Lorenz Schlenger

IMPACT OF THE FILLING STATUS OF THE BLADDER AND RECTUM ON THEIR INTEGRAL DOSE DISTRIBUTION AND THE MOVEMENT OF THE UTERUS IN THE TREATMENT PLANNING OF GYNAECOLOGICAL CANCER

PURPOSE Determination of the impact of the filling status of the organs at risk (bladder and rectum) on the uterus mobility and on their integral dose distribution in radiotherapy of gynaecological cancer. METHODS In 29 women suffering from cervical or endometrial cancer two CT scans were carried out for treatment planning, one with an empty bladder and rectum, the second one with bladder and rectum filled. The volumes of the organs at risk were calculated and in 14 patients, receiving a definitive radiotherapy, the position of the uterus within the pelvis was shown using multiplanar reconstructions. After generation of a 3D treatment plan the dose volume histograms were compared for empty and filled organs at risk. RESULTS The mobility for the corpus uteri with/without bladder and rectum filling was in median 7 mm (95%-confidence interval: 3-15 mm) in cranial/caudal direction and 4 mm (0-9 mm) in posterior/anterior direction. Likewise, cervical mobility was observed to be 4 mm (-1-6 mm) mm in cranial/caudal direction. A full bladder led to a mean reduction in organ dose in median from 94-87% calculated for 50% of the bladder volume (P < 0.05, Wilcoxons matched-pairs signed-ranks test). For 66% of the bladder volume the dose could be reduced in median from 78 to 61% (P < 0.005) and for the whole bladder from 42 to 39% (P < 0.005), respectively. No significant contribution of the filling status of the rectum to its integral dose burden was noticed. CONCLUSIONS Due to the mobility of the uterus increased margins between CTV and PTV superiorly, inferiorly, anteriorly and posteriorly of 15, 6 and 9 mm each, respectively, should be used. A full bladder is the prerequisite for an integral dose reduction.

Image guided respiratory gated hypofractionated Stereotactic Body Radiation Therapy (H-SBRT) for liver and lung tumors: Initial experience

To evaluate our initial experience with image guided respiratory gated H-SBRT for liver and lung tumors. The system combines a stereoscopic x-ray imaging system (ExacTrac® X-Ray 6D) with a dedicated conformal stereotactic radiosurgery and radiotherapy linear accelerator (Novalis) and ExacTrac® Adaptive Gating for dynamic adaptive treatment. Moving targets are located and tracked by x-ray imaging of implanted fiducial markers defined in the treatment planning computed tomography (CT). The marker position is compared with the position in verification stereoscopic x-ray images, using fully automated marker detection software. The required shift for a correct, gated set-up is calculated and automatically applied. We present our acceptance testing and initial experience in patients with liver and lung tumors. For treatment planning CT and Fluorodeoxyglucose-Positron Emission Tomography (FDG-PET) as well as magnetic resonance imaging (MRI) taken at free breathing and expiration breath hold with internal and external fiducials present were used. Patients were treated with 8–11 consecutive fractions to a dose of 74.8–79.2 Gy. Phantom tests demonstrated targeting accuracy with a moving target to within ±1 mm. Inter- and intrafractional patient set-up displacements, as corrected by the gated set-up and not detectable by a conventional set-up, were up to 30 mm. Verification imaging to determine target location during treatment showed an average marker position deviation from the expected position of up to 4 mm on real patients. This initial evaluation shows the accuracy of the system and feasibility of image guided real-time respiratory gated H-SBRT for liver and lung tumors.

Novalis frameless image-guided noninvasive radiosurgery: initial experience.

OBJECTIVETo evaluate our initial experience with Novalis (BrainLAB, Heimstetten, Germany) frameless image-guided noninvasive radiosurgery. METHODSThe system combines the dedicated Novalis linear accelerator with ExacTrac X-Ray 6D, an infrared camera and a kilovolt stereoscopic x-ray imaging system, a noninvasive mask system, and ExacTrac robotics for patient positioning in six degrees of freedom. Reference cranial skeletal structures are radiographically imaged and automatically fused to digital reconstructed radiographs calculated from the treatment planning computed tomographic scan to find the target position and accomplish automatic real-time tracking before and during radiosurgery. We present the acceptance testing and initial experience in 15 patients with 19 intracranial lesions treated between December 2005 and June 2006 at the Charité by frameless image-guided radiosurgery with doses between 12 and 20 Gy prescribed to the target-encompassing isodose. RESULTSPhantom tests showed an overall system accuracy of 1.04 ± 0.47 mm, with an average in-plane deviation of 0.02 ± 0.96 mm for the x-axis and 0.02 ± 0.70 mm for the y-axis. After infrared-guided patient setup of all patients, the overall average translational deviation determined by stereoscopic x-ray verification was 1.5 ± 1.3 mm, and the overall average rotational deviation was 1.0 ± 0.8 degree. The data used for radiosurgery, after stereoscopic x-ray verification and correction, demonstrated an overall average setup error of 0.31 ± 0.26 mm for translation and 0.26 ± 0.23 degree for rotation. CONCLUSIONThis initial evaluation demonstrates the system accuracy and feasibility of Novalis image-guided noninvasive radiosurgery for intracranial benign and malignant lesions.

