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P Aletti

Publications and source records attributed to P Aletti.

At least 19 recordsLinked to original sources
PubMed2004

[Intensity-modulated radiation therapy for head and neck cancers with bilateral irradiation of the neck : preliminary results].

PURPOSE: To report preliminary results of a prospective study of intensity-modulated radiotherapy (IMRT) for head and neck squamous cell carcinoma (HNC) with bilateral irradiation of the neck. PATIENTS AND METHODS: At the Alexis Vautrin Cancer Center, 23 patients have been treated with IMRT for HNC since January 2002-August 2003. The first 10 patients with a minimum follow-up of 3 months were analyzed. All tumors were oropharyngeal. There were four females and six males, with a mean age of 50 years (range 39-66). Stages were I-II in eight and III-IV in two. CTV1 was microscopic disease and N0 neck (prescribed dose : 50 Gy) and CTV2 was macroscopic disease and the volume at risk (prescribed dose: 66-70 Gy). PTV were CTV + 5 mm. Patient's immobilization consisted of a five-point head neck shoulder thermoplastic mask. Set-up verifications were done by semi-automatically matching portal images and digitized reconstructed radiographs. IMRT used dynamic multileaf collimation. Five patients (group A) received 50 Gy IMRT (two post-operative and three with a brachytherapy boost with a mean dose: 27.5 Gy), and five patients (group B) received 66-70 Gy IMRT (four post-operative). Acute and late normal tissue effects were graded according to the RTOG-EORTC radiation morbidity scoring criteria. RESULTS: With a median follow-up of 7.4 months (range 3-18.5), no patient died or had loco-regional relapse. The displacements were <4 mm in 98% cases. CTV1 and 2 received 95% of the prescribed dose in 100% of the volume. On average the mean dose to the contralateral parotid was 25.5 Gy for group A vs. 31 Gy for group B (P = 0.09). Mean doses <26 Gy were obtained in three of five patients in group A vs. zero of five patients in group B (P = 0.04). Acute skin toxicities were grade 1 in five patients, grade 2 in four and grade 3 in one. Acute mucositis cases were grade 1 in three patients, grade 2 in five and localized grade 3 in two. At 3 months, 50% of the patients had a grade 0-1 late xerostomia. CONCLUSION: The 26 Gy dose limit constraint to the contralateral parotid was easier to satisfy when IMRT was prescribed at a maximum dose of 50 Gy. Acute toxicity is low. The displacements in the mask indicate that it is possible to define the PTV as CTV + 4 mm. This reduction should decrease the mean dose to the parotids. At 3 months, a 50% rate of grade 0-1 late xerostomia encourages the hope of a very low rate at 2 years.

Adult↗
PubMed2003

[Quality assurance program for intensity-modulated radiotherapy (IMRT) treatments of head and neck carcinomas].

A new technique such as intensity-modulated radiotherapy needs a quality assurance program. A French cooperative group joined to define a common program for the use of this technique in the case of head and neck carcinomas. Specific controls are necessary and even mandatory, for example: leaves position, speed of the leaves and the linearity of the dose with the monitor unit number. Measurements in homogeneous phantoms will validate calculated treatment plans. Absolute and relative measurements need ionisation chambers and films. Measurements for each beam, gantry at 0 degrees, are basic measurements. If those are impossible due to the treatment planning software, they can be performed with the treatment angles, films of course positioned perpendicularly to the beam axis. A consensus must be established between members to reduce the frequency and the number of measurements. Nevertheless, it currently seems mandatory to maintain measurements for each beam. Moreover, incidents that happen during this kind of treatment have to be recorded and new verifications will have to be realised then. This program is a unique possibility to match the application of a new technique whatever the type of equipment.

Algorithms↗
PubMed2003

[High dose rate brachytherapy: a potentially curative treatment for small invasive T1N0 endobronchial carcinoma and carcinoma in situ].

