Pelvic mass: CT-guided interstitial catheter implantation with high-dose-rate remote afterloader.

A technique is presented for computed tomography (CT)-guided interstitial catheter placement and treatment planning for high-dose-rate brachytherapy. In a 66-year-old woman with adenocarcinoma of unknown origin that had metastasized to the right ilium, interstitial brachytherapy catheters were placed by means of CT guidance. With use of a treatment planning system with dose optimization, an excellent dose distribution was obtained with minimal dose being delivered to the surrounding critical tissues. For selected patients, this procedure can provide effective and safe local treatment for solid tumors.

Statistical approach to X-ray CT imaging and its applications in image analysis. I. Statistical analysis of X-ray CT imaging.

A statistical description of X-ray CT (computerized tomography) imaging, from the projection data to the reconstructed image, is presented. The Gaussianity of the pixel image generated by the convolution (image reconstruction) algorithm is justified. The conditions for two pixel images to be statistically independent (for a given probability) and the conditions for a group of pixel images to be a spatial stationary random process and ergodic in mean and autocorrelations are derived. These properties provide the basis for establishing the stochastic image model and conducting the statistical image analysis of X-ray CT images.

Statistical approach to X-ray CT imaging and its applications in image analysis. II. A new stochastic model-based image segmentation technique for X-ray CT image.

For pt.I, see ibid., vol.11, no.1, p.53.61 (1992). Based on the statistical properties of X-ray CT imaging given in pt.I, an unsupervised stochastic model-based image segmentation technique for X-ray CT images is presented. This technique utilizes the finite normal mixture distribution and the underlying Gaussian random field (GRF) as the stochastic image model. The number of image classes in the observed image is detected by information theoretical criteria (AIC or MDL). The parameters of the model are estimated by expectation-maximization (EM) and classification-maximization (CM) algorithms. Image segmentation is performed by a Bayesian classifier. Results from the use of simulated and real X-ray computerized tomography (CT) image data are presented to demonstrate the promise and effectiveness of the proposed technique.

Alumina ceramic as a biomaterial for use in afterloading radiation catheters for hyperthermia.

A major technical challenge to the use of interstitial hyperthermia in malignant brain tumors is the production of a well-defined, uniform hyperthermal field. In theory, A 915-MHz microwave antenna should allow fewer antennas to be used and cause less mechanical brain damage; however, standard radiation afterloading catheters require antennas to be 12 cm long; this is clearly impractical for intracranial use. Since alumina ceramic (Al2O3) catheters permit short microwave antennas (3-5 cm in length) to function properly in neural tissue, it is important to test the biocompatibility of alumina for use in combined interstitial microwave hyperthermia and brachytherapy. A 5-mm length of alumina catheter was implanted into the brains of 15 white rats. The animals were killed at 3, 7, 14, 28, and 56 days. Histological examination revealed only minor mechanical damage and no encapsulation until 1 month; even then, the glial wall was only a few cell layers thick. Five animals received implants and were killed at similar intervals for x-ray microanalysis with the scanning electron microscope. No migration of aluminum into the brain was detected when compared with two control animals that did not receive implants and an alumina blank. Although we measured 50% attenuation of the radiation from iridium-192 sources in alumina catheters as compared with conventional ones, alumina catheters can still be used for interstitial radiation by increasing either the activity of the seeds or the duration of treatment.

Technical aids for the flexible use of the Leksell stereotactic system.

As part of a multimodality therapy program for intracranial tumours, 105 stereotactic and implant procedures have been carried out utilizing the CT-compatible Leksell stereotactic system. In the iridium implant series, 86 catheters have been implanted for an average of 3.6 targets per patient. There have been no deaths or missed targets and only two incidential haemorrhages detected. In order to facilitate the reliability, safety and speed of multiple catheter insertion, several techniques have been developed including: (a) a standardized single-length catheter and flange system; (b) a ceramic catheter for microwave hyperthermia; (c) a mnemonic card for ease of calculation; (d) a radiation shield for nursing; (e) a stereotactic drill and surgical approaches to far lateral and posterior fossa targets. Principles for the use of these technical aids are discussed.

