A design study for a 'spiral staircase' ionization chamber for the quality control of electron beams.

In order to verify that the energies of electron beams used for external beam therapy remain constant, IPEM 81 recommends a constancy check based on the ratio of ionization chamber measurements at two depths along the central axis. Such measurements for a range of electron energies can be a time consuming process. The purpose of this study was to design a device that would use several ion chambers simultaneously to measure electron depth dose curves, and hence the electron energy. A design was developed for a device consisting of ten independent ionization chambers, shaped and arranged in a solid phantom like the steps of a spiral staircase, the axis of the staircase being coincident with the axis of the electron beam. Measurements were carried out to test the design of individual chambers and to optimize the radius of the spiral and both the depth intervals and the lateral spacing between adjacent chambers. For ranges of electron energy from 6-12 MeV and 12-20 MeV the radii of the spirals needed were found to be 36.5 mm and 30.9 mm, the angular separations between edges of the chambers were 52 degrees and 30 degrees and chamber depths were found to be 10, 15, 20, 25, 30, 35, 40, 45, 50, 55 mm and 20, 40, 45, 50, 55, 60, 65, 70, 75, 80 mm, respectively.

IPEM guidelines on dosimeter systems for use as transfer instruments between the UK primary dosimetry standards laboratory (NPL) and radiotherapy centres.

United Kingdom dosimetry codes of practice have traditionally specified one electrometer for use as a secondary standard, namely the Nuclear Enterprises (NE) 2560 NPL secondary standard therapy level exposure meter. The NE2560 will become obsolete in the foreseeable future. This report provides guidelines to assist physicists following the United Kingdom dosimetry codes of practice in the selection of an electrometer to replace the NE2560 when necessary. Using an internationally accepted standard (BS EN 60731:1997) as a basis, estimated error analyses demonstrate that the uncertainty (one standard deviation) in a charge measurement associated with the NE2560 alone is approximately 0.3% under specified conditions. Following a review of manufacturers' literature, it is considered that modern electrometers should be capable of equalling this performance. Additional constructural and operational requirements not specified in the international standard but considered essential in a modern electrometer to be used as a secondary standard are presented.

Compression of the biceps-brachialis compartment after trivial trauma.

We report a case of post-traumatic compartment syndrome of the biceps-brachialis compartment after a minor injury. The condition is well recognised after a drug overdose, but surgeons should be aware that a compartment syndrome may also be caused by apparently trivial trauma, and that it may develop in regions other than the anterior compartments of the leg and forearm.

Spontaneous regression of a desmoid tumour.

A 15-year-old girl presented with a very large desmoid tumour in her buttock; it extended into the pelvis and thigh and would have required hindquarter amputation for its removal. This was not performed and the tumour underwent spontaneous regression. Fourteen years later the patient is alive and well. The suggestion is made that in some cases a more expectant approach to treatment might be justified for what is essentially a non-malignant condition.

External fixation of Colles' fractures. An anatomical study.

In a prospective, controlled study 58 patients aged under 60 years with Colles' fractures were treated either by a forearm plaster or by the application of an external fixator. In 94% of those treated by a fixator it was possible to insert the distal pins of the frame into the fracture fragment, the fixation obtained being sufficient to forgo additional splintage. The external fixator proved more effective at holding the manipulated position, and the radiological loss of position during fracture union was minimal compared with that seen in patients treated in plaster.

The unstable Colles' fracture.

One hundred and twenty-one displaced Colles' fractures were assessed radiographically until union. An acute loss of position occurred during the first week of splintage, necessitating re-manipulation in six fractures. In the remaining 115 fractures whose position had been retained after one week, chronic instability led to a mean increase of 8.22 degrees dorsal angulation, a mean loss of 5.61 degrees radial angle, and 3.26 mm radial shortening. The extent to which the chronic collapse of radial angle and length occurred was determined solely by the initial deformity and was not related to either intraarticular involvement or the presence of radiographically visible comminution. However, the absence of radiographically visible comminution of the dorsal radius did confer stability against mal-union in dorsal angulation.

Late rupture of the extensor pollicis longus tendon: the case against attrition.

The authors report the case of a 23-year-old man who sustained ipsilateral volar Barton's and scaphoid fractures which were complicated by a late rupture of the extensor pollicis longus tendon. The anatomy of the injury precluded attrition as the cause of the tendon rupture and the alternative theory of ischaemic rupture is examined. Clinicians should be aware that injuries other than the Colles' fracture may be complicated by rupture of extensor pollicis longus.

Mal-union and dysfunction in Colles' fracture.

Wrist function was assessed between one and three years after injury in patients who had suffered Colles' fractures. Both the range of wrist flexion and the strength of grip were found to be deficient. The loss of power in gripping was found to correlate with mal-union affecting the coronal and sagittal inclination of the articular surface of the radius.

Simultaneous Colles' and scaphoid fractures: treatment by combined internal and external fixation.

The authors present the case of a young woman who sustained ipsilateral scaphoid and Colles' fractures that were treated by a combination of Herbert screw fixation of the scaphoid fracture and external fixation of the colles' fracture. This form of treatment provides optimal conditions for both the early return of wrist function and for the maintenance of the manipulated position.

External fixation and recovery of function following fractures of the distal radius in young adults.

The functional recovery from Colles' fracture was studied prospectively over a 1-year period in 106 patients randomized to treatment by plaster or external fixation. Although external fixation allows immediate mobilization of the wrist and leads to a much better anatomical result, these factors did not permit any improvement in the wrist's early functional recovery. One year following injury the grip strength of the fixator-treated group was significantly superior to that of the plaster-treated patients.

New problems in old bones: closed nailing of the shaft of the femur.

Closed medullary nailing is now established as a routine treatment of fractures of the shaft of the femur. However, the quality of the bone in elderly patients is such that serious technical difficulties may arise during the operation. Three typical cases illustrate the problems that may occur and point the lesson that closed nailing in the elderly ought not to be undertaken by the inexperienced surgeon.

The use of gentamicin-PMMA chains in abdominal surgery: a pilot study of prophylaxis against wound infection.

A prospective study was carried out to examine the effectiveness of gentamicin-impregnated polymethylmethacrylate beads in the prevention of wound sepsis after gastro-intestinal surgery. The beads were laid in the abdominal and perineal incisions (61 wounds) of 55 patients at the end of the operative procedures, and were withdrawn in stages from the fifth post-operative day. This method of administration results in a sustained high antibiotic concentration in the wound with low serum and urine concentrations, thus eliminating the dangers of gentamicin toxicity. Wound infection occurred in only 1 instance, a favourable result when compared to historical controls. It is suggested that further controlled studies of this method of topical prophylactic antibiotic administration are indicated.

Irreducible dislocation of the distal radioulnar joint.

Although dislocation of the distal radioulnar joint is commonplace in association with fractures of the radial shaft, irreducible dislocation has previously been considered to be rare. In the only three previously reported cases the tendon of the extensor carpi ulnaris blocked reduction of the distal radioulnar joint in Galeazzi injuries. The cases presented in this report show that other tendons may be involved, and that the injury may occur even when the ulna is broken. It is likely that the injury described is more common than is realized and is usually overlooked.