A new method for the placement of brachytherapy probes in paranasal sinus and nasopharynx neoplasms: regarding Kremer et al. IJROBP 43:995-1000; 1999.
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Brachytherapy↗
Biomedical subjects
P Lukas
Publications and source records attributed to P Lukas.
[Development and application of dynamic MR imaging in the evaluation of perfusion changes in rectal carcinoma during radiotherapy in clinical routine. Preliminary results].
PURPOSE: This study was aimed at measuring microcirculatory parameters and contrast medium accumulation within the rectal carcinoma during fractionated radiotherapy in the clinical setting. MATERIAL AND METHODS: Perfusion data were observed in patients with rectal carcinoma (n = 8) who underwent a pre-operative combined chemo/radiotherapy. To acquire perfusion data, an ultrafast T1 mapping sequence was carried out on a 1.5-Tesla whole body imager to obtain T1 maps at intervals of 14 or 120 seconds. The overall measurement time was 40 minutes. The transaxial slice thickness (5 mm) was chosen in such a way that both arterial vessels and the tumor could be clearly identified. The gadolinium-DTPA (Gd-DTPA) concentration time curve was evaluated for arterial blood and tumor after intravenous constant rate infusion. The method allows a spatial resolution of 2 x 2 x 5 mm and a temporal resolution of 14 seconds. Patients underwent MR imaging before and at constant intervals during fractionated radiotherapy. RESULTS: Spatial and temporal resolution of dynamic T1 mapping was sufficient to reveal varying CM accumulation levels within the tumor and to identify the great arteries in the pelvis. In 6 patients Gd-DTPA concentration-time-curves were evaluated within the tumor during radiation. Pi index of Gd-DTPA versus radiation dose showed a significant increase in the first or second week of treatment, then either returned slowly to pretreatment level or a renewed increase was observed. The average Pi-value at the beginning was 0.16 (+/- 0.049), reaching highest level of 0.23 (+/- 0.058). In all groups the rise from the Pi-value to the Pi-maximum was statistically significant. The relative increase in perfusion ranged between 20 to 83%. CONCLUSION: The results show, that the ultrafast MR-technique described above provide a suitable tool for monitoring tumor microcirculation during therapeutic interventions and offers the potential for an individualized optimization of therapeutic procedures.
Aged↗
Detection and quantitation of genetically marked acute myeloid leukemia by competitive polymerase chain reaction after autologous bone marrow transplantation: a preclinical model for minimal residual disease.
Preclinical models and methods aimed at detecting and quantitating minimal residual disease (MRD) after autologous bone marrow transplantation (BMT) for acute myeloid leukemia (AML) could facilitate assessment of innovative therapeutic strategies for their antileukemic potential. Among the various techniques exploited to identify MRD, polymerase chain reaction (PCR) proved to be a valuable tool in instances in which clonogeneic markers are involved during the evolution of disease. In human AML, however, detection of MRD by PCR is limited to a minority of subgroups, as clonospecific markers are absent or presently unknown. Although gene labeling has proved to be efficient in detecting marker-devoid leukemia cells in preclinical models, detection and quantitation by PCR have not yet been considered. We therefore developed an experimental model in which detection and quantitation of genetically marked murine AML cells are based on a highly sensitive two-step nested PCR and competitive PCR protocol, respectively. We further demonstrated its applicability to a murine syngeneic BMT model that was designed to monitor minimal numbers of gene-tagged AML cells at various time intervals after transplantation. Our results showed that detection and quantitation could reproducibly be achieved at levels as low as one in 10(6) and 10(5) cells, respectively.
Acute Disease↗
A new vacuum device for extremity immobilization.
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Artifacts↗
Repositioning accuracy: comparison of a noninvasive head holder with thermoplastic mask for fractionated radiotherapy and a case report.
PURPOSE: To compare accuracy, clinical feasibility, and subjective patient impression between a noninvasive head holder (Vogele Bale Hohner [VBH]; Wellhoefer Dosimetry, Schwarzenbruck, Germany) developed at the University of Innsbruck and the thermoplastic mask fixation system for use in fractionated external radiotherapy. We present a case report of an actual patient fixated in the VBH head holder during radiation therapy. MATERIALS AND METHODS: The VBH head holder consists of an individualized vacuum dental cast connected to a head plate via two hydraulic arms allowing noninvasive, reproducible head fixation of even uncooperative patients. Accuracy was tested and compared with that of the thermoplastic mask using the Phillips EasyGuide navigation system on five volunteers. Specific external registration points served as landmarks and their positions were compared after each repositioning. System and operator inaccuracy were also taken into account. The times taken for production and repositioning of the respective fixation devices were compared, and subjective impressions were noted. RESULTS: Mean VBH head holder repositioning accuracy was 1.02 mm while that of the thermoplastic mask was 3.05 mm. 69% of mask repositionings showed a deviation > 2 mm and 41% > 3 mm (as opposed to 8% and 1% respectively for the VBH head holder) Those points located farthest away from the respective plane of fixation showed the largest deviations. Both production and repositioning times were similar between the systems; depending upon the patient, the VBH head holder was generally better tolerated than the mask system. CONCLUSION: Due to its significantly better repositioning accuracy compared to that of the thermoplastic mask, the VBH head holder is especially suited for external radiation requiring precise repositioning due to critical tissues in immediate surrounding of the area to be irradiated.
