Research in biophysics from 1958. MD 1964. PhD Biophysics 1969. GP specialist 1971, diagnostic radiology 1973. Associate professor biophysics 1969-73 and diagnostic radiology 1973-83. Professor of radiology at the Karolinska institute 1984-2006. Professor emeritus from 2006. Assistant head of paediatric radiology at Karolinska 1973-77, head of radiology, Sachs paediatric hospital Stockholm 1977-83. Chairman Diagnostic radiology, Huddinge university hospital 1984-87 and Karolinska hospital 1987 to 2006. Professor and Chairman of the Board for the Center for Medical Imaging science and Visualization, Linkoping University since 2006. Consulting Professor at the Department of Radiology, Stanford University since 2013.

Fellow pediatric cardiac imaging UCSF 1975, visiting professor and responsible for pediatric MRI UCSF 1983-84 and visiting professor at Stanford University (2004-2012) and co-director of the strategic Center for Biomedical Imaging at Stanford (2007-present). Adjunct Professor of Radiology at UCSF 1984-2009 and Michigan State since 1991. Author of 230 scientific articles and 6 books. Permanent member Nobel Assembly for Physiology and Medicine 1986-2006. President elect and President of the Nobel Assembly 2002-2003. Trustee of the Nobel Foundation 2002-2006. Member of the International Commission on Radiological Protection, committee 3, Medicine since 1992. Honorary member of 16 radiological societies including the Society for Pediatric Radiology, and the European Society for Paediatric Radiology. Gold medal of the European Society of Radiology, Asian Oceanian Society of Radiology.

President of: International Congress of Paediatric Radiology 1991, Swedish Society of Medical Radiology 1995-97, European Congress of Radiology 1995-97, European Association of Radiology 1997-99, Swedish Union of Radiologists 1999-2005, and Funding President International Society for Strategic Studies in Radiology 1999-2003. Treasurer International Society of Radiology 2000-2005, President Elect 2006-2008, President 2008-2010. Past President 2010-2012.

Academic Appointments

Honors & Awards

  • Honorary Member, Japanese Radiological Society (2001)
  • Chairman elect, Nobel Assembly at the Karolinska Institute (2002)
  • Member, Nobel Committee for Medicine and Physiology (2002-2003)
  • Trustee, Nobel Foundation (2002)
  • Honorary Member, Alpha Omega Alpha Honor Medical Society (2003)
  • Chairman, Nobel Assembly at the Karolinska Institute (2003)
  • Honorary Fellow, American College of Radiology (2004)
  • Honorary member, The Belarusian Society of Radiology (2004)
  • President Elect, International Society of Radiology (2006)
  • Chairman of the board, Center for Medical Imaging Science and Visualization (2006)
  • Honorary President, CARS Computer Aided Radiology and Surgery (2006)
  • Honorary Member, Norwegian Society of Radiology (2007)
  • Co-Chairman, Nobel Symposium on Molecular Imaging (2007)
  • President, International Society of Radiology (2008)
  • Tom Nisbet Orator, Royal Australian and New Zealand College of Radiology (2008)
  • Special Presidential Award, RSNA, Radiological Society of North America (2010)
  • Honorary Member, Chinese Radiological Society (2011)
  • Beclere Medal, International Society of Radiology (2012)
  • Gold Medal, Asian Oceanian Society of Radiology (2012)
  • First recipient of Dr. Andrew and Margaret Bruce Visiting Scholarship in Surgical Innovation, Queen's University, Kingston, Ontario, Canada (2012)

Research & Scholarship

Current Research and Scholarly Interests

As a general pediatric radiologist with a biophysical background I am interested in mentoring projects in all of pediatric radiology except radiology of the central nervous system. My specific research areas in the past have been pediatric cardiac, urogenital, and oncologic imaging. A specific area of interest has been measurements in pediatric radiology especially for evaluation of normal versus abnormal size of structures, organs etc.


