Information systems do not function independently. All systems should be interconnected and work in close cooperation. When linking to other systems, many department systems (e.g., the TPS, treatment delivery system, and treatment management system) require proprietary protocols and connection methods. These proprietary structures restrict selection and lead to high cost and huge effort during system upgrades and/or replacement.

Figure 13.1 illustrates the interoperability of the OIS. Patient demographic data should be exchanged between the HIS and the TMS by using the Health Level 7 (HL7) standard [4]. Worklists and the progression of radiotherapy orders should be transmitted in Digital Imaging and Communications in Medicine (DICOM) Unified Worklist and Procedure Step (UPS) [5] format. Radiation therapy dose calculation push workflow and radiation therapy pull workflow are explained in the UPS document. Treatment planning information should be stored in DICOM radiotherapy (DICOM-RT) object format and communicated using DICOM transfer protocols.

Interoperability also supports medical safety and operational efficiency. Particle therapy departments utilize many information systems. For medical safety purposes, patient demographic information and treatment data should be shared among these systems.

When radiation therapy is completed, radiation oncologists evaluate treatment results and follow up with patients. Therefore, the OIS needs to store clinical data, treatment plans, delivery dosages, radiation effects, and side effects to facilitate comprehensive treatment evaluation. These treatment data should be carefully maintained and summarized within a clinical database system.

Evaluating and improving the quality of radiation therapy requires complete information on cancer stage and treatment results. Hospital-based registries are a key tool. To determine the completeness of registry data, a nationwide cancer database is expected [12, 13]. The National Radiation Oncology Registry (NROR) [14] pilot program was presented as the basis for the creation of a nationwide electronic registry in the USA. This will be supported by an innovative information technology infrastructure that will maximize efficiency through the automated collection and electronic transfer of data. The NROR is supported by the Radiation Oncology Institute and the American Society of Radiation Oncology (ASTRO). Similar nationwide registries have also been planned and established in other countries. The automated collection and electronic transfer of data is a key issue to reduce physician workload and maximize efficiency. In Japan, the Japanese Society for Therapeutic Radiology and Oncology (JASTRO) [15] is planning to develop a similar radiation oncology database.

This registry should be developed with the careful selection of items. The items registered in the database should be standardized and anonymized to protect patient privacy. Moreover, security must be considered when determining the method to link patient data between the registry and hospital identification numbers.

In a radiation oncology system, multiple devices and subsystems are connected to each other. The transfer of information depends upon the coordination between devices. Further, the development of information systems requires standardization for rapid development and ease of integration. Standardization also facilitates preparation and reduces the test time. When standardized devices are used, it is much simpler to replace systems as needed and create request for proposal (RFP) documents.

There are several arguments in favor of standardization: