Students' learning behavior in digital education for radiation oncology.

PURPOSE: Digitalization of medical education is an important trend in terms of reforming and modernizing the global education environment. It has been long requested by students and politicians. The goal of this study was to assess the student perception of a newly developed digital educational program in radiation oncology (RO) using an interactive e­book combined with short learnings clips on a YouTube channel combined with periodic videoconferences and a forum for queries. METHODS: We performed five evaluations during and at the end of two terms with multiple-choice and free-text answers. We evaluated student perception of our new digital learning scenario in three semesters: one pre-clinical and two clinical semesters. In addition, we analyzed all comments from the kMED forum, the YouTube channel, or the e­mail contacts. We analyzed the learning behavior of the students based on access to the videos and the number and quality of the reflective questions answered as well as the results of the final examinations. RESULTS: The students accepted the offer for asynchronous teaching and mainly learned on weekdays (74% of the videos), but also on weekends (23%) and less on public holidays (4%). The answer quality of the reflective questions was good with over 50% correct answers on the first attempt. Learning to be on one's own authority was very difficult for the students, even in the last clinical semesters of the medical study. Without direct intervention by the teacher, access to the learning material by the students was limited and delayed. Therefore, voluntary interim tests were performed during the first analysis term, which led to an increased number of student accesses to the videos and higher number of answers. Nevertheless, in the first analysis term, the average results in the final exam of the students who did not perform the interim test were below average at 59.1%, and the students who performed the test had better results at 69.5% but this was also not satisfactory. In the second analysis term, we taught with the same digital teaching model but with an additional scheme for learning over the term, 2­week compulsory intermediate tests, and frequent videoconferences to answer any questions. In this term, we measured a success rate of 93% in the final exam. All annotations were very positive regarding the new educational project. The evaluations showed high acceptance of the new education program. The students stated they would prefer the new education course to be continued in future. CONCLUSION: Digital teaching methods make not only the type and quality of teaching transparent, but also the learning behavior of the students. Our analysis has shown that, in addition to the quality of the teaching, the clear structure and specification of the learning content per learning week as well as regular monitoring of what has been learned are of decisive importance for the learning success of the students.

Palliative care in everyday practice of radiation oncologists : Results from a web-based survey among medical members of the German Society for Radiation Oncology (DEGRO).

PURPOSE: Little is known about the attitudes of radiation oncologists towards palliative care, about their competences in this field, and about the collaboration with palliative care specialists. Our aim was to close this gap and understand more about the importance of an additional qualification in palliative care. METHODS: Medical members of the German Society for Radiation Oncology (DEGRO) were electronically surveyed during November-December 2016. RESULTS: The survey was emailed successfully to 1110 addressees, whereas a total of 205 questionnaires were eligible for analysis (response rate 18.4%). 55 (26.8%) of the respondents had an additional qualification in palliative care. Physicians who had an additional qualification in palliative care (PC qualification) reported palliative care needs for their patients more frequently than the other respondents (89.0 vs. 82.7%, p = 0.008). Furthermore, they were most likely to report a high confidence in palliative care competences, such as "communication skills & support for relatives" (83.6 vs. 59.3%, p = 0.013), "symptom control," and "pain management" (94.5 vs. 67.7%, p < 0.001 and 90.9 vs. 73.3%, p = 0.008, respectively). Respondents with a PC qualification more often involved palliative care specialists than the other respondents (63.3 vs. 39.3%, p = 0.007). Perceived main barriers regarding palliative care in radiation oncology included time aspects (9.2%), stigmata (8.5%), and the lack of interdisciplinary collaboration (8.5%). CONCLUSIONS: This analysis demonstrated that aspects of palliative care strongly impact on daily practice in radiation oncology. Additional qualifications and comprehensive training in palliative medicine may contribute to improved patient care in radiation oncology.

Changes in pulmonary function and influencing factors after high-dose intrathoracic radio(chemo)therapy.

