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P Scalliet

Publications and source records attributed to P Scalliet.

At least 19 recordsLinked to original sources
PubMed2001

Comparison of setup accuracy of three different thermoplastic masks for the treatment of brain and head and neck tumors.

PURPOSE: Setup accuracy is an important factor influencing the definition of the planning target volume (PTV). The purpose of this study was to compare the setup accuracy of three different thermoplastic masks used for immobilization of patients with brain or head and neck tumors. MATERIALS AND METHODS: Thirty patients with brain or head and neck tumors were consecutively assigned to one of three different thermoplastic masks (Posifix): head mask with three fixation points (3 FP, ten patients), head and shoulder mask with four fixation points (4 FP, ten patients), head and shoulder mask with five fixation points (5 FP, four fixations plus an additional one on the top of head, ten patients). Once a week, during the session with a 6 MV linac (Elekta), orthogonal (antero-posterior and lateral) portal images were acquired for three fictitious isocenters placed during the simulation at the level of the head, the neck and the shoulders. Portal images and digitized simulator films were compared using the PIPS pro software, and displacements in antero-posterior (A-P), cranio-caudal (C-C) and medio-lateral (M-L) directions were calculated. From these displacements, 2D or 3D errors were also calculated. RESULTS: A total of 915 portal images were obtained, of which 98% could be analyzed. For the whole population, total displacements reached a standard deviation (SD) of 2.2 mm at the level of the head and the neck. Systematic and random displacements were in the same order of magnitude and reached a SD of 1.8 mm. Patient setup was slightly worse at the shoulder level with a total displacement of 2.8 mm (1 SD) for both the C-C and the M-L directions. There again, the systematic and the random components were in the same order of magnitude below 2.4 mm (+/-SD). For isocenters in the head and in the neck, there was no substantial difference in the setup deviation between the three masks. The setup reproducibility was found to be significantly worse (P=0.01) at the level of the shoulders with the 3 FP mask. For the 2D random error, 1 SD of 2.3 mm was observed compared to 0.8 and 1.2 mm for the 4 and 5 FP masks, respectively. Lastly, 90% of the 3D total deviations were below 4.5 mm for the head and the neck. In the shoulder region, 90% of the 2D total deviations were below 5.5 mm. CONCLUSION: Thermoplastic masks provide an accurate patient immobilization. At the shoulder level, setup variations are reduced when 4 or 5 FP masks are used. These data could be used for the assessment of margins for the PTV.

Algorithms↗
PubMed2001

Prescribing, recording, and reporting in endovascular brachytherapy. Quality assurance, equipment, personnel and education.

Endovascular brachytherapy is a new, rapidly growing field of interest in radiotherapy for the prevention of neointimal hyperplasia after angioplasty in both coronary and peripheral arteries. Many physics aspects of these treatments have already been addressed in the report of the American Association of Physicists in Medicine task group on 'Intravascular brachytherapy', but up to now there are no generally accepted recommendations for recording and reporting radiation doses and volumes. The terminology to be used by all individuals involved in such treatments (radiation oncologists, physicists, and interventionalists) is not clearly defined. The Endovascular Groupe Européen de Curiethérapie/European Society for Therapeutic Radiology and Oncology Working Group in this document presents recommendations for a common language for general use in endovascular brachytherapy. This proposal addresses general terms and concepts for target and dose specification as well as detailed recommendations for dose prescription, recording and reporting in endovascular brachytherapy for both peripheral and coronary arteries. Additionally, quality assurance and radiation safety aspects are briefly addressed, as are aspects related to equipment, personnel, and training and education related to endovascular brachytherapy.

Brachytherapy↗
PubMed2001

Proton RBE for early intestinal tolerance in mice after fractionated irradiation.

