Mary L. Graham

A METHOD TO ANALYZE 2-DIMENSIONAL DAILY RADIOTHERAPY PORTAL IMAGES FROM AN ON-LINE FIBER-OPTIC IMAGING SYSTEM

On-line radiotherapy imaging systems allow convenient treatment verification and generate a wealth of data. Quantitative analysis of data will provide important information about the nature of treatment variations. Using an inhouse fiber-optic imaging system to acquire daily portal images for five patients, we have developed a method to analyze the cumulative positional variation of blocks in the 2-dimensional images. For each beam arrangement used to treat a particular patient, a reference portal image was established. All other images for that patient were registered with respect to the anatomical landmarks visible on the reference image. Two-dimensional frequency distributions describing the overlap of the blocks during the course of treatment were then calculated and superimposed on the reference image. Results of the analysis show positional and quantitative information about the daily variation in block placement, and appeared to be site-dependent. Long term verification studies using on-line imaging systems will be important in the understanding of treatment uncertainties.

Design of a fully integrated three-dimensional computed tomography simulator and preliminary clinical evaluation

PURPOSE We describe the conceptual structure and process of a fully integrated three-dimensional (3-D) computed tomography (CT) simulator and present a preliminary clinical and financial evaluation of our current system. METHODS AND MATERIALS This is a preliminary report on 117 patients treated with external beam radiation therapy alone on whom a 3-D simulation and treatment plan and delivery were carried out from July 1, 1992, through June 30, 1993. The elements of a fully integrated 3-D CT simulator were identified: (a) volumetric definition of tumor volume and patient anatomy obtained with a CT scanner, (b) virtual simulation for beam setup and digitally reconstructed radiographs, (c) 3-D treatment planning for volumetric dose computation and plan evaluation, (d) patient-marking device to outline portal on patients skin, and (e) verification (physical) simulation to verify portal placement on the patient. Actual time-motion (time and effort) recording was made by each professional involved in the various steps of the 3-D simulation and treatment planning on computer-compatible forms. Data were correlated with the anatomic site of the primary tumor being planned. Cost accounting of revenues and operation of the CT simulator and the 3-D planning was carried out, and projected costs per examination, depending on case load, were generated. RESULTS Average time for CT volumetric simulation was 74 min without or 84 min with contrast material. Average times were 36 min for contouring of tumor/target volume and 44 min for normal anatomy, 78 min for treatment planning, 53 min for plan evaluation/optimization, and 58 min for verification simulation. There were significant variations in time and effort according to the specific anatomic location of the tumor. Portal marking of patient on the CT simulator was not consistently satisfactory, and this procedure was usually carried out on the physical simulator. Based on actual budgetary information, the cost of a volumetric CT simulation (separate from the 3-D treatment planning) showed that 1500 examinations per year (six per day in 250 working days) must be performed to make the operation of the device cost effective. The same financial projections for the entire 3-D planning process and verification yielded five plans per day. Some features were identified that will improve the use of the 3-D simulator, and solutions are offered to incorporate them in existing devices. CONCLUSIONS Commercially available CT simulators lack some elements that we believe are critical in a fully integrated 3-D CT simulator. Sophisticated 3-D simulation and treatment planning can be carried out in a significant number of patients at a reasonable cost. Time and effort and therefore cost vary according to the anatomic site of the tumor being planned and the number of procedures performed. Further efforts are necessary, with collaboration of radiation oncologists, physicists, and manufacturers, to develop more versatile and efficient 3-D CT simulators, and additional clinical experience is required to make this technology cost effective in standard radiation therapy of patients with cancer.

