Biomedical subjects

A Eisbruch

Publications and source records attributed to A Eisbruch.

At least 19 recordsLinked to original sources

PubMed1999

Optimization and clinical use of multisegment intensity-modulated radiation therapy for high-dose conformal therapy.

Intensity-modulated radiation therapy (IMRT) may be performed with many different treatment delivery techniques. This article summarizes the clinical use and optimization of multisegment IMRT plans that have been used to treat more than 350 patients with IMRT over the last 4.5 years. More than 475 separate clinical IMRT plans are reviewed, including treatments of brain, head and neck, thorax, breast and chest wall, abdomen, pelvis, prostate, and other sites. Clinical planning, plan optimization, and treatment delivery are summarized, including efforts to minimize the number of additional intensity-modulated segments needed for particular planning protocols. Interactive and automated optimization of segmental and full IMRT approaches are illustrated, and automation of the segmental IMRT planning process is discussed.

Abdominal Neoplasms↗

PubMed1998

Comprehensive irradiation of head and neck cancer using conformal multisegmental fields: assessment of target coverage and noninvolved tissue sparing.

PURPOSE: Conformal treatment using static multisegmental intensity modulation was developed for patients requiring comprehensive irradiation for head and neck cancer. The major aim is sparing major salivary gland function while adequately treating the targets. To assess the adequacy of the conformal plans regarding target coverage and dose homogeneity, they were compared with standard irradiation plans. METHODS AND MATERIALS: Fifteen patients with stage III/IV head and neck cancer requiring comprehensive, bilateral neck irradiation participated in this study. CT-based treatment plans included five to six nonopposed fields, each having two to four in-field segments. Fields and segments were devised using beam's eye views of the planning target volumes (PTVs), noninvolved organs, and isodose surfaces, to achieve homogeneous dose distribution that encompassed the targets and spared major salivary gland tissue. For comparison, standard three-field radiation plans were devised retrospectively for each patient, with the same CT-derived targets used for the clinical (conformal) plans. Saliva flow rates from each major salivary gland were measured before and periodically after treatment. RESULTS: On average, the minimal dose to the primary PTVs in the conformal plans [95.2% of the prescribed dose, standard deviation (SD) 4%] was higher than in the standard plans (91%, SD 7%; p = 0.02), and target volumes receiving <95% or <90% of the prescribed dose were smaller in the conformal plans (p = 0.004 and 0.02, respectively). Similar advantages of the conformal plans compared to standard plans were found in ipsilateral jugular nodes PTV coverage. The reason for underdosing in the standard treatment plans was primarily failure of electron beams to fully encompass targets. No significant differences were found in contralateral jugular or posterior neck nodes coverage. The minimal dose to the retropharyngeal nodes was higher in the standard plans. However, all conformal plans achieved the planning goal of delivering 50 Gy to these nodes. In the conformal plans, the magnitude and volumes of high doses in noninvolved tissue were significantly reduced. The main reasons for hot spots in the standard plans (whose dose calculations included missing tissue compensators) were photon/electron match line inhomogeneities, which were avoided in the conformal plans. The mean doses to all the major salivary glands, notably the contralateral parotid (receiving on average 32% of the prescribed dose, SD 7%) were significantly lower in the conformal plans compared with standard radiation plans. The mean dose to the noninvolved oral cavity tended to be lower in the conformal plans (p = 0.07). One to 3 months after radiation, on average 60% (SD 49%) of the preradiation saliva flow rate was retained in the contralateral parotid glands and 10% (SD 16%) was retained in the submandibular/sublingual glands. CONCLUSIONS: Planning and delivery of comprehensive irradiation for head and neck cancer using static, multisegmental intensity modulation are feasible. Target coverage has not been compromised and dose distributions in noninvolved tissue are favorable compared with standard radiation. Substantial major salivary gland function can be retained.

Carcinoma, Squamous Cell↗

PubMed1998

Customized gynecologic interstitial implants: CT-based planning, dose evaluation, and optimization aided by laparotomy.