PURPOSE: Using prospectively collected patient-related, dose-related, and pulmonary function test (PFT) data before radiotherapy (RT) and at several follow-up visits after RT, the time course of PFT changes after high-dose radio(chemo)therapy and influencing factors were analyzed. MATERIALS AND METHODS: From April 2012 to October 2015, 81 patients with non-small-cell lung carcinoma (NSCLC), small cell lung carcinoma (SCLC), or esophageal carcinoma where treated with high-dose radio(chemo)therapy. PFT data were collected before treatment and 6 weeks, 12 weeks, and 6 months after RT. The influence of patient- and treatment-related factors on PFT was analyzed. RESULTS: Mean forced expiratory volume in 1 s (FEV1) constantly declined during follow-up (p = 0.001). In total, 68% of patients had a reduced FEV1 at 6 months. Mean vital capacity (VC) didn't change during follow-up (p > 0.05). Mean total lung capacity (TLC) showed a constant decline after RT (p = 0.026). At 6 months, 60% of patients showed a decline in VC and 73% in TLC. The mean diffusion capacity for carbon monoxide (DLCO) declined at 6 and 12 weeks, but recovered slightly at 6 months (p < 0.0005). At 6 months, 86% of patients had a reduced DLCO. After treatment, the partial pressure of CO2 in the blood (pCO2) was increased and pO2 was decreased (p > 0.05). Only the pretreatment PFT classification had a significant influence on the post-RT FEV1. CONCLUSION: DLCO seems to be the most reliable indicator for lung tissue damage after thoracic RT. Ventilation parameters appear to be less reliable. Concerning patient- or treatment-related factors, no reliable conclusion can be drawn regarding which factors may be relevant.

Patient's quality of life after high-dose radiation therapy for thoracic carcinomas : Changes over time and influence on clinical outcome.

PURPOSE: Quality of life (QoL) is an important factor in patient care. This analysis is focused on QoL before and after radio(chemo)therapy in patients with thoracic carcinomas, as well as on its influence on clinical follow-up and survival, and the correlation with treatment-related toxicities. MATERIALS AND METHODS: The analysis included 81 patients with intrathoracic carcinoma receiving radio(chemo)therapy. For analysis of QoL, the European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire (EORTC QLQ-C30) and the lung cancer-specific supplement (EORTC QLQ-LC13) were used. QoL data were collected before radiation treatment (RT), and 6 weeks, 12 weeks, 6 months, and 12 months after RT. Other factors were additionally analyzed, including clinical outcome, survival, and side effects. RESULTS: The functional scales showed maximum values or at least a recovery 12 weeks after RT. Symptoms with a high mean symptom score (> 40) at all appointments were fatigue, dyspnea, and coughing. Insomnia, peripheral neuropathy, appetite loss, dyspnea (from QLQ-LC13), and all pain parameters had an intermediate mean score (10-40). There were low mean scores of < 10 for nausea and vomiting, diarrhea, sore mouth, and hemoptysis. There was a significant correlation between clinical dysphagia and radiation pneumonitis with the associated symptom scales. None of the QoL scores had a significant influence on local and distant control or survival. CONCLUSION: 12 weeks after RT the QLQ-C30 functional scales show the highest scores or at least a temporary recovery. The symptom scales accurately reflect the common symptoms and treatment-related toxicities. QoL did not prove to be a significant predictor for local and distant control or survival.

Induced luminescence in water and PMMA - spectral analysis for irradiations with proton beams within the clinical energy range.

It was recently discovered that water and PMMA emit a weak luminescence signal when irradiated with protons within the clinically used energy range. This could offer a fast approach for range measurements in water. However, a complete explanation or investigation on the origin of the signal has not been published. In this work, a setup for the high-resolution spectral measurement of the weak luminescence signal in water and PMMA was designed. The measurement environment in the vicinity of a proton accelerator represented a major challenge for the sensitive optical measurements due to the presence of ionizing scattered radiation. A high-sensitive spectrometer in combination with a custom-made fiber was used to build a foundation for further analysis of the luminescence signal by providing accurate spectral information. For water, a broad distribution in the range from 240 to 900 nm with a maximum at 480 nm was obtained. A comparison of the spectra with previously published work indicates that the signal originates from excited states produced during the radiolysis of water. In comparison, differences between the water and the PMMA spectrum were observed. When examining the signal in PMMA, spectral differences were found compared to the measurements in water. The signal in PMMA was approximately 10 times stronger, had a narrower distribution and was shifted to lower wavelengths. Nevertheless, for the investigated proton energies, no spectral energy dependence was detected. In addition to the results for water and PMMA, a further luminescence signal was measured when the silica fiber used was directly irradiated with primary protons. All spectra, obtained in this work, describe the signal of proton-induced luminescence in water and PMMA with a high resolution of 3.4 nm and thus form a basis for further research, which could be a powerful tool in proton range verification.

