Interobserver agreement on definition of the target volume in stereotactic radiotherapy for pancreatic adenocarcinoma using different imaging modalities

PURPOSE

The aim of this study was to evaluate interobserver agreement (IOA) on target volume definition for pancreatic cancer (PACA) within the Radiosurgery and Stereotactic Radiotherapy Working Group of the German Society of Radiation Oncology (DEGRO) and to identify the influence of imaging modalities on the definition of the target volumes.

METHODS

Two cases of locally advanced PACA and one local recurrence were selected from a large SBRT database. Delineation was based on either a planning 4D CT with or without (w/wo) IV contrast, w/wo PET/CT, and w/wo diagnostic MRI. Novel compared to other studies, a combination of four metrics was used to integrate several aspects of target volume segmentation: the Dice coefficient (DSC), the Hausdorff distance (HD), the probabilistic distance (PBD), and the volumetric similarity (VS).

RESULTS

For all three GTVs, the median DSC was 0.75 (range 0.17-0.95), the median HD 15 (range 3.22-67.11) mm, the median PBD 0.33 (range 0.06-4.86), and the median VS was 0.88 (range 0.31-1). For ITVs and PTVs the results were similar. When comparing the imaging modalities for delineation, the best agreement for the GTV was achieved using PET/CT, and for the ITV and PTV using 4D PET/CT, in treatment position with abdominal compression.

CONCLUSION

Overall, there was good GTV agreement (DSC). Combined metrics appeared to allow a more valid detection of interobserver variation. For SBRT, either 4D PET/CT or 3D PET/CT in treatment position with abdominal compression leads to better agreement and should be considered as a very useful imaging modality for the definition of treatment volumes in pancreatic SBRT. Contouring does not appear to be the weakest link in the treatment planning chain of SBRT for PACA.

Advances in rectal cancer: Real-world evidence suggests limited gains in prognosis for elderly patients

BACKGROUND

Rectal cancer treatment has improved considerably due to the introduction of total meso-rectal excision, radio-chemotherapy, and high-resolution imaging. The aim of this observational cohort study was to quantify the effectiveness of these advances using high-quality data from a representative cohort of patients.

METHODS

20 281 non-metastasized cases retrieved from the Munich Cancer Registry database were divided into three time periods corresponding to before (1988-1997), partial (1998-2007), and full implementation (2008-2019) of clinical advances. Early-onset (<50 yrs.), middle-aged, elderly patient subgroups (> 70 yrs.) were compared. The overall effectiveness of evidence-based guideline adherence was also examined.

RESULTS

Median survival improved by 1.5 yrs. from the first to the last time period. Relative survival increased from 74.9% (5-yr 95%CI[73.3 - 76.6]) to 79.2% (95%CI[77.8 - 80.5]). The incidence of locoregional recurrences was reduced dramatically by more than half (5-yr 17.7% (95%CI[16.5 - 18.8]); 6.7% (95%CI[6.1 - 7.3])). Gains in 5-yr relative survival were limited to early-onset and middle-aged patients with no significant improvement seen in elderly patients (Female 68.6% [63.9 - 73.3] to 67.6% [64.0 - 71.2]; Male 71.7% [65.9 - 77.4] to 74.0% [70.8 - 77.2]).

CONCLUSIONS

Real-world evidence suggests that recent treatment advances have lead to an increase in prognosis for rectal cancer patients. However, more effort should be made to improve the implementation of new developments in elderly patients. Especially considering, that these cases represent a growing majority of diagnosed patients.

Vibration enhanced cell growth induced by surface acoustic waves as in vitro wound-healing model

We report on in vitro wound-healing and cell-growth studies under the influence of radio-frequency (rf) cell stimuli. These stimuli are supplied either by piezoactive surface acoustic waves (SAWs) or by microelectrode-generated electric fields, both at frequencies around 100 MHz. Employing live-cell imaging, we studied the time- and power-dependent healing of artificial wounds on a piezoelectric chip for different cell lines. If the cell stimulation is mediated by piezomechanical SAWs, we observe a pronounced, significant maximum of the cell-growth rate at a specific SAW amplitude, resulting in an increase of the wound-healing speed of up to 135 ± 85% as compared to an internal reference. In contrast, cells being stimulated only by electrical fields of the same magnitude as the ones exposed to SAWs exhibit no significant effect. In this study, we investigate this effect for different wavelengths, amplitude modulation of the applied electrical rf signal, and different wave modes. Furthermore, to obtain insight into the biological response to the stimulus, we also determined both the cell-proliferation rate and the cellular stress levels. While the proliferation rate is significantly increased for a wide power range, cell stress remains low and within the normal range. Our findings demonstrate that SAW-based vibrational cell stimulation bears the potential for an alternative method to conventional ultrasound treatment, overcoming some of its limitations.