Graduate and Fellowship Programs


All Publications

  • Radiologic protection in pediatric radiology: ICRP recommendations PEDIATRIC RADIOLOGY Sanchez, R., Khong, P., Ringertz, H. 2013; 43 (8): 920-921

    View details for DOI 10.1007/s00247-013-2703-4

    View details for Web of Science ID 000322119000004

    View details for PubMedID 23636541

  • ICRP publication 121: radiological protection in paediatric diagnostic and interventional radiology. Annals of the ICRP Khong, P., Ringertz, H., Donoghue, V., Frush, D., Rehani, M., APPELGATE, K., Sanchez, R. 2013; 42 (2): 1-63


    Paediatric patients have a higher average risk of developing cancer compared with adults receiving the same dose. The longer life expectancy in children allows more time for any harmful effects of radiation to manifest, and developing organs and tissues are more sensitive to the effects of radiation. This publication aims to provide guiding principles of radiological protection for referring clinicians and clinical staff performing diagnostic imaging and interventional procedures for paediatric patients. It begins with a brief description of the basic concepts of radiological protection, followed by the general aspects of radiological protection, including principles of justification and optimisation. Guidelines and suggestions for radiological protection in specific modalities - radiography and fluoroscopy, interventional radiology, and computed tomography - are subsequently covered in depth. The report concludes with a summary and recommendations. The importance of rigorous justification of radiological procedures is emphasised for every procedure involving ionising radiation, and the use of imaging modalities that are non-ionising should always be considered. The basic aim of optimisation of radiological protection is to adjust imaging parameters and institute protective measures such that the required image is obtained with the lowest possible dose of radiation, and that net benefit is maximised to maintain sufficient quality for diagnostic interpretation. Special consideration should be given to the availability of dose reduction measures when purchasing new imaging equipment for paediatric use. One of the unique aspects of paediatric imaging is with regards to the wide range in patient size (and weight), therefore requiring special attention to optimisation and modification of equipment, technique, and imaging parameters. Examples of good radiographic and fluoroscopic technique include attention to patient positioning, field size and adequate collimation, use of protective shielding, optimisation of exposure factors, use of pulsed fluoroscopy, limiting fluoroscopy time, etc. Major paediatric interventional procedures should be performed by experienced paediatric interventional operators, and a second, specific level of training in radiological protection is desirable (in some countries, this is mandatory). For computed tomography, dose reduction should be optimised by the adjustment of scan parameters (such as mA, kVp, and pitch) according to patient weight or age, region scanned, and study indication (e.g. images with greater noise should be accepted if they are of sufficient diagnostic quality). Other strategies include restricting multiphase examination protocols, avoiding overlapping of scan regions, and only scanning the area in question. Up-to-date dose reduction technology such as tube current modulation, organ-based dose modulation, auto kV technology, and iterative reconstruction should be utilised when appropriate. It is anticipated that this publication will assist institutions in encouraging the standardisation of procedures, and that it may help increase awareness and ultimately improve practices for the benefit of patients.

    View details for DOI 10.1016/j.icrp.2012.10.001

    View details for PubMedID 23218172

  • A statement about authorship from individual members of the International Society for Strategic Studies in Radiology (IS3R) EUROPEAN RADIOLOGY Bryan, R. N., Cerri, G., Choi, B. I., Claussen, C. D., Dai, J., Debatin, J. F., Dixon, A. K., Donoso, L., Dunnick, N. R., Enzmann, D., Feng, X., Frija, G., Gambhir, S. S., Monaco, R. G., Gharbi, H. A., Golding, S., Graif, M., Grenier, P., Grossman, R. I., Guenther, R. W., Herold, C. J., Hillman, B., Hricak, H., Husband, J. E., Jackson, V., Jost, G., Kalender, W. A., Khong, P., Kim, D., Kressel, H. Y., Krestin, G. P., Kuribayashi, S., Le Bihan, D., Lewin, J. S., Margulis, A., Maynard, C. D., McNeil, B., Mezrich, R., Nakamura, H., Ohtomo, K., Palko, A., Pelc, N. J., Prokop, M., Ratib, O., Reiser, M., Ringertz, H., Rubin, G., Schoenberg, S., Schwaiger, M., Seltzer, S. E., Sinitsyn, V. E., Sostman, H. D., Sugimura, K., Tan, L., Ternovoy, S., Thrall, J. H., von Schulthess, G. K., Weissleder, R., Wolf, K., Zerhouni, E. 2013; 23 (1): 1-2

