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G J Kutcher

Publications and source records attributed to G J Kutcher.

At least 19 recordsLinked to original sources
PubMed1991

Fitting of normal tissue tolerance data to an analytic function.

During external beam radiotherapy, normal tissues are irradiated along with the tumor. Radiation therapists try to minimize the dose of normal tissues while delivering a high dose to the target volume. Often this is difficult and complications arise due to irradiation of normal tissues. These complications depend not only on the dose but also on volume of the organ irradiated. Lyman has suggested a four-parameter empirical model which can be used to represent normal tissue response under conditions of uniform irradiation to whole and partial volumes as a function of the dose and volume irradiated. In this paper, Lyman's model has been applied to a compilation of clinical tolerance data developed by Emami et al. The four parameters to characterize the tissue response have been determined and graphical representations of the derived probability distributions are presented. The model may, therefore, be used to interpolate clinical data to provide estimated normal tissue complication probabilities for any combination of dose and irradiated volume for the normal tissues and end points considered.

Humans↗
PubMed1991

Histogram reduction method for calculating complication probabilities for three-dimensional treatment planning evaluations.

New tools are needed to help in evaluating 3-D treatment plans because of the large volume of data. One technique which may prove useful is the application of complication probability calculations. A method of calculating complication probabilities for inhomogeneously irradiated normal tissues is presented in this paper. The method uses clinical estimates of tolerance doses for a few discreet conditions of uniform partial organ irradiation, an empirical fit of a continuous function to these data, and a technique (the effective volume method) for transforming nonuniform dose-volume histograms into equivalent uniform histograms. The behavior of the effective volume histogram reduction method for various boundary conditions is reviewed. The use of complication probabilities in evaluating treatment plans is presented, using examples from an NCI 3-D treatment planning contract.

Humans↗
PubMed1991

Numerical scoring of treatment plans.

This is a report on numerical scoring techniques developed for the evaluation of treatment plans as part of a four-institution study of the role of 3-D planning in high energy external beam photon therapy. A formal evaluation process was developed in which plans were assessed by a clinician who displayed dose distributions in transverse, sagittal, coronal, and arbitrary oblique planes, viewed dose-volume histograms which summarized dose distributions to target volumes and the normal tissues of interest, and reviewed dose statistics which characterized the volume dose distribution for each plan. In addition, tumor control probabilities were calculated for each biological target volume and normal tissue complication probabilities were calculated for each normal tissue defined in the agreed-upon protocols. To score a plan, the physician assigned a score for each normal tissue to reflect possible complications; for each target volume two separate scores were assigned, one representing the adequacy of tumor coverage, the second the likelihood of a complication. After scoring each target and normal tissue individually, two summary scores were given, one for target coverage, the second reflecting the impact on all normal tissues. Finally, each plan was given an overall rating (which could include a downgrading of the plan if the treatment was judged to be overly complex).

Humans↗
PubMed1991

Three-dimensional photon treatment planning for carcinoma of the nasopharynx.

The role of 3-D treatment planning for carcinoma of the nasopharynx was assessed in a four institution study. Two patients were worked up and had an extensive number of CT scans on which target volumes and normal tissues were defined. Treatment planning was then performed using state of the art dose planning systems for these patients to assess the value of the new technology. In general, it was demonstrated that multi-field conformal plans could achieve good tumor dose coverage, while at the same time reducing normal tissue doses, compared to standard treatment planning techniques. The role of inhomogeneity corrections, beam energy, and the use of CT vs. simulation films for defining target volumes were also discussed. In addition, techniques to evaluate 3-D plans for the nasopharynx were considered, and some analysis of this problem is presented in this paper.

Adult↗
PubMed1991

Improved dose distributions for 3D conformal boost treatments in carcinoma of the nasopharynx.

This study was designed to demonstrate the feasibility of 3-dimensional (3D) treatment planning in patients with carcinoma of the nasopharynx, and to explore its potential therapeutic advantage over the traditional 2-dimensional (2D) approach in this disease. Qualitative and quantitative comparisons between the two techniques were made for the boost portion of the treatment (19.8 Gy of a total 70.2 Gy treatment schedule) in 10 previously untreated patients and for the entire treatment in 5 patients with locally recurrent disease. The 2D and 3D plans were compared in each patient using dose-volume histograms (DVH's), tumor control probabilities (TCP's), normal tissue complication probabilities (NTCP's), and a new biologic figure of merit that describes the probability of uncomplicated control. Although there was no attempt to optimize the 3D treatment approach by using this method throughout the total treatment course (rather than for the boost only), it was still found that for each of the endpoints examined the 3D approach resulted in improved plans. An average of 22% of the target volume was underdosed at the 95% isodose level with the 2D plans compared to 7% with the 3D plans. The improved treatment planning by 3D increased the mean dose to the tumor volume by an average of 13% over 2D planning. The dose to normal structures such as the mandible and parotid glands was reduced with the 3D plans while the brain stem and spinal cord remained within tolerance limits. The probability of uncomplicated tumor control was increased by an average of 15% with 3D treatment planning compared to the 2D approach. Our findings demonstrate the potential of 3D planning for improving the treatment of carcinoma of the nasopharynx, but prospective studies are required to define the true clinical advantages of this methodology.