PURPOSE: Interstitial perineal implants may be utilized to deliver a high local radiation dose in the treatment of advanced gynecologic malignancies. Lack of knowledge of the precise anatomic relationships between the implant and the target and critical organs may limit efficacy and increase complication risks. Computed tomography (CT)-based planning, dose evaluation, and optimization of customized interstitial implants, aided by laparotomy, have been developed to overcome these limitations. METHODS AND MATERIALS: Twenty patients with locally advanced gynecologic malignancies treated between May 1990 to October 1996 with external irradiation and one or two implants. Interstitial implants were performed when intracavitary brachytherapy was judged to be inadequate or when the response to external radiation and an intracavitary implant was not satisfactory. Customized interstitial implants were planned using preimplantation CT to determine catheter angles and paths that best implanted the target while avoiding pelvic bones and organs. Laparotomy aimed at lysing bowel adhesions, placement of omental carpet, and refining needle placement. Postimplantation CT was used for loading optimization and dose evaluation. RESULTS: Catheter angles 15-25 degrees were found to adequately implant anteriorly laying targets while avoiding pubic bones and bladder. Adhesiolysis of bowel loops from the vaginal apex was required in patients with prior hysterectomy. Small modifications in catheter placements were made during laparotomy in all implants. Postimplantation CTs showed deviations of the catheter positions compared with the planning CTs and were essential in determining target and organ doses and loading optimization. At a median follow-up of 42 months (range: 9-80 months), local control rate is 55% and disease-free survival 40%. Late complications occurred in 2 of 11 of patients without local recurrence. CONCLUSIONS: CT-based planning, loading optimization, and dose evaluation of customized implants improve radiation dose delivery. Laparotomy enhances implant accuracy and safety. Local tumor control rate is still unsatisfactory. It reflects the shortcomings of technical advances alone in poor prognosis tumors like those selected for this series.

Adenocarcinoma↗

PubMed1998

Radiation following chemotherapy for mediastinal Hodgkin's disease: the outcome of various doses for bulky tumors.

Twenty-one patients with bulky mediastinal disease responding to chemotherapy received consolidation with low-dose mediastinal radiation (19.8-25.2 Gy). Their 5-year mediastinal failure rate (10%) was equivalent to that of 10 similar patients who received higher doses of 30-44 Gy (20%). Low-dose radiation may be appropriate for these patients. Prospective studies are required to verify these findings.

Adolescent↗

PubMed1998

Spinal cord dose from standard head and neck irradiation: implications for three-dimensional treatment planning.

BACKGROUND AND PURPOSE: Treatment with traditional standard field arrangements for patients with head and neck cancer rarely causes myelopathy. Often, initial treatment fields are reduced to avoid the spinal cord after 45 Gy has been delivered and the cord dose that is delivered by 'off-cord' fields is not calculated. To determine a conservative limit to set for the cord dose for conformally-planned field arrangements, the total spinal cord dose delivered with standard opposed lateral fields was evaluated. MATERIALS AND METHODS: Two types of treatment plans were evaluated for 10 patients enrolled on a parotid-sparing protocol for bilateral head and neck treatment, i.e. (1) standard opposed lateral fields, including large initial fields treating nodal volumes to 45 Gy, off-cord fields for an additional 25 Gy and electron nodal boost fields for an additional 5 Gy and (2) complex 3-D treatment planned field geometries with conformal dose distributions (actual treatment fields). Treatment fields for the protocol conformal plans were arranged so that the maximum cord dose was not to exceed 50 Gy. Dose-volume histograms for both types of planned treatments were analyzed. The maximum and minimum dose to the 1 cm3 cord volume receiving the highest dose were reported. RESULTS: The maximum dose to the cord from the standard composite plans was on average 52 Gy, with a range of 48.9-55.9 Gy. This consisted of an additional 6.3 Gy (average) from the scatter and block transmission dose from the off-cord lateral fields above the prescribed 45 Gy. For the conformal plans, the maximum dose was on average 49.4 Gy (which is protocol criteria). DISCUSSION AND CONCLUSION: The maximum spinal cord dose of 50 Gy set as a dose constraint for 3-D treatment planning for conformal plans is a comparable dose to that given in standard opposed lateral head and neck treatments and has been determined to be a conservative spinal cord dose limit, which we have applied in our clinic.

Head and Neck Neoplasms↗

PubMed1998

Classification of primary gastric lymphomas according to histologic features.

