Eckart Richter

Postoperative neoadjuvant chemotherapy before radiotherapy as compared to immediate radiotherapy followed by maintenance chemotherapy in the treatment of medulloblastoma in childhood: results of the german prospective randomized trial hit ’91

Purpose: The German Society of Pediatric Hematology and Oncology (GPOH) conducted a randomized, prospective, multicenter trial (HIT ’91) in order to improve the survival of children with medulloblastoma by using postoperative neoadjuvant chemotherapy before radiation therapy as opposed to maintenance chemotherapy after immediate postoperative radiotherapy. Methods and Materials: Between 1991 and 1997, 158 patients were enrolled and 137 patients randomized. Seventy-two patients were allocated to receive neoadjuvant chemotherapy before radiotherapy (arm I, investigational). Chemotherapy consisted of ifosfamide, etoposide, intravenous high-dose methotrexate, cisplatin, and cytarabine given in two cycles. In arm II (standard arm), 65 patients were assigned to receive immediate postoperative radiotherapy, with concomitant vincristine followed by 8 cycles of maintenance chemotherapy consisting of cisplatin, CCNU, and vincristine (“Philadelphia protocol”). All patients received radiotherapy to the craniospinal axis (35.2 Gy total dose, 1.6 Gy fractionated dose / 5 times per week followed by a boost to posterior fossa with 20 Gy, 2.0 Gy fractionated dose). Results: During chemotherapy Grade III/IV infections were predominant in arm I (40%). Peripheral neuropathy and ototoxicity were prevailing in arm II (37% and 34%, respectively). Dose modification was necessary in particular in arm II (63%). During radiotherapy acute toxicity was mild in the majority of patients and equally distributed in both arms. Myelosuppression led to a mean prolongation of treatment time of 11.5 days in arm I and 7.5 days in arm II, and interruptions in 35% of patients in arm I. Quality control of radiotherapy revealed correct treatment in more than 88% for dose prescription, more than 88% for coverage of target volume, and 98% for field matching. At a median follow-up of 30 months (range 1.4–62 months), the Kaplan-Meier estimates for relapse-free survival at 3 years for all randomized patients were 0.70 ± 0.08; for patients with residual disease: 0.72 ±0.06; without residual disease: 0.68 ± 0.09; M0: 0.72 ± 0.04; M1: 0.65 ± 0.12; and M2/3: 0.30 ± 0.15. For all randomized patients without M2/3 disease: 0.65± 0.05 (arm I) and 0.78 ± 0.06 (arm II) (p < 0.03); patients between 3 and 5.9 years: 0.60 ± 0.13 and 0.64 ± 0.14, respectively, but patients between 6 and 18 years: 0.62 ± 0.09 and 0.84 ± 0.08, respectively (p < 0.03). In a univariate analysis the only negative prognostic factors were M2/3 disease (p < 0.002) and an age of less than 8 years (p < 0.03). Conclusions: Maintenance chemotherapy would seem to be more effective in low-risk medulloblastoma, especially in patients older than 6 years of age. Neoadjuvant chemotherapy was accompanied by increased myelotoxicity of the subsequent radiotherapy, causing a higher rate of interruptions and an extended overall treatment time. Delayed and/or protracted radiotherapy may therefore have a negative impact on outcome. M2/3 disease was associated with a poor survival in both arms, suggesting the need for a more intensive treatment. Young age and M2/3 stage were negative prognostic factors in medulloblastoma, but residual or M1 disease was not, suggesting a new stratification system for risk subgroups. High quality of radiotherapy may be a major contributing factor for the overall outcome.

