Veterinary Intern Program for Entrustable Professional Activities Skills, a.k.a. Intern Boot Camp

The University of Tennessee College of Veterinary Medicine (UTCVM) Department of Large Animal Clinical Sciences has developed an intensive training program that all large animal veterinary interns are required to complete at the onset of their internship year. This program was designed to establish a uniform approach to entrustable professional activity (EPA) skills deemed essential by the large animal faculty. These EPA skills emphasize the clinical approaches and skills that interns should understand and demonstrate competency in early in their internship year. The EPA program, completed over 4 consecutive days, was coined the "Intern Boot Camp" and structured to fuse case-based lecture discussions and hands-on wet labs designed to develop or improve skills and techniques. At the conclusion of the boot camp, participants were given an evaluation survey to provide feedback on the program. The results were overwhelmingly positive, with 90% of the participants giving the program a rating of 5 on a scale ranging from 1 (poor opinion or experience) to 5 (excellent opinion or experience). Nearly 95% of participants stated that they felt more prepared for their internship year after attending the boot camp, and 100% of the participants indicated that they would recommend this program to future candidates. Given the positive outcomes over the past 4 years, the implementation of the Veterinary Intern Entrustable Professional Activities program (Intern Boot Camp) is considered a valuable component of the veterinary intern training program and could readily be adapted to other programs.

Expression of growth hormone receptor in the human brain

This study was designed to investigate the presence of growth hormone receptor (GHR) expression in the human brain tissue, both normal and tumoral, as well as in the human glioblastoma cell line U87MG. Reverse transcription-polymerase chain reaction revealed the presence of GHR mRNA in all brain samples investigated and in U87MG cells. GHR immunoreactivity was also detected in this cell line using both immunocytochemistry and western blotting. All together, our data demonstrate the existence of GHR expression within the central nervous system (CNS), thus supporting a possible role for GH in the CNS physiology.

15 years experience with helium ion radiotherapy for uveal melanoma

PURPOSE

To review the long-term experience of helium ion therapy as a therapeutic alternative to enucleation for uveal melanoma, particularly with respect to survival, local control, and morbidity.

METHODS AND MATERIALS

347 patients with uveal melanoma were treated with helium ion RT from 1978-1992. A nonrandomized dose-searching study was undertaken, with doses progressively reduced from 80 GyE in five fractions to 48 GyE in four fractions, given in 3-15 days, mean of 7 days.

RESULTS

Local control was achieved in 96% of patients, with no difference in the rate of local control being seen at 80, 70, 60, or 50 GyE in five fractions. At the lowest dose level of 48 GyE in four fractions, the local control rate fell to 87%. Fifteen of 347 patients (4%) had local regrowth in the eye requiring enucleation (12 patients), laser (1 patient) or reirradiation (2 patients). The time of appearance of local regrowth ranged from 4 months to 5 years posttreatment, with 85% occurring within 3 years. Of the 347 patients, 208 are alive as of May 1, 1997. The median follow up of all patients is 8.5 years, range 1-17 years. Kaplan-Maier (K-M) survival is 80% at 5 years, 76% at 10 years, and 72% at 15 years posttreatment. Patients with tumors not involving the ciliary body have a 15-year K-M survival of 80%. The results for patients whose tumors involved the ciliary body are poor, with a 15-year K-M survival of 43%. Seventy-five percent of patients with tumors at least 3.0 mm from the fovea and optic nerve, and initial ultrasound height less than 6.0 mm, retained vision of 20/200 or better posttreatment. Patients with tumors larger than 6 mm in thickness, or with tumors lying close to the optic nerve or fovea, have a reduced chance of retaining useful vision. The enucleation rate is 19%, 3% for local failure and 16% because of complications of the helium RT, particularly neovascular glaucoma, which occurred in 35% of patients.

CONCLUSIONS

Local control and retention of the eye are excellent. Complications of therapy reduce vision and eye preservation. Twenty-four percent of patients manifested distant metastases 6 to 146 months posttreatment, mean of 43 months, median of 36 months. Late-appearing distant metastases do not appear to be caused by persistent tumor in the eye. The risk of metastases is high for patients with tumors greater than 7 mm in initial ultrasound height (37%), anterior tumors involving the ciliary body (47%), and in those with local failure (53%). Patients with tumors not involving the ciliary body and initial dimensions less than 10 mm had only an 8% chance of death from melanoma. A search for effective adjuvant therapy is needed for patients at high risk of metastases (large tumors, ciliary body involved, local regrowth in eye).

Anterior segment sparing to reduce charged particle radiotherapy complications in uveal melanoma

PURPOSE

The purpose of this investigation is to delineate the risk factors in the development of neovascular glaucoma (NVG) after helium-ion irradiation of uveal melanoma patients and to propose treatment technique that may reduce this risk.

METHODS AND MATERIALS

347 uveal melanoma patients were treated with helium-ions using a single-port treatment technique. Using univariate and multivariate statistics, the NVG complication rate was analyzed according to the percent of anterior chamber in the radiation field, tumor size, tumor location, sex, age, dose, and other risk factors. Several University of California San Francisco-Lawrence Berkeley National Laboratory (LBNL) patients in each size category (medium, large, and extralarge) were retrospectively replanned using two ports instead of a single port. By using appropriate polar and azimuthal gaze angles or by treating patients with two ports, the maximum dose to the anterior segment of the eye can often be reduced. Although a larger volume of anterior chamber may receive a lower dose by using two ports than a single port treatment. We hypothesize that this could reduce the level of complications that result from the irradiation of the anterior chamber of the eye. Dose-volume histograms were calculated for the lens, and compared for the single and two-port techniques.

RESULTS

NVG developed in 121 (35%) patients. The risk of NVG peaked between 1 and 2.5 years posttreatment. By univariate and multivariate analysis, the percent of lens in the field was strongly correlated with the development of NVG. Other contributing factors were tumor height, history of diabetes, and vitreous hemorrhage. Dose-volume histogram analysis of single-port vs. two-port techniques demonstrate that for some patients in the medium and large category tumor groups, a significant decrease in dose to the structures in the anterior segment of the eye could have been achieved with the use of two ports.

CONCLUSION

The development of NVG after helium-ion irradiation is correlated to the amount of lens, anterior chamber in the treatment field, tumor height, proximity to the fovea, history of diabetes, and the development of vitreous hemorrhage. Although the influence of the higher LET deposition of helium-ions is unclear, this study suggests that by reducing the dose to the anterior segment of the eye may reduce the NVG complications. Based on this retrospective analysis of LBNL patients, we have implemented techniques to reduce the amount of the anterior segment receiving a high dose in our new series of patients treated with protons using the cyclotron at the UC Davis Crocker Nuclear Laboratory (CNL).