Once-a-week vs conventional daily radiation treatment for lung cancer: final report.

This is the final report of a prospective randomized clinical trial which began in 1982 and explored once-a-week hypofractionation in lung cancer patients with unresectable, non-metastatic, measurable, loco-regionally advanced disease. Stratification to this protocol has been done by histology, stage, and performance status categories. Patients with ipsilateral supraclavicular and/or brain metastases as the only evidence of distant spread, have been included in the study, but were stratified and analyzed separately. The two protocol arms were: (I) Conventional daily radiation [5 x W]-5 daily fractions of 2 Gy each to a total dose of 60 Gy in 6 weeks, protecting the spinal (SC) at 45 Gy and (II) Once-a-week radiation [1 x W]-one weekly fraction of 5 Gy each to a total tumor dose of 60 Gy in 12 weeks protecting the SC at 30 Gy. A total of 150 patients have been entered. Of these, 30 pts. are inevaluable, but the reasons of non-compliance, progression of disease or death due to intercurrent disease were of equal incidence in both groups. Of the 120 evaluable patients, 63 were treated 5 x W and 57 with 1 x W therapy. Complete tumor responses are similar in both arms with 1 x W pts demonstrating a numerical advantage (26% vs 17%). The average follow-up of the entire series is 3 yrs with a range of 12-66 months. Survival data is comparable in both groups with the 12 and 24 month actuarial survival of 49% and 23% for the 5 x W arm and 59% and 29% for the 1 x W arm. 1 x W patients continue to show a better tolerance than 5 x W pts. There are sufficient long-term survivors in both arms to assess chronic toxicity. The number of patients alive at 12, 18, and 24 months were 25, 11, and 5 for the 5 x W arm and 29, 16, and 7 for the 1 x W arm. No significant differences in late reactions have been noted. The longest surviving patient in the 1 x W arm is now 48 months after treatment.

A phase I/II trial of whole-abdominal plus pelvic irradiation for Astler-Coller stage beta 2, C colorectal cancer.

From 1982 to 1986, after radical surgery (S) for carcinoma of the rectum and rectosigmoid colon, 25 consecutive patients were entered into a Phase I/II study exploring adjuvant radiation (RT). The latter was given with a single fraction of whole abdomen (mid-body) irradiation (MBI), followed by conventional whole pelvis irradiation (WPI). The minimum follow-up time was 12 months, and the maximum was 44 months. There was escalation of the single MBI dose: 5 Gy in 11 patients, 6 Gy in two patients, and 8 Gy in 10 patients. The 2-year survival rate has been 100 and 45% for Stages B2 and C patients. Only 1/7 Astler-Coller Stage B2 patients failed; this failure was in the lungs. Seven of 15 patients with Stage C failed: one locally, three in the liver, and three in the lungs. Single MBI doses greater than 5 Gy have yielded a high incidence of intestinal obstruction when combined with routine WPI. Consequently, this combination requires both some modification and careful attention if used in future trials exploring new treatment approaches for colorectal cancer.

Neuro-oncology update: radiation safety and nursing care during interstitial brachytherapy.

Radiation control and safety are major considerations for nursing personnel during the care of patients receiving brachytherapy. Since the theory and practice of radiation applications are not part of the routine curriculum of nursing programs, the education of nurses and other health care professionals in radiation safety procedures is important. Regulatory agencies recommend that an annual safety course be given to all persons frequenting, using, or associated with patients containing radioactive materials. This article presents pertinent aspects of the principles and procedures of radiation safety, the role of personnel dose-monitoring devices, and the value of additional radiation control features, such as a lead cubicle, during interstitial brain implants. One institution's protocol and procedures for the care of high-intensity iridium-192 brain implants are discussed. Preoperative teaching guidelines and nursing interventions included in the protocol focus on radiation control principles.

