Dwell time verification in brachytherapy based on time resolved in vivo dosimetry.

PURPOSE: This paper presents a method to verify dwell times during High Dose Rate (HDR) Brachytherapy (BT) by means of in vivo dosimetry (IVD), and reports on an afterloader's stability in dwell time control. METHODS: In vivo dosimetry was performed during 20 HDR prostate cancer treatments using a point detector based on a radio-luminescence crystal (Al2O3:C) coupled to a fiber-optic cable. The dose rate was recorded at either 10 Hz or 20 Hz during the treatments. The "time of transit" when the source moved between two dwell positions was identified using the difference in count rate between two measurements. The dwell times were then determined by subtracting two adjacent times of transit. The measured dwell times were matched with the planned dwell times and categorised into two groups: Dwell times matching a single dwell position (identified) and dwell times matching the sum of multiple dwell positions (unidentified). Deviations between measured and planned dwell times were calculated for the identified dwell positions. RESULTS: A total of 3518 dwell positions were analysed. The amount of identified dwell positions were 82%, which increased to 89% if the short dwell times (<1 s) were omitted in the analysis. The largest deviation was -0.4 s seen for a single dwell position, and in 97.1% of the cases, the deviations were <0.15 s. CONCLUSION: The dwell times in BT are well controlled by the afterloader. It is shown that IVD facilitates the detection of dwell time offsets that could have a clinical impact.

Effect of changing tumor oxygenation on glycolytic metabolism in a murine C3H mammary carcinoma assessed by in vivo nuclear magnetic resonance spectroscopy.

The rate of conversion of D-[1-(13)C]glucose into [3-(13)C]lactate (apparent glycolytic rate) has been determined in C3H murine mammary carcinomas in vivo using tumor-selective (13)C nuclear magnetic resonance spectroscopy with (1)H-(13)C cross-polarization. Under conditions of acute hypoxia induced by breathing carbon monoxide at 660 ppm, the apparent glycolytic rate was 0.0239 +/- 0.0019 min(-1). The proportion of (13)C label incorporated into [4-(13)C]glutamate (measured in tumor extracts) was 25-fold lower than that incorporated into [3-(13)C]lactate, reflecting a very limited oxidative metabolism during this hypoxic episode. For animals breathing air or carbogen (95% O(2) + 5% CO(2)), the calculated glycolytic rates were correspondingly lower (0.0160 +/- 0.0021 min(-1) and 0.0050 +/- 0.0011 min(-1), respectively). Although (13)C labeling of glutamate at C4 was still an order of magnitude lower than that for lactate at C3 (11-fold for air and 9-fold for carbogen), these ratios did show a greater degree of oxidative metabolism than that seen in animals breathing carbon monoxide at 660 ppm. The marked difference in apparent glycolytic rate for this tumor model between well-oxygenated and hypoxic conditions demonstrates a substantial Pasteur effect (inhibition of glycolysis by oxygen). Dynamic (13)C nuclear magnetic resonance spectroscopy provides a noninvasive estimate of tumor glycolysis that can be used to evaluate the relationship between oxygenation and energy metabolism, and this has potential consequences for the sensitivity of hypoxic cells to treatment and their ability to promote angiogenesis.

[Motor function in children with clubfoot. A descriptive, controlled study]. / Motorik hos klumpfodsbørn. En deskriptiv, kontrolleret undersøgelse.

The purpose was to assess the motor function and morphological conditions in children with clubfoot compared with children without this deformity. Functional tests, structured interviews and clinical examinations were used. Seven boys with clubfoot treated in neonatally at Herlev Hospital in 1987/88 and fourteen matched children without deformity were included. Balance and plasticity in the ankle joints were reduced as compared with expected age-related level of motor function and to the control group. After physical activity pain in the legs was more frequently reported by the clubfoot children. Muscular dysplasia was seen in all clubfoot legs. Passive movements in affected ankle joints were reduced in plantar flexion, dorsal flexion and eversion. The differences were statistically significant. The conclusion was that motor function in clubfoot children is developed to a lower level than in children without clubfoot.

