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H M Sandler

Publications and source records attributed to H M Sandler.

At least 37 records · Page 2Linked 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

Patterns of failure following treatment for medulloblastoma: is it necessary to treat the entire posterior fossa?

PURPOSE: Craniospinal radiation (CSRT) followed by a boost to the entire posterior fossa (PF) is standard postoperative therapy for patients with medulloblastoma. A large proportion of recurrences after treatment are local, with approximately 50-70% of recurrences occurring in the PF. It is unclear, however, whether these failures are occurring in the original tumor bed or outside the tumor bed, but still within the PF. With improved diagnostic imaging, better definition of tumor volumes, and the use of three-dimensional conformal therapy (3D CRT), we may be able to restrict the boost volume to the tumor bed plus a margin without compromising local control. This retrospective study analyzes the patterns of failure within the PF in a series of patients treated with radiation therapy (RT). METHODS: From July 1986 through February 1996, 114 patients >18 months and <18 years with medulloblastoma were treated at the University of Michigan and Children's Hospital of Philadelphia, with RT following surgical resection. Of 114, 27 (24%) were found to have a recurrence and form the basis for this study. RT consisted of CSRT followed by a boost to the entire posterior fossa. Some patients received adjuvant chemotherapy. Patient's preoperative magnetic resonance imaging (MRI) and/or computerized tomography (CT) studies were used to compare the original tumor volume with the specific region of local relapse. Failure was defined as MRI or CT evidence of recurrence or positive cerebrospinal fluid cytology. Relapse was scored as local, if it was within the original tumor bed, and regional if it was outside of the tumor bed but still within the PF. RESULTS: The median age of the 27 patients who relapsed was 8.6 years. Three patients were <3 years old. Of 27, 21 had disease localized to the PF. Of 26, 22 patients received chemotherapy during their treatment regimen; 1 patient did not have information on systemic treatment. The median dose of RT to the craniospinal axis was 32.5 Gy and to the PF was 55.2 Gy. The median time to recurrence was 19.5 months. Local failure within the tumor bed as any component of first failure occurred in 52% (14 of 27) of all failures, but as the solitary site of first failure in only 2 of 27 failures. Of 14 patients who failed in the tumor bed, 11 also failed in the spine, 8 of 14 also failed within the PF but outside the tumor bed, and 7 of 14 failed in all three locations. Local failure within the PF but outside the tumor bed as any component of first failure occurred in 41% (11 of 27) of all failures, but as the solitary site of first failure in only 1 of 27 failures. Of 11 patients who failed in the PF but outside the tumor bed, 9 also failed in the spine, 8 also failed within the tumor bed, and 7 failed in the all three locations. Of the failures outside the tumor bed but still within the PF, 7 of 11 failed in the leptomeninges, 1 in the brainstem parenchyma, and 3 in the PF parenchyma. Of 7 who failed in the PF leptomeninges, 6 also failed within the spine. Failure within the spine as any component of first failure occurred in 70% (19 of 27) of all failures and as the only site of first failure in 5 of 27 patients. Of 19 patients who failed in the spine, 11 also failed in the tumor bed, 9 also failed within the PF but outside the tumor bed, and 9 failed in the all three locations. CONCLUSIONS: Leptomeningeal failure is a common component of failure and occurs in the leptomeninges of the PF, as well as the spine. Isolated tumor bed failure is a rarely observed event and occurred in only 2 of 27 failures described here. Similarly, parenchymal (nonleptomeningeal) failures in the PF but outside of the tumor bed were rare: 4 patients recurred in this manner, only 1 of whom was an isolated event without other sites of recurrence. Our data suggest that, when the entire PF is treated, very few failures develop in isolation in the PF outside the tumor bed. Further studies will be necessary to determine if RT to the tu

Adolescent↗
PubMed1998

A brain tumor dose escalation protocol based on effective dose equivalence to prior experience.