Humans↗
PubMed1991

Compensation in three-dimensional non-coplanar treatment planning.

This paper presents a technique for producing uniform dose distributions within the target volume with non-coplanar field arrangements. The method is based upon the principle used for producing homogeneous dose distributions for a pair of fields in two dimensions, namely, that if the isodose distributions for the fields are made parallel to one another, the combined dose distribution will be uniform. For the three-dimensional non-coplanar case, homogeneous target dose distributions are obtained by designing field modifiers which produce a uniform dose distribution on the perpendicular bisector plane for each pair of fields. It is demonstrated that for three non-coplanar fields irradiating a spherical phantom with spherical target volumes, the target dose distribution will be homogeneous for any arbitrary non-coplanar field arrangement. Furthermore, this technique can be extended to any number of fields. Therefore, target dose distributions for non-coplanar plans can be as homogeneous as the coplanar case. An example of the application of the method to the treatment of rectal carcinoma with non-coplanar fields is given. Furthermore, it is demonstrated that the therapeutic ratio is improved over traditional methods for this clinical example.

Humans↗
PubMed1991

The biological basis for conformal three-dimensional radiation therapy.

The recent introduction of new computer technology for treatment planning and computer-driven treatment delivery systems, such as multi-leaf collimators and on-line verification systems, has accelerated the development of 3-dimensional (3-D) radiation therapy as a modality for curative cancer treatment. The goal of 3-D treatment planning is to conform the spatial distribution of the high radiation dose to the shape of the tumor contour while concomitantly decreasing the volume of the surrounding normal tissues receiving high radiation doses. The improved precision of tumor coverage and the exclusion of normal tissues should permit tumor dose escalation and may enhance local tumor control. It has been suggested that any survival gains derived from improvements in local control may be offset by the subsequent appearance of distant metastases arising from micrometastases already present at the time of initial diagnosis. However, clinical and laboratory studies indicate that failure to control the primary tumor at the time of initial treatment significantly increases the incidence of metastatic dissemination. This phenomenon is consistent with the hypothesis that the enhanced mitotic activity associated with the re-growth process of locally recurring primary tumors promotes the multi-step transformation of non-metastatic tumor cells into clonogens with metastatic potential, leading to increased overall rates of metastatic disease. These biologic considerations provide support for the need to focus attention on the identification of more effective therapeutic strategies designed to eradicate the primary local tumor completely at the time of initial therapy and serve as the rationale for clinical studies using 3-D conformal radiation therapy.

Humans↗
PubMed1990

Total body irradiation for bone marrow transplantation: the Memorial Sloan-Kettering Cancer Center experience.

In May 1979, Memorial Sloan-Kettering embarked on a programme of hyperfractionated TBI (HFTBI), 1320 cGy in 11 fractions over 4 days with partial lung shielding (1 HVL), followed by cyclophosphamide (60 mg/kg/d x 2d) for cytoreduction prior to allogeneic bone marrow transplantation (BMT). Anterior and posterior chest wall electron "boosts" were given to the areas blocked (600 cGy in 2 fractions) on the last two days of treatment. Since then, we have treated over 600 patients with HFTBI, the majority for allogeneic BMT. Several modifications have occurred over the years. We have added a "boost" electron dose of 400 cGy to the testes in all male leukemic patients; this reduced testicular relapses from a rate of 14% (4/28) to 0%. In an attempt to increase engraftment of T-depleted BMTs, we added one additional fraction; since our present dose/fraction was also increased to 125 cGy, we now deliver a total dose of 1500 cGy in 12 fractions over 4 days for allogeneic transplants. Tolerance to HFTBI has been excellent relative to the single dose (SD) regimen utilised prior to May, 1979. The incidence of fatal interstitial pneumonitis (IP) decreased from 50% in the SD regimen to 18% after the introduction of HFTBI. In children, the incidence of IP was only 4% with HFTBI. With the introduction of T-depleted marrows, fatal IP in adults has decreased also, e.g. to less than 10% in CML patients. With conventional BMT after HFTBI, relapse at 5 years has been exceedingly low (e.g. in children, 13% for ALL, 2nd remission and 0% for AML, 1st remission) and engraftment has been 100%. With matched T-depleted BMT, rejections have occurred in 15% overall; the incidence of graft failure has not been reduced by the higher dose of HFTBI. Relapses in this setting are equivalent to relapses with conventional BMT for AML, but appear to be increased for ALL. Radiobiological findings related to HFTBI will also be discussed.