BACKGROUND AND PURPOSE: To determine the influence of the number of fractions (or the dose per fraction) on the proton relative biological effectiveness (RBE). MATERIALS AND METHODS: Intestinal crypt regeneration in mice was used as the biological endpoint. RBE was determined relative to cobalt-60 gamma rays for irradiations in one, three and ten fractions separated by a time interval of 3.5h. Proton irradiations were performed at the middle of a 7-cm Spread Out Bragg Peak (SOBP). RESULTS: Proton RBEs (and corresponding gamma dose per fraction) at the level of 20 regenerated crypts per circumference were found equal to 1.15+/-0.04 (10.0 Gy), 1.15+/-0.05 (4.8 Gy) and 1.14+/-0.07 (1.7 Gy) for irradiations in one, three and ten fractions, respectively. Alpha/beta ratios as derived from direct analysis of the 'quantal radiation response data' were found to be 7.6 Gy for gamma rays and 8.2 Gy for protons. Additional proton irradiations in ten fractions at the end of the SOBP were found to be more effective than at the middle of the SOBP by a factor of 1.14 (1.05-1.23). CONCLUSION: Proton RBE for crypt regeneration was found to be independent of fractionation up to ten fractions. One can expect that it remains unchanged for higher number of fractions as the lethalities for doses smaller than 3 Gy are exclusively due to direct lethal events. As a tendency for increased effectiveness at the end of the SOBP is reported in the majority of the studies, for clinical applications it would be advisable to allow for by arranging a sloping depth dose curve in the deeper part of the target volume. Finally, it must be noticed that most of in vitro and in vivo RBE values for protons are larger than the current clinical RBE (RBE=1.10).

Animals↗
PubMed2001

[Benign diseases in radiotherapy: a practice survey in Belgium. Peer review of radiotherapy in Belgium].

In 1996 and 2000, a survey of radiation practice in Belgium was performed by sending a questionnaire to the different centers asking their opinion and number of patients treated. There was a great similarity between the two surveys both for indications and total number of patients irradiated. For the most common indications (prevention of cheloids, heterotopic bone formation, hyperthyroidy ophthalmopathy), there was a trend to use similar radiation technique following recent publications. In contrast, if the number of cases of macular degeneration is declining, the prevention of vessels restenosis is becoming more and more an indication.

Belgium↗
PubMed2001

Dosimetric study of the new Intersource125 iodine seed.

The use of low energy photon emitters for brachytherapy applications, as in the treatment of the prostate or of eye tumors, has significantly increased these last few years. New seed models for 125I have been recently introduced. The aim of this study is to determine the dosimetric parameters as recommended by the AAPM in the TG43 formalism for a new iodine seed design: the InterSource125 (Furnished by IBt, Seneffe, Belgium). Measurements are made with LiF thermoluminescent dosimeters (size of 1 mm3) in solid water phantoms to obtain the dose constant, the radial dose function, and the anisotropy function. The TLDs were calibrated at 6 MV and an energy correction factor of 1.41 has been applied. The same dose parameters are also obtained by Monte Carlo calculations (MCNP4B) in solid water and in liquid water. The radial function was measured at 1, 1.5, 2, 3, 4, 5, 6, and 7 cm and calculated between 0.3 and 7 cm. The anisotropy functions were measured at 2, 3, and 5 cm and calculated between 0.3 and 7 cm. The calculated and the measured TG43 functions for solid water are in excellent agreement. We have then calculated these functions in liquid water to obtain the dosimetric information for clinical applications as per TG43 recommendations. In WTI, the calculated dose rate constant is 0.98+/-1% and the measured value is 1.03 +/- 7 %. The calculated value for water is 1.02+/- 1 %. In conclusion, the dosimetric functions for the new iodine seed InterSource125 have been determined. They are quite different from the data of the well-known model 6711 from Amersham due to the absence of silver in the new seed. The characteristics are very similar to those of model 6702.

Anisotropy↗
PubMed2000

Proton relative biological effectiveness (RBE) for survival in mice after thoracic irradiation with fractionated doses.