Palliative Strahlentherapie von KnochenmetastasenEine retrospektive Analyse von 176 Patienten

Ziel: Die Effizienz der palliativen Strahlentherapie bei ossärer Metastasierung wird in dieser retrospektiven Studie untersucht. Das Spektrum der den Knochenmetastasen zugrundeliegenden unterschiedlichen Primärtumoren und Lokalisationen wird analysiert. Zusätzlich werden die in dieser retrospektiven Studie eingesetzten Fraktionierungsschemata im Hinblick auf die Palliation (Schmerzremission) analysiert. Dabei soll zwischen globaler Ansprechrate und partieller sowie kompletter Schmerzremission differenziert werden. Patienten und Methode: Diese retrospektive quantitative Analyse umfaßt 176 Patienten, bei denen im Zeitraum von April 1992 bis November 1993 258 Lokalisationen mit Knochenmetastasen bestrahlt wurden. Der prozentuale Anteil ossärer Metastasen im Verhältnis zur Gesamtpatientenzahl, die zugrundeliegenden Primärtumoren, Lokalisationen und unterschiedlichen Fraktionierungsregime wurden quantifiziert. Bei den häufigsten Fraktionierungsregimen und Tumorentitäten wurde die Palliation (Schmerzremission) als globale Ansprechrate und differenziert in Form der partiellen bzw. kompletten Schmerzremission analysiert. Ergebnisse: Knochenmetastasen machten 8% aller bestrahlten Lokalisationen in der Strahlenklinik der Charité innerhalb des 19monatigen Beobachtungszeitraums aus. Es wurden insgesamt 21 unterschiedliche Tumorentitäten bestrahlt. Ossäre Metastasen traten am häufigsten beim Mammakarzinom (49%), Bronchialkarzinom (15%) und Nierenzellkarzinom (6%) auf. Der Prädilektionsort der ossären Metastasen war die Wirbelsäule in 52%. Von den 19 unterschiedlichen Fraktionierungsregimen wurden am häufigsten die folgenden eingesetzt: 4mal 5 Gy (32%), 10mal 3 Gy (18%), 6mal 5 Gy (9%), 7mal 3 Gy (7%), 10mal 2 Gy (5%) und 2mal 8 Gy. Die globalen Ansprechraten betrugen dementsprechend: 72%, 79%, 74%, 76%, 75% und 72%, die kompletten Remissionen: 35%, 32%, 30%, 35%, 33% und 33%. Ein Unterschied zwischen den häufigsten Tumorentitäten sowie den verschiedenen Lokalisationen und der Palliation konnte weder in den globalen Ansprechraten noch in den differenzierteren Endpunkten der partiellen bzw. kompletten Schmerzremissionen quantifiziert werden. Schlußfolgerung: Die verschiedenen Fraktionierungsregime unterscheiden sich nicht signifikant hinsichtlich ihrer Effizienz bei ossären Metastasen. Die Palliation ist in ca. 75% aller Fälle gewährleistet mit einer Rate von 33% kompletten und 42% partiellen Schmerzremissionen. Unter alleiniger Berücksichtigung der Schmerzreduktion rechtfertigen diese Resultate nicht die Empfehlung einer Standardfraktionierung. Aus klinisch pragmatischen Gründen sollten gängige Fraktionierungsschemata wie 10mal 3 Gy über zwei Wochen oder 5mal 4 Gy in einer Woche eingesetzt werden. Neben der Palliation sollte jedoch auch – insbesondere bei Patienten mit längerer Prognose – die Remineralisation als Voraussetzung der Stabilisierung und Frakturprävention und als der einzige objektivierbare Parameter des Strahlentherapieerfolgs in zukünftige prospektive Analysen einfließen.Background: The effect of the palliative irradiation of bone metastases was explored in this retrospective analysis. The spectrum of primary tumor sites, the localization of the bone metastases and the fractionation schedules were analyzed with regard to palliation discriminating total, partial and complete pain response. Patients and Methods: One hundred seventy-six patients are included in this retrospective quantitative study from April 1992 to November 1993. Two hundred fifty-eight localizations of painful bone metastases were irradiated. The percentage of bone metastases of the total irradiated localizations in our department of radiotherapy in the Charité-Hospital, the primary tumor sites, the localizations and the different fractionation schedules were explored. The total, partial and complete pain response was analyzed in the most often used fractionation schedules and by primary tumor sites. Results: Eight per cent of all irradiated localizations in the observation period were bone metastases. There were irradiated bone metastases of 21 different tumor sites. Most of the primary tumor sites were breast cancer (49%), lung cancer (6%) and kidney cancer (16%). The most frequent site of metastases was the vertebral column (52%). The most often used fractination schedules were: 4 × 5 Gy (32%), 10 × 3 Gy (18%), 6 × 5 Gy (9%&), 7 × 3 Gy (7%), 10 × 2 Gy (5%) and 2 × 8 Gy. The total response rates in this fractionation schedules were 72%, 79%, 74%, 76%, 75% and 72%, the complete response rates were 35%, 32%, 30%, 35%, 33% and 33%. There were no significant differences between the most often irradiated primary tumor sites, the most frequent localizations and the palliation with regard to total, partial and complete pain response. Conclusion: There are no differences between the different fractionation schedules with regard to the pain effect of bone metastases. A palliation is ensured in 75% of all cases with a partial response of 42% and complete response of 33%. With regard to pain response these results do not justify a recommendation for a standard fractionation schedule. Current fractionation schedules such as 10 × 3 Gy for 2 weeks or 5 × 4 Gy for 1 week should be used. Another point is the recalcification in the palliative treatment of bone metastases in patients with better prognosis. The recalcification is the basis for stabilization and prevention of fractures. This aspect should be explored in prospective studies.