Neon heavy charged particle radiotherapy of glioblastoma of the brain

PURPOSE

High-linear energy transfer (LET) radiation beams have potential applications in the treatment of glioblastoma, but have not yet demonstrated significant improvement in results. However, some patients have had local control of glioblastoma with high-LET irradiations such as neutrons and heavy charged particles.

METHODS AND MATERIALS

In this collaborative study, 15 patients were entered into a randomized protocol comparing two dose levels of 20 and 25 Gy in 4 weeks of neon ion irradiation. This trial was intended to determine the optimal neon dose in terms of survival and effects of radiation.

RESULTS

Fourteen patients were evaluable with no significant differences in median survival (13 and 14 months; p = NS) or median time to failure (7 and 9 months; p = NS) between the two dose arms. Three patients died of nontumor-related causes, of whom one (who died 19 months posttreatment) had autopsy confirmation of no tumor on pathological exam. The other two patients had stable magnetic resonance imaging scans at 6 and 22 months posttreatment.

CONCLUSION

Although the results did not demonstrate the optimal high-LET dose level, there is an intriguing effect in that two patients had control of glioblastoma until death at 19 and 22 months. This suggests that better conformation of the high-LET dose to the tumor with neutron capture therapy or dynamic conformal heavy charged particle therapy might control glioblastoma while minimizing brain damage from radiation.

[Dentists in 1810]

Buenos Aires way of life at the ending of 18th and beginning of 19th centuries, when this city was the so called "Gran Aldea" (big small village), is here depicted and so its costumes are, as well as beginnings of the activities of organization and regulation for people dedicates to practise professions related to Health Sciences. The First dentists who acted in this environment are also recalled.

Results of heavy ion radiotherapy

The potential of heavy ion therapy for clinical use in cancer therapy stems from the biological parameters of heavy charged particles and their precise dose localization. Biologically, carbon, neon, and other heavy ion beams (up to about silicon) are clinically useful in overcoming the radioresistance of hypoxic tumors, thus increasing the biological effectiveness relative to low linear energy transfer x-ray or electron beams. Cells irradiated by heavy ions show less variation in cell-cycle-related radiosensitivity and decreased repair of radiation injury. The physical parameters of these heavy charged particles allow precise delivery of high doses to tumors while minimizing irradiation of normal tissues. Clinical use requires a close interaction between radiation oncologists, medical physicists, accelerator physicists, engineers, computer scientists, and radiation biologists.

Helium-ion-induced human cataractogenesis

Retrospective and ongoing analyses of clinical records from 347 primary intraocular melanoma patients treated with helium ions at LBL will allow examination of the exposure-response data for human cataract; which is a complication of the therapy from incidental exposure of the lens. Direct particle beam traversal of at least a portion of the lens usually is unavoidable in treatment of posterior intraocular tumors. The precise treatment planned for each patient permits quantitative assessment of the lenticular dose and its radiation quality. We are reporting our preliminary results on the development of helium-ion-induced lens opacifications and cataracts in 54 of these patients who had 10% or less of their lens in the treatment field. We believe these studies will be relevant to estimating the human risk for cataract in space flight.

Experience in charged particle irradiation of tumors of the skull base: 1977-1992

PURPOSE

To review the experience at University of California Lawrence Berkeley Laboratory in using charged particles to irradiate primary neoplasms of the skull base and those extending to the skull base from the nasopharynx and paranasal sinuses.

METHODS AND MATERIALS

During the period from 1977 to 1992, 223 patients were irradiated with charged particles at the Lawrence Berkeley Laboratory for tumors either arising in or extending to the skull base, of whom 48 (22%) had recurrent lesions, either post previous surgery or radiotherapy. One hundred twenty-six patients had lesions arising in the cranial base, mostly chordoma (53), chondrosarcoma (27), paraclival meningioma (27) with 19 patients having other histologies such as osteosarcoma or neurofibrosarcoma. There were also 31 patients with primary or recurrent squamous carcinoma of the nasopharynx extending to the skull base, 44 patients with major or minor salivary gland tumors, mostly adenocarcinoma, and 22 patients with squamous carcinoma of the paranasal sinuses, all with cranial base extension.

RESULTS

Local control and survival appeared improved in tumors arising in the skull base, following the ability with charged particles to deliver high doses (mean of 65 Gy-equivalent) with relative sparing of the adjacent normal tissues. The Kaplan-Meier 5-year local control was 85% for meningioma, 78% for chondrosarcoma, 63% for chordoma and 58% for other sarcoma. Follow-up ranged from 4-191 months with a median of 51 months.

CONCLUSION

Charged particle radiotherapy is highly effective in controlling cranial base lesions which have have been partially resected. Better tumor localization with CT and MRI, improved 3-D treatment planning and beam delivery techniques have continued to reduce the level of serious complications and increase local control and survival.

Anterior segment complications after helium ion radiation therapy for uveal melanoma. Radiation cataract

OBJECTIVE

To delineate the factors in the development of visually significant cataract after helium ion irradiation of eyes with uveal melanomas.

DESIGN

Retrospective analysis with multivariate analysis using life tables and Cox proportional hazard models in addition to other nonparametric techniques.

PATIENTS

All patients with a noncataractous other eye and adequate dosimetry data who were treated with helium ion irradiation.

RESULTS

Significant cataracts (grade 3+ or 4+ on a 0 to 4+ scale) developed in 129 patients (44%). The risk of cataract development peaked at 3 years (25% per person-year) and then declined to a sustained level of 7% to 9% per year after 7 years. In multivariate analysis, the percentage of lens included in the treatment port was the predominant predictive correlate with time to significant cataract (relative risk of 2.97 for a 25% increase in the percentage of lens in the treatment port). Patient age, preexisting cortical opacity, and ultrasound tumor height were also significant; ciliary body involvement and tumor dose had smaller effects. Kaplan-Meier analysis demonstrated an increased rate of cataractogenesis with each increment of the percentage of lens in the treatment port; when more than half of the lens was in the beam, the risk of cataract exceeded 90% within 7 years.

CONCLUSIONS

Cataract development after helium ion irradiation is a function of the amount of the lens in the beam. Unlike neovascular glaucoma that develops mainly in the first few years after treatment, cataract continues to develop during the entire length of follow-up.

