Radiosurgical management of brain metastases.

Stereotactic radiosurgery (SRS) should be considered in the comprehensive treatment paradigm for all patients with brain metastases. This technique has proven benefits for local tumor control in individuals with as many as 4 lesions, and when combined with structured radiographic follow-up, will likely preserve a better quality of life for appropriately selected patients. Institutions and physicians treating patients with brain metastases should have the capability of safely performing SRS and individual cases should be prospectively reviewed by multidisciplinary teams to provide the best comprehensive care.

Pneumonectomy for lung cancer after preoperative concurrent chemotherapy and high-dose radiation.

BACKGROUND: We studied the clinical characteristics and outcomes of patients undergoing pneumonectomy after preoperative concurrent chemoradiation for non-small cell lung cancer. METHODS: Clinical records of patients with non-small cell lung cancer who underwent pneumonectomy at our institution between 1995 and 2005 after preoperative concurrent chemoradiation were reviewed retrospectively. RESULTS: Twenty-nine patients underwent pneumonectomy after preoperative concurrent chemoradiation. Of the 21 men and 8 women who were treated, 1 had stage IIB (T3N0M0) and the remainder had stage IIIA or IIIB non-small cell lung cancer. Mean patient age at surgery was 53.4 years. There were 15 right pneumonectomies, of which 2 were for pancoast tumors. All patients received concurrent preoperative chemoradiation. Mean total radiation dose was 61.1 Gy. All patients went on to have complete (R0) resection by pneumonectomy. Pathologic complete response was found in 16 patients (55.2%). All patients were discharged alive from the hospital after pneumonectomy. Median hospital length of stay was 5 days (mean 8.6). Ninety-day mortality after surgery was 3.4% (n = 1). Recurrences have been found in 11 patients (38%), including brain metastases (n = 6), bone metastases (n = 4), liver metastases (n = 2), and cervical lymph node metastases (n = 2). One patient had a contralateral new primary lung cancer develop 70 months after undergoing pneumonectomy. Estimated 5-year disease-free survival is 48%. Median survival time has not been reached. CONCLUSIONS: Pneumonectomy can be performed safely after preoperative concurrent chemoradiation, even with high-dose radiation. The frequency of disease recurrence in the brain underscores the need to evaluate the role of prophylactic cranial radiation in non-small cell lung cancer.

The use of gated and 4D CT imaging in planning for stereotactic body radiation therapy.

The localization of treatment targets is of utmost importance for patients receiving stereotactic body radiation therapy (SBRT), where the dose per fraction is large. While both setup or respiration-induced motion components affect the localization of the treatment volume, the purpose of this work is to describe our management of the intrafraction localization uncertainty induced by normal respiration. At our institution, we have implemented gated computed tomography (CT) acquisition with an active breathing control system (ABC), and 4-dimensional (4D) CT using a skin-based marker and retrospective respiration phase-based image sorting. During gated simulation, 3D CT images were acquired corresponding to end-inhalation and end-exhalation. For 4D CT imaging, 3D CT images were acquired corresponding to 8 phases of the respiratory cycle. In addition to gated or 4D CT images, we acquired a conventional free-breathing CT (FB). For both gated and 4D CT images, the target contours were registered to the FB scan in the planning system. These contours were then combined in the FB image set to form the internal target volume (ITV). Dynamic conformal arc treatment plans were generated for the ITV using the FB scan and the gated or 4D scans with an additional 7-mm margin for patient setup uncertainty. We have described our results for a pancreas and a lung tumor case. Plans were normalized so that the PTV received 95% of the prescription dose. The dose distribution for all the critical structures in the pancreas and lung tumor cases resulted in increased sparing when the ITV was defined using gated or 4D CT images than when the FB scan was used. Our results show that patient-specific target definition using gated or 4D CT scans lead to improved normal tissue sparing.

Radiation oncology emergencies.

Radiation therapy is an important and effective treatment modality when used in the management of oncologic emergencies. For any patient who has MSCC, ISCM, SVC syndrome, or life-threatening hemoptysis/obstruction, optimal management hinges on efficient multidisciplinary evaluation and communication to arrive at a treatment plan tailored to the individual patient. Optimal management may include steroids, surgery, chemotherapy, or bronchoscopic intervention. When radiation therapy is used, the total dose and fractionation schedule should be tailored to the disease setting and life expectancy of the patient.

