Biomedical subjects

John C Roeske

Publications and source records attributed to John C Roeske.

At least 19 recordsLinked to original sources

PubMed2006

Optimization of the temporal pattern of radiation: an IMRT based study.

PURPOSE: To investigate how the temporal pattern of dose applied during a single-intensity modulated radiation therapy (IMRT) fraction can be arranged to maximize or minimize cell kill. METHODS AND MATERIALS: Using the linear-quadratic repair-time model and a simplified IMRT delivery pattern model, the surviving fraction of cells for a single fraction was calculated for all permutations of the dose delivery pattern for an array of clinically based IMRT cases. Maximization of cell kill was achieved by concentrating the highest doses in the middle of a fraction, while minimization was achieved by spreading the highest doses between the beginning and end. The percent difference between maximum and minimum cell kill (%Diff(min/max)) and the difference between maximum and minimum total doses normalized to 2 Gy/fx (deltaNTD(2 Gy)) was calculated for varying fraction durations (T), alpha/beta ratios, and doses/fx. RESULTS: %Diff(min/max) and deltaNTD(2 Gy) both increased with increasing T and with decreasing alpha/beta. The largest increases occurred with dose/fx. With alpha/beta = 3 Gy and 30 min/fx, %Diff(min/max) ranged from 2.7-5.3% for 2 Gy/fx to 48.6-74.1% for 10 Gy/fx, whereas deltaNTD(2 Gy) ranged from 1.2 Gy-2.4 Gy for 30 fractions of 2 Gy/fx to 2.3-4.8 Gy for 2 fractions of 10.84 Gy/fx. Using alpha/beta = 1.5 Gy, an analysis of prostate hypofractionation schemes yielded differences in clinical outcome based on the pattern of applied dose ranging from 3.2%-6.1% of the treated population. CONCLUSIONS: Rearrangement of the temporal pattern of dose for a single IMRT fraction could be used to optimize cell kill and to directly, though modestly, affect treatment outcome.

Algorithms↗

PubMed2006

Dosimetric predictors of acute hematologic toxicity in cervical cancer patients treated with concurrent cisplatin and intensity-modulated pelvic radiotherapy.

PURPOSE: To identify dosimetric parameters associated with acute hematologic toxicity (HT) and chemotherapy delivery in cervical cancer patients undergoing concurrent chemotherapy and intensity-modulated pelvic radiotherapy. METHODS AND MATERIALS: We analyzed 37 cervical cancer patients receiving concurrent cisplatin (40 mg/m(2)/wk) and intensity-modulated pelvic radiotherapy. Pelvic bone marrow (BM) was contoured for each patient and divided into three subsites: lumbosacral spine, ilium, and lower pelvis. The volume of each region receiving 10, 20, 30, and > or =40 Gy (V(10), V(20), V(30), and V(40), respectively) was calculated. HT was graded according to the Radiation Therapy Oncology Group system. Multivariate regression models were used to test associations between dosimetric parameters and HT and chemotherapy delivery. RESULTS: Increased pelvic BM V(10) (BM-V(10)) was associated with an increased Grade 2 or worse leukopenia and neutropenia (odds ratio [OR], 2.09; 95% confidence interval [CI], 1.24-3.53; p = 0.006; and OR, 1.41; 95% CI, 1.02-1.94; p = 0.037, respectively). Patients with BM-V(10) > or =90% had higher rates of Grade 2 or worse leukopenia and neutropenia than did patients with BM-V(10) <90% (11.1% vs. 73.7%, p < 0.01; and 5.6% vs. 31.6%, p = 0.09) and were more likely to have chemotherapy held on univariate (16.7% vs. 47.4%, p = 0.08) and multivariate (OR, 32.2; 95% CI, 1.67-622; p = 0.02) analysis. No associations between HT and V(30) and V(40) were observed. Dosimetric parameters involving the lumbosacral spine and lower pelvis had stronger associations with HT than did those involving the ilium. CONCLUSION: The volume of pelvic BM receiving low-dose radiation is associated with HT and chemotherapy delivery in cervical cancer patients undergoing concurrent chemoradiotherapy.

Adult↗

PubMed2006

A dosimetric analysis of intensity-modulated radiation therapy (IMRT) as an alternative to adjuvant high-dose-rate (HDR) brachytherapy in early endometrial cancer patients.

