An interactive beam-weight optimization tool for three-dimensional radiotherapy treatment planning

A computer software tool has been developed to aid the treatment planner in selecting beam weights for three-dimensional radiotherapy treatment planning. The program consists of a feasibility search algorithm embedded in an interactive, user-friendly driving program. The feasibility search algorithm is based on the iterative relaxation algorithm of Cimmino [La Ricerca Scientifica, Vol. I, pp. 326-333 (1938)] as applied to the radiotherapy inverse problem by Altschuler et al. [Med. Phys. 13, 590 (1986)]. Relative importances of structures based upon clinical considerations can be incorporated into the algorithm. In order to speed convergence, the relaxation parameter is made to vary, with its value based upon a measure of deviation from feasibility. The interactive driving program is designed so that the treatment planner can make reasonable judgments regarding the acceptability of a plan in the event that the dose constraints yield no feasible solution. An example of the use of this program applied to a problem in three-dimensional radiotherapy treatment planning is illustrated.

Results and implications of high-resolution surface dosimetry of ruthenium-106 eye applicators

The dosimetry of 106Ru/106Rh beta-emitting eye applicators is still inadequate. Manufacturer's specifications of absolute dose rates are loaded with a +/- 30% error, and the relative distribution of activity on the surface is measured on a few points only, using a 3-mm plastic scintillation probe. While reducing the absolute error of dose rate measurements to +/- 15% by a method published earlier, we now present a phantom using small thermoluminescent dosimetry crystals for refined assessment of its distribution over the surface. Evaluation of two applicators revealed a 50% increase in activity in the midperiphery in one and a steep falloff of activity 1 mm within the margin of both specimens. The method and findings are demonstrated in detail and compared to those reported by other authors.

Radiation retinopathy: electron microscopy of retina and optic nerve

A 4 1/2 year old female was treated for embryonal rhabdomyosarcoma of the left orbit in 1975 with radiation (59.5 Gy in 5 weeks), followed by chemotherapy. An electroretinogram (ERG) in March, 1988 revealed cone responses 3% of normal and no rod responses in the left eye, and normal responses in the right eye. The eye was enucleated in April 1988. In the fovea no choroidocapillaris was seen at the intact Bruch's membrane, and the pigment epithelium was preserved only in small patches. No photoreceptor cells were seen in the areas devoid of pigment epithelial cells. The parafoveal and peripheral (30 degrees eccentricity) retina was better preserved. The thickness of the layer of rods and cones and of Henle's fiber layer was reduced. Very few outer segments were present. Macrophages had invaded the retinal tissue in moderate numbers. The retinal vessels were ensheathed by several layers of collagen fibrils. The spatial densities of pigment epithelial, cone, rod, and bipolar cells had been reduced. The optic nerve contained a total number of 1,022,000 nerve fibers.

Eye metastasis from carcinoma of the breast: diagnosis, radiation treatment and results

The experience at the Gershenson Radiation Oncology Center of 32 cases of metastases to the eye or orbit from breast cancer are presented with a review of the literature. The 32 patients were referred for radiation therapy in the period of 1980-1991. Eighteen patients had metastasis to the choroid, 2 patients had involvement of other parts of the eye (anterior chamber +/- choroid), and 11 patients had orbital metastasis. In one patient, the diffuse nature of the disease prevents subsite assignment. Ten of the patients with eye metastases also had brain or meningeal metastases (8 patients concurrent with eye metastases). Four of the 32 patients had bilateral choroidal metastases. A complete course of radiation therapy was delivered to 28 patients, one patient was not treated and 3 patients received only partial treatment because of general deterioration due to other widespread metastases from breast cancer. Of 21 evaluable patients, 15 had definite improvement. There was no progression of the eye metastases in the other 6 patients. The rest (7 patients) were lost to detailed follow-up of the response of the eye metastases. Four patients are still alive without any severe long-term side-effects. The diagnosis, treatment and outcome is presented with a review of the literature. The importance of emergency treatment for rapidly progressing lesions is stressed as well as the need for detailed treatment planning, careful delivery of daily treatments with a high degree of reproducibility and precision to prevent possible damage to sensitive normal structures.