PURPOSE: This study aims at providing relative biological effectiveness (RBE) data under reference conditions accounting for the determination of the "clinical RBE" of protons. METHODS AND MATERIALS: RBE (ref. (60)Co gamma-rays) of the 200 MeV clinical proton beam produced at the National Accelerator Centre (South Africa) was determined for lung tolerance assessed by survival after selective irradiation of the thorax in mice. Irradiations were performed in 1, 3, or 10 fractions separated by 12 h. Proton irradiations were performed at the middle of a 7-cm spread out Bragg peak (SOBP). Control gamma irradiations were randomized with proton irradiations and performed simultaneously. A total of 1008 mice was used, of which 96 were assessed for histopathology. RESULTS: RBEs derived from LD50 ratios were found not to vary significantly with fractionation (corresponding dose range, approximately 2-20 Gy). They, however, tend to increase with time and reach (mean of the RBEs for 1, 3 and 10 fractions) 1.00, 1.08, 1.14, and 1.25 for LD50 at 180, 210, 240, and 270 days, respectively (confidence interval approximately 20%). alpha/beta ratios for protons and gamma are very similar and average 2.3 (0.6-4.8) for the different endpoints. Additional irradiations in 10 fractions at the end of the SOBP were found slightly more effective ( approximately 6%) than at the middle of the SOBP. A control experiment for intestinal crypt regeneration in mice was randomized with the lung experiment and yielded an RBE of 1.14 +/- 0.03, i.e., the same value as obtained previously, which vouches for the reliability of the experimental procedure. CONCLUSION: There is no need to raise the clinical RBE of protons in consideration of the late tolerance of healthy tissues in the extent that RBE for lung tolerance was found not to vary with fractionation nor to differ significantly from those of the majority of early- and late-responding tissues.

Animals↗
PubMed2000

[Cancer and the elderly. Management. Decision aspects].

INTRODUCTION: Age is the major risk factor for the majority of patients with cancer. More than 50% of cancers occurs after the age of 60. Cancer in the elderly is therefore a public health issue at stake. However, in daily clinical practice the elderly presenting cancer are not listened to with great interest and treatment is often not proper or suboptimal. CURRENT KNOWLEDGE AND KEY POINTS: Diagnosis in the elderly is established at a more advanced stage of cancer than in younger people; diagnostic workup is reduced and suboptimal treatments are implemented. Therefore, barriers exist that prevent the elderly from accessing the healthcare system as easily as their younger counterpart. Misconceptions about cancer also lead them to delay their first visit. As well, although treatment with curative intent and without major side-effect is feasible, physicians have misconceptions regarding therapeutic possibilities. Due to the heterogeneity of the so-called "ageing population", difficulties are related to patients' selection. FUTURE PROSPECTS AND PROJECTS: Decision in oncology for the elderly must walk a fine line in attempting to deliver the best treatment under the best conditions. Age per se must not be the only criterion for medical decision. Providing accurate information adapted to the elderly, with large circulation among healthcare professionals, should lead to the same quality of care as that in young people. Comprehensive multimodal geriatric assessments should help to further differentiate patients who may benefit from curative treatment from those for whom only palliative treatment is necessary.

Age Distribution↗
PubMed1999

Cost-minimization analysis of treatment options for T1N0 glottic squamous cell carcinoma: comparison between external radiotherapy, laser microsurgery and partial laryngectomy.

BACKGROUND AND PURPOSE: A cost minimization analysis of radiotherapy (RT), laser microsurgery (L) or partial laryngectomy (PL), which are equally effective options for T1N0 glottic SCC was carried out from the perspective of the National Health Care System. METHODS: For each modality, the various events associated with the diagnostic procedure, the primary treatment, the complications, and the salvage treatment were individualized. The charges of each of these events weighted for the frequency of occurrence were then determined using the 'fee for service' policy established by the National Health Insurance of Belgium. RESULTS: A total cost of 5172, 5847 and 11563 EURO were calculated for RT, L and PL, respectively. For L, cost included post-operative RT applied in case of positive margins (30%). For PL, the cost of the primary treatment accounted for 68% of the total cost whereas it only accounted for 50 and 43% for L and RT, respectively. For RT, L or PL, complications accounted for less than 10% of the total cost. The cost of salvage treatment reached 19, 14 and 8% of the total cost for RT, L and PL, respectively. A sensitivity analysis indicated that reduction of the duration of hospitalization decreases the costs without affecting the ranking between the three options. Also, the cost of L could be reduced even slightly below the cost of RT by decreasing the need for post-operative RT. CONCLUSIONS: RT and L have almost the same expected average cost for the treatment of T1N0 glottic SCC, whereas PL is twice as expensive.