Experimental determination of modulation power of lung tissue for particle therapy.

In particle therapy of lung tumors, modulating effects on the particle beam may occur due to the microscopic structure of the lung tissue. These effects are caused by the heterogeneous nature of the lung tissue and cannot be completely taken into account during treatment planning, because these micro structures are too small to be fully resolved in the planning CT. In several publications, a new material parameter called modulation power (Pmod) was introduced to characterize the effect. For various artificial lung surrogates, this parameter was measured and published by other groups and ranges up to approximately 1000µm. Studies investigating the influence of the modulation power on the dose distribution during irradiation are using this parameter in the rang of 100-800µm. More precise measurements forPmodon real lung tissue have not yet been published. In this work, the modulation power of real lung tissue was measured using porcine lungs in order to produce more reliable data ofPmodfor real lung tissue. For this purpose,ex-vivoporcine lungs were frozen in a ventilated state and measurements in a carbon ion-beam were performed. Due to the way the lungs were prepared and transferred to a solid state, the lung structures that modulate the beam could also be examined in detail using micro CT imaging. An optimization of the established methods of measuring the modulation power, which takes better account of the typical structures within lung tissue, was developed as well.

Estimating the modulating effect of lung tissue in particle therapy using a clinical CT voxel histogram analysis.

To treat lung tumours with particle therapy, different additional tasks and challenges in treatment planning and application have to be addressed thoroughly. One of these tasks is the quantification and consideration of the Bragg peak (BP) degradation due to lung tissue: as lung is an heterogeneous tissue, the BP is broadened when particles traverse the microscopic alveoli. These are not fully resolved in clinical CT images and thus, the effect is not considered in the dose calculation. In this work, a correlation between the CT histograms of heterogeneous material and the impact on the BP curve is presented. Different inorganic materials were scanned with a conventional CT scanner and additionally, the BP degradation was measured in a proton beam and was then quantified. A model is proposed that allows an estimation of the modulation power by performing a histogram analysis on the CT scan. To validate the model for organic samples, a second measurement series was performed with frozen porcine lunge samples. This allows to investigate the possible limits of the proposed model in a set-up closer to clinical conditions. For lung substitutes, the agreement between model and measurement is within ±0.05 mm and for the organic lung samples, within ±0.15 mm. This work presents a novel, simple and efficient method to estimate if and how much a material or a distinct region (within the lung) is degrading the BP on the basis of a common clinical CT image. Up until now, only a direct in-beam measurement of the region or material of interest could answer this question.

Optical range determination of clinical proton beams in water. A comparison with standard measurement methods.

As recently discovered, water emits a weak luminescence when it is irradiated with protons even with energies below the Cerenkov light threshold. In this work it was investigated if this phenomenon could be exploited for range measurements in proton therapy. A measurement setup based on a scientific CMOS camera that can be operated under normal room light was built and tested in a proof-of-principle experiment at the West German Proton Therapy Center, Essen. The luminescence depth profiles were analyzed to obtain the range information and the method was compared with ionization chamber based depth dose measurements. The noise caused by scattered radiation hitting the camera chip could be removed with a simple threshold-based median filter. The influence of Cerenkov radiation produced by delta electrons was analyzed by FLUKA simulations and it was shown that it does not affect the range measurements. It could be shown that the luminescence method is as fast as the multi-layer ionization chamber measurement (a few seconds) but with a higher depth resolution that is comparable with the Bragg peak chamber method. The proton ranges determined with the luminescence method agree with the reference methods better than 0.2% over the whole energy range 100-226MeV. The sensitivity of the method regarding detectable range shifts was tested. It was shown, that energy shifts of 0.5MeV (at 151MeV), leading to a range shift of ∼0.9mm, were clearly detectable.

Overestimation of low-dose radiation in intensity-modulated radiotherapy with sliding-window technique.

