Search

A computed tomography (CT) based treatment planning system for total body irradiation (TBI) is presented and compared with the commonly practiced lateral treatment delivery. The TBI regimen has been proved to be an essential conditional regimen for patients undergoing bone marrow transplantation. The advantage of the TBI regimen with bone marrow transplantation (BMT) in hematological malignancies can be offset by toxicities arising from TBI in posttransplant complications. With the increasing survival rates, the evaluation of long‐term side effects and quality of life has become an important area of research interest. There have been several treatment techniques developed over the decades designed to achieve accurate dose delivery and dose homogeneity. This paper reports on the verification of the dose delivery for a basic lateral technique using thermoluminescent dosimeters (TLDs) placed in an anthropomorphic phantom and its correlation with CT‐based treatment planning. CT‐based treatment plans on several patients were used to evaluate the doses delivered to the whole body and critical organs. A large variation in doses delivered to the whole body was demonstrated, with some parts of the bone marrow failing to receive the prescribed dose and some critical organs, such as the lungs, receiving excessive doses. Placing the arms at the sides only partially compensates for the increased transmission of the lungs because the arms only shadow part of the lung. This study shows that CT‐based treatment planning for TBI provides precise and accurate dose calculations and allows for the correlation of clinical outcomes with the doses actually delivered to various organs. PACS numbers: 87.53.Dq, 87.66.Xa, 87.66.Sq

During the D–T operation of the International Thermonuclear Experimental Reactor (ITER), the dose inside ITER building is attributed to neutrons and gamma-rays streaming from various openings in the machine, whereas after shutdown, it is solely due to the decay gammas from activated components inside the building. In the present study, two cases of different geometrical arrangement are considered (Case A and Case C) in which the impact of the size of the opening of the NBI horizontal ports and presence of the NBI structure on the dose profiles everywhere in ITER building was studied and compared to the case (Case B) where all the horizontal ports are plugged. Contours and mapping of the dose rate profiles during operation, at shutdown, and at one-day, one-week, and one-month after shutdown, were generated for the three cases. Zone classification requirements for each hall/room and gallery of the building in terms of the maximum allowed exposure dose during operation and after shutdown were examined to identify where these requirements are met during ‘hands-on’ maintenance activities. It is shown that the requirements are satisfied at all times after shutdown in the halls above the ground, even during operation. For the conservative Case A, the dose rates are excessively high inside the equatorial NBI hall and inside the access halls above and below (divertor hall). In Case C, all the halls/vaults and galleries are accessible 1-week after shutdown, except inside the NBI hall whose dose rate (6.2 × 105 μSv h−1) exceeds the required zone classification (3–2 μSv h−1). All areas are accessible a week after shutdown in Case B which represents the building side away from the NBI ports. However, in all these cases, the accessibility criterion inside the rooms beneath the cryostat is not met at all times after shutdown due to the rather thin bottom bioshield (50 cm) which may necessitate some design changes.

The PhoStrip process is a biological-chemical process which removes phosphorus from wastewater. This article presents descriptions of the PhoStrip process, a plant-scale test of the process, the design of a 152,000 m3/d PhoStrip facility, and the start-up and initial full scale operation of the PhoStrip facility, all in association with the expansion of the Reno-Sparks Joint Water Pollution Control Plant in Nevada, USA. The PhoStrip process has demonstrated the capability of removing phosphorus to effluent levels of less than 0.5 mg/l at operating costs much less than operating costs associated with conventional chemical processes.