Helium charged particle radiotherapy for meningioma: experience at UCLBL. University of California Lawrence Berkeley Laboratory

PURPOSE

Evaluate the use of helium charged particle radiotherapy in the treatment of residual or unresectable meningioma adjacent to critical structures.

METHODS AND MATERIALS

Twenty-nine patients with meningioma of the skull base or spine were irradiated with helium charged particle radiotherapy at the University of California Lawrence Berkeley Laboratory (UCLBL) during the period 1981-1992. Twenty-six patients were treated for intracranial and three for spinal tumors. Total doses of 53.0-80.4 Gray equivalent (GyE) with a mean of 63 GyE were delivered using the helium ion beam.

RESULTS

Ten-year local control and survival rates calculated by the Kaplan-Meier product limit method were 84% and 80% respectively. Doses of 60.0 GyE were delivered with a low rate of complications. The only failures were in massive, recurrent tumors.

CONCLUSION

High doses using helium charged particle radiotherapy can be safely and effectively delivered to large residual or unresectable meningioma near radiosensitive structures.

Helium ions versus iodine 125 brachytherapy in the management of uveal melanoma. A prospective, randomized, dynamically balanced trial

PURPOSE

Optimal radiation therapy for uveal melanoma is uncertain, and the relative efficacies of radioactive plaques and charged particles are unclear.

METHODS

The authors prospectively studied helium-ion irradiation and iodine 125 (125I) brachytherapy in a randomized, dynamically balanced trial. Of the 184 patients who met the eligibility criteria, 86 were treated with helium ions and 98 with 125I brachytherapy.

RESULTS

No patients with uveal melanoma had a history of systemic malignancy. Tumors were less than 15 mm in maximum diameter and less than 10 mm in thickness. A minimum tumor dose of 70 GyE was delivered to the tumor apex. There was a significantly higher local recurrence rate after 125I brachytherapy than after helium-ion irradiation. Enucleations occurred more frequently after brachytherapy (relative risk = 1.99; 95% confidence interval, 0.78-5.78). More anterior segment complications occurred after helium-ion irradiation. To date, there has been no measurable impact on survival.

CONCLUSIONS

Most uveal melanomas can be managed with radiation with retention of the eye. There was better tumor control with helium-ion irradiation; however, there were more anterior segment complications.

Definitive postoperative irradiation of bile duct carcinoma with charged particles and/or photons

PURPOSE

To determine the rates of survival and local control in patients with bile duct adenocarcinomas treated with post-operative photons and/or charged particles.

METHODS AND MATERIALS

A retrospective study was performed analyzing all patients with bile duct adenocarcinomas who received radiotherapy through the University of California San Francisco and at Lawrence Berkeley Laboratory between 1977 and 1987, a total of 62 patients. University of California San Francisco patients received photon therapy (median dose 5400 cGy), and Lawrence Berkeley Laboratory patients were treated with the charged particles helium and/or neon (median dose 6000 cGyE). Forty-eight patients were treated post-operatively with curative intent, 30 with photons and 18 with particles. Thirty-six patients in the study had gross residual disease; none had microscopically negative margins.

RESULTS

The overall two-year actuarial survival was 28%: 44% for particle-treated patients and 18% for patients treated with photons (p = .048). Median actuarial survival was 23 months in particle patients and 12 months in photon patients. Local control was also improved, though less significantly, in patients treated with particles (median disease-free survival 20 months vs. 4.5 months, p = .054). A univariate and multivariate analysis was performed and revealed that only extent of residual disease predicted local failure and overall survival; no other prognostic factors were identified.

CONCLUSION

Compared to conventional photon radiotherapy, treatment with post-operative charged particle irradiation at Lawrence Berkeley Laboratory appeared to offer a survival advantage in this non-randomized series. Additional investigation into protection of surrounding normal tissue with better dose localization through the use of charged particles is planned.

Evaluation of fixed- versus variable-modulation treatment modes for charged-particle irradiation of the gastrointestinal tract

The clinical usefulness of variable-modulation dose delivery of neon ion and proton beams over fixed-modulation beams is evaluated for several patients with tumors in the gastrointestinal tract by comparing dose distributions, dose volume histograms, and predictions of normal tissue complication probabilities calculated with the two methods. Both techniques provide excellent coverage of the target volume with neon ion and proton beams. The advantage of variable modulation is that less dose is delivered proximal to the target volume. For tumors in the gastrointestinal tract, this implies that less dose is given to the liver, gut, kidneys, and lungs. For the ten patients considered in this study, variable-modulation reduced the total integral dose by an average of 17% for neon ion beams and by 18% for protons as compared to fixed-modulation. If the tumor volume is excluded, the reduction in the integral dose to normal tissues ranged from 15% to 32% for neon ions and from 18% to 34% for proton beams. These gains are larger than those anticipated on the basis of an analytic study by Goitein and Chen [Med. Phys. 10, 831-840 (1983)], which predicted integral dose reductions of the order of 10% for protons and 14% for neon ions. They are also larger than those reported in a similar study by Urie and Goitein [Med. Phys. 16, 593-601 (1989)] for proton irradiation of skull-base tumors. This is probably because the tumors in the GI tract considered in this study were more irregularly shaped than Goitein and Chen's analytic model assumes. The results of this study also suggest that due to increased sparing of normal tissues, the number of different portal directions required to achieve a satisfactory treatment plan will be reduced for variable-modulation beam delivery systems. This implies that variable-modulation treatment plans will be easier to execute than current fixed-modulation plans.

High intensity 125-iodine (125I) plaque treatment of uveal melanoma

PURPOSE

Episcleral 125I plaque therapy of uveal melanoma is an important treatment modality to control tumor, salvage the globe, and potentially preserve vision. We retrospectively analyzed our experience in 239 patients to assess treatment outcome with this technique.

METHODS AND MATERIALS

Between 1983 and 1990, 239 uveal melanoma patients were treated with 125I plaques at the University of California, San Francisco. High intensity 125I seeds in the range of 3-20 mCi were used to give a minimum tumor dose of 70 Gy in 4 days. Initial mean tumor size was 10.9 mm x 9.2 mm x 5.5 mm with a range in tumor diameter from 4 to 18 mm and tumor height from 1.9 to 11.1 mm. Best corrected pre-treatment visual acuity was 20/200 or better in 92% of patients.