Post-irradiation leiomyosarcoma of the maxilla

Primary malignant smooth muscle tumours of the maxilla are extremely rare. A case of leiomyosarcoma of the maxilla associated with previous irradiation is presented. The aetiology, pathology and clinical aspects of this tumour are reviewed.

Combined localized current field hyperthermia and irradiation for intraocular tumors

Ten patients with large melanomas and one patient with recurrent retinoblastoma were treated with combined localized current field (LCF) hyperthermia and iodine 125 irradiation delivered by episcleral plaque. Tumors were heated to 43 degrees to 45 degrees C for 28 to 45 minutes. Localized current field hyperthermia when combined with irradiation appeared to induce rapid tumor necrosis. One eye enucleated 17 hours after treatment showed only focal necrosis of the melanoma, while another eye demonstrated extensive necrosis 60 hours after treatment. In all remaining eyes, tumor regression occurred within the first month of treatment. Complications included cataract formation in six eyes, hemorrhagic retinal detachment in five eyes, and phthisis in two eyes. Complications from combined therapy of large intraocular tumors in this series appeared to result from the rapid necrosis of the tumor and secondary intraocular inflammation. Intraocular temperature dosimetry measurements demonstrated a temperature gradient of not more than -0.23 degrees C/mm-1 per axial millimeter from the episcleral plaque surface to the apex of the tumor. The authors believe that LCF hyperthermia could be a suitable means of application of hyperthermia in patients with intraocular tumors if further modifications were performed to reduce ocular complications.

Leiomyosarcoma after retinoblastoma radiotherapy

The CT and MR appearance of leiomyosarcoma in the left orbit in a 15-year-old girl is presented. This tumor developed after successful radiation therapy for bilateral retinoblastoma.

Second non-ocular tumours in survivors of bilateral retinoblastoma. A 30-year follow-up

The authors have reviewed a series of 80 patients treated at the Curie Institute before 1965 for bilateral retinoblastoma. They present their cases of second non-ocular tumours in these patients and discuss their results and the possible factors influencing the percentage of second tumours in these patients.

Xenon arch photocoagulator used for transpupillary hyperthermia

The technique of near-infrared irradiation to obtain tumour necrosis in experimental pigmented melanomas is described. The xenon arch photocoagulator was modified and adapted for hyperthermia treatment. The adaptations included: filtering the light and changing the electronics, the aiming beam and the diameter of the beam.

Cobalt60 plaques in recurrent retinoblastoma

Cobalt60 plaque irradiation is one treatment option for patients with recurrent retinoblastoma following conventional external beam irradiation (ERT). Tumorocidal doses can be delivered without excessive risk of normal tissue injury. In patients not considered candidates for xenon arc or cryotherapy, 60Co is an alternative to enucleation. Between 1968 and 1987, 85 patients were treated with 60Co plaques, 72 of whom had failed prior ERT. Age at diagnosis ranged from 1 week to 4 years. There are 37 males and 35 females. Seventy-one patients had bilateral disease and one had unilateral. Three patients had both eyes plaqued. Prior ERT ranged from 30 to 70 Gy (mean 4200 Gy). Time from initial therapy to failure ranged from 13 to 60 months. Cobalt plaques of 10 mm, 15 mm, or 10 x 15 mm were used depending on tumor size and location. Dose prescribed to the apex of the tumor ranged from 30 to 50 Gy (median 40 Gy) given over 3 to 8 days. Twelve patients had two plaque applications; three patients had three plaque applications. All patients were followed with routine ophthalmoscopic examinations. Follow-up ranged from 2 to 22 years (mean 8.7). Seven patients died of metastatic disease; 10 patients developed non-ocular second tumors. Thirty patients required enucleation. Twenty-two patients had clear tumor progression, two patients had radiation complications, and six patients had a combination of tumor growth and complications. Cobalt60 can salvage eyes in retinoblastoma patients failing ERT. Currently, we are using I125 in an attempt to spare normal ocular tissue and reduce subsequent complications.