PURPOSE: To analyze different control-system limitations on the measured dose distributions in low-dose regions of simplified intensity fields with an electronic portal imaging device to ascertain the optimal settings for the control-system limitations in the planning system. MATERIAL AND METHODS: The authors created one field with an "optimal fluence" of intensity 1.0 (full dose) and one field with intensity 0.0 (no dose) in the central part of the field. The influence of different dose rates (DRs) and maximum leaf speeds (LS) on the calculated and measured dose and dose profiles were analyzed. RESULTS: Good agreement between calculated and measured dose in the case of a field of intensity 1.0 was found. For the field with intensity 0.0, the measured dose was 20-60% lower than the dose calculated by the "actual fluence". The results were found dependent on the DR and LS. CONCLUSION: The overestimation in regions of optimal intensity 0.0 by the planning system cannot be resolved by the user. Taking the measured dose in the region of desired intensity 1.0 and other technical limitations (like beam hold interrupts or spikes in the cross and longitudinal profiles) into consideration, the application of an LS of 2.5 cm/s and a DR of 500 MU/min is recommended in order to minimize radiation dose applied to organs at risk, which are located in regions of low intensity, like, for example, the spinal cord.

Gold markers for tumor localization and target volume delineation in radiotherapy for rectal cancer.

BACKGROUND AND PURPOSE: In locally advanced rectal cancer, neoadjuvant radiochemotherapy is indicated. To improve target volume definition for radiotherapy planning, the potential of implanted gold markers in the tumor region was evaluated. PATIENTS AND METHODS: In nine consecutive patients, two to three gold markers were implanted in the tumor region during rigid rectoscopy. Computed tomography scans were performed during treatment planning. All electronic portal imaging devices (EPIDs) recorded during treatment series were analyzed. All patients underwent complete tumor resection with meticulous histopathologic examination. RESULTS: The gold markers could easily be implanted into the mesorectal tissue at the caudal tumor border without any complications. They were helpful in identifying the inferior border of the planning target volume in order to spare normal tissue (in particular anal structures). No significant shift of the markers was found during the course of therapy. Marker matching of the EPIDs did not improve patient positioning in comparison to bone structure matching. The former position of at least one marker could be identified in all patients during histopathologic examination. CONCLUSION: The use of gold marker enables a more precise definition of the target volume for radiotherapy in patients with rectal cancer. This could eventually allow a better protection of anal structures of patients with a tumor localization > or = 5 cm cranial of the anal sphincter. The implantation of the gold markers improved communication between the surgeon, the radiooncologist and the pathologist resulting in intensified exchange of relevant informations.

Effect of irradiation on gene expression of rat liver adhesion molecules: in vivo and in vitro studies.

BACKGROUND AND PURPOSE: Migration of leukocytes into tissue is a key element of innate and adaptive immunity. An animal study showed that liver irradiation, in spite of induction of chemokine gene expression, does not lead to recruitment of leukocytes into the parenchyma. The aim of this study was to analyze gene expression of adhesion molecules, which mediate leukocyte recruitment into organs, in irradiated rat liver in vivo and rat hepatocytes in vitro. MATERIAL AND METHODS: Rat livers in vivo were irradiated selectively at 25 Gy. Isolated hepatocytes in vitro were irradiated at 8 Gy. RNA extracted within 48 h after irradiation in vivo and in vitro was analyzed by real-time PCR (polymerase chain reaction) and Northern blot. Adhesion molecule concentration in serum was measured by ELISA (enzyme-linked immunosorbent assay). Cryostat sections of livers were used for immunohistology. RESULTS: Significant radiation-induced increase of ICAM-1 (intercellular adhesion molecule-1), VCAM-1 (vascular cell adhesion molecule-1), JAM-1 (junctional adhesion molecule-1), beta1-integrin, beta2-integrin, E-cadherin, and P-selectin gene expression could be detected in vivo, while PECAM-1 (platelet-endothelial cell adhesion molecule-1) gene expression remained unchanged. In vitro, beta1-integrin, JAM-1, and ICAM-2 showed a radiation-induced increased expression, whereas the levels of P-selectin, ICAM-1, PECAM-1, VCAM-1, Madcam-1 (mucosal addressin cell adhesion molecule-1), beta2-integrin, and E-cadherin were downregulated. However, incubation of irradiated hepatocytes with either tumor necrosis factor-(TNF-)alpha, interleukin-(IL-)1beta, or IL-6 plus TNF-alpha led to an upregulation of P-selectin, ICAM-1 and VCAM-1. CONCLUSION: The findings suggest that liver irradiation modulates gene expression of the main adhesion molecules in vivo and in cytokine-activated hepatocytes, with the exception of PECAM-1. This may be one reason for the lack of inflammation in the irradiated rat liver.

The impact of prostate volume changes during external-beam irradiation in consequence of HDR brachytherapy in prostate cancer treatment.

