Waiting patiently.
Explore the source record for details and available documents.
Appointments and Schedules↗
Biomedical subjects
M Goitein
Publications and source records attributed to M Goitein.
Considerations in fractionated proton radiation therapy: clinical potential and results.
Protons have a finite range in tissue and can provide a better concentration of radiation dose in the tumor than conventional X-rays in certain situations. The development of optimized treatment plans for X-rays and protons followed by a comparative evaluation is one method of selecting tumor sites best suited for proton treatment. The preliminary results of comparative treatment planning for base of skull tumors and carcinoma of the prostate are discussed. These comparisons suggest a clinical gain for proton treatment of tumors in these locations. The clinical experience with fractionated proton treatment of several tumor sites is also discussed. The results of high dose proton treatment of chordomas and low grade chondrosarcomas of the base of skull is particularly promising: an actuarial 5-year local control of 78% has been obtained in 50 patients followed for a minimum of 22 months.
Carcinoma↗
Oblique sections need 3-D names also.
Explore the source record for details and available documents.
Humans↗
Fractionated proton radiation therapy of cranial and intracranial tumors.
Since 1973 fractionated proton radiation therapy has been used in the treatment of malignant disease. Protons have favorable physical characteristics that yield dose distributions superior to those of photons in certain clinical situations. As of December 31, 1987, 1,678 patients had been treated. Of these, 110 had chordomas or low-grade chondrosarcomas of the base of skull. The first 68 patients have a minimum follow-up of 17 months. The median dose was 69 Cobalt Gray Equivalent (CGE). (CGE is the dose in proton Gray multiplied by 1.1, which is the relative biological effectiveness for protons relative to 60Cobalt.) The actuarial 5-year local control rate is 82%, and the disease-free survival rate is 76%. Thirteen patients with meningiomas have been treated, following subtotal resection. The median dose was 59.4 CGE. With a median follow-up of 26 months, no patient has had tumor progression. In addition, nine patients with gliomas and 12 with craniopharyngiomas have been treated.
Adolescent↗
Increased efficacy of radiation therapy by use of proton beam.
Proton beam treatment techniques provide a powerful approach to improving dose distribution (decrease treatment volume towards target volume) and hence increasing dose to target with resultant higher tumor control rates and lesser morbity. To achieve these dose distributions in patients requires use of modern imaging techniques, rigid immobilization systems, confirmation of target position vis a vis the proton beam at each treatment session, treatment planning which feature beam's eye view, displays of uncertainty, dose at each anatomic point, boli based on accurate assessment of density along each pixel, etc. Experience at MGH/MEEI/HCL has yielded a disease-free survival of 78% for patients with chordoma/chondrosarcoma of base of skull. Local control is achieved by 98% of patients treated for choroidal melanoma.
Chondrosarcoma↗
Evaluation of volumetric differences through 3-dimensional display of distance of closest approach.
Treatment planning programs offer the ability to view quantitative information on serial CT sections. Many of these programs also offer the ability to view structures of anatomical interest from a beam's-eye view. Such displays may be of wire-frame objects or of shaded surface reconstructions derived from contours drawn in serial CT or MRI sections. Such surface reconstructions are not only shaded to give a 3-dimensional perspective, but can be colored in order to display information about some underlying property of a structure. Color has, for example, been used to demonstrate the distribution of dose on the surface of volumes of interest. We introduce a technique in which color is used to show the spatial differences between volumes of interest by displaying the surface of one volume and encoding in color the distance of closest approach of another volume. Regions in which the two surfaces are within a specified distance are shown in gray; regions in which the first structure lies outside the second are shown in reddish/yellow hues; and regions where the second is outside the first are shown in bluish/green hues with the hue being proportional to the distance apart. Such displays offer insight into anatomical relationships not otherwise easily obtained.
Models, Structural↗
Neurovisual outcome following proton radiation therapy.