PURPOSE: The current study describes the design of a dose escalation protocol for conformal irradiation of primary brain tumors that preserves the safe experience of a previous, sequential dose escalation scheme while enabling the delivery of substantially higher effective doses to a central target volume. METHODS AND MATERIALS: Normalized isoeffective composite dose distributions were formed for 20 patients treated on the original protocol (which specified three progressively smaller planning target volumes [PTVs]) using the linear quadratic model (here corrected to equivalent 2 Gy fractions using alpha/beta=10 Gy). These distributions were investigated and a new protocol was designed to preserve a similar level of efficacy and lack of toxicity for the outer volumes, but allowing a higher dose to the inner PTV. Treatment plans were then investigated to determine if the objectives of the new protocol were achievable. In particular, plans that simultaneously achieved all biological treatment planning objectives (all fields treated each day) were investigated. Finally, the success of the protocol design was demonstrated by analysis of the effective dose distributions of 10 patients treated using the new protocol. RESULTS: The composite normalized isoeffective minimum doses to the outer PTVs (PTV3 and PTV2) in the original protocol were close to 60 Gy and 75 Gy, respectively, and these values are specified as the minimum doses to those volumes for the new protocol. Homogeneity requirements to maintain equivalence for the outer target volume domains are: not more than 25% of [PTV3 exclusive of PTV2] >75 Gy; and not more than 50% of [PTV2 exclusive of PTV1] >85 Gy. Treatment plans using multiple noncoplanar arrangements of beams and static intensity modulation treat all volumes at each session. DVHs of the normalized isoeffective dose distributions reveal the equivalence of the new protocol plans to the sequential plans in the previous protocol as well as the ability to achieve a higher dose of 90 Gy to the isocenter of PTV1 (+/-5% homogeneity required). CONCLUSION: The ability to incorporate past experience through use of the linear quadratic model in the design of a new dose escalation protocol is demonstrated.

Brain Neoplasms↗
PubMed1998

The use of 3D conformal radiotherapy (3D CRT) to spare the cochlea in patients with medulloblastoma.

PURPOSE: Radiation therapy in combination with cis-platinum chemotherapy is associated with ototoxicity due to destruction of cochlear hair cells. This is a significant problem, especially in pediatric patients, because it may lead to difficulties with communication, speech, language, and development of learning skills. The use of 3D conformal radiotherapy (3D CRT) may be useful in sparing auditory structures. This paper discusses a technique using 3D CRT to spare the cochlea in patients with medulloblastoma. METHODS AND MATERIALS: Five pediatric patients with medulloblastoma were planned using 3D CRT. All had MRI and CT obtained specifically for treatment planning. Multiple structures were contoured, including the cochlea and posterior fossa, and conformal beams designed in beam's eye view and dose distribution analysis were edited to provide 3D dose coverage to the target while sparing the inner ear. Patients received 36 Gy to the craniospinal axis followed by an 18-20 Gy boost to the posterior fossa. RESULTS: A 3D CRT cochlear sparing technique was designed, using an axial pair of posterior oblique fields to treat the posterior fossa while sparing the cochlea for all patients in this analysis. Dose-volume information, obtained from 3D calculations, demonstrates that the average dose received by the cochlea was 65% of the prescribed dose using the cochlear sparing plan, as compared to 101% using standard opposed-lateral beams. Both plans delivered > or = 100% of the prescribed dose to the posterior fossa. CONCLUSION: 3D CRT allows for cochlear sparing in the treatment of medulloblastoma. Further follow-up is necessary to determine the long-term benefit in these patients.

Cerebellar Neoplasms↗
PubMed1998

Controversies in the management of stage I seminoma.

Current controversies in the treatment of stage I seminoma center on the relative roles of surveillance, adjuvant radiotherapy (RT), and adjuvant single-agent chemotherapy. Surveillance has been studied in over 800 patients, 17.1% of whom have relapsed. There is no evidence that surveillance compromises survival in properly selected, compliant patients. The economic benefit of treating only those patients who relapse is offset by the cost of screening diagnostic studies and salvage therapy, and by issues of patient anxiety and compliance. Other methods of reducing the toxicity of RT include reductions in RT dose and volume. A randomized trial has shown that omission of the pelvic field produces relapse-free survival equivalent to that achieved with pelvic plus para-aortic RT. A similar study is currently evaluating a reduction in RT dose from 30 to 20 Gy. Early results from nonrandomized studies of one or two cycles of single-agent chemotherapy demonstrate efficacy comparable to RT in the adjuvant treatment of stage I seminoma. A randomized trial is underway to determine the equivalence of adjuvant carboplatin (Paraplatin) and RT. Long-term follow-up from these studies will provide information not only on the relative efficacy of these alternative strategies but also on the late effects of therapy, including infertility and second malignancy.

