Use of body scanner in radiotherapy treatment planning

Abstract

CT body scans obtained on 98 patients before, during, and after radiotherapy were evaluated for their utility in radiotherapy treatment planning and in follow-up after radiotherapy. Twenty-two patients were studied after irradiation. Four received additional treatment, and continuing or platlned treatment was withheld from another four on the basis of CT data. Tumor extent was clearly delineated on CT scan in 48/76 cases (63%), suggestive in 25/76 (33%), and not seen in only three (4%). Utilizing CT data relative to all other available tests, in 75 patients, total treatment volume was altered in 34 (45%), tumor coverage was marginal or inadequate in 35 (47%), and volume of normal tissue irradiated was changed in 34 (45%). CT scan data was judged essential for treatment planning in 41, or 55%, of patients studied. Unsuspected areas of tumor involvement were seen in 32 of 75 cases (43%). Use of the CT scan as a patient contour for radiotherapy treatment planning and alternative techniques for inputting the CT data to treatment planning computers are discussed. A simple inexpensive device to accomplish this is described. Speculations are made regarding the impact of CT scanners on transverse axial tomography units and treatment simulators as well as the potential application of the technique in brachytherapy dose computation.

Computed tomography in carcinoma of the rectum

“…The accurate position of the malignancy and the regional lymph nodes, and the topographic relationship with neighboring organs are well identified according to the positioning of the patient [1, 3,4,6,10,12]. Based on the transverse sections of the pelvic area, the target volume for irradiation therapy is calculated in an optimal way.…”

Heavy Charged Particle Radiotherapy

“…Computerized tomography plays an even more essential role in charged particle radiotherapy, where CT is utilized in target volume definition, quantitation of inhomogeneities, portal design, and placement and post-therapeutic evaluation of tumor response. Studies have shown that cr is an important adjunct in tumor volume definition (31,50) and that without this diagnostic aid, marginal and geometric misses of the target volume occur in over 40% of cases. Proper tumor volume definition is of obvious benefit to both conven tional and charged particle radiotherapy.…”

Evaluation of the influence of breathing on the movement and modeling of lung tumors

“…These 2 studies quantified for the first time the degree of tumor motion in NSCLC. The problem with radiographs and fluoroscopy, however, is that compared to CT, they are not as accurate at target volume delineation in lung cancer (10,11).…”