The hypoxia-inducible factor-1α is a negative factor for tumor therapy

Tumor hypoxia negatively regulates cell growth and causes a more malignant phenotype by increasing the expression of genes encoding angiogenic, metabolic and metastatic factors. Of clinical importance, insufficient tumor oxygenation affects the efficiency of chemotherapy and radiotherapy by poorly understood mechanisms. The hypoxia-inducible factor (HIF)-1 is a master transcriptional activator of oxygen-regulated genes and HIF-1 is constitutively upregulated in several tumor types. HIF-1 might thus be implicated in tumor therapy resistance. We found that transformed mouse embryonic fibroblasts deficient for HIF-1α are more susceptible to the treatment with carboplatin, etoposide and ionizing radiation than wild-type cells. Increased cell death in HIF-1α-deficient cells was because of apoptosis and did not involve p53 induction. Tumor chemotherapy of experimental fibrosarcoma in immunocompromised mice with carboplatin and etoposide confirmed the enhanced susceptibility of HIF-1α-deficient cells. Agents that did not cause DNA double-strand breaks, such as DNA-synthesis inhibitors or a DNA single-strand break-causing agent equally impaired cell growth, independent of the HIF-1α genotype. Functional repair of a fragmented reporter gene was decreased in HIF-1α-deficient cells. Thus, hypoxia-independent basal HIF-1α expression in tumor cells, as known from untransformed embryonic stem cells, is sufficient to induce target gene expression, probably including DNA double-strand break repair enzymes.

Randomized phase III trial of postoperative radiochemotherapy +/- amifostine in head and neck cancer. Is there evidence for radioprotection?

Purpose: Experimental and clincial data suggest a reduction of radiation-induced acute toxicity by amifostine (A). We investigated this issue in a randomized trial comparing radiochemotherapy (RT + CT) versus radiochemotherapy plus amifostine (RC + CT + A) in patients with head and neck cancer. Patients and Methods: 56 patients with oro-/hypopharynx or larynx cancer (T1–2 N1–2 G3, T3–4 N0–2 G1–3) were randomized to receive RC + CT alone or RC + CT + A. Patients were irradiated up to 60 Gy (R0) or 70 Gy (R1/2) and received chemotherapy (70 mg/m2 carboplatin, day 1–5 in week 1 and 5 of radiotherapy). 250 mg amifostine were applied daily before each radiotherapy session. Acute toxicity was evaluated according to the Common Toxicity Criteria (CTC). As for acute xerostomia, patients with laryngeal cancer were excluded from evaluation. Results: 50 patients were evaluable (25 patients in the RC + CT, 25 patients in the RC + CT + A group). Clinical characteristics were well balanced in both treatment groups. Amifostine provided reduction in acute xerostomia and mucositis but had no obvious influence on Karnofsky performance status, body weight, cutaneous side effects, and alopecia. The differences between both groups were statistically significant for acute xerostomia and nonsignificant, but with a trend for mucositis. Conclusions: According to our results, there is a radioprotective effect on salivary glands and a potential effect on oral mucosa by amifostine in postoperative radiotherapy combined with carboplatin. To improve the radio- and chemoprotective effects of amifostine in clinical practice, the application of a higher dose (> 250 mg) seems to be necessary.Hintergrund: Experimentelle und klinische Daten legen eine Reduktion der akuten radiogenen Nebenwirkungen durch Amifostin (A) nahe. Wir untersuchten diese Frage in einer randomisierten Studie mit dem Vergleich von Radiochemotherapie (RC + CT) versus Radiochemotherapie + Amifostin (RC + CT + A) bei HNO-Tumorpatienten. Patienten und Methodik: 56 Patienten mit Oro-/Hypopharynx- oder Larynxkarzinom (T1–2 N1–2 G3, T3–4 N0–2 G1–3) wurden randomisiert behandelt. Sie wurden mit 60 Gy (R0) oder 70 Gy (R1/2) bestrahlt und erhielten Zytostatika (70 mg/m2 Carboplatin, Tag 1–5 in Woche 1 und 5 der Radiatio). Vor jeder Strahlentherapiesitzung wurden ggf. 250 mg Amifostin appliziert. Die akuten Nebenwirkungen wurden nach den CTC-Kriterien bewertet. Bezüglich der Xerostomie wurden die Larynxkarzinompatienten von der Analyse ausgeschlossen. Ergebnisse: 50 Patienten waren auswertbar (25 Patienten mit RC + CT, 25 Patienten mit RC + CT + A). Die klinischen Parameter waren in beiden Gruppen sehr ähnlich. Amifostin reduzierte die Xerostomie und die Mukositis, hatte aber keinen Einfluss auf den Leistungszustand, das Körpergewicht, kutane Nebenwirkungen und Alopezie. Die Unterschiede zwischen beiden Gruppen waren statistisch signifikant bezüglich der Xerostomie, nicht jedoch für die Mukositis, wenn auch ein Trend zugunsten der Amifostin-Gruppe vorhanden war. Schlussfolgerungen: Wir sahen einen radioprotektiven Effekt von Amifostin auf die Speicheldrüsen und einen möglichen Effekt auf die Mundhöhlenschleimhaut bei einer postoperativen Radiochemotherapie mit Carboplatin. Um die radio- und chemoprotektive Wirkung von Amifostin klinisch zu verbessern, müssen vermutlich höhere Dosen als 250 mg verwendet werden.