Adult↗
[Standard versus individually planned irradiation field in radiotherapy of infradiaphragmatic lymph node sites].
PURPOSE: In prophylactic irradiation of infradiaphragmatic lymphatic nodes, the width of the paraaortic and pelvic field is given by a line joining the tips of the transverse processes of the 11th thoracic to the 4th lumbar vertebra from where the field boundary follows a straight line to the most lateral point of the acetabulum as seen in simulation film. Another way to build the field border is to project the lateral contours of the large abdominal vessels from T1-weighted coronal MR images of the abdomen on the simulator radiographs and add a 2-cm margin along the vessels delineated. In our study, we compared both methods as to full enclosure of paraaortic and pelvic lymphatics or nodal miss. MATERIAL AND METHODS: Abdominal CT scans of 81 patients with involvement of paraaortic lymph node regions were examined with maximum lymph node sizes of 2.5 cm. The distance from the center of the appropriate vertebra to the lateral lymph node contour referring to the transverse process as well as to the outside contour of the aorta on the left and the vena cava on the right side, respectively, the iliac vessels were measured from T12 through S1. At the level of the hip joint the measurement point was given by the caput femoris. RESULTS: Our measurement prove that 10% of the lymph nodes were found lateral from the transverse processes of the thoracic and lumbar vertebras and 12% outside the 2-cm safety margin from the lateral contour of the large abdominal vessels. CONCLUSION: Our data show, that the customary fields for infradiaphragmatic lymphatic nodes have so far not been able to enclose all retroperitoneal and pelvic lymph nodes with certainty.
Abdominal Neoplasms↗
[Noninvasive head fixation for external irradiation of tumors of the head-neck area].
PURPOSE: To fully utilize the technical capabilities of radiation diagnostics and planning, a precise and reproducible method of head fixation is a prerequisite. METHOD: We have adapted the Vogele-Bale-Hohner (VBH) head holder (Wellhöfer Dosimetrie, Schwarzenbruck, Germany), originally designed for frameless stereotactic operations, to the requirements of external beam radiotherapy. A precise and reproducible head fixation is attained by an individualized vacuum upper-dental cast which is connected over 2 hydraulic arms to an adjustable head- and rigid base-plate. Radiation field and patient alignment lasers are marked on a relocatable clear PVC localization box. RESULTS: The possibility of craniocaudal adjustment of the head plate on the base plate allows the system to adapt to the actual position of the patient on the radiotherapy couch granting tensionless repositioning. The VBH head holder has proven itself to be a precise yet practicable method of head fixation. Duration of mouthpiece production and daily repositioning is comparable to that of the thermoplastic mask. CONCLUSION: The new head holder is in routine use at our hospital and quite suitable for external beam radiation of patients with tumors of the head and neck.
Equipment Design↗
[3D navigation for interstitial stereotaxic brachytherapy].
AIM: The aim of this paper is to describe the adaption of 3D-navigation for interstitial brachytherapy. The new method leads to prospective and therefore improved planning of the therapy (position of the needle and dose distribution) and to the possibility of a virtual simulation (control if vessels or nerves are on the pathway of the needle). MATERIAL AND METHODS: The EasyGuide Neuro navigation system (Philips) was adapted in the way, that needles for interstitial brachytherapy were made connectable to the pointer and correctly displayed on the screen. To determine the positioning accuracy, several attempts were performed to hit defined targets on phantoms. Two methods were used: "free navigation", where the needle was under control of the navigation system, and the "guided navigation" where an aligned template was used additionally to lead the needle to the target. In addition a mask system was tested, whether it met the requirements of stable and reproducible positioning. The potential of applying this method in clinical practice was tested with an anatomical specimen. RESULTS: About 91% of all attempts lied within 5 mm. There were even better results on the more rigid table (94% < 4 mm). No difference could be seen between both application methods ("free navigation" and "navigation with template"), they showed the same accuracy. CONCLUSIONS: The accuracy of the phantom experiments and the confirmation by the experiment with the anatomical specimen showed that excellent results can be expected in clinical practice using rigid tables and patient supporting systems.