INTRODUCTION: High dose rate brachytherapy (HDR-BT) is an option for treatment of small invasive endobronchial carcinoma and carcinoma in situ. This retrospective study describes the results of 33 consecutive patients treated with curative intent and followed up for more than one year. METHODS: Between July 1994 and October 1999, 35 tumours were treated with HDR-BT alone using a standard protocol delivering 6 fractions of 5 Gy delivered across 1cm from the catheters over 3 to 6 weeks. In 31 patients, surgical treatment was ruled out because of histology (in situ carcinoma), history of pneumonectomy or significant co-morbidity. Two patients were treated for positive resection margins following pneumonectomy. All the tumours were Tis or T1 N0. RESULTS: The locations of tumours were: trachea - 2, main bronchus - 5, lobar - 20, and segmental - 8. Only one catheter was needed in 15 cases, 2 in 13 cases, 3 in 6 cases and 4 in 1 case. The median follow-up was 17 months (range, 5-53 months). The recurrence-free rate was 94.3% at 2 months and 86.2% at 6 months after the treatment. 15 patients (45.5%) developed local recurrence at a median time of 9 months. Three patients developed metastases. The 1-year and 2-year overall survival rate were 71.4% and 53.8% respectively and specific survival rates were 69.4% and 59%. One patient developed an acute pneumothorax, and late complications included 6 infections and 12 bronchial stenoses. There were no episodes of haemoptysis nor lethal complications. CONCLUSIONS: With strict selection criteria, HDR-BT can be a curative treatment for early invasive or in situ endobronchial carcinoma without serious toxicity. It is therefore a good alternative treatment with curative intent for inoperable patients.

Adult↗
PubMed2002

[Conformal radiotherapy in prostate cancer: for whom and how?].

External radiotherapy is one of the modalities used to cure localized prostate carcinoma. Most of localized prostate carcinomas, specially those of the intermediate prognostic group, may benefit from escalated dose above 70 Gy at least as regard biochemical and clinical relapse free survival. 3D-CRT allows a reduction of the dose received by organs at risk and an increase of prostate dose over 70 Gy. It is on the way to become a standard. Intensity modulated radiation therapy increases dose homogeneity and reduces rectal dose. These methods necessitate rigorous procedures in reproducibility, delineation of volumes, dosimetry, daily treatment. They need also technological and human means. It is clear that localized prostate cancer is a good example for evaluation of these new radiotherapy modalities.

Adenocarcinoma↗
PubMed2000

Dose escalation with 3D-CRT in prostate cancer: French study of dose escalation with conformal 3D radiotherapy in prostate cancer-preliminary results.

PURPOSE: To evaluate the feasibility of dose escalation in a multi-institutional study in prostate cancer patients. METHODS AND MATERIALS: Between October 1995 and October 1998, 164 patients with localized adenocarcinoma of the prostate were treated with 3-dimensional conformal radiotherapy at one of five French institutions. The dose of radiation was escalated from 66 to 80 Gy (ICRU point). The maximum dose to the rectal wall was limited to 75 Gy. RESULTS: Results were compared in two groups, one (group 1) receiving the standard dose (n = 46 patients; 66 to 70 Gy) and the other (group 2) receiving the escalated dose (n = 118 patients; 74 to 80 Gy). There was no difference in the characteristics of patients between the two groups. The mean follow-up time was 32 months in group 1 and 17.5 months in group 2. No statistical difference between the two groups was observed in the incidence of late gastrointestinal and urinary toxicities. The probability of achieving a posttreatment prostate-specific antigen nadir of </=1 ng/mL in the 120 patients who did not receive neoadjuvant androgen-deprivation therapy was significantly higher in the dose-escalation group and was directly related to the dose of radiation given. CONCLUSION: This multi-institutional study demonstrated the feasibility of escalating the dose of radiation to 80 Gy in prostate cancer patients.

Adenocarcinoma↗
PubMed1999

Preprocessing of control portal images for patient setup verification during the treatments in external radiotherapy.

