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At least 19 recordsLinked to original sources
PubMed2004

IMRT for the treatment of prostate cancer: a comparison of a forward-planned technique and an inverse-planned technique utilizing a dose gradient method.

Radiation therapy has been a major treatment option for patients with prostate cancer with documented efficacy over the last 30 years. Recent research has shown a correlation between improved local control, disease-free survival, and overall survival and dose delivered. Excessive dose to the rectum is one of the leading causes of morbidity in the treatment of prostate cancer. The RTOG and others have suggested dose limitations based on various treatment parameters. Intensity-modulated radiation therapy (IMRT) is becoming more widely used, with the goal of improving dose coverage while limiting morbidity. In an effort to evaluate our inverse-planning technique relative to our forward-planned technique based on rectal dose, 2 plans were generated on 10 patients. One plan was generated with 9-field forward planning, using 2 posterior obliques to decrease dose to the rectum. The other plan utilized inverse IMRTplanning. To evaluate dose to the rectum, we compared the dose gradient from the posterior edge of the prostate across the anterior third of the rectal wall. This gradient, which is not part of the IMRT planning objectives, proved useful in assessing plan differences, and led to new dose objectives for certain IMRT plans.

Disease-Free Survival↗
PubMed2002

Radical radiotherapy and salvage cystectomy as the primary management of transitional cell carcinoma of the bladder. Results following the introduction of a CT planning technique.

The objective of this study was to review the results of our policy of primary radiotherapy (RT) and salvage cystectomy for transitional carcinoma (TCC) of the bladder in the light of changes in our radiotherapy planning procedure, in particular the introduction of CT planning. The case notes of 163 patients treated with radical radiotherapy using a CT planning technique were examined. The main endpoint for assessment was response at the time of the check cystoscopy 6 months after the completion of treatment. In addition survival was estimated by stage of disease and by response at the time of first cystoscopy. Patterns of relapse and time to relapse were analysed. All percentages quoted in the text use the initial 163 patients as the denominator. One hundred patients (61%) achieved a complete response. The complete response rate was significantly related to T stage at presentation being 90% for T1, 75% for T2, and 53% for T3 disease respectively. Of these patients 78 remain disease free in the bladder (47%). Twenty-two have relapsed in the bladder, of whom 5 have also relapsed at metastatic sites. Fifteen patients have relapsed outside the bladder whilst remaining disease free within the bladder. At the time of last follow up or death from other causes 63 of the 100 patients who had a complete response remained disease free with an intact bladder. There were 18 (11%) partial responders. Seven of these patients went on to have a cystectomy. Ten remain alive, 7 disease free, 4 with intact bladders. In 24 patients (15%) there was no response and these patients have all died, the median survival being 10 months. In 21 patients (13%) a postradiotherapy cystoscopy was not performed. In all but one patient, who was lost to follow up, this was because of progressive disease. The median survival of these 20 patients was 6 months. Of the 163 patients 35% are alive and well with an intact bladder. If patients dying from other causes are included then 42% were rendered disease free. Cause specific survival was significantly related to stage of disease at presentation with 5 year actuarial survival being 87%, 48% and 26%, for T1, T2 and T3 disease respectively. Survival was also related to response to treatment at 6 months with 5 year survival being 64%, and 52% for complete and partial responders respectively. Survival was extremely poor for non-responders with only 37.5% surviving 1 year and none 5 years. There was a highly significant relationship between response and the development of, and the time to developing metastatic disease. Of those who exhibited a response 21% developed metastatic disease compared to 78% of non-responders. Salvage cystectomy offers the possibility of cure in those who achieve a complete or partial response with 42% of such patients being rendered disease free. Results however are poor in those who did not respond with all patients dying of their disease. Response rates for all stages, and survival for stages T1 and T2 are much improved from those previously reported from this centre and compare favourably with other published series. These results confirm the place of radiotherapy and salvage cystectomy in the management of TCC of the bladder in selected patients. In about one-third of patients the desired outcome of curing the patient of their cancer with organ preservation is achieved. The prognostic significance of cystoscopic response at 6 months and stage at presentation is confirmed. The outcome for patients with early stage disease is excellent. The relationship between response and the development of metastatic disease would suggest that even if these patients had had a primary cystectomy they may have fared badly, a conclusion supported by the fact that these results are comparable with surgical series. This series supports the role of radiotherapy in the management of this disease and suggests that modern RT techniques including CT planning have had a beneficial effect on the results of radical radiotherapy.