Brachytherapy↗
[Subjective psychological stress and need for psychosocial support in cancer patients during radiotherapy treatment].
PURPOSE: Psychosocial distress and patient attitude towards psychosocial support as well as the correlations with clinical and sociodemographic characteristics should be assessed. METHODS: The stress due to cancer was measured in a consecutive sample of tumor patients at the start of radiotherapy (n = 117) by use of the Hornheide Questionnaire. In addition, the interest of these patients in professional psychosocial support was assessed with the help of the Questionnaire for Psychosocial Support. RESULTS: Patients in the course of radiotherapy and patients with a poor prognosis and advanced disease were more strongly distressed. 32.7% of patients wished professional psychosocial support from the oncologist treating them, 40.6% of the patients wished support from the oncologist and additionally from a psychotherapist or social worker. Interest in professional psychosocial support correlated with the amount of distress, but not with sociodemographic variables. CONCLUSIONS: Results stress the importance of training programs for oncologists in order to improve their ability to detect psychosocial distress in cancer patients and to offer adequate emotional support to them.
Adult↗
[First experiences with computer-assisted frameless stereotactic interstitial brachytherapy (CASIB)].
PURPOSE: To reach an optimal treatment result and to avoid damage to critical structures a homogeneous dose distribution in the tumor volume with a rapid decreasing dose to the surrounding structures is necessary. Fractionated interstitial brachytherapy of tumors in the ENT region employing needles depends on exact localization of the target volume during all fractions. Therefore reproducibility of positioning of the needle(s) plays an important role. MATERIAL AND METHODS: We used the ISG Viewing Wand system in combination with the Vogele-Bale-Hohner (VBH) head holder and a new targeting device. Point of entrance, pathway, and target point of the needle were planned and insertion of the needle simulated in advance. To date we have treated 7 patients with inoperable tumors in the ENT region. The actual position of the needle in the control CT was compared to the planned position. RESULTS: The accuracy of positioning of the needle depended on the location of the tumor. In a patient with a recurrent retroorbital adenocarcinoma the mean accuracy was 1 mm. Due to soft tissue displacement in the neck region and the resulting necessity to readjust the targeting device the needle was placed with a mean deviation of 15 mm between the planned and the actual position. CONCLUSIONS: Computer-assisted frameless stereotactic interstitial brachytherapy allows for precise, reproducible and preplanned insertion of hollow needles into target structures closely adherent to the surrounding tissue, thus avoiding damage of neighbouring structures. This technique is of great advantage in treating deeply seated tumors which are fixed to bony structures, especially at the skull base. Inaccuracy in the neck region caused by soft tissue shift requires improvement of the immobilization in this region.
Brachytherapy↗
[A randomized trial of concurrent chemoradiotherapy versus radiotherapy in advanced carcinoma of the uterine cervix].
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Carcinoma↗
Expression of Apo-1/Fas (CD95), Bcl-2, Bax and Bcl-x in myeloma cell lines: relationship between responsiveness to anti-Fas mab and p53 functional status.
The down-regulation of apoptosis may be an essential mechanism for tumour cell expansion in slowly proliferating tumours such as multiple myeloma. We studied eight myeloma cell lines for the presence of Bcl-2, which inhibits apoptosis, of Bax, which counteracts Bcl-2, of Bcl-x(L) and Bcl-x(S), which act in an anti- and pro-apoptotic fashion, respectively, and of Apo-1/Fas, which induces programmed cell death, when activated by the Apo-1/Fas ligand or the relevant monoclonal antibody (mab). All cell lines constitutively expressed homogenous amounts of Bcl-2, but displayed different amounts of Bax and Bcl-x proteins. The Apo-1/Fas antigen could be detected in seven out of eight myeloma lines, but expression levels varied considerably. The relative expression levels of Apo-1/Fas correlated with that of Bax, but not with that of Bcl-2 or Bcl-x subtypes. Furthermore, the effectiveness of the Apo-1/Fas mab was associated with the relative expression levels of the Apo-1/Fas and with that of the Bax antigen, but not with that of the Bcl-2 and Bcl-x antigens. We further showed that wild-type p53 function is not required for Apo-1/Fas-induced apoptosis, nor is it necessary for the expression of Bax or Apo-1/Fas antigens in myeloma. In conclusion, our results suggest a p53-independent co-regulation of Apo-1/Fas and Bax, as well as a role for Bax in Apo-1/Fas-induced apoptosis in myeloma.
Apoptosis↗
[Abdominal irradiation in seminomas: improvement in its planning with MRT].
