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

Purpose

Limited 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.

Optimization of box technique to reduce femur dose in radiation therapy of the pelvis.

Using the four field or “box technique” (opposing AP and lateral fields) in irradiating the pelvis, one can reduce the dose to the bladder and rectum while unavoidably irradiating the femurs. Four methods of applying the box technique with 4 MVP, ⁶⁰Co, and 24 MVP were analyzed to discover which technique delivers the lowest dose to the femurs: (1) Source-surface distance (SSD) equal given dose to all fields; (2) Source-axis distance (SAD) equal “air” dose to all fields; (3) SSD equal tumor dose to all fields; (4) SAD equal tumor dose to all fields. The results indicate that technique 1 (SSD equal given dose to all fields) gives the lowest dose to the femurs.     

Prediction of scattered dose to the testes in abdominopelvic radiotherapy

Radical abdominal radiotherapy in men runs the risk of impairing their fertility owing to scattered dose to the testes, outside of the treated volume. In patients for whom this is a concern it is important to be able to predict the dose to the testes before treatment in order to determine whether semen cryopreservation should be undertaken and testicular shielding performed during treatment. Measurements have been made on an anthropomorphic phantom to determine the magnitude of these doses for a four-field treatment consisting of an anterior-posterior parallel pair and a lateral parallel pair. A dataset is presented, which, together with a correction for patients size, allows an estimate of testicular dose to be made given only the photon energy, interfield distances and the distance from the testes to the nearest beam edge. Thermoluminescent dosimetry has been carried out in 17 patients to validate the use of the data tables. The results indicate that testicular doses may be estimated with a standard deviation corresponding to 1%-2% of the tumour dose, which is sufficient for the purpose of determining whether fertility is threatened by a planned treatment.     

A methodology for using SPECT to reduce intensity-modulated radiation therapy (IMRT) dose to functioning lung

PURPOSE: Single photon emission computed tomography (SPECT) provides a map of the spatial distribution of lung perfusion. Thus, SPECT guidance can be used to divert dose away from higher-functioning lung, potentially reducing lung toxicity. We present a methodology for achieving this aim and test it in intensity-modulated radiotherapy (IMRT) treatment-planning. METHODS AND MATERIALS: IMRT treatment plans were generated with and without SPECT guidance and compared for 5 patients. Healthy lung was segmented into four regions on the basis of SPECT intensity in the SPECT plan. Dose was sequentially allowed to the target via regions of increasing SPECT intensity. This process results in reduction of dose to functional lung, reflected in the dose-function histogram (DFH). The plans were compared using DFHs and F(20)/F(30) values (F(x) is the functional lung receiving dose above x Gy). RESULTS: In all cases, the SPECT-guided plan produced a more favorable DFH compared with the non-SPECT-guided plan. Additionally, the F(20) and F(30) values were reduced for all patients by an average of 13.6% +/- 5.2% and 10.5% +/- 5.8%, respectively. In all patients, DFHs of the two highest-functioning SPECT regions were reduced, whereas DFHs of the two lower-functioning regions were increased, illustrating the dose "give-take" between SPECT regions during redistribution. CONCLUSIONS: SPECT-guided IMRT shows potential for reducing the dose delivered to highly functional lung regions. This dose reduction could reduce the number of high-grade pneumonitis cases that develop after radiation treatment and improve patient quality of life.     

Response of the seminiferous epithelium to scattered radiation in seminoma patients

Semen and blood samples were obtained, at 3-month intervals over 12 to 28 months, from patients who underwent subdiaphragmal radiation after orchidectomy for seminoma testis. Before radiotherapy a mean (+/- SE) semen volume of 4.7 +/- 0.5 ml, a mean sperm count of 44.4 +/- 13.5 x 10(6)/ml, a mean percentage of motile cells of 20.3 +/- 5.2, a mean percentage of morphologically normal spermatozoa of 13.4 +/- 5.4, a mean percentage of swollen sperm of 39.6 +/- 7.4, and a mean serum follicle-stimulating hormone (FSH) value of 8.3 +/- 1.2 mIU/ml was found. The mean testicular dose from scatter was 62 +/- 5 cGy (range, 34 to 95 cGy). Sperm counts between 0 and 2.75 x 10(6)/ml were seen at 6.8 +/- 0.6 months and recovery to values greater than 2.25 x 10(6)/ml at 11.8 +/- 0.8 months after the start of radiation. Peak FSH values of 19.2 +/- 1.6 mIU/ml were obtained at 6.7 +/- 0.9 months after the start of irradiation. After recovery mean semen volume was 3.9 +/- 0.4 ml, mean sperm count 34.6 +/- 5.6 x 10(6)/ml, the mean percentage of motile cells 42.5 +/- 6.0, the mean percentage of swollen sperm 58.7 +/- 6.8, and the mean percentage of spermatozoa with normal morphology 23.4 +/- 5.1. Only motility was significantly different (P less than 0.01) from pretreatment values. The elevation of FSH values with time after start of radiotherapy reflected the toxicity to spermatogenesis but no correlation was found between peak FSH levels and scattered radiation dose. Also, neither the time from start of radiotherapy to sperm count nadir or recovery nor the time to peak FSH levels was significantly correlated with radiation dose.     