RESULTS

Local tumor control was maintained in 91.7% of patients with a mean follow-up of 35.9 months; 19 patients had local tumor progression; mean time to progression was 27.3 mo (1.8 to 60.1 mo). Actuarial local control is 82% at 5 years. Multivariate analysis demonstrates significant correlation of local failure with larger maximum tumor diameter (p = 0.0008), closer proximity to the fovea (p = 0.0001), lower radiation dose (p = 0.0437), and smaller ultrasound height (p = 0.0034). The actuarial incidence of distant metastases is 12% at 5 years with multivariate analysis showing significant correlation only with maximum tumor diameter (p = 0.0064). Visual outcome is 20/200 or better in 58% of patients.

CONCLUSION

While the tumor control rates appear favorable, ocular morbidity is significant. A current randomized trial comparing 125I plaque with Helium ion therapy is in progress with specific comparison of tumor control, survival, and visual outcome.

Charged particle irradiation of sacral chordomas

PURPOSE

The purpose of this report is determine the impact of charged particle irradiation at Lawrence Berkeley Laboratory (LBL) in treating patients with sacral chordomas. Overall survival, local control, complications, and predictive parameters are analyzed.

METHODS AND MATERIALS

Fourteen patients with sacral chordomas were treated with the charged particles helium and neon between 1977 and 1989. The median dose was 7565 cGyE and the median follow up is 5 years. All patients were treated post-operatively; ten had gross residual disease.

RESULTS

Kaplan-Meier survival at 5 years is 85%. Overall 5-year local control is 55%. A trend to improved local control at 5 years was seen in patients treated with neon when compared to patients treated with helium (62% vs 34%), in patients following complete resection versus patients with gross residual tumor (75% vs 40%), and in patients who had treatment courses under 73 days (61% vs 21%). Distant metastases were seen in two patients (14%). No patient developed neurologic sequelae or pain syndromes. One previously irradiated patient required colostomy, one patient had delayed wound healing following a negative post-radiation biopsy, and one patient developed a second malignancy. There were no genitourinary complications.

CONCLUSION

Our experience indicates that post-operative charged particle irradiation of sacral chordomas appears to result in reasonable local control and survival with acceptable risk, and that additional evaluation on the use of heavy charged particles is warranted.

Radiotherapy technique integrates MRI into CT

The 1970s saw the introduction of computed tomography, which enabled soft tissue anatomy to be seen. Today simulation of therapeutic fields by x-ray is augmented by radiotherapy treatment planning using CT data. The 1980s brought magnetic resonance imaging with superior soft tissue contrast. This article describes a technique correlating three-dimensional MRI/CT data sets used routinely in treatment planning of tumors in the head.

Charged particle radiotherapy of paraspinal tumors

Between 1976 and 1987, 52 patients with tumors adjacent to and/or involving the cervical, thoracic, or lumbar spinal cord were treated with charged particles at the University of California Lawrence Berkeley Laboratory. The histologies included chordoma and chondrosarcoma (24 pts), other bone and soft tissue sarcoma (14 pts), and metastatic or unusual histology tumors (14 pts). Radiation doses ranged from 29 to 80 Gray-equivalent (GyE), with a median dose of 70 GyE. Twenty-one patients received a portion of their treatment with photons. Median followup was 28 months. For 36 previously untreated patients, local control was achieved in 21/36 patients and the 3-year actuarial survival was 61%. Of 16 patients treated for recurrent disease, 7/16 were locally controlled and the 3-year actuarial survival was 51%. For patients treated for chordoma and chondrosarcoma, probability of local control was influenced by tumor volume (less than 100 cc or greater than 150 cc) and whether disease was recurrent or previously untreated. Complications occurred in 6/52 patients, including one spinal cord injury, one cauda equina and one brachial plexus injury, and three instances of skin or subcutaneous fibrosis. Charged particle radiotherapy can safely deliver high tumor doses to paraspinal tumors with good local control.

Preliminary results in heavy charged particle irradiation of bone sarcoma

Between 1979 and 1989, 17 patients with unfavorable bone sarcoma were treated wholly or in part with heavy charged particle irradiation (helium and/or neon ions) at the University of California Lawrence Berkeley Laboratory. The majority of tumors were located near critical structures such as the spinal cord or brain. Gross tumor was present in all but two patients at the time of irradiation. Six patients were treated for recurrent disease. Histologies included osteosarcoma, Ewing's sarcoma, and recurrent osteoblastoma. Four of the osteosarcomata were believed to have been induced by previous therapeutic irradiation for various tumors. Follow-up time since initiation of radiation ranged from 7 to 118 months (median 40 months). The 5-year Kaplan-Maier local control rate was 48%; the corresponding survival rate was 41%. Over half the patients succumbed to distant metastases despite the majority of patients receiving chemotherapy. In this preliminary study, we have shown that heavy charged particle irradiation can be effectively used for control of bone sarcoma. A Phase II trial is warranted to determine optimal treatment for unresectable or gross residual disease.

Recurrent locally advanced nasopharyngeal carcinoma treated with heavy charged particle irradiation

Between June 1981 and May 1990, 11 patients with recurrent locally advanced nasopharyngeal carcinoma were treated with heavy charged particle radiation at Lawrence Berkeley Laboratory. All patients had previously undergone full course radiotherapy to a median dose of 70.2 Gy [range 61-81 Gy]. Median time to recurrence was 18.2 months. At the time of heavy charged particle radiotherapy treatment, all had evidence of invasion of the base of skull and 7 of 11 had cranial nerve deficits. None of the patients were candidates for brachytherapy because of tumor extent or poor geometry. The tumor histology was squamous cell carcinoma in 10 patients and lymphoepithelioma in one patient. Ten of the 11 patients had received chemotherapy prior to re-irradiation. The heavy charged particle tumor dose delivered ranged from 31.80 GyE to 62.30 GyE (average 50.25 GyE, median 50 GyE). Local control was achieved in 45%. Median survival was 42 months. Actuarial survival was 59% at 3 years and 31% at 5 years (Kaplan-Meier). There were no fatal complications. The results in treating locally advanced recurrent nasopharyngeal carcinoma with heavy charged particles appear superior to those reported by others using photon therapy.

The effect of patient motion on dose uncertainty in charged particle irradiation for lesions encircling the brain stem or spinal cord

A specialized charged-particle radiotherapy technique developed at Lawrence Berkeley Laboratory (LBL) is applied to patients with lesions abutting or surrounding the spinal cord or brain stem. This technique divides the target into two parts, one partially surrounding the critical structure (brain stem or spinal cord) and a second excluding the critical structure and abutting the first portion of the target. Compensators are used to conform the dose distribution to the distal surface of the target. This technique represents a novel approach in treating unresectable or residual tumors surrounding the spinal cord or brain stem. Since the placement of the patient with respect to beam-shaping devices is critical for divided-target treatments, a method for calculating dose distributions reflecting random patient motion is proposed, and the effects of random patient motion are studied for two divided-target patient examples. Dose-volume histograms and a normal-tissue complication probability model are used in this analysis. For the patients considered in this study, the normal-tissue-complication probability model predicts that random patient motion less than or equal to 0.2 cm is tolerable in terms of spinal cord complications.

