Comparative study of permanent interstitial prostate brachytherapy post-implant evaluation among seven Italian institutes.

BACKGROUND AND PURPOSE: The purposes of this multicentric study are (a) the evaluation of four different commercially available treatment planning systems (TPSs) and (b) to verify whether the dosimetric results are comparable, also when considering the inter-observer variabilities and the different scanning protocols used. This work is to be considered a first step to test the value of multicentric studies based on dosimetric evaluation of the quality of the implants. PATIENTS AND METHODS: Four different TPSs were used and the following tests were performed:Comparison of the parameters and mathematical algorithms used; comparison of the dose distributions generated by three different geometries of sources based on 32 dose-points on each source geometry. An octagonal geometric phantom was used to compare volume algorithms and dose-volume histogram (DVH) calculations (V150(Gy), V100(Gy), V50(Gy) and V25(Gy)). Comparison of the post-plan source distribution performed on a prostate-phantom implanted with (125)I seeds. A CT scan of the phantom was obtained at each participating center. Both the geometrical coordinates (with respect to the most caudal one), and the spread of the geometrical distribution, were calculated. The volumes included within different isodoses were also collected. Comparison of the post-plan source distribution performed on an actual patient. Post-plan V100% and D90(Gy) derived from seed distributions obtained by different operators were calculated, using the same target delineation. RESULTS: All the considered TPSs satisfied the AAPM dosimetric parameter recommendations. Point-dose examinations revealed differences smaller than 5%, except for one of the systems. Although the volume algorithm was not the same for all systems, no statistically significant difference was found in the volume measurements. The DVHs also presented differences smaller than 5%, except for one TPS. The distances between the seeds, based on the same CT images, showed a mean SD of 0.13 mm. The mean maximum difference of the position of each seed was 0.36 mm. The most significant errors were made in the cranio-caudal direction (mean maximal difference: 0.44 mm); here the size of the step between slices played an important role. The algorithm of source positioning of the different TPSs may also help explain this difference. The compiled DVHs showed differences smaller than 5%. Post-plans derived from different seed distributions showed a mild dependence upon operators. We obtained a mean value of 97.8 and 152.7 with a percentage of SD of 0.43 and 1.7, respectively, for V100% and D90(Gy). CONCLUSIONS: Three-dimensional (3D) geometric reconstructions of seed distributions are slightly dependent upon the operators and the scanning protocols have little effect on the dosimetric evaluation. Some relevant discrepancies were found between one of the TPSs and the other three if few sources were used; increasing the number of seeds those differences became less pronounced. Multicentric studies on the quality of prostate implants based on post-implant dosimetry are feasible, provided an accurate step-wise evaluation of the procedure be performed.

[The polycentric multiple arc complanar technic, or telebrachytherapy. A 4-year experience (an innovative way for the local control of solid neoplasms)]. / La tecnica complanare "policentrica ad archi multipli", ovvero la telebrachiterapia. Quattro anni di esperienza (una via innovativa per il controllo locale delle neoplasie solide).

The coplanar polycentric multiple 180 degrees single arc and narrow beams technique (PMA) allows high radiation doses to be delivered to the target, with similar dose distribution to that of brachytherapy. Since 1990, more than 100 patients have been treated: 80 had NSCLC, 12 had epidermoid head and neck (oral cavity and oropharynx) cancers, 8 brain tumors, 4 esophageal cancers and, sporadically, other patients had many other kinds of tumors, e.g., Hodgkin's and non-Hodgkin's lymphomas and sarcomas. X photons of a 12-MV Linac have always been used. NSCLC patients are assessable for local control, toxicity and survival, while the other patients only for local control and/or toxicity. As for 31 stage I-II lung cancer patients, CR has been observed in 82.8% of them and PR in 13.8%; the response was always assessed with chest radiography, CT, FBS, cytology and/or histology. The overall actuarial survival rate is 71% at 40 months, the disease-free survival rate is 75% and the local progression-free survival rate is 94%. As for 49 stage-III patients, CR has been observed in 40% of them and PR in 56%. The overall disease-free survival is 10% at 28 months (median survival: 14.37 +/- 0.6 months). The disease-free survival rate is 23%. The local progression-free survival rate is similar to the overall survival rate, which seems to prove the very high metastatic spread of this disease in advanced stages. Twelve head and neck cancer patients have been treated, 5 of them in stage II and 7 in stage IV. CR has been observed in all the patients in lower stages (100%), in 4/7 patients in stage IV (57%) and in 4/5 patients (80%) in the T4N0 subgroup. The response of brain tumors treated with the PMA technique is difficult to assess because radiographic, CT and MR images are difficult to correlate with patients clinical status. The patients in our series are still alive, with a medium follow-up of 7 months (range: 2-16 months). A longer follow-up is necessary before any other considerations on the effectiveness of this method can be made. This technique was used on the patients who were not eligible for the other techniques with high doses delivered to the tumor, because of its volume and/or shape. Four esophageal cancers were treated with palliative intent, because of absolute dysphagia, in alternative to HDR brachytherapy. All these patients have obtained symptom remission.(ABSTRACT TRUNCATED AT 400 WORDS)