Histologic features of low-grade gastric lymphomas of mucosa-associated lymphoid tissue (MALT) have been extensively described, and transformation to a large cell (high-grade) lymphoma can occur. We characterize high-grade gastric lymphoma histologically in an attempt to distinguish between MALT-type and non-MALT-type lesions. We studied a series of 60 gastric lymphomas and characterized them clinically, histopathologically, and immunophenotypically. Low-grade gastric lymphomas were classified according to established criteria. High-grade lymphomas were classified in three groups based on the presence or absence of a low-grade component and lymphoepithelial lesions (LELs): 1) high-grade MALT lymphomas appearing in low-grade MALT lymphomas (LG/HG MALT lymphoma); 2) large cell lymphoma with LELs composed of large cells (high-grade LELs) but without a low-grade component (HG MALT lymphoma); and 3) diffuse large cell lymphoma without a low-grade MALT lymphoma component or LELs (DLCL). Twenty-two lymphomas were classified as low-grade MALT lymphomas, 16 as LG/HG MALT lymphomas, 10 as HG MALT lymphomas, and 12 as DLCL. B-cell immunophenotype was confirmed in all 55 cases in which immunophenotyping was performed. Low-grade LELs were seen in all low-grade MALT lymphomas, and CD20(L26) expression confirmed B-cell phenotype in the LELs in 20 of 20 cases. Clinical follow-up was available for 56 patients (range, 1-264 months; mean, 57 months). Actuarial analysis of disease-specific survival and relapse-free survival showed that clinical stage was highly statistically significant (P < 0.0001), whereas histologic type and grade approached statistical significance. Multivariate analysis showed that clinical stage was the only significant factor in relapse-free and disease-specific survival.

Adolescent↗

PubMed1997

What a surgeon needs to know about radiation.

BACKGROUND: A better understanding of the physical and biologic principles of radiation oncology, along with improvements in the technical and clinical aspects of this field, have been gained in recent years. Some of these aspects are presented, with an emphasis on their relevance to the oncologic surgeon. RESULTS: Recent innovations have improved our ability to deliver high radiation doses safely and to increase the therapeutic ratio of radiation. They include the concurrent administration of radiation sensitizers and chemotherapy, altered fractionation schemes, and the conformal delivery of radiation using sophisticated imaging and planning tools. CONCLUSIONS: The increasing efficacy of radiation, resulting from innovations described in this review and others, enhances the role of radiotherapy in the struggle against cancer.

Antineoplastic Agents↗

PubMed1997

Design and analysis of an immobilization and repositioning system for treatment of neck malignancies.

Recent applications of three-dimensional treatment planning using non-coplanar treatment angles have demonstrated the potential for improved target dose homogeneity as well as normal tissue sparing for tissues in the neck, notably the parotid gland. Implementation of these highly targeted treatments requires a reliable method for accurate daily reproduction of the treatment position, as patient setup error could lead to significant decreases in target dose and normal tissue sparing. Additionally, the constrained geometry of this anatomic site requires the freedom to deliver treatments from any arbitrary angle in order to maximize the expected benefit. In order to permit accurate setup while maintaining access from most angles, a hybrid immobilization system has been developed, consisting of a custom thermoplastic mask with attachment to a foam cradle shaped to the back of the patient. To evaluate the accuracy of this system, setup errors were measured in 20 patients treated while immobilized with the positioning aide. Two orthogonal film sets consisting of anterior and lateral projections, one set taken at the beginning of treatment and a second 4-5 weeks into therapy, were compared to baseline simulator films or digitally reconstructed radiographs. The average setup deviation in any direction ranged from 0.8 to 1.4 mm and the largest single setup error observed was 4.5 mm. For the film sets taken late in treatment only 3 of the 20 patients required setup adjustment followed by repeat filming to obtain an acceptable film pair. This system has been implemented for routine clinical use since March 1995.

Equipment Design↗

PubMed1997

Planned early neck dissection before radiation for persistent neck nodes after induction chemotherapy.

Optimal management of advanced neck metastases as part of an organ preservation treatment approach for head and neck squamous carcinoma (HNSC) is unclear. Since 1989, our management paradigm for patients on organ preservation was modified to incorporate planned early neck dissection before radiation therapy for patients who did not achieve a complete response (CR) of neck nodes after induction chemotherapy (IC). The purpose of this study was to determine if planned early neck dissection is a safe and effective approach in the management of advanced nodal disease as part of organ preservation. Fifty-eight consecutive patients with advanced HNSC who were entered in organ preservation trials using induction chemotherapy and radiation with surgical salvage were studied. Median follow-up was 26 months. Of the 58 patients, 71% were stage IV. Patients were grouped by nodal response to chemotherapy and N class, and were analyzed with respect to patterns of recurrence, complications, and survival. Overall, the rate of CR of neck nodes was 49%. Fifty-one percent had less than a complete response of neck nodes after IC and required planned early neck dissection. There were no significant differences in patterns of recurrence, complications, interval time to start of radiation, recurrence, or survival rates between the CR and less than CR groups. These data suggest that planned early neck dissection for patients with less than CR in the neck after IC is not detrimental with respect to neck relapse or overall survival. We believe that planned early neck dissection can be safely incorporated into future organ preservation treatment protocols for patients with advanced head and neck carcinoma.