Integration of multimodality imaging data for radiotherapy treatment planning

This paper describes computational techniques to permit the quantitative integration of magnetic resonance (MR), positron emission tomography (PET), and x-ray computed tomography (CT) imaging data sets. These methods are used to incorporate unique diagnostic information provided by PET and MR imaging into CT-based treatment planning for radiotherapy of intracranial tumors and vascular malformations. Integration of information from the different imaging modalities is treated as a two-step process. The first step is to determine the set of geometric parameters relating the coordinates of two imaging data sets. No universal method for determining these parameters is appropriate because of the diversity of contemporary imaging methods and data formats. Most situations can be handled by one of the four different techniques described. These four methods make use of specific geometric objects contained in the two data sets to determine the parameters. These objects are: (a) anatomical and/or fiducial points, (b) attached line markers, (c) anatomical surfaces, and (d) outlines of anatomical structures. The second step involves using the derived transformation to transfer outlines of treatment volumes and/or anatomical structures drawn on the images of one imaging study to the images of another study, usually the treatment planning CT. Solid modelling and image processing techniques have been adapted and developed further to accomplish this task. Clinical examples and phantom studies are presented which verify the different aspects of these techniques and demonstrate the accuracy with which they can be applied. Clinical use of these techniques for treatment planning has resulted in improvements in localization of treatment volumes and critical structures in the brain. These improvements have allowed greater sparing of normal tissues and more precise delivery of energy to the desired irradiation volume. It is believed that these improvements will have a positive impact on the outcome of radiation therapy.

Sensitivity of helium beam-modulator design to uncertainties in biological data

The goal in designing beam-modulating devices for heavy charged-particle therapy is to achieve uniform biological effects across the spread-peak region of the beam. To accomplish this, the linear-quadratic model for cell survival has been used to describe the biological response of the target cells to charged-particle radiation. In this paper, the sensitivity of the beam-modulator design in the high-dose region to the values of the linear-quadratic variables alpha and beta has been investigated for a 215-MeV/u helium beam, and implications for higher LET beams are discussed. The major conclusions of this work are that, for helium over the LET range of 2 to 16 keV/mu, uncertainties in measuring alpha and beta for a given cell type which are of the order of 20% or less have a negligible effect on the beam-modulator design (i.e., on the slope of the spread Bragg peak); uncertainties less than or equal to 10% in the dose-averaged LET at each depth are unimportant; and, if the linear-quadratic variables for the tumor differ from those used in the beam-modulator design by a constant factor between about 0.5 and 3, then the resultant nonuniformity in the photon-equivalent dose delivered to the tumor is within +/- 25%. It is also shown that for any ion, if the nominal values of alpha or beta used by the beam-modulator design program differ from their actual values by a constant factor, then the maximum errors possible in the beam-modulator design may be characterized by two limiting depth-dose curves such that the ratio of the dose at the proximal end of the spread Bragg curve to the dose at the distal end of the spread peak is given by alpha distal/alpha prox for the steepest curve, and square root of beta distal/beta prox for the flattest curve.

Design of beam-modulating devices for charged-particle therapy

The computer modeling program used to design beam-modulating devices for charged-particle therapy at Lawrence Berkeley Laboratory has been improved to allow a more realistic description of the beam. The original program used a single calculated Bragg peak to design the spread Bragg peak. The range of this curve was shifted so that Bragg curves of varying ranges could be superimposed. The new version of the program allows several measured Bragg curves with different ranges to be used as input, and interpolates between them to obtain the required data for the superposition calculation. The experimental configuration for measuring these input curves simulated therapy conditions. Seven beam-modulating propellers with spread Bragg-peak widths ranging from 2.2 to 14.4 cm were designed and constructed for a 215-MeV/u helium beam using this new design program. Depth-dose distributions produced by these new propellers were in good agreement with predicted distributions, and these propellers are currently being used clinically.

Neon ion radiotherapy: results of the phase I/II clinical trial

Neon ion radiotherapy possesses biologic and physical advantages over megavoltage X rays. Biologically, the neon beam reduces the oxygen enhancement ratio and increases relative biological effectiveness. Cells irradiated by neon ions show less variation in cell-cycle related radiosensitivity and decreased repair of radiation injury. The physical behavior of heavy charged particles allows precise delivery of high radiation doses to tumors while minimizing irradiation of normal tissues. In 1979 a Phase I-II clinical trial was started at Lawrence Berkeley Laboratory using neon ions to irradiate patients for whom conventional treatment modalities were ineffective. By the end of 1988 a total of 239 patients had received a minimum neon physical dose of 1000 cGy (median follow-up for survivors 32 months). Compared with historical results, the 5-year actuarial disease-specific survival (DSS5) and local control (LC5) rates suggest that neon treatment improves outcome for several types of tumors: a) advanced or recurrent macroscopic salivary gland carcinomas (DSS5 59%; LC5 61%); b) paranasal sinus tumors (DSS5 69%; LC5 69% for macroscopic disease); c) advanced soft tissue sarcomas (DSS5 56%, LC5 56% for macroscopic disease); d) macroscopic sarcomas of bone (DSS5 45%; LC5 59%); e) locally advanced prostate carcinomas (DSS5 90%; LC5 75%); and f) biliary tract carcinomas (DSS5 28%; LC5 44%). Treatment of malignant gliomas, pancreatic, gastric, esophageal, lung, and advanced or recurrent head and neck cancer has been less successful; results for these tumors appear no better than those achieved with conventional x-ray therapy. These findings suggest that Phase III trials using the neon beam should be implemented for selected malignancies.

Uveal melanoma: development of metastases after helium ion irradiation

Forty-two (16%) of 261 patients with ocular melanoma who were treated with helium ions between January 1978 and November 1986 have developed metastatic disease. The time between start of helium ion treatment and recognition of metastatic disease ranged from 3 to 67 months (median, 27 months). The mean pretreatment tumor height in the patients with metastases was 7.7 mm. All 42 patients who developed metastatic disease have died. The median survival after diagnosis of metastatic disease was 5 months; the longest survival was 49 months. The most common site of metastasis was the liver (n = 34). Four (10%) of the 42 patients with metastases also had local recurrence of the tumor. Multivariate analysis identified three variables that predicted independently the development of metastases and lack of survival. These variables are anterior location of tumor (P = .027), tumor height greater than 5 mm (P = .02), and tumor diameter greater than 10 mm (P = .0075).

