PubMed Health⌕ Search
Home/Archive/PubMed

PubMed · 7607943

Maintaining accuracy in stereotactic radiosurgery.

B J Gerbi·D M Roback·S D Humphrey·W A Hall
View original source ↗Export metadata ↓

Abstract

PURPOSE: To provide the manufacture's specification for the base phantom of a commercially available stereotactic radiosurgery system so that its accuracy can be confirmed, and to describe a calibration device that allows the accuracy of the base phantom to be verified quickly and on a routine basis. Modifications to the target pointer system that make matching the pointer tips easier and less likely to damage the pointer tips are also described. METHODS AND MATERIALS: In stereotactic radiosurgery, spatial accuracy is the key factor for successful dose delivery. With some commercially available systems, this accuracy depends on the accuracy of the base phantom coordinate system, how closely the tip of the target pointer can be matched to the tip of the base phantom pointer, and how accurately the coordinates set on the isocentric subsystem match those set on the base phantom. Two major problems, usually overlooked when evaluating system accuracy are, first, the base phantom, which establishes the stereotactic coordinate system, is assumed to be completely accurate. This is a dangerous assumption because the base phantom is used frequently for routine patient treatments and for standard quality assurance tests. To exacerbate the problem, no independent device is provided with stereotactic systems to check the accuracy of the base phantom. Second, the accuracy of the isocenter coordinates set on the head support stand depends upon how closely the target pointer and the base phantom pointer can be aligned. The hardware provided with the system is difficult to use and easily leads to damage of the pointer tips. RESULTS: In this work, we provide the manufacturer's specifications for a popular stereotactic system, describe a device that can be used to check quickly and easily the accuracy of the base phantom, and describe a modification to the transfer pointer system that allows the pointer tips to be more easily aligned with reduced possibility of damage to the pointer tips. CONCLUSION: The methods and apparatus described in this paper should be useful to anyone using a base phantom for testing radiosurgery accuracy.

Explore related subjects

Equipment DesignQuality Assurance, Health CareRadiosurgeryJournal ArticleResearch Support, Non-U.S. Gov't

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

B J Gerbi, D M Roback, S D Humphrey, W A Hall. 1995-07-15. Maintaining accuracy in stereotactic radiosurgery.. https://doi.org/10.1016/0360-3016(94)00408-d

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

PubMed2007

Dual-trap technique for reduction of low-frequency noise in force measuring optical tweezers.

High-resolution long-time force measurements by optical tweezers are often limited by low-frequency (1/f) noise. A dual-trap technique is presented that can reduce such noise in the force signal. It incorporates a second trap (a reference trap) that probes the noise in the system and it is based upon the assumption that the low-frequency parts of the noise from the two traps are correlated. A subtraction of the low-frequency signal from the reference trap from the signal from the force measuring trap will therefore yield a net signal that is significantly less influenced by noise. It is shown that this dual-trap technique can reduce the noise in the force signal up to 60% depending on detection bandwidth.

Equipment Design↗
PubMed2007

Optimization of doses received by the hospital staff and the members of the family of patients undergoing 111In-DTPA-D-Phe1-Octreotide therapy.

According to the Euratom Directives (96/29, 97/43), the doses received by the workers as well as the family of patients and third persons during medical exposures, should conform to the dose constraint levels (DCLs), established by the authorities for each group in the context of optimisation. This study deals with the implementation of a radiation protection protocol, concerning the aforementioned group members for patients undergoing treatment with 111In-DTPA-D-Phe1-Octreotide, after intra-arterial infusion. It is shown that by applying this protocol the annual doses to the medical and technical staff are considerably reduced and remain below the established DCLs. Following the post-release behaviour instructions given to the patient, doses to the family and third persons may be kept lower than the corresponding DCLs provided by the National Regulations.

Equipment Design↗
PubMed2007

In vivo myograph measurement of muscle contraction at optimal length.

BACKGROUND: Current devices for measuring muscle contraction in vivo have limited accuracy in establishing and re-establishing the optimum muscle length. They are variable in the reproducibility to determine the muscle contraction at this length, and often do not maintain precise conditions during the examination. Consequently, for clinical testing only semi-quantitative methods have been used. METHODS: We present a newly developed myograph, an accurate measuring device for muscle contraction, consisting of three elements. Firstly, an element for adjusting the axle of the device and the physiological axis of muscle contraction; secondly, an element to accurately position and reposition the extremity of the muscle; and thirdly, an element for the progressive pre-stretching and isometric locking of the target muscle. Thus it is possible to examine individual in vivo muscles in every pre-stretched, specified position, to maintain constant muscle-length conditions, and to accurately re-establish the conditions of the measurement process at later sessions. RESULTS: In a sequence of experiments the force of contraction of the muscle at differing stretching lengths were recorded and the forces determined. The optimum muscle length for maximal force of contraction was established. In a following sequence of experiments with smaller graduations around this optimal stretching length an increasingly accurate optimum muscle length for maximal force of contraction was determined. This optimum length was also accurately re-established at later sessions. CONCLUSION: We have introduced a new technical solution for valid, reproducible in vivo force measurements on every possible point of the stretching curve. Thus it should be possible to study the muscle contraction in vivo to the same level of accuracy as is achieved in tests with in vitro organ preparations.

Equipment Design↗