Randomized Phase III Trial of Postoperative Radiochemotherapy ± Amifostine in Head and Neck Cancer

Purpose: Experimental and clincial data suggest a reduction of radiation-induced acute toxicity by amifostine (A). We investigated this issue in a randomized trial comparing radiochemotherapy (RT + CT) versus radiochemotherapy plus amifostine (RC + CT + A) in patients with head and neck cancer. Patients and Methods: 56 patients with oro-/hypopharynx or larynx cancer (T1–2 N1–2 G3, T3–4 N0–2 G1–3) were randomized to receive RC + CT alone or RC + CT + A. Patients were irradiated up to 60 Gy (R0) or 70 Gy (R1/2) and received chemotherapy (70 mg/m2 carboplatin, day 1–5 in week 1 and 5 of radiotherapy). 250 mg amifostine were applied daily before each radiotherapy session. Acute toxicity was evaluated according to the Common Toxicity Criteria (CTC). As for acute xerostomia, patients with laryngeal cancer were excluded from evaluation. Results: 50 patients were evaluable (25 patients in the RC + CT, 25 patients in the RC + CT + A group). Clinical characteristics were well balanced in both treatment groups. Amifostine provided reduction in acute xerostomia and mucositis but had no obvious influence on Karnofsky performance status, body weight, cutaneous side effects, and alopecia. The differences between both groups were statistically significant for acute xerostomia and nonsignificant, but with a trend for mucositis. Conclusions: According to our results, there is a radioprotective effect on salivary glands and a potential effect on oral mucosa by amifostine in postoperative radiotherapy combined with carboplatin. To improve the radio- and chemoprotective effects of amifostine in clinical practice, the application of a higher dose (> 250 mg) seems to be necessary.Hintergrund: Experimentelle und klinische Daten legen eine Reduktion der akuten radiogenen Nebenwirkungen durch Amifostin (A) nahe. Wir untersuchten diese Frage in einer randomisierten Studie mit dem Vergleich von Radiochemotherapie (RC + CT) versus Radiochemotherapie + Amifostin (RC + CT + A) bei HNO-Tumorpatienten. Patienten und Methodik: 56 Patienten mit Oro-/Hypopharynx- oder Larynxkarzinom (T1–2 N1–2 G3, T3–4 N0–2 G1–3) wurden randomisiert behandelt. Sie wurden mit 60 Gy (R0) oder 70 Gy (R1/2) bestrahlt und erhielten Zytostatika (70 mg/m2 Carboplatin, Tag 1–5 in Woche 1 und 5 der Radiatio). Vor jeder Strahlentherapiesitzung wurden ggf. 250 mg Amifostin appliziert. Die akuten Nebenwirkungen wurden nach den CTC-Kriterien bewertet. Bezüglich der Xerostomie wurden die Larynxkarzinompatienten von der Analyse ausgeschlossen. Ergebnisse: 50 Patienten waren auswertbar (25 Patienten mit RC + CT, 25 Patienten mit RC + CT + A). Die klinischen Parameter waren in beiden Gruppen sehr ähnlich. Amifostin reduzierte die Xerostomie und die Mukositis, hatte aber keinen Einfluss auf den Leistungszustand, das Körpergewicht, kutane Nebenwirkungen und Alopezie. Die Unterschiede zwischen beiden Gruppen waren statistisch signifikant bezüglich der Xerostomie, nicht jedoch für die Mukositis, wenn auch ein Trend zugunsten der Amifostin-Gruppe vorhanden war. Schlussfolgerungen: Wir sahen einen radioprotektiven Effekt von Amifostin auf die Speicheldrüsen und einen möglichen Effekt auf die Mundhöhlenschleimhaut bei einer postoperativen Radiochemotherapie mit Carboplatin. Um die radio- und chemoprotektive Wirkung von Amifostin klinisch zu verbessern, müssen vermutlich höhere Dosen als 250 mg verwendet werden.