From February 1981 to January 1984, 20 patients with a tumor of the upper clivus received proton irradiation at the Harvard Cyclotron Laboratory. For 15 patients with known neurovisual status (including visual acuity, color vision, visual field, and fundus examinations) we obtained a cumulative dose-volume histogram (DVH) of the optic nerves (ON) and the optic chiasm. The prescribed tumor doses ranged from 66.6 to 74.4 Cobalt Gray Equivalent (CGE) with a daily fraction size of 1.8 to 2.1 CGE. CGE is used because modulated protons have an RBE of 1.1 compared to 60Co. The follow-up ranged from 30 to 68 months (median 52). Two patients developed, 10 and 36 months post irradiation, a progressive visual deterioration affecting both eyes. This was attributed to an ON and a chiasm injury in one patient and to bilateral ON injury in the other patient. In the first patient, the dose-volume analysis indicated that approximately half of the ON and of the chiasm had received 65 CGE and 55 CGE, respectively. In the second patient, it indicated that a quarter of the left ON (LON) had received 55 CGE whereas the dose to the right ON (RON) was significantly less. This patient had diabetes mellitus which may be a predisposing factor. From this study, a complication rate of 20% (1/5) is observed when a substantial portion of the ON is taken to 65 CGE, while it doesn't exceed 12.5% (2/16) and 7.5% (1/13) at 55 CGE for the ON and for the chiasm, respectively. This suggests a tolerance dose implying a 10% rate of major complications close to 55 CGE. When a tumor requires a high radiation-dose, the exclusion of these structures at 55 to 60 Gy is recommended.
Adult↗
The risk of enucleation after proton beam irradiation of uveal melanoma.
Enucleation after proton beam irradiation of uveal melanomas occurred in 64 (6.4%) of 994 eyes with a median follow-up time of 2.7 years. The median time between irradiation and enucleation in the 64 enucleated eyes was 13 months. The probability of retaining the eye was 95 and 90%, 2 and 5 years postirradiation, respectively. Three percent of eyes were enucleated during posttreatment year 1, and the yearly rate was 1% by the fourth year. No patient had enucleation later than 5 1/2 years posttreatment. The complication most likely to result in enucleation was neovascular glaucoma although this was frequently managed without enucleation. Other common reasons for enucleation were documented or suspected tumor growth and complete retinal detachment with associated loss of vision. The leading risk factors for enucleation were anterior tumor margin involving the ciliary body, tumor height greater than 8 mm, and proximity of the tumor to the fovea. Based on the presence or absence of these factors, 5-year eye retention rates were 99, 92, and 76% for low-, moderate-, and high-risk groups, respectively. Thus, the probability of eye retention after proton beam irradiation is high even among those at greatest risk of enucleation.
Eye Enucleation↗
Distal penetration of proton beams: the effects of air gaps between compensating bolus and patient.
Explore the source record for details and available documents.
Air↗
Fractionated proton radiation therapy of chordoma and low-grade chondrosarcoma of the base of the skull.
Sixty-eight patients with chordoma or low-grade chondrosarcoma at the base of the skull received fractionated high-dose postoperative radiation delivered with a 160-MeV proton beam. Protons have favorable physical characteristics which allow the delivery of high doses of radiation to these critically located tumors. The methods employed for these treatments are described. These patients have been followed for at least 17 months and for a median of 34 months. The median tumor dose was 69 CGE (cobalt Gy equivalent): CGE is the dose in proton Gy multiplied by 1.1, which is the relative biological effectiveness for protons compared to cobalt-60. The daily dose was 1.8 to 2.1 CGE. For this group the 5-year actuarial local control rate is 82% and disease-free survival rate is 76%. The incidence of treatment-related morbidity has been acceptable.
Adolescent↗
Potential for improvement in radiation therapy.
