Intracranial radiosurgery in the Netherlands. A planning comparison of available systems with regard to physical aspects and workload.

Different planning and treatment systems for intracranial stereotactic radiosurgery available in the Netherlands are compared. The systems for intracranial radiosurgery include: Gamma Knife, Cyberknife, Novalis, and Tomotherapy. Electronic data of 5 patients was transferred to all participating centres and treatment plans were generated according to 2 different prescription protocols. For this study, plans were also generated for a conventional linac. Even systems with a high resolution (Gammaknife and Novalis) have conformity indices in violation with RTOG guidelines (CI > 2.5) when target volumes of <0.5 cc are treated. For medium sized targets (0.5-1 cc) all systems performed reasonably well, but for the different systems a large range of conformity indices was seen (1.1 to 3.7). The differences are partly system dependent but depend also on specific planning choices made. For larger target volumes (> 1 cc), all systems perform well. The workload of the different techniques was comparable although the treatment times were usually longer for Gamma Knife radiosurgery. We conclude that small targets should be treated by dedicated systems, larger volumes (> 0.5-1 cc) can also be treated using conventional treatment systems equipped with a MLC.

[Treatment of patients with stage III non-small cell lung cancer: concurrent high-dose chemotherapy and radiotherapy]. / Behandeling van patiënten met niet-kleincellig longcarcinoom stadium III: gelijktijdig hooggedoseerde chemotherapie en radiotherapie.

The treatment of patients with locally advanced non-small cell lung cancer (stage III) has changed significantly in the past few years. Patients with a non-resectable stage IIIA/B tumour are given combined treatment consisting ofchemotherapy and radiotherapy. These can be administered sequentially or concurrently. It has been shown recently that concurrent chemoradiotherapy gives a survival advantage in comparison with sequential chemoradiotherapy. Cisplatin and etoposide are usually the drugs of choice for chemotherapy in patients with stage III cancer. A biologically effective dose of radiotherapy equivalent to 60-66 Gy, over a maximum of 6.5 weeks, should be given. Surgery is possible for a selected group of patients, provided a complete objective mediastinal response has been achieved after chemoradiotherapy and a complete resection appears to be technically feasible. It is recommended to apply this treatment in a research setting. High-dose concurrent chemoradiotherapy is advised as the standard treatment for stage III non-small cell lung cancer in patients in good physical condition.

Separation and characterization of oligomers by reversed-phase high-performance liquid chromatography: a study on well-defined oligothiphenes.

Reversed-phase high-performance liquid chromatography (RP-HPLC) was used for the separation of 3-hexylthiophene oligomers in the range of 3 to 30 monomeric units, while systematically varying stationary and mobile phases. A set of different columns was chosen, covering a broad range of silica types, pore sizes and bonding chemistry. Mobile phases of tetrahydrofuran (THF) combined with water, acetonitrile (ACN) or methanol (MeOH) were used. Although differences between columns were small, a higher selectivity correlated with a lower hydrophobicity parameter from the Galushko column test. The model of Jandera, based on the linear solvent strength model of Snyder, was used to describe the retention of the oligomers in gradient mode. This gave information about selectivities on different stationary phases similar to the hydrophobicity parameter. Contrary to the stationary phase, the mobile phase had a major influence on the selectivity. The THF-water combination gave much higher selectivities compared to THF combined with MeOH or ACN. Using the aqueous mobile phase even enabled separation of different isomers. Determination of thermodynamic parameters for the model compounds showed that retention of the different isomers was mainly determined by the orientation of the side chains at both ends of the chain. An additional repeating unit in the middle of the polymer backbone gave a similar contribution to retention, irrespective of the orientation of its side chain. Three model isomers were separated by preparative RP-HPLC and identified by proton nuclear magnetic resonance spectroscopy. The combination of subsequent preparative size-exclusion chromatography, RP-HPLC and matrix-assisted laser desorption ionization time-of-flight mass spectrometry enabled the identification of the two major oligomeric series in the sample as the regioregular product with one bromine end group and, in smaller amounts, a regioirregular product with two bromine end groups. reserved.