BACKGROUND: Standard therapy for early stages of seminomas is the irradiation of the para-aortal and paracaval lymphatic vessels. PATIENTS AND METHOD: Prior to radiotherapy coronal T1-weighted MRI of the abdomen was performed including imaging of target volume and critical organs. The position and course of the large abdominal vessels are projected on simulator radiographs of the abdomen. The target volume is enclosed by blocks, which are individual formed with a 2 cm margin along the vessels. RESULTS: An irregular course of the vessels in 34% of the patients resulted in modifications of the radiation field compared with standard fields. Thus more than 10% of the volume of the left kidney could be taken out of field in 25% of the patients. Simultaneously fields were enlarged on contralateral side to make sure that the paracaval lymphatic drainage was enclosed. CONCLUSIONS: MRI-assisted planning of radiotherapy allows a more individualized treatment by visualization of the big abdominal vessels guiding the para-aortal lymphatics. The target volume is surely enclosed, healthy organs are optimal spared.
Abdomen↗
[The flab method of intraoperative radiotherapy].
PURPOSE: Improvement of the relapse rate by locally increasing the tumor dose. METHODS: To increase the dose in the tumor bed a method for intraoperative radiation therapy has been developed. The radiation is applied using a high-dose-rate afterloading system. Flexible plastic flabs are used as applicators. Each flab contains tubes for the alterloading source. The size of the applicator is chosen to correspond to the size of the target volume. In the dosage system we use the dwell times at all source positions are equal. The dwell time has been precalculated to give the reference dose at the reference position which is located at the surface of the flab in the center of the target volume. RESULTS: The dose distributions around the flab have been calculated as a function of the thickness of the flab. If the source is not placed on a regular grid within the applicator due to a non ideal positioning of the tubes within the applicator, the dose distribution is not altered too much, if the positioning error is not larger than +/- 2 mm. The influence of a curvature of the flab has been evaluated and methods to decrease the dose at critical organs are discussed. CONCLUSION: The flab methods for IORT is safe and easy and has been demonstrated for more than 150 cases. This method allows the increase in tumor dose even in regions which are not easily treated by electron IORT due to the rigid electron applicators. Because of the rapid dose fall off, the flab method can only be used for flat target volumes like the tumor bed.
Humans↗
[MR tomography of the prostate].
Due to technical developments, such as gradient echo, turbo-spin echo sequences, fat saturation, surface coils, and endorectal coils, the potential of MR imaging in diseases of the prostate has improved significantly. In histologically proven cancer of the prostate MR tomography is the best imaging modality for tumor staging. For clinically relevant purposes, MRI following transrectal ultrasonography is the method of choice.
Humans↗
[The MRT of the breast with 2D-spin-echo and gradient-echo sequences in diagnostically problematic cases].
One or both breasts of 296 patients with equivocal clinical or mammographic findings were examined with MRI. T1-weighted spin-echo (SE) and gradient-echo (FFE) sequences were acquired before and after i.v. application of Gadolinium DTPA. 50 lesions with enhancement after Gd-DTPA were biopsied--26 carcinomas, 17 proliferating mastopathic tissues, 5 fibroadenomas and 1 abscess were found. Contrast enhanced MRI with 2D-SE and FFE sequences is an effective technique for evaluating suspicious breast lesions with high diagnostic accuracy.
Adult↗
[Imaging of retroperitoneal and mediastinal metastases of an adult testicular teratoma using MRT].
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Adult↗
[High-dose-rate brachytherapy of prostatic carcinoma with iridium 192].
In the therapy of localized prostatic cancer the radical prostatectomy shows good results within a five-year interval with no evidence of disease in nearly 90%. An important alternative is the radiotherapy by external beam or interstitial technique with iodine, gold or iridium. We use the high dose rate technique with Ir-192. In this technique five to seven hollow needles are placed in the prostate from perineal punctures under transrectal sonographic control. The three-dimensional brachytherapy planning is done according the actual needle position. A computer program calculates the radiation dose and distribution for each needle by adjustment of time and stops of the Ir-implants. The Ir-192 is temporary loaded twice with 9 Gy supplemented with external beam radiation (18 x 2 Gy). Since 1985 29 patients with localized tumor (T1-T3, N0, M0) have been irradiated. 21/29 had a pelvic lymphadenectomy before. In 85% of the patients were seen no side effects. Only one patient had a serious complication through a recto-vesical fistula. Out of the 21 followed-up patients 16 were in full remission, three had an androgen deprivation because of progression. A local tumor control could be demonstrated by cytology in 70% of the patients. This rational technique seems to be an alternative for patients not eligible for a radical prostatectomy.
Aged↗