Bone Marrow Transplantation↗
PubMed1989

The use of lymphoscintigraphy in treatment planning of primary breast cancer.

A technique is described for the use of lymphoscintigraphy in treatment planning of primary breast patients. During simulation of the treatment fields, the positions of the internal mammary nodes are projected back toward the source onto the patient skin surface and are marked by radio-opaque markers for visualization on films. Exact solutions for the coordinates of these surface projection points are derived. Approximate solutions are also given which are independent of the isocenter location and primarily dependent on the treatment field gantry angle. If a typical couch angle and field size are assumed, the projection points can be calculated for various gantry angles prior to simulation. Generally, a decision can then be made beforehand whether it would be better to use deep tangents or a separate field to treat the internal mammary nodes. During simulation, the surface projection points serve as visual and fluoroscopic guides to field design and optimization. A method is also presented for projecting the internal mammary node positions onto a single transverse patient contour for conventional 2-dimensional treatment planning. By accurately showing the projected location of the node with respect to the field edge, adequate treatment margin can be assured.

Breast Neoplasms↗
PubMed1989

Simulating blocks in treatment planning calculations.

It is difficult to make an accurate calculation of dose distribution incorporating blocks using a ray model. One approach is to simulate the blocking in a treatment planning distribution by using negatively weighted beams. A second is to employ an external contour. The parameters of the negative beam or contour can be adjusted using empirical dosimetric data. This paper discusses the calculation of the dose distributions using negatively weighted beams and external contours, compares them with measurements in and around blocked areas for a range of field sizes, block sizes, and depths of interest in treatment planning applications, for 60Co, 6 MV, and 10 MV beams, and assesses their applicability.

Computer Simulation↗
PubMed1989

Calculation of complication probability factors for non-uniform normal tissue irradiation: the effective volume method.

An estimation of normal tissue complication probability factors is important, particularly for evaluating 3-dimensional treatment plans. A method has been developed to calculate complication probability factors for non-uniformly irradiated normal organs using dose volume histograms and complication probabilities for uniform partial organ irradiation. In the effective volume method each volume element of the histogram is considered independently and subject to a power law dose volume relationship. Thus, a non-uniform dose volume histogram is reduced to a uniform one with an effective volume, and a dose equal to the maximum dose to the organ. The complication probability is then obtained from known complication probabilities for uniform partial organ irradiation. The effective volume histogram transformation method is shown to obey various boundary conditions, and is illustrated by comparing probability calculations for alternative 3-dimensional treatment plans for the pelvis. In addition, the limitations of this histogram reduction method are discussed and compared to other calculational techniques. The use of probability factor calculations in treatment plan evaluation, and their role in numerical scoring is explored.

Humans↗
PubMed1988

Applicator for optimum cobalt-60 primary breast treatments.

A breast applicator has been designed to optimize 3 field breast treatments for 60Co. The device has a six half value layer beam splitting block constructed in two sections. The larger permanently mounted section is sufficient for treating 90% of the patients. Slots are available for mounting cerroband blocks, and any of five brass half field wedges. A magnetically attached front and back-pointer assembly readily breaks away in the event of a collision between pointer and patient. With this design the breast applicator with wedges and blocks has in-field surface doses reduced to that of an open field without accessory devices. The 50-90% dose decrement of the radiation penumbra for the half field block is comparable to that for the field edge of a typical 6 MV X ray unit, although the 50-10% decrement is larger. The average out-of-field dose at the surface is 8% and is 5% at the depth of dose maximum. The combination for this applicator of sharp penumbra and low out-of-field dose leads to reduced lung and opposite breast doses. The latter was confirmed with TLD measurements on 10 patients, and yielded an average opposite breast dose of 230 cGy for a 4600 cGy prescription. Thus, half-field blocking devices do not preclude, as has been stated in the literature, acceptable opposite breast doses. In addition, proper design of these devices can significantly improve the radiation characteristics for primary breast treatments.

Breast Neoplasms↗
PubMed1988

A comprehensive three-dimensional radiation treatment planning system.

A comprehensive software system has been developed to allow 3-dimensional planning of radiation therapy treatments using the extensive anatomical information made available by imaging modalities such as CT and MR. Biological structures of interest and tumor volumes are defined by outlines drawn on a sequence of CT slices. Beam set-ups may then be determined in three dimensions by displaying the structure contours in a beam's eye view, or in two dimensions using a single CT cut. Each beam defined may be shaped by the specification of block aperture contours, and its intensity may be modified with the use of planar compensators. 3D dose calculation algorithms are discussed. To evaluate the calculation results, dose volume histograms are provided, as well as various types of displays in two and three dimensions, including dose on arbitrarily oriented planes, dose on the surface of anatomical objects, and isodose surfaces. Computer generated beam films are also available as an aid in patient set-up verification. These tools, and others, provide the basis for a comprehensive 3D system that can be used throughout the treatment planning process.

