Thomas Auberger

Treatment planning comparison of conventional, 3D conformal, and intensity-modulated photon (IMRT) and proton therapy for paranasal sinus carcinoma.

PURPOSE To determine the potential improvements in patients with paranasal sinus carcinoma by comparing proton and intensity-modulated radiotherapy (IMRT) with conventional and conformal photon treatment planning techniques. METHODS AND MATERIALS In 5 patients, comparative treatment planning was performed by comparing proton plans and related conventional, conformal, and IMRT photon plans. The evaluations analyzed dose-volume histogram findings of the target volumes and organs at risk (OARs, i.e., pituitary gland, optical pathway structures, brain, nontarget tissue). RESULTS The mean and maximal doses, dose inhomogeneities, and conformity indexes for the planning target volumes were comparable for all techniques. Photon plans resulted in greater volumes of irradiated nontarget tissues at the 10-70% dose level compared with the corresponding proton plans. The volumes thereby increased by a factor of 1.3-3.1 for conventional, 1.1-3.8 for conformal, and 1.1-3.7 for IMRT. Compared with conventional techniques, conformal and IMRT photon treatment planning options similarly reduced the mean dose to the OARs. The use of protons further reduced the mean dose to the OARs by up to 65% and 62% compared with the conformal and IMRT technique, respectively. CONCLUSION Compared with conventional treatment techniques, conformal RT and IMRT similarly enabled dose reductions to the OARs. Additional improvements were obtained using proton-based treatment planning modalities.

Comparative treatment planning on localized prostate carcinoma : Conformal photon- versus proton-based radiotherapy