Local hyperthermia, radiation, and chemotherapy in recurrent breast cancer is feasible and effective except for inflammatory disease

PURPOSE To investigate the feasibility and effectiveness of radiochemothermotherapy (triple-modality therapy) in patients with inoperable recurrent breast cancer. PATIENTS AND METHODS Patients with inoperable recurrent lesions, World Health Organization (WHO) performance status of 2 or greater, life expectancy of more than 3 months, adequate bone marrow, hepatic and renal function were eligible for this Phase I/II study. Conventionally fractionated or hyperfractionated radiotherapy (RT) was performed. Once-weekly local hyperthermia (HT) combined with chemotherapy (CT; epirubicin 20 mg/m(2), ifosfamide 1.5 g/m(2)) was applied within 30 min after RT. RESULTS Twenty-five patients, all heavily pretreated (18/25 preirradiated), received a mean total dose of 49 Gy. The median number of HT/CT sessions was 4. Skin toxicity was low, whereas bone marrow toxicity was significant (leucopenia Grade 3/4 in 14/1 patients). The overall response rate was 80% with a complete response (CR) rate of 44%. Response rates in patients with noninflammatory disease (n = 14; CR 10 patients, partial response [PR] 3 patients) were far better than in patients with inflammatory disease (n = 11; CR 1 patient, PR 6 patients). CONCLUSIONS In patients with recurrent breast cancer, triple-modality therapy is feasible with acceptable toxicity. High remission rates can be achieved in noninflammatory disease, however, local control is limited to a few months. Whether the addition of chemotherapy has a clear-cut advantage to radiothermotherapy alone remains an open question.

Salivary gland scintigraphy using technetium-99m-pertechnetate after autotransplantation of the submandibular salivary gland in the correction of dry eye

Abstract. The aim of the study was to determine whether salivary gland scintigraphy using technetium-99m pertechnetate is suitable for checking the vitality and function after autotransplantation of the submandibular salivary gland in patients with dry eye syndrome. To this end, 56 scintigraphic studies in 20 patients have so far been performed. In addition, these scans were evaluated by a region of interest (ROI) technique in order to examine tracer uptake in the early and late stages after surgery. We have been able to prove that in this special respect, too, the salivary gland scintigraphy is suitable for assessing reliably the vitality and function of the transplanted gland. The secretion into the eye and thus the patency of the efferent duct can also be displayed. This proved to be particularly valuable in those cases in which at first no secretion could be seen in the clinical examination. In patients with uncertain excretory function, we were able to distinguish between non-vitality and lack of patency of the secretory duct. Using ROI evaluation, no significant decrease in the salivary function has been detected in long-term follow-up, now extending to 1 year after surgery.

