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Both neuropsychological tests of executive functioning and the Frontal Systems Behavior Scale (FrSBe) consistently predict instrumental activity-of-daily-living capacity. However, the nature of the predictive relationship between the FrSBe and neuropsychological tests of executive functioning has received limited attention. The current study was designed to assess the incremental validity of the FrSBe in predicting instrumental activity-of-daily-living functioning when added to comprehensive testing of executive functioning in a sample of 100 adult general neuropsychological referrals. A composite measure of executive test performance was calculated, and a family member completed the FrSBe and an instrumental activity-of-daily-living measure. Stepwise multiple regression analysis using the executive composite measure and the FrSBe accounted for 44% of the variance in instrumental activity capacity, and the addition of the FrSBe increased predictive ability by approximately 50%. The current results also indicate that FrSBe Scale E is more important as a predictor of instrumental activity capacity than the two self-regulation measures, Scale A and Scale D.

The current study was designed to evaluate the accuracy of the Minnesota Multiphasic Personality Inventory—2 (MMPI-2) and the Beck Depression Inventory (BDI) in determining the presence of depression in epileptic patients. A psychiatric diagnostic interview was used as an external criterion for the presence of depression. The participants were 61 patients undergoing presurgical evaluation for treatment of epilepsy at the epilepsy treatment center of a research medical center. The results of the present study indicate that the accuracy of assessment of depression in epilepsy with psychological tests varies with the depression scale or subscale used. The BDI performed in general more effectively as a diagnostic instrument than the MMPI-2. The results suggest that the latter test was negatively impacted by somatic content present in some scales and subscales.

The evaluation of current level of neuropsychological functioning is handicapped by the lack of validated actuarial methods for estimating premorbid intellectual functioning. The present study cross-validated and attempted to improve the one existing method of using demographic variables in a systematic way to predict WAIS Full Scale IQ (Wilson et al., 1978). A sample of 491 neurologically normal subjects was used. The results generally supported the IQ prediction equation, but did reveal systematic differences in accuracy of prediction and direction of prediction error for IQs in the high and low ranges. Also, a simpler IQ prediction formula that uses only years of education was developed and compared with the 5-variable Wilson et al. formula.

This study assessed the diagnostic utility of the Seashore Tonal Memory Test in detecting and localizing cerebral lesions. A group of 238 subjects with focal or diffuse cerebral lesions and a group of 112 normal comparison subjects were administered the Seashore Tonal Memory Test and the Halstead-Reitan Battery. All brain-damaged subgroups did significantly worse than the normal group on the Tonal Memory Test. Patients with right-hemisphere lesions were more impaired on this test than were those with left-hemisphere lesions. In contrast, Seashore Rhythm Test scores were not significantly different for groups with right- versus left-hemisphere lesions. Tonal Memory performance was not found to be related to more precise location of structural lesions within the right hemisphere. Step-wise discriminate function analyses indicated that the Tonal Memory Test adds to the Halstead-Reitan Battery in discriminating left-hemisphere from right-hemisphere lesions and that, for this purpose, it was a better discriminator than all but one of the individual tests currently in the battery.

Problems arise in designing treatment techniques involving two pair of adjacent opposing fields where machine limitations require the patient to flip from supine to prone positions. Mantle and para-aortic treatments, in particular, can create challenging problems because of changes in patient position, different SSD’s between adjacent fields, internal anatomical changes from supine to prone position, as well as field size and other treatment machine limitations. A simulator technique has been developed which takes cognizance of these limitations in specifying the gap between adjacent fields. It employs collinearity of the 50% decrement lines of adjacent-opposed field edges and the intersection of all four edges at an internal mid-plane match point. The technique maintains dose homogeneity and eliminates hot and cold triangles in the area of abutment. Simulation radiographs facilitate identification of collinearity with respect to a specific vertebra in the plane of abutment. In summary, this approach: Verifies abutment of coplanar fields by use of match film, improves isodose uniformity at mid-plane, evaluates dose distributions when abutment occurs at a point anterior or posterior to midline, prevents the possibility of spinal cord complications that might occur due to three field overlap.

