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G Kantor

Publications and source records attributed to G Kantor.

At least 73 records · Page 4Linked to original sources
PubMed1989

[Radiotherapy and cerebral stereotaxis. Examples of dosimetry with 3D reconstruction].

External stereotactic radiotherapy allows to irradiate a small and carefully delimited intracranial volume according to the spatial definition of the target. To determine the distribution of the dose in the volume irradiated, we developed a dosimetric programme adapted to our particular treatment conditions (arc therapy in the frontal and oblique planes converging onto the centre of the target volume with circular beams 8 to 20 mm in diameter using 18 MV X photons). The principle of the programme is a 3D reconstruction based on ten transverse CT slices. This reconstruction, related to the stereotactic coordinates defined during stereotactic localization, visualises the outline of each oblique frontal treatment plane and the outline of the three perpendicular reference planes passing through the centre of the target volume (i.e. transverse, sagittal, coronal). The isodose distribution is then calculated in the planes defined by these reconstructions. Under treatment conditions, we use the parameters measured for each beam with their additional collimation. We present an evaluation of this software performed on a phantom consisting of a skull containing a defined target.

Humans↗
PubMed1989

[Brachytherapy of cancer of the penis. Analysis of a series of 53 cases].

From 1970 through 1984, 53 patients with squamous cell carcinoma of the penis have been treated by interstitial irradiation with iridium 192 wires; in this group 33 patients have been followed for at least ten years. There were 7 T1, 31 T2, 15 T3 and 37 N0, 7N1, 6 N2, 3 N3 (WHO classification, 1979). Forty eight patients were treated by interstitial radiotherapy alone, after previous circumcision for 35 of them, and five by an association of external and interstitial radiotherapy. Eleven patients presented a local recurrence; all but one were controlled by penile amputation. Fifteen patients developed severe complications (necrosis, urethral stenoses treated by surgery) and ten of them underwent a secondary total or partial penile amputation. Complications are strongly correlated with the irradiated area and the dose (over 65 grays). Recurrences and complications may develop very late after the treatment, beyond ten years. They required 12 partial and 10 total amputations. Interstitial radiotherapy is the first line treatment for carcinoma of the penis and it is well accepted by the patients. However, to keep a reasonable rate of complications and recurrences we limit the indications of interstitial radiotherapy to the small lesions (T1-T2) and we suggest to decrease the dose under 65 grays. To avoid some local failures we treat now the whole glans.

Actuarial Analysis↗
PubMed1988

Comparative study of shortwave heating patterns in phantoms with polyethylene and silk partitions.

Specific absorption rate (SAR) and effective depths of heating patterns induced by a shortwave, pancake diathermy applicator in fat-muscle phantom are measured. Midplane partitions of polyethylene and silk screen with and without contact chemicals are used. Thermographically obtained SAR data show nearly the same value for silk-screen partitions with and without contact chemicals and slightly lower values with polyethylene partitions, provided that the partition midplanes are tightly pressed against each other. Thermometry data indicate that for low-power exposures the major error in thermographic measurements obtained after termination of heating is due to thermal diffusion and not evaporative cooling in the opened midplane of the phantom.

Diathermy↗
PubMed1987

[Autograft of bone marrow treated by in vitro chemotherapy (Asta Z 7557) for consolidation of acute leukemia in adults in the first complete remission].

Fourteen adult patients in first complete remission of acute leukemia (A.L.) [6 with acute lymphoblastic leukemia (ALL), 8 with acute non lymphoblastic leukemia (ANLL)] were consolidated with high dose cyclophosphamide and total body irradiation followed by autologous bone marrow transplantation (ABMT) with marrow cleansed in vitro by Asta Z 7557. According to our previously described protocol showing evidence for a wide range of sensitivity from patient to patient, the marrow of each individual patient was incubated with the highest tolerable dose of Asta Z 7557. This dose, individually determined, was defined as the dose sparing between 0 and 10% of CFU-GM (CFU-GM DL95). ABMT was not followed by maintenance therapy. Hematological reconstitution was significantly faster in ALL patients when compared to ANLL patients. Out of these 14 patients: 2 relapsed on months 5 and 15 respectively after ABMT, and 2 died in complete remission on months 3 and 16 respectively, of veno-occlusive disease and encephalitis. Ten patients (70%) remain in complete remission up to a median of 15 months +, with 4 patients over 24 months +.

Acute Disease↗
PubMed1986

Autologous marrow transplantation for patients with chronic myeloid leukemia in accelerated or blastic phase: report of 14 cases.