    View details for DOI 10.1007/s00330-012-2713-x

    View details for Web of Science ID 000312324500001

    View details for PubMedID 23184074

  • Radiological protection in paediatric computed tomography. Annals of the ICRP Khong, P., Frush, D., Ringertz, H. 2012; 41 (3-4): 170-178


    It is well known that paediatric patients are generally at greater risk for the development of cancer per unit of radiation dose compared with adults, due both to the longer life expectancy for any harmful effects of radiation to manifest, and the fact that developing organs and tissues are more sensitive to the effects of radiation. Multiple computed tomography (CT) examinations may cumulatively involve absorbed doses to organs and tissues that can sometimes approach or exceed the levels known from epidemiological studies to significantly increase the probability of cancer development. Radiation protection strategies include rigorous justification of CT examinations and the use of imaging techniques that are non-ionising, followed by optimisation of radiation dose exposure (according to the 'as low as reasonably achievable' principle). Special consideration should be given to the availability of dose reduction technology when acquiring CT scanners. Dose reduction should be optimised by adjustment of scan parameters (such as mAs, kVp, and pitch) according to patient weight or age, region scanned, and study indication (e.g. images with greater noise should be accepted if they are of sufficient diagnostic quality). Other strategies include restricting multiphase examination protocols, avoiding overlapping of scan regions, and only scanning the area in question. Newer technologies such as tube current modulation, organ-based dose modulation, and iterative reconstruction should be used when appropriate. Attention should also be paid to optimising study quality (e.g. by image post-processing to facilitate radiological diagnoses and interpretation). Finally, improving awareness through education and advocacy, and further research in paediatric radiological protection are important to help reduce patient dose.

    View details for DOI 10.1016/j.icrp.2012.06.017

    View details for PubMedID 23089016

  • Global Quality Imaging: Emerging Issues JOURNAL OF THE AMERICAN COLLEGE OF RADIOLOGY Lau, L. S., Perez, M. R., Applegate, K. E., Rehani, M. M., Ringertz, H. G., George, R. 2011; 8 (7): 508-512


    Quality imaging may be described as "a timely access to and delivery of integrated and appropriate procedures, in a safe and responsive practice, and a prompt delivery of an accurately interpreted report by capable personnel in an efficient, effective, and sustainable manner." For this article, radiation safety is considered as one of the key quality elements. The stakeholders are the drivers of quality imaging. These include those that directly provide or use imaging procedures and others indirectly supporting the system. Imaging is indispensable in health care, and its use has greatly expanded worldwide. Globalization, consumer sophistication, communication and technological advances, corporatization, rationalization, service outsourcing, teleradiology, workflow modularization, and commoditization are reshaping practice. This article defines the emerging issues; an earlier article in the May 2011 issue described possible improvement actions. The issues that could threaten the quality use of imaging for all countries include workforce shortage; increased utilization, population radiation exposure, and cost; practice changes; and efficiency drive and budget constraints. In response to these issues, a range of quality improvement measures, strategies, and actions are used to maximize the benefits and minimize the risks. The 3 measures are procedure justification, optimization of image quality and radiation protection, and error prevention. The development and successful implementation of such improvement actions require leadership, collaboration, and the active participation of all stakeholders to achieve the best outcomes that we all advocate.