放疗中高次散射X线对剂量计算结果影响分析

目的 分析放疗中X线的高次散射对剂量计算结果的影响,解决将2次散射光子及高次散射光子对剂量贡献问题修正到1次散射光子散射剂量贡献中的可能性,为建立快速蒙特卡罗剂量计算方法提供支持。方法 采用X线与物质的作用截面理论和蒙特卡罗方法计算结果,分析1次、2次和高次散射X线对剂量计算精确度影响相对重要性。结果 ≥2次的高次散射对剂量的影响很小,并且可通过一小的修正系数被修正到1次散射X线的贡献中。结论 只追踪原射线和1次散射X线剂量贡献就可获得临床满意的剂量计算精确度,如用蒙特卡罗方法建立1次散射X线散射光子注量角分布和光子平均能量散射角分布模型数据库,将有助于提高临床剂量的蒙特卡罗计算效率。     

Tissue/dose compensation to reduce toxicity from combined radiation and chemotherapy for advanced head and neck cancers

SUMMARY This study was undertaken to quantify the reduction in normal tissue complications resulting from the aggressive management of advanced head and neck cancers (AHNCs) utilizing tissue/dose compensation (TDC). Thirty‐nine patients with AHNC were treated on an intensive chemotherapy + radiation regimen. Eighteen of 39 patients were treated using TDC; the remaining 21 patients were radiated without TDC (NTDC). Acute and chronic toxicities, swallowing, speech function, and quality of life were assessed. The TDC group had a smaller radiation dose gradient across the entire treatment volume. Unscheduled treatment breaks were required in 11% of TDC patients as compared with 43% of the NTDC group (P = 0.04). The TDC group had fewer Grade 3 or 4 acute and chronic toxicities and lower SOMA scores. At 3 months posttreatment, patients in the TDC group had better oral intake, lower pharyngeal residue, and better oropharyngeal swallowing efficiency and were able to swallow more bolus types. Patients in the TDC group also had better articulation. Use of TDC resulted in reduced treatment‐related interruptions, decreased acute and chronic toxicities, and better speech and swallowing functions. Techniques to improve radiation dose conformality around the target tissues while decreasing the radiation dose to the normal tissues should be an integral part of aggressive combined modality therapy. © 2002 Wiley‐Liss, Inc.     

Radiation exposure to patients from image guidance procedures and techniques to reduce the imaging dose

Purpose

To compare imaging doses from MV images, kV radiographs, and kV-CBCT and describe methods to reduce the dose to patient’s organs using existing on-board imaging devices.

Method and materials

Monte Carlo techniques were used to simulate kV X-ray sources. The kV image doses to a variety of patient anatomies were calculated by using the simulated realistic sources to deposit dose in patient CT images. For MV imaging, the doses for the same patients were calculated using a commercial treatment planning system.

Results

Portal imaging results in the largest dose to anatomic structures, followed by Varian OBI CBCT, Varian TrueBeam CBCT and then kV radiographs. The imaging doses for the 50% volume from the DVHs, D50, to the eyes for representative head images are 4.3–4.8 cGy; 0.05–0.06 cGy; 0.04–0.05 cGy; and, 0.12 cGy; D50 to the bladder for representative pelvis images are 3.3 cGy; 1.6 cGy; 1.0 cGy; and, 0.07 cGy; while D50 to the heart for representative thorax images are 3.5 cGy; 0.42 cGy; 0.2 cGy; and, 0.07 cGy; when using portal imaging, OBI kV-CBCT scans, TrueBeam kV-CBCT scans and kV radiographs, respectively. The orientation of the kV beam can affect organ dose. For example, D50 to the eyes can be reduced from 0.12 cGy using AP and right lateral radiographs to 0.008–0.017 cGy when using PA and right lateral radiographs. In addition, organ exposures can be further reduced to 15–70% of their original values with the use of a full-fan, bow-tie filter for kV radiographs. In contrast, organ doses increase by a factor of ∼2–4 if bow-tie filters are not used during kV-CBCT acquisitions.

Conclusion

Current on-board kV imaging devices result in much lower imaging doses compared to MV imagers even taking into account of higher bone dose from kV X-rays. And a variety of approaches are available to significantly reduce the image doses.     