Aged↗
PubMed2004

Comparison of three IMRT inverse planning techniques that allow for partial esophagus sparing in patients receiving thoracic radiation therapy for lung cancer.

The purpose of this study is to compare 3 intensity-modulated radiation therapy (IMRT) inverse treatment planning techniques as applied to locally-advanced lung cancer. This study evaluates whether sufficient radiotherapy (RT) dose is given for durable control of tumors while sparing a portion of the esophagus, and whether large number of segments and monitor units are required. We selected 5 cases of locally-advanced lung cancer with large central tumor, abutting the esophagus. To ensure that no more than half of the esophagus circumference at any level received the specified dose limit, it was divided into disk-like sections and dose limits were imposed on each. Two sets of dose objectives were specified for tumor and other critical structures for standard dose RT and for dose escalation RT. Plans were generated using an aperture-based inverse planning (ABIP) technique with the Cimmino algorithm for optimization. Beamlet-based inverse treatment planning was carried out with a commercial simulated annealing package (CORVUS) and with an in-house system that used the Cimmino projection algorithm (CIMM). For 3 of the 5 cases, results met all of the constraints from the 3 techniques for the 2 sets of dose objectives. The CORVUS system without delivery efficiency consideration required the most segments and monitor units. The CIMM system reduced the number while the ABIP techniques showed a further reduction, although for one of the cases, a solution was not readily obtained using the ABIP technique for dose escalation objectives.

Esophagus↗
PubMed1998

A comparison of two planning techniques for radiotherapy of high grade astrocytomas.

The purpose of this study was to compare two planning techniques for the delivery of radical localized postoperative radiotherapy in the treatment of high grade astrocytomas. Conventional orthogonal plain film planning (CONP) was compared with CT planning (CTP) in terms of the size of the target volumes treated, the amount of normal brain irradiated and the accuracy of localization. Twenty consecutive adults with high grade astrocytomas, who were treated with radiotherapy between March and October 1996, were planned with CONP and CTP, using postoperative, contrast-enhanced CT scans to define the tumour volume. The planning target areas, volumes and the 100%, 80% and 50% isodose areas produced using the two planning methods were measured and compared using Student's paired t-test. The target volume length was also measured and compared as an independent factor. The difference between entry points of the central axis of the lateral fields was noted. Nineteen of 20 patients had a reduction in planning target volumes using CTP compared with CONP. The difference between the mean volumes was clinically relevant, with 288 cm3 representing a 25% reduction, and statistically significant at the P<0.001 level. The planning target volumes were reduced in 18/20 patients (mean 24 cm2, 23%, P<0.001). Similarly, there were highly significant reductions in the 100%, 80% and 50% isodose areas. The target volume lengths were not found to be significantly different. When considering the accuracy of localization, the entry point of the CONP lateral field deviated by a mean distance of 1.6 cm relative to CTP (superiorinferior 1.3 cm; anteriorposterior 0.8 cm; range 04.1 cm). In two patients, this would have led to a geographical miss of macroscopic disease. In patients with high grade astrocytomas, CTP is preferred to conventional planning. It leads to appreciable reductions in the size of the planning target areas and volumes receiving radical doses of radiation, it significantly reduces the amount of normal brain tissue being irradiated and is more accurate in terms of tumour localization. These differences are likely to lead to a reduction in treatment morbidity. We recommend CTP for all patients receiving radical radiotherapy.

Adult↗
PubMed2002

On the selection of optimization parameters for an inverse treatment planning replacement of a forward planning technique for prostate cancer.

The influence of organ volume sampling, lateral scatter inclusion, and the selection of objectives and constraints on the inverse treatment planning process with a commercial treatment planning system is investigated and suitable parameters are identified for an inverse treatment planning replacement of a clinical forward planning technique for prostate cancer. For the beam geometries of the forward technique, a variable set of parameters is used for the calculation of dose from pencil beams. An optimal set is identified after the evaluation of optimized plans that correspond to different sets of pencil-beam parameters. This set along with a single, optimized set of objectives and constraints is used to perform inverse planning on ten randomly selected patients. The acceptability of the resulting plans is verified by comparisons to the clinical ones calculated with the forward techniques. For the particular commercial treatment planning system, the default values of the pencil beam parameters are found adequate for inverse treatment planning. For all ten patients, the optimized, single set of objectives and constraints results in plans with target coverage comparable to that of the forward plans. Furthermore inverse treatment planning reduces the overall mean rectal and bladder doses by 4.8% and 5.8% of the prescription dose respectively. The study indicates that (i) inverse treatment planning results depend implicitly on the sampling of the dose distribution, (ii) inverse treatment planning results depend on the method used by the dose calculation model to account for scatter, and (iii) for certain sites, a single set of optimization parameters can be used for all patient plans.

