation time) to nanoseconds (intra-spot delivery time) and assess potential effects on healthy tissue sparing that would improve the quality of life for radiation therapy patients.

NCI R21 CA248118          A Computational Method to Calculate the Radiation Dose to Circulating Lymphocytes
There is growing enthusiasm in response to emerging data that combining immunotherapy with radiation therapy (RT) can increase response rates. However, persistent immunosuppression caused by radiation itself appears to limit this synergy. The effects of the exact RT delivery parameters (radiation modality, fractionation scheme, daily radiation exposure time and radiation dose rate) on the patient’s lymphocytes remain unknown, and there are currently no methods to calculate the radiation dose to circulating lymphocytes. The objective of this proposal is to develop a computational model to simulate the radiation dose to the lymphocyte population during intracranial irradiation based on vascular segmentation (SA1). The blood flow in the rest of the body will be modeled by a simplified Markov chain formalism. This will be combined with the patient-specific, time-dependent dose delivery information to simulate the dose to the circulating lymphocytes using a generalized Monte-Carlo approach. Furthermore we will validate our computational framework in patients treated with (conventional) photon and proton therapy. Due to the different dose distributions and time courses between proton and photon patients, we will be able to correlate the measured depletion in vivo to the patient-specific lymphocyte dose calculation to validate our computational model (SA2). Quantifying the dose delivered to the lymphocytes has great clinical potential and actionable significance because of the ease to modify radiation delivery parameters. Accurate knowledge of this effect would be transformative for the implementation of immunotherapy trials that are augmented with RT (>100 trials currently recruiting patients). Accurate dosimetry for circulating lymphocytes can control for variability among patients and will be key for the correct interpretation of trial results.
NCI U24 CA215123          The TOPAS Tool for Particle Simulation, a Monte Carlo Simulation Tool for Physics, Biology and Clinical Research
The TOPAS TOol for PArticle Simulation, launched on NCI funding in 2009, is a breakthrough software project that struck down a usability barrier that was limiting cancer research and treatment. Improvements to radiotherapy and imaging require understanding how subatomic particles travel through apparatus and tissue. The most precise calculations of such motion follow the Monte Carlo (MC) method. Yet MC’s painstaking specialized computer programming techniques had limited its availability to a small number of specialists. TOPAS brings a reliable, experimentally validated and easy-to-use MC tool within reach of every physicist. Requiring no programming knowledge, TOPAS provides nearly unlimited flexibility. It enables both clinical applications (e.g. high precision patient dose calculation) and cutting edge research (e.g. four dimensional time-of-flight simulations for detector developments), while its design promotes inter-institutional collaboration. In 2013, on a second NCI award, TOPAS was expanded from its initial focus on proton therapy physics to also cover radiation biology. TOPAS has been widely accepted in proton therapy physics and biology with 272 users at 121 institutions in 24 countries, but those working on other radiotherapy modalities and medical imaging lack such a tool. We seek to address these needs, creating the only fully integrated platform for advanced radiotherapy including multi-modality treatments and a broad range of image guidance. We shall: Specific Aim 1: Enhance the TOPAS Environment for User-Friendly Interactive Modeling and Simulation · Expand support for multi-processor, cluster, cloud and grid environments · Improve I/O compatibility with other medical physics standards · Improve computational speed and Graphical User Interface Specific Aim 2: Extend TOPAS Capabilities for Translational and Clinical Applications · Library of radiotherapy and imaging components, simplify simulation of complex therapy, QA and shielding · Biological models for radiation protection and pre-clinical research · Imaging systems and patient simulation, including more complex patient models Specific Aim 3: Maintain TOPAS for all User Communities · Respond to changes in underlying software packages and operating systems · Expand automated regression testing system for quality control Specific Aim 4: Disseminate TOPAS with Full Participation in ITCR Program Activities · Disseminate TOPAS through workshops at key conferences and web site · Provide user support through online user forum, web-based training and twice-yearly in-person trainings · Develop TOPAS user collaboration, initiate projects to address key user needs identified post-award, maintain depository for users to exchange customizations and extensions, move TOPAS to open source           
NCI K99 CA267560                     Radiation dosimetry for alpha-particle radiopharmaceutical therapy and application to pediatric neuroblastoma
Radiopharmaceutical treatments with α-particles represent a promising approach to treat some tumors and metastases. This modality leverages the short range of α-particles, up to tens of microns, to deliver radiation only to cancer cells while sparing the surrounding healthy tissue. To do so, an α-emitting radionuclide is bounded to an affinitive ligand which is used to target biomolecules expressed in tumoral cells. Currently, here are several clinical applications either approved, such as 223Ra for the treatment of bony metastases, or under investigation. Particularly, α-RPT could be used for the treatment of high-risk pediatric neuroblastoma, whose prognosis keeps poor. As the rationale behind radiopharmaceutical treatments is to exploit the differential amount of radiation imparted to tumors and healthy tissue, a rigorous determination of radiation dosimetry and effects is requested to develop this technique to their full extent. Starting with the study of α-particles in general, this research will be oriented to the treatment of pediatric neuroblastoma using the radiopharmaceutical [211At]MM4, which targets the overexpression of PARP-1 proteins in these tumors.  First, microdosimetric calculations will be connected with actual damage to the DNA using the Monte Carlo toolkit TOPAS and its extension for subcellular structures, TOPAS-nBio. Second, initial damage to neuroblastoma cell lines will be studied using the affinity of [211At]MM4 for PARP-1 in these cell lines to create realistic sub-cellular models of α-particle irradiation. Permanent damage after the occurrence of repair mechanisms will be also modelled assessed through experimental data published by Dr. Makvandi’s group from the University of Pennsylvania. Finally, biodistribution of radiopharmaceutical across organs and blood in animal models and phantoms will be assessed and used to predict treatment outcomes. The principal investigator will use the experience and expertise of his mentoring team (Dr. Harald Paganetti and Dr. Jan Schuemann) to learn the skills and abilities necessary to accomplish the proposed research. He will also attend seminars, coursework and conferences on radiobiology, Monte Carlo simulations and grant writing and leadership skills, which will ensure a strong foundation for running an independent laboratory after this project.

NCI contract 2020A003480          Monte Carlo for Pediatric Proton Epidemiology

Epidemiological studies on the long-term effect of radiation therapy (such as the development of a second radiation-induced cancer) require reconstruction of the primary and secondary (scattered) dose delivered to the patient at the time of treatment.

The long-term goal of this project is to 

a) develop a generic framework to accomplish this
b) to apply the framework to pediatric proton therapy patients at the MGH 

Damon Runyon-Rachleff Foundation

Using extreme dose rates to protect healthy tissue in proton radiation therapy
The overarching theme of this proposal is to determine if extreme dose-rate (EDR, also termed Flash) proton therapy spares normal tissues more than conventional dose-rate (CDR) proton therapy. Flash sparing effects have been reported for healthy tissue first and predominantly for electron irradiations. At the same time, tumors seem not to show a differential response, promising an increase in the therapeutic ratio. While existing electron irradiators can only be used for superficial lesions (e.g. skin), current proton delivery systems are already capable of producing EDR treatment fields for deep seated tumors, promising direct clinical impact. 

Brain Tumor Charity

Extreme dose rate proton therapy – reducing side effects for brain cancer treatments
The goal of this project is to reduce the impact of radiation therapy on the brain for small brain tumors.

Swiss National Science Foundation

Online Adaptive Proton Therapy Using Different Imaging Techniques
The goal of this project is to explore the adaptive treatment workflow in proton therapy considering various different in-room imaging modalities.