Radiation control in the intensive care unit for high intensity iridium-192 brain implants.

A bedside lead cubicle was designed to minimize the radiation exposure of intensive care unit staff during routine interstitial brain irradiation by removable, high intensity iridium-192. The cubicle shields the patient without restricting intensive care routines. The design specifications were confirmed by exposure measurements around the shield with an implanted anthropomorphic phantom simulating the patient situation. The cubicle reduces the exposure rate around an implant patient by as much as 90%, with the exposure level not exceeding 0.1 mR/hour/mg of radium-equivalent 192Ir. Evaluation of data accumulated for the past 3 years has shown that the exposure levels of individual attending nurses are 0.12 to 0.36 mR/mg of radium-equivalent 192Ir per 12-hour shift. The corresponding range for entire nursing teams varies between 0.18 and 0.26. A radiation control index (exposure per mg of radium-equivalent 192Ir per nurse-hour) is thus defined for individual nurses and nursing teams; this index is a significant guide to the planning of nurse rotations for brain implant patients with various 192Ir loads. The bedside shield reduces exposure from 192Ir implants by a factor of about 20, as expected, and the exposure from the lower energy radioisotope iodine-125 is barely detectable.

A prospective randomized trial comparing once-a-week vs daily radiation therapy for locally-advanced, non-metastatic, lung cancer: a preliminary report.

This is the first report of an on-going Phase III protocol for patients with locally-advanced, non-metastatic, measurable lung cancer. The study randomizes two arms: 6000 rad using 500 rad fractions once a week (1 X W) for 12 weeks with spinal cord (SC) protection at 3000 rad; and 6000 rad using 200 rad fractions daily (5 X W) for 6 weeks with SC protection at 4500 rad. Both arms use an initially large loco-regional field that is further reduced when tumor doses reach 3000 rad in (1 X W) arm and 5000 rad in (5 X W) arm. The protocol was activated April 1982; as of August 1984, it had accrued 100 patients of whom 68 were evaluable [29 (1 X W) and 39 (5 X W)]. There have been no major differences in tumor responses or failure patterns between the (1 X W) and (5 X W) arms; response rates have been 69 and 64%; CR 31 and 20%; total incidence of local failures 20 and 23%; and overall incidence of distant failures 34 and 43%, respectively. The (1 X W) arm has been far better tolerated with 76% of its patients free of any esophagitis and 97% without weight loss, as compared to only 33 and 67% in the (5 X W), respectively. The (1 X W) arm has not conveyed loss in tumor control effectiveness, in-treatment progression, or higher incidence of distant spread. Subacute and chronic complications have been minimal with either treatment. No fatal or life-threatening toxicities have occurred; the incidence of severe complications has been 7% in the (1 X W) arm and 8% in the (5 X W) arm. Nevertheless, the number of patients alive and at risk greater than or equal to 12 months is still relatively small; definitive statements regarding very late toxic reactions cannot yet be made. Compared to their protocyptes [a (1 X W) Pilot Study and the 6000 rad/6 weeks arm of RTOG Protocol 73-01], results in the present protocol arms have not been different from what was expected. Once a week RT yields results that appear no different from those achieved with conventional RT in lung cancer.

Technique and preliminary results of interstitial irradiation for primary brain tumors.