Simultaneous integrated intensity-modulated radiotherapy boost for locally advanced gynecological cancer: radiobiological and dosimetric considerations.

PURPOSE: Whole-pelvis irradiation (WPI) followed by a boost to the tumor site is the standard of practice for the radiotherapeutic management of locally advanced gynecologic cancers. The boost is frequently administered by use of brachytherapy or, occasionally, external-beam radiotherapy (EBRT) when brachytherapy does not provide sufficient coverage because of the size of the tumor or the geometry of the patient. In this work, we propose using an intensity-modulated radiotherapy (IMRT) simultaneous integrated boost (SIB), which is a single-phase process, to replace the conventional two-phase process involving WPI plus a boost. Radiobiological modeling is used to design appropriate regimens for the IMRT SIB. To demonstrate feasibility, a dosimetric study is carried out on an example patient. METHODS AND MATERIALS: The standard linear-quadratic (LQ) model is used to calculate the biologically effective dose (BED) and equivalent uniform dose (EUD). A series of regimens that are biologically equivalent to those conventional two-phase treatments is calculated for the proposed SIB. A commercial inverse planning system (Corvus) was used to generate IMRT SIB plans for a sample patient case that used the newly designed fractionations. The dose-volume histogram (DVH) and EUD of both the target and normal structures for conventional treatments and the SIB are compared. A sparing factor was introduced to characterize the sparing of normal structures. RESULTS: Fractionation regimes that are equivalent to the conventional treatments and are suitable for the IMRT SIB are deduced. For example, a SIB plan with 25 x 3.1 Gy (77.5 Gy) to a tumor is equivalent to a conventional treatment of EBRT of 45 Gy to the whole pelvis in 25 fractions plus a high-dose rate (HDR) brachytherapy boost with 30 Gy in 5 fractions. The normal tissue BED is found to be lower for the SIB plan than for the whole-pelvis plus HDR scheme when a sparing factor for the critical structures is considered. This finding suggests that the IMRT SIB has a better therapeutic ratio. Three IMRT SIB plans with 25 x 1.8 Gy to the pelvic nodes and 25 x 2.4 Gy (60 Gy), 25 x 2.8 Gy (70 Gy), and 25 x 3.2 Gy (80 Gy) to the tumor site were generated for the example patient case. The target coverage ranged from 94% to 95.5%. The sparing of bladder and rectum is significantly improved with the 60 to 70 Gy SIB treatments, as compared with the conventional treatments. The proposed SIB treatment can reduce the treatment time to 5 weeks. CONCLUSIONS: An IMRT simultaneous integrated boost to replace the conventional two-phase treatments (whole pelvic irradiation followed by brachytherapy or EBRT boost) is radiobiologically and dosimetricaly feasible for locally advanced gynecological cancers that may not be amenable to brachytherapy for anatomic or medical reasons. In addition to its shorter treatment time, the proposed IMRT SIB can provide significant sparing to normal structures, which offers potential for dose escalation. Issues such as organ motion and changing anatomy as tumor responds still must be addressed.

Gated CT imaging using a free-breathing respiration signal from flow-volume spirometry.

Respiration-induced tumor motion is known to cause artifacts on free-breathing spiral CT images used in treatment planning. This leads to inaccurate delineation of target volumes on planning CT images. Flow-volume spirometry has been used previously for breath-holds during CT scans and radiation treatments using the active breathing control (ABC) system. We have developed a prototype by extending the flow-volume spirometer device to obtain gated CT scans using a PQ 5000 single-slice CT scanner. To test our prototype, we designed motion phantoms to compare image quality obtained with and without gated CT scan acquisition. Spiral and axial (nongated and gated) CT scans were obtained of phantoms with motion periods of 3-5 s and amplitudes of 0.5-2 cm. Errors observed in the volume estimate of these structures were as much as 30% with moving phantoms during CT simulation. Application of motion-gated CT with active breathing control reduced these errors to within 5%. Motion-gated CT was then implemented in patients and the results are presented for two clinical cases: lung and abdomen. In each case, gated scans were acquired at end-inhalation, end-exhalation in addition to a conventional free-breathing (nongated) scan. The gated CT scans revealed reduced artifacts compared with the conventional free-breathing scan. Differences of up to 20% in the volume of the structures were observed between gated and free-breathing scans. A comparison of the overlap of structures between the gated and free-breathing scans revealed misalignment of the structures. These results demonstrate the ability of flow-volume spirometry to reduce errors in target volumes via gating during CT imaging.