Purpose:To assess the potential benefit of proton–beam therapy in comparison to 3–D conformal photon therapy and photon– based intensity–modulated radiotherapy (IMRT) in prostate carcinoma for various stages of disease.Material and Methods:In five patients a 3–D conformal proton–based (two lateral beams) irradiation technique was compared with 3–D conformal photon–beam radiotherapy (four–field box) and IMRT (seven beams). For each patient different target volumes (CTVs) were defined according to early, intermediate and advanced stages of disease: CTV I consisted of the prostate gland, CTV II encompassed prostate and basis of seminal vesicles, and CTV III the prostate and seminal vesicles. Corresponding planning target volumes PTV I–III were defined by uniformly adding a margin of 5 mm to CTV I–III. Dose–volume histograms (DVHs) were analyzed for the different PTVs and various organs at risk (OARs), i.e., rectal wall, bladder, both femoral heads. In addition, maximum and mean doses were derived for the various structures and irradiated non–target tissue volumes were compared for PTV I–III and the different irradiation techniques. Finally, dose conformity and target dose homogeneity were assessed.Results:With photon– and proton–based radiotherapy techniques similar dose distributions were determined for PTV I–III: mean and maximum PTV dose values were between 99–104% and 102–107% of the normalized total doses (70 Gy), respectively. Conformity indices varied from 1.4 to 1.5 for the photon techniques, whereas for proton–beam radiotherapy values ranged from 1.1 to 1.4. Both the 3–D conformal and the IMRT photon treatment technique resulted in increased mean doses (~ 40–80%) for OARs when compared to protons. With both photon techniques non–target tissue volumes were irradiated to higher doses (mean dose difference ≥ 70%) compared to proton–beam radiotherapy. Differences occurred mainly at the low and medium dose levels, whereas in high dose levels similar values were obtained. In comparison to conformal 3–D treatments IMRT reduced doses to OARs in the medium dose range, especially for the rectal wall.Conclusion:IMRT enabled dose reductions to OARs in the medium dose range compared to 3–D conformal radiotherapy. A rather simple two–field proton–based treatment technique further reduced doses to OARs compared to photon–beam radiotherapy. The advantageous dose distribution of proton–beam therapy for prostate cancer may result in reduced side effects, which needs to be confirmed in clinical studies.Ziel:Im Rahmen einer planungstechnischen Studie wurde für die Behandlung des primären Prostatakarzinoms die Dosisverteilung einer konformalen Protonentechnik mit intensitätsmodulierten (IMRT) und konformalen Photonentechniken verglichen und analysiert. Material und Methodik:Bei fünf Patienten wurde eine konformale Zwei–Felder–Protonentechnik mit einer konformalen Photonentechnik (Vier–Felder–Becken–Box) und einer Sieben–Felder–IMRT–Technik verglichen. Dabei wurden für jeden Patienten entsprechend frühen, intermediären sowie fortgeschrittenen Tumorstadien verschiedene Zielvolumina (CTV) definiert; CTV I: Prostata, CTV II: Prostata und Samenblasenbasis, CTV III: Prostata und Samenblasen. Für die Planungszielvolumina PTV I–III wurde jeweils ein isotroper Sicherheitssaum von 5 mm gewählt. Mittels Dosis–Volumen–Histogramm–(DVH–)Auswertung wurden mittlere und maximale Dosiswerte im Bereich der unterschiedlichen PTV sowie der Risikoorgane (Rektumwand, Harnblase, Hüftköpfe beidseits) verglichen. Zusätzlich wurden die Volumina des bestrahlten Normalgewebes, der PTV und Risikoorgane in unterschiedlichen Dosisbereichen bewertet.Ergebnisse:Die Dosisverteilungen in PTV I–III zeigten für die unterschiedlichen Planungsvarianten mit mittleren Dosen von 99–104% bzw. maximalen Dosiswerten von 102–107% (normiert auf Gesamtdosis 70 Gy) vergleichbare Werte. Die Konformalitätsindizes variierten zwischen 1,4 und 1,5 für die Photonentechniken und zwischen 1,1 und 1,4 für die Protonentherapie. Im Vergleich zur Protonentherapie ergaben sich bei den Photonentechniken erhöhte mittlere Dosiswerte (~ 40–80%) für die evaluierten Risikoorgane, sowie ein Anstieg (Differenz mittlere Dosis ≥ 70%) des bestrahlten Normalgewebevolumens. Die Unterschiede zwischen den Photonen– und Protonentechniken dominierten in den niedrigen und mittleren Dosisbereichen, während im Hochdosisbereich vergleichbare Dosisverteilungen erzielt wurden. Beim Vergleich der konformalen Photonentherapie mit der IMRT zeigte Letztere eine geringere Risikoorganbelastung im mittleren Dosisbereich, im Speziellen im Bereich der Rektumwand.Schlussfolgerung:Im Vergleich zur 3–D–gestützten konformalen Photonentherapie konnte mit Hilfe der IMRT die Dosisbelastung an den Risikoorganen in den mittleren Dosisbereichen reduziert werden. Der Einsatz einer Zwei–Felder–Protonentechnik führte zu einer weiteren Dosisreduktion in den Risikoorganen. Diese verbesserte Dosisverteilung von Protonen bei der Behandlung des primären Prostatakarzinoms könnte zu einer Reduktion therapieassoziierter Nebenwirkungen führen, was in zukünftigen klinischen Studien zu belegen ist.

Reproducibility of Patient Positioning for Fractionated Extracranial Stereotactic Radiotherapy Using a Double-Vacuum Technique

