Beamlet based direct aperture optimization for MERT using a photon MLC.

PURPOSE: A beamlet based direct aperture optimization (DAO) for modulated electron radiotherapy (MERT) using photon multileaf collimator (pMLC) shaped electron fields is developed and investigated. METHODS: The Swiss Monte Carlo Plan (SMCP) allows the calculation of dose distributions for pMLC shaped electron beams. SMCP is interfaced with the Eclipse TPS (Varian Medical Systems, Palo Alto, CA) which can thus be included into the inverse treatment planning process for MERT. This process starts with the import of a CT-scan into Eclipse, the contouring of the target and the organs at risk (OARs), and the choice of the initial electron beam directions. For each electron beam, the number of apertures, their energy, and initial shape are defined. Furthermore, the DAO requires dose-volume constraints for the structures contoured. In order to carry out the DAO efficiently, the initial electron beams are divided into a grid of beamlets. For each of those, the dose distribution is precalculated using a modified electron beam model, resulting in a dose list for each beamlet and energy. Then the DAO is carried out, leading to a set of optimal apertures and corresponding weights. These optimal apertures are now converted into pMLC shaped segments and the dose calculation for each segment is performed. For these dose distributions, a weight optimization process is launched in order to minimize the differences between the dose distribution using the optimal apertures and the pMLC segments. Finally, a deliverable dose distribution for the MERT plan is obtained and loaded back into Eclipse for evaluation. For an idealized water phantom geometry, a MERT treatment plan is created and compared to the plan obtained using a previously developed forward planning strategy. Further, MERT treatment plans for three clinical situations (breast, chest wall, and parotid metastasis of a squamous cell skin carcinoma) are created using the developed inverse planning strategy. The MERT plans are compared to clinical standard treatment plans using photon beams and the differences between the optimal and the deliverable dose distributions are determined. RESULTS: For the idealized water phantom geometry, the inversely optimized MERT plan is able to obtain the same PTV coverage, but with an improved OAR sparing compared to the forwardly optimized plan. Regarding the right-sided breast case, the MERT plan is able to reduce the lung volume receiving more than 30% of the prescribed dose and the mean lung dose compared to the standard plan. However, the standard plan leads to a better homogeneity within the CTV. The results for the left-sided thorax wall are similar but also the dose to the heart is reduced comparing MERT to the standard treatment plan. For the parotid case, MERT leads to lower doses for almost all OARs but to a less homogeneous dose distribution for the PTV when compared to a standard plan. For all cases, the weight optimization successfully minimized the differences between the optimal and the deliverable dose distribution. CONCLUSIONS: A beamlet based DAO using multiple beam angles is implemented and successfully tested for an idealized water phantom geometry and clinical situations.

Forward treatment planning for modulated electron radiotherapy (MERT) employing Monte Carlo methods.

PURPOSE: This paper describes the development of a forward planning process for modulated electron radiotherapy (MERT). The approach is based on a previously developed electron beam model used to calculate dose distributions of electron beams shaped by a photon multi leaf collimator (pMLC). METHODS: As the electron beam model has already been implemented into the Swiss Monte Carlo Plan environment, the Eclipse treatment planning system (Varian Medical Systems, Palo Alto, CA) can be included in the planning process for MERT. In a first step, CT data are imported into Eclipse and a pMLC shaped electron beam is set up. This initial electron beam is then divided into segments, with the electron energy in each segment chosen according to the distal depth of the planning target volume (PTV) in beam direction. In order to improve the homogeneity of the dose distribution in the PTV, a feathering process (Gaussian edge feathering) is launched, which results in a number of feathered segments. For each of these segments a dose calculation is performed employing the in-house developed electron beam model along with the macro Monte Carlo dose calculation algorithm. Finally, an automated weight optimization of all segments is carried out and the total dose distribution is read back into Eclipse for display and evaluation. One academic and two clinical situations are investigated for possible benefits of MERT treatment compared to standard treatments performed in our clinics and treatment with a bolus electron conformal (BolusECT) method. RESULTS: The MERT treatment plan of the academic case was superior to the standard single segment electron treatment plan in terms of organs at risk (OAR) sparing. Further, a comparison between an unfeathered and a feathered MERT plan showed better PTV coverage and homogeneity for the feathered plan, with V95% increased from 90% to 96% and V107% decreased from 8% to nearly 0%. For a clinical breast boost irradiation, the MERT plan led to a similar homogeneity in the PTV compared to the standard treatment plan while the mean body dose was lower for the MERT plan. Regarding the second clinical case, a whole breast treatment, MERT resulted in a reduction of the lung volume receiving more than 45% of the prescribed dose when compared to the standard plan. On the other hand, the MERT plan leads to a larger low-dose lung volume and a degraded dose homogeneity in the PTV. For the clinical cases evaluated in this work, treatment plans using the BolusECT technique resulted in a more homogenous PTV and CTV coverage but higher doses to the OARs than the MERT plans. CONCLUSIONS: MERT treatments were successfully planned for phantom and clinical cases, applying a newly developed intuitive and efficient forward planning strategy that employs a MC based electron beam model for pMLC shaped electron beams. It is shown that MERT can lead to a dose reduction in OARs compared to other methods. The process of feathering MERT segments results in an improvement of the dose homogeneity in the PTV.