A successful strategy for improving the efficacy of radiation therapy has been to improve dose distribution, that is, reduce treatment volume toward target volume. This is so as the smaller treatment volume has permitted a higher dose to the target (hence a high tumor control probability) and a lesser volume of non-target tissues being irradiated (consequently a reduced frequency and severity of treatment related morbidity). There are in place several important means for further improvements in dose distributions. These include: (a) 3D graphic reconstruction of the affected part with definition of the position of the tumor vis-a-vis the adjacent normal structures; (b) explicit inclusion in the treatment plan of the uncertainty band around each isodose contour; (c) on-line contrast enhanced visual monitoring of the target tissue during the individual treatment session; (d) gating of treatment so as to reduce the impact of patient motion on the needed treatment volume; (e) use of computer control systems to execute the treatment; and (f) use of treatment methods which achieve a reduced treatment volume. In an examination for sites for which treatment volumes might be decreased by a substantial factor we have compared treatment volumes for radical surgical and radiation therapy. Results are presented for carcinomas of the cervix (Stage IB), breast (Stage II), floor of mouth (Stage II). We describe a system developed here for on-line visual monitoring of the tissues covered by the treatment field. Brief descriptions are given of results of low LET charged particle radiation therapy and of intraoperative electron beam therapy. Also, the program developed here to use computer graphic techniques to display tumor and normal structures and isodose countours with uncertainty bands around each contour is mentioned.
Combined Modality Therapy↗
Endocrine function following high dose proton therapy for tumors of the upper clivus.
The endocrine status of patients receiving proton radiation for tumors of the upper clivus was reviewed to evaluate the effect of high dose treatment on the pituitary gland. The fourteen patients had chordomas or low grade chondrosarcomas and were all treated by the same techniques. The median tumor dose was 69.7 Cobalt Gray Equivalent (CGE) with a range from 66.6 to 74.4 CGE. (CGE is used because modulated protons have an RBE of 1.1 compared to 60Co). The daily fraction size was 1.8-2.1 CGE. The median follow-up time is 48 months, ranging from 30 to 68 months. All treatments were planned using a computerized multi-dimensional system with the position of the pituitary outlined on the planning CT scan. Review of the dose distribution indicated that the dose to the pituitary ranged from 60.5 to 72.3 CGE, with a median of 67.6 CGE. One female patient had decreased thyroid and gonadotropin function at the time of diagnosis and has been on hormone replacement since that time. The other three females were all pre-menopausal at the time of radiotherapy. At this time four patients (3 males and 1 female) have developed endocrine abnormalities 14 to 45 months after irradiation. All four had evidence of hypothyroidism and two have also developed corticotropin deficiency. The three males had decreased testosterone levels; the female patient developed amenorrhea and hyperprolactinemia. All four are asymptomatic with ongoing hormone replacement.
Adolescent↗
Metastasis from uveal melanoma after proton beam irradiation.
The incidence of metastasis and prognostic factors for metastasis in 780 consecutive patients with uveal melanomas treated with proton beam irradiation were evaluated. Metastasis developed in 64 patients (8%). The median time from treatment to the diagnosis of metastasis was 2.1 years (range, 3 months to 7.3 years). The liver was primarily involved in 58 (90%) patients. The 5-year cumulative probability of metastasis developing was 20%. Prognostic factors for metastasis developing were quite comparable to those found for patients treated by enucleation and included largest tumor diameter, involvement of the ciliary body, older age, and extrascleral extension. Surgical localization, tumor height, and elevated liver enzymes before treatment were not important factors in the development of metastasis.
Adolescent↗
The effect of the respiratory cycle on mediastinal and lung dimensions in Hodgkin's disease. Implications for radiotherapy gated to respiration.