[Quality assurance in diagnostic radiology using an automated system. Experience and results]. / Garanzia di qualità in radiodiagnostica con l'impiego di un sistema automatico. Esperienza e risultati.

The authors report their personal experience with the use of an integrated quality control system in the radiology department. The system we used was the RTI DIGI-X Plus, a Swedish-made product, allowing a wide range of parameters to be measured on diagnostic X-ray units for general radiography, mammography and fluoroscopy. Data can be retrieved with a minimum number of measurements. The "oRTIgo" software improves the quality assurance system and ensures document compliance with international recommendations. The equipment consists of a detector unit, a processor and a display unit. The detector consists of a rotating holder with 12 combinations of metal filters of various thickness mounted in front of two photo-diodes covered with identical X-ray intensifying gadoliniumoxysulfide screens. This unit is connected to a data acquisition system controlled by a microcomputer. Peak tube voltage and total tube filtration are derived from the ratio of detector signals. The relationship between this ratio and the measured quantity is determined by a calibration procedure. Furthermore, exposure time "mAs" value, "mAs" linearity and exposure (or kerma in air) can be measured. Digital storage can be performed and input signals displayed. A serial interface is used to communicate with a PC for QC management purposes. An error propagation model is used to determine the inaccuracy of peak tube voltage measurements. With the DIGI-X Plus system, measurements can be carried out in a shorter time and the stored data reprocessed later on. After QA testing on 20 X-ray units in the radiology department, in vivo doses were measured using a TLD Harshaw 100 on 46 randomly selected patients undergoing chest examinations. The results are reported and analyzed following the NRPB protocol and show high agreement with the recommended values.

[Brachytherapy in choroid tumors]. / Brachiterapia dei tumori coroidei.

Even though brachytherapy has been used for many years to treat choroidal tumors, it is not a widespread technique because it requires much organization and operators skills. The most common methods use 60Cobalt and 106Rutenium plaques, or custom-made plaques with 125Iodine loaded seeds. Another, less common, technique uses 192Iridium wires loaded on custom-made plaques. The technique we used to treat 4 retinoblastomas and 2 choroidal melanomas uses 192Iridium wires loaded on custom-made plaques. The applicator is made of a quick drying paste poured over a sphere the same size as the eye-ball: plastic tubes are inserted, according to preliminary dosimetric measurements, to house the Iridium wires. The applicator is positioned on the eye-ball corresponding to tumor site by surgery. The Iridium sources are inserted into the plastic tubes at the end of surgical placement: this afterloading technique guarantees maximal staff protection. 192Iridium (320 keV gamma emitter) allows the dose to be transmitted deeper than with 125Iodine (30 keV gamma-emitter) and 106Rutenium (3540 keV beta-emitter). Therefore, with Iridium, the dose delivered is lower on the eye-ball surface for the same tumor dose. On the other hand, the use of 60Cobalt (1250 keV gamma-emitter) gives the healthy surrounding tissues higher doses. To conclude, this method allows us to customize the application to every single case, to reach posterior sites, to ensure radioactive protection to staff thanks to afterloading and to obtain a good depth to surface dose ratio.

[Photon or electron irradiation of the internal breast lymph node chain. Experimental dosimetry and clinical implications]. / La irradiazione con fotoni o elettroni della catena linfonodale mammaria interna. Dosimetria sperimentale e implicazioni cliniche.

