Photo of Iain MacEwan, M.D.


Proton Therapy, Radiation Oncology



Proton Therapy, Radiation Oncology


California Protons Cancer Therapy Center

Medical Group / IPA


Medical School

University of California - San Diego


National Naval Medical Center


Loma Linda University Hospital Medical Center

Board Certifications

Radiation Oncology




Dr. MacEwan is a radiation oncologist who specializes in treating cancers in children. He has expertise in the most advanced photon and proton technologies and treats cancer using many modalities, including conformal radiation therapy (CRT), intensity-modulated radiation therapy (IMRT), image-guided radiation therapy (IGRT), stereotactic radiation surgery (SRS), and pencil beam proton therapy (PBT) / intensity-modulated proton therapy (IMPT).

As an assistant professor in the Department of Radiation Medicine and Applied Sciences at UC San Diego School of Medicine, Dr. MacEwan participates in the latest clinical trials while instructing medical students and residents.

His research has focused on the use of proton therapy in pediatric malignancies, including medulloblastoma and ependymoma. He also has completed research in health disparities and cancer outcomes. His research has appeared in journals such as Advances in Radiation Oncology, Oral Oncology, Magnetic Resonance Imaging, PloS One, and the Journal of Medicinal Chemistry.

Dr. MacEwan completed a residency in radiation oncology at Loma Linda University School of Medicine. He earned his medical degree at UC San Diego School of Medicine.

He is an active member of professional associations such as the American College of Radiology and the American Society for Radiation Oncology.

Outside of work, Dr. MacEwan enjoys spending time with his wife and young daughter. He is an avid surfer and also enjoys golf, tennis, and hiking in his hometown of Palm Springs, Calif.


Toward automatic beam angle selection for pencil-beam scanning proton liver treatments: A deep learning-based approach.
Kaderka R, Liu KC, Liu L, VanderStraeten R, Liu TL, Lee KM, Tu YE, MacEwan I, Simpson D, Urbanic J, Chang C

Post-treatment neuroendocrine outcomes among pediatric brain tumor patients: Is there a difference between proton and photon therapy?
Yip AT, Yu JD, Huynh-Le MP, Salans M, Unnikrishnan S, Qian AS, Xu R, Kaner R, MacEwan I, Crawford JR, Hattangadi-Gluth JA

Volumetric de-escalation and improved acute toxicity with proton craniospinal irradiation using a vertebral body-sparing technique.
Chou B, Hopper A, Elster J, Crawford JR, McConnell K, Chang A, Mundt AJ, MacEwan I

Variation in Proton Craniospinal Irradiation Practice Patterns in the United States: A Pediatric Proton Consortium Registry (PPCR) Study.
Connor M, Paulino AC, Ermoian RP, Hartsell WF, Indelicato DJ, Perkins S, Mangona V, DeNunzio N, Laack NN, Hill-Kayser C, Kwok Y, Chang JH, Yock T, MacEwan I

Wilms Tumor (Nephroblastoma), Version 2.2021, NCCN Clinical Practice Guidelines in Oncology.
Balis F, Green DM, Anderson C, Cook S, Dhillon J, Gow K, Hiniker S, Jasty-Rao R, Lin C, Lovvorn H, MacEwan I, Martinez-Agosto J, Mullen E, Murphy ES, Ranalli M, Rhee D, Rokitka D, Tracy EL, Vern-Gross T, Walsh MF, Walz A, Wickiser J, Zapala M, Berardi RA, Hughes M

Practice Patterns of Pediatric Total Body Irradiation Techniques: A Children's Oncology Group Survey.
Rassiah P, Esiashvili N, Olch AJ, Hua CH, Ulin K, Molineu A, Marcus K, Gopalakrishnan M, Pillai S, Kovalchuk N, Liu A, Niyazov G, Peñagarícano J, Cheung F, Olson AC, Wu CC, Malhotra HK, MacEwan IJ, Faught J, Breneman JC, Followill DS, FitzGerald TJ, Kalapurakal JA

Utility of Multi-institutional Pediatric Chart Rounds in the Age of Telemedicine
 Feng CH, Braunstein SE, MacEwan I

Utility of Multi-institutional Pediatric Chart Rounds in the Age of Telemedicine.
Feng CH, Braunstein SE, MacEwan I