    View details for DOI 10.1016/j.jacr.2010.12.028

    View details for Web of Science ID 000306201500013

    View details for PubMedID 21723489

  • Global Quality Imaging: Improvement Actions JOURNAL OF THE AMERICAN COLLEGE OF RADIOLOGY Lau, L. S., Perez, M. R., Applegate, K. E., Rehani, M. M., Ringertz, H. G., George, R. 2011; 8 (5): 330-334


    Workforce shortage, workload increase, workplace changes, and budget challenges are emerging issues around the world, which could place quality imaging at risk. It is important for imaging stakeholders to collaborate, ensure patient safety, improve the quality of care, and address these issues. There is no single panacea. A range of improvement measures, strategies, and actions are required. Examples of improvement actions supporting the 3 quality measures are described under 5 strategies: conducting research, promoting awareness, providing education and training, strengthening infrastructure, and implementing policies. The challenge is to develop long-term, cost-effective, system-based improvement actions that will bring better outcomes and underpin a sustainable future for quality imaging. In an imaging practice, these actions will result in selecting the right procedure (justification), using the right dose (optimization), and preventing errors along the patient journey. To realize this vision and implement these improvement actions, a range of expertise and adequate resources are required. Stakeholders should collaborate and work together. In today's globalized environment, collaboration is strength and provides synergy to achieve better outcomes and greater success.

    View details for DOI 10.1016/j.jacr.2011.01.005

    View details for Web of Science ID 000306201300010

    View details for PubMedID 21531309

  • Globalization of P4 Medicine: Predictive, Personalized, Preemptive, and Participatory-Summary of the Proceedings of the Eighth International Symposium of the International Society for Strategic Studies in Radiology, August 27-29, 2009 RADIOLOGY Bradley, W. G., Golding, S. G., Herold, C. J., Hricak, H., Krestin, G. P., Lewin, J. S., Miller, J. C., Ringertz, H. G., Thrall, J. H. 2011; 258 (2): 571-582


    In August 2009, the International Society for Strategic Studies in Radiology held its eighth biennial meeting. The program focused on the globalization of predictive medicine--or P4 medicine--as it relates to the practice of radiology and radiology research. P4 medicine refers to predictive, personalized, preemptive, and participatory medicine and was the inspiration of Elias Zerhouni, MD, former director of the National Institutes of Health. This article is a summary of some of the key concepts presented at the meeting by an international group of radiologists, imaging scientists, and leaders of industry. In predictive medicine, imaging and imaging-related technologies will likely play an increasing role in the early detection of disease and, thus, the preemption of the development of advanced, hard-to-treat disease. Research into systems biology and molecular imaging promises to personalize medicine, facilitating the provision of the right care to the right patient at the right time. In participatory medicine, increasing interactions with referring physicians and patients will be helpful in raising awareness and recognition of the role of radiologists and will have a positive effect on professionalism. There is also a need to increase awareness of the vital role of radiologists as imaging and radiation safety experts who evaluate the necessity and appropriateness of examinations, monitor performance quality, and are available for postexamination consultations.

    View details for DOI 10.1148/radiol.10100568

    View details for Web of Science ID 000286653700028

    View details for PubMedID 21273521

  • Standardizing resistive indices in healthy pediatric transplant recipients of adult-sized kidneys PEDIATRIC TRANSPLANTATION Gholami, S., Sarwal, M. M., Naesens, M., Ringertz, H. G., Barth, R. A., Balise, R. R., Salvatierra, O. 2010; 14 (1): 126-131


    Small pediatric recipients of an adult-sized kidney have insufficient renal blood flow early after transplantation, with secondary chronic hypoperfusion and irreversible histological damage of the tubulo-interstitial compartment. It is unknown whether this is reflected by renal resistive indices. We measured renal graft resistive indices and volumes of 47 healthy pediatric kidney transplant recipients of an adult-sized kidney in a prospective study for six months post-transplant. A total of 205 measurements were performed. The smallest recipients (BSA or= 1.5 m(2) (p < 0.0001). Resistive indices increased during the first six months in the smallest recipients (p = 0.02), but not in the two larger recipient groups (BSA 0.75-1.5 m(2) and >or=1.5 m(2)). All three BSA groups showed a reduction in renal volume after transplantation, with the greatest reduction occurring in the smallest recipients. In conclusion, renal transplant resistive indices reflect pediatric recipient BSA dependency. The higher resistance to intra-renal vascular flow and significant decrease in renal volume in the smallest group likely reflect accommodation of the size discrepant transplanted adult-sized kidney to the smaller pediatric recipient vasculature with associated lower renal artery flow.

