Modern Radiation Treatment Techniques Research Articles

The Tissue-Sparing Effect of Spatially Fractionated X-rays for Maintaining Spermatogenesis: A Radiobiological Approach for the Preservation of Male Fertility after Radiotherapy

Radiotherapy can result in temporary or permanent gonadal toxicity in male cancer patients despite the high precision and accuracy of modern radiation treatment techniques. Previous radiobiological studies have shown an effective tissue-sparing response in various tissue types and species following exposure to spatially fractionated radiation. In the present study, we used an ex vivo mouse testicular tissue culture model and a conventional X-ray irradiation device to evaluate the tissue-sparing effect (TSE) of spatially fractionated X-rays for the protection of male fertility from radiotherapy-related adverse effects. We revealed a significant TSE for maintaining spermatogenesis in the ex vivo testes model following spatially fractionated X-ray irradiation. Moreover, we experimentally propose a possible mechanism by which the migration of spermatogonial cells, from the non-irradiated areas to the irradiated ones, in irradiated testicular tissue, is essential for the TSE and maintaining spermatogenesis. Therefore, our findings demonstrate that the control of TSE following spatially fractionated X-rays in the testes has a considerable potential for clinical application. Interdisciplinary research will be essential for further expanding the applicability of this method as an approach for the preservation of male fertility during or after radiotherapy.

Enhancement in the kV Portal Image Contrast Using Depth Normalization for Accurate Patient Localization

The X-ray imaging modality has played an important role in the daily verification of a patient’s position for accurate radiation treatment (RT), especially in modern RT techniques that require highly precise patient localization. Although cone-beam computer tomography (CBCT) has already been introduced to the RT field, two-dimensional (2D) X-ray portal imagers have been more widely used than CBCT for the daily check of patient localization owing to the lower patient exposure and time consumption. However, the 2D imager practically provide a lower bone-tissue contrast than CBCT. Thus, we propose a method that enhances the image contrast of daily acquired 2D images by using just one CBCT scan during an entire RT course. This method operates on the basis of the depth normalization (DN) technique and requires no artificial data manipulation such as image post-processing filters. We implemented the algorithm for the portal images of a cylindrical phantom and three patients. From DN results, the image contrast for the phantom and the patients increased by factors of 26.3 and 13.4 on average, and their contrast-to-noise ratios were maintained at differences of 8.6% and 7.7% on average, respectively. Moreover, the DN method provided a stronger contrast enhancement at lower doses that could suppress the imaging exposure and thus improve the patient’s safety. Therefore, the verification of RT patient localization is expected to be performed more efficiently and accurately by using the DN method.

Testicular seminoma: Scattered radiation dose to the contralateral testis in the modern era

PurposeLimited data exist on testicular dose measurements using modern radiation treatment techniques and volumes for testicular seminoma. The aim of this study was to report the testicular dose using in vivo measurements in men with testicular seminoma receiving abdominopelvic radiation therapy (APRT) and a modified dog-leg field with and without gonadal shielding. Methods and materialsMen with histologically confirmed testicular seminoma, either newly diagnosed stage II disease or isolated retroperitoneal relapse on surveillance for stage I disease, treated with APRT had testicular dose measurements recorded using MOSFET dosimeters. Those patients wishing to preserve fertility underwent radiation treatment with daily gonadal shielding. Factors that may influence testicular dose including field size, distance of the remaining testis from the radiation field, and patient separation, were also measured. ResultsMeasurements were performed for 16 men; 10 with gonadal shielding and 6 without. The mean measured dose to the testis in the patients with gonadal shielding was 2.6 cGy (standard error, 0.75; range, 0-13) compared with 28.6 cGy (standard error, 12.6; range, 0-86) in the unshielded group for a 20-fraction treatment. ConclusionsThe use of gonadal shielding during APRT with a modified dog-leg technique results in a low testicular dose that is below the likely threshold for impaired spermatogenesis. In those men wishing to preserve fertility, we recommend the use of gonadal shielding, even with the use of modern radiation therapy techniques.