Humans↗
PubMed1987

Matchline dosimetry of a three field technique for breast treatment using cobalt or 6 MV X rays.

The matchline dose distribution between the tangential and supraclavicular fields used for treatment of breast cancer was investigated using 60Co and 6 MV X rays. Techniques which allow minimum, moderate, and maximum overlap between the fields as well as a geometric alignment technique were studied. For a given technique, comparable matchline widths and doses were obtained with either machine. Average matchline doses were slightly greater with 6 MV X rays, however, more tissue was irradiated to higher dose levels with 60Co. Among the techniques which do not geometrically align the three fields, doses as high as 150% or as low as 70% were observed depending on the amount of overlap between the fields. Matching the tangents 3.5 cm medial and lateral to the supraclavicular field center yielded average maximum and minimum matchline doses within ten percent of those with geometric alignment techniques. However, these distributions will vary with patient size and matchline length. Geometric alignment techniques offer the advantages of matchline dose uniformity and reproducibility over the patient population with maximum matchline doses of only 110-115%.

Breast Neoplasms↗
PubMed1987

Technique for external beam treatment for mesothelioma.

A combined photon-electron beam treatment for diffuse pleural mesothelioma is discussed in this paper. The technique consists of parallel opposed 10 MV X rays prescribed to 4250 cGy using customized blocks to shield the lung. The pleura is then boosted with electrons to a dose of 3600 cGy. The combination yields a TDF of 74 ret to the pleura. As discussed in an earlier paper, this treatment method when combined with subtotal pleurectomy and I-125 implantation leads to improved survivals with minimal complications. The details of this 3-dimensional radiation treatment method were not described in detail. To improve target coverage and local control, the technique has been modified. CT is now used along with simulation plane films to define the entire pleural surface. The target volume has also been extended from the dome to the base of this diaphragm. These changes have led to improved pleural dose distributions; by blocking the liver or stomach, and boosting the crus of the diaphragm with electrons, there is little added morbidity. As is demonstrated by dose volume histograms, we have been able to deliver 4250 cGy +/- 10% to most of the pleura with 1/3 of the lung parenchyma receiving less than 2100 cGy.

Brachytherapy↗
PubMed1986

Choice of optimum megavoltage for accelerators for photon beam treatment.

Over three decades ago, the development of megavoltage accelerators revolutionized radiation oncology and provided the therapist with photons and electrons of any desired energy. The initial advantages cited for high energy photon therapy, listed below, have proved valid and accelerators have almost totally replaced orthovoltage units. Initially, it appeared that most of these cited advantages should continue to improve with increasing energy, and there has been an impetus for the production of ever higher megavoltage accelerators. Some of these advantages are reviewed in this paper. Also, recent investigations have indicated increasing diffuseness of the photon beam boundary with increasing energy because of lateral transport of electrons. The impact on treatment planning as a function of energy of the increase in volume dose due to the diffuseness of beam boundaries, "build-down" and "rebuild-up" effects in tissues at cavity and inhomogeneity interfaces, bone absorption, and photoneutron production are discussed. Consideration of the behavior of these parameters indicates that optimum photon energies have been achieved and that the impetus for higher megavoltages is unwarranted for most treatment. For many therapeutic applications, there are major advantages of 4 MV to 8 MV photon beams relative to 60Co gamma rays. For large lesions in the abdomen or pelvis there is an advantage to energies above those provided by 15 MV units. The various considerations above are discussed and summarized as a function of lesion site and megavoltage.

Humans↗
PubMed1986

Management of coexisting Hodgkin's disease and pregnancy.

The management of pregnant women with active Hodgkin's disease (H.D.) should be individualized depending on the stage, the presence of infradiaphragmatic involvement, and age of gestation. Seventeen women aged 16-31 years with coexisting H.D. and pregnancy were followed between 1969 and 1982. H.D. was diagnosed during pregnancy in 15 patients and two became pregnant while on treatment. Seven women whose pregnancies were allowed to proceed uninterrupted were irradiated to supradiaphragmatic sites to doses of 1,500-2,000 rad during the second or third trimester; all had full term spontaneous normal deliveries and normal infants. Fetal doses ranged from 2-50 rad. Two patients treated with Vinblastine throughout three pregnancies delivered normal full term infants. Pregnancy was interrupted in six patients at 6-20 weeks of gestation for various reasons. In spite of several months delay in initiation of definitive therapy, the outcome of H.D. was not adversely affected in the majority of uninterrupted pregnancies as evidenced by long term disease-free survivals of 6-11 years in four of seven patients who were irradiated; the children now aged 6-11 years are also alive and reported normal.

Adolescent↗