Between June 1979 and October 1983, 14 autografts were performed in 13 patients with CML (ten blast crisis, four accelerated phase). Results were disappointing: four patients died during aplasia; seven returned to chronic phase, but three died of hemorrhage, four relapsed, and three did not reverse. The main problem was the very low rate of successful engraftment. Both the collection of bone marrow after treatment with busulfan and a particular sensitivity of CFU-GM to cryoinjury were responsible for the infusion of very low doses of CFU-GM. However, we observed some promising results: In one patient in acute blast crisis, the Ph 1 chromosome disappeared, as well as the cytogenetic marker of transformation; in another patient with acute pure cytogenetic acceleration, the abnormal clone disappeared for 27 months; a third patient was maintained in a second chronic phase for 20 months. Thus we suggest that the results of autografting in chronic myeloid leukemia would be improved by infusing the largest possible dose of stem cells collected before or long after treatment by busulfan, and freezing them following a careful program.

Adult↗
PubMed1983

The performance of a new 915-MHz direct contact applicator with reduced leakage.

The technical feasibility of commercially developing a safe and effective direct contact diathermy applicator operating at the industrial, scientific, medical (ISM) frequency of 915 MHz is demonstrated. The basic design consists of a circular waveguide which is internally loaded with two orthogonal pairs of forward ridges to obtain circular polarization and two rear ridges with a probe to excite the guide. Two prototype designs are considered: the small applicator (15 cm diameter) has one annular choke covered with a 2.5-cm thick microwave absorber, and the large applicator (25 cm diameter) has two additional concentric chokes to limit leakage radiation. The performance of the applicators was evaluated in terms of the requirements of a ORH microwave diathermy test protocol to control stray radiation and deliver a thermally effective absorbed dose rate to simulated muscle tissue of a phantom with a 1-cm or 2-cm fat layer. The net power required to deliver a thermally effective 235-W/kg specific absorption rate (SAR) to such a planar phantom was determined. For this net power, leakage levels considerably less than 5 mW/cm2 (at 5 cm from applicator-phantom boundary) were obtained for the applicators in direct contact with the phantom. If a small spacing (1 cm) between these applicators and planar phantoms is introduced, the net power required to deliver an effective SAR to a phantom and the associated leakage can become excessive. For the small applicator, the required net power for inducing an SAR of 235 W/kg in muscle tissue of a 1-cm fat layer phantom is about 330 W and the leakage is about 120 mW/cm2. For a 2-cm fat layer phantom, these values are somewhat higher. For the large applicator, using a 1-cm fat layer phantom, the values are about 200 W and about 17 mW/cm2. Again, for a 2-cm fat layer phantom, these values are somewhat higher.

Diathermy↗
PubMed1982

[Advantages of thoracic CT scanning in the treatment of mediastinal lymphomas].

In order to study the possible advantages of thoracic CT scanning in the management of mediastinal lymphomas, a retrospective analysis of 16 patients was carried out. In this group, 21 thoracic CT scans were performed. For 10 patients (and 11 CT scans) we found a discrepancy between the results of "classical" radiology and those of CT scan, the latter giving more information about the precise status of the mediastinum. In 10 cases, we had to modify our treatment, either by adding chemotherapy or changing the radiation field size.

Adolescent↗
PubMed1981

An evaluation of microwave diathermy applicators using free space electric field mapping.

An electric field mapping study is described which was designed and executed to study the performance characteristics of various prototype and currently used microwave diathermy applicators operating at 2450 MHZ. A miniature diode detector/dipole probe, developed by the Bureau of Radiological Health, was used to map the 'near' electric fields in the aperture plane of each applicator. From the field mapping results, parameters for use in the evaluation of the radiation safety of various applicators are developed. A thermographic camera was used to determine heating characteristics of the applicators in simulated biological material. The thermal effectiveness of these applicators was also investigated by determining their Specific Absorption Rate, a recently developed parameter. The superiority of a specially designed prototype applicator (in terms of uniformity and effectiveness of energy deposition, and minimal leakage radiation) compared with currently used applicators is demonstrated.

Diathermy↗
PubMed1981

Unilateral nevoid telangiectasia and chronic liver disease. Report of a case and review of the literature.

Unilateral nevoid telangiectasia was observed on the back of the left hand and wrist in a 19-year old man with chronic liver disease and portal hypertension. Moreover, abnormalities of the elastic fibers of the skin were found. Examination of the liver biopsy showed extensive portal fibrosis with many dilated blood vessels. No usual cause of juvenile cirrhosis was detected. In the comment, the authors suggest that unilateral nevoid telangiectasia and liver disease could be manifestations of a disease involving skin and liver vessels, as in hereditary hemorrhagic telangiectasia.