We have conducted a phase-I clinical trial of CT-guided stereotactic implantation of Ir192 in the treatment of malignant astrocytomas. During the past year, 16 patients have been implanted with two to four catheters in the residual enhancing portion of their tumor. These patients represent 50% of our total experience with the CT compatible Leksell frame. Each catheter contains three to six high intensity (2.0 to 2.5 mg Ra equivalent) seeds with 0.5 cm separation between the sources. The total activity of Ir192 per implant has been 30-65 mg radium equivalent. In the 16 patients, 49 catheters have been placed, an average of three targets calculated per patient and no targets have been missed. The radiation exposure to personnel has been surveyed in detail and drops off to less than 2 mr/h six feet from the patient when our custom-built radiation shield is employed. We have reserved permanent implantation of I125 for patients with tumors in unusual locations (e.g. pineal) or for individuals with slowly growing non-gliomatous lesions (i.e. meningioma). The tumor volumes have ranged from 12-120 cm3. Unique aspects of our implant procedure include the use of a Leksell frame already adapted to the GE-8800 scanner, the use of pre- and post-implant computerized treatment planning programs to determine the dose distribution profiles and the use of adjustable metal collars crimped to the outer catheters to provide ease of insertion, uniform pre-implant catheter length, and protection against source migration. Two of our patients have suffered from subacute radiation reactions, primarily due to delayed cerebral edema and both of these cases have largely resolved.(ABSTRACT TRUNCATED AT 250 WORDS)

Patient immobilization during CT for treatment planning of head and neck cancer.

Immobilizers are described that have been used during computed tomography (CT) to ensure reproducibility of patient position during all phases of radiation treatment planning and delivery. The immobilizer causes no degradation or artifact on CT images; hence, the value of the images in radiation treatment planning is not compromised.

Palliative half-body irradiation. Single and fractionated doses.

Systemic half-body irradiation (HBI) has been used extensively for the palliation of cancer pain. It has also been tried as an adjuvant therapy in patients with advanced locoregional tumors with a high propensity to disseminate and as consolidation therapy after primary systemic treatment. The limitations and toxicity of this technique have been studied extensively. Single doses of 600 rad to the upper half-body (UHB) and 800 rad to the lower half-body (LBH) have been found to achieve excellent palliative responses with an acceptable rate of complications. In order to determine the feasibility of increasing the dose of radiation delivered, a pilot study was conducted at the University of Maryland. Forty-four patients received palliative HBI. Of these, the first 36 patients received single doses to the UHB, mid-body (MB), or LHB using doses of 600 rad to the UHB and 800 rad to MB and LHB. The last consecutive eight patients received two fractions of 400 rad each, given 2-3 weeks apart. The pain response achieved by each group is similar; single dose achieved 84% complete and partial responses vs. the fractionated group, which achieved 87% complete and partial responses. The main difference between the two groups was the time necessary to achieve a response. The single dose group achieved improvement of their symptoms in 24-48 hours in approximately 70% of the patients who responded. The fractionated group achieved symptomatic response after the second dose of irradiation was given. The toxicity of both groups was similar. The acute radiation syndrome after half-body irradiation was controlled with a premedication program. Hematological toxicity was similar in both groups, and no cases of fatal radiation pneumonitis were seen. At the present time, it seems feasible to proceed with other fractionation schemes in order to try to increase the total dose delivered.

Carcinoma of the floor of the mouth: a 20-year experience.

From 1955 to 1975, 116 patients with squamous cell carcinoma of the floor of the mouth were primarily treated by irradiation in the Department of Radiation Oncology, University of Maryland at Baltimore. Of these, 93 evaluable patients yielded loco-regional control rates of 83, 85, 42 and 21% for Stages I-IV, respectively. A palisading technique of radium needle implants was used, either alone or combined with external beam therapy, for early tumors (Stages I-II). Similar control rates were achieved by these two techniques: 13/14 for interstitial irradiation alone and 16/24 for combined interstitial and external irradiation. In selected early cases (Stages I-II), errors in staging were minimized by the systematic use of a needle biopsy of the submaxillary triangle for suspicious submaxillary swellings. Patients with early lesions and truly negative nodes (N0) only received irradiation to the primary tumor bed. No subsequent nodal neck failures have occurred in 13 of such patients. The overall complication rate for the entire series was 17% with only 8 patients requiring surgery. No differences in complication rates were found among the treatment modalities employed. The distribution of lymph nodal involvement by anatomical level, correlation of histological differentiation or tumor aggressiveness at presentation, the dosimetric analysis of the palisading interstitial technique, the spread and failure patterns and other observations are discussed.