9th International Conference on 3D Radiation Dosimetry

IC3DDose 2016 - 9th International Conference on 3D Radiation DosimetryPrefaceIt was a great pleasure to welcome participants to IC3DDose 2016, the 9th International Conference on 3D Radiation Dosimetry, held from 7–10 November 2016 in Galveston, Texas.The series of conferences has evolved considerably during its history. At the first conference, DOSGEL’99, the discussion centered around gel dosimetry. Held in Lexington, Kentucky in 1999, it was timed to coincide with the American Association of Physicists in Medicine (AAPM) Annual Meeting in Nashville, Tennessee. It was my honour to organize that first conference, and it was once again my honour to organize the 9th conference in the series now known as IC3DDose which was held in Galveston, Texas.As was the case with recent IC3DDose conferences, the topic has broadened considerably beyond gel dosimetry. Not only have newer 3D volumetric dosimeters appeared on the scene, but novel electronic dosimetry systems and software that generate quasi-3D dose information have also. These changes have tracked advances in radiation oncology as techniques such as IMRT, VMAT, and IGRT have become almost ubiquitous. At the same time, dynamic treatments including gating and tracking now enjoy widespread use. Novel treatment technologies have appeared with perhaps the most disruptive being combined MR imaging-treatment units such as the ViewRay MR-cobalt unit and the Elekta/Philips MR-Linac.The potential benefits offered by 3D dosimetry were explored, compared and evaluated during IC3DDose 2016. Novel and improved readout techniques, some of which take advantage of the contemporary treatment environment and new QA systems and procedures, as well as other aspects of clinical dosimetry were well represented in the program.Over the past several years, the importance of safety in radiation therapy has been highlighted. The benefits of 3D dosimetry in contributing to safe and accurate treatments cannot be overstated. The implementation of new dosimetry procedures also requires careful attention to safety, accuracy and thorough validation. Therefore, the aims of IC3DDose 2016 were similar to those from previous conferences:• to enhance the quality and accuracy of radiation therapy treatment through improved clinical dosimetry;• to investigate and understand the dosimetric challenges of modern radiation treatment techniques;• to provide a forum to discuss the latest research and developments in 3D and advanced radiation dosimetry; and,• to energize and diversify dosimetry research and clinical practice by encouraging interaction and synergy among advanced, 3D and semi-3D dosimetry techniques.IC3DDose 2016 was a stimulating and exciting conference and the program included substantial contributions to scientific progress in the field.Thanks are offered to those who helped make the conference possible. The Scientific Committee, led by Sam Beddar, conducted thorough peer reviews of submitted papers in a timely manner and made valuable and thoughtful suggestions for improvements. The Committee also contributed to the planning of the meeting and to the organization of the program. The distinguished invited speakers who agreed to present are thanked for the extra work they performed to design and prepare educational and timely talks. My colleagues at MD Anderson Cancer Center are also thanked for their contributions to the planning of the meeting, managing the logistics, and generally helping to make sure that the conference was a success.Geoff IbbottMD Anderson Cancer CenterINTERNATIONAL SCIENTIFIC COMMITTEESam Beddar (Chair) (USA)Claus Andersen (Sweden)Sven Back (Sweden)Clive Baldock (Conference Proceedings Editor) (Australia)Crister Ceberg (Sweden)Yves de Deene (Australia)Simon Doran (United Kingdom)Anna Karlsson Hauer (Sweden)Andrew Jirasek (Canada)Kevin Jordan (Canada)Martin Lepage (Canada)Daniel Low (USA)Mark Oldham (USA)John Schreiner (Canada)Cheng-Shie Wuu (USA)LOCAL ORGANIZING COMMITTEEGeoffrey Ibbott (Chair)Dana GarrisonKayla WhiteHannah LeeYvonne RoedMitchell CarrollSam Beddar

