Quantitative comparison between the commercial software STRATOS(®) by Philips and a homemade software for voxel-dosimetry in radiopeptide therapy.

BACKGROUND: Targeted radionuclide therapy is a rapidly growing modality. A few commercial treatment planning systems are entering the market. However, some in-house systems are currently developed for a more flexible and customized dosimetry calculation at voxel-level. For this purpose, we developed a novel software, VoxelMed, and performed a comparison with the software STRATOS. METHODS: The validation of both of them was undertaken using radioactive phantoms with different volume inserts. A cohort of 10 patients was also studied after a therapeutic administration of (177)Lu-labelled radiopeptides. The activity, number of disintegrations, absorbed dose and dose-volume histogram (DVH) were calculated for the phantoms and the kidneys in patients, which were the main critical organs at risk in this study. RESULTS: In phantoms the absorbed doses computed with VoxelMed and STRATOS agree within 5%. In patients at the voxel-level the absorbed dose to kidneys (VoxelMed: mean 0.66 Gy/GBq) showed a limited difference of 5%, but with a remarkable range (-40%, +60%) between the two software packages. Voxel-dosimetry allows to estimate the dose non-homogeneities in volumes, which may be evaluated through DVHs. CONCLUSION: This study demonstrates that a fully 3D voxel-dosimetry with multiple SPECT images is feasible by using home-made or commercial software package and absorbed dose results obtained are similar. The main difference between the studied tools was observed in the activity integration method (effective vs physical half-time to time activity curve tail). We believe that an effective half-time integration method produces a more accurate approximation of clinical uptake and resultant dosimetry.

Response of the flexion-relaxation phenomenon relative to the lumbar motion to load and speed.

STUDY DESIGN: Nonrandomized control trial. OBJECTIVE: To determine if the variations of speed and loading conditions during trunk flexion-extension could influence the times of occurrence and disappearance of the electrical silence of the erector spinae muscles, the degrees of lumbar flexion at those instants, and the relative lumbar motion time. SUMMARY OF BACKGROUND DATA: It has been suggested that varying either the speed of movement or the load on the trunk during trunk flexion-extension movements may influence the flexion-relaxation phenomenon or the kinesiologic data. However, no study dealt with the simultaneous effect of the speed of movement on the spine rhythm and on the occurrence of the electrical silence of the erector spinae. METHODS: A total of 22 pain-free volunteers performed a series of trunk flexion-extension movements varying the speed and load. The motion of the lumbar spine ( degrees ) and the integrated electromyography (microV) of erector spinae muscles were simultaneously recorded. Two measures were calculated: the percentage of the maximum lumbar spine flexion at the instants when changes of electrical activity represented the beginning and end of the electrical silence and the relative lumbar spine motion time during trunk flexion and extension movements. RESULTS: The increase in speed of movement significantly increased the relative lumbar flexion time and significantly reduced the relative lumbar extension time (t = 2.49 and t = 2.25, P < 0.05); furthermore, it significantly delayed the appearance of the electrical silence in the range of flexion (t = 3.52, P < 0.01). There was no significant effect from a change in load. CONCLUSIONS: The relative spine motion time differed depending on the direction of movement, being longer during trunk flexion and shorter during extension. The increase in speed of movement produced greater differences in the relative time between trunk flexion and extension; furthermore, it delayed the appearance of the electrical silence of the erector spinae muscles in the range of flexion.

Software tools for using a personal computer as a timer device to assess human kinematic performance: a case study.

Frequently, the assessment of the physical condition of a sportsman depends on the evaluation of different tests, based on biomechanical performance. The data acquisition in these tests is usually hand made, because its automatization is difficult. But when movements are constrained by means of their specific nature, simple tools can be used to achieve that data acquisition. In this paper, a simple and inexpensive system is described to make use of the timing capabilities of a personal computer (PC) to use it as a timer, with applications in biomechanics and sport training. The data acquisition method is based on a PC that, using a specific programming dealing with event timing, gets signals through the printer port, from a receptor device that detects cuts in an infrared cell beam. Low level procedures are provided that can be used in higher level algorithmic designs, problem dependent, to build specific systems. The case of the evaluation of the Wingate Anaerobic Test is discussed.

Muscle activity in upper and lower rectus abdominus during abdominal exercises.

OBJECTIVE: To compare the intensity of the upper versus lower rectus abdominis (RA) muscle activity provoked by each of two different abdominal exercises and to contrast the intensity of contraction elicited by two different abdominal exercises on each RA muscle portion. DESIGN: Nonrandomized control trial. SETTING: Kinesiology laboratory in a university medicine faculty. PARTICIPANTS: Convenience sample of 33 healthy volunteers. Subjects who had practiced endurance or strength training activities (1.5 hours 3 days a week for 3 years) and those who had not accomplished that criterion comprised a high and a low physical activity group, respectively. Each of these two groups was divided by the ability to perform the exercises into two subgroups: correct and incorrect performers (cp, ic). MAIN OUTCOME MEASURE: Average surface iEMG was compared between upper and lower RA and on each muscle portion performing curl-up (CU) and posterior pelvic tilt (PT) exercises. The coefficient of variation, a two-way analysis of variance, and the t test were calculated. RESULTS: The upper RA showed significantly greater activity during performance of CU exercise by the cp subgroups of both high (t = 2.14302, 95%) and low (t = 2.35875, 95%) activity groups. Only the cp subgroup of the high activity group showed that PT was significantly more strenuous than CU exercise on lower RA (t = -2.06467, 95%). CONCLUSIONS: Among correct performers, CU produces greater activity on upper RA. For persons who have a high level of activity, PT is more strenuous than CU on lower RA. Among incorrect performers, either exercise indistinctly activates the muscle portions.