PURPOSE: To evaluate the role of intensity-modulated radiation treatment (IMRT) as an alternative to high-dose-rate (HDR) brachytherapy in the treatment of the vagina in postoperative early endometrial cancer patients after surgery. METHODS AND MATERIALS: Planning computed tomography (CT) scans of 10 patients previously treated with HDR were used in this study. In all cases, a dose of 700 cGy/fraction was prescribed at a distance of 0.5 cm from the cylinder surface. The same CT scans were then used in IMRT planning. In this paradigm, the vaginal cylinder represents a component of a hypothetical immobilization system that would be indexed to the linac treatment table. RESULTS: Our study showed that IMRT provided relatively lower rectal doses than HDR when treatment was prescribed at a distance of 0.5 cm away from the cylinder surface. Maximum rectal doses were lower with IMRT compared with HDR (average: 89.0% vs. 142.6%, respectively, p < 0.05). Moreover, the mean rectal dose was lower in IMRT plans compared with HDR plans with treatment prescribed either to the surface (average: 14.8% vs. 21.4%, respectively, p < 0.05) or to 0.5 cm (average: 19.6% vs. 33.5%, respectively, p < 0.05). IMRT plans had planning target volume (PTV) coverage comparable with HDR (average PTV minimum for treatment prescribed to 0.5 cm: 93.9% vs. 92.1%, p = 0.71, respectively) with less inhomogeneity (average PTV maximum: 110.8% vs. 381.6%, p < 0.05). CONCLUSION: Our dosimetric analysis suggests that when used in conjunction with a suitable immobilization system, IMRT may provide an alternative to HDR brachytherapy in women with early endometrial cancer after hysterectomy. However, more studies are needed to evaluate the clinical merit of the IMRT in these patients.

Brachytherapy↗

PubMed2006

The average number of alpha-particle hits to the cell nucleus required to eradicate a tumour cell population.

Alpha-particle emitters are currently being considered for the treatment of micrometastatic disease. Based on in vitro studies, it has been speculated that only a few alpha-particle hits to the cell nucleus are considered lethal. However, such estimates do not consider the stochastic variations in the number of alpha-particle hits, energy deposited, or in the cell survival process itself. Using a tumour control probability (TCP) model for alpha-particle emitters, we derive an estimate of the average number of hits to the cell nucleus required to provide a high probability of eradicating a tumour cell population. In simulation studies, our results demonstrate that the average number of hits required to achieve a 90% TCP for 10(4) clonogenic cells ranges from 18 to 108. Those cells that have large cell nuclei, high radiosensitivities and alpha-particle emissions occurring primarily in the nuclei tended to require more hits. As the clinical implementation of alpha-particle emitters is considered, this type of analysis may be useful in interpreting clinical results and in designing treatment strategies to achieve a favourable therapeutic outcome.

Alpha Particles↗

PubMed2006

Linac-based intensity modulated total marrow irradiation (IM-TMI).

Total body irradiation (TBI) has been used as a form of systemic therapy for the treatment of hematological malignancies and as a pre-conditioning regimen prior to bone marrow transplant. However, standard techniques are associated with both acute and chronic toxicities due to the large volumes of normal tissue irradiated. Intensity modulated radiation therapy (IMRT), with its ability to conform the high dose region to the shape of the target, offers a method to reduce radiation related sequelae and potentially allow for the delivery of higher than conventional doses. The goal of this study is to investigate the feasibility of a linac-based approach to intensity modulated total marrow irradiation (IM-TMI) and to discuss the challenges associated with its clinical implementation. The successful development of linac-based IM-TMI would represent advancement in the field of radiotherapy and potentially reduce the incidence and severity of complications associated with current TBI techniques.

Bone Marrow↗

PubMed2006

Intensity-modulated radiation therapy in gynecologic malignancies: current status and future directions.

Radiation therapy is used as either definitive or adjuvant therapy following surgery in many gynecologic malignancies. Though effective, radiation therapy is limited by the adverse sequelae that result from normal tissues receiving external-beam radiation. A novel approach, intensity-modulated radiation therapy, can overcome these limitations by sparing the tissue surrounding the malignancy through conforming the dose to the shape of the target in three dimensions. This review provides an overview of current use, published research, and ongoing studies of intensity-modulated radiation therapy.

Chemotherapy, Adjuvant↗

PubMed2005

Incorporation of SPECT bone marrow imaging into intensity modulated whole-pelvic radiation therapy treatment planning for gynecologic malignancies.