Belgium↗
PubMed1999

The effect of 2'-2' difluorodeoxycytidine (dFdC, gemcitabine) on radiation-induced cell lethality in two human head and neck squamous carcinoma cell lines differing in intrinsic radiosensitivity.

PURPOSE: The present study investigated in vitro radio-enhancement by gemcitabine (dFdC) in two head and neck squamous cell carcinomas with different intrinsic cellular radiosensitivity. MATERIALS AND METHODS: Radiosensitive (SCC61, SF2=0.16) and radioresistant (SQD9, SF2=0.49) human head and neck squamous cell carcinomas were used. Confluent cells were incubated with dFdC and irradiated in drug-free medium with a single dose of 250 kV X-rays (0-12Gy). Cell survival curves were corrected for the toxicity of the drug alone. RESULTS: In both cell lines, radio-enhancement was observed with 5 microM dFdC incubated for 3 h prior to irradiation. Dose modification factors (DMF) at a surviving fraction level of 0.5 reached 1.3 (95% CI 1.1-1.6) and 1.5 (95% CI 1.4-1.5) for SQD9 and SCC61 cells, respectively. Radio-enhancement was associated with a modest increase in the alpha term of the linear-quadratic model. In SQD9 cells, radio-enhancement increased with dFdC incubation time. At 24h, DMF reached a value of 1.5 (95% CI 0.9-3.2). In SCC61 cells at 24h, DMF reached a value of 1.1 (95% CI 0.9-1.2). In both cell lines, radio-enhancement increased with dFdC concentration up to 5-10 microM from which values it levelled off up to 100 microM. CONCLUSIONS: The data indicated that dFdC induced a modest radio-enhancement in both cell lines. For a short incubation time, dFdC did not radio-enhance preferentially the more radio-resistant cells, whereas the opposite was observed for a longer time. In both cell lines, radio-enhancement was saturated above a dFdC concentration of 5-10 microM.

Carcinoma, Squamous Cell↗
PubMed1999

Bone marrow content measured in radioimmune bone marrow scintigraphy: intra- and inter-observer variability.

The aim of this study was to assess the possible quantification of vertebral residual bone marrow content relative to the bone marrow content of a non-irradiated vertebra. This method is based on the vertebral count activity, measured using radioimmune bone marrow scintigraphy. First, however, we had to evaluate intra- and inter-observer variability. In three patients who underwent radioimmune bone marrow scintigraphy, two independent observers measured the count density in 51 (15 lumbar and 36 thoracic) vertebrae using a manually drawn region of interest. To evaluate intra- and inter-observer variability, we calculated the means and standard deviations of the differences between measurements. Bland-Altman plots were drawn for all vertebrae as well as for three subgroups of vertebrae (the upper thoracic spine, D1-D6; the lower thoracic spine, D7-D12; and the lumber spine, L1-L5). For all vertebrae, the mean (+/- S.D.) difference, expressed as a percentage of the overall mean, was -0.44 +/- 3.3% for observer 1 and -0.3 +/- 2.1% for observer 2 for intra-observer variability; inter-observer variability varied from 0.55 +/- 3.9% to 1.28 +/- 3.7%. On the Bland-Altman plots, the data points were evenly distributed above and below the 0-line and the linear regression equations matched the line of equality almost perfectly. This pattern was observed for all the vertebrae as well as for the subgroups of vertebrae. In conclusion, our results show that the intra- and inter-observer variabilities are not great, confirming that this technique is simple and robust and can be used for further quantification of bone marrow content in the axial skeleton.

Adult↗
PubMed1999

Effect of gemcitabine on the tolerance of the lung to single-dose irradiation in C3H mice.