Chemotherapy, Adjuvant↗
PubMed1997

Rate of PSA rise predicts metastatic versus local recurrence after definitive radiotherapy.

OBJECTIVE: A rising prostate specific antigen (PSA) following treatment for adenocarcinoma of the prostate indicates eventual clinical failure, but the rate of rise can be quite different from patient to patient, as can the pattern of clinical failure. We sought to determine whether the rate of PSA rise could differentiate future local versus metastatic failure. METHODS AND MATERIALS: Two thousand six hundred sixty-seven PSA values from 400 patients treated with radiotherapy for localized adenocarcinoma of the prostate were analyzed with respect to PSA patterns and clinical outcome. Patients had received no hormonal therapy or prostate surgery and had > 4 PSA values post-treatment. PSA rate of rise, determined by the slope of the natural log, was classified as gradual [< 0.69 log(ng/ml)/year, or doubling time (DT) > 1 year], moderate [0.69-1.4 log(ng/ml)/year, or DT 6 months-1 year], or rapid [> 1.4 log(ng/ml)/year, or DT < 6 months]. RESULTS: Sixty-one percent of patients had non-rising PSA following treatment; 25% of patients with rising PSA developed clinical failure, and 93% of patients with clinical failure had rising PSA. The rate of rise discerned different clinical failure patterns. Local failure occurred in 23% of patients with moderate rate of rise versus 7% with gradual rise (p = 0.0001). Metastatic disease developed in 46% of those with rapid rise versus 8% with moderate rise (p < 0.0001). By multivariate analysis, in addition to rate of rise, PSA nadir and rate of decline predicted local failure; those with post-treatment nadir of 1-4 ng/ml were five times more likely to experience local failure than nadir < 1 ng/ml (p = 0.0002). Rapid rate of rise was the most significant independent predictor of metastatic failure. CONCLUSIONS: The rate of PSA rise following definitive radiotherapy can predict clinical failure patterns, with a rapidly rising PSA indicating metastatic recurrence and moderately rising PSA local recurrence. This information could potentially direct therapy; if the rise predicts metastatic failure hormonal therapy could be considered, while aggressive salvage therapy may benefit subclinical local recurrence identified by a moderate rate of PSA rise.

Adenocarcinoma↗
PubMed1997

Prostate cancer susceptibility locus on chromosome 1q: a confirmatory study.

BACKGROUND: Recent recognition that a predisposition to prostate cancer can be inherited has led to a search for specific genes associated with the disease. Through a study of families with three or more affected first-degree relatives, a region on the long arm of chromosome 1 (i.e., 1q24-25) has been tentatively identified as containing a gene, HPC1, involved in the development of hereditary prostate cancer. Confirmation of this finding is needed, however, before attempts are made to isolate and characterize the putative HPC1 gene. PURPOSE: To confirm that chromosome 1q24-25 contains a gene relevant to hereditary prostate cancer, we analyzed an independent set of families, each with two or more affected individuals. METHODS: Fifty-nine unrelated families were selected for analysis on the sole criterion that more than one living family member was affected by prostate cancer. DNA samples were subsequently isolated from 130 individuals with the disease. These samples were genotyped at six polymorphic marker sequences (D1S215, D1S2883, D1S466, D1S158, D1S518, and D1S2757) covering the chromosomal region proposed to contain HPC1. The resulting data were analyzed by nonparametric multipoint linkage (NPL) methods, yielding NPL Z scores and corresponding one-sided P values. RESULTS: When the entire set of 59 families was considered, the occurrence of prostate cancer (and, presumably, the HPC1 gene) was most tightly linked to marker D1S466 (NPL Z score = 1.58; P = .0574). Analysis of the 20 families (51 affected individuals) fulfilling one or more of the proposed clinical criteria for hereditary prostate cancer (i.e., three or more affected individuals within one nuclear family; affected individuals in three successive generations [maternal or paternal lineage]; and/or clustering of two or more individuals affected before the age of 55 years) revealed more convincing evidence of disease linkage to chromosome 1q24-25 (maximum NPL Z score [at marker D1S466] = 1.72; P = .0451). The 39 families (79 affected individuals) that did not meet the clinical criteria for hereditary prostate cancer exhibited no significant evidence of disease linkage to DNA sequences at chromosome 1q24-25 (maximum NPL Z score [at marker D1S466] = 0.809; P = .208). The six African-American families in our study contributed disproportionately to the observation of linkage, with a maximum NPL Z score at marker D1S158 of 1.39 (P = .0848) for these families. CONCLUSIONS AND IMPLICATIONS: Our data confirm that chromosome 1q24-25 is likely to contain a prostate cancer susceptibility gene. Future efforts at positional cloning of the HPC1 gene should focus on families who meet the proposed clinical criteria for hereditary prostate cancer.