BACKGROUND AND PURPOSE: To incorporate single-photon emission computed tomography (SPECT) bone marrow (BM) imaging into the treatment planning process to reduce the volume of BM irradiated in gynecologic patients receiving intensity-modulated whole-pelvic radiation therapy (IM-WPRT). MATERIALS AND METHODS: A planning CT scan was obtained of a patient with early stage endometrial cancer. The same patient also underwent a Tc-99m sulfur colloid SPECT scan of the pelvis. Tc-99m sulfur colloid is sequestered by the macrophages in the BM thereby identifying areas of active (red) BM. Using image fusion software, the SPECT scan was aligned with the planning CT scan and used to delineate regions of active BM. An IMRT plan was then generated to provide coverage of the planning target volume (PTV) while sparing areas of active BM and other normal pelvic structures. RESULTS: The areas of high active BM density were observed predominantly in the lumbar vertebrae, sacrum and medial iliac crests. IMRT planning reduced the dose to these areas by 50% for doses greater than 30Gy compared to conventional planning. Furthermore, the IMRT plan did not compromise coverage of the PTV or sparing of normal tissues. CONCLUSIONS: Our results suggest that SPECT-BM imaging is a useful adjunct to IMRT planning in gynecologic patients undergoing IM-WPRT.

Bone Marrow↗

PubMed2005

Cell detection in phase-contrast images used for alpha-particle track-etch dosimetry: a semi-automated approach.

A novel alpha-particle irradiator has recently been developed that provides the ability to characterize cell response. The irradiator is comprised of a collimated, planar alpha-particle source which, from below, irradiates cells cultured on a track-etch material. Cells are imaged using phase-contrast microscopy before and following irradiation to obtain geometric information and survival rates; these can be used with data from alpha-particle track images to assess cell response. A key step in this process is determining cell location within the pre-irradiation images. Although this can be done completely by a human observer, the number of images requiring analysis makes the process time-consuming and tedious. To reduce the potential human error and decrease user interaction time, a semi-automated, computer-aided method of cell detection has been developed. The method employs a two-level adaptive thresholding technique to obtain size and position information about potential cell cytoplasms and nuclei. Proximity and geometry-based thresholds are then used to mark structures as cells. False-positive detections from the automated algorithm are due mostly to imperfections in the track-etch background, camera effects and cellular residue. To correct for these, a human observer reviews all detected structures, discarding false positives. When analysing two randomly selected cell dish image databases, the semi-automated method detected 92-94% of all cells and 94-97% of cells with a well-defined cytoplasm and nucleus while reducing human workload by 32-83%.

Algorithms↗

PubMed2005

A hybrid approach to reducing computed tomography metal artifacts in intracavitary brachytherapy.

PURPOSE: To develop a hybrid approach to reduce computed tomography (CT) metal artifacts caused by the Fletcher-Suit applicator. METHODS AND MATERIALS: Using the acquired raw projection data, the hybrid algorithm determines the separate contributions from the metal and non-metal objects. Next, reconstructions of metal and non-metal images are separately obtained from their estimated projections. A final image is formed by appropriately combining the individual images. Phantom and patient data are used to evaluate the performance of this method. RESULTS: CT images reconstructed by use of the standard filtered-backprojection (FBP) algorithm contain significant artifacts even for small metal objects. However, images reconstructed using the hybrid algorithm contain virtually no artifacts. For metal objects with complex structures, the hybrid algorithm can also yield images containing fewer severe streak artifacts than those reconstructed using the FBP algorithm alone. CONCLUSIONS: These studies demonstrate that the hybrid approach can effectively reduce CT metal artifacts caused by the Fletcher-Suit applicator.

Algorithms↗

PubMed2005

Setup errors in patients treated with intensity-modulated whole pelvic radiation therapy for gynecological malignancies.

Intensity-modulated whole pelvic radiation therapy (IM-WPRT) has decreased the incidence of gastrointestinal complications by reducing the volume of normal tissue irradiated in gynecologic patients. However, IM-WPRT plans result in steep dose gradients around the target volume, and thus accurate patient setup is essential. To quantify the accuracy of our patient positioning, we examined the weekly portal films of 46 women treated with IM-WPRT at our institution. All patients were positioned using a customized immobilization device that was indexed to the treatment table. Setup errors were evaluated by comparing portal images to simulation images using an algorithm that registers user-defined open curve segments drawn on both sets of film. The setup errors, which were separated into systematic and random components, ranged from 1.9 to 3.7 mm for the translations and 1.3 degrees to 4.4 degrees for the 2 in-plane translations. The systematic errors were all less than the respective random errors, with the largest error in the anterior/posterior direction. In addition, there was no correlation between the magnitude of these errors and patient-specific factors (age, weight, height). In the future, we will investigate the effect of these setup errors on the delivered dose distribution.