Background and Purpose:Precise reproducible patient positioning is a prerequisite for conformal fractionated radiotherapy. A fixation system based on double-vacuum technology is presented which can be used for conventional as well as hypofractionated stereotactic extracranial radiotherapy.Material and Methods:To form the actual vacuum mattress, the patient is pressed into the mattress with a vacuum foil which can also be used for daily repositioning and fixation. A stereotactic frame can be positioned over the region of interest on an indexed base plate. Repositioning accuracy was determined by comparing daily, pretreatment, orthogonal portal images to the respective digitally reconstructed radiographs (DRRs) in ten patients with abdominal and pelvic lesions receiving extracranial fractionated (stereotactic) radiotherapy. The three-dimensional (3-D) vectors and 95% confidence intervals (CI) were calculated from the respective deviations in the three axes. Time required for initial mold production and daily repositioning was also determined.Results:The mean 3-D repositioning error (187 fractions) was 2.5 ± 1.1 mm. The largest single deviation (10 mm) was observed in a patient treated in prone position. Mold production took an average of 15 min (10–30 min). Repositioning times are not necessarily longer than using no positioning aid at all.Conclusion:The presented fixation system allows reliable, flexible and efficient patient positioning for extracranial stereotactic radiotherapy.Hintergrund und Ziel:Voraussetzung für eine konformale fraktionierte Strahlentherapie ist eine präzise reproduzierbare Positionierung des Patienten und des Zielvolumens. Vorgestellt wird ein auf dem Doppelvakuumprinzip basierendes Fixationssystem, das sowohl für konventionelle als auch extrakranielle stereotaktische Bestrahlungen eingesetzt werden kann.Material und Methodik:Mittels einer Fixationsfolie, mit der er auch zusätzlich fixiert werden kann, wird der Patient vor der Abformung in die Vakuummatratze hineingepresst. Eine exakt auf einer indexierten Bodenplatte positionierbare Plexiglashaube dient als stereotaktischer Rahmen. Bei zehn Patienten mit Zielvolumina im Abdomen und Becken wurden vor jeder Bestrahlung orthogonale digitale Verifikationsaufnahmen angefertigt. Diese wurden mit den digital rekonstruierten Röntgenbildern (DRRs) des dreidimensionalen (3-D) Planungssystems verglichen. Aus den Abweichungen der drei Raumrichtungen wurden die 3-D-Vektoren als Maß für die Repositionierungsgenauigkeit errechnet.Ergebnisse:Der Mittelwert der für alle Patienten errechneten 3-D-Vektoren (187 Fraktionen) betrug 2,5 ± 1,1 mm. Der mit 10 mm größte 3-D-Vektor wurde bei einem in Bauchlage bestrahlten Patienten beobachtet. Die initiale Abformung dauerte im Durchschnitt 15 min (10–30 min). Der tägliche zeitliche Lagerungsaufwand am Bestrahlungsgerät ist nur unwesentlich länger als ohne Fixationshilfe.Schlussfolgerung:Das vorgestellte Fixierungssystem ermöglicht eine zuverlässige, flexible und effiziente Patientenpositionierung für die stereotaktische Bestrahlung extrakranieller Tumoren.

A Simple and Non-Invasive Vacuum Mouthpiece-Based Head Fixation System for High Precision Radiotherapy

Purpose: To demonstrate why conventional non-invasive mouthpiece-based fixation has not achieved the expected accuracy and to suggest a solution of the problem. Patients and Methods: The Vogele Bale Hohner (VBH) head holder is a non-invasive vacuum mouthpiece-based head fixation system. Feasibility and repositioning accuracy were evaluated by portal image analysis in 12 patients with cranial tumors intended for stereotactic procedures, fixated with the newest version (VBH HeadFix-ARC®). Results: Portal image analysis (8 patients evaluated in 2-D, 4 patients in 3-D) showed that even in routine external beam radiation therapy, treatment can be applied to within a mean 2-D and 3-D accuracy of under 2 mm (SD 0.92 mm and 1.2 mm, respectively) with cost and repositioning time per patient and patient comfort comparable to that of common thermoplastic masks. Conclusion: These preliminary results show that high repositioning accuracy does not rule out simple and quick application and patient comfort. Paramount, however, is tensionless repositioning via the vacuum mouthpiece.Ziel: Fixationssysteme, die auf konventionellen (nicht Vakuum-)Mundstücken basieren, erreichen oftmals nicht die erwartete Genauigkeit. Die vorliegende Arbeit beschäftigt sich mit den möglichen Ursachen und bietet entsprechende Lösungen. Patienten und Methoden: Der Vogele-Bale-Hohner-(VBH-)Head-Holder ist ein nicht invasives, auf einem Vakuummundstück (Abbildung 1) basierendes Kopffixationssystem (Abbildungen 2 und 3). Bei zwölf Patienten mit kraniellen Tumoren wurde mit der neuesten Version (VBH HeadFix-ARC®) die Repositionsgenauigkeit mittels Portal Imaging untersucht. Ergebnisse: Die Portal-Imaging-Auswertung (acht Patienten in 2-D, vier Patienten in 3-D) bestätigte, dass eine Bestrahlung im Kopfbereich auch in der klinischen Routine mit einer mittleren Genauigkeit von unter 2 mm (Standardabweichung 0,92 bzw. 1,2 mm) appliziert werden kann, während Kosten, Repositionsdauer und Akzeptanz der Patienten vergleichbar sind mit denen thermoplastischer Masken. Schlussfolgerung: Diese vorläufigen Ergebnisse zeigen, dass eine hohe Repositionierungsgenauigkeit ein einfaches, schnelles und für den Patienten angenehmes System nicht ausschließt. Ausschlaggebend ist die spannungsfreie Lagerung mittels Vakuummundstück.