Long-term treatment effects in patients with bilateral retinoblastoma: ocular and mid-facial findings

A total of 99 patients with bilateral retinoblastoma who had been treated between 1965 and 1982 were reexamined in April 1988 to study the late effects of treatment. Their median age at the follow-up visit in 1988 was 16 years (range, 6-27 years), and the median follow-up was 15 years (range, 6-26 years). All patients underwent a full eye examination, morphometric measurements of the mid-face and genetic counselling. Each eye or orbit and the corresponding side of the patient's mid-face were evaluated separately, resulting in 198 data sets from 99 individuals. Subjects were divided into four treatment groups according to whether photo- and cryo-coagulation, enucleation, radiation therapy or various combinations thereof were used. In all, 81 eyes had a visual acuity of greater than 0.4 (in 23 of these, however, only with low-vision aids). Within a dose range of 36-51 Gy, the location of the tumor (36%) or cataract (15%) were the main factors responsible for poor visual acuity, whereas radiation retinopathy and/or optic neuropathy occurred in only three cases. Cataracts were more frequently observed following orthovoltage as compared with megavoltage therapy (P = 0.012). A total of 72 eyes had been enucleated and had not received radiation therapy at any time. Cosmetic results (as measured by several parameters) in these cases were significantly better then those in 28 subjects who underwent combined radiation therapy and enucleation. As defined by various subjective as well as objective findings, mid-facial hypoplasia occurred significantly more often following orthovoltage as compared with megavoltage therapy.

Recurrent and new tumours during conservative treatment of bilateral retinoblastoma

Conservative treatment of retinoblastoma is a combination of different therapeutic modalities: radiotherapy, photocoagulation, cryocoagulation, chemotherapy. The choice of the most suitable treatment depends on the stage of the disease. The evaluation of the regression and quiescence of tumoral foci after radiotherapy, Xenon photocoagulation or cryocoagulation is based on a purely subjective examination of the ophthalmoscopic aspects which are common to various types of treatment. Frequently, degenerative changes of the tumour mass are difficult to differentiate from actual recurrence. Recurrences generally start at the edge of the scar or within the scar, while new retinal tumours are observed far from the original tumour, sometimes near the ora serrata. The authors discuss the regression patterns and the ophthalmoscopic and clinical aspects of recurrent and new tumours and report their personal experience on the therapeutic approach.

Retinoblastoma. The long-term appearance of radiated intraocular tumors

A retrospective analysis of 50 patients with retinoblastoma was undertaken to determine the appearance of intraocular retinoblastoma that had received external beam radiation a minimum of 10 years previously. Of the 91 tumors found in 59 eyes, 76 (84%) continued to be ophthalmoscopically visible after 10 years. The most common ophthalmoscopic appearance was a Type III regression pattern. The type of radiation regression pattern correlated with the pretreatment volume of the tumor. The largest tumors (mean, 10.0 disc diameter [dd]) became Type I regression patterns, whereas the smallest tumors (mean, 1.0 dd) completely disappeared. This represents the first long-term follow-up of the intraocular status of radiated retinoblastoma.

[Ocular melanocytosis, oculodermal melanocytosis and choroid melanomas]

Among 837 cases of choroidal melanomas treated conservatively, 22 cases (2.69%) presented an ocular or oculodermal melanocytosis. This incidence is compared with the data of the literature. The role of melanocytosis on tumors' parameters and vital prognosis is studied.

Dosimetry and physical treatment planning for iodine eye plaque therapy

The dosimetry of eye plaques loaded with iodine-125 seeds (type 6702) was performed by means of computer calculations and measurements with thermoluminescent dosimeters (TLD). Measurements of the depth dose distribution (2-25.5 mm) along the transverse axis of a single seed were performed in water equivalent phantom material. The transverse axis attenuation and geometry factor F(r) was obtained by applying a least squares fit to the measured data. Based on the resulting radial dose function, a computer program was developed which calculates dose distributions within the eye for arbitrary loading and placement of the eye plaque. The computational results were verified by TLD measurements in an eye phantom.

Incidence and management of secondary malignancies in patients with retinoblastoma and Ewing's sarcoma

Childhood cancer survivors at highest risk of developing a secondary malignancy are those with hereditary retinoblastoma. The majority of such secondary cancers will be sarcomas, most commonly of bone. One-third of these occur outside a typical radiation field, commonly in an extremity. Bone sarcoma is also the most commonly reported secondary cancer to develop among survivors of Ewing's sarcoma. In this group, radiation doses greater than 60 Gy as well as alkylating agent chemotherapy have been identified as contributors to the increased risk. The prognosis for patients with a secondary sarcoma has been poor, with few cures reported to date. However, an aggressive, combined modality approach, including radical resection, postoperative radiation, and adjuvant chemotherapy, may improve the survival rate.