[Intensive dynamic back exercises for patients with chronic low back pain. A controlled study]. / Intensiv dynamisk rygtraening til patienter med kronisk laenderygsmerte. En kontrolleret undersøgelse.

The effect of intensive dynamic back extensor exercises for patients with chronic low back was investigated in a controlled clinical trial where the patients underwent a three months intensive training program a total 30 sessions. The 105 patients were divided into three groups: a treatment group, an alternative group which underwent 1/5 of the treatment group's exercise program per session, and an alternative group in which the treatment consisted of thermotherapy, massage and mild exercise. Regardless of whether the outcome of treatment is assessed qualitatively or quantitatively, a statistically significant, favourable difference was found between the results for the treatment group and those for the alternative groups. The therapy was found to be without risk, but patients with clinical signs of current lumbar nerve root compression or radiological signs of spondylolysis or halisteresis of the column were excluded from the study. The authors recommend the introduction of this form of treatment as a general offer in the primary and secondary health sector. Back exercises can advantageously be conducted in a group; thus, the resources required for this treatment do not differ significantly from those required for many of the other forms of treatment generally employed, which often require individual attention.

Bladder dose accumulation based on a biomechanical deformable image registration algorithm in volumetric modulated arc therapy for prostate cancer.

Variations in bladder position, shape and volume cause uncertainties in the doses delivered to this organ during a course of radiotherapy for pelvic tumors. The purpose of this study was to evaluate the potential of dose accumulation based on repeat imaging and deformable image registration (DIR) to improve the accuracy of bladder dose assessment. For each of nine prostate cancer patients, the initial treatment plan was re-calculated on eight to nine repeat computed tomography (CT) scans. The planned bladder dose-volume histogram (DVH) parameters were compared to corresponding parameters derived from DIR-based accumulations as well as DVH summation based on dose re-calculations. It was found that the deviations between the DIR-based accumulations and the planned treatment were substantial and ranged (-0.5-2.3) Gy and (-9.4-13.5) Gy for D(2%) and D(mean), respectively, whereas the deviations between DIR-based accumulations and DVH summation were small and well within 1 Gy. For the investigated treatment scenario, DIR-based bladder dose accumulation did not result in substantial improvement of dose estimation as compared to the straightforward DVH summation. Large variations were found in individual patients between the doses from the initial treatment plan and the accumulated bladder doses. Hence, the use of repeat imaging has a potential for improved accuracy in treatment dose reporting.

Rehabilitation after stroke: predictive power of Barthel Index versus a cognitive and a motor index.

The aim of the present study was to investigate the predictive power of ratings of Barthel Index at Day 40 post stroke, compared with and/or combined with simultaneous ratings from a mobility scale (EG motor index) and a rather simple cognitive test scale (CT50). The parameter to be individually predicted was the need for special living facilities and support at discharge from a rehabilitation hospital, as well as six months later; 53 stroke patients with age median 68 years were included in this prospective study. It was shown that a combination of Barthel Index and CT50 had a stronger predictive power than Barthel Index alone. A combination of EG motor index and CT50 had at least the same predictive power as the combination of Barthel Index and CT50. The usefulness of a simple diagram for individual prognostication was demonstrated.

Feasibility of detecting hypoxia in experimental mouse tumours with 18F-fluorinated tracers and positron emission tomography--a study evaluating [18F]Fluoro-2-deoxy-D-glucose.

