Analysis of localization errors in the definition of the mantle field using a beam's eye view treatment-planning system.

PURPOSE: Reports of the treatment of Hodgkin's disease (HD) with radiotherapy using the mantle field technique have demonstrated that coverage of disease by the field blocks significantly compromises outcome. It is our hypothesis that the availability of computerized tomography images reduces the incidence of localization error, and that the use of beam's eye view treatment planning techniques may further improve localization. The purpose of this report is to assess the possible contribution of a three-dimensional treatment-planning system to tumor localization and mantle block drawing in patients with HD. MATERIALS AND METHODS: We evaluated the localization error rate of four experienced radiation oncologists as they drew the lung blocks for the mantle field. The analysis included 16 patients treated with mantle fields in our department between 1989 and 1991. In each case our computerized three-dimensional treatment planning system was used to generate a beam's eye view display of tumor volumes. Simulation radiographs for all 16 patients were overlaid with acetate film, and lung blocks were drawn by clinicians using only the simulation radiographs for reference. The process was repeated with the thoracic CT scans available for reference. The mantle block contours for each trial were then superimposed upon the beam's eye view plots of tumor volumes. The beam's eye view plot was our benchmark for the evaluation of errors of tumor localization. Localization errors were defined as touching or overlap of the shielding blocks onto tumors. RESULTS: There was a high degree (p < 0.0003) of consistency in scoring across all pairing of clinicians and the results from all four were polled for the analysis. The overall error rate using the simulation radiographs alone was 18%. The rate was significantly lower (13%) when the CT images were available (p = 0.038). The axillary region had the highest localization error rate (41.7% with CT available and 27.1% with CT available) and the superior mediastinum had the lowest error rate (10.7% without CT, 8.5% with CT). Compared with a system such as beam's eye view, which could reduce the localization error rate to zero, the error rate with CT scans available is still significant [95% confidence interval (CI = 10-17.1%)]. Localization errors were more likely with increasing tumor size when CT scans were not available (p = 0.029). A similar trend was not seen when CT scans were available (p = 0.2). In a multivariate analysis, the use of CT scans predicted for reduced localization error rate (p = 0.03). Tumors in the axilla and inferior mediastinum had a greater relative risk than those in the superior mediastinum (p = 0.0001) CONCLUSION: The availability of CT imaging offers an advantage in the outlining of the mantle field in the treatment of Hodgkin's disease. When the error rate is evaluated using a beam's eye view treatment planning system, a significant proportion of tumors may be overlapped by the outlined mantle blocks even when CT images are available for reference. The use of beam's eye view treatment planning in mantle field definition, especially for tumors in the axillary region, may reduce the incidence of geographic misses.

Three-dimensional treatment planning of intracavitary gynecologic implants: analysis of ten cases and implications for dose specification.

PURPOSE: Results of 3-dimensional treatment planning for ten intracavitary gynecologic implants and implications for dose specification are presented. METHODS AND MATERIALS: Using a computed tomographic (CT) compatible intracavitary applicator we have performed CT scans during gynecologic brachytherapy in 10 cases. A CT-based treatment planning system with 3-dimensional capabilities was used to calculate and display dose in three dimensions. Conventional point doses including the estimated bladder and rectal maximum doses and dose to Point A were acquired from orthogonal simulation films. CT maximum bladder and rectal doses and minimum cervix doses were ascertained from isodose lines displayed on individual CT images. Dose volume histograms for the bladder, rectum and cervix were generated and used to obtain volume of the cervix target volume receiving less than the prescribed dose and the volume of bladder and rectum receiving more than the orthogonal maximum doses. The 5 cc volume of bladder and rectum receiving the highest dose were also calculated. RESULTS: Average values of CT point doses and volumes are compared with the traditionally obtained doses. As demonstrated by others, much higher bladder and rectal doses are found using the CT information. The minimum dose to the cervix target volume is lower than the dose to Point A in each case. CT maximum bladder and rectum and minimum cervix target doses may not be the best index doses to correlate with outcome because of the small volumes receiving the dose. CONCLUSION: We hypothesize that clinically useful bladder, rectal and cervix target volume doses will include volume information which is obtainable with dose volume histogram analysis.