A comparison was made of the relative power of a brief post-injury neuropsychological assessment and a brain-injury severity measure (PTA) to predict long-term cognitive outcome after severe brain injury. Subjects were 78 patients with severe brain injury. Regression analysis revealed that neuropsychological variables were as predictive of outcome as PTA. A combination of neuropsychological, brain-injury severity, and demographic variables predicted a substantial proportion of variance in both general cognitive ability and memory functioning at outcome. Removal of PTA from the set of predictors had only modest impact on predictive power, suggesting that, in the absence of accurate injury severity data, meaningful prediction about long-term cognitive outcome can still be made.

The efficacy of computer-assisted attention and memory retraining was evaluated with 15 severely head-injured patients. Training with selected exercises tailored to the individual's needs were provided from the THINKable program for up to 20 hours in both the attention and memory remediation modules. The experimental design evaluated outcome by juxtaposing multiple baseline procedures with a pre- and post-group comparison. Significant results were documented on the computerized tasks, psychometric measures and on patient and observer ratings of everyday behaviours of attention and memory.

Modern megavoltage radiation therapy is often provided by an isocentric treatment unit which rotates around the prone or supine patient. This method provides flexibility in the set-up and comfort for the patients. However, some lesions may be advantageously treated with the patients seated. The chair unit described provides for a great deal of flexibility in the set-up and treatment of seated patients including arc and full rotational therapy. The chair motion mechanism is completely below floor level facilitating easy access to the patient. We find it particularly useful for head and neck treatments where individually tailored fields are defined by Cerrobend shields. These patients are most often treated with a horizontally directed beam. A bite block is frequently used to ensure reproducible positioning of individual patients (Karzmark et al., 1975).The treatment unit used with the chair, a Varian Clinac 10 (Karzmark et al., 1973), is not isocentrically-mounted but moves vertically and rotates about a horizontal axis perpendicular to the beam axis. Figure 1, a scale model, illustrates the geometry and depicts the basic motions of the chair and Clinac by arrows. This particular combination of motions provides a co-ordinate system similar to that available in the conventional isocentric system. Figure 2 illustrates the relationship between the translation and rotation axes for the isocentric system (Fig. 2A), in contrast to the chair-treatment unit described herein (Fig. 2B and c).

An electron therapy technique is described for treating large field superficial lesions, particularly mycosis fungoides, which has been in use for several years at Stanford Medical Center (Karzmark et al., 1960). An X-ray linear accelerator has been modified to permit convenient, rapid and routine conversion to this treatment modality with minimum interference to a large supervoltage therapy programme. Information is presented on treatment geometry, electron/X-ray conversion features, dosimetry and treatment planning.The system can be adapted to different accelerators, although it lends itself particularly well to the isocentric geometry found on many linacs, and results similar to those described would probably be obtained with existing 4 MeV equipments. The use of carbon decelerator-scatterers (Szur et al., 1962), could extend the technique to somewhat higher energy accelerators as well as permitting a wider choice of depth dose characteristics.

This report concerns certain aspects of radiation safety for megavoltage electron accelerators used for both X-ray and electron therapy, particularly linear accelerators. Such accelerators pose a specific radiation hazard. The hazard arises in ensuring that the devices and procedures required for the large reduction in electron beam current associated with the electron therapy modality are sufficiently rigorous, both technically and operationally, to render it exceedingly unlikely for patients to be exposed to excessive electron doses as a result of a technical failure and/or an operational inadvertence. This note describes some of the radiation safety features of a 5 MeV accelerator used routinely for both X-ray and electron therapy. Included are a description of the X-ray/electron therapy changeover procedure, the radiation monitoring system, the accelerator electron gun design, data on our relevant failures, the use of secondary emission monitors, beam loading and a number of peripheral considerations relating to radiation safety.