The study was designed to investigate the binding of [18F]Fluoromisonidazole ([18F]FMISO) and [18F]Fluoro-2-deoxy-D-glucose ([18F]FDG) in a C3H mouse mammary carcinoma. Non-anaesthetized tumour-bearing animals breathing either normal air or carbogen (to reduce tumour hypoxia) were examined by PET after tracer injection. Tumours were identified by radioactive labelling and methods of defining regions of interest (ROI) in the tumours were investigated. Reference tissue was selected elsewhere in the mice and the ratio between mean radioactivity in tumour and reference tissue was compared. The results showed a correlation between the methods of identifying ROIs and a significantly lower tumour to reference tissue ratio for carbogen-treated mice compared with controls when using [18F]FMISO. Only one of the methods showed a significant difference in the tumour labelling between treatment groups using [18F]FDG. The study supports the contention that [18F]FMISO may be able to identify hypoxia in tumours, whereas a similar role for [18F]FDG is more doubtful.

Non-invasive tumour blood perfusion measurement by 2H magnetic resonance.

Deuterium uptake into foot-implanted C3H murine mammary carcinomas was measured non-invasively by 2H NMR spectroscopy at 46 MHz after i.v. injection. The arterial input function (AIF) was estimated from 2H NMR measurements with a second radiofrequency coil externally located over the heart. Tumour and heart data were acquired over the same time period by means of a switch automatically activated every 1.6-3.2 s. Although the AIF data were, in general, partly contaminated by signals from adjacent tissue, a mathematical fitting procedure involving simultaneous fitting of the AIF and the tumour kinetics gave robust results for tumour blood perfusion (TBP): up to four repeat TBP measurements were made in 14 out of 20 untreated animals and TBP could be measured before and after treatment in 14 out of 15 animals. The ability of this technique to measure changes in blood perfusion was assessed using hydralazine, which decreased TBP from 91 to 29 ml 100 g(-1) min(-1) and this was comparable to a 70% reduction in relative TBP measured by laser Doppler flowmetry.

Clinical trial of intensive muscle training for chronic low back pain.

105 patients who had chronic low back pain without clinical signs of lumbar nerve root compression or radiological evidence of spondylolysis or osteomalacia were randomised to three treatments: 30 sessions of intensive dynamic back extensor exercises over three months; a similar programme at one-fifth the exercise intensity; or one month of thermotherapy, massage, and mild exercises. The results consistently favoured intensive exercise, which had no adverse effects. Since these exercises can be conducted in groups, the intensive programme is no more costly than conventional strategies that require individual attention.

Clinical examination of pelvic insufficiency during pregnancy. An evaluation of the interobserver variation, the relation between clinical signs and pain and the relation between clinical signs and physical disability.

The purpose of this study was to answer the following questions: Do clinical signs in pregnant women with pelvic pain differ from signs in those without pelvic pain? Is there variation between the test signs found by four observers? Are the clinical signs correlated to pain and physical disability? Twenty pregnant women with pelvic pain and 20 pregnant women without pelvic pain were participating. Each woman reported her own pain sensation and physical disability and each woman was examined by 4 physiotherapists independently. Sixty-one clinical tests were applied. Only 8 tests showed predominantly positive signs in the pain group. These tests showed agreement between different observers judged by a kappa coefficient > 0.40. The number of positive clinical signs was well correlated to the reported pain and physical disability. The value of an extensive examination of posture, muscles and joints on pregnant women with pelvic pain is dubious.

Resistive breathing training in severe chronic obstructive pulmonary disease. A pilot study.

We studied the effects of resistive breathing in 10 patients with long-standing, severe disabling COPD. Small increases in inspiratory resistive load resulted in diaphragmatic fatigue and failure in all patients. Fatigue was detected using the frequency spectrum analysis of an EMG signal obtained with surface electrodes. Failure was defined as an inward displacement of the abdomen during inspiration, i.e. incoordination of thoracoabdominal motion. The patients trained for one half hour daily for 4 weeks, breathing into a simple device, where they inspired against a resistive load that produced some incoordinated breaths. After 4 weeks this load was increased, if possible, and another 4-week training period started. All patients improved with training, i.e. higher resistances could be tolerated without signs of fatigue and failure. In addition most patients claimed that training had helped them in their daily living; they were able to do more without getting short of breath. The device helped expectoration, possibly owing to the effect of the small expiratory resistance.