Algorithms↗

PubMed2005

Predictors of tumor control in patients treated with linac-based stereotactic radiosurgery for metastatic disease to the brain.

OBJECTIVE: The objective of this study was to determine predictive factors for local control (LC) of brain metastases (BM) treated with Linac-based stereotactic radiosurgery (LB-SRS). METHODS: Between January 1994 and July 2001, 80 patients (126 BM) underwent LB-SRS. All patients had follow-up imaging with computed tomography (40%) or magnetic resonance imaging (60%). Most patients had either lung (41%) or renal cell (20%) cancer. The median SRS prescription dose was 18 Gy (range, 10-21 Gy). Most patients (86%) also received whole-brain radiotherapy (WBRT). LC was defined as the absence of enlargement of the BM on follow-up scans. Actuarial LC analyses were performed by the method of Kaplan-Meier and compared with the log-rank test. Factors analyzed included histology, volume, prescription dose, maximum and minimum tumor dose, target volume ratio, number of arcs and isocenters, total degrees, and WBRT. Multivariate analysis was accomplished. RESULTS: At a median follow up of 8.8 months, 11 BM failed (8.7%). The 1-and 2-year actuarial LC rates were 88.6% and 77.2%, respectively. The most significant factors correlated with LC were prescription (P = 0.0004) and minimum tumor (P = 0.002) doses, and tumor volume (P = 0.04). On multivariate analysis, the sole factor correlated with LC was minimum tumor dose (P = 0.03). CONCLUSION: Our results confirm that LB-SRS is associated with excellent LC rates in the majority of patients treated. However, particular attention should be given to minimum target dose to ensure optimal outcome.

Adult↗

PubMed2005

Survey of resident education in intensity-modulated radiation therapy.

Intensity-modulated radiation therapy (IMRT) has been gaining increasing popularity among practicing physicians in the U.S., but the extent to which radiation oncology residents are taught the principles of this technology and are trained to use IMRT remains unknown. In this paper, we assessed the current level of resident education in IMRT in the United States. Chief residents at all 77 accredited radiation oncology programs were sent a 13-question survey addressing formal didactics and hands-on experience in IMRT. The survey assessed the frequency, subject, and format of IMRT didactics. Questions also addressed the number of IMRT patients and anatomical sites treated, resident involvement in the IMRT process, and the intent of IMRT use. Finally, residents were asked for their opinions on their IMRT education. Sixty-one surveys (79%) were completed. Overall, forty-three respondents (71%) reported receiving formal IMRT didactics, with nearly one-third reporting extensive didactics (> or = 3 lectures/seminars et cetera per year). The most common didactic formats were lectures (95%) and journal clubs (63%), most commonly supervised by physicists (98%). Involvement by physicians and radiobiologists were reported by 63% and 7% of respondents, respectively. Overall, 87% of respondents had hands-on IMRT training, with nearly one-half having treated > 25 patients. The most common sites treated were head and neck (94%) and prostate (81%). Involvement in all aspects of the IMRT process was common, particularly target and tissue delineation (98%) and plan evaluation (93%). Most respondents (79%) with hands-on experience reported receiving formal didactics. However, nearly one-third received no or only minimal formal didactics. The percentage of respondents desiring increased IMRT didactics and hands-on experience were 70% and 47%, respectively. Our results suggest that the great majority of radiation oncology residents in the United States are currently exposed to didactics and hands-on training in IMRT. Areas of potential improvement include increased involvement of physicians and radiobiologists in formal IMRT didactics.

Health Care Surveys↗

PubMed2004

Intensity-modulated radiotherapy and the Internet.