The main problem in processing the control portal images is their poor quality. We have developed a way of improving the image quality to allow a segmentation stage. Three items were studied for this purpose the background gradient of intensity correction, the noise reduction, and the image restoration. The background was corrected by subtracting a smoothed version of the image from the original. We tested 15 noise reduction methods. The most appropriate for control portal images was found to be the truncated average. Finally, four restoration techniques were compared. The maximum a posteriori (MAP) algorithm was the most efficient. The algorithms were tested over a wide range of conditions (image quality). They produced a great improvement in anatomic detail for all the imaging systems, energies, and anatomical zones tested. For example, the signal-to-noise ratio of a SRI-100 pelvis image, acquired with 4 monitor units (MU) at 10 MV (very low quality image), increased from 0.97 to 42.84 after preprocessing. We found that the improvement in image quality facilitated or even enabled segmentation of the control portal images. The percentage of segments belonging to a structure increased from 30% to 65% in the example cited. The preprocessing of control portal images is the first step in checking the patient setup.

Algorithms↗
PubMed1999

Control portal images enhancement.

The general aim of our study is the patient setup verification using control portal images during the treatments. The main problem of the control portal images processing is their poor quality. We investigated a way of improving the image quality in order to allow a segmentation stage. Four items were studied for this purpose: the presence of distortion, the background gradient of intensity correction, the noise reduction, and the image restoration. The absence of significant distortion was checked with a grid pattern phantom. The background correction was performed by the subtraction from the original image of a smoothed version of this image. We tested 14 noise reduction methods. The most appropriate for our images is the truncated average. Four restoration techniques were compared. The Maximum a Posteriori algorithm is the most efficient. For all the imaging systems, the energies, and the anatomical zones tested an important improvement in anatomic detail was apparent. For example, the SNR of a SRI-100 pelvis image (4 monitor units at 10 MV), went up from 0.97 to 20.06 after enhancement. The image quality improvement will facilitate or enable the segmentation of the control portal images. It is the first step in the patient setup verification.

Humans↗
PubMed1998

A semi-empirical method for calculating the effect of air gap space on output factors on electron beam dose distributions.

BACKGROUND: A simple approach to calculate the effect of air gap on output factors on electron beam dose distribution is presented. METHODS: The method accounts for variations of pencil beam parameters using a model developed by Bruinvis et al. [4,5]. The evaluation of this method is based on measurements of the output factors at various distances between the final collimating device and the phantom surface. RESULTS: Comparison of calculations and measurements of output factors for various cone sizes and 0, 2 and 4 cm air gaps show agreement to within approximately 1.5% for electron energies of 6-13.5 MeV and field sizes of 5.3-10 cm in diameter. CONCLUSION: The accuracy of this semi-empirical method can be considered clinically acceptable and reduces the amount of experimental work needed.

Air↗
PubMed1997

Complications following definitive irradiation for cancers of the oral cavity and the oropharynx (in a series of 1134 patients).

PURPOSE: To study the rate and severity of complications in a series of 1134 patients treated by definitive irradiation for tumors of the oral cavity (772 cases) or the oropharynx (361 cases). METHODS AND MATERIALS: Patients were staged as 29.5% T1, 42% T2, 26% T3, 2.5% T4-Tx, and 74.5% N0 tumors. We treated 364 patients with brachytherapy only (192Ir) for the primary lesion. External irradiation and brachytherapy were combined for 770 patients. RESULTS: The results included local control and survival. Out of 1134 patients, 330 had 376 complications. Grade 1 complications occurred in 20% of the patients, Grade 2 in 9%; Grade 3 in 4%; and Grade 4 in 0.2%. Of the Grade 1 complications, 78% were soft tissue and only 24% were bone complications. For the more severe grades (2, 3, and 4), there were 56 soft tissue complications and 90 bone complications out of 1340 patients. The statistical analysis included tumor-related factors and treatment-related factors. For the first two factors, only tumor location was significant. The treatment-related factors significant for complications were studied in univariate and multivariate study. This multivariate study confirmed that for soft tissue complications dose rate and volume treated were important (p < 0.001). It also confirmed that for bone complications, total dose > 80 Gy, dose rate > 0.7 Gy/h, and the absence of leaded protection of the mandible were all important factors. CONCLUSION: This statistical study should allow future reduction of severe complications (Grades 2, 3, 4), if treatment factors inducing them can be taken into account. This is not always possible for very large tumors.