Monte Carlo based beam model using a photon MLC for modulated electron radiotherapy.

PURPOSE: Modulated electron radiotherapy (MERT) promises sparing of organs at risk for certain tumor sites. Any implementation of MERT treatment planning requires an accurate beam model. The aim of this work is the development of a beam model which reconstructs electron fields shaped using the Millennium photon multileaf collimator (MLC) (Varian Medical Systems, Inc., Palo Alto, CA) for a Varian linear accelerator (linac). METHODS: This beam model is divided into an analytical part (two photon and two electron sources) and a Monte Carlo (MC) transport through the MLC. For dose calculation purposes the beam model has been coupled with a macro MC dose calculation algorithm. The commissioning process requires a set of measurements and precalculated MC input. The beam model has been commissioned at a source to surface distance of 70 cm for a Clinac 23EX (Varian Medical Systems, Inc., Palo Alto, CA) and a TrueBeam linac (Varian Medical Systems, Inc., Palo Alto, CA). For validation purposes, measured and calculated depth dose curves and dose profiles are compared for four different MLC shaped electron fields and all available energies. Furthermore, a measured two-dimensional dose distribution for patched segments consisting of three 18 MeV segments, three 12 MeV segments, and a 9 MeV segment is compared with corresponding dose calculations. Finally, measured and calculated two-dimensional dose distributions are compared for a circular segment encompassed with a C-shaped segment. RESULTS: For 15 × 34, 5 × 5, and 2 × 2 cm(2) fields differences between water phantom measurements and calculations using the beam model coupled with the macro MC dose calculation algorithm are generally within 2% of the maximal dose value or 2 mm distance to agreement (DTA) for all electron beam energies. For a more complex MLC pattern, differences between measurements and calculations are generally within 3% of the maximal dose value or 3 mm DTA for all electron beam energies. For the two-dimensional dose comparisons, the differences between calculations and measurements are generally within 2% of the maximal dose value or 2 mm DTA. CONCLUSIONS: The results of the dose comparisons suggest that the developed beam model is suitable to accurately reconstruct photon MLC shaped electron beams for a Clinac 23EX and a TrueBeam linac. Hence, in future work the beam model will be utilized to investigate the possibilities of MERT using the photon MLC to shape electron beams.

Chemotherapy in patients with advanced pancreatic cancer: too close to death?