Virtual simulation in patients with breast cancer

BACKGROUND Investigation of the feasibility and effectiveness of virtual simulation in patients receiving radiotherapy of the breast. METHODS Twenty-three patients were included in the study. All of them underwent a course of postoperative tangential breast irradiation. The patients were prospectively randomised into two groups. Group A patients (n=11) received a conventional computed tomography -based treatment planning, group B patients (n=12) a virtual simulation. The results of both treatment planning procedures were compared. RESULTS The treatment planning was feasible in all patients. The time expenditure could be reduced from a median of 45.0 to 16.5 min and from 55.0 to 32.0 min for the technician and physician, respectively, using virtual simulation. Furthermore the treatment planning for the patient could be reduced from a median of 45.0 min in two sessions to 16.5 min in one session. The image quality of the digital reconstructed radiographs was satisfying compared to the simulation films. The incidence and extension of set-up corrections for the patients at the first treatment were comparable in both groups. The time interval between the planning CT and the first treatment could be reduced by 31% using virtual simulation due to the omission of the conventional simulation. CONCLUSION The virtual simulation is a feasible tool for the treatment planning of patients undergoing tangential irradiation of the breast. Compared with the conventional simulation procedure virtual simulation is superior regarding to the precision of patients marking, the quality of the reference images and, the time expenditure for the patients and medical staff.

Combined SPECT/CT imaging using 123I-IMT in the detection of recurrent or persistent head and neck cancer

The aim of the study was to assess the clinical value of combined SPECT/CT imaging using L-3-[123I]iodine-α-methyl tyrosine (IMT) for the differential diagnosis of recurrences in patients pre-treated for head and neck cancer. Thirty-four consecutive patients with biopsy-proven carcinomas, who had previously been treated by surgery and/or radio/chemotherapy, were examined at our clinic by IMT-SPECT using a dual-head system with integrated low-dose CT. SPECT results were correlated with histopathology, clinical and CT/MRI follow-up data. In the follow-up after SPECT examination, the final diagnosis of recurrent tumour was established in 26 patients; the remaining eight patients were recurrence-free (follow-up >6 months). IMT-SPECT/CT correctly detected recurrent disease and/or neck lymph node metastases in 22 patients. In addition, distant metastases were displayed in two patients. The study was false-negative in four patients (sensitivity 85%). True-negative results were registered in seven patients, and false-positive in one patient. Image fusion with coregistered low-dose CT facilitates the localisation and interpretation of IMT-SPECT findings. IMT-SPECT using integrated low-dose CT is a promising non-invasive imaging tool for the detection of head and neck cancer recurrences and their differentiation from treatment-induced changes.