Increased Radioiodine Uptake of Thyroid Cell Cultures after External Irradiation

Background:Radioiodine uptake (RIU) is one of the main prognostic factors for curative results of radioiodine therapy in patients with differentiated thyroid cancer. Some days after application of 131I, the uptake of a subsequent administration of radioiodine was found to be reduced. In contrast, early after irradiation with high-energy photons glucose and amino acid uptake were observed to be increased. Effects of external irradiation on RIU of thyrocytes using high-energy photons have not been investigated so far.Material and Methods:Two different cell lines (FRTL-5 and ML-1 cells) derived from thyroid tissue were studied in vitro. Cell lines were either incubated with 131I only (controls) or additionally irradiated with single doses of 6 or 10 Gy of high-energy photons using a linear accelerator. Cell number and RIU were determined 24–96 h after 131I application. RIU measurements were repeated after application of sodium perchlorate in excess to investigate specificity of the uptake. Statistical analyses were performed using non-parametric tests.Results:Incubation with radioiodine as well as irradiation with high-energy photons slowed down proliferation in investigated cell lines significantly. Irradiation with solely 131I resulted in stable or slightly decreased iodide uptake. Compared to those cells, the RIU increased significantly in externally irradiated cells, i. e., additional irradiation with 10 Gy resulted in an almost threefold increase of RIU in FRTL-5 after 72 h. The increase of RIU after irradiation was dose-dependent in both cell lines and could be blocked by perchlorate excess.Conclusion:It could be demonstrated that external irradiation increases RIU in thyroid cell cultures early after irradiation. The increase was dose-dependent and specific, as it could be blocked by perchlorate. This effect appears to be similar to the increase of other actively transported substances after irradiation with high-energy photons. Therefore, the results of this study may contribute to the knowledge of a generalized irradiation-induced mechanism which causes the activation of different cellular transporters. The clinical impact of these findings on combined therapy concepts has to be investigated in further experiments.Hintergrund:Der Radioiod-Uptake (RIU) ist ein wesentlicher prognostischer Faktor für den kurativen Erfolg der Radioiodtherapie bei Patienten mit differenziertem Schilddrüsenkarzinom. Es konnte gezeigt werden, dass einige Tage nach 131I-Gabe der Uptake bei einer erneuten Radioiodapplikation deutlich vermindert war. Im Gegensatz dazu wurde eine Zunahme des Glukose- und Aminosäure-Uptakes kurz nach der Bestrahlung mit hochenergetischen Photonen beschrieben. Effekte einer externen Bestrahlung mit hochenergetischen Photonen auf den RIU von Thyreozyten sind bisher noch nicht untersucht worden.Material und Methodik:Die Untersuchungen wurden in vitro an zwei unterschiedlichen Zelllinien (FRTL-5- und ML-1-Zellen) thyreoidalen Ursprungs durchgeführt. Die Zellkulturen wurden entweder nur mit Radioiod inkubiert (Kontrollen) oder zusätzlich einzeitig mit Hilfe eines Linearbeschleunigers mit 6 oder 10 Gy bestrahlt. Die Bestimmung der Zellzahl und des RIU erfolgte 24–96 h nach der 131I-Applikation. Die Messungen wurden nach Zugabe von Natriumperchlorat im Überschuss wiederholt. Statistische Analysen erfolgten mittels nichtparametrischer Tests.Ergebnisse:Die Proliferation der untersuchten Zelllinien wurde sowohl durch die Inkubation mit Radioiod als auch durch die Bestrahlung signifikant vermindert. Die Bestrahlung mit 131I allein führte zu gleichbleibendem oder leicht vermindertem Iodid-Uptake. Verglichen mit diesen Zellen erhöhte die externe Bestrahlung den RIU signifikant. So konnte bei FRTL-5-Zellen durch die zusätzliche Bestrahlung mit 10 Gy der RIU nach 72 h beinahe verdreifacht werden. Der Anstieg des RIU nach Bestrahlung war bei beiden Zelllinien dosisabhängig und konnte durch einen Überschuss an Perchlorat blockiert werden.Schlussfolgerung:In dieser Studie konnte gezeigt werden, dass eine externe Bestrahlung mit hochenergetischen Photonen zu einem Anstieg des RIU von Schilddrüsen-Zellkulturen führt. Dieser Anstieg war dosisabhängig und spezifisch, da er durch Perchlorat geblockt werden konnte. Dieser Effekt weist Ähnlichkeiten zum Anstieg anderer aktiv transportierter Substanzen nach Bestrahlung auf. Die Ergebnisse dieser Studie liefern einen Beitrag zur Kenntnis eines generalisierten Mechanismus, welcher auf eine Aktivierung unterschiedlicher zellulärer Transporter nach Bestrahlung mit hochenergetischen Photonen hinweist. Die klinische Relevanz dieser Ergebnisse für kombinierte Therapieverfahren sollte in weiteren Untersuchungen geklärt werden.