PURPOSE: To evaluate prostate volume changes during external-beam irradiation in consequence of high-dose-rate (HDR) brachytherapy in prostate cancer treatment. PATIENTS AND METHODS: 20 patients who underwent radiotherapy for prostate cancer were included in this prospective evaluation. All patients had a computed tomography (CT) scan for planning of the external-beam irradiation and additional scans after each HDR brachytherapy. For the planning target volume (PTV), a safety margin of 10 mm was added to the clinical target volume (CTV) in each direction. The prostate volume measured in the planning CT was compared with the prostate volumes measured after HDR brachytherapy and, subsequently, the change of prostate volume was calculated. Volume changes which resulted in differences of the prostate radius of > 5 mm for the CTV were defined as a reason for a new treatment-planning procedure for the patient. RESULTS: Taking all patients together, prostate volumes before HDR, 1 day and 4-6 days after the first HDR treatment, as well as 1 day and 4-6 days after the second HDR treatment were in median 37.7 cm(3), 37.6 cm(3), 38.2 cm(3), 39.3 cm(3), and 40.5 cm(3), respectively. In none of the patient, a volume change resulted in a change of the prostate radius of > 5 mm for the CTV. Prerequisite for this calculation was the simplification of the complex prostate geometry to a sphere. No new treatment-planning procedure was necessary during external-beam radiotherapy. CONCLUSION: HDR brachytherapy does change the prostate volume. Under the condition of a 10-mm safety margin in each direction added to the CTV for the PTV, no new treatment-planning procedure was necessary after HDR brachytherapy. There is no need for CT scans at regular intervals during external-beam radiotherapy.

Organ function and quality of life after transoral laser microsurgery and adjuvant radiotherapy for locally advanced laryngeal cancer.

BACKGROUND AND PURPOSE: Transoral laser microsurgery (TLM) and adjuvant radiotherapy are an established therapy regimen for locally advanced laryngeal cancer at our institution. Aim of the present study was to assess value of quality of life (QoL) data with special regard to organ function under consideration of treatment efficacy in patients with locally advanced laryngeal cancer treated with larynx-preserving TLM and adjuvant radiotherapy. PATIENTS AND METHODS: From 1994 to 2006, 39 patients (ten UICC stage III, 29 UICC stage IVA/B) with locally advanced laryngeal carcinomas were treated with TLM and adjuvant radiotherapy. Data concerning treatment efficacy, QoL (using the VHI [Voice Handicap Index], the EORTC QLQ-C30 and QLQ-H&N35 questionnaires) and organ function (respiration, deglutition, voice quality) were obtained for ten patients still alive after long-term follow-up. Correlations were determined using the Spearman rank test. RESULTS: After a median follow-up of 80.8 months, the 5-year overall survival rate was 46.8% and the locoregional control rate 76.5%, respectively. The larynx preservation rate was 89.7% for all patients and 100% for patients still alive after follow-up. Despite some verifiable problems in respiration, speech and swallowing, patients showed a subjectively good QoL. CONCLUSION: TLM and adjuvant radiotherapy is a curative option for patients with locally advanced laryngeal cancer and an alternative to radical surgery. Even if functional deficits are unavoidable in the treatment of locally advanced laryngeal carcinomas, larynx preservation is associated with a subjectively good QoL.

In vivo dosimetry in the urethra using alanine/ESR during (192)Ir HDR brachytherapy of prostate cancer--a phantom study.

A phantom study for dosimetry in the urethra using alanine/ESR during (192)Ir HDR brachytherapy of prostate cancer is presented. The measurement method of the secondary standard of the Physikalisch-Technische Bundesanstalt had to be slightly modified in order to be able to measure inside a Foley catheter. The absorbed dose to water response of the alanine dosimetry system to (192)Ir was determined with a reproducibility of 1.8% relative to (60)Co. The resulting uncertainty for measurements inside the urethra was estimated to be 3.6%, excluding the uncertainty of the dose rate constant Lambda. The applied dose calculated by a treatment planning system is compared to the measured dose for a small series of (192)Ir HDR irradiations in a gel phantom. The differences between the measured and applied dose are well within the limits of uncertainty. Therefore, the method is considered to be suitable for measurements in vivo.

Fluence-weighted average subfield size in helical TomoTherapy.