The radiation therapy of internal mammary chain, according to many other authors, is indicated in patients with N + breast cancer or with inner quadrant disease. Since the direct field with gamma radiation seems to induce important adverse effects on myocardium, the authors were induced to check experimentally dose distributions of 12-15 MeV electron beams and compare the results to gamma photon dose distribution. Materials and dosimetric methods as well as experimental results are described. Moreover theoretic and practical point of view are discussed coming to the conclusion that electron beams are more suitable for myocardial saving. Nevertheless some technical variations are required, to maintain the typical homogeneity of photon beams.

[Postoperative radiotherapy in the treatment of breast tumors. Evaluation of a 5-year case series]. / La radioterapia post-chirurgica nel trattamento dei tumori della mammella. Valutazione di una casistica di 5 anni.

Between January 1981 and December 1985, 364 female patients underwent surgical treatment for breast cancer in Mestre General Hospital. The pathological stage of the disease was stage I in 60 patients, stage II in 215 patients, stage III A in 30 patients, stage III B in 44 patients and stage IV in 15 patients. The patients with T1-T2 N0 lesions located in the outer quadrants received no additional treatment after surgery, while the others received adjuvant therapy. The patients with stage-IV disease (M+) were treated with chemo and/or hormonotherapy. All patients were followed for an average of 33 months up to December 1986 (range 1-71 months). Local-regional relapses developed in 17 patients, 15 on the chest wall and 2 in the drainage lymph nodes (only 7 within the previously-treated area). A 5-year actuarial survival rate was observed of about 78%, and 66% of relapse-free survival, in the whole group of patients (100% and 92% in stage I; 92.5% and 76% in stage II; 51% and 33% in stage III A; 32% and 19% in stage III B; 31% in stage IV, respectively). As far as our series of patients is concerned, the massive involvement of axillary lymph nodes seems to be the most adverse prognostic factor in survival rates. Even though the short follow-up does not allow definitive conclusions to be drawn, the authors believe such loco-regional treatments as surgery and radiation therapy to be extremely important in the local control of breast cancers, as well as in the patients' survival in the long run.

Three-field isocentric technique for breast irradiation using individualized shielding blocks.

The three-field technique is the most common method used for breast and regional node treatment after conservative surgery. Several variants of this technique, which are characterized by complex geometrical problems, have been described. A possible simplification of this technique and the use of individualized shielding blocks both for anterior and for tangential fields is proposed, thus allowing for the simultaneous shielding of the half beam and the critical areas. Advantages of isocentrical techniques are thereby maintained, but the number of mechanical movements required is minimized and collimators and couch rotations are not needed. Patient set-up time is also greatly shortened. The accuracy of this technique has been verified using both photographic methods and thermoluminescent dosimetry.

[Diagnostic and therapeutic approach to lung neoplasms. Departmental experience at the Mestre Hospital]. / L'approccio diagnostico e terapeutico alle neoplasie polmonari. Esperienza dipartimentale dell'Ospedale di Mestre.

The results are reported of a multidisciplinary diagnostic and therapeutic program applied to 381 patients with lung carcinoma from 1983 through 1985 at Mestre General Hospital. Cytologic and/or histologic diagnosis was established in 95% and staging accomplished in 96% of the patients. One-hundred-twenty-nine patients with non-small cell cancer were primarily treated by surgery (lobectomy or pneumonectomy); 3-year survival of this group was 48%. Of the 45 patients with pN1 or pN2 disease, 23 were treated with postoperative adjunctive mediastinal radiotherapy (50Gy/25 F/5Wk); however, survival showed no significant difference in the two groups. Ninety-seven inoperable patients were treated by radiotherapy alone; among those receiving doses of 50-60 Gy in 5 to 6 weeks, 3-year survival was 10%. Chemotherapy (CAMP), used in 23 cases (22 stage IV, 1 stage III), showed no improvement in survival, as compared with a similar series of patients submitted to symptomatic treatment alone. Of the 27 patients affected by small-cell carcinoma, 14 were treated with an aggressive radiochemotherapy protocol and 13 with palliative radiotherapy or low-dose chemotherapy: median survival in the two groups was respectively 45 and 60 weeks. Our study demonstrates the clinical feasibility of interdisciplinary programs routinely applied to a large population of lung cancer patients, and confirms its rationale in terms of early diagnosis, improved staging, and adequate treatment.