Diagnostic Value of 123I-IMT SPECT in the Follow-up of Head and Neck Cancer

Background: Nuclear medicine imaging is increasingly used in the evaluation of tumors of the head and neck. In the current study, we assess the value of single-photon emission tomography (SPECT) using the amino acid tracer L-3-[123I]iodine-a-methyl-tyrosine (IMT) for the detection of recurrent head and neck cancer. Patients and Methods: 45 consecutive patients with suspected recurrence of previously treated head and neck cancer were examined by IMT-SPECT using a dual head system with integrated low-dose computed tomography (CT). The accuracy of the IMT-SPECT was evaluated by correlating the findings with results of histology or clinical and CT/MRI (magnetic resonance imaging) follow-up examinations. Results: The sensitivity, specificity and accuracy of IMT-SPECT in the detection of recurrent/persistent tumors were 83, 89 and 84.5%, respectively. The positive and negative predictive value amounted to 96.5 and 60%, respectively. Conclusion: IMT-SPECT using integrated low-dose CT appears to be a helpful complementary imaging tool for the detection of local recurrences and lymph node metastases of head and neck cancer and their differentiation from treatment-induced changes. The advantage of the method is the high positive predictive value in the diagnosis of relapsed tumors. However, a negative IMT-SPECT result does not exclude a recurrence.

Virtuelle Simulation@@@Virtual simulation — First clinical results in patients with prostate cancer: Erste klinische Ergebnisse bei Patienten mit Prostatakarzinom

AIM Investigation of options of virtual simulation in patients with localized prostate cancer. PATIENTS AND METHODS Twenty-four patients suffering from prostate cancer were virtual simulated. The clinical target volume was contoured and the planning target volume was defined after CT scan. The isocenter of the planning target volume was determined and marked at patients skin. The precision of patients marking was controlled with conventional simulation after physical radiation treatment planning. RESULTS Mean differences of the patients mark revealed between the 2 simulations in all room axes around 1 mm. The organs at risk were visualized in the digital reconstructed radiographs. CONCLUSIONS The precise patients mark of the isocentre by virtual simulation allows to skip the conventional simulation. The visualisation of organs at risk leeds to an unnecessarily of an application of contrast medium and to a further relieve of the patient. The personal requirement is not higher in virtual simulation than in conventional CT based radiation treatment planning.ZusammenfassungZielUntersuchung von Optionen der virtuellen Simulation bei Patienten mit lokal begrenztem Prostatakarzinom.Patienten und Methode24 Patienten mit einem lokal begrenzten Prostatakarzinom wurden virtuell simuliert. Nach dem Bestrahlungsplanungs-CT erfolgte die Konturierung des Klinischen Zielvolumens und des Planungszielvolumens sowie die Bestimmung des geometrischen Isozentrums, das auf der Haut markiert wurde. Nach Erstellung des Bestrahlungsplanes wurde die Genauigkeit der Markierung des Isozentrums am konventionellen Simulator überprüft.ErgebnisseDie Markierung des Isozentrums an den Patienten erfolgte mit einer mittleren Abweichung von 1 mm in allen drei Ebenen. Auf den digital rekonstruierten Simulationsaufnahmen werden alle vorher konturierten Strukturen wie Zielvolumina und Risikoorgane dargestellt.SchlußfolgerungenAufgrund der Präzision der Markierung des Isozentrums kann bei Einsatz der virtuellen Simulation bei Patienten mit einem lokal begrenzten Prostatakarzinom auf die konventionelle Simulation verzichtet werden. Die Darstellung der Risikoorgane in den digital rekonstruierten Simulationsaufnahmen ermöglicht den Verzicht auf die Kontrastmittelapplikation bei der Simulation und führt zu einer weiteren Entlastung für den Patienten. Der personelle Aufwand ist im Vergleich zur konventionellen CT-gestützten Bestrahlungsplanung nicht höher.AbstractAimInvestigation of options of virtual simulation in patients with localized prostate cancer.Patients and MethodsTwenty-four patients suffering from prostate cancer were virtual simulated. The clinical target volume was contoured and the planning target volume was defined after CT scan. The isocenter of the planning target volume was determined and marked at patient’s skin. The precision of patients marking was controlled with conventional simulation after physical radiation treatment planning.ResultsMean differences of the patient’s mark revealed between the 2 simulations in all room axes around 1 mm. The organs at risk were visualized in the digital reconstructed radiographs.ConclusionThe precise patient’s mark of the isocentre by virtual simulation allows to skip the conventional simulation. The visualisation of organs at risk leeds to an unnecessarity of an application of contrast medium and to a further relieve of the patient. The personal requirement is not higher in virtual simulation than in conventional CT based radiation treatment planning.

Assessment of Treatment Techniques and Collimation in Conformal Stereotactic Radiosurgery and Radiotherapy

In radiation oncology more and more effort is taken to include the dose conformity to the target as well as the dose sparing of risk organs (OAR) and healthy tissue to the treatment planing. Conformal stereotactic radiosurgery and radiotherapy (CSRS and CSRT) offer the potential to optimise these parameters according to the demands of the physician and the physicist. The study compares treatment plans using different techniques for dose delivery as static beams, arcs or multiple isocentres. Also different beam shaping devices for CSRS and CSRT as conformal blocks, circular cones or multileaf collimators have been considered.