Adult↗
PubMed1997

Dose-volume complication analysis for visual pathway structures of patients with advanced paranasal sinus tumors.

PURPOSE: The purpose of the present work was to relate dose and volume information to complication data for visual pathway structures in patients with advanced paranasal sinus tumors. METHODS AND MATERIALS: Three-dimensional (3D) dose distributions for chiasm, optic nerve, and retina were calculated and analyzed for 20 patients with advanced paranasal sinus malignant tumors. 3D treatment planning with beam's eye view capability was used to design beam and block arrangements, striving to spare the contralateral orbit (to lessen the chance of unilateral blindness) and frequently the ipsilateral orbit (to help prevent bilateral blindness). Point doses, dose-volume histogram analysis, and normal tissue complication probability (NTCP) calculations were performed. Published tolerance doses that indicate significant risk of complications were used as guidelines for analysis of the 3D dose distributions. RESULTS: Point doses, percent volume exceeding a specified published tolerance dose, and NTCP calculations are given in detail for patients with complications versus patients without complications. Two optic nerves receiving maximum doses below the published tolerance dose sustained damage (mild vision loss). Three patients (of 13) without optic nerve sparing and/or chiasm sparing had moderate or severe vision loss. Complication data, including individual patient analysis to estimate overall risk for loss of vision, are given. CONCLUSION: 3D treatment planning techniques were used successfully to provide bilateral sparing of the globe for most patients. It was more difficult to spare the optic nerves, especially on the ipsilateral side, when prescription dose exceeded the normal tissue tolerance doses. NTCP calculations may be useful in assessing complication risk better than point dose tolerance criteria for the chiasm, optic nerve, and retina. It is important to assess the overall risk of blindness for the patient in addition to the risk for individual visual pathway structures.

Blindness↗
PubMed1997

Results of 3D conformal radiotherapy in the treatment of localized prostate cancer.

PURPOSE: 3D conformal radiotherapy (3D CRT) has been shown to decrease acute morbidity in the treatment of prostate cancer. Therapeutic outcome and late morbidity data have been accumulating. To evaluate the results of 3D CRT for the treatment of prostate cancer, we analyzed the outcome of a large series of patients treated with conformal techniques. MATERIAL AND METHODS: From January 1987 through June 1994, 707 patients with localized prostate cancer were treated with 3D CRT. Patients with pathologically-confirmed pelvic lymph node metastasis, treated with pre-irradiation (preRT) androgen ablation, or treated post-prostatectomy were excluded. All had CT obtained specifically for treatment planning, multiple structures contoured on the axial images, and beam's-eye view conformal beams edited to provide 3D dose coverage. Median follow-up is 36 mos; 70 patients have been followed longer than 5.5 years. Six hundred three had T1-T2 tumors. PreRT prostate specific antigen (PSA) was available for 649 patients: median preRT PSA was 12.9 ng/ml, 209 patients had preRT PSA > 20 ng/ml. The median dose of radiation was 69 Gy; 102 patients received > or = 69 Gy. Biochemical failure was defined as: 1) two consecutive PSA rises over 2.0 ng/ml if nadir PSA < or = 2.0 ng/ml, 2) two consecutive PSA rises over nadir if nadir PSA > 2.0 ng/ml, or 3) initiation of hormonal therapy after RT. Complications were graded using the RTOG system. RESULTS: PreRT PSA and Gleason score emerged as independent indicators of biochemical control (bNED). Patients with preRT PSA > 10 had a significantly worse bNED at 5 years than patients with preRT PSA < or = 10. Five-year bNED was determined according to preRT PSA: PSA < or = 4, 88%; PSA > 4 < or = 10, 72%; PSA > 10 < or = 20, 43%; and PSA > 20, 30%. Patients with Gleason score > or = 7 also had a significantly worse bNED than patients with Gleason score < 7. Patients were divided into two prognostic groups: a favorable group with PSA < or = 10, Gleason score < 7, and T1-T2 tumors, and an unfavorable group with PSA > 10, Gleason score > or = 7 or T3-T4 tumors and studied for the effect of dose on bNED status. The bNED at 5 years was 75% for the favorable group and 37% for the unfavorable group. In addition, a group that might be considered a surgical subset was reviewed: patients with PSA < or = 10, Gleason score < or = 7, and T1-T2 tumors who were < 70 years old. This subset had an 84% 5-year bNED rate and 98% 5-year overall survival. Complications with the techniques used here are very low: 3% risk at 7 years of Grade 3-4 complications and 1% risk at 7 years of Grade 3 bladder complications (no Grade 4). CONCLUSION: 3D CRT allows for treatment of prostate cancers with a very low risk of complications. Patients with relatively early disease as defined by preRT PSA, Gleason score < 7, and T1-2 tumors and patients who are candidates for radical prostatectomy have excellent 5-year bNED rates. Patients with adverse prognostic factors have a high risk of biochemical recurrence and are candidates for innovative therapy.