Analysis of Variance↗
PubMed1997

Conservative treatment by irradiation of epidermoid cancers of the anal canal: prognostic factors of tumoral control and complications.

UNLABELLED: We analyzed in a retrospective series of patients treated by conservative irradiation for an epidermoid cancer of the anal canal (ECAC) the prognostic factors of locoregional control (LRC), survival, late severe complications (LSC), and sphincter conservation (SC). METHODS AND MATERIALS: From 1976 until 1994, 118 patients presenting with an ECAC were conservatively treated (mean age, 65 years). According to the 1987 International Union Against Cancer (TNM) classification, they were: 19 T1, 70 T2, 22 T3, 7 T4, 94 N0, and 24 N1-3. The treatment started with external beam irradiation (EBI) (36 Gy in 3 weeks or 45 Gy in 5 weeks). Concomitant chemotherapy (5-fluorouracil and mitomycin C) was delivered to 31 patients. Two months later, a boost of 20 Gy was delivered by interstitial 192Ir brachytherapy to 101 patients and EBI in 5. Twelve other patients had an abdominoperineal resection (APR). The mean follow-up was 6 years. RESULTS: At 5 years the overall survival was 60%, and specific survival (SS) was 75%; it was 94% for T1, 79% for T2, 53% for T3, and 19% for T4. In multivariate analysis, tumor size (> or = 4 cm), node involvement, and no response to the EBI were factors of poor prognosis for SS. Thirty-two locoregional recurrences occurred of which 21 were local recurrences in the 106 patients treated by a conservative schedule. Only tumor size and response to the EBI were prognostic factors on multivariate analysis for local and LRC. A total of 17 patients presented with LSC (Grade 3, 16 patients; and Grade 4, 1 patient), which was treated by APR in 4 patients and colostomy in 11 (of which 7 were definitive). The only significant prognostic factor for LSC in the multivariate analysis was the total extrapolated response dose of irradiation. The definitive rate of SC after conservative treatment in cured patients was 100% for T1, 82% for T2, 58% for T3, and 100% for T4. Since 1989, improvements of the technique have allowed reduction of the LSC in maintaining the same local control. CONCLUSION: The results of this series are similar to those of the literature. The confirmation of pretherapeutic prognostic factors related to response to the treatment should allow us to adapt the therapeutic intensity for each case to obtain better tumor control, with as few sequelae as possible, to yield a better rate of SC.

Adult↗
PubMed1997

[Optimization of dose distribution of radiation in cancers of the cavum: association of an expert-system and a mathematical algorithm].

Optimization of radiation therapy in nasopharyngeal carcinoma is particularly complex due to both the proximity of at risk organs and the high dose that has to be delivered. To obtain an optimal dose distribution, a knowledge-based optimization technique has been designed that associates an expert-system, named CAVCAV, with numeric optimization (gradient projection method). Based on clinical and physical criteria, CAVCAV determines the geometric characteristics of the radiation fields (beam direction, location and shape of the shielding blocks) for the three stages of radiation therapy of nasopharyngeal carcinomas. Stage 2-treatment fields proposed by CAVCAV, though not perfectly adapted to the patient, are mathematically (beam weights, beam directions, isocenter position) and geometrically (adaptation of fields and shape of blocks by virtual simulation) optimized.

Algorithms↗
PubMed1996

[Recent progress in radiotherapy].