Reduced radioiodine uptake at increased iodine intake and 131I-induced release of “cold” iodine stored in the thyroid

AIM The extent of urinary iodine excretion (UIE) provides information about iodine supply and release. In the present study we investigated correlations between UIE and radioiodine uptake (RIU) as well as effects of radioiodine therapy on UIE in patients with autonomous goitre. PATIENTS, METHODS In 197 consecutive patients with thyroid autonomy, UIE was measured twice during radioiodine test (RITe) and correlated with RIU. In 98 of these patients, thyroglobulin and thyroid volume (V) were determined prior to therapy. Individual changes in urinary iodine excretion (DeltaUIE) and TG (DeltaTG) could be investigated four weeks (4W) and six months (6M) after radioiodine therapy. Additionally, DeltaV was determined 6M after therapy. DeltaUIE, DeltaTG and DeltaV were correlated with target dose and target volume. RESULTS Patients with higher iodine excretion exhibited significantly lower thyroidal radioiodine uptake values. Twofold increased UIE prior to therapy decreased radioiodine uptake by 25%. Compared with pretherapeutic values, UIE and TG were significantly increased four weeks after radioiodine therapy (p < 0.001). Median values of both parameters were found to be doubled. The product of target dose and target volume was not only correlated with a decrease of thyroid volume 6M after therapy, but also with an increase of UIE and TG in the early phase after therapy. CONCLUSIONS It was confirmed that UIE during RITe is a measure for iodine intake and can be used to investigate the competition between stable iodine and radioiodine. The increase of UIE and TG four weeks after therapeutic administration of radioiodine can be explained by disintegrated thyroid follicles. The therapy-induced iodine release may be one important cause for the development of hyperthyroidism in some patients during the first weeks after radioiodine therapy. It may contribute to the known decrease of radioiodine uptake after preapplications of 131I in various thyroid diseases.

Spinale Metastasierung bei malignen Gliomen

PURPOSE Extracranial metastases of malignant gliomas are rare. We report 2 cases with spinal metastases in patients suffering from glioma. PATIENTS AND METHOD Two patients (33 and 57 years old) developed spinal canal metastases of a glioblastoma multiforme and anaplastic astrocytoma Grade III respectively 25 and 9 months after surgical resection and radiotherapy. Both metastases were confirmed pathohistologically. RESULTS Intraspinal metastases were irradiated with a total dose of 12.6 Gy and 50 Gy. Treatment withdrawal was necessary in one patient due to reduced clinical condition. Regression of neurological symptoms was observed in the second patient. CONCLUSIONS Spinal spread of malignant glioma should be considered during care and follow-up in glioma patients with spinal symptoms.ZusammenfassungHintergrundMaligne Gliome metastasieren äußerst selten extrakraniell. Wir stellen zwei Fälle einer spinalen Filialisierung bei Gliompatienten vor.Patientengut und MethodeZwei Patienten (33 und 57 Jahre alt) entwickelten 25 bzw. neun Monate nach Resektion und postoperativer Radiatio eines Glioblastoma multiforme und eines anaplastischen Astrozytoms WHO-Grad III histologisch gesicherte intraspinale Metastasen, welche durch Sensibilitätsstörungen der Beine symptomatisch wurden.ErgebnisseDie intraspinalen Filiae wurden mit 12,6 Gy bzw. 50 Gy bestrahlt. Bei einem Patienten mußte die Radiatio wegen zunehmender Verschlechterung des Allgemeinzustandes, abgebrochen werden bei dem zweiten Patienten besserte sich die neurologische Symptomatik.SchlußfolgerungBei der Betreuung von Gliompatienten sollte, insbesondere in der Nachsorge, an die Möglichkeit der spinalen Metastasierung mit entsprechender Symptomatik gedacht werden.AbstractPurposeExtracranial metastases of malignant gliomas are rare. We report 2 cases with spinal metastases in patients suffering from glioma.Patients and MethodTwo patients (33 and 57 years old) developed spinal canal metastases of a glioblastoma multiforme and anaplastic astrocytoma Grade III respectively 25 and 9 months after surgical resection and radiotherapy. Both metastases were confirmed pathohistologically.ResultsIntraspinal metastases were irradiated with a total dose of 12.6 Gy and 50 Gy. Treatment withdrawal was necessary in one patient due to reduced clinical condition. Regression of neurological symptoms was observed in the second patient.ConclusionsSpinal spread of malignant glioma should be considered during care and follow-up in glioma patients with spinal symptoms.

