Mohan Doss, PhD, MCCPM
- BSc, Physics, Madras University, Madras, India, 1971
- MSc, Physics, Indian Institute of Technology, Kanpur, India, 1973
- MS, Physics, Carnegie-Mellon University, 1975
- PhD, Physics, Carnegie-Mellon University, 1980
- Member, Canadian College of Physicists in Medicine (Nuclear Medicine Physics), 1994
Honors & Awards
- Outstanding Leadership Award in the Field of Dose Response, International Dose-Response Society, 2014
- FCCC Ovarian SPORE Career Development Award, 2003
Health Effects of Low-Dose Radiation and PET Imaging in Oncology
- Exploring cancer prevention and treatment using low-dose radiation.
- Control of non-cancer diseases using low-dose radiation.
- Optimization of PET Imaging in Oncology.
- Biodistribution and Dosimetry of Novel PET Imaging Agents.
- PET Imaging of Y-90 Microspheres.
Cancer Prevention and Treatment Using Low-Dose Radiation: Whereas the carcinogenic nature of high dose radiation is well known, there is considerable disagreement in the scientific community about the cancer risk from low-dose radiation (LDR). The traditional assumption generally accepted since the 1950s is that cancer risk due to radiation can be extrapolated from high doses to low doses linearly with no threshold (known as the LNT model). Our current radiation safety regulations and practices are based on the LNT model. Though many publications have claimed LDR is carcinogenic, major flaws have been identified in such publications negating their conclusions. The most important data for estimating health effects of radiation are the atomic bomb survivor data. These data, until recently, have appeared to support the LNT model. However, following the update in 2012, these data no longer support the LNT model since there is a significant curvature in the dose-response relationship, which is consistent with the concept of radiation hormesis. There is also considerable amount of additional evidence supporting the idea that LDR reduces cancers. Hence, LDR treatment may present an alternative method of preventing and treating cancers. A major change in the current radiation safety paradigm would be needed to facilitate the use of LDR for cancer prevention and therapy.
Control of Non-Cancer Diseases Using Low-Dose Radiation: Another potential benefit of low dose radiation is control of aging-related non-cancer diseases through stimulation of production of antioxidants. Since many of these non-cancer diseases are caused by oxidative damage, it may be possible to stabilize the diseases if further oxidative damage can be prevented using LDR to stimulate antioxidants and other defenses. We have completed a study of the effect of LDR on Parkinson’s disease symptoms in a rat model of the disease. We have observed promising results and are in the process of publishing them.
Biodistribution and Dosimetry of Novel PET Imaging Agents: When new PET imaging agents are developed to probe different biological processes, it is necessary to evaluate their safety by measuring the biodistribution of the agent and estimating the radiation dose to different organs. It is also important to know whether the normal biodistribution may obscure the anticipated biodistribution from the disease process. We have developed tools and methodology to do this evaluation using our PET/CT scanner. In a typical study, subjects are injected with the new imaging agent, and five consecutive whole body PET/CT scans are acquired over a period of about 2 hours. By examining the PET images and quantifying the uptake in the organs at the different time points, the radiation dose to the organs are estimated using the OLINDA/EXM software, and any critical organs are identified. We have studied the following F-18 labeled compounds thus far: HX-4 and VM4-037 (hypoxia imaging agents), RGD-K5 (angiogenesis marker) and W-372 (amyloid β plaque imaging agent). Studies of additional compounds are being planned.
Quantitative PET imaging of Y-90: We are investigating methods of accurately quantifying the PET images from Y-90. The PET images can be utilized for estimating the radiation dose to the tumors and organs from Y-90 microspheres which are used to treat metastatic liver cancer. This can help in optimizing the treatment. We are participating in a multi-site study called QUEST, organized by one of the manufacturers of Y-90 microspheres.
Pre-clinical PET imaging of novel targeted drugs: We are also collaborating with other researchers in Developmental Therapeutics in performing pre-clinical PET imaging studies with new targeted imaging/therapy agents to verify their tumor targeting.
Pre-clinical Cerenkov imaging of Y-90 labeled novel drugs: In this collaborative project with Harvey Hensley of Microimaging facility, we are investigating the utility of Cerenkov imaging of distribution of Y-90 labeled imaging compounds in mice. This can be a very cost-effective way of determining tumor-targeting of Y-90 labeled imaging and/or therapy compounds.
Comments on "Studies of the mortality of atomic bomb survivors, Report 14, 1950-2003: an overview of cancer and noncancer diseases" (Radiat Res 2012; 177:229-43). M. Doss, B. L. Egleston and S. Litwin, Radiat Res 178, 244-245 (2012). PubMed
Biodistribution and Radiation Dosimetry of the Integrin Marker 18F-RGD-K5 Determined from Whole-Body PET/CT in Monkeys and Humans. Doss M, Kolb HC, Zhang JJ, Bélanger MJ, Stubbs JB, Stabin MG, Hostetler ED, Alpaugh RK, von Mehren M, Walsh JC, Haka M, Mocharla VP, Yu JQ. J Nucl Med. 53, 787-795 (2012). PubMed
Shifting the Paradigm in Radiation Safety. M. Doss, Dose Response. 10, 562-583 (2012). PubMed
Evidence Supporting Radiation Hormesis in Atomic Bomb Survivor Cancer Mortality Data. M. Doss, Dose Response. 10, 584-592 (2012). PubMed
Linear No-Threshold Model vs. Radiation Hormesis, M. Doss, Dose Response. 11, 480–497 (2013). PubMed
The importance of adaptive response in cancer prevention and therapy, M. Doss, Medical Physics, 40, 032302 (2013). PubMed
Low Dose Radiation Adaptive Protection to Control Neurodegenerative Diseases, M. Doss, Dose-Response, 12:277–287, 2014, PubMed
3D inpatient dose reconstruction from the PET-CT imaging of 90Y microspheres for metastatic cancer to the liver: Feasibility study, E. Fourkal, I. Veltchev, M. Lin, S. Koren, J. Meyer, M. Doss, J. Q. Yu, Medical Physics, 40, 081702 (2013); PubMed
Radiation doses from radiological imaging do not increase the risk of cancer, Mohan Doss, British Journal of Radiology, 87, 20140085, 2014. PubMed
Point/Counterpoint: low-dose radiation is beneficial, not harmful. Doss M, Little MP, Orton CG., Med Phys. 2014 Jul;41(7):070601, PubMed