INTERFRACTION INTERVAL DOES NOT AFFECT SURVIVAL OF PATIENTS WITH NON-SMALL CELL LUNG CANCER TREATED WITH CHEMOTHERAPY AND/OR HYPERFRACTIONATED RADIOTHERAPY: A MULTIVARIATE ANALYSIS OF 1076 RTOG PATIENTS

PURPOSE It was observed by Jeremic et al. that a shorter interfraction interval (IFI) was associated with an improved survival in patients (pts) with locally advanced non-small cell lung cancer (NSCLC) treated with hyperfractionated radiation therapy (HFX-RT), with or without chemotherapy (CT). Our analysis was undertaken to verify this hypothesis. METHODS AND MATERIALS Records of patients treated on 5 Radiation Therapy Oncology Group (RTOG) studies were reviewed, and an actual IFI, defined as a mean of all daily IFIs, was calculated. RT dose was 1.2 Gy BID to 69.6 Gy. The relationship between the length of IFI and the median survival time and incidence of esophagitis was investigated. RESULTS In 682 pts eligible for this analysis, a full dose of RT was delivered and at least 90% of all daily IFIs were available. The actual mean IFI was as follows: 4-4.9 h in 51% of pts; 5-5.9 h in 17%; 6-6.9 h in 28% and 7-8 h in 4%. In multivariate analysis, only lack of weight loss, use of CT, low nodal stage and good KPS, but not IFI (4-6 h vs. 6-8 h) were associated with an improved survival for all pts (p values: <0.0001; <0.0001; 0.006; 0.006, and 0.73, respectively), as well as for HFX-RT only pts. For the CT-HFX-RT pts, not enough data points are available for a meaningful analysis. Length of IFI did not influence the incidence of Grade 3 or higher esophagitis (p = 0.82), but use of CT was associated with a 12-fold greater risk of developing severe esophagitis (p < 0.0001). CONCLUSION Length of IFI (4-6 h vs. 6-8 h) did not influence survival and acute complications incidence in pts with NSCLC treated in RTOG studies with HFX-RT to 69.6 Gy. Previously identified factors, such as use of CT, minimal weight loss, good KPS and low nodal stage, were confirmed again to be associated with a favorable prognosis in a multivariate analysis. Use of CT was associated with a 12-fold greater risk of developing severe esophagitis than HFX-RT alone. It appears that an IFI of 4-8 hr is acceptable in clinical practice for pts with NSCLC, treated with HFX-RT.

O-93 Radiotherapy patterns of care study in lung carcinoma

PURPOSE For the first time, a lung Patterns of Care Study was conducted to determine the national patterns of radiation (RT) practice in patients treated for nonmetastatic lung cancer in 1998 to 1999. MATERIALS AND METHODS A national survey of randomly selected RT institutions in the United States was conducted using two-stage cluster sampling, stratified by practice type. Patients with nonmetastatic lung cancer (Karnofsky performance score [KPS] > or = 60), who received RT as definitive or adjuvant therapy, were randomly selected. To determine national estimates, sample size was weighted by the relative number of institutions per strata and the number of patient records reviewed per the number of patients eligible. Accordingly, 42,335 patient records from 58 institutions were reviewed by trained research associates. The unweighted sample size (or number of patients) was 541. RESULTS The histologies were small-cell lung cancer (SCLC) in 14.5% of patients versus non-small-cell lung cancer (NSCLC) in 85.5% of patients. The median age was 67 years (range, 29 to 92 years); 61% of patients were male, and 38% were current smokers. Bone scans and brain imaging were not obtained in 34% and 52% of clinical stage (CS) III NSCLC patients, respectively. Regarding treatment strategies, for SCLC and CS III NSCLC, chemotherapy plus RT was used significantly more than RT alone (P <.05); in CS I NSCLC, RT alone was the primary treatment (P <.05). Overall, 58% of patients received systemic therapy. On multivariate analysis, factors correlating with increased use of chemotherapy included younger age, histology (SCLC > NSCLC), increasing CS, increasing KPS, and lack of comorbidities. Only 3% of all patients were treated on prospective clinical trials. CONCLUSION This study establishes the general patterns of care for lung carcinoma in RT facilities within the United States. As supported by clinical trials, patients with limited-stage SCLC and CS III NSCLC received chemotherapy plus RT more than they received RT alone. Further improvements in staging, smoking cessation, and increased accrual to clinical trials must be encouraged.