H S Glazer

THREE-DIMENSIONAL RADIATION TREATMENT PLANNING STUDY FOR PATIENTS WITH CARCINOMA OF THE LUNG

PURPOSE Several reports in the literature suggest that local-regional control and possibly survival could be improved for inoperable nonsmall cell lung cancer if the radiation dose to the target volume could be increased. Higher doses, however, bring with them the potential for increased side effects and complications of normal tissues. Three-dimensional treatment planning has shown significant potential for improving radiation treatment planning in several sites, both for tumor coverage and for sparing of normal tissue from high doses of radiation and, thus, has the potential of developing radiation therapy techniques that result in uncomplicated local-regional control of lung cancer. We have studied the feasibility of large-scale implementation of true three-dimensional technologies in the treatment of patients with cancers of the thorax. METHODS AND MATERIALS CT scans were performed on 10 patients with inoperable nonsmall cell lung cancer to obtain full volumetric image data, and therapy was planned on our three-dimensional radiotherapy treatment planning system. Target volumes were determined using the new ICRU nomenclature--Gross Tumor Volume, Clinical Target Volume, and Planning Target Volume. Plans were performed according to our standard treatment policies based on traditional two-dimensional radiotherapy treatment planning methodologies and replanned using noncoplanar three-dimensional beam techniques. The results were quantitatively compared using dose-volume histograms, dose-surface displays, and dose statistics. RESULTS Target volume delineation remains a difficult problem for lung cancer. Defining Gross Tumor Volume and Clinical Target Volume may depend on window and level settings of the three-dimensional radiotherapy treatment planning system, suggesting that target volume delineation on hard copy film is inadequate. Our study shows that better tumor coverage is possible with three-dimensional plans. Dose to critical structures (e.g., the heart) could often be reduced (or at least remain acceptable) using noncoplanar beams even with dose escalation to 75 to 80 Gy for the planning volume surrounding the Gross Target Volume. CONCLUSION Commonly used beam arrangements for treatment of lung cancer appear to be inadequate to safely deliver tumor doses of higher than 70 Gy. Although conventional treatment techniques may be adequate for tumor coverage, they are inadequate for sparing of normal tissues when the prescription dose is escalated. The ability to use noncoplanar fields for such patients is a major advantage of three-dimensional planning. This capability led to better tumor coverage and reduced dose to critical normal tissues. However, this advantage was achieved at the expense of a greater time commitment by the treatment planning staff (particularly the radiation oncologist) and a greater complexity of treatment delivery. In summary, three-dimensional radiotherapy treatment planning appears to provide the radiation oncologist with the necessary tools to increase tumor dose, which may lead to increased local-regional control in patients with lung cancer while maintaining normal tissue doses at acceptable tolerance levels.

Computed tomography of renal lymphoma with ultrasound correlation.

The computed tomography (CT) and ultrasound findings in 18 patients (35 kidneys) with non-Hodgkin lymphoma involving the kidneys are presented. Renal involvement was bilateral in 13 patients. The most common presentation was that of multiple intraparenchymal nodules (15 kidneys). Other types of involvement included direct invasion from contiguous retroperitoneal lymph node masses (nine kidneys), solitary renal masses (five kidneys), and diffuse infiltration (two kidneys). On CT most of the lesions were of homogeneous tissue density. Ultrasonographically the renal masses were hypoechoic. We believe that CT is the procedure of choice for the detection and follow-up of renal lymphoma.

MR imaging of intraspinal extension of neuroblastoma.

The CT and magnetic resonance (MR) findings in two children with intraspinal extension of mediastinal neuroblastoma are described. The potential of MR to obviate the need for myelography is discussed.

Superior diaphragmatic lymph nodes: CT assessment.

The normal CT appearance of the superior diaphragmatic (also called cardiophrenic angle or pericardial) lymph node group was assessed in 39 adult patients who were free of diseases known to involve lymph nodes. In 15 patients there were 27 ovoid opacities, corresponding to known lymph node sites, namely in the anterior portion of the diaphragm; all except one opacity measured <5 mm in diameter. Superior diaphragmatic lymph nodes ≥6 mm in diameter were observed in 30 of 190 patients with diseases known to be associated with lymphadenopathy. All but one of these patients had a pathologically proven malignant neoplasm, with bronchogenic carcinoma the most common etiology.

Imaging Evaluation of Obstructive Atelectasis

Segmental or lobar atelectasis is a common radiographic finding in patients with bronchial obstruction. Although in many cases the presence and cause of atelectasis can be ascertained from the plain chest radiograph, computed tomography (CT) often provides valuable additional information, particularly with regard to the precise location and extent of the obstructing process. CT also can be used to differentiate between benign and malignant causes of obstructive atelectasis. After administration of intravenous contrast material, CT may distinguish a proximal obstructing tumor from collapsed lung or adjacent mediastinal structures. In some patients, magnetic resonance imaging (MRI) can provide comparable and/or complementary information. In this article, we review the major applications of CT and MRI, as well as the capabilities and limitations of both techniques, in the evaluation of patients with obstructive atelectasis.

Digital mobile radiography

A storage phosphor digital imaging system has been used to perform virtually all of an increasing number of mobile (portable) projectional roentgenographic examinations in a busy hospital. Approximately 130 such studies are done per day, of which about 110 are chest examinations. The processing unit suffices to keep pace with peak activity in the radiology department. This technique has decreased the repeat rate for portable anteroposterior chest radiographic examinations from 4.5% to less than 1% and has resulted in an even more dramatic reduction in the rate for lateral or decubitus chest examinations as well as for studies of the abdomen and those done in the operating room. The diagnostic accuracy and confidence level achieved in interpreting the complementary pair of digital images has been equivalent to or has exceeded that obtained with conventional mobile analog film-screen radiographs.

NMR imaging of pulmonary arteriovenous fistulae .

The nuclear magnetic resonance (NMR) imaging of pulmonary arteriovenous fistulae is reported, and the value of NMR in separating vascular from nonvascular lesions in the lung and mediastinum is discussed.

Traumatic perforation of the pyriform sinus: CT demonstration.

Hypopharyngeal perforation secondary to tracheal intubation is a rare and serious complication. Radiographic evaluation is helpful when the clinical diagnosis is not obvious. In one such case CT demonstrated the site of perforation and its extension into the superior mediastinum, facilitating the subsequent surgical approach.