BACKGROUND: The objective of the current study was to evaluate the content and quality of patient-oriented information regarding intensity-modulated radiotherapy (IMRT) on the Internet. METHODS: IMRT websites were identified by reviewing the first 50 uniform resource locators on 5 search engines using the search terms IMRT and intensity modulated radiation therapy. Each site was evaluated by three observers for informational content, presentation, accuracy, and balance. A score of low, moderate, or high was assigned to each category based on a predefined scoring system. An overall score was assigned to each site, ranging from -35 to 100 points. RESULTS: Seventy-seven patient-oriented IMRT websites were identified (45% private, 21% academic, and 18% commercial). Most sites (58%) had a low level of informational content, with information on fundamental aspects of IMRT planning (target delineation and inverse planning) appearing on < 50% of sites. The most commonly discussed tumors were genitourinary (65%) and head and neck (53%) lesions. Few sites, however, described the potential benefits of IMRT (toxicity and tumor control). Most sites (82%) used patient-appropriate language. False and/or misleading information was seen on 42% of sites and was equally common on academic, private, and commercial sites. Balance statements were present on 24% of sites (most of which were commercial). The median overall score was 20 points (range, -25 to 70 points). The median overall scores for academic, private, commercial, and other sites were 10, 20, 25, and 20 points, respectively (P = 0.26). CONCLUSIONS: In general, the content and quality of patient-oriented information regarding IMRT on the Internet were poor. Patients and their physicians need to be aware of these problems when selecting treatment courses.

Humans↗

PubMed2004

Intensity-modulated radiotherapy in treatment of pancreatic and bile duct malignancies: toxicity and clinical outcome.

PURPOSE: To assess the efficacy and toxicity of intensity-modulated radiotherapy (IMRT) in pancreatic and bile duct (cholangiocarcinoma) malignancies. METHODS AND MATERIALS: Twenty-five patients with pancreatic and bile duct cancer were treated with IMRT. Twenty-three received concurrent 5-fluoruracil. One patient with a pancreatic primitive neuroectodermal tumor received concurrent etoposide and ifosfamide. Eight patients had resected tumors, and 17 had unresectable primary (n = 14) or recurrent (n = 3) tumors. Six patients underwent treatment planning with conventional three-dimensional four-field techniques for dosimetric comparison with IMRT. RESULTS: Compared with conventional RT, IMRT reduced the mean dose to the liver, kidneys, stomach, and small bowel. IMRT was well tolerated, with 80% experiencing Grade 2 or less acute upper GI toxicity. At a median follow-up of 10.2 months, no resected patients had local failure, and only 1 of 10 assessable patients with unresectable cancer had local progression. The median survival and distant metastasis-free survival of the 24 patients with adenocarcinoma was 13.4 and 7.3 months, respectively. Grade 4 late liver toxicity occurred in 1 patient surviving >5 years. The remainder of the assessable patients experienced no (n = 9) or Grade 1 (n = 4) late toxicity. CONCLUSION: In this hypothesis-generating analysis, the acute and chronic toxicity profile with IMRT in the treatment of pancreatic and bile duct cancer was encouraging. Local control was not compromised, despite efforts to increase conformality and avoid doses to normal structures. Distant failure remains a major obstacle in pancreatic cancer.

Adenocarcinoma↗

PubMed2004

Intensity-modulated radiation therapy in gynecologic malignancies.

Radiation therapy occupies an important role in the treatment of gynecologic malignancies. Unfortunately, traditional approaches result in the irradiation of large volumes of normal tissues exposing patients to many toxicities and precluding dose escalation in select patients. A novel approach to the planning and delivery of radiation therapy, known as intensity-modulated radiation therapy (IMRT), has been introduced. Unlike conventional approaches, IMRT conforms the prescription dose to the shape of the target in three dimensions, thus sparing the surrounding normal tissues. Multiple studies have demonstrated the clear superiority of IMRT planning in these patients in terms of normal tissue sparing. Promising clinical results have also been published, suggesting that IMRT reduces the incidence of acute and chronic toxicity in these women. Ongoing studies are focusing on tumor control and patient outcome. Although further work is needed, these results suggest that IMRT may represent a major advancement in the planning and delivery of radiation therapy in patients with gynecologic malignancies.

Brachytherapy↗

PubMed2004

Biological effective dose for comparison and combination of external beam and low-dose rate interstitial brachytherapy prostate cancer treatment plans.