Evaluation of acute radiation optic neuropathy by B-scan ultrasonography

We studied the accuracy of B-scan ultrasonography to diagnose radiation-induced optic neuropathy in 15 patients with uveal melanoma. Optic neuropathy was diagnosed by an observer masked as to clinical and photographic data. We analyzed planimetry area measurements of the retrobulbar nerve before and after irradiation. The retrobulbar area of the optic nerve shadow on B-scan was quantitated with a sonic digitizer. Increased optic nerve shadow area was confirmed in 13 of 15 patients who had radiation optic neuropathy (P less than .004). The correct diagnosis was confirmed when the results of ultrasound were compared to fundus photography and fluorescein angiography. In 13 patients there was acute radiation optic neuropathy. Two patients did not show an enlarged retrobulbar optic nerve, and the clinical appearance suggested early progression to optic atrophy. Ultrasonography documents the enlargement of the optic nerve caused by acute radiation changes.

Ciliary body melanoma treated with helium particle irradiation

Melanoma involving the ciliary body is a rare tumor which carries a poor prognosis when compared to all uveal melanoma. We have treated 54 patients with ciliary body melanoma using helium ions from 1978 to 1985. Because of the high rate of metastatic disease, the 5-year disease specific survival rate is only 59% despite a 5-year local control rate of 98%. The greatest diameter of the tumor was predictive of loss of vision and enucleation (p = .05, p = .04, respectively). Multivariate analysis showed that the greatest diameter of the tumor was the most important predictor of death from metastases. The incidence of neovascular glaucoma at 5 years is 43%. The 5-year actuarial rate of enucleation is 26%. Enucleation was done for pain and/or neovascular glaucoma. Univariate analysis showed treatment volume to be a statistically significant predictor for the development of neovascular glaucoma (p = .0017) and enucleation (p = .0078). Seventy percent of neovascular glaucoma occurred in patients with treatment volume greater than 5.5 cc. Seventy-four percent occurred in patients with an initial ultrasound height greater than 9.2 mm. Using this information, patients at high risk for neovascular glaucoma could be considered for prophylactic treatment with panretinal photocoagulation.

Five-year follow-up of helium ion therapy for uveal melanoma

One hundred sixty-four patients with uveal melanoma were treated with helium ion irradiation prior to May 1984, and the data were analyzed in June 1989. Most uveal melanomas were large, with a mean tumor thickness of 6.5 mm; approximately 60% of the patients had tumors that extended anterior to the equator. A complete follow-up was obtained for all patients. One hundred twelve patients were alive at the time of this report; 18% of the patients developed clinical and laboratory evidence of metastases and eventually died of widespread tumor. Eighty-four percent of eyes were retained. Data were analyzed with a number of parametric and nonparametric techniques. Larger tumors and those located in close proximity to the optic nerve and fovea had a higher incidence of most complications, especially visual loss.

Uveal melanoma radiation. 125I brachytherapy versus helium ion irradiation

The optimum radiation therapy for uveal melanoma is uncertain. Both helium ion irradiation and 125I brachytherapy have been used to treat this neoplasm. This investigation analyzed the control and complication rates of uveal melanomas treated with helium ions of 125I plaques. In both a retrospective and a prospective dynamically balanced study, the control rates appeared to be similar. There were more posterior segment complications after 125I plaques and more anterior segment complications, including neovascular glaucoma, after helium ion irradiation. The follow-up period is too short to draw definitive conclusions on the radiation complications. Overall, approximately 89% of eyes were retained and less than 4% of treated eyes were removed because of failure to control the tumor.

The effect of silicone nasolacrimal intubation on epiphora after helium ion irradiation of uveal melanomas

We evaluated prophylactic silicone tube intubation of the nasolacrimal drainage system prior to helium ion irradiation of uveal melanomas located on the nasal side of the globe. Twelve patients received silicone tubes and were compared to a control group of 12 patients with irradiated nasal tumors without silicone tubes. Symptoms of nasolacrimal duct obstruction and epiphora were evaluated by means of a questionnaire. All patients had nasolacrimal duct irrigation. Patients intubated before irradiation maintained patency (11 of 12), whereas those in the control group did not (zero of 12) (P less than .0014); ten of 12 control patients had closure of both superior and inferior puncta. No significant difference in symptoms of epiphora was observed between the two groups.

Charged particle radiotherapy for lesions encircling the brain stem or spinal cord

Since 1981, a specialized technique has been under development at the University of California Lawrence Berkeley Laboratory for charged particle irradiation of tumors partially or completely encircling the brain stem or spinal cord. By dividing the target volume into two or more portions and using a combination of beams, a reasonably homogeneous irradiation of the target volume can be obtained which protects critical CNS structures from over-irradiation. This technique requires knowledge of the physical and biological effects of charged particles, precise, reproducible patient immobilization, careful treatment planning based upon Metrizamide contrast CT and/or MRI scanning, compensation for tissue inhomogeneities, and accurate, verifiable radiation delivery. Uncertainties in the dose distribution must be taken into account when prescribing treatment. We have used this technique in 47 patients with a variety of tumors abutting the brain stem and spinal cord, including chordoma, chondrosarcoma, meningioma, osteosarcoma and metastatic tumors. The results have shown a significant local control rate (62%) and the incidence of serious complications has been acceptable (13%). The median follow-up is 20 months with a range of 6-90 months. We conclude that charged particles can be safely and effectively used to irradiate lesions encircling the brain stem or spinal cord to doses higher than can be achieved with low-LET irradiation.

Effect of various doses of radiation for uveal melanoma on regression, visual acuity, complications, and survival

We reviewed 284 choroidal and ciliary body melanomas treated with 50, 60, 70, or 80 gray equivalents (GyE) of helium ion radiation. Multivariate methods of data analysis were used to adjust for differences between dose groups with respect to the characteristics of patients (and their tumors). Radiation dose level did not affect survival, complications, visual outcome, or tumor regression in this model. The minimum radiation dose necessary to achieve tumor control with charged particles may be less than 50 GyE.