Radiation therapy for retroperitoneal sarcoma

Retroperitoneal sarcomas (RPS) are rare tumours with an annual reported incidence of 2.7 per million persons. In spite of improvements in both diagnostic imaging and therapeutic strategies, patients afflicted by RPS still have poor prognoses. There are currently many different therapeutic strategies for these rare tumours and combining several different multi-modality strategies have not proved to have superior long-term clinical results. This review analyses the available published data and discusses multi-modality management of this rare entity. In particular, the role of radiation therapy, treatment-related side effects and the use of modern radiation treatment techniques will be discussed. A comprehensive literature search was conducted using PubMed in January 2011. Relevant international articles published from January 1980 to January 2011 were assessed. The keywords for search purposes were: retroperitoneum, sarcoma, radiotherapy, and radiation therapy. The search was limited to articles published in English. All articles were read in full by the authors and selected for inclusion based on relevance to this article. The addition of radiation therapy (RT) to wide surgical excision for RPS has improved local control rates when compared with surgery alone. Preoperative RT is preferred over postoperative RT. New types and delivery techniques in radiation therapy could further improve patient outcomes. Emerging therapies that employ charged particles (such as protons and carbon ions) are expected to be superior in sparing of normal tissues and efficacy over conventional photon therapy radiation, due to their physical and radiobiological properties.

Modern radiation treatment techniques for patients with early stage Hodgkin lymphoma

Modern radiation treatment techniques for patients with early stage Hodgkin lymphoma

Treatment of radiation-induced mucocutaneous toxicity

During radiotherapy 80% to 90% of all patients will develop some degree of inflammation symptoms, such as erythema, dry or wet desquamation, skin folds, or mucositis depending on radiation-and patient-related factors and the extent of irradiated skin or mucosal areas. Up to now radiation induced local reactions represent still an important toxicity factor. Cutaneous and mucosal side effects may reduce the patient's compliance and can be limiting factors to follow radiotherapy protocols. Therefore, there is a high need for effective prophylactic and therapeutic treatments. Basically, guidelines recommend the avoidance of mechanical, chemical and thermal irritants, especially the exposure to high temperatures. To delay onset of radiodermatitis various preventive topicals may be applied like aqueous cream formula with or without antioxidative agents. In general, the treatment of radiodermatitis primarily should maintain moisture and skin permeability and consists of hydrophilic creams, antioxidative and anti-inflammatory topicals. Hydrocolloid dressings may reduce and improve wound healing in grade 2 and 3 reactions. Supportive therapy of radiation-induced mucositis includes the maintenance of oral care protocols and adequate nutrition during the course of treatment. A sufficient oral health status is one of the most important factors for prevention of severe oral complications. The MASCC guidelines recommend furthermore the use of non-medicated rinses with saline or sodium bicarbonate 4 to 6 times daily. Further approaches suggest the use of local anaesthetics and systemic analgesics for severe mucositis. Besides local preventive agents and supportive care protocols, modern radiation treatment techniques remain the most promising intervention in reducing the degree of skin reactions.

MO-F-BRA-03: Secondary Neutron Dose Measurements Using CR-39 Detectors in Photon and Proton Radiotherapy

Purpose: It is assumed that modern radiation treatment techniques such as intensity‐modulated radiotherapy(IMRT), volumetric‐modulated arc therapy (VMAT) and protonradiotherapy are increasing the cancer cure rates and simultaneously reducing side effects. But there are also concerns about radiation‐induced malignancies caused by secondary neutronradiation, in particular, for younger patients. The aim of this study was to measure secondary neutrondose for a radiotherapy patient during typical treatments. Methods: In order to evaluate the neutrondose for a patient, an anthropomorphic Alderson‐Rando phantom was used. The measurements were performed using CR‐39 etched track detectors, placed inside and on the surface of the phantom, giving a three dimensional dose distribution and the organ doses. The neutrondose was compared with respect to treatment technique, therapy machine and radiation quality. The CR‐39 detectors were calibrated using an Am‐Be neutron source and an ICRU cubic phantom. The series of measurements included photon irradiations delivered by treatment machines of the manufacturers Varian, Elekta and Siemens and the treatment techniques 3D‐conformal, IMRT and VMAT. The proton irradiations were performed using active spot scanning and passive scattering techniques. Results: The doses were determined in terms of equivalent dose. In addition, effective dose was calculated using organ specific weighting factors of the ICRP. The effective doses for the complete course of treatment were 3.8 mSv, 3.0 mSv, 3.4 mSv, 0.7 mSv, 2.8 mSv, 20.3 mSv and 26.8 mSv for Varian 3D‐conformal, Varian IMRT, Varian VMAT, Elekta IMRT, Siemens IMRT, spot scanning protons and passively scattered protons, respectively. Conclusions: The differences in neutrondose between the different treatment techniques for photons were not large. However, Elekta machines produce considerably lower neutrondose than Varian and Siemens machines. For protontreatments,neutrondose is higher in general and apparently higher for scattered compared to spot scanned protons.