    View details for DOI 10.1111/j.1399-3046.2009.01180.x

    View details for Web of Science ID 000273478100024

    View details for PubMedID 19413712

  • Three-Dimensional MRI Volumetric Measurements of the Normal Fetal Colon AMERICAN JOURNAL OF ROENTGENOLOGY Rubesova, E., Vance, C. J., Ringertz, H. G., Barth, R. A. 2009; 192 (3): 761-765


    The use of fetal MRI markedly improves characterization of abdominal congenital anomalies. Accurate prenatal diagnosis of the level and cause of congenital intestinal obstruction is desired for optimal parental counseling and perinatal care. Because accurate diagnosis would be aided by nomograms of colonic volume, this study was conducted to determine normal colonic volumes at different gestational ages.This retrospective study consisted of a review of 83 fetal MRI examinations performed on fetuses with no gastrointestinal abnormalities. MRI was performed with a 1.5-T system. Axial, sagittal, and coronal T1-weighted fast gradient-refocused echo images were acquired at TR/TE, 165/2.6; flip angle, 90 degrees; matrix size, 384 x 192; slice thickness, 5 mm; field of view, 38 cm(2). Two investigators determined the region of interest in the colon by outlining areas of high signal intensity of meconium slice by slice. They then calculated colonic luminal volume in the regions of interest. Colonic luminal volumes were reported relative to gestational age and abdominal circumference. Normative curves were generated, and interobserver and intraobserver analyses were performed.Seventeen of the 83 fetuses (20%) were excluded because of movement artifacts on the images. Normal colonic luminal volume increased exponentially with gestational age and abdominal circumference. The range of colonic luminal volumes at 20-37 weeks' gestational age was 1.1-65 mL. Variation of volume was greater at advanced gestational age. Interobserver and intraobserver correlation was good.This study yielded preliminary volumetric measurements of the normal fetal colon at 20-37 weeks of gestational age that suggest the fetal colon grows exponentially.

    View details for DOI 10.2214/AJR.08.1504

    View details for Web of Science ID 000264005700032

    View details for PubMedID 19234275

  • Reinventing radiology in a digital and molecular age: Summary of proceedings of the sixth biannual symposium of the international society for strategic studies in radiology ((ISR)-R-3), august 25-27, 2005 RADIOLOGY Krestin, G. P., Miller, J. C., Golding, S. J., Frija, G. G., Glazer, G. M., Ringertz, H. G., Thrall, J. H. 2007; 244 (3): 633-638

    View details for DOI 10.1148/radiol.2443070165

    View details for Web of Science ID 000248993500003

    View details for PubMedID 17690325

  • Cranial CT for diagnosis of intracranial complications in adult and pediatric patients during ECMO: Clinical benefits in diagnosis and treatment ACADEMIC RADIOLOGY Lidegran, M. K., Mosskin, M., Ringertz, H. G., Frenckner, B. P., Linden, V. B. 2007; 14 (1): 62-71


    To evaluate the clinical utility of cranial computed tomography (CT) in pediatric and adult patients during ongoing extracorporeal membrane oxygenation (ECMO) treatment from acute respiratory failure and to assess the frequency of intracranial hemorrhage (ICH) and infarction during the treatment.The medical records of 123 consecutive patients, 54 children (ages 3 months-17 years) and 69 adults (ages 18-62 years), treated with ECMO over a 10-year period were searched for cranial CT performed during ECMO. Indications for CT, CT findings, impact on clinical management, and patient outcome were noted. In addition, all CT scans were reviewed for the frequency of ICH or infarction.Seventy-eight patients had cranial CT while on ECMO. ICH or cerebral infarction were detected in 45 (37%) of the 123 patients. Eighteen patients (15%) had focal hemorrhage, 11 (9%) focal infarction, and 16 (13%) general brain edema. In 16 of the 45 patients, the CT findings were decisive to withdraw the ECMO treatment. Five patients were weaned from ECMO, and in four patients the findings motivated cranial surgery during ECMO. In the remaining 20 patients with less extended intracranial pathology, the ECMO treatment was continued with high survival.Cranial CT has an important role during ECMO treatment to reveal or exclude severe intracranial complications where ECMO treatment should be discontinued. Less severe complications have a favorable prognosis with continued treatment. Our study suggests an underreporting of intracranial complications in adults and pediatric patients on ECMO because of low utilization of neuroimaging.