Improving the Pediatric Patient Experience During Radiation Therapy-A Children's Oncology Group Study.
Holt DE, Hiniker SM, Kalapurakal JA, Breneman JC, Shiao JC, Boik N, Cooper BT, Dorn PL, Hall MD, Logie N, Lucas JT Jr, MacEwan IJ, Olson AC, Palmer JD, Patel S, Pater LE, Surgener S, Tsang DS, Vogel JH, Wojcik A, Wu CC, Milgrom SA

An open invitation to join the Pediatric Proton/Photon Consortium Registry to standardize data collection in pediatric radiation oncology.
Lawell MP, Indelicato DJ, Paulino AC, Hartsell W, Laack NN, Ermoian RP, Perentesis JP, Vatner R, Perkins S, Mangona VS, Hill-Kayser CE, Wolden SL, Kwok Y, Chang JH, Wilkinson JB, MacEwan I, Chang AL, Eaton BR, Ladra MM, Gallotto SL, Weyman EA, Bajaj BVM, Baliga S, Yeap BY, Berrington de Gonzalez A, Yock TI

Effects of vertebral-body-sparing proton craniospinal irradiation on the spine of young pediatric patients with medulloblastoma.
MacEwan I, Chou B, Moretz J, Loredo L, Bush D, Slater JD

Discovery of (1S,2R,3S,4S,5R,6R)-2-Amino-3-[(3,4-difluorophenyl)sulfanylmethyl]-4-hydroxy-bicyclo[3.1.0]hexane-2,6-dicarboxylic Acid Hydrochloride (LY3020371·HCl): A Potent, Metabotropic Glutamate 2/3 Receptor Antagonist with Antidepressant-Like Activity.
Chappell MD, Li R, Smith SC, Dressman BA, Tromiczak EG, Tripp AE, Blanco MJ, Vetman T, Quimby SJ, Matt J, Britton TC, Fivush AM, Schkeryantz JM, Mayhugh D, Erickson JA, Bures MG, Jaramillo C, Carpintero M, Diego JE, Barberis M, Garcia-Cerrada S, Soriano JF, Antonysamy S, Atwell S, MacEwan I, Condon B, Sougias C, Wang J, Zhang A, Conners K, Groshong C, Wasserman SR, Koss JW, Witkin JM, Li X, Overshiner C, Wafford KA, Seidel W, Wang XS, Heinz BA, Swanson S, Catlow JT, Bedwell DW, Monn JA, Mitch CH, Ornstein PL

Correction to The 2.5 Ã… Crystal Structure of the SIRT1 Catalytic Domain Bound to Nicotinamide Adenine Dinucleotide (NAD(+)) and an Indole (EX527 Analogue) Reveals a Novel Mechanism of Histone Deacetylase Inhibition.
Zhao X, Allison D, Condon B, Zhang F, Gheyi T, Zhang A, Ashok S, Russell M, MacEwan I, Qian Y, Jamison JA, Luz JG

Proton density water fraction as a biomarker of bone marrow cellularity: validation in ex vivo spine specimens.
MacEwan IJ, Glembotski NE, D'Lima D, Bae W, Masuda K, Rashidi HH, Mell LK, Bydder M

Structural context of disease-associated mutations and putative mechanism of autoinhibition revealed by X-ray crystallographic analysis of the EZH2-SET domain.
Antonysamy S, Condon B, Druzina Z, Bonanno JB, Gheyi T, Zhang F, MacEwan I, Zhang A, Ashok S, Rodgers L, Russell M, Gately Luz J

Race and competing mortality in advanced head and neck cancer.
Zakeri K, MacEwan I, Vazirnia A, Cohen EE, Spiotto MT, Haraf DJ, Vokes EE, Weichselbaum RR, Mell LK

The 2.5 Ã… crystal structure of the SIRT1 catalytic domain bound to nicotinamide adenine dinucleotide (NAD+) and an indole (EX527 analogue) reveals a novel mechanism of histone deacetylase inhibition.
Zhao X, Allison D, Condon B, Zhang F, Gheyi T, Zhang A, Ashok S, Russell M, MacEwan I, Qian Y, Jamison JA, Luz JG

See the full listing of this physician's publications on PubMed, a service of the National Library of Medicine. PubMed is a third-party website and not affiliated with Rady Children's Hospital-San Diego.

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