Software for automated application of a reference-based method for a posteriori determination of the effective radiographic imaging geometry

OBJECTIVES

Presentation and validation of software developed for automated and accurate application of a reference-based algorithm (reference sphere method: RSM) inferring the effective imaging geometry from quantitative radiographic image analysis.

METHODS

The software uses modern pattern recognition and computer vision algorithms adapted for the particular application of automated detection of the reference sphere shadows (ellipses) with subpixel accuracy. It applies the RSM algorithm to the shadows detected, thereby providing three-dimensional Cartesian coordinates of the spheres. If the three sphere centres do not lie on one line, they uniquely determine the imaging geometry. Accuracy of the computed coordinates is investigated in a set of 28 charge-coupled device (CCD)-based radiographs of two human mandible segments produced on an optical bench. Each specimen contained three reference spheres (two different radii r1=1.5 mm, r2=2.5 mm). True sphere coordinates were assessed with a manually operated calliper. Software accuracy was investigated for a weighted and unweighted algebraic ellipse-fitting algorithm.

RESULTS

The critical depth- (z-) coordinates revealed mean absolute errors ranging between 1.1+/-0.7 mm (unweighted version; r=2.5 mm) and 1.4+/-1.4 mm (weighted version, r=2.5 mm), corresponding to mean relative errors between 5% and 6%. Outliers resulted from complete circular dense structure superimposition and one obviously deformed reference sphere.

CONCLUSIONS

The software provides information fundamentally important for the image formation and geometric image registration, which is a crucial step for three-dimensional reconstruction from > or =2 two-dimensional views.

Psychotropic drug use, falls and hip fracture in the elderly

The use of benzodiazepines (BZD) or other psychotropic agents is an established risk factor for falls and hip fractures. The evidence supporting this association has been based solely on history and/or prescription data. In a case-control study we monitored the intake of BZD, tricyclic antidepressants (TCA) and barbiturates in patients with hip fracture by serum analysis, and compared this measurement with drug history and prescription records. The serum was BZD positive in 41% of 82 community-dwelling patients; an equivalent by history and/or prescription records, however, was detected in only 18% (p < 0.0001). In contrast, in 82 age- and gender-matched community-dwelling control patients, there was only a minor discrepancy (3%) in BZD use between anamnestic (N = 19) and analytical (N = 21) data. In 23 patients admitted from nursing homes, a similar trend was visible (39% serum positive for BZD vs 26% by drug history). Barbiturate use (N = 2) could be neglected, and TCA intake was minor (N = 7); in each case both assessments were in accordance. In conclusion, in patients with hip fracture, BZD use is substantially more frequent than reported and previously assumed, pointing to an underestimated risk factor for this injury.

[Chorea-like motor restlessness in clozapine]

Clozapine is an antipsychotic drug that has a very low incidence of extrapyramidal side effects. Only few dyskinetic and dystonic motoric alterations are described. This brief review describes three patients who developed chorea-like symptoms during a Clozapine therapy. The possible causal mechanisms of these side effect are suggested.

[Group psychotherapy for Turkish patients with a translator--a report with comments of the first, constituting session]

The needs of insufficiently treated Turkish patients motivated to offer a group-psychotherapy in cooperation with an interpreter. Only on a trickful way his expenses could be paid by the health insurance. While the plan for such a group was made, it was estimated just as a second-rate escape for such patients. But already during the course of the first group-session a therapeutic concept developed which overcame barriers of language and culture. So this experiment turned out to be an important step for developing suitable therapeutic structures for migrants.

[Existential analytic psychotherapy of conversion neurosis in migrant workers]

After a brief introduction into some existential-analytic points of view of the body and of conversion syndrome the actual socio-cultural situation of the migrant workers is explained with many details. For the understanding of the meaning of the conversion symptoms it is necessary to search for the existential concept of the patient which is actually in danger. The therapeutic procedure following this concept is demonstrated on the base of four clinical cases.

[Effect of the hodja (magic healer) on Turkish psychiatric patients in West Germany--an evaluation of clinical examples]

Turkish magic healers called hodjas are working in West-Germany today. Our knowledge about their influence on Turkish patients is poor. They are consulted at least from patients with psychogenous diseases. The degree and the multiple dimensions of their influence and the possibility for the doctor to master the conflicting cultural identity of these patients is demonstrated on the base of four clinical case-histories.

[A method for determining the hemodynamic behavior of the liver in vitro]

Hemodynamic parameters of livers--especially resistance of the sinusoids and of functional portosystemic shunts--are investigated using an electro-physical model. During liver perfusion the inflow conduit is compressed irregularly. The dynamic changes of pressure and flow allow a calculation of the volume passing the sinusoids and the functional shunts.