Involved-Node Radiotherapy and Modern Radiation Treatment Techniques in Patients With Hodgkin Lymphoma

To assess the clinical outcome of the involved-node radiotherapy (INRT) concept using modern radiation treatments (intensity-modulated radiotherapy [IMRT] or deep-inspiration breath-hold radiotherapy [DIBH) in patients with localized supradiaphragmatic Hodgkin lymphoma. All but 2 patients had early-stage Hodgkin lymphoma, and they were treated with chemotherapy prior to irradiation. Radiation treatments were delivered using the INRT concept according to European Organization for Research and Treatment of Cancer guidelines. IMRT was performed with the patient free-breathing. For the adapted breath-hold technique, a spirometer dedicated to DIBH radiotherapy was used. Three-dimensional conformal radiotherapy was performed with those patients. Fifty patients with Hodgkin lymphoma (48 patients with primary Hodgkin lymphoma, 1 patient with recurrent disease, and 1 patient with refractory disease) entered the study from January 2003 to August 2008. Thirty-two patients were treated with IMRT, and 18 patients were treated with the DIBH technique. The median age was 28 years (range, 17-62 years). Thirty-four (68%) patients had stage I - (I-IIA) IIA disease, and 16 (32%) patients had stage I - (I-IIB) IIB disease. All but 3 patients received three to six cycles of adriamycin, bleomycin, vinblastine, and dacarbazine (ABVD). The median radiation doses to patients treated with IMRT and DIBH were, respectively, 40 Gy (range, 21.6-40 Gy) and 30.6 Gy (range, 19.8-40 Gy). Protection of various organs at risk was satisfactory. Median follow-up was 53.4 months (range, 19.1-93 months). The 5-year progression-free and overall survival rates for the whole population were 92% (95% confidence interval [CI], 80%-97%) and 94% (95% CI, 75%-98%), respectively. Recurrences occurred in 4 patients: 2 patients had in-field relapses, and 2 patients had visceral recurrences. Grade 3 acute lung toxicity (transient pneumonitis) occurred in 1 case. Our results suggest that patients with localized Hodgkin lymphoma can be safely and efficiently treated using the INRT concept and modern radiation treatment techniques such as IMRT and DIBH.

Investigation of radiological properties and water equivalency of PRESAGE® dosimeters