Narrow and broad-beam absorption coefficients were evaluated for lead, steel and concrete using the primary X-ray beam from a 6 MeV linear accelerator. For narrow beams the absorption coefficients in cm-1are 0·50, 0·31, and 0·084 for lead, steel and concrete respectively, while the corresponding tenth-value thicknesses are 4·6, 7·5 and 27·4 cm respectively. For broad beams the absorption coefficients in cm-1are 0·41, 0·23 and 0·066 for lead, steel and concrete respectively, while the corresponding tenth-value thicknesses are 5·7, 10·0 and 34·8 cm respectively. Measurements were made over six tenth-value thicknesses of lead and four to five for steel and concrete. Frequently, leakage and unwanted scatter are larger than the transmitted primary intensity by factors of 5 or greater. The methods of preferentially shielding and discriminating against these spurious components and the corrections for them are described. The attentuation curves, the experimental arrangements and the problems of measurement are discussed.

The measurements reported are for leakage radiation emerging from the X-ray target housing of a 6 MeV linear accelerator. Film dosimetry was extensively used to study leakage radiation and served to guide improvements in X-ray head shielding. An ionisation chamber study of the leakage component confirmed the film results and provided intensity profiles in three orthogonal planes passing through the target. The ionisation chamber was also used to measure leakage radiation attenuation and to establish a profile of the useful beam and the penumbral region. For one representative operating condition the leakage and total scatter magnitudes rarely differed by more than a factor of 2 in the therapy room.

The measurements reported are for secondary radiation scattered from either a Presdwood phantom or a concrete barrier. The magnitude, angular distribution and attenuation characteristics of these secondary radiations are discussed. The relative dose from radiation scattered by a Presdwood phantom was evaluated at 1 m from the phantom. Expressed as a percentage of the dose at the centre of the phantom it varied from 0·04 per cent at 135 deg. to 0·8 per cent at 15 deg. Expressed as a tenth-value thickness the attenuation thickness for this scattered radiation in concrete varied from 14·7 cm at 135 deg. to 33·3 cm at 15 deg. The attenuation of 90 deg. scatter was also investigated for Presdwood, steel and lead. The 90 deg. scatter has a monochromatic equivalent energy of slightly less than 500 keV. The intensity and angular distribution of scatter from a concrete barrier was examined for both 90 and 60 deg. incidence of the primary beam. For these measurements the scattered dose at 1 m did not exceed 0·25 per cent of the dose maximum just below the barrier surface for a 48 × 48 cm field.

A description is given of a new and compact megavoltage therapy system which combines a cantilevered treatment couch with an isocentrically mounted accelerator capable of rotating completely around a recumbent patient. In addition, provision is made for therapy techniques which require patient rotation.This linear accelerator system introduces a new standard of compactness and flexibility as related to patient treatment. The overall height of the accelerator is less than 240 cm while a 100 cm FSD is retained. The patient support assembly includes a plastic portal device for irradiation from beneath the couch, three-dimensional positioning of the patient, and snap-off wheel assemblies which enable the patient to be lowered to floor level on an electrically operated pedestal for large field techniques. These features ensure rapid, precise, and consistent patient set-up procedures. Representative techniques are illustrated. Use of the actual treatment couch for patient transportation is an operational convenience. The application of this accelerator system for diagnostic radiography is discussed.Physical measurements indicate a high degree of beam flatness and a surface dose of less than 20 per cent of the maximum which occurs at about 15 mm depth. High X-ray intensity permits large FSD techniques.Approximately 600 watts of electron beam power can be made available through the X-ray beam defining system by a simple conversion. Some characteristics of the electron beam are discussed to enable evaluation for sterilisation and radiobiological applications.