Radiosensitization produced by iododeoxyuridine with high linear energy transfer heavy ion beams

Little is known about radiosensitization produced by iododeoxyuridine (IUDR) with high linear energy transfer radiation. Likewise, the effect of IUDR on repair of sublethal or potentially lethal damage is unclear. A series of in vitro experiments was performed examining these aspects of IUDR radiosensitization. Human T1 cells were grown in the presence of 3.0 micromolar IUDR for 72 hours (approximately three doubling times), an exposure which resulted in minimal cytotoxicity to unirradiated cells. As the cells entered plateau phase they were exposed to X rays and a variety of heavy ion beams. Sensitization was found to decrease as linear energy transfer (LET) increased. No sensitization took place in an extremely high LET Lanthanum ion beam (1000 keV/micrometer). However, IUDR produced significant sensitization in the Neon ion beam currently used to treat cancer patients at Lawrence Berkeley Laboratory. Sensitization enhancement ratios at the 40% cell survival level were found to be 1.8 for X rays, 1.5 for the proximal Bragg peak of the clinical Neon beam, and 1.3 for the distal peak of the clinical Neon beam. Cell survival curves fitted to the linear-quadratic model showed IUDR significantly increased the value of the linear component (alpha) in beams with LETs below 40 keV/micron. The value of the quadratic component (beta) was unaffected by IUDR, regardless of LET. Split-dose experiments with both X rays and proximal peak Neon ions revealed IUDR did not affect sublethal damage repair. Similarly, delayed-plating experiments showed IUDR did not affect repair of potentially lethal damage. In contrast to cells unexposed to IUDR, IUDR-treated cells showed near-equal levels of cell killing throughout the extended Bragg peak of the clinical Neon beam. These findings suggest that the addition of IUDR to Neon ion radiotherapy could enhance the therapeutic ratio of the clinical Neon beam.

Charged particle irradiation of chordoma and chondrosarcoma of the base of skull and cervical spine: the Lawrence Berkeley Laboratory experience

Forty-five consecutive patients with chordoma or chondrosarcoma at the base of skull or cervical spine were treated at the University of California Lawrence Berkeley Laboratory (UCLBL) and University of California School of Medicine, San Francisco (UCSF) between November 1977 and October 1986. All patients had undergone a subtotal surgical resection. Twenty-three patients were treated definitively with charged particles, 13 patients were treated with photons and particles, and 9 patients were treated for recurrent disease. Total doses ranged from 36 to 80 Gray equivalent (GyE). Thirty-three patients are alive with a minimum followup of 1 year. The actuarial survival and local control for all patients at 5 years is 62% and 59%, respectively. Patients treated for primary disease had a 78% actuarial local control rate at 2 years, whereas the rate for patients with recurrent disease was 33%. Patients with smaller visible tumor volumes (less than 20 cc) had a significantly better local control rate than patients with larger tumor volumes (80% vs 33% actuarial rate at 5 years). Patients with chondrosarcoma had the highest local control rate, as did patients treated with particles alone. Complications included 3 patients with unilateral visual loss, two patients who became blind, and 4 patients with radiation injury to the brainstem.

Vision following helium ion radiotherapy of uveal melanoma: a Northern California Oncology Group study

One hundred eighty-six uveal melanoma patients were treated with helium ion radiotherapy at Lawrence Berkeley Laboratory and followed for at least 6 months. (Follow-up times ranged from 6 to 90 months; median 26.4 months.) At last examination, 92 of 186 patients (49%) had visual acuity of 20/200 or better in the treated eye. Univariate statistical analysis revealed that post-treatment vision correlated with tumor size, distance between tumor and optic disc, distance between tumor and fovea, pretreatment visual acuity, dose delivered to the optic disc, and dose delivered to the fovea (p less than .05). Neither the maximum tumor dose nor site of tumor origin (ciliary body vs. choroid) correlated with post-treatment vision on a univariate basis. However, multivariate statistical analysis revealed that the strongest independent risk factors influencing vision outcome (p less than .05) were tumor size, pretreatment visual acuity, tumor-fovea distance, and maximum tumor dose. Neither the fovea dose nor the dose to optic disc appeared to significantly affect vision outcome when other variables were taken into account. These results suggest that post-treatment visual acuity of 20/200 or better can be achieved in one-half of uveal melanoma patients treated using helium ion irradiation. Several independent risk factors affecting vision outcome have been identified.

Comparison of helium-ion radiation therapy and split-course megavoltage irradiation for unresectable adenocarcinoma of the pancreas. Final report of a Northern California Oncology Group randomized prospective clinical trial

Forty-nine patients with locally advanced carcinoma of the pancreas were treated in a randomized, prospective study comparing definitive helium ion radiation therapy with conventional split-course megavoltage photon irradiation. Patients in each treatment arm underwent exploratory staging laparotomy followed by concurrent radiation therapy and 5-fluorouracil chemotherapy. Patients treated with photons received 6,000 cGy over a period of 10 weeks; patients treated with helium irradiation received a 6,000-7,000-cGy-equivalent dose over a period of 8-9 weeks. There was no significant difference in overall survival between patients in the two treatment arms (P = .29). Patients treated with helium ions had a slightly longer median survival (7.8 months) than the photon-treated patients (6.5 months). Local control rates were slightly higher in the helium-treated patients (10% vs 5%). Complications included one chemotherapy-related death. Four of the five helium-treated patients who survived longer than 18 months died of local failure without distant metastases. These results suggest that more aggressive local therapy could result in improved survival in helium-treated patients.

Treatment planning study for carcinoma of the esophagus: helium ions versus photons

Helium ion radiotherapy significantly reduces dose to adjoining critical structures in the treatment of carcinoma of the esophagus when the same treatment plan is compared with megavoltage photon therapy. A five-field 18 MV photon treatment plan, selected to minimize lung dose, is compared with helium ions using the same field configuration. Dose volume histograms show target coverage, as well as dose delivered to critical structures lung, heart, mediastinum, and spinal cord. Although both helium ions and photons deliver approximately the same lung dose for this treatment plan, radiation to the heart and spinal cord from this field arrangement is significantly reduced with the helium ion beam. The concentration of dose at the tumor site, while sparing surrounding normal tissue, is characteristic of charged particle therapy, particularly with light ions, which includes particles with Z from that of protons (Z = 1) through that of neon (Z = 10).