PURPOSE: We evaluated the attitude in using chemotherapy near the end of life in advanced pancreatic adenocarcinoma (PAC). Clinical and laboratory parameters recorded at last chemotherapy administration were analyzed, in order to identify risk factors for imminent death. METHODS: Retrospective analysis of patients who underwent at least one line of palliative chemotherapy was made. Data concerning chemotherapy (regimens, lines, and date of last administration) were collected. Clinical and laboratory factors recorded at last chemotherapy administration were: performance status, presence of ascites, hemoglobin, white blood cell (WBC), platelets, total bilirubin, albumin, LDH, C-reactive protein (C-rp), and Ca 19.9. RESULTS: We analyzed 231 patients: males/females, 53/47 %; metastatic/locally advanced disease, 80/20 %; and median age, 66 years (range 32-85). All patients died due to disease progression. Median overall survival was 6.1 months (95 % CI 5.1-7.2). At the last chemotherapy delivery, performance status was 0-1 in 37 % and 2 in 63 %. Fifty-nine percent of patients received one chemotherapy line, while 32, 8, and 1 % had second-, third-, and fourth line, respectively. The interval between last chemotherapy administration and death was <4 weeks in 24 %, ≥4-12 in 47 %, and >12 in 29 %. Median survival from last chemotherapy to death was 7.5 weeks (95 % CI 6.7-8.4). In a univariate analysis, ascites, elevated WBC, bilirubin, LDH, C-rp and Ca 19.9, and reduced albumin were found to predict shorter survival; however, none of them remained significant in a multivariate analysis. CONCLUSIONS: A significant proportion of patients with advanced PAC received chemotherapy within the last month of life. The clinical and laboratory parameters recorded at last chemotherapy delivery did not predict shorter survival.

Collapsed cone convolution and analytical anisotropic algorithm dose calculations compared to VMC++ Monte Carlo simulations in clinical cases.

The purpose of this work was to study and quantify the differences in dose distributions computed with some of the newest dose calculation algorithms available in commercial planning systems. The study was done for clinical cases originally calculated with pencil beam convolution (PBC) where large density inhomogeneities were present. Three other dose algorithms were used: a pencil beam like algorithm, the anisotropic analytic algorithm (AAA), a convolution superposition algorithm, collapsed cone convolution (CCC), and a Monte Carlo program, voxel Monte Carlo (VMC++). The dose calculation algorithms were compared under static field irradiations at 6 MV and 15 MV using multileaf collimators and hard wedges where necessary. Five clinical cases were studied: three lung and two breast cases. We found that, in terms of accuracy, the CCC algorithm performed better overall than AAA compared to VMC++, but AAA remains an attractive option for routine use in the clinic due to its short computation times. Dose differences between the different algorithms and VMC++ for the median value of the planning target volume (PTV) were typically 0.4% (range: 0.0 to 1.4%) in the lung and -1.3% (range: -2.1 to -0.6%) in the breast for the few cases we analysed. As expected, PTV coverage and dose homogeneity turned out to be more critical in the lung than in the breast cases with respect to the accuracy of the dose calculation. This was observed in the dose volume histograms obtained from the Monte Carlo simulations.

Attitudes toward euthanasia and physician assisted suicide: a survey among medical students, oncology clinicians, and palliative care specialists.

OBJECTIVE: The aim of this study was to compare the results of surveys about attitudes toward euthanasia and related issues that was conducted among palliative care specialists, health care professionals of a cancer center, and first- and second-year medical students. METHODS: By means of an anonymous questionnaire with different hypothetical scenarios concerning physician assisted suicide (PAS) and related issues, 726 members of the Swiss Association for Palliative Care (SAPC), 148 health care professionals of the Institute of Oncology of Italian speaking Switzerland (IOSI), and 140 medical students of the University of Fribourg, Switzerland, were surveyed. RESULTS: Among palliative care specialists a decreasing number supported PAS, direct active euthanasia (DAE), DAE for psychiatric patients, DAE in incompetent patients, and life terminating acts without explicit request (LAWER). Professionals of the cancer center were more in favor of DAE and PAS than palliative care specialists, but less in favor than medical students. SIGNIFICANCE OF RESULTS: Significant variations among different professionals exist in attitudes toward euthanasia. The hypothesis that familiarity with the care of severely ill and dying patients is an important underlying factor explaining variance has been confirmed by these surveys.

Lessons from an Ukrainian woman with clubbing and back pain.