A number of accessories have been developed to provide immobilization of the head during radiation therapy. These include casts and shells, head clamps arranged to contact the chin, skull side, forehead, glabella or auditory meatus as well as sterotaxic devices (Berman, 1957; Bottrill, Rogers and Hope-Stone, 1965; Hutchinson and Evans, 1965; Kirsh and Womack, 1966; Lee, 1969; Mallion and White, 1968; New, 1962; Perez-Tamayo and Seibert, 1963; Pochaczevsky and Levine, 1971; Ridings and Marvin, 1974; Roswit, Reid and Malsky, 1957; Sandberg and Yules, 1968; Sargent and Posnikoff, 1965; Son, 1968; Von Arsdale and Greenlaw, 1971; Von Essen, Agostinelli and Kligerman, 1970). The “bite-block” described here† incorporates an individual patient's dental impression on which he bites down to provide head immobilization and reproducible positioning during radiation therapy. We have used this head immobilization technique for almost two decades, originally with patients sitting on a treatment chair for horizontal beam treatments but later for supine patients treated isocentrically. The bite-block has been cited earlier in several clinical applications (Bagshaw et al., 1965; Hanks, Bagshaw and Kaplan, 1969; Kaplan and Bagshaw, 1957; Thompson, Scotte Doggett and Bagshaw, 1970), but its newer versions and details of fabrication have not been presented hitherto. Verification films taken during a course of therapy confirm the reproducibility of set-up using this accessory. More recently, the bite-block has been employed for head immobilization in conjunction with computerized transverse axial tomography using an EMI scanner.

The ideas, parameters, and dose calculations relating to treatment planning for radiotherapy are basically simple. However, the advent of megavoltage radiation therapy and new treatment techniques have acted to expand and complicate early methods and often each institution has adopted its own conventions and symbols. At present, therefore, communication is hindered by the lack of an agreed notation; a significant difficulty exists in the retrospective interpretation of patient treatment records and there is increased need for rapid, accurate dose calculations where the introduction of high-output megavoltage sources has rapidly expanded patient loads. In an effort to simplify records and dose calculations, the notation and formulae presented here were adopted after an examination of our existing system, a retrospective study of our treatment records and a survey of the radiotherapy literature. The system described evolved from a simpler version which was used for a number of years.The system shown in Table I consists of a set of symbols (capital letters with one exception) to define quantities useful in radiotherapy, and an accompanying set of subscripts (lower-case letters) which may be added to restrict or further define the quantities represented by the symbols. The choice of a particular letter has been guided by present usage, a desire to include a mnemonic aid, and by the cohesiveness, clarity and lack of conflict which ensues when the symbols and subscripts are combined and used. An effort has been made in the definitions to achieve maximum generality while retaining sufficient rigour to avoid ambiguity.

A detailed observation of patient treatment using a linear accelerator was undertaken to assess the potential time savings from automation. The total time per treatment has been categorized in terms of set-up time, beam-on time and time devoted to miscellaneous tasks. Based on a series of 179 treatment sessions, a mean value of 9·8 minutes was observed for the total time per treatment with an allocation of about 20 per cent to beam-on time, 50 per cent to set-up and 30 per cent to miscellaneous tasks. A dose-rate of 250 rads per minute at 1 m was employed.

It is generally recognized that a major problem in the radiation therapy of cancer is failure to control the local tumour (Suit, 1969). This failure is principally due to the inability to deliver a lethal dose to the tumour while sparing the surrounding normal tissue (Paterson, 1948). Future progress in solving this problem will come from improvements in tumour localization and dose distribution over the target volume. The dose distribution is influenced by immobilization error and patient movement. It is with this that we are concerned in this note.

LITHIUM fluoride powder is now being used extensively for thermoluminescent dosimetry of ionizing radiations because of its good tissue-equivalence with respect to photon energy, and its reported absence of fading1–3. We have found hitherto unreported changes of response with time, predominantly manifested by fading of the read-out by some 10–20 per cent at 3 weeks after irradiation, followed by a tendency to increase towards the initial value at 6–8 weeks. This fading can cause difficulties in practical use unless care is taken to read-out specimens at the same time after irradiation. The fading reported here is other than any occurring in the first 24 h.