Adult↗
PubMed1997

A single plan approach for differentially dosing sequential target volumes.

An in-house protocol for treatment of malignant astrocytomas requires development of a single treatment plan constructed to deliver different doses to three sequential target volumes. This single plan approach fundamentally differs from a previous protocol in which these sequential volumes were approached with three consecutive treatment plans, each tailored to a separate target, with the final target receiving a cumulative dose of 80 Gy. The intent of the revised protocol is to deliver doses to the two larger targets that are biologically equivalent (using the linear quadratic model) to the cumulative doses received by these targets in the earlier protocol, while escalating the final target dose to 90 Gy. This requires the treatment planner to manipulate the conformation of three different isodose levels simultaneously to produce a treatment plan fulfilling all protocol specifications. This paper will focus on the evolution of design for the current technique used to clinically implement this protocol.

Astrocytoma↗
PubMed1997

Results of re-irradiation of primary intracranial neoplasms with three-dimensional conformal therapy.

We evaluated the potential of three-dimensional conformal therapy for re-irradiation of selected intracranial neoplasms and reviewed the retreatment of 20 patients at the University of Michigan between May 1988 and August 1991. All patients had previously undergone a full course of external beam radiotherapy (RT) to a median dose of 5,940 cGy (range 5,100-6,500 cGy), including five whole brain treatments. All recurrences were unsuitable for brachytherapy or radiosurgery. Various histologies were retreated, including 14 high-grade gliomas. Median time to re-irradiation was 38 months (range 9 months to 19 years, 6 months). RT was delivered with complex plans designed using fully integrated computed tomography/magnetic resonance imaging (CT/ MRI) tumor volume information, and regions of previous parenchymal treatment were avoided if possible. Composite (initial+retreatment) dose-volume histograms (DVH) of dose to nontarget brain allowed comparison of alternative plans to select beam orientations which minimized normal brain irradiation. Mean target dose of re-irradiation was 3,600 cGy (range 3,060-5,940 cGy). Total cumulative dose ranged from 8,060 to 11,940 cGy. Median survival was 9 months, and 1-year actuarial survival was 26%. After retreatment, 8 of 12 patients (67%) had steroid dose decrement and neurologic improvement at 4-48 months (median duration 14 months). Radiographic regression or stabilization of disease was noted in 11 of 16 patients (68%). Re-irradiation with highly conformal three-dimensional planning provides frequent clinical improvement with acceptable morbidity and should be considered in selected patients with recurrent intracranial neoplasms.

Actuarial Analysis↗
PubMed1997

Pituitary irradiation is ineffective in normalizing plasma insulin-like growth factor I in patients with acromegaly.

Pituitary irradiation suppresses GH hypersecretion in patients with acromegaly. Within 10 yr after radiotherapy, up to 80% of patients achieve plasma GH levels below 5 micrograms/L. Whether this is sufficient to normalize plasma insulin-like growth factor I (IGF-I) levels, is unknown. We examined the effect of radiotherapy on plasma IGF-I concentrations in patients with acromegaly. We reviewed hospital charts of 140 patients with acromegaly seen in our institution between 1975 and 1996. Data on plasma GH and IGF-I were extracted and tabulated longitudinally together with the information about the concomitant medical therapy. We included data from the patients who received radiotherapy as a part of their treatment and whose IGF-I was monitored for more than 1 yr afterward. To avoid the potential bias, the data for patients who were referred to us for medical therapy, having failed radiation elsewhere, were excluded. A total of 38 datasets were submitted for the final analysis. The average follow-up was 6.8 +/- 0.8 yr (range, 1-19). Only 2 patients achieved age- and sex-adjusted normal IGF-I levels while off medical therapy. Noncured patients had a mean plasma GH level of 4.6 +/- 1.1 micrograms/L but still elevated plasma IGF-I levels (219 +/- 26% of the upper normal limit) at the last follow-up visit. A random GH concentration below 1.5 micrograms/L was associated with a pathologically high plasma IGF-I concentration in 43% of instances. Radiotherapy appears to be ineffective in normalizing plasma IGF-I levels in acromegaly. A multicenter study to reevaluate the future use of this modality in patients with acromegaly is warranted.