Radium needles implant in the treatment of extensive vaginal involvement from cervical carcinoma. A dosimetry appraisal.

An appraisal of the dosimetry of a modified brachytherapy approach is presented for improving the local control of extensive vaginal involvement from carcinoma of the cervix. This approach incorporates radium needles implant to the vaginal disease in conjunction with the usual routine intracavitary radium application. The aim of the interstitial implant is specifically to supplement the dose to the vaginal disease from the intracavitary application. Our procedure for accomplishing this boost in the dose to the vagina depends on the location, extent and thickness of the vaginal lesion following external beam irradiation of the whole pelvis. An increase of greater than 50 per cent in the dose to the vaginal disease is gained by this combination intracavitary/implant approach which has been used in a variety of cases covering virtually all pertinent stages of cervical carcinoma. Discussion of the dosimetry of example cases is presented to demonstrate the value of combining interstitial and intracavitary therapy for this specific clinical application.

Removable high intensity iridium-192 brain implants. Technique and in vivo measurements in canine brain.

A preclinical evaluation of the technical details and dosimetry for temporary high intensity 192Ir brain implants is presented. The canine brain was used for this quality assurance study in which direct in vivo dose measurements were done by thermoluminescent dosimetry (TLD rods). Precise and reproducible positioning of the TLD rods and 192Ir ribbons were assured by simple accessories which can be utilized in the clinical situation. The neurosurgical procedure for this non-routine interstitial implant of the brain, suitability of type and size of afterloading cannulas and facility for firmly anchoring them to the scalp, and comparison of measured doses with computer-predicted values are details assured by the canine study. Agreement between the in vivo determination and computer-generated doses was consistently in the range 2-5%. Data derived from this preclinical evaluation are currently used in both stereotactic and non-stereotactic brain implants at our institution. Details are presented for the implant procedure, dose measurements and brachytherapy planning for multiple ribbons. The latter incorporates direct interaction on computed tomography (CT) images for a hypothetical patient case.

Adenocarcinoma arising in female urethral diverticulum.

Cancer arising from a female urethral diverticulum is rare, and because of its rarity, a review of the medical literature reveals significant nonuniformity in its management. We report an additional 2 cases of this disease, one of which has an even rarer feature of being mucin-producing. The management of our 2 cases is presented in detail and in line with the management of female urethral cancer. From our extensive literature search, diverticulectomy alone showed poor results with the highest rate of recurrence (67%). Extensive surgery, either in the form of cystourethrectomy or anterior exenteration, offered results comparable with those of combined therapy (diverticulectomy and full course of irradiation for early cases; preoperative irradiation followed by cystourethrectomy for late cases). Individualization of radiation treatment and cooperative effort between urologist and radiation oncologist are essential if best results are to be achieved.

Radiation management of advanced nasopharyngeal cancer.

During the period from 1957-1976, 70 patients with advanced malignant tumors of nasopharynx were treated by irradiation in the Department of Radiation Therapy, University of Maryland Hospital. Forty-nine patients were treated with curative intent and 21 patients with palliative purpose. Of 49 patients treated for cure, 22 (45%) survived disease-free for at least 5 years. Local control was achieved best (92%) by combined treatment, external beam and brachytherapy. Factors responsible for local control and disease-free survival, appear to be related to clinical staging (primary and nodal disease), cell types and treatment used. In spite of aggressive radiation treatment for advanced cases (Stages III and IV), distant disease is still a major problem and will necessitate further trial by combined chemotherapeutic treatment with irradiation. This article highlights the results and failures of the technique of the irradiation, both external and brachytherapy. It is suggested that aggressive radiation treatment using a combined approach (external beam and brachytherapy, whenever possible) be done in all cases for cure. Palliative treatment can only offer a short-term symptom-free status in 72% of all cases treated.