Adult↗

PubMed1997

Parotid sparing study in head and neck cancer patients receiving bilateral radiation therapy: one-year results.

Many patients with head and neck cancers receive radiation therapy as part of their treatment which frequently causes considerable morbidity, including various degrees of permanent salivary gland dysfunction. Three-dimensional treatment planning [3-DTP] and conformational dose delivery constitute a new therapeutic modality that conforms the high-dose radiation volume to the shape of the tumor volume while minimizing the dose to tissue that is not at risk of containing cancer. The treatment volumes for head and neck tumors as well as parotid glands can be well-defined on cross-sectional CT imaging techniques. The purpose of this investigation is to determine if 3-DTP and conformational dose-delivery could minimize radiation dose and salivary gland dysfunction to contralateral parotid glands in patients with head and neck cancers. Eleven patients with head and neck cancers who required bilateral radiation therapy were treated with 3-DTP. Unstimulated and stimulated bilateral parotid saliva was collected prior to radiotherapy, weekly during treatment, and 1, 3, 6, and 12 months after the completion of radiotherapy. Treated parotid glands received an average dose of 5745 cGy, while spared glands received only 1986 cGy (p < 0.0001). Unstimulated and stimulated parotid flow rates decreased dramatically in treated glands after the initiation of radiotherapy, remained at extremely low rates without any improvements, and were significantly lower at 1 year after radiotherapy compared with baseline. Conversely, parotid flow rates in spared glands underwent mild changes during radiotherapy and were approximately 50% of baseline values. The results of this study suggest that with the use of 3-DTP, contralateral parotid gland function can be partially preserved for at least 1 year in patients with head and neck cancers requiring bilateral radiation.

Aged↗

PubMed1997

Gemcitabine-mediated radiosensitization.

Gemcitabine is a potent radiosensitizer of human tumor cells. This review summarizes our preclinical and early clinical studies designed to elucidate the mechanism of action of gemcitabine and phase I trials conducted to determine the optimal dose and schedule. Gemcitabine was found to radiosensitize a wide variety of human tumor cells in culture, particularly cells derived from cancers of the pancreas, breast, and head and neck. Radiosensitization occurs under conditions in which cells demonstrate concurrent redistribution into S phase and deoxyadenosine triphosphate pool depletion. These conditions can be produced by either a long (24-hour) exposure to a low concentration of gemcitabine (10 nmol/L) or by a brief (2-hour) treatment with higher but clinically relevant concentrations (100 nmol/L to 3 micromol/L). Under the latter conditions, sensitization can be detected 4 hours after treatment and last for up to 2 days. These preclinical data were useful in the design of a gemcitabine dose escalation trial in combination with standard radiation for patients with unresectable head and neck cancer. Although this trial is not yet complete, the starting dose of gemcitabine, which is far below the maximum tolerated dose for the drug when used alone, significantly potentiates the toxicity of radiation treatment. We conclude that gemcitabine is a promising radiation sensitizer that needs to be developed cautiously if excessive normal tissue toxicity is to be avoided.

Carcinoma, Squamous Cell↗

PubMed1996

Parotid gland sparing in patients undergoing bilateral head and neck irradiation: techniques and early results.