We report a methodology for comparing and combining dose information from external beam radiotherapy (EBRT) and interstitial brachytherapy (IB) components of prostate cancer treatment using the biological effective dose (BED). On a prototype early-stage prostate cancer patient treated with EBRT and low-dose rate I-125 brachytherapy, a 3-dimensional dose distribution was calculated for each of the EBRT and IB portions of treatment. For each component of treatment, the BED was calculated on a point-by-point basis to produce a BED distribution. These individual BED distributions could then be summed for combined therapies. BED dose-volume histograms (DVHs) of the prostate, urethra, rectum, and bladder were produced and compared for various combinations of EBRT and IB. Transformation to BED enabled computation of the relative contribution of each modality to the prostate dose, as the relative weighting of EBRT and IB was varied. The BED-DVHs of the prostate and urethra demonstrated dramatically increased inhomogeneity with the introduction of even a small component of IB. However, increasing the IB portion relative to the EBRT component resulted in lower dose to the surrounding normal structures, as evidenced by the BED-DVHs of the bladder and rectum. Conformal EBRT and low-dose rate IB conventional dose distributions were successfully transformed to the common "language" of BED distributions for comparison and for merging prostate cancer radiation treatment plans. The results of this analysis can assist physicians in quantitatively determining the best combination and weighting of radiation treatment modalities for individual patients.

Algorithms↗

PubMed2004

Simulation of binary methods for the microdosimetric analysis of cell survival after alpha-particle irradiation: ability to distinguish between different models.

Analysis of cell survival after alpha-particle irradiation must account for the distribution in the amounts of energy deposited in each cell nucleus. Microdosimetric computations are usually used to determine these distributions. Irradiation with microbeams and other modern techniques has made these computations unnecessary for certain cell geometries. These techniques allow the survival of individual cells to be correlated with the amount of radiation delivered to individual cell nuclei. However, to maintain the individuality of data generated for each cell, new methods of analysis are required. In this study, we propose the use of binary methods. Each cell is regarded as a Bernoulli trial with a different probability for success (colony formation). Parameter values of the survival model are chosen to maximize the likelihood of the observed outcome. To evaluate this method, simulated data for 500, 5000 and 50,000 cells irradiated by alpha particles are analyzed along with the associated outcome for four different cell survival models. Each survival model has a different dependence on the radius of the cell nucleus. These results indicate that the model that was simulated has the highest likelihood value in all cases. However, the ability to distinguish between competing models is present only for a larger numbers of cells.

Alpha Particles↗

PubMed2003

Intensity-modulated radiotherapy as a means of reducing dose to bone marrow in gynecologic patients receiving whole pelvic radiotherapy.

PURPOSE: To evaluate intensity-modulated whole pelvis radiotherapy (IM-WPRT) (with bone marrow [BM] as a planning constraint) as a means to reduce the volume of pelvic BM irradiated. METHODS AND MATERIALS: Ten women with cervical or endometrial cancer previously treated using IM-WPRT were selected for this analysis. Using the treatment planning CT scan, the clinical target volume was defined to encompass the gross tumor, parametrial tissues, uterus (if present), and regional lymph nodes. The clinical target volume was expanded by a 1-cm margin to form the planning target volume (PTV). The bladder, rectum, small bowel, and pelvic BM were delineated in each patient. Three plans were created for each patient: a standard four-field WPRT plan, an IM-WPRT treatment plan designed to conform the dose to the PTV while minimizing dose to the normal tissues (excluding BM), and a BM-sparing (BMS) IM-WPRT plan that included the BM as an additional treatment planning constraint. Dose-volume histograms for the PTV, small bowel, and BM were compared for each patient. RESULTS: For each of the 10 patients, BMS IM-WPRT treatment plans demonstrated a significant reduction of the volume of BM receiving >40% (18 Gy) of the prescription dose (45 Gy) compared with both IM-WPRT and four-field treatment. On average, BMS IM-WPRT resulted in only 60% of the BM volume irradiated to >50% of the dose compared with 87.4% (p <0.001) of the BM volume in a four-field plan and 75.7% (p < 0.003) of the volume in an IM-WPRT plan. Furthermore, the BMS IM-WPRT plans resulted in significant sparing of all other normal tissues that was comparable to the original IM-WPRT. In all 10 cases, the BMS IM-WPRT treatment plan did not result in any significant differences in the PTV and small bowel dose-volume histograms compared with the IM-WPRT treatment plans. CONCLUSION: BMS IM-WPRT significantly reduces the volume of pelvic BM irradiated compared with conventional WPRT. In addition, BMS IM-WPRT did not compromise the improvements previously seen in IM-WPRT treatment plans that did not consider BM. Clinical studies are necessary to assess the significance of BMS IM-WPRT in reducing hematologic toxicity.

Bone Marrow Diseases↗