Adult↗
PubMedDate not supplied

[Conservative treatment of extremity soft tissue sarcomas. Functional evaluation using LENT-SOMA scales and Enneking scoring].

OBJECTIVE: The aim of this prospective study is the feasibility of late effects assessment by LENT-SOMA scales after conservative treatment of soft tissue sarcomas of the extremities and a comparison with the functional evaluation by the Enneking score. PATIENTS AND METHODS: During the systematic follow-up consultations, a series of 32 consecutive patients was evaluated in terms of late effects by LENT-SOMA scales and functional results by the Enneking score. The median time after treatment was 65 months. The treatment consisted of conservative surgery (all cases) followed by radiation therapy (29 cases), often combined with adjuvant therapy (12 concomitant radio-chemotherapy association cases out of 14). The assessment of the toxicity was retrospective for acute effects and prospective for the following late tissue damage: skin/subcutaneous tissues, muscles/soft tissues and peripheral nerves. RESULTS: According to the Enneking score, the global score for the overall series was high (24/30) despite four the scores zero for the psychological acceptance. According to LENT-SOMA scales, a low rate of severe sequellae (grade 3-4) was observed. The occurrence of high-grade sequellae and their functional consequences were not correlated with quality of exerese, dose of radiotherapy or use of concomitant chemotherapy. A complementarity was observed between certain factors of the Enneking score and some criteria of the LENT-SOMA scales, especially of muscles/soft tissues. CONCLUSION: The good quality of functional results was confirmed by the two mean scoring systems for late normal tissue damage. The routine use of LENT-SOMA seems to be more time consuming than the Enneking score (mean time of scoring: 13 versus five minutes). The LENT-SOMA scales are aimed at a detailed description of late toxicity and sequellae while the Enneking score provides a more global evaluation, including the psychological acceptance of treatment. The late effects assessment by the LENT-SOMA scales should be carried on in prospectives studies, especially in case of concomitant radio-chemotherapy.

Adult↗
PubMedDate not supplied

[Understanding the information booklet "For a better understanding of radiotherapy"].

PURPOSE: To evaluate the level of understanding and the impact of the information booklet "For a better understanding of radiotherapy" for radiotherapy patients. PATIENTS AND METHODS: A survey by questionnaire was realized during the second semester 1999 with ten centers of radiotherapy in the Aquitaine area. One hundred booklets with a questionnaire and a postage-paid envelope were sent to the oncologists of these ten radiotherapy centers. A quantitative analysis of the questionnaires received and a qualitative analysis by anthropological methods (a prior reading of the document with 13 patients and a content analysis of the questionnaires, in particular of the free texts in it) were performed. RESULTS: The response rate was 10.8% for the quantitative analysis. The different actors in radiotherapy were partly identified: the oncologist and the technicians were clearly identified by 84.3% of the patients. However, their role seemed to be less discerned. The information given in the booklet was considered clear for 57.4% of the patients; 74.2% did not require explanations of the vocabulary, whereas 14.8% wanted explanations and 13.0% did not state an opinion. In the qualitative analysis, the booklet was found to be well received and understood even if technical explanations were sometimes needed. However, words in italics or small print and pictures without captions impeded the proper reading of the booklet. Finally, the personal real-life context of the patients was more present in comments during the reading with the anthropologist and in the free texts (which represented 26.9% of the received questionnaires). CONCLUSION: This booklet was judged to be useful by the patients and thought to "answer the questions which the patient may ask". It seems important to define the right moment for its distribution (the first visit, the first sequence of treatment, for example, would be more appropriate). Lastly, certain passages, especially in the introduction, could be modified so as to improve the legibility (in particular for the elderly). In addition, the informative content, largely well understood, could be extended with a glossary, using simple technical and always clear explanations.

Humans↗
PubMedDate not supplied

[Radiotherapy for a massive hepatic hemangioma in a six-week-old infant].

We report the case of a six-week-old baby who underwent irradiation for a giant hepatic hemangioma. After medical treatment including corticosteroids and interferon, no response was observed. She progressed to respiratory failure, requiring the use of mechanical ventilation. An emergency radiation therapy of the liver was decided. We observed a rapid improvement of the child, with the recovery of autonomous breathing without mechanical ventilation and a normalization of cardiac functions. Two months later, a partial left hepatic embolization was needed due to a progression of a localized blood flow. Six months later, she finally came back home. Cardiac output was normal and hepatomegaly began to regress. One year later, ponderal status is satisfactory, and it remains a localized hepatic right lobe hypertrophy without functional consequence.

Embolization, Therapeutic↗