PURPOSE: To minimize xerostomia in patients receiving bilateral head and neck irradiation (RT) by using conformal RT planning to spare a significant volume of one parotid gland from radiation. METHODS AND MATERIALS: The study involved 15 patients with head and neck tumors in whom bilateral neck radiation was indicated. The major salivary glands and the targets (tumor, surgical bed, metastases to lymph nodes, and the locations of lymph nodes at risk for metastases) were outlined on axial computed tomography images. Beam's-eye view (BEV) displays were used to construct conformal beams that delivered the prescribed doses to the targets while sparing from direct radiation most of one parotid gland. The gland that was planned to be spared resided in the neck side that was judged in each patient to be at a lesser risk of metastatic disease. Major salivary gland flow rates and the responses to a subjective xerostomia questionnaire were assessed before, during, and after radiation. RESULTS: Radiation planning for patients with central oropharyngeal tumors required the generation of multiple axial nonopposed beams. The resulting isodoses encompassed the targets, including the retropharyngeal nodes and the jugular nodes up to the base of skull bilaterally, while limiting the dose to the oral cavity, spinal cord, and one parotid gland. For patients with lateralized tumors, the ipsilateral neck side was treated up to the base of the skull; in the contralateral neck side, the treatment included the subdigastric nodes but excluded the jugular nodes at the base of the skull and most of the parotid gland. This was accomplished by a moderate gantry angle that was chosen using the BEV displays. Three months following the completion of radiation, the spared parotid glands retained on average 50% of their unstimulated and stimulated flows. In contrast, no saliva flow was measured from the unspared glands in any of the patients. Subjective xerostomia was absent, mild, or not different from that reported before radiation in 10 of 15 patients (67%). CONCLUSION: Partial parotid gland sparing is feasible by using three-dimensional planning in patients undergoing bilateral head and neck radiation. Approximately 50% of the saliva flow from the spared glands may be retained, and most patients thus treated have no or mild xerostomia in the early period after the completion of radiation. Whether tumor control and late complications are comparable to standard radiation will be assessed as more experience is gained.

Aged↗

PubMed1996

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.

Adult↗

PubMed1996

Treatment planning for parotid sparing in the patient requiring bilateral neck irradiation.

The use of three dimensional (3-D) planning techniques for treatment of head and neck cancers has primarily been used in cases which require only unilateral neck irradiation. However, tumors that require bilateral neck irradiation are commonly managed with parallel opposed treatment portals. A common morbidity associated with this standard form of treatment is xerostomia. In an effort to reduce the incidence of this debilitating side effect, a protocol has been developed which attempts to balance effective tumor control with preservation of salivary flow. Key to this protocol is the use of 3-D treatment planning. The close proximity of the targeted tissues to critical structures and the related dose requirements and/or restrictions of these tissues often require the treatment planner to utilize "non-standard" approaches to achieve the unique dose distributions necessary to meet protocol eligibility. This may include treatment planning options such as non-coplanar, non-axial beams; and modulation of beam intensity.

Head and Neck Neoplasms↗

PubMed1996

Ipsilateral parotid sparing study in head and neck cancer patients who receive radiation therapy: results after 1 year.

OBJECTIVE: To determine if three-dimensional treatment planning and conformational dose delivery could minimize radiation dose and salivary gland dysfunction to contralateral parotid glands in patients with unilateral head and neck cancers. STUDY DESIGN: Fifteen patients with unilateral head and neck cancers were treated with three-dimensional treatment planning. Unstimulated and stimulated bilateral parotid saliva was collected before radiotherapy, weekly during treatment, and 1, 3, 6, and 12 months after the completion of radiotherapy. RESULTS: Treated parotid glands received an average dose of 4949 cGy, whereas spared glands received only 355 cGy. Unstimulated and stimulated parotid flow rates decreased dramatically in treated glands after the initiation of radiotherapy and were significantly lower at 1 year after radiotherapy compared with baseline. Conversely, parotid flow rates in spared glands underwent mild changes during radiotherapy and were similar at 1 year after radiotherapy compared with baseline. CONCLUSION: Parotid gland function can be preserved for at least 1 year in patients with unilateral head and neck cancers with three-dimensional treatment planning.

Adult↗

PubMed1996

Chemotherapy followed by accelerated fractionated radiation for larynx preservation in patients with advanced laryngeal cancer.