UNLABELLED: Radiation therapy has considerably evolved in 1 century. After the revolution due to cobalt in the beginning of the sixties, we are now entering the 2nd revolution in three fields in external radiotherapy. METHODOLOGY: the development of quality assurance programmes gives the guarantee that the treatment is done as it is prescribed. Technology: recent developments allow conformal radiation therapy which permits to increase the dose without increasing side effects. Biology: the implementation of predictive assays will permit to choose the best modality of treatment for each patient. In brachytherapy, the use of high dose rate radioactive sources increases indications in locations not yet accessible. Pulse dose rate brachytherapy increases radio-protection and will make optimization possible in complex volumes. In the future, indications of curative radiotherapy will probably increase in regard to earlier diagnosis of many cancers and to increase of efficacy of general treatments on metastatic disease.

Brachytherapy↗
PubMed1996

Role of interstitial brachytherapy in oral and oropharyngeal carcinoma: reflection of a series of 1344 patients treated at the time of initial presentation.

Our study focuses on a series of 1344 cases of carcinoma of the oral cavity and oropharynx treated between 1973 and 1992. Brachytherapy was always performed with iridium 192, either alone or in combination with external-beam irradiation or with surgery for the treatment of the primary tumor. For the oral cavity, we studied 565 cases of mobile tongue. The local control and overall survival rates, respectively, at 5 years are as follows: for T1, 92% and 70%; for T2, 62% and 42%; and for T3, 50% and 29%. For the subgroup T1T2NO, there was a better prognosis for treatment by brachytherapy of the primary lesion alone (p < 0.0001). Two hundred seven cases of floor-of-mouth carcinoma have been reported. The T3T4 patients were not considered surgical candidates. The local control and overall survival rates, respectively, at 5 years are as follows: for T1, 97% and 71%; for T2 72% and 42%; and for T3, 51% and 35%. Ninety-seven patients were treated by postoperative brachytherapy. These were patients for whom the margins after surgery were positive or narrow. A technique termed the modified bridge is described for lesions located in the mandible. Carcinomas of the buccal mucosa are rare in our country; only 42 cases were treated in this comparison of two techniques, and the overall survival rate was 48%. Epidermoid carcinomas of the oropharynx have nearly always been treated by a combination of external-beam irradiation and brachytherapy because of the bilateral node risk. Seventy-two patients with epidermoid cancers of the base of the tongue had an overall survival rate of 44%. The tonsil, soft palate, and pillars benefited from the use of the loop technique of brachytherapy combined with external-beam irradiation. Three hundred sixty-one patients were treated. Among these patients were two groups with different prognoses. Patients with tonsil, soft palate, and posterior pillar carcinomas had a local control rate of 84% and an overall survival rate of 57%. Conversely, the anterior pillar and the pharyngoglossal sulcus have a local control rate of only 65% and an overall survival rate of 38%. Statistical analysis revealed the prognostic factors for local control. The complications were classified into four grades: minor (20%), moderate (9%), major (4%), or inducing death (0.2%). The bone complications of grade 2 or 3 are more frequent for the floor of the mouth than for other locations.

Brachytherapy↗
PubMed1996

[Value of the combination of external radiotherapy and curietherapy in carcinoma of the velo-tonsillar region. Statistical study of a series of 361 patients].

From 1977 to 1991, we treated 361 carcinomas of the velotonsillar region, either by brachytherapy alone (18 cases), or by an association of external radiotherapy and brachytherapy (343 patients). The latter was performed using a special technique with iridium wires in plastic tubes with afterloading. The primary was the tonsil in 128 patients, the soft palate in 134 patients. We numbered also 9 posterior pillars, 63 anterior pillars and 27 velotonsillar sulcus. According to the UICC staging system (28), we classified the patients in 90 T1, 141 T2, 119 T3, 2 T4, 9 Tx with 230 N0, 93 N1, 9 N2, 20 N3 and 9 Nx. The results at 5 and 10 years show respectively: local control (LC) 80% and 75%, locoregional control 75% and 70%, global survival 53% and 28%, specific survival 63% and 52%. The univariate study shows at 5 years a better local control for T1-T2 (87%) than for T3 (67%) with p = 0.00004. The locoregional control is better for N0 (80%) than for N+ (66%) with p = 0.002, this is the same for global survival (59% versus 42%, p = 0.002). The two groups were individualised according to the primary. Inside each of these groups, the prognosis is identical for different localisations, which allows to put them together. We can therefore distinguish a group A which includes the tonsil, the soft palate and posterior pillar. This group has a better prognosis (controls and survivals) than group B (anterior pillar and velotonsillar sulcus) (p < 0.002). The tumours extended to the mobile tongue, the base of the tongue or the velotonsillar sulcus have a poorer prognosis than those without propagation or with an upwards propagation (p < 0.002). The statistical study of radiobiological factors that can influence the tissular repair shows that there are less recurrences if the duration of treatment is inferior to 55 days and if the interval between external irradiation and brachytherapy is inferior to 20 days. A sufficient safety margin seems also necessary for a good local control. The dose rate within the limits used does not seem to influence the local control and the total dose delivered to the tumour, but this is not surprising since the highest doses are given to the tumours with the smallest regression during external irradiation. The multivariate study for local control shows that the most significant factors are the T, the tumoral localisation and the total duration of treatment. For complications (classified in 4 stages), the dose rate is the most significant factor.