[Oculocerebral malignant non-Hodgkin lymphoma. A report of 5 cases]

Five patients, age 35 to 77, with histologically proven malignent ocular non-Hodgkin's lymphoma (previously known as reticulum cell sarkoma) are presented. The clinical ocular findings (vitreous infiltrates, retinal infiltrates, anterior uveitis) were initially misinterpreted as "panuveitis". The usual antiinflammatory therapie a temporary diminution of the "uveitis" could be observed. Four cases showed a histologically proven CNS involvement. All the patients (except the one in whom the correct diagnosis was made post mortem) received cerebral radiation therapie, including the eyes. Under the radiation therapy the ocular findings disappeared within a few weeks. The longtime prognosis for the eye and quoad vitam is unfortunately not promissing.

Local control and complications after radiation therapy for primary orbital lymphoma: a case for low-dose treatment

Orbital involvement at the time of initial presentation is unusual in non-Hodgkin's lymphoma. In an effort to identify potential ways of improving the radiotherapeutic management of this disease, the records of 22 patients were reviewed retrospectively. All had biopsy-proven orbital non-Hodgkin's lymphoma, and the minimal, median, and maximal durations of follow-up in surviving patients were 4.8 years, 7.0 years, and 17.4 years, respectively. Permanent local control was achieved in 21 of the 22 patients (96%). Complications were scored according to a grading scheme in which grade 1 was the least significant complication and grade 4 was blindness as a result of radiation therapy. Of the 12 patients who received a radiation dose less than 35 Gy, 6 developed a grade 1 or grade 2 complication. Of the 10 patients treated with greater than or equal to 35 Gy, 6 experienced a complication, 1 of whom had a grade 4 complication resulting in blindness and another who developed a severe keratitis, which was scored as a grade 3 complication resulting in decreased visual acuity. At last follow-up, 10 patients were alive at 4.8 to 17.4 years after completion of radiation therapy, 4 had died of intercurrent disease at 3 months to 10.6 years, and 8 had died of disease at 3 months to 15.8 years. Actuarial survival for the entire group was 75% at 5 years and 48% at 10 years. Survival in patients with Stage I AE disease (lymphoma confined to orbit) at presentation was 87% at 5 years and 50% at 10 years, and survival in patients with Stage II A through Stage IV disease was 36% at 5 years and at 10 years. Primary orbital lymphoma is an indolent disease characterized by prolonged survival after radiation therapy. Excellent local control can be achieved with radiation doses of 20 Gy to 35 Gy. Higher doses may result in an increased risk of complications.

Paediatric haemangiomas: the role of radiotherapy

Radiotherapy currently maintains an occasional place in the therapy of complicated haemangiomas of childhood. Eight such childhood benign lesions have been so treated at St Bartholomew's Hospital in the last 10 years. The case histories are presented before being discussed in the context of other therapies available (no treatment, steroids, embolism and surgery), radiation technique used and radiation dose prescription advised.

Radiation regression patterns in treated retinoblastoma: 7 to 21 years later

A retrospective review of cases on file at the Ophthalmic Oncology Center of The New York Hospital-Cornell Medical Center, New York was performed in order to examine the appearance of radiation regression patterns 7 or more years after successful treatment of retinoblastoma with external beam radiotherapy. Forty-eight patients were found to have 89 tumors in 57 eyes which were treated solely with external beam radiation; they were followed for a minimum of 7 years and had sufficient information available for analysis. All but five of the patients had bilateral retinoblastoma. Seventy-four of the 89 tumors continued to be ophthalmoscopically visible after 7 or more years. Taking into account those that did change between the time of first evaluation (usually at the completion of treatment) and final evaluation (7 or more years after treatment), the number of Type I regressions increased by 10.1%, Type IIs decreased by 19.1%, Type IIIs fell by 7.8%, Type IVs rose by 10.1%, and the number of tumors that disappeared increased by 6.8%. Type II remained the most common regression throughout the follow-up. The regression with the greatest potential for change was the Type II regression. The pretreatment volume of the tumor correlated with long-term radiation regression patterns. The smallest tumors (mean size 1.1 dd [disc diameter] or less in size) completely disappeared, while the largest (mean 9.9 dd) became Type I regressions.