PRESAGE is a dosimeter made of polyurethane, which is suitable for 3D dosimetry in modern radiation treatment techniques. Since an ideal dosimeter is radiologically water equivalent, the authors investigated water equivalency and the radiological properties of three different PRESAGE formulations that differ primarily in their elemental compositions. Two of the formulations are new and have lower halogen content than the original formulation. The radiological water equivalence was assessed by comparing the densities, interaction probabilities, and radiation dosimetry properties of the three different PRESAGE formulations to the corresponding values for water. The relative depth doses were calculated using Monte Carlo methods for 50, 100, 200, and 350 kVp and 6 MV x-ray beams. The mass densities of the three PRESAGE formulations varied from 5.3% higher than that of water to as much as 10% higher than that of water for the original formulation. The probability of photoelectric absorption in the three different PRESAGE formulations varied from 2.2 times greater than that of water for the new formulations to 3.5 times greater than that of water for the original formulation. The mass attenuation coefficient for the three formulations is 12%-50% higher than the value for water. These differences occur over an energy range (10-100 keV) in which the photoelectric effect is the dominant interaction. The collision mass stopping powers of the relatively lower halogen-containing PRESAGE formulations also exhibit marginally better water equivalency than the original higher halogen-containing PRESAGE formulation. Furthermore, the depth dose curves for the lower halogen-containing PRESAGE formulations are slightly closer to that of water for a 6 MV beam. In the kilovoltage energy range, the depth dose curves for the lower halogen-containing PRESAGE formulations are in better agreement with water than the original PRESAGE formulation. Based on the results of this study, the new PRESAGE formulations with lower halogen content are more radiologically water equivalent overall than the original formulation. This indicates that the new PRESAGE formulations are better suited to clinical applications and are more accurate dosimeters and phantoms than the original PRESAGE formulation. While correction factors are still needed to convert the dose measured by the dosimeter to an absorbed dose in water in the kilovoltage energy range, these correction factors are considerably smaller for the new PRESAGE formulations compared to the original PRESAGE and the existing polymer gel dosimeters.

Reply to J.L. Oh et al

We thank Drs Oh and Buchholz for their letter regarding our review article, emphasizing several important issues on the treatment of internal mammary nodes (IMNs) in breast cancer. As the letter suggests and as we summarized in the article, multiple studies consistently show that a significant minority of patients with breast cancer have pathologic IMN involvement, and the risk of IMN involvement increases in patients with medial tumors and/or positive axillary nodes. While it seems reasonable based on these data to consider IMN irradiation for patients with medial tumors and/or positive axillary nodes, evidence directly linking IMN treatment to a survival benefit is not currently available. Randomized trials evaluating IMN dissection did not show a survival benefit, although they were largely underpowered, and retrospective studies evaluating patients with versus without IMN treatment have shown mixed results. We eagerly await results from more recent randomized trials assessing the potential benefit of IMN irradiation to help shed light on this question. Before these data become available, considerations regarding IMN treatment must include its potential therapeutic benefits balanced against a possible risk of increased morbidity. Drs Oh and Buchholz highlight modern radiation treatment techniques for the IMN, including their elegant split-electron beam technique. Indeed, while the older radiation techniques using an anterior photon field or “Hockey Stick” technique to treat the IMN exposed a significant portion of the heart to radiation treatment, modern computed tomography–based planning have allowed the development of multiple techniques that cover the IMN but minimize radiation dose to the heart. As the letter correctly points out, the Danish Breast Cancer Cooperative Group trials 82b and 82c, which used an electron technique to treat the IMN, showed no increase in the rate of deaths from ischemic heart disease (0.9%) in patients randomly assigned to the radiation therapy arm. We agree that current concerns about potential cardiac morbidity and mortality risk from IMN irradiation should not be completely based on outcomes of outdated radiation techniques from 20 to 30 years ago. More studies are needed to evaluate the long-term cardiac effects of modern radiation techniques. Specifically, an especially important area of research is studies that help clarify the relationship between dose/volume of heart-irradiated and long-term cardiac morbidity/mortality, which is not currently well understood. In addition, how radiation treatment to specific portions of the heart changes cardiac physiology also needs to be defined. Such information could allow IMN irradiation to be administered even more safely.

