Letter from the Editors

Article Outline

• Copyright

The editors are indebted to Dr. Shalom Kalnicki for serving as Guest Editor of this very important issue. The realization that molecular imaging with the use of positron emission tomography/computed tomography (PET/CT) can provide invaluable functional information to the radiation oncologist is just beginning to achieve some degree of maturity. Although recognition of the potential role of PET imaging in radiation oncology occurred several years ago, it is really the introduction of the PET/CT that has greatly stimulated this very important collaboration between nuclear medicine physicians and radiation oncologists. The potential for this combined approach to cancer treatment is impressive. There are concerns in the treatment of patients with cancer both in terms of not radiating areas of normal tissue and at the same time being sure to include all of the disease process. The use of PET to delineate areas of metabolic activity and CT to show anatomic changes provides the potential for the oncologist to fulfill both of these important needs. Proof of the efficacy of this combined imaging technique in radiation treatment planning will be difficult to acquire. Few centers would be willing to have a control group for a therapeutic approach that appears so valuable. This issue attempts to put into perspective the collaboration between the PET/CT and the treatment planning CT for practicing nuclear medicine and radiation oncology physicians. This approach is gaining increasing support and, at Montefiore Medical Center, we have had an intensive collaboration with Dr. Kalnicki and his colleagues. The use of PET/CT for treatment planning at our institution has grown by leaps and bounds and involves a close collaboration between the two departments. Other centers have similarly adopted this approach with impressive degrees of success.

The introductory article in this issue by Drs. Guha, Blaufox, Alfieri, and Kalnicki discusses in great detail the role of radiation treatment planning based on tumor biology rather than solely upon tumor morphology and sets the stage for understanding why this is such an important advance in cancer therapeutics. To first understand how PET could have a role in radiation oncology, it is necessary to review the article by Drs. Schöder and Ong that provides an excellent overview of the rationale and applications of molecular imaging for radiation oncology. The application of this useful technique is not a simple task and requires both a well informed nuclear medicine physician and a well informed radiation oncologist. It is important to pay close attention to the technical aspects of PET/CT fusion planning and to have this available in a carefully designed and coordinated setting. Dr. Brunetti and colleagues help us to understand how to set up a PET/CT treatment planning program and provide numerous important details. Drs. Mah and Chen move us a step further with an in depth discussion of the quandary in selecting the optimum treatment volume and the techniques that are currently available to help in this selection. Their quotation of Harold Johns, “if you can’t see it, you can’t hit it and if you can’t hit it, you can’t cure it” is cogent. It is exactly the problem suggested by this statement that PET helps to resolve.

Dr. Macapinlac takes us a step further in reviewing the clinical applications of PET/CT treatment planning. Finally, Drs. Ahn and Garg provide us with a detailed look at PET/CT in head and neck cancers. Dr. Macapinlac’s emphasis is on nonsmall cell lung cancer in his review, which is an area where we have had the greatest experience with PET imaging. However, the experience of Montefiore Medical Center has been that there is a very great need and interest on the part of head and neck surgeons for support in planning for treatment of their patients. Eleven percent of all of our diagnostic studies are directed at the head and neck. This is the fourth most frequently performed study and is still considerably less than the 21% of studies that are performed on the lung. Drs. Ahn and Garg make a strong case for the use of PET/CT for target delineation in this unfortunate disease. Their actions support their statements since a very significant number of the radiation oncology PET/CT correlations at Montefiore are done for head and neck patients.

An additional feature of this issue is a supplemental section also on radiation therapy but, in this case, nuclear medicine radiation therapy. It has been sponsored and supported by the International Atomic Energy Agency (IAEA). The project that is described in great detail was directed at the treatment of liver cancer. The publication of this supplemental section owes its origin to Dr. A. Padhy, who originally approached the editors about the possibility of a supplement. This concept has been strongly supported by Dr. M. Dondi, the head of the Nuclear Medicine Section of the Division of Human Health of the IAEA. The liver cancer project has been a very ambitious program of the International Atomic Energy Agency in the field of human health. It was performed under their program to link research and development with postgraduate education and training in developing countries. The resultant product of this research is ¹⁸⁸Re lipiodol. Its established safety and efficacy offers the possibility of clinical application in patients. It is particularly noteworthy that the program was developed with the collaboration of 7 researchers from several developing countries. Although it is a lesser but significant problem in the United States, liver cancer is a very great problem in many developing countries, and the potential of introducing a therapeutic modality that can be successful provides hope for many of these unfortunate patients. In addition to the contributors from developing countries, there has been considerable collaboration with other investigators including Drs. Divgi and Zanzonico who played an important role in the program. This supplemental section should be of interest to all readers in understanding liver cancer, understanding the potential role of nuclear medicine and its treatment, and providing some insight into the role of the IAEA in promoting education, medical research and technology transfer among nuclear medicine communities in developing countries.