INTRODUCTION: Helical TomoTherapy allows a highly conformal dose distribution to complex target geometries with a good protection of organs at risk. However, the small field sizes associated with this method are a possible source of dosimetrical uncertainties. The IAEA has published detector-specific field output correction factors for static fields of the TomoTherapy in the TRS483. This work investigates the average subfield size of helical TomoTherapy plans. MATERIAL AND METHODS: A new parameter for helical TomoTherapy was defined - the fluence-weighted average subfield size. The subfield sizes were extracted from the leaf-opening time sinograms in the RT-plan files for 30 clinical prostate and head and neck plans and were put in relation to Delat4 Phantom+ measurement results. Additionally the influence of planning parameters on the subfield size was studied by varying the modulation factor, number of iterations and pitch in the dose optimization and calculation for three different clinical indications H&N, prostate and rectum cancer. Selected plans were dosimetrically verified by Delta4 measurements to examine the reliability in dependence of the average subfield size. Furthermore, the impact of the planning parameters on a) the dose distribution, with regard to the planning target volume and regions at risks, and b) machine characteristics such as delivery time, actual modulation factor and leaf-opening times were evaluated. RESULTS: The average equivalent square subfield lengths (s¯eq) of the two investigated indications did not differ significantly - prostate plans: 2.75±0.14cm and H&N plans: 2.70±0.16cm, both with a jaw width of 2.5cm. No correlation between field size and measured dose deviation was detected. The number of iterations and the modulation factor have a considerable influence on the average subfield size. The higher the planned modulation factor and the more iterations are used during optimization, the smaller is the subfield size. In our pilot study plans were calculated with field sizes s¯eq between 4.2cm and 1.7cm, with a jaw width of 2.5cm. Again, the measurement results of Delta4 showed no significant deviation from the doses calculated by the TomoTherapy planning system for the whole range of subfield sizes, and no significant correlation between field sizes and dose deviations was found. As expected, the clinical dose distribution improved with increasing modulation factor and an increasing number of iterations. The compromise between an improved dose distribution and smaller s¯eq was shown. CONCLUSION: In this work, a method was presented to determine the average subfield size for helical TomoTherapy plans. The response of the Delta4 did not show any dependence on field size in the range of the field sizes covered by the studied plans. The influence of the subfield sizes on other dosimetry systems remains to be investigated.

The significance of a uniform definition of pathological lymph nodes in Hodgkin lymphoma: impact of different thresholds for positive lymph nodes in CT imaging on staging and therapy.

BACKGROUND AND PURPOSE: The most commonly used approach for the assessment for differentiating malignant versus reactive lymph nodes is the measurement of the cross-section diameter of the lymph nodes in the transversal CT-planes. The intention of this article is to assess the impact of varying definitions of pathological lymph node size in CT-imaging in patients with Hodgkin lymphoma and to evaluate its effect on staging, chemotherapy regimes and radiation field size. MATERIALS AND METHODS: Pretherapeutic CT-scans of 10 consecutive patients with Hodgkin lymphoma have been evaluated based on two different definitions for malignant lymph node size; the classification of the German study group for Hodgkin lymphoma (1.0 cm) and the classification according to the results of the Cotswold consensus meeting 1989 (1.5 cm). RESULTS: Applying the definitions of the DHSG and the Cotswold meeting we found more affected lymph node regions compared to the evaluation of the referring institutions in 9/10 and 6/10 patients, higher stages in 2/10 and 1/10 patients, more intense chemotherapy regimes in 3/10 and 1/10 and larger radiation fields in 10/10 and 6/10 patients, respectively. CONCLUSIONS: Varying definitions of pathologic lymph node size and inconsequent application of definitions reduce the comparability between different studies and within each study.

In vivo alanine/electron spin resonance (ESR) dosimetry in radiotherapy of prostate cancer: a feasibility study.

PURPOSE: We have developed a device to evaluate the potential of alanine/electron spin resonance (ESR) dosimetry for quality assurance in 3D conformal radiotherapy for prostate cancer. It consists of a rectal balloon carrying eight alanine dosimeter probes and two metal markers to document the exact position of the balloon. We measured the effects of an air-filled rectal balloon on the dose at the rectal wall and compared these results with the applied dose distribution of the treatment planning system. MATERIALS AND METHODS: During 10 fractions with 2.0 Gy per fraction, the accumulated doses were measured in 3 patients. The results of the ESR measurements were compared to the applied doses. RESULTS: It was possible to insert the device without clinical complications and without additional rectal discomfort for the patients. The measurements of the dose accumulated at the anterior and the posterior rectal wall agreed with the applied dose within a mean deviation of 1.5% (overestimation of the dose) and 3.5% (underestimation of the dose), respectively. However, clinically significant differences between applied and measured rectal doses were seen in a patient with a hip prosthesis. In this case, the dose at the anterior rectal wall was overestimated by the TPS by about 11% and the dose at the posterior rectal wall was underestimated by approximately 7%. CONCLUSION: The method presented in this study is useful for quality control of irradiations in vivo.