In an early phase II trial combining gemcitabine (dFdC) and radiotherapy for lung carcinomas, severe pulmonary toxicity was observed. In this framework, the objective of this study was to investigate the effect of dFdC on the tolerance of the lungs of C3H mice to single-dose irradiation. The thoraxes of C3H mice were irradiated with a graded single dose of 8 MV photons; dFdC (150 mg/kg) or saline (control animals) was administered i.p. 3 or 48 h prior to irradiation. Lung tolerance was assessed by the LD50 at 7-180 days after irradiation. For irradiation alone, the LD50 reached 14.45 Gy (95% CI 13.33-15.66 Gy). With a 3-h interval between administration of dFdC and irradiation, the LD50 reached 13.29 (95% CI 12.26-14.44 Gy); the corresponding value with a 48-h interval reached 13.01 Gy (95% CI 11.92-14.20 Gy). Our data also suggested a possible effect of dFdC on radiation-induced esophageal toxicity. dFdC has a minimal effect on lung tolerance after single-dose irradiation. However, a proper phase I-II trial should be designed before any routine use of combined dFdC and radiotherapy in the thoracic region.

Animals↗
PubMed1998

Age has no impact on acute and late toxicity of curative thoracic radiotherapy.

BACKGROUND AND PURPOSE: Radiotherapy is a treatment method frequently employed in the management of thoracic tumours. Although the highest incidence of these tumours is found in elderly people, tolerance to radiotherapy is not well documented in older age groups. Many physicians are tempted to alter the radiotherapy planning in a population with a supposed lower life expectancy in order to prevent acute reactions whereas late reactions are often ignored. The current study aimed to determine the influence of age on the frequency and severity of acute and late side-effects and also whether the prognosis of tumours sufficiently differed between ages to justify different attitudes towards their management. MATERIALS AND METHODS: Data from 1208 patients receiving chest irradiation and included in arms designed with RT of six EORTC randomized trials were evaluated. Data were extracted by a computer program elaborated for each study and were merged in a single database for analysis. Patients were split into six age ranges from 50 to 70 years and over. Survival and late toxicity were calculated with the Kaplan-Meier method and comparison between age groups was performed with the logrank test. The gamma-statistic test was used to test the impact of age on acute toxicity occurrence. RESULTS: Survival adjusted for the primary location of the tumour was comparable in each age group (P = 0.82). Data regarding age and acute toxicity were available for 1208 patients who experienced 640 grade > or =1 toxicities. The difference in distribution over age was not significant for acute nausea, dyspnea, oesophagitis, weakness and WHO performance status alteration. Weight loss was significantly different with regards to age with a trend toward increased weight loss in older age groups (P = 0.002). To minimize actuarial bias, only patients surviving more than 90 days were analyzed for late effect risks. Late toxicities were examined only if they occurred before an eventual tumour failure in order to avoid confusion between effects of first and second line treatments. In such conditions, 1082 grade > or =1 late toxicities were recorded in 935 patients of 1106 available for analysis. The mean time to complication was 13 months and was similar in all age groups. Forty percent of patients were free of complication at 4 years, the logrank test showing no significant difference between age groups (P = 0.57). For grade >2 side-effects, the calculation did not show any difference between each age group (P = 0.1). A detailed analysis of late dyspnea and late weakness studied with the same method did not demonstrate any difference between age groups. Only grade >2 late oesophagitis demonstrated a significant trend to be more frequent in older patients (P = 0.01), but this difference disappeared after adjustment on study (P = 0.32). CONCLUSION: The absence of toxicity observed in the current study regardless of age reinforces the conviction that age per se is not a sufficient reason to exclude patients in good general condition with thoracic tumour from curative radiotherapy when medically indicated.

Actuarial Analysis↗
PubMed1998

Does sucralfate reduce the acute side-effects in head and neck cancer treated with radiotherapy? A double-blind randomized trial.