Total scalp treatment of mycosis fungoides: the 4 x 4 technique.

PURPOSE: A technique for treating mycosis fungoides confined to the scalp using a method known as the 4 x 4 technique is presented. METHODS AND MATERIALS: Uniform dose distribution on the scalp and acceptable "hot spots" along five match lines is accomplished by using four sets of four fields (i.e., 4 x 4) on the patient. Precise and reproducible patient and field alignment was accomplished with a solid thermoplastic mask, which is the surface on which match lines are drawn. In-vivo dosimetry (thermoluminescent dosimeters and film) are easily attached to the mask which also provides a portion of the 7 mm bolus used to shift the characteristic 6 MeV electron depth dose toward the skin surface. RESULTS: In-vivo dosimetry demonstrated that single fraction match line doses are within 25% to 30% of central axis dose. Shifting these match lines to four locations reduces these "hot spots" to satisfactory levels (less than 120%). Three patients have been treated with this technique and each patient continues to have a complete clinical response at 14 to 21 months post treatment. In addition, each patient has excellent cosmetic results with no evidence of acute or chronic side effects at the match lines. CONCLUSION: The 4 x 4 technique has proven to be useful in the treatment of mycosis fungoides confined to the scalp.

Primary treatment of stage III ovarian carcinoma with sequential chemotherapy and whole abdominal radiation therapy.

A prospective phase II clinical treatment trial of 13 patients with previously untreated optimal surgically resected (< or = 1 cm stage III ovarian carcinoma was conducted at the University of Michigan Hospitals. The treatment regimen after surgical resection consisted of chemotherapy followed by whole abdomen and pelvic radiation therapy. Chemotherapy consisted of four cycles of 50 mg/m2 cisplatin and 1000 mg/m2 cytoxan. This was followed by whole abdomen radiation therapy with a planned total dose of 30 Gy to the whole abdomen and then a 20-Gy boost to the pelvis. Six of 13 patients received a paraaortic radiation boost. There was minimal acute toxicity, but delayed toxicity was encountered with 38% of patients developing a bowel obstruction. Nine patients had reassessment laparotomy: 5 second-look laparotomies and 4 laparotomies for bowel obstruction. Two of these 9 patients died of septic complications after surgery. Nine patients died with disease, 1 patient is alive with advanced disease, and only 3 patients are alive with no evidence of disease. Actuarial 3-year survival and progression-free interval was 26 and 20%, respectively. Primary treatment consisting of sequential chemotherapy and whole abdomen radiation in the dose and scheme utilized did not improve the survival over what could be expected utilizing one of these treatments alone. It was associated with increased delayed toxicity.

Continuous infusion of low-dose 5-fluorouracil and radiation therapy for poor-prognosis squamous cell carcinoma of the uterine cervix.

Ten patients with squamous cell carcinoma of the cervix metastatic to periaortic lymph nodes were treated with external-beam radiation therapy and synchronous infusion of intravenous 5-fluorouracil (5-FU) chemotherapy at doses of 350 mg/m2/day. The overall response rate was 90% with four complete responses (CR) and five partial responses (PR). The median duration of response was 11.8 months for CRs and 3.6 months for PRs. Toxicity was tolerable, with gastrointestinal symptoms and myelosuppression being noted most frequently. No patient experienced life-threatening toxicity. Median survival was 7.6 months, with only one patient being alive and free of disease at 2 years. In this pilot study we were unable to demonstrate a beneficial effect of continuous infusion of low doses of 5-FU chemotherapy concurrent with radiation therapy when compared to conventional radiotherapy in patients with advanced squamous cell carcinoma of the cervix.

Magnetic resonance imaging during intracavitary gynecologic brachytherapy.

