Search

This study shows that cannula rigidity is a major contributor to adequate pulse generation during pulsatile bypass flow. In addition, there is a discussion of the analysis which led the authors to conclude that poor pulse generation was related to cannula, and a study of the level of hemolysis induced by the Cobe/Stockert pulsatile generator.

Personalized treatment of prostate cancer would be enhanced by an assessment of cancer stage and grade from imaging, the validation of which requires the accurate co-registration of in vivo images with a gold standard for stage and grade established by histopathology. We present a visualization tool supporting an image-guided approach enabling the acquisition of histopathology images parallel to the in vivo imaging planes, simplifying this registration. This tool decreases imaging-to-specimen landmark alignment error by 62%, and decreases the time required to mark the slicing plane on the specimen by 47%. Preliminary results from our method demonstrate the alignment of regions suspicious for cancer on T2w MRI with confirmed cancer foci on histopathology, and we calculate a sub-millimeter in-plane target registration error.

The goal of this work is to quantify the impact of image-guided conformal radiation therapy (CRT) on the dose distribution by correcting patient setup uncertainty and inter-fraction tumour motion. This was a retrospective analysis that used five randomly selected prostate cancer patients that underwent approximately 15 computed tomography (CT) scans during their radiation treatment course. The beam arrangement from the treatment plan was imported into each repeat CT study and the dose distribution was recalculated for the new beam setups. Various setup scenarios were then compared to assess the impact of image guidance on radiation treatment precision. These included (1) daily alignment to skin markers, thus representing a conventional beam setup without image guidance, (2) alignment to bony anatomy for correction of daily patient setup error, thus representing on-line portal image guidance, and (3) alignment to the ‘CTV of the day’ for correction of inter-fraction tumour motion, thus representing on-line CT or ultrasound image guidance. Treatment scenarios (1) and (3) were repeated with a reduced CTV to PTV margin, where the former represents a treatment using small margins without daily image guidance. Daily realignment of the treatment beams to the prostate showed an average increase in minimum tumour dose of 1.5 Gy, in all cases where tumour ‘geographic miss’ without image guidance was apparent. However, normal tissue sparing did not improve unless the PTV margin was reduced. Daily realignment to the tumour combined with reducing the margin size by a factor of 2 resulted in an average escalation in tumour dose of 9.0 Gy for all five static plans. However, the prescription dose could be escalated by 13.8 Gy when accounting for changes in anatomy by accumulating daily doses using nonlinear image registration techniques. These results provide quantitative information on the effectiveness of image-guided radiation treatment of prostate cancer and demonstrate that the dosimetric impact is patient dependent.

The goal of this study is to validate a deformable model using contour-driven thin-plate splines for application to radiation therapy dose mapping. Our testing includes a virtual spherical phantom as well as real computed tomography (CT) data from ten prostate cancer patients with radio-opaque markers surgically implanted into the prostate and seminal vesicles. In the spherical mathematical phantom, homologous control points generated automatically given input contour data in CT slice geometry were compared to homologous control point placement using analytical geometry as the ground truth. The dose delivered to specific voxels driven by both sets of homologous control points were compared to determine the accuracy of dose tracking via the deformable model. A 3D analytical spherically symmetric dose distribution with a dose gradient of [?]10% per mm was used for this phantom. This test showed that the uncertainty in calculating the delivered dose to a tissue element depends on slice thickness and the variation in defining homologous landmarks, where dose agreement of 3-4% in high dose gradient regions was achieved. In the patient data, radio-opaque marker positions driven by the thin-plate spline algorithm were compared to the actual marker positions as identified in the CT scans. It is demonstrated that the deformable model is accurate ([?]2.5 mm) to within the intra-observer contouring variability. This work shows that the algorithm is appropriate for describing changes in pelvic anatomy and for the dose mapping application with dose gradients characteristic of conformal and intensity modulated radiation therapy.

The goal of this research is to calculate the daily and cumulative dose distribution received by the radiotherapy patient while accounting for variable anatomy, by tracking the dose distribution delivered to tissue elements (voxels) that move within the patient. Non-linear image registration techniques (i.e., thin-plate splines) are used along with a conventional treatment planning system to combine the dose distributions computed for each 3D computed tomography (CT) study taken during treatment. For a clinical prostate case, we demonstrate that there are significant localized dose differences due to systematic voxel motion in a single fraction as well as in 15 cumulative fractions. The largest positive dose differences in rectum, bladder and seminal vesicles were 29%, 2% and 24%, respectively, after the first fraction of radiation treatment compared to the planned dose. After 15 cumulative fractions, the largest positive dose differences in rectum, bladder and seminal vesicles were 23%, 32% and 18%, respectively, compared to the planned dose. A sensitivity analysis of control point placement is also presented. This method provides an important understanding of actual delivered doses and has the potential to provide quantitative information to use as a guide for adaptive radiation treatments.

Une proportion significative de patients ne bénéficie pas de la radiothérapie de rattrapage (rr) après prostatectomie radicale (pr). Cette étude vise à évaluer et comparer la précision de la tep/tdm au 18f-fch-, 68ga-psma-11 ou l’IRM-mp pour la sélection des patients susceptibles de bénéficier de rr malgré un haut risque d’échec selon les critères cliniques.

PATIENT. —A boy, aged 17, was first seen about 3 p. m. Nov. 3, 1908. He had been thrown and dragged some distance in a collision between his wagon and a street car. EXAMINATION. —Patient had been given morphin, gr. ¼, and was resting quietly. He had no severe pain, breathing was regular; pulse was 88, regular, rhythmic, and of good volume. There were numerous skin abrasions over the lower back, left thigh and knee; none in left kidney region; some swelling was apparent just below the crest of the left ilium, which latter showed preternatural mobility, with crepitus and considerable pain on manipulation. Apparently there was a transverse fracture just below the crest. The patient was examined for other injuries but none was found. He had not voided urine so that diagnosis of injury in the urinary tract was held in abeyance. The left side of the pelvis was

From 1980–1991, 164 patients with a WHO-grade II astrocytoma received radiotherapy following surgery at UCSF. All patients had CT or MRI for diagnosis and/or treatment planning. Radiation doses were above 50 Gy in most patients, usually 54 Gy or 59.4 Gy. The 5- and 10-year overall survival rates were 79% and 67%, respectively; the median survival was 12.9 years. In the multivariate analysis, KPS, histology and duration of symptoms were significant. Age, location, surgical extent, or radiation dose were not significant. The 5-year survival rates for patients with KPS≤70 and KPS70 were 60% and 87%, respectively. The 5-year survival rates for the different histologies were 95% for (mixed) oligodendroglial, 78% for ordinary, and 57% for gemistocytic astrocytomas. The 5-year survival rates for patients with a duration of symptoms ≤2 months versus 2 months were 65% and 83%. Progression free survival rates at 2-, 5- and 10-years were 77%, 68% and 50% respectively. In predicting progression free survival, only KPS was significant. Histology was important in predicting the survival following progression, with a 5-year survival of 83% in recurrent (mixed) oligodendroglial versus 33% in recurrent ordinary astrocytoma.