The narrow proton beam therapy unit at the the Svedberg Laboratory in Uppsala

The synchrocyclotron at the The Svedberg Laboratory (TSL) in Uppsala is now reconstructed and can presently operate with fixed frequency and proton energies up to 100 MeV. A first treatment room with a narrow proton beam unit for therapy of eye tumours is now in operation. Therapy of eye melanomas started in April, 1989 and during 1989 and 1990, 19 patients were treated with 72 MeV protons. The narrow beam unit provides a fixed horizontal beam and the patient is treated in a seated position. The present paper describes mainly the technical aspects of the unit which so far has been used only for eye melanomas. In the future, modifications of the unit will allow therapy of intracranial targets when higher proton energies are available. In its final form, the proton therapy facility at TSL will harbour a second treatment unit. Here a rotating gantry for 200 MeV protons will provide a broad beam, which will enable treatment of tumours located anywhere in the body.

Removal of radiation-induced cataracts in patients treated for retinoblastoma

Experience with removal of radiation-induced cataract in patients treated for retinoblastoma is limited. We retrospectively reviewed the records of 38 patients with retinoblastoma (42 eyes) who underwent removal of radiation-induced cataract from 1973 to 1989. Nineteen eyes (45%) without macular tumors or severe radiation complications had final visual acuities in the range of 20/20 to 20/50. One eye (2.4%) developed a rhegmatogenous retinal detachment and four eyes (9.5%) were noted to have amblyopia after cataract removal. Three eyes (7%) developed retinoblastoma recurrence, one with extension of retinoblastoma into the subconjunctival space through the previous sclerotomy. Exenteration was performed and the patient was alive after 8 years. Cataract removal can be visually beneficial in selected patients with radiation-induced cataracts.

Experimental boron neutron capture therapy for melanoma: systemic delivery of boron to melanotic and amelanotic melanoma

The boron-containing melanin precursor analogue p-boronophenylalanine (BPA) has previously been shown to selectively deliver boron to pigmented murine melanomas when administered in a single intragastric dose. If boron neutron capture therapy is to become a clinically useful method of radiation therapy for human malignant melanoma, the boron carrier must be capable of delivering useful amounts of boron to remote tumor sites (metastases) and to poorly pigmented melanomas. We have now determined the ability of BPA to accumulate in several nonpigmented melanoma models including human melanoma xenografts in nude mice. The absolute amount of boron in the nonpigmented melanomas was about 50% of that observed in the pigmented counterparts but was still selectively concentrated in the tumor relative to normal tissues in amounts sufficient for effective neutron capture therapy. Single intragastric doses of BPA resulted in selective localization of boron in the amelanotic Greene melanoma carried in the anterior chamber of the rabbit eye and in a pigmented murine melanoma growing in the lungs. The ratio of the boron concentration in these tumors to the boron concentration in the immediately adjacent normal tissue was in the range of 3:1 to 4:1. These distribution studies support the proposal that boron neutron capture therapy may be useful as a regional therapy for malignant melanoma.

Optimization of 125I ophthalmic plaque brachytherapy

Episcleral plaques containing 125I sources are often used in the treatment of ocular melanoma. Within four years post-treatment, however, the majority of patients experience some visual loss due to radiation retinopathy. The high incidence of late complications suggests that careful treatment optimization may lead to improved outcome. The goal of optimization would be to reduce the magnitude of vision-limiting complications without compromising tumor control. We have developed a three-dimensional computer model for ophthalmic plaque therapy which permits us to explore the potential of various optimization strategies. One simple strategy which shows promise is to maximize the ratio of dose to the tumor apex (T) compared to dose to the macula (M). By modifying the parameters of source location, activity distribution, source orientation, and shielding we find that the calculated T:M ratio can be varied by a factor of 2 for a common plaque design and posterior tumor location. Margins and dose to the tumor volume remain essentially unchanged.