Clinical use of a simulation-multileaf collimator

BackgroundAt the University of Lübeck, radiotherapy is delivered by a 6/18-MV linear accelerator. Using the integrated multileaf collimator, irradiation of individually shaped treatment fields is possible in place of alloy blocks. Due to unsatisfactory pretherapeutic review of the radiation-field-specific multileaf collimator (MLC) configuration, we developed a simulation-multileaf collimator (SMLC) and assessed its feasibility at different tumor sites.Material and MethodsThe SMLC is made of a perspex carrier with 52 horizontal sliding leaves. The position of each leaf is calculated by a 3D treatment-planning computer. The technician manually adjusts the leaves according to the beams-eye-view plot of the planning computer. Consequently, the SMLC is mounted on the therapy simulator at a distance of 64.8 cm from the focus. The treatment fields and the position of the leaves are documented by X-ray films.ResultsUsing the SMLC, radiation oncologists are able to review exactly the leaf configuration of each MLC-shaped radiation field and to correlate the MLC-shaped radiation field with the treated volume, the organs at risk and the port films acquired by the Portal Vision® system.ConclusionThe SMLC is a new tool to review radiation planning that uses an MLC in daily routine. The use of the SMLC improves the documentation and the quality assurance. It accelerates the treatment field review at the linear accelerator by comparing the SMLC simulator films with the portal images.ZusammenfassungHintergrundSeit 1994 werden Patienten an der Lübecker Universitätsklinik für Strahlentherapie und Nuklearmedizin an einem Linearbeschleuniger bestrahlt, der mit einem Multileaf-Kollimator ausgerüstet ist. Dieser ermöglicht die Bestrahlung individuel geformter Zielvolumina ohne gegossene Individualsatelliten. Wegen der unzureichenden prätherapeutischen Kontrolle der Lamellenkonfiguration des Multileaf-Kollimators wurde ein Simulations-Multileaf-Kollimator (SMLC) entwickelt und dessen Anwendbarkeit bei verschiedenen Tumorlokalisationen überprüft.Material und Methode nDer Simulations-Multileaf-Kollimator besteht aus einem Plexiglasträger mit 52 horizontal beweglichen Lamellen. Die Position jeder einzelnen Lamelle wird vom 3D-Planungscomputer berechnet. Die Lamellen werden entsprechend dem Beams-Eye-View-Ausdruck des Planungsrechners manuell eingestellt. Anschließend wird der Simulations-Multileaf-Kollimator in einem Abstand von 64,8 cm vom Fokus des Simulators in den Strahlengang eingeschoben. Die Bestrahlungsfelder und die Lamellenkonfiguration werden mit Röntgenfilmen dokumentiert.ErgebnisseDer Strahlentherapeut kann mit Hilfe des Simulations-Multileaf-Kollimators die Lamellenkonfiguration MLC-konfigurierter Bestrahlungsfelder exakt beurteilen und diese mit den Portal-Imaging-Verifikationsaufnahmen korrelieren.SchlußfolgerungDer neu entwickelte Simulations-Multileaf-Kollimator ermöglicht in der täglichen Routine der Therapiesimulation die sichere Kontrolle und Dokumentation der Lamellenkonfiguration des Multileaf-Kollimators. Die Kontrolle der Bestrahlungsfelder am Beschleuniger wird durch den Vergleich der SMLC-Röntgenfilme mit den Verifikationsaufnahmen beschleunigt.