Dose Fractionation, Radiation↗
PubMed2000

An optimized forward-planning technique for intensity modulated radiation therapy.

Intensity modulated radiation therapy (IMRT) has stirred considerable excitement in the radiation oncology community. Its objective is to make the dose conform to the tumor and spare other organs. Instead of resorting to the rather complex inverse-planning, the technique described here is an extension of the conventional treatment planning technique. The beam orientation and wedge angles are chosen in the conventional rule-based manner. However, within each conformal beam's eye view (BEV) field including margin, a number of sub-field openings are added. The smaller field openings are designed to irradiate the tumor, while sparing the normal tissue of the organs at risk (OARs) that intrude into the target region in the BEV. As the number of intrusions into the target BEV increases, the number of sub-fields for each beam increases. The Cimmino simultaneous projection method was employed to obtain the optimized weighting for each field of each beam. In cases where the dose constraints for the tumor and for the OARs are reasonable, it is possible to obtain a plan with a fairly small number of beams that satisfies the specified dose objectives. This is illustrated for the treatment of prostate cancer, where the rectum creates a concavity in the planning target volume. An advantage of this technique is that the quality assurance for the delivery of these plans does not require extensive special efforts.

Algorithms↗
PubMed2002

[Using network planning techniques for work flow analysis in a clinical environment].

In the face of increasing financial pressure on our health care system, one way to reduce costs while maintaining or even improving outcome quality is to improve work flow efficiency. Network Planning Technique (NPT) is a tool for mapping and analyzing work flows. Designing a network plan requires four steps. Step 1 is concerned with the determination of the work flow structure. Step 2 deals with data acquisition. Based on the data retrieved a network plan is created in Step 3. Step 4 includes the calculation of the critical path and slack times under optimistic, realistic and pessimistic conditions. Applied to the ultrasound division in our department a total examination time of 34:14 minutes was calculated with 23:09 minutes total slack time for the technician under realistic conditions. Using NPT creates transparency in work flows and allows us to estimate resource demands. A comparison between two different divisions with a similar work flow structure but different resource allocation demonstrates this method's potential for improving work flows. Limitations of the NPT can be noted when considering cycle overlap in repetitive work flows and modeling non-regular activities.

Diagnosis-Related Groups↗
PubMed1995

Advanced interactive planning techniques for conformal therapy: high level beam descriptions and volumetric mapping techniques.

PURPOSE: To aid in design of conformal radiation therapy treatment plans involving many conformally shaped fields, this work investigates the use of two methodologies to enhance the ease of interactive treatment planning: high-level beam constructs and beam's-eye view volumetric mapping. METHODS AND MATERIALS: High-performance computer graphics running on various workstations using a graphical visualization system (AVS) have been used in this work. Software specific to this application has been written in standard FORTRAN and C languages. A new methodology is introduced by defining radiation therapy "fields" to be composed of multiple beam "segments." Fields can then be defined as higher-level entities such as arcs, cones, and other shapes. A "segmental cone" field, for example, is defined by a symmetry axis and a cone angle, and can be used to rapidly place a series of beam segments that converge at the target volume, while reducing the degree of overlap elsewhere. A new beam's-eye view (BEV) volumetric mapping technique is presented to aid in selecting the placement of conformal radiation fields. With this technique, the relative average dose within an organ of interest is calculated for a sampling of isocentric, conformally shaped beams and displayed either as a "globe," which can be combined with the display of anatomical surfaces, or as a two-dimensionally mapped projection. The dose maps from multiple organs can be generated, stacked, or composited with relative weightings to aid in the placement of fields that minimize overlap with critical structures. RESULTS: The use of these new methodologies is demonstrated for prostate and lung treatment sites and compared to conventional planning techniques. DISCUSSION: The use of many beams for conformal treatment delivery is difficult with current interactive planning. The use of high-level beam constructs provides a means to quickly specify, place, and configure multiple beam arrangements. The BEV volumetrics aids in the placing of fields, which minimize involvement with critical normal tissues. CONCLUSIONS: Early experience with the new methodologies suggest that the new methods help to enhance (or at least speed up) the ability of a treatment planner to create optimal radiation treatment field arrangements.