An easy irradiation technique (partial half-beam) to reduce renal dose in radiotherapy of cervical cancer including paraaortic lymph nodes.

PURPOSE: : For radiation treatment of patients with cervical cancer and a high risk for paraaortic lymph node involvement, an easy three-dimensional (3-D) conformal irradiation technique (partial half-beam [PHB]) for protection of organs at risk, especially of renal tissue, was developed. PATIENTS AND METHODS: : In five consecutive female patients a computed tomography scan was performed. Dose-volume histograms of the renal tissue and other organs at risk were analyzed for PHB, three other 3-D conformal techniques, and an intensitymodulated radiotherapy (IMRT) technique. RESULTS: : The PHB technique reduced the renal volume and volumes of other organs at risk exposed to radiation doses when comparing all patients to the other 3-D conformal techniques. With use of the IMRT technique more renal tissue volume received very low radiation doses (

A special device (double-hole belly board) and optimal radiation technique to reduce testicular radiation exposure in radiotherapy of rectal cancer.

PURPOSE: Patients with rectal cancer are treated in prone position on a belly board to reduce the volume of irradiated small bowel. With this technique the testes obtain radiation doses, which often result in partial or complete impairment of the spermatogenesis and a dose-dependent decrease of testosterone levels. We developed a double-hole belly board (DHBB) and evaluated its potential to reduce testicular dose. METHODS AND MATERIALS: In nine consecutive male patients (3 very low tumor localisations [inguinal RT], 3 low [RT perineum], 3 high [lower border ischial tuberosities]) CT scans were performed on a conventional single-hole belly board (SHBB) and on a DHBB. Dose-volume histograms of the testes were analysed for both belly boards and for different treatment techniques (3-field and 4-field). RESULTS: To reduce testicular dose in high tumors, positioning on DHBB was most effective (V(1.5Gy) 20-30% vs. 60% for SHBB, V(4Gy) 7% vs. 35%). In low tumors, a 3-field technique reduced high testicular doses (V(14Gy) 0-6% vs. 28-34% for 4-fields). In very low tumors a combination of DHBB and 3-fields led to a decrease of high dose exposure (V(33Gy) 0% vs. 24-78%). CONCLUSION: In male patients with rectal cancer the use of a DHBB and a 3-field technique is recommended to reduce testicular radiation exposure.

Impact of Different Treatment Concepts on Regional Failure in Advanced Oropharyngeal Cancer.

BACKGROUND: The management of patients with advanced oropharyngeal cancer is complex and mostly requires a multidisciplinary treatment approach. In general, organ preservation by primary concurrent radiochemotherapy (RCT), or surgery completed by adjuvant radiotherapy are established treatment strategies for these patients. However, it is unclear if primary treatment has an effect on regional tumor control. The purpose of the present study was to evaluate the regional control after different treatment concepts. PATIENTS AND METHODS: Clinical data, including histological and radiological results, of 82 patients with T2-T3 oropharyngeal cancer and N2 neck were retrospectively analyzed. They underwent either RCT with salvage neck dissection (ND) (n=45), or primary transoral surgery with ND and adjuvant RCT (n=37). In all cases, the primary tumor was successfully treated, without evidence of local failure in the follow-up. RESULTS: Overall, 11 (13.4%) patients developed regional failure during the follow-up. There were no significant differences in frequency of regional failure (p=0.75), distant metastasis (p=0.35) and overall survival (p=0.22) between treatment groups. However, 5-year disease-free survival was significantly worse (39.0% vs. 57.0%) for patients treated by RCT, with more frequent regional failure detected compared to surgically-treated patients in univariate analysis (p=0.04). CONCLUSION: Treatment concept does not seem to affect regional tumor control in advanced oropharyngeal cancer after successful treatment of the primary tumor.