9227 Involved node radiotherapy (INRT) and modern radiation treatment techniques in patients with Hodgkin lymphoma

Doxorubicin/bleomycin/vinblastine/dacarbazine (ABVD) plus involved-field radiation therapy (IFRT) is the gold-standard treatment for early and advanced stages of Hodgkin lymphoma (HL). We evaluated the outcomes of patients according to prognosis at diagnosis and over time to determine who achieved complete remission (CR).Treatment-naive patients under the age of 75 years at all stages of HL were eligible. The favorable group (FG) contained patients with stage IA-IIIA disease without bulky areas who achieved CR after the third cycle of ABVD. They received only IFRT at 25 Gy. Patients in the unfavorable group (UG) exhibited stages IIIB and IV HL. The UG also included all patients with bulky disease and the subset of the FG without CR after 3 cycles of ABVD, ie, slow responders (FGSR). The UG received 6 cycles of ABVD plus IFRT at 30 Gy to bulky areas at diagnosis or to those areas remaining positive after the third cycle of ABVD.In total, 584 patients were evaluable: 285 of them belonged to the FG, and 299 to the UG. Rates of CR were 98% and 85% for the FG and the UG, respectively (P < .001). Sixty patients in the FG received 6 cycles of ABVD because they had not achieved CR after 3 cycles (ie, the FGSR subgroup). The 5-year event-free survival rate was 89% for the FG, 66% for the FGSR, and 72% for the UG (P < .001). The overall survival at 5 years was significantly better for the FG (98%) than for the FGSR (87%) and the UG (88%; P < .001).Patients from the FG demonstrated excellent outcomes compared with those from the FGSR and UG, despite receiving less chemotherapy and fewer doses of IFRT.

The Impact of IMRT and Proton Radiotherapy on Secondary Cancer Incidence

There is concern about the increase of radiation-induced malignancies with the application of modern radiation treatment techniques such as intensity-modulated radiotherapy (IMRT) and proton radiotherapy. Therefore, X-ray scatter and neutron radiation as well as the impact of the primary dose distribution on secondary cancer incidence are analyzed. The organ equivalent dose (OED) concept with a linear-exponential and a plateau dose-response curve was applied to dose distributions of 30 patients who received radiation therapy of prostate cancer. Three-dimensional conformal radiotherapy was used in eleven patients, another eleven patients received IMRT with 6-MV photons, and eight patients were treated with spot-scanned protons. The treatment plans were recalculated with 15-MV and 18-MV photons. Secondary cancer risk was estimated based on the OED for the different treatment techniques. A modest increase of 15% radiation-induced cancer results from IMRT using low energies (6 MV), compared to conventional four-field planning with 15-MV photons (plateau dose-response: 1%). The probability to develop a secondary cancer increases with IMRT of higher energies by 20% and 60% for 15 MV and 18 MV, respectively (plateau dose-response: 2% and 30%). The use of spot-scanned protons can reduce secondary cancer incidence as much as 50% (independent of dose-response). By including the primary dose distribution into the analysis of radiation-induced cancer incidence, the resulting increase in risk for secondary cancer using modern treatment techniques such as IMRT is not as dramatic as expected from earlier studies. By using 6-MV photons, only a moderate risk increase is expected. Spot-scanned protons are the treatment of choice in regard to secondary cancer incidence.

PRESAGE - A Promising New Material for 3D Dosimetry

Purpose/Objective: Comprehensive treatment verification is a key pre-requisite to achieving high quality and accuracy of modern radiation treatment techniques including IMRT and IGRT. The complexity of these techniques has created a gross need for a practical and accurate 3D dosimeter that can comprehensively measure dose distributions in 3D. PRESAGE is a new machineable plastic material with promising characteristics as a 3D dosimeter. Chiefly, insensitivity to environment (oxygen), ability to machine the dosimeter for customized applications, and a sensitive dose response to ionizing radiation.

Comparison of bat system and a new 3D trans-abdominal ultrasound-based image-guided system for prostate daily localization during external beam radiotherapy