Acromegaly↗
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↗
PubMed1995

Automated localization of the prostate at the time of treatment using implanted radiopaque markers: technical feasibility.

PURPOSE: Prostate movement is a major consideration in the formation of target volumes for conformal radiation therapy of prostate cancer. The goal of this study was to determine the technical feasibility of using implanted radiopaque markers and digital imaging to localize the prostate at the time of treatment, thus allowing for reduction of the margin required for uncertainty in target position. METHODS AND MATERIALS: Radiopaque markers implanted around the prostate prior to treatment are visible on electronic radiographs generated with a portal imager or diagnostic imaging device. The locations of the images of these markers on the digital radiographs were automatically determined by a template-matching algorithm. The coordinates of the markers were found by projecting rays through the marker locations on orthogonal radiographs using a three-dimensional (3D) point-matching algorithm. Prostate and/or patient movement was inferred from the marker displacements. Images generated from known movements of a phantom with implanted markers were tested with this algorithm. Locations of markers from daily images of patients with implanted markers were determined by both manual and automatic techniques to determine the efficacy of automated localization on typical clinical images. RESULTS: Prostate movements can be automatically detected in a phantom using low-energy photons within 30 s after image acquisition and with a precision of better than 1 mm in translation and 1 degree in rotation (indistinguishable from the uncertainty in measuring precision). CONCLUSION: The studies show that on-line repositioning of the patient based on localization of the markers at the time of treatment is feasible, and may reduce the uncertainty in prostate location when combined with practical on-line repositioning techniques.

Feasibility Studies↗
PubMed1995

Three dimensional conformal radiotherapy for the treatment of prostate cancer: low risk of chronic rectal morbidity observed in a large series of patients.

PURPOSE: Three dimensional conformal radiotherapy (3D CRT) may provide a technique to increase the dose delivered to target tissues while sparing uninvolved normal structures. To evaluate the role of 3D treatment in reducing the treatment toxicity, we analyzed the chronic rectal morbidity observed in a large group of patients undergoing radiotherapy for prostate cancer. METHODS AND MATERIALS: From 1987 through 1992, 721 prostate cancer patients were treated with 3D CRT at the University of Michigan or Providence Hospital. All had axial computed tomography (CT) specifically for RT planning, multiple structures contoured on the axial images, and beam's-eye-view conformal beams edited to provide 3D dose coverage. Using current American Joint Commission (AJCC) staging, 537 patients had T1-T2 tumors, 123 had T3-T4 tumors, and 60 were treated postprostatectomy. Pelvic lymph nodes were treated in 462 patients. Prostate boosts were delivered with four-field axial, six-field axial, or four-field oblique, nonaxial fields. The median dose was 68.40 Gy (range 59.4-80.4). Median follow-up was 20.4 months; 175 were followed more than 3 years. All complications have been graded conservatively using the RTOG system. RESULTS: Using a Cox proportional hazard's model, patient age, T-stage, prescribed dose, pelvic treatment, and boost technique were analyzed. The factor most strongly related to risk of morbidity was dose (p = 0.05); however, the boost technique was also related: the four-field oblique field had the lowest relative risk. Most episodes of rectal morbidity have been mild: 82 Grade 1 or 2. There have been only 14 more serious complications including 12 Grade 3 and 2 Grade 4. The actuarial risk of a Grade 3 or 4 complication is 3% at 3 and 5 years. CONCLUSIONS: A very small proportion of patients treated with 3D CRT had significant rectal morbidity related to RT, supporting the use of conformal treatment planning and dose delivery as a mechanism to minimize complications in the treatment of prostate cancer.

Adenocarcinoma↗