Charged particle radiotherapy of selected tumors in the head and neck

For selected tumors in some sites in the head and neck region, charged particles such as protons or helium, carbon, neon and silicon ions provide improved dose distributions, higher tumor doses, and an increased chance of local control and prolonged survival. In tumors with "radioresistant" histologies, slow growth kinetics and/or hypoxic cells, the high-LET component of neon or silicon ions may also offer and added potential for increased effect on tumors. Sixty-seven (67) evaluable patients with tumors in the head and neck region having a histology other than squamous carcinoma received partial or full treatment with charged particles at the University of California Lawrence Berkeley Laboratory. The tumor sites included base of skull or cervical spine, salivary glands, paranasal sinuses, nasopharynx, and miscellaneous sites such as lacrimal gland, soft tissues of the neck, or thyroid. Follow-up ranges from 1-9 years with a mean of 36 months and a median survival (Kaplan-Meier technique) of 50 months. The actuarial local control rate is 60% at 24 months post-treatment. Thirty-one (31) patients with squamous carcinoma of various sites in the head and neck have also been treated using charged particle irradiation; local control was lower (11 of 31 pts) and survival shorter (mean: 9 months) in this group of patients with advanced squamous carcinoma.

[Heavy particle radiotherapy at the University of California Lawrence Berkeley Laboratory. Clinical studies by the Northern California Oncology Group]

At the university of California Lawrence Berkeley Laboratory, patients have been irradiated for 10 years with heavy ions (He, C, Ne, Si). Due to the biologic efficacy of this type of radiation as well as the possibility of a precise dose application, the tumors can be irradiated with very high doses without exposing the surrounding tissues. The experience gained in the treatment of more than 800 patients is presented. It shows that this radiation can be used to localize tumors situated near to particularly radiosensitive organs such as skull base, paraspinal region, and the eye.

Heavy charged particle therapy of bone and soft tissue sarcoma. A phase I-II trial of the University of California Lawrence Berkeley Laboratory and the Northern California Oncology Group

At the University of California Lawrence Berkeley Laboratory and the Northern California Oncology Group, a preliminary study of heavy charged particle radiotherapy in soft tissue and bone sarcoma has been carried out. Fifty-two patients with bone or soft tissue tumors were treated wholly or in part with heavy charged particles from 1978 to 1985. Eleven patients, considered inevaluable for purposes of this analysis, received less than 50 Gray-equivalents (GyE) because of the following: progressive disease (three patients); palliative treatment due to recurrent disease after previous radiation therapy (three patients); or since they were part of preliminary studies of relative biological effectiveness (RBE) (five patients). Forty-one patients received from 50 to 78.5 GyE, with a mean of 65 GyE. They had an average of 23 months follow-up, ranging from 4 to 78 months. In patients with paraspinal chondrosarcoma 9 of 11 had local control, with a mean follow-up time of 32 months. In the remaining patients with other histologies, 19 of 30 were controlled within the irradiated area, with a mean follow-up time of 20 months. Serious complications were encountered in the CNS (four patients), in the bowel (one patient), and in bone (one patient). Heavy charged particle radiotherapy appears to be of value in treating bone or soft tissue sarcoma; further trials are planned.

[Acute kidney failure secondary to ophidian bothropic and crotalid accidents. Analysis of 63 cases]

Sessenta e três pacientes com insuficiência renal aguda secundária a acidente ofídico foram tratados no CTI do Hospital das Clínicas da UFMG. Em 32 pacientes (51%) o acidente foi produzido por serpentes do gênero Bothrops (grupo bio-trópico) e em 32 pacientes (49%) pela cascavel sul-americana (grupo crotálico). As principais complicações apresentadas pelos pacientes foram a uremia (100% dos casos), hiperpotassemia (89% dos casos), anemia (78% dos casos), infecção urinária (37% dos casos), hiper-hidratação (17% dos casos), parada cardíaca (14% dos casos) e edema agudo dos pulmões (11% dos casos). Cinco pacientes do grupo crotálico (16%) tiveram insuficiência respiratória aguda atribuída à ação neurotóxica do veneno, quatro dos quais se recuperaram completamente. Sete pacientes do grupo botrópico (22%) tiveram necrose cortical renal diagnosticada em cinco através da biópsia renal e em dois na necropsia. Quarenta e cinco pacientes (71%) foram tratados com diálise peritoneal e a hemodiálise foi necessária em dois pacientes, um dos quais havia sido submetido a diálise peritoneal. Em 17 pacientes (27%) o tratamento foi conservador. Cinqüenta e cinco pacientes receberam alta hospitalar, quatro dos quais com insuficiência renal crônica secundária a necrose cortical renal e oito (13%) faleceram. Os óbitos foram atribuídos a edema pulmonar agudo em quatro pacientes, a estado de choque em dois pacientes e a coma e infecção respiratória após parada cardíaca em dois pacientes.

Uveal melanoma necrosis after helium ion therapy

A 71-year-old man underwent enucleation because of intractable pain ten months after receiving helium ion therapy for a uveal melanoma. There was no clinical or ultrasonographic evidence of tumor regression but histologically the tumor appeared almost entirely necrotic.

Early results of ion beam radiation therapy for sacral chordoma. A Northern California Oncology Group Study

The authors report on eight patients with sacral chordoma treated with ion beam radiation therapy. Ion beams have favorable physical and biological characteristics when compared to conventional radiation therapy beams of x-rays, gamma rays, or electrons. This treatment technique has been developed to exploit those advantages. With this technique it is possible to deliver a much higher tumor dose than that usually given with conventional beams, and to date no significant normal-tissue morbidity has been noted. Seven of the eight patients currently have local control of their tumor; however, follow-up time is too short to judge the long-term local control rate of this treatment technique.

Dose volume histogram analysis of liver radiation tolerance

Eleven patients with carcinoma of the pancreas or biliary system received heavy charged particle radiation treatments and whole liver heavy charged particle radiation at Lawrence Berkeley Laboratory. Doses to the whole liver ranged from 10 to 24 Gray-equivalent (the biological equivalent of 10 to 24 Gray of low-LET photon radiation), whereas the dose to the primary lesion ranged from 53.5 to 70 Gray-equivalent (GyE). The fraction size was 2 to 3 GyE. The liver received partial as well as whole organ irradiation. Integral dose volume histograms for the liver were obtained in all 11 patients. An integral dose volume histogram displays on the ordinate the percentage of liver that was irradiated in excess of the dose specified on the abcissa. In this study, the clinical liver radiation tolerance of these patients is correlated with the information contained in an integral dose volume histogram. One patient developed radiation hepatitis. The integral dose volume histogram of this patient differed from the dose volume histograms of the other 10 patients. This difference was greatest in the range of doses between 30 and 40 GyE. Our results suggest that liver doses in excess of 30 to 35 GyE should be limited to 30% of the liver or less when 18 GyE of whole liver radiation is delivered at 2 GyE per fraction in addition to primary radiation of the pancreas or biliary system.