Comparison of Inductively Coupled Plasma Atomic Emission Spectrometry and Inductively Coupled Plasma Mass Spectrometry With Quantitative Neutron Capture Radiography for the Determination of Boron in Biological Samples From Cancer Therapy

Comparison of inductively coupled plasma atomic emission spectrometry and inductively coupled plasma mass spectrometry with quantitative neutron capture radiography for the determination of boron in b

Erste Erfahrungen mit computerunterstützter stereotaktischer interstitieller Brachytherapie

PURPOSE To reach an optimal treatment result and to avoid damage to critical structures a homogeneous dose distribution in the tumor volume with a rapid decreasing dose to the surrounding structures is necessary. Fractionated interstitial brachytherapy of tumors in the ENT region employing needles depends on exact localization of the target volume during all fractions. Therefore reproducibility of positioning of the needle(s) plays an important role. MATERIAL AND METHODS We used the ISG Viewing Wand system in combination with the Vogele-Bale-Hohner (VBH) head holder and a new targeting device. Point of entrance, pathway, and target point of the needle were planned and insertion of the needle simulated in advance. To date we have treated 7 patients with inoperable tumors in the ENT region. The actual position of the needle in the control CT was compared to the planned position. RESULTS The accuracy of positioning of the needle depended on the location of the tumor. In a patient with a recurrent retroorbital adenocarcinoma the mean accuracy was 1 mm. Due to soft tissue displacement in the neck region and the resulting necessity to readjust the targeting device the needle was placed with a mean deviation of 15 mm between the planned and the actual position. CONCLUSIONS Computer-assisted frameless stereotactic interstitial brachytherapy allows for precise, reproducible and preplanned insertion of hollow needles into target structures closely adherent to the surrounding tissue, thus avoiding damage of neighbouring structures. This technique is of great advantage in treating deeply seated tumors which are fixed to bony structures, especially at the skull base. Inaccuracy in the neck region caused by soft tissue shift requires improvement of the immobilization in this region.ZusammenfassungFragestellungDie fraktionierte interstitielle Brachytherapie mit Nadeln von Tumoren im HNO-Bereich erfordert eine exakte Lokalisierung des Zielgewebes bei allen Bestrahlungsfraktionen. Eine wichtige Voraussetzung hier für ist die Reproduzierbarkeit der Positionierung der Nadel(n).Material und MethodenZur Ansteuerung verwendeten wir das ISG-Viewing-Wand-Navigationssystem (ISG Technologies Inc., Mississauga, Ontario, Kanada) in Kombination mit der Vogele-Bale-Hohner-(VBH-) Kopfhalterung (Fa. Wellhöfer Dosimetrie, Schwarzenbruck, Deutschland) und einer Zielvorrichtung. Eintrittspunkt, Stichlanal und Zielpunkt werden vor der Bestrahlungssitzung geplant, und das Vorschieben der Nadel wird simuliert. Wir haben diese Methode bei sieben Patienten mit inoperablen Kopf-Hals-Tumoren angewendet und jeweils die Nadellage am Kontroll-CT mit der geplanten Lokalisation verglichen.ErgebnisseDie Abweichung der erreichten von der geplanten Position der Nadel war von der Tumorlokalisation abhängig. Bei einem intraorbitalen, retrobulbären Tumorrezidiv eines Adenokarzinoms wurde eine mittlere Genauigkeit von 1 mm erzielt. Aufgrund der Weichteilverschieblichkeit