Adult↗
PubMed1995

Detection of errors in individual patients in radiotherapy by systematic in vivo dosimetry.

We report 5 years of systematic measurements of the dose delivered to each patient undergoing radiotherapy treatment with photon beams in order to detect any systematic error that may have escaped the different checks performed at each step of planning and calculation prior to the first treatment session, or may have arisen during the set-up or the treatment delivery. For each patient the target-absorbed dose is derived from the entrance and exit doses measured by silicon diodes, on the beam axis at the patient's skin. Depending on the discrepancies observed between the measured and expected doses we have set decision levels for the corrective actions to be taken. In addition these measurements allow us to obtain information on the overall accuracy or on the quality of a specific treatment. During 5 years, 7519 patients have been measured and 79 errors were detected. Half could have induced a variation of over 10% in the dose delivered. Seventy-eight out of 79 errors were of human origin. As part of an overall quality assurance programme, it is of the utmost importance to check the dose delivered for each patient undergoing radiotherapy treatment in order to avoid systematic underdosing or overdosing.

Absorption↗
PubMed1995

Indications, techniques and results of postoperative brachytherapy in cancer of the oral cavity.

PURPOSE/OBJECTIVE: We tried to reduce the number of local recurrences after surgery and external beam irradiation (EBI) in carcinoma of the oral cavity, when margins were positive or close. MATERIAL AND METHODS: From 1980 to 1992, we treated 97 cases of carcinomas of the oral cavity by postoperative brachytherapy. Surgery was combined with EBI+brachytherapy in 51 cases and with brachytherapy alone in 46 cases. We treated 29 T1, 34 T2, 30 T3T4 and four Tx (73% were N0 at first examination and 23% had positive nodes). The type of surgery is analysed. Brachytherapy was performed in one or two planes along the surgical scar. If the mandibular rim was resected, especially when the tongue or the remaining floor were sutured to the internal face of the inferior lip or to the buccal mucosa, the bridge technique was used. To decrease the dose to the inferior part of the mandible, the bridge was modified thanks to experimental dosimetry. RESULTS: At 5 years, the local control (LC) is 89%, the locoregional control (LRC) 82%, the specific survival (SS) 74% and the overall survival (OS) 67%. COMPLICATIONS: We noted 19% of grade 1 (minor), 12% of grade 2 (moderate) and 6% of grade 3 (major) complications. CONCLUSION: Compared with the results of the literature, we think that postoperative brachytherapy can improve classical radiosurgical results in selected cases with a risk of local recurrence.

Brachytherapy↗
PubMed1995

[Conformal radiation therapy. Fédération nationale des centres de lutte contre le cancer (FNCLCC)].

The authors present the summary of a workshop of a group of radiation oncologists and radiation physicists on three dimensional treatment planning and conformal radiation therapy with multileaf collimator. It appears that this technic must be considered as experimental and that it cannot be promoted in all radiotherapy departments without scientific and clinical evaluation.

Evaluation Studies as Topic↗