Evaluation Studies as Topic↗
PubMed1985

Strategic competition: the application of business planning techniques to the hospital marketplace.

Survival in the increasingly turbulent and uncertain health care environment should raise the application of business planning and corporate strategy to the highest levels of institutional consciousness. With hospital mergers and networking arrangements expected to account for over 60% of the hospital beds in the nation by 1990, and with government and business cost containment efforts squeezing hospital margins, the survivors are going to be those institutions able to develop and maintain a sustainable economic advantage over the competition in the programs and services that comprise the major portion of their business. The successful players will be those that allow the institution to identify and exploit new opportunities and concentrate management and financial resources in those segments of the market where competitive advantages are real and attainable.

Culture↗
PubMed2002

Inverse treatment planning and stereotactic intensity-modulated radiation therapy (IMRT) of the tumor and lymph node levels for nasopharyngeal carcinomas. Description of treatment technique, plan comparison, and case study.

PURPOSE: Inverse treatment planning and intensity-modulated radiation therapy (IMRT) promise advantages in the treatment of tumors of the head and neck region. Currently published studies use IMRT only in the treatment of the primary tumor. In these studies, the lymph nodes of the neck were treated using conventional techniques. The feasibility of an IMRT technique which allows treatment of the complete target volume, including the primary tumor and lymph nodes, without a beam split is described. PATIENT AND METHOD: For inverse treatment planning, the KonRad planning system was used. The primary as well as the secondary PTV (bilateral lymph node levels) were treated with one intensity-modulated primary plan. To increase the dose in the primary PTV and suspicious lymph nodes, an intensity-modulated boost plan was performed. The "step and shoot" IMRT technique was used. A plan comparison between the described IMRT approach and an IMRT approach using a split-beam technique was performed focusing on the treatment time. A patient with a carcinoma of the nasopharynx was treated with curative intent by a combined radiochemotherapy. RESULTS: The median total dose to the primary PTV was 70 Gy, to suspicious lymph nodes > or = 66.0 Gy, and to the secondary PTV 52 Gy. The defined maximum doses to the organs at risk were not exceeded, and the median dose to the protected parotid gland amounted to 21 Gy. Comparison of the treatment time between both IMRT approaches revealed only a slightly shorter treatment time (1-3 min) for the split-beam IMRT technique without considering the remaining conventional treatment parts of the split-beam IMRT technique. The patient achieved a complete response, and 18 months after treatment no signs of recurrent disease are visible. CONCLUSIONS: IMRT allows the treatment of the target volumes with high doses combined with an excellent sparing of the organs at risk. The IMRT approach presented here makes the treatment of the whole target volume with a single-beam arrangement feasible and does not increase the treatment time compared to a split-beam IMRT technique. Treatment time was comparable to a conventional three-field technique combined with electrons. This IMRT technique can prevent over- or underdosage at field matchlines in the head and neck region and, moreover, is able to spare parotid glands and therefore better avoid xerostomia compared to conventional techniques.

Algorithms↗
PubMed1989

Focus groups: a program planning technique.

To successfully develop nurse retention programs, a thorough organizational analysis, including the identification of problems, is necessary. Used as a management tool, focus groups that use the organization's nursing staff provide a unique method of data collection for identifying problems that now exist in the organization. The authors discuss this method for obtaining information for strategic planning for retention of nurses.

Job Satisfaction↗
PubMed1979

Computed tomography applied to radiotherapy treatment planning: techniques and results.

In order to assess the role of computed tomography (CT) in radiotherapy treatment planning, tumors were localized by conventional techniques and with CT using an EMI CT5005 scanner. CT scans were obtained under conditions simulating radiotherapy. A comparison between the two localizations was made, and detailed results are given. Forty-seven of 123 patients had their treatment plan altered, implying that, provided information is obtained and used correctly, CT can play a significant role in radiotherapy treatment planning.

Abdominal Neoplasms↗