We present this case that we consider of particular interest in palliative care because of the difficulty we encountered in palliating the patient's symptoms. The difficulties derived, at least in part, from particular personality traits and complex social circumstances. We think this case is an excellent example to demonstrate the complexity of the process of pain and the different resources and techniques that can be used to manage it. We also wish to underline the importance of clinical signs in diagnosis. In fact, this patient showed signs compatible with Pierre-Marie disease (or pulmonary hypertrophic osteoarthropathy, HOA). Finally, we would like to restate a possible link between neoplastic syndromes and the Chernobyl radiation disaster.

[Fatigue]. / Müdigkeit.

Fatigue is a highly prevalent symptom in cancer patients. However in the daily practice this issue doesn't get adequate attention, because of limited therapeutic tools. A number of research issues in this field has been started during the last few years. Some of these new findings will soon modify and improve treatment options. In the meantime it is worthwhile to identify etiologic factors. Some of them might be treated with a reasonable cost/benefit ratio, aiming to improve function and therefore the health related quality of life.

Selective pericyte degeneration in the retinal capillaries of galactose-fed dogs results from apoptosis linked to aldose reductase-catalyzed galactitol accumulation.

Galactose-fed dogs develop retinal capillary changes similar to diabetic retinopathy with pericyte degeneration as the initial lesion. This is followed by the formation of microaneurysms, hemorrhages, and some areas of acellularity. To investigate the mechanisms for selective pericyte degeneration, retinal capillary pericytes and endothelial cells isolated from beagle dog retina were cultured for 2 weeks in Dulbecco's modified Eagle's medium (DMEM) containing 50 mM D-galactose. Apoptosis was detected in pericytes but not endothelial cells by in situ terminal deoxynucleotidyl transferase (TdT)-mediated biotin-dUTP nick end labelling (TUNEL) staining and the DNA fragmentation assay on agarose gel electrophoresis. This apoptosis was prevented by the addition of the aldose reductase inhibitor AL 1576 to the culture medium containing galactose. Apoptosis was not observed when pericytes were similarly cultured in control DMEM medium. These data support the premise that the selective degeneration of retinal capillary pericytes observed in galactose-fed dogs is linked to increased aldose reductase activity in these cells.

"Euthanasia": a survey by the Swiss Association for Palliative Care.

Since the Swiss Association for Palliative Care (SAPC) considers itself an important partner in the national debate on euthanasia, the Board decided to conduct a survey among its members. An anonymous questionnaire was sent to the 726 members of the SAPC, consisting of multiple choice questions on positions that might be adopted in different hypothetical scenarios and one open question about the rationale for the answers. The response rate achieved with one mailing was 55.6%. The proportions of the respondents who were opposed to different forms of euthanasia were, in ascending order: 56% opposed to physician-assisted suicide (PAS); 69% to direct active euthanasia (DAE); 75% to DAE for psychiatric patients; 84% to delegation of DAE in the case of incompetent patients; and 90% to life-terminating acts without explicit requests (LAWER). Almost 10% of the members reported personal experiences with PAS and different forms of DAE. The main decisional bases drawn on for the answers were ethical values and the clinical or personal experience of the respondents; however, the same categories of arguments were used both by those opposing and by those favouring DAE. There are important variations among the members of the SAPC in the debate on euthanasia. Individual autonomy seems to be an important underlying concept for the different positions; the categories of arguments cited by opponents and supporters of DAE did not differ.

[Opiates on the upswing--are there really unproblematic?]. / Opiate im Aufwind--Sind sie wirklich unproblematisch?

Although morphine is known for almost 200 years as analgesic a considerable resistance is encountered regarding its use and prescription. This may only in part derive from cultural and political reasons mainly, however, from the widespread but usually unfounded fear of side effects. This article tries to put these fears in perspective. Morphine is a hardly toxic drug in the hands of the clinician aware of the side effects and willing to search for them. Possibilities how to avoid side effects and alternatives to morphine are proposed.

Palliative care of cancer patients: audit of current hospital procedures.