BACKGROUND AND PURPOSE: We evaluated sucralfate, well-known in the treatment of gastric ulcers, in relation to its possible reduction of radiation-induced acute complications in the treatment of head and neck cancers. MATERIALS AND METHODS: One hundred two patients were randomized in a double-blind placebo-controlled prospective setting. All patients were treated to a minimum dose of 55 Gy in 5 weeks. Oral intake of sucralfate was started at the beginning of radiotherapy and continued during the whole treatment at a dose of 1 g six times a day. All patients were scored according to a scoring system developed in our department. Weight was checked once a week. RESULTS: Comparing the time course of the mean scores for subjective intolerance, mucositis, dysphagia, dermatitis and nausea, no statistically significant differences between the two treatment arms (sucralfate, n = 38; placebo, n = 45) were observed. The mean weight loss in the sucralfate arm was 1.6 +/- 3.4 kg while it was 1.3 +/- 2.0 kg in the placebo arm. Apart from gastrointestinal upset, the administration of sucralfate did not cause any side-effects. CONCLUSION: This trial produced no clinical evidence indicating that the oral intake of sucralfate reduces the acute radiation-induced side-effects. Therefore, we do not recommend the prophylactic use of sucralfate in patients with head and neck cancer treated by radiotherapy.

Acute Disease↗
PubMed1998

Comparison of external radiotherapy, laser microsurgery and partial laryngectomy for the treatment of T1N0M0 glottic carcinomas: a retrospective evaluation.

PURPOSE: The aim of this study was to retrospectively compare the efficacy and functional results of three treatment options for T1N0M0 glottic carcinomas applied in a single institution. MATERIALS AND METHODS: One hundred six charts of patients with biopsy-proven T1N0M0 glottic carcinomas treated between 1979 and 1995 were reviewed. There were 81 T1a and 25 T1b tumors. Forty-one patients were treated by radiotherapy (RT) (median dose of 64 Gy), 34 patients were treated by partial laryngectomy (PL) and 31 patients were treated by laser microsurgery (L) of which 10 received postoperative RT for positive margins. In 18 patients, a perceptual voice rating on a visual scale was performed by the patients themselves, three non-speech specialists and two speech therapists. RESULTS: With a median follow-up time of 63.5 months, the 5- and 10-year loco-regional control probabilities reached 91 and 87%, respectively, without any difference between the treatment groups. After salvage laryngectomy, the 5- and 10-year loco-regional control probabilities reached 97% without any difference between the treatment groups. For the whole population, overall survival reached 78 and 62.4% at 5 and 10 years, respectively. The actuarial incidence of second primary reached 19% at 10 years. Regarding the quality of voice, overall there was a trend towards a worse satisfaction index, more hoarseness and more breathiness after PL than after L or RT. CONCLUSIONS: Our data suggested that assuming proper selection of patients, RT and L yielded similar outcomes and functional results. Local recurrence can be adequately salvaged by surgery. On the other hand, PL appeared to yield similar loco-regional control probability but with a worse quality of voice.

Actuarial Analysis↗
PubMed1998

Radiotherapy in the elderly.

Older patients with cancer are frequently victims of discriminatory treatment strategies according to parameters unrelated to the tumour itself. The general approach is influenced by the belief that good tolerance to radiotherapy might be compromised in older patients and that the course of cancer might be less aggressive in this age group. Substandard treatment is therefore often offered to older patients, although this attitude is supported neither by clinical nor by scientific evidence, but rather stems from a lack of specific knowledge of the actual cancer prognosis and the tolerance to radiotherapy in the elderly. In clinical practice advanced age may result in undertreatment, even though patients may have no other medical illness and no functional impairment. Some comorbid conditions which are more frequent in older patients may complicate the outcome of treatment. However, these impaired vital functions are not an intrinsic feature of the elderly. Overall, noncompliance in radiotherapy, related to comorbidity or technical condition, is rare. Short-term radiotherapy using a large daily fraction is often advocated in elderly patients; however, this should only be considered if a palliative treatment option has previously been selected due to the high risk of late side-effects. Acute side-effects often result in decreasing doses of radiotherapy. Data on acute tolerance of radiotherapy for different types of tumours did not demonstrate a radical difference in occurrence of toxicities. 'Reducing' radiotherapy is never a solution, unless the life expectancy of the patient is obviously so short that the tumour recurrence is unlikely to occur or at least to produce substantial morbidity before the patient has died from other causes.

Age Factors↗