Changes in mediastinal and lung dimensions during respiration were studied to assess the potential of radiotherapy gated to respiration to minimize normal tissue irradiation. Twelve patients with mediastinal Hodgkin's disease were assessed using chest radiographs and thoracic computed tomography (CT) scans both during quiet breathing and at maximum inspiration in the standing, supine, and prone positions. A simple measure of the bulk of mediastinal disease, the ratio of the width of mediastinal mass to thoracic diameter, was determined from posteroanterior (PA) chest radiographs. The volumes of mediastinum, irradiated and protected lung if anteroposterior (AP) and PA mantle fields were used were determined from sequential thoracic CT scans and three-dimensional treatment planning and compared at quiet breathing and deep inspiration. The mediastinal width to thoracic diameter ratio decreased from quiet breathing to deep inspiration an average of 3%, 9%, and 11% for the standing, supine, and prone positions, respectively. Lung volumes as measured from the thoracic CT scans showed that on average, 8% more lung was protected at deep inspiration than at quiet breathing, independent of treatment position. The maximum increase in the percentage of protected lung from quiet breathing to deep inspiration was seen in patients with extensive mediastinal adenopathy suggesting that radiotherapy gated to respiration may be most advantageous in the subset of patients.
Hodgkin Disease↗
Uveal melanomas near the optic disc or fovea. Visual results after proton beam irradiation.
Proximity to the disc and fovea is a risk factor for visual loss after proton beam irradiation of uveal melanomas. Of 562 eyes treated over a 10-year period with pretreatment visual acuity of 20/200 or better, 363 (64.6%) contained tumors within 2 disc diameters (DD) of the disc or fovea. Rates of visual loss after treatment to worse than 20/200 and causes of visual decline were evaluated using Kaplan-Meier analysis. Cumulative rates of visual loss among subjects with tumors near the disc or fovea were 33 and 47% 1 and 2 years after treatment compared to 17 and 28%, respectively, for subjects with tumors located farther from both structures. The leading cause of visual loss in the first year among eyes with tumors near the disc or fovea was retinal detachment. Controlling for other predictors of visual loss to worse than 20/200, location near the disc or fovea was independently related to visual loss primarily due to retinal detachment, cataract, and radiation retinopathy. Despite the unfavorable location of these tumors, over half of patients with 20/200 or better pretreatment visual acuity had useful vision 2 years after treatment.
Cataract↗
Long-term results of proton beam irradiated uveal melanomas.
The first 128 consecutive patients with uveal melanomas treated with proton beam irradiation were studied in order to evaluate survival and visual acuity status of patients with relatively long-term follow-up. The median follow-up was 5.4 years, and no patient was lost to follow-up. All tumors showed regression. The most recent visual acuity was 20/40 or better in 35% and 20/100 or better in 58%. Eight eyes were enucleated because of complications. Metastasis developed in 26 patients (20.5%) from 3 months to 7 years after treatment. Results indicate that proton irradiation is quite successful for achieving local control of uveal melanomas. A large proportion of the treated eyes maintained useful vision. Five-year follow-up data indicate that proton irradiation has no deleterious effect on the likelihood of the development of metastasis.
Eye Diseases↗
[Fractionated proton radiotherapy].
Investigations in proton beam therapy of cancer patients have been initiated at the Cyclotron Laboratory, Harvard University, Cambridge, USA, since 1974 using a proton beam with the energy of 160 MeV for fractionated irradiation of uveal melanoma (899 cases), chordoma and chondrosarcoma of the base of the skull (96), sarcoma of the soft tissues and bones (79), prostatic cancer, head and neck tumors, etc. (altogether 1331 patients had been irradiated by June, 1986). To stop a beam in the target computer-assisted three-dimensional design and heterogeneity calculations were performed; computed compensatory boles were produced. Proton beam therapy is used alone or in combination with proton beam irradiation, routine radiotherapy. Areas of particular interest are ocular melanoma, chordoma and chondrosarcoma of the base of the skull, paraspinal sarcomas. Investigations in the field of proton beam therapy of malignant meningioma, metastases to the paraaortic lymph nodes hold promise.
Humans↗