PURPOSE: Larynx preservation in advanced, resectable laryngeal cancer may be achieved using induction chemotherapy (CT) followed in responding patients by definitive radiation (RT). To address potential accelerated repopulation of clonogenic tumor cells during the prolonged total treatment time, we studied the feasibility of accelerated fractionated RT after CT. METHODS: Patients with advanced laryngeal cancer received two cycles of cisplatin 100 mg/m2 and fluorouracil (5-Fu) 1,000 mg/m2/d for 5 days. Responding patients received a third cycle after which those who had complete response or tumor down-staging to T1 proceeded with accelerated RT: 70.4 Gy delivered over 5.5 weeks. Patients who achieved a lesser response to CT underwent total laryngectomy and postoperative RT. RESULTS: Thirty-three patients were accrued. Three died during the course of CT and two declined definitive treatment after CT. Twenty-one patients had a major response to CT, 20 of whom received accelerated RT. Median weight loss during RT was 11%. Late severe morbidity was observed in five patients (25%). All four patients who underwent salvage laryngectomy after accelerated RT experienced major postoperative complications. The locoregional failure rate was 25%. The larynx was preserved in 48% of the total study population and in 80% of the patients irradiated according to the study protocol. CONCLUSION: Accelerated RT after CT as delivered in this study may increase both acute and long-term morbidity rates compared with studies using standard RT after CT. It did not seem to improve local/regional tumor control or survival despite stringent patient selection criteria.

Adult↗

PubMed1994

Adjuvant irradiation after prostatectomy for carcinoma of the prostate with positive surgical margins.

BACKGROUND: Patients with adenocarcinoma of the prostate treated with prostatectomy who have tumor at the margins of the surgical specimen or tumor involvement of the seminal vesicles have a high risk of local recurrence and metastatic disease. It is unclear whether postoperative irradiation improves their outcome. METHODS: This is a retrospective analysis of patients treated with prostatectomy for adenocarcinoma of the prostate who had surgical margins or seminal vesicles involved by tumor. Thirty-four patients received adjuvant postoperative irradiation (Group 1), and 43 patients did not receive irradiation (Group 2). RESULTS: The tumor control rates in the prostatic bed for patients who had radical prostatectomy were 100% and 84% in Groups 1 and 2, respectively (P = 0.017). Actuarial 10-year disease-free survival from the date of prostatectomy was 46% and 55% for Groups 1 and 2, respectively. CONCLUSIONS: Adjuvant irradiation after prostatectomy in patients with positive surgical margins or seminal vesical invasion increases prostatic bed local tumor control but does not affect survival. Postoperative irradiation is associated with acceptable morbidity.

Adenocarcinoma↗

PubMed1993

Estimation of tissue volume irradiated by intracavitary implants.

PURPOSE: The volume of space enclosed by a specified isodose surface arising from an intracavitary implant may correlate with clinical outcome. Several investigators have proposed using the product of the three maximum orthogonal dimensions of the isodose surface as a measure of this volume. We have examined the accuracy of this proposal and compared it to a simpler model for estimating volume which requires only knowledge of the mgRaEq-hrs (total reference air kerma) and the dose level. METHODS AND MATERIALS: Orthogonal films from 204 intracavitary implants of 128 patients with carcinoma of the cervix were used to reconstruct the 137Cs-source coordinates. The source location, strength and duration data were used to calculate dose-volume histograms, yielding the volume enclosed by each dose level as well as its orthogonal dimensions: thickness, width, and height. Using bony landmarks to align films for different insertions in the same patient, similar calculations were repeated for composite implant source coordinates. RESULTS: Curve-fitting techniques revealed that the volume encompassed by each isodose level could be predicted by a modified power-law function of the mgRaEq-hr/dose ratio: predicted volume = [104.8 - 8.103.(M/D) + 0.437.(M/D)2].(M/D)1.635 where M/D = mgRaEq-hr/cGy. The volume predicted by this simple model is accurate within +/- 10% in 95% of the implants when mgRaEq-hr/cGy = 0.8. Accuracy increases with increasing mgRaEq-hr/cGy. In contrast, the ratio, product of orthogonal dimensions/actual volume, varies widely from implant-to-implant, as well as differing systematically from one implant type to another. Investigation of the individual orthogonal dimensions demonstrated that width and height, but not thickness, were moderately well correlated with corresponding maximum implant dimensions. However, in all cases the dimensions were more sensitive to changes in mgRaEq-hr/cGy than to changes in implant geometry. CONCLUSIONS: The product of the orthogonal dimensions is an unsatisfactory estimator of the actual irradiated volume encompassed by an isodose surface. Isodose surface volumes can be accurately estimated knowing only mgRaEq-hr. Prescribing intracavitary brachytherapy by mgRaEq-hr, or its derivative, total reference air kerma, is equivalent to requiring that an isodose surface encompass a specified volume which does not depend on the implant geometry. Constraining the mgRaEq-hr delivered therefore serves to limit the volume of tissue irradiated to high doses.

Brachytherapy↗