und der Notwendigkeit der Nachjustierung der Zielvorrichtung war die Positionierung im Bereich des Halses nur mit einer mittleren Genauigkeit von 15 mm möglich.SchlußfolgerungenDie computerunterstützte, rahmenlos stereotaktische interstitielle Brachytherapie erlaubt die exakte, reproduzierbare und vorgeplante Plazierung von Brachytherapiehohlnadeln in wenig verschiebliche Zielstrukturen unter Schonung benachbarten Gewebes. Sie ist daher speziell bei der Therapie von am Knochen adhärenten, tiefliegenden Tumoren, insbesondere an der Schädelbasis, von Vorteil. Die durch Weichteilverschieblichkeit bedingte Ungenauigkeit in der Halsregion erfordert die Verbesserung der Immobilisation in dieser Region.AbstractPurposeTo reach an optimal treatment result and to avoid damage to critical structures a homogenous dose distribution in the tumor volume with a rapid decreasing dose to the surrounding structures is necessary. Fractionated interstitial brachytherapy of tumors in the ENT region employing needles depends on exact localization of the target volume during all fractions. Therefore reproducibility of positioning of the needle(s) plays an important role.Material and MethodsWe used the ISG Viewing Wand system in combination with the Vogele-Bale-Hohner (VBH) head holder and a new targeting device. Point of entrance, pathway, and target point of the needle were planned and insertion of the needle simulated in advance. To date we have treated 7 patients with inoperable tumors in the ENT region. The actual position of the needle in the control CT was compared to the planned position.ResultsThe accuracy of positioning of the needle depended on the location of the tumor. In a patient with a recurrent retroorbital adenocarcinoma the mean accuracy was 1 mm. Due to soft tissue displacement in the neck region and the resulting necessity to readjust the targeting device the needle was placed with a mean deviation of 15 mm between the planned and the actual position.ConclusionsComputer-assisted frameless stereotactic interstitial brachytherapy allows for precise, reproducible and preplanned insertion of hollow needles into target structures closely adherent to the surrounding tissue, thus avoiding damage of neighbouring structures. This technique is of great advantage in treating deeply seated tumors which are fixed to bony structures, especially at the skull base. Inaccuracy in the neck region caused by soft tissue shift requires improvement of the immobilization in this region.

Light ion facility projects in Europe: methodological aspects for the calculation of the treatment cost per protocol.

In the framework of the European Network for Research in Light Ion Hadron Therapy (ENLIGHT), the health economics group develops a methodology for assessing important investment and operating costs of this innovative treatment against its expected benefits. The main task is to estimate the cost per treated patient. The cost analysis is restricted to the therapeutic phase from the hospital point of view. An original methodology for cost assessment per treatment protocol is developed based on standard costs. Costs related to direct medical activity are based on the production process analysis, whereas indirect and non direct medical costs are allocated to each protocol using relevant cost-drivers. The resulting cost model will take into account the specificities of each therapeutic protocol as well as the particularities of each of the European projects.