Combined with modern radiation treatment techniques, such as 3DCRT or IMRT, reduction of PTV margins in prostate cancer external beam radiotherapy [EBRT] reduces dose to nearby normal tissues and could potentially allow an increased radiation dose to the prostate. However, tight margins could lead to geographical misses due to daily prostate displacement. The purpose of this study was to compare 2 distinctly different image-guided verification methods for prostate alignment during daily radiotherapy. A prospective clinical trial was conducted whereas prostate displacements were measured in 40 patients undergoing daily EBRT for prostate cancer. Comparison was made between a two-dimensional trans-abdominal ultrasound-based system (BAT System, NOMOS, Pennsylvania) [BAT] and a three-dimensional trans-abdominal ultrasound-based system (RESTITU System, Resonant Medical, Montreal) [RES]. A total of 217 BAT and 217 RES displacements measurements were collected within a minute of each other with all patients in the supine position. For prostate alignment with the BAT, two nearly orthogonal 2D ultrasound images obtained immediately prior to treatment were compared to the position of the CT-designed treatment planning volumes (i.e., cross-modality calculation method, comparing ultrasound to CT data). The RES system compared 3D ultrasound images acquired immediately prior to the planning CT scan to those acquired immediately prior to the treatment (i.e., intra-modality calculation method, comparing ultrasound to ultrasound data). Since the RES system resides in the CT-simulation room as well, prostate displacements were also compared to those measured by CT scan, which is the gold standard since it is used for treatment planning. This comparison was done in 10 patients, who were rescanned 3 additional times, at bi-weekly intervals, during their treatment course. The prostate displacement between the planning CT and the subsequent CT scans was calculated with the AcQSim CT-Sim Software (Phillips Medical Systems, Massachusetts) and compared to the 3D-US data obtained just prior each of the CT scans. Analysis performed on the difference in the paired 217 BAT and RES prostate displacements shows a mean difference of 0.9 (95% C.I. 0.5, 1.3) mm in the lateral [LAT] direction (p < 0.0001), of 0.1 (95% C.I. -0.5, 0.7) mm in the anteroposterior [A/P] direction (p = 0.604), and 6.0 (95% C.I. 5.4, 6.6) mm in the superoinferior [S/I] direction (p < 0.0001). These trends in the difference results are similar to those determined by Langen et. al.1, who compared the BAT system and implanted radio-opaque markers. Analysis of the thirty CT-scan and RES measured prostate displacements shows mean values of 0.2 (95% C.I. -0.4, 0.8) mm in the LAT direction (p = 0.314), - 0.3 (95% C.I. -0.9, 0.3) mm in the A/P direction (p = 0.405), and 0.1 (95% C.I. -0.5, 0.7) mm in the S/I directions (p = 0.727). Our study indicates that a significant systematic difference exists between cross-modality (BAT) and intra-modality (RES) methods when assessing prostate alignment during daily EBRT. Since RES displacements are consistent with the CT displacements, a more accurate prostate alignment is obtained when the RES method is used, compared to the BAT method.

Radiation therapy for rectosigmoid and rectal cancer: results of the 1992-1994 Patterns of Care process survey.

To determine the US national practice standards for patients with adenocarcinoma of the rectum treated in radiation oncology facilities. A national survey of 57 institutions identified 507 eligible patients who received radiation therapy as a component of their treatment for rectal cancer. A stratified two-stage cluster sampling with simple random sampling at each stage for each stratum was used and on-site surveys were performed. Of the 507 patients, 378 (75%) received postoperative therapy, 110 (22%) received preoperative therapy, 17 (2%) received both preoperative and postoperative therapy, and less than 0.5% received intraoperative radiation alone. To more accurately assess the utilization of modern radiation techniques as well as recommendations of the National Cancer Institute (NCI)-sponsored, randomized, postoperative, adjuvant combined modality therapy rectal cancer trials into current practice, the analysis was limited to the 243 (48%) patients with tumor, node, and metastasis staging system classification T3 and/or N1-2M0 disease who underwent conventional surgery with negative margins. Although only 7% were treated on a clinical trial, 90% received chemotherapy for a median of 21 weeks. Most were treated with modern radiation treatment techniques. In contrast, techniques to identify and help exclude the small bowel from the radiation field were not routinely used. Despite the fact that only 7% of patients with T3 and/or N1-2M0 disease were treated on a clinical trial, such trials appear to have resulted in a positive influence on the standard of practice within the oncology community. Although there are still some deficiencies, the majority of these patients received combined modality therapy and were treated with modern radiation therapy techniques.