    View details for DOI 10.1016/j.acra.2006.10.004

    View details for Web of Science ID 000243363800008

    View details for PubMedID 17178367

  • Prenatal diagnosis of horseshoe lung and esophageal atresia PEDIATRIC RADIOLOGY Goldberg, S., Ringertz, H., Barth, R. A. 2006; 36 (9): 983-986


    We present a case of horseshoe lung (HL) and esophageal atresia suspected prenatally on US imaging and confirmed with fetal MRI. Prenatal diagnosis of HL and esophageal atresia allowed for prenatal counseling and informed parental decisions.

    View details for DOI 10.1007/s00247-006-0242-y

    View details for Web of Science ID 000239591400015

    View details for PubMedID 16767398

  • Chest and abdominal CT during extracorporeal membrane oxygenation: Clinical benefits in diagnosis and treatment ACADEMIC RADIOLOGY Lidegran, M. K., Ringertz, H. G., Frenckner, B. P., Linden, V. B. 2005; 12 (3): 276-285


    This study aims to evaluate the clinical usefulness of thoracic and abdominal computed tomography (CT) as an adjunct to bedside diagnostic imaging in patients on extracorporeal membrane oxygenation (ECMO) therapy because of severe acute respiratory failure.Imaging records for 118 consecutive thoracic and abdominal CT examinations performed in 63 patients (22 neonates, 15 children, and 26 adults) on ECMO therapy during an 8-year period were retrospectively reviewed. Reported CT findings were compared with concurrent bedside radiographs and ultrasounds. The clinical importance and effect on treatment of each CT finding was determined by reviewing the medical records.CT showed 30 clinically important complications in 20 different patients that directly impacted on the treatment, but were not diagnosed with bedside imaging. Of the 30 complications, 15 (50%) were surgically treated, 11 (37%) required percutaneous invasive procedures, and 4 (13%) were managed conservatively. Despite the serious complications, 13 of 20 patients (65%) survived.Both chest and abdominal CT have an important clinical role in patients on ECMO therapy because of acute respiratory failure, as a complement to bedside imaging, to exclude or show complications and expedite early invasive treatment, when needed.

    View details for DOI 10.1016/j.acra.2004.11.027

    View details for Web of Science ID 000227703800003

    View details for PubMedID 15766686

  • MRI: worth a Nobel Prize? Journal of the American College of Radiology Ringertz, H. G. 2005; 2 (1): 82-85

    View details for PubMedID 17411768



    We investigated the effect of the device known as the linear accelerator flow control (linear-rise) available on some angiographic power injectors used for delivering contrast medium. Its influence on catheter tip recoil during selective arteriography was evaluated in two glass models, which simulated assessment of catheter position in visceral and cerebral arterial branches. Contrast medium was injected over a clinical range with and without the linear flow accelerator in operation. Biplane high speed video recordings simultaneously referenced time in thousandths of seconds and the catheter position. The linear flow accelerator failed to prevent, but did delay, catheter tip recoil in proportion to the prolongation of contrast medium injection time. These laboratory results conformed with the findings of catheter behavior during similar experiments in animals undergoing arteriography.

    View details for Web of Science ID A1985ADW5000016

    View details for PubMedID 3988471



    Demarcating fixed points in cardiac ventricles in the dog by catheter placement of tantalum coils has been shown to provide an excellent physiologic model. A new method emplying direct ventricular puncture has been developed for implanting these markers. The method has several advantages over an earlier peripheral catheter technique. Apical approach allows easier screw placement near the aortic and pulmonary valves. Peripheral vessels are left intact and pressure monitoring as well as contrast medium injection can be performed through the same catheter.

    View details for Web of Science ID A1979JD38000004

    View details for PubMedID 525413