HDR brachytherapy applied to cervical carcinoma with moderate lateral expansion: modified principles of treatment.

BACKGROUND AND PURPOSE: In order to meet the deficiencies of endocavitary applications, a combined technique was introduced with the aim of achieving better target coverage for improvement of loco-regional tumour control. In high dose rate (HDR) endocavitary applications with tandem and ovoids, enlargement of the distance between the ovoids, shifting of dwell times and also optimization often fail to achieve sufficient expansion of the cervical parametrial area encompassed by the reference isodose. MATERIALS AND METHODS: The Deventer method, whereby HDR endocavitary and HDR interstitial brachytherapy are applied in the same session, was applied for tumours with a lateral expansion of 25 mm or more from the axis of the cervical canal. For the addition of HDR interstitial brachytherapy, each ovoid was provided with a channel which allowed insertion of an afterloading needle into the cervix up to a fixed depth. The dose specifications and dosimetry in neighbouring organs are presented in detail. RESULTS: Seventy-six combined applications were given to 41 patients. The follow-up averaged at 23 months, with a maximum of 59 months. No severe early or persistent late complications were observed. In stage IIB tumours, the most important evaluation of the merits of this technique, the disease-free 3-year survival determined with the Kaplan-Meier method was 75% (n=20). CONCLUSIONS: The Deventer method of HDR endocavitary and HDR interstitial brachytherapy applied in the same session is a feasible method for enlargement of the reference isodose envelope in the cervical parametrial area. The 3-year disease-free survival in stage IIB patients and the low complication rates in all stages together, justify its continuation.

The effect of a single fraction compared to multiple fractions on painful bone metastases: a global analysis of the Dutch Bone Metastasis Study.

PURPOSE: To answer the question whether a single fraction of radiotherapy that is considered more convenient to the patient is as effective as a dose of multiple fractions for palliation of painful bone metastases. PATIENTS: 1171 patients were randomised to receive either 8 Gy x 1 (n = 585) or 4 Gy x 6 (n = 586). The primary tumour was in the breast in 39% of the patients, in the prostate in 23%, in the lung in 25% and in other locations in 13%. Bone metastases were located in the spine (30%), pelvis (36%), femur (10%), ribs (8%), humerus (6%) and other sites (10%). METHOD: Questionnaires were mailed to collect information on pain, analgesics consumption, quality of life and side effects during treatment. The main endpoint was pain measured on a pain scale from 0 (no pain at all) to 10 (worst imaginable pain). Costs per treatment schedule were estimated. RESULTS: On average, patients participated in the study for 4 months. Median survival was 7 months. Response was defined as a decrease of at least two points as compared to the initial pain score. The difference in response between the two treatment groups proved not significant and stayed well within the margin of 10%. Overall, 71% experienced a response at some time during the first year. An analysis of repeated measures confirmed that the two treatment schedules were equivalent in terms of palliation. With regard to pain medication, quality of life and side effects no differences between the two treatment groups were found. The total number of retreatments was 188 (16%). This number was 147 (25%) in the 8 Gy x 1 irradiation group and 41 (7%) in the 4 Gy x 6 group. It was shown that the level of pain was an important reason to retreat. There were also indications that doctors were more willing to retreat patients in the single fraction group because time to retreatment was substantially shorter in this group and the preceding pain score was lower. Unexpectedly, more pathological fractures were observed in the single fraction group, but the absolute percentage was low. In a cost-analysis, the costs of the 4 Gy x 6 and the 8 Gy x 1 treatment schedules were calculated at 2305 and 1734 Euro respectively. Including the costs of retreatment reduced this 25% cost difference to only 8%. The saving of radiotherapy capacity, however, was considered the major economic advantage of the single dose schedule. CONCLUSION: The global analysis of the Dutch study indicates the equality of a single fraction as compared to a 6 fraction treatment in patients with painful bone metastases provided that 4 times more retreatments are accepted in the single dose group. This equality is also shown in long term survivors. A more detailed analysis of the study is in progress.