The palliative care of cancer patients admitted for tumour-related symptoms to three different departments (medical oncology, radiotherapy, internal medicine) of a general hospital was prospectively audited. The physicians directly responsible for the patients provided prospective data by reporting both the diagnostic and therapeutic interventions performed and the degree of control achieved for each symptom. A patient form for evaluation of the control achieved in the case of each symptom by means of linear analogue scales was also provided. The appropriateness of all procedures was evaluated by two external auditors. Over 6 months, 125 such admissions were recorded: 24 patients entered the study and the management of 56 symptoms, the most common of which were pain and dyspnoea, was reviewed. A total of 72 diagnostic procedures were performed, deemed necessary for only 50% of symptoms, optional for 15%, and performed as part of a logical sequence for 38%. A total of 130 therapeutic interventions were undertaken, deemed necessary for 55% of symptoms, optional for 15% and carried out as part of a logical sequence for 44%. Re-evaluations of symptoms and physician and patient evaluations of the degree of control achieved could not be assessed because of lack of information. The audit could not be repeated owing to the low accrual of patients and incompleteness of the data collection. Reasons for failure of the study and proposals for feasible methods of auditing the management of symptoms in cancer patients are discussed.

Matching the clinical function and symptom status with the expectations of patients with advanced cancer, their families, and health care workers.

Continuous accurate assessment is mandatory for palliative care of good quality. One of the major objectives in palliation is to meet the expectations of patient, family members and care givers. While a number of valid tools for assessing symptoms or function are available, there are unfortunately no recognized instruments for assessing expectations. The mismatch of expectations and the actual situation is a major source of distress and conflict. The present paper describes a simple way of visualizing this distress and conflict graphically. In our experience, this method is helpful in raising awareness of and enabling analysis of distress and conflict in patients, family members, and health care workers. It is also useful in the education of students and members of the palliative care team. It is illustrated with reference to four clinical situations.

Dose-dependent reduction of retinal vessel changes associated with diabetic retinopathy in galactose-fed dogs by the aldose reductase inhibitor M79175.

The onset and progression of retinal vascular changes associated with early diabetic retinopathy has been delayed in beagles fed 30% galactose diet for 38 months by treatment with the aldose reductase inhibitor M79175 (2-methyl-6-fluoro-spirochroman-4-5'- imidazolidine-2',4'-dione). Forty 9-month old male beagles were fed a daily diet containing either 30% non-nutrient filler or 30% galactose. One group of galactose-fed dogs was untreated while the others received M79175 at an average group dose of either 10 or 16 mg/kg/day. After 38 months one eye from 4 dogs from each group was enucleated and the isolated retinal vasculatures were objectively evaluated using an Olympus Cue-3 color image analysis system. Measurements of endothelium/pericyte (E/P) ratios, pericyte ghosts/1000 cells, pericytes and endothelial densities, and % acellularity per area and % acellularity per capillary length were conducted on a 0.1 mm square area surrounding the midpoints of 12 previously defined subregions. With the exception of endothelial densities which were not changed in galactose-fed dogs, M79175 treatment resulted in smaller changes in all parameters examined with the E/P ratio in dogs treated with 16 mg/kg/day M79175 not significantly different from that of age-matched non-galactose-fed dogs. These studies indicate that aldose reductase inhibitors provide dose-dependent protection against pericyte degeneration and subsequent microaneurysms formation.

The last 3 months of life of cancer patients: medical aspects and role of home-care services in southern Switzerland.

The clinical data on terminal cancer patients who have died since the establishment of a program of collaboration between community services and the cancer center of Canton of Ticino, southern Switzerland, were retrospectively analyzed to describe the characteristics of patients seen and the effect on them of a home-care program coordinated by the cancer center. The home-care program is based on five geographically grouped community-based domiciliary services, with the addition of one nurse responsible for coordination and one physician from the oncology center. Selection criteria for participation in the home-care program are defined. The main outcome measures were: number of hospitalizations and median hospital stay during the last 3 months of life; reasons for and median length of last hospitalization; place of death of patients who had home care and those who did not. In the group of 993 patients analyzed, the median contact time with the cancer center was 9.5 months (10th percentile: 1 month, 90th percentile: 71 months); the most frequent neoplasm was lung cancer (22%) with the briefest contact time (7.5 months; 10th percentile: 1 month; 90th percentile: 21 months); 13.5% of patients were never hospitalized; half of the patients had a total hospital stay of 24 days or longer and 23% died at home. The sociodemographic and medical characteristics of home-care users were similar to those of the home-care non-users and to those of the overall group. In the group of home-care users (32% of the total) 22% were never hospitalized, half of the patients had a total hospital stay of 17 days or longer, and 43.5% of them died at home. These values were significantly different (P > 0.001) from those reported in the group of home-care non-users. Palliative care, provided at home through community-based domiciliary services, is associated with less frequent and shorter hospitalizations in the last 3 months of life. Medical oncology and palliative treatments should be mutually complementary to improve patients care. Cancer centers should be involved in the planning and coordination of supportive-care domiciliary services.