The cases of three patients, two with Stage III-B and one with Stage II-B carcinoma of the cervix, are cited to illustrate specific advantages of magnetic resonance (MR) imaging over computed tomography (CT) during intracavitary gynecologic brachytherapy. CT and MR were performed during the first of two intracavitary implants. To obtain artifact-free images with the intracavitary implant in place, a CT- and MR-compatible Fletcher system applicator was used. Although CT failed to differentiate the cervical tumor clearly from surrounding tissues, the area of pathology could be identified on MR by comparing the T1-weighted (T1W) and T2-weighted (T2W) images. Cervical tumors typically exhibit low-signal intensity on T1W and high-signal intensity on T2W scans, whereas paracervical soft tissues demonstrate high intensity on both T1W and T2W images. This contrast permits the size, location, and paracervical involvement of the tumor to be defined by MR. Multiplanar MR images obtained during the patients' intracavitary brachytherapy help demonstrate the actual anatomic relationship between the tumor and the applicator. Isodose distributions displayed on these images show that, in two cases, the tumor margin extended beyond the prescribed isodose line. Thus, MR may prove to be a clinically useful reference during intracavitary brachytherapy for ascertaining radiation dose to actual tumor volume.

The use of CT-based 3-D anatomical modeling in the design of customized perineal templates for interstitial gynecologic implants.

A system for preplanning interstitial treatment of gynecologic malignancies with a CT-based 3-dimensional planning system is presented. The preplan produces a custom template design that optimizes catheter placement. The procedure begins with a CT scan with a vaginal cylinder and blank template in place. Contours of the anatomic structures of interest, cylinder, and template are entered into the system, and 3-D surfaces are generated. The first view evaluated is oriented in a "cylinder's-eye view," which shows the path of the catheters placed parallel to the cylinder. In most cases this path to the tumor is obstructed by the pubic bones and bladder. By rotating the view posteriorly, the catheters can travel under the symphysis and bladder to the tumor. Once the optimum angle for visualization of the tumor has been determined, an array of catheters is designed to optimize the dose to the tumor. This array includes the special distribution in the oblique plane as well as the depth of insertion for each catheter. The design is then used in drilling the appropriate guide holes in the template. Orthogonal film dosimetry as well as CT verification of source placement will be compared to the preplan distribution.

Treatment planning issues related to prostate movement in response to differential filling of the rectum and bladder.

Conventional stimulation for patients with localized prostatic carcinoma often includes opacification of the dose limiting adjacent normal tissues. However, CT-based treatment planning is performed with the bladder and the rectum naturally filled or emptied. These latter conditions more closely approximate those in place at treatment Comparison of these CT-based treatment plans to simulator films taken with the rectum and bladder opacified yielded indirect evidence of movement of the prostate gland by 0.5 cm or more in 31 of 50 consecutive patients. The range of motion was 0 to 2 cm with an average of 0.5 cm (1.0 cm in the 31 patients). Six additional patients (five with local recurrence following I-125 seed implantation) were analyzed separately using CT scans. Registered CT images (3 mm slices) taken with the rectum and bladder full and/or empty provided direct evidence of prostate movement in 3 of the 6 patients. The dosimetric consequences of this movement are demonstrated using 3-dimensional dose distributions.

A CT-compatible version of the Fletcher system intracavitary applicator: clinical application and 3-dimensional treatment planning.

A new acrylic version of the familiar Fletcher intracavitary applicator, the Ann Arbor (AA) applicator, has been developed. This new device eliminates the problem of "streak" artifacts on CT images, but unlike other plastic applicators the ability to shield portions of the bladder and rectum is retained through the use of tungsten alloy shields which are afterloaded with the radioactive sources. To minimize changes in placement geometry and to take advantage of the wide clinical experience with the Fletcher system, the new applicator nearly duplicates the physical dimensions of the Fletcher applicator. With the Ann Arbor applicator in place, dummy sources are easier to locate on standard radiographic simulations. CT scans are free of artifact and provide clear, detailed visualizations of cross-sectional anatomy. The new applicator thus allows CT images to be used to their potential in evaluating crucial anatomic relationships and in performing 3-D dosimetry with dose volume analysis. Using a treatment planning system with 3-D capabilities, solid surface graphic display of applicator, cervix, rectum, bladder, and treatment isodose volume has been performed. In addition, dose volume histograms can be generated to obtain precise measurements of the volume of cervix, rectum, or bladder receiving specified doses.