When a high patient load threatens the capacity and treatment precision of a therapy department, it is appropriate to consider the benefits of simulation and the merits of special as opposed to general-purpose design simulators.Although traditionally a portion of the schedule of the treatment unit is devoted to “setting-up” new patients, it often makes economic sense in a burdened department to transfer this work to simulation units. Such simulators use diagnostic quality radiographic generators which produce better films than are possible with megavoltage therapy beams and, in addition, permit fluoroscopy. The two major set-up functions that a simulator provides are: (1) tumour localization and, after treatment planning, (2) treatment verification using films of each field of the simulated treatment. In our view, tumour localization—the accurate specification of tumour location, dimensions and shape relative to external landmarks—involves the most essential use of a simulator that cannot be adequately provided using a megavoltage treatment unit or a conventional diagnostic X-ray unit (Gardner, Bagshaw, Page and Karzmark, 1971).

The tools of contemporary radiology are becoming increasingly complex. In order to exploit their capabilities fully and not become slaves to their frailties, adequate maintenance must be provided. We have adopted a programmed preventive maintenance system, using our own staff, which ensures fewer interruptions and better performance. In addition the staff concerned add to the research capability of the department while continued improvement results from their intimate contact with the equipment. The system described below can be adopted with minimum effort, and requires only small amounts of readily available materials. It was developed when we were unable to locate a commercial system of sufficient flexibility, generality and ease in use to meet our needs.

Treatment planning for moving field therapy using X and ? rays has been greatly simplified by the use of the tissue-air ratio, sometimes designated the tumour-air ratio (Johns, Whitmore, Watson, and Umberg, 1953; Johns, 1961). The tissue-air ratio, TAR, is defined (Brit. J. Radiol., Suppl. 10, 1961) as the ratio of the dose (or dose-rate) at a point in tissue to the dose (or dose-rate) at the same spatial point in air, where both measurements are made under conditions of electronic equilibrium. However, the ICRU has recently recommended (Report lOd, 1963, p. 8) that calibrations be made at a standard point in a phantom rather than in air. Such phantom measurements are less likely to be influenced by electron contamination or by soft radiation from collimating systems and are particularly relevant to megavoltage radiations where exposure measurements are invalid. Meredith (1963) has shown that a phantom calibration procedure can improve the accuracy of dosimetry at therapeutically important depths, particularly for lower energy radiations.

In relating the output of a radiation source to the dose delivered to a specific site in an irradiated tissue, it is convenient to use a dose-normalisation factor. This is usually achieved by specifying the dose in rads at a convenient and unambiguous point in tissue, normalising this dose to 100 per cent and relating the dose at other sites to this value.

In most external beam radiotherapy, it is customary to establish the treatment field size by a beam of light whose edges approximate in position the edges of the radiation field. Problems arise in relating such an optically defined geometric specification of field size to a dosimetric specification relating to a particular isodose contour, a parameter more relevant to radiotherapy. Since different conventions for specification of field size are employed by different treatment centres geometrically identical fields may be in poor dosimetric agreement. In our opinion, the differing conventions for field-size specification that are in use tend to increase the likelihood of dosimetric error, foster ambiguity and impede communication and the free flow of dosimetric information.

The scheduling of radiological equipment maintenance has become increasingly difficult as equipment has grown more complex and more heavily used. At the same time, licencing, accrediting and regulatory agencies increasingly require archival records of maintenance procedures performed on radiological as well as other equipment.

The use of wedge filters in radiation therapy is well established. With the recent increase in the use of megavoltage radiation equipment, there has been a corresponding increase in the use of wedge filters, particularly in the U.S.A. Agreed conventions for specification of wedge field size, wedge angle, wedge isodose normalization, wedge factor and wedge isodose display therefore become increasingly important to both user and manufacturer. The intent of this letter is to suggest that such conventions be adopted.