Guidelines on artificial nutrition versus hydration in terminal cancer patients. European Association for Palliative Care.

Whether a terminally ill cancer patient should be actively fed or simply hydrated through subcutaneous or intravenous infusion of isotonic fluids is a matter of ongoing controversy among clinicians involved in the care of these patients. Under the auspices of the European Association for Palliative Care, a committee of experts developed guidelines to help clinicians make a reasonable decision on what type of nutritional support should be provided on a case-by-case basis. It was acknowledged that part of the controversy related to the definition of the terminal cancer patient, since this is a heterogeneous group of patients with different needs, expectations, and potential for a medical intervention. A major difficulty is the prediction of life expectancy and the patient's likely response to vigorous nutritional support. In an attempt to reach a decision on the type of treatment support (artificial nutrition vs. hydration) which would best meet the needs and expectations of the patient, we propose a three-step process: Step 1: define the eight key elements necessary to reach a decision; Step II: make the decision; and Step III: reevaluate the patient and the proposed treatment at specified intervals. Step I involves assessing the patient concerning the following: 1) oncological/clinical condition; 2) symptoms; 3) expected length of survival; 4) hydration and nutritional status; 5) spontaneous or voluntary nutrient intake; 6) psychological profile; 7) gut function and potential route of administration; and 8) need for special services based on type of nutritional support prescribed. Step II involves the overall assessment of pros and cons, based on information determined in Step I, in order to reach an appropriate decision based on a well-defined end point (i.e., improvement of quality of life; maintaining patient survival; attaining rehydration). Step III involves the periodic reevaluation of the decision made in Step II based on the proposed goal and the attained result.

Hospice--a homecare service for terminally ill cancer patients in southern Switzerland.

We describe the circumstances that led to the building up of a home care service for terminally ill cancer patients in a part of southern Switzerland. We describe the goals, the structure and the functioning of this service as it works in two areas. We give some results of a retrospective study on hospitalization, home care and death at home.

Endothelial changes in galactose-fed dogs.

Specular microscopic studies indicate that the size (polymegathism) and shape (pleomorphism) of the hexagonal corneal endothelial cells change in diabetics. Similar morphometric changes of the corneal endothelium have also been experimentally observed in diabetic rats as well as in diabetic and galactose-fed dogs and concomitant administration of aldose reductase inhibitors reduced these morphological changes. The purpose of this study was to examine whether corneal endothelial changes in galactose-fed dogs are reversible by the marked reduction of galactitol production after stopping prolonged galactose feeding. Ten control dogs were fed a normal diet, while 48 dogs were fed a diet containing 30% galactose. The galactose diet was removed from 15 dogs after 24 months at which time pericyte ghosts in the retina had developed and another 15 dogs were removed from the galactose diet after 31 months when retinal microaneurysms had developed. Eighteen dogs remained on galactose diet throughout the study (38 months). Specular microscopy was conducted on members of all groups after 38 months of study and the photographs were analyzed in masked fashion on the Bambi image analysis system. The evaluation of the corneal endothelial cells revealed significant differences in the cell size and density between galactose-fed dogs in the three groups and normal, age-matched control dogs. Corneal endothelial changes were not significantly reduced in dogs fed galactose for either 24 months or 31 months and then fed a normal diet for 14 and 7 months, respectively, indicating that amelioration of endothelial cell changes requires therapy prior to the advent of endothelial morphologic changes.