Hodgkin's disease in homosexual men with generalized lymphadenopathy.

PIP: The authors present 4 cases of Hodgkin's disease developing in homosexual men with persistent, generalized lymphadenopathy. Laboratory abnormalities associated with the acquired immunodeficiency syndrome (AIDS) and the lymphadenopathy syndrome were present in these patients. In 2 patients, diagnosis of lymphadenopathy syndrome preceded the diagnosis of Hodgkin's disease by 2-3 years; in the other 2, the 2 conditions were noted simultaneously. 2 patients had nodular sclerosing Hodgkin's disease, while the other 2 had mixed cellularity disease. All patients presented with clinical stage III or IV Hodgkin's disease. 2 patients in this group have died: 1 of progressive Hodgkin's disease with evidence of atypical myobacterial infection, and 1 with no evidence of Hodgkin's disease but with AIDS-related infections. The lymphadenopathy syndrome has a presentation similar to that of Hodgkin's disease: lymphadenopathy often accompanied by malaise, fever, night sweats, weight loss, and splenomegaly. When a homosexual man presents with painless adenopathy, with or without constitutional symptoms, the potential diagnosis of Hodgkin's disease or other malignancy should be considered in addition to lymphadenopathy syndrome. Evaluation by lymph node biopsy is advisable. The natural history of Hodgkin's disease in patients at risk for AIDS may be altered to a more aggressive form. Unusual features of Hodgkin's disease observed in this group of patients included presentation with stage IV disease, cutaneous Hodgkin's disease, and bone marrow but no splenic involvement. The effects of the treatment modes used for Hodgkin's disease in homosexual patients should be evaluated for their effect on the risk of AIDS.^ieng

Effects of myocardial infarction on perioperative cardiac complications.

Of 1104 consecutive noncardiac operations on 981 patients using general anesthesia, 63 were performed on 53 patients who had had a previous myocardial infarction. Patients with a previous infarct were compared to those with no prior infarct to determine the influence of a previous infarct on perioperative cardiac complications. Two of the 53 patients with a previous myocardial infarction (3.8%) had perioperative myocardial infarction, compared to 0.4% (4/928) of patients with no prior history of myocardial infarction (P less than 0.05). Ventricular tachycardia (P less than 0.05) and cardiac death (P less than 0.01) were more frequent in patients with a previous myocardial infarction compared to those with no prior infarct. All patients with a previous myocardial infarction who developed cardiac complications underwent vascular procedures (P less than 0.005) and were over 77 years of age. The two patients who reinfarcted experienced intraoperative hypotension (P less than 0.05). Fourteen of the 53 patients with a history of a myocardial infarction (26.4%) had previous coronary artery bypass surgery; no perioperative cardiac complications occurred in these patients.

Squamous cell carcinoma of the soft palate.

We performed a retrospective study of 106 patients with carcinoma of the soft palate who were treated at two university hospitals. Computer analysis using a new interactive data base program called MING was made to determine Berkson-Gage survival and Gehan tests of statistical significance. Statistically significant associations with an increased survival included the following: smaller lesions, a clinically negative neck examination. well- and moderately well-differentiated histopathologic features, radiation therapy dose of less than or equal to 6,300 rads, absence of a simultaneous primary, and surgical salvage. No statistically significant differences were seen with age, sex, stage, or the number of days during which patients were treated with radiation therapy. There appears to be a need for a prospective, multi-institutional, randomized therapy study to solidify treatment policy. Consideration should be given to combine surgery-radiation vs radiation therapy alone.