A challenge for high-precision radiation therapy: The case for hadrons

SummaryThe sophistication of Hadron facilities led to major technical and conceptual advances in the treatment immobilization, reproducability, planning and execution. Some of these developments have had a pivotal impact on conventional treatments, which can now approach the dose localization advantage of protons in the majority of clinical situations. While the biological advantages of neutrons may finally be combined with excellent dose localization in Heavy Ion Facilities, modern surgical or systemic treatment methods may reduce high LET advantages. Clinical trials still need to define the relative merits of these approaches in their most modern implentation. The advantage gap has certainly been narrowed by recent developments in conventional therapy.

Oxygen tension in transplanted mouse osteosarcomas during fractionated high-LET-and Low-LET radiotherapy — Predictive aspects for choosing beam quality?

PurposeThe lower OER of high-LET radiations, compared to conventional (low-LET) radiations, has often been put forward as an argument for using high-LET radiotherapy in the management of hypoxic tumours. Among the different neutron beams used in therapy, the reactor fission neutrons have the lowest OER. The aim of the present study is to follow the variations of tumour oxygenation status during fractionated irradiation with different radiation qualities. Little information is available so far after fractionated high-LET irradiation. In addition, the RBE of reactor fission neutrons for effects on tumours and on normal tissues are compared.Material and MethodsMurine OTS 64-osteosarcomas were transplanted in 102 balb-C mice and irradiated by 36 Gy of photons in fractions of 3 Gy five times a week (group P-36/3) or by 12 Gy of reactor fission neutrons in fractions of 2 Gy two times a week (group N-12/2). Irradiations started at a tumor volume of 500 to 600 mm3. A third group received no radiotherapy, but all investigations (group CG). Tumor volume and tumor oxygenation were measured once a week under therapy and during three weeks after therapy. For in vivo-evaluation of oxygen status a computerized polarographic needle electrode system (KIMOC pO2 histograph, Eppendorf) was used. The median pO2 and the hypoxic fraction (pO2 values <5 mm Hg) of single tumors and of total groups were calculated from pooled histograms and from row data as well.ResultsIn correlation with the increase of tumor volume, from day 1 to day 42 of follow-up the median pO2 decreased from 20 mm to 8 mm Hg and the hypoxic fraction increased from 7% to 31%. After fractionated photon therapy a growth delay of three weeks was observed. Six weeks after beginning of the irradiation the median tumor volume had been doubled again. After fission neutron therapy growth delay continued until the end of the follow-up period. In both of the irradiated groups a significant decrease of median pO2 values and an increase of the hypoxic fraction were observed under radiotherapy. Hypoxia was more intensive after neutrons with a decrease of the median pO2 from 20 mm Hg to 1 mm Hg vs. 10 mm Hg after photon therapy and with an increase of the hypoxic fraction from 7% to 78% vs. 36% respectively. Two weeks after the end of therapy the median pO2 and the hypoxic fraction of both treated groups reached the levels prior to irradiation indicating a complete reoxygenation.ConclusionDuring fractionated irradiation of murine osteosarcomas weith photons and reactor fission neutrons, a marked hypoxia was observed for both radiation qualities, but hypoxia was more intense during fractionated neutron irradiation. After irradiation, a complete reoxygenation occured in both groups independently of the degree of hypoxia observed during the treatment. The RBE of reactor fission neutrons, after fractionated irradiation, was much higher for effects on murine osteosarcomas compared to their RBE observed for normal tissues in previous experiments. Present data are in agreement with our clinical observations on more than 300 patients treated with reactor fission neutrons for advanced and hypoxic tumours with various histologies.

Computer-Assisted Interstitial Brachytherapy

We present the current state-of-the art of computer-assisted interstitial (fractionated) brachytherapy as a “picture-book” without wanting to give an in-depth presentation of either brachytherapy itself or of otolaryngologic aspects of oncologic treatment. However, our results show that 3D-computer-assisled navigation techniques can successfully be applied in interstitial brachytherapy to exactly plan the hollow-needle’s position(s) in order to reach a prospective planning of brachytherapy which exploits the full 3D-information of the modern imagery and incorporates state-of-the-art navigational techniques.