Prostate displacement kit: reducing the radiation dose to the rectum.

During high dose-rate brachytherapy boost in 20 patients the use of a prostate-water-rectal-displacement-kit contributed to an increase in the distance between the prostate and the rectum, however, the prostate was not totally immobilized by the needles, implying the necessity for an very careful on-line dose-planning dosimetry.     

Reduction of the scatter dose to the testicle outside the radiation treatment fields

A technique is described to reduce the dose to the contralateral testicle of patients with testis tumors during retroperitoneal therapy with 10 MV X rays. When a conventional clam-shell shielding device was used, the dose to the testis from the photons scattered by the patient and the collimator jaws was found to be about 1.6% of the prescribed midplane dose. A more substantial gonadal shield made of low melting point Ostalloy, that reduced further the dose from internal scattered X rays, was therefore designed. A 10 cm thick lead scrotal block above the scrotum immediately outside the field is shown to reduce the external scattered radiation to negligible levels. Using the shield and the block, it is possible to reduce the dose to the testicle to one-tenth of one percent of the prescribed midplane dose.     

Low dose out-of-field radiotherapy,part 2: Calculating the mean photon energy values for the out-of-field photon energy spectrum from scattered radiation using Monte Carlo methods

Purpose

During radiotherapy, leakage from the machine head and collimator expose patients to out-of-field irradiation doses, which may cause secondary cancers. To quantify the risks of secondary cancers due to out-of-field doses, it is first necessary to measure these doses. Since most dosimeters are energy-dependent, it is essential to first determine the type of photon energy spectrum in the out-of-field area. The aim of this study was to determine the mean photon energy values for the out-of-field photon energy spectrum for a 6 MV photon beam using the GEANT 4–Monte Carlo method.

32P-Postlabeling assay for carcinogen--DNA adducts: description of beta shielding apparatus and semi-automatic spotting and washing devices that facilitate the handling of multiple samples

The utilization of the ³²P-postlabeling assay in combinationwith TLC for the sensitive detection and estimation of aromaticDNA adducts has been increasing in the past few years. The procedureconsists of ³²P-labeling of carcinogenadduded 3'-nucleotidesin the DNA digests using [-³²P]ATP and polynucleotide kinase,separation of ³²P-labeled adducts by TLC, and their detectiooby autoradiography. During both ³²P-labeling and initial phasesof TLC, a relatively high amount of [-³²P]ATP (3.0–4.5mCi) is handled when 30 samples are processed simultaneously.We describe the design of acrylic shielding apparatus, semi-automaticTLC spotting devices, and devices for development and washingof multiple TLC plates, which not only provide substantial protectionfrom exposure to ³²P beta radiation, but also allow quick andeasy handling of a large number of samples, thus expeditingthe assay workup and making it less laborintensive. Specifically,the equipment includes: (i) a multi-tube carousel rack (7.5cm diameter and 7.7 cm height) having 15 wells to hold caplessEppendorf tubes (0.5 ml) and a rotatable lid with an apertureto access individual tubes; (ii) a pipet shielder; (iii) twosemi-automatic spotting devices to apply radioactive solutionsto TLC plates; (iv) a multi-plate holder for TLC plates; and(v) a mechanical device for washing multiple TLC plates. Item(i) is small enough to be held in one-hand, vortexed, and centrifugedto mix the solutions in each tube while beta radiation is shielded.Items (iii) to (iv) aid in the automation of the assay.     

人外周血淋巴细胞微核分析用于估算离体模拟局部照射剂量的研究

目的：探讨利用人外周血淋巴细胞微核分析估算局部照射剂量的可行性。方法：收集2例人外周血样本,每例血样分为两部分,一部分不照射,另一部分再分成两组分别于1和5 Gy的⁶⁰Co γ射线下离体照射,剂量率为1 Gy/min。将来自同一样本的照射血与未照射血按1∶3或3∶1比例混合以模拟局部照射,共分析8组混合血样中双核淋巴细胞微核（MN）率,利用国际原子能机构（IAEA）推荐的Dolphin's模型推算混合血中受照血的微核率,并采用卫生行业标准（WS/T 178—1999）推荐的剂量效应曲线估算局部照射剂量。结果：各组混合血样MN分布均不符合泊松分布。1 Gy照射组估算的局部剂量与实际照射剂量偏差较大,5 Gy照射组估算的局部剂量与实际照射剂量较接近。结论：离体情况下,MN能较好的用于估算局部照射剂量,且MN可能更适用于较高剂量的估算。     

High radiation dose may reduce the negative effect of large gross tumor volume in patients with medically inoperable early-stage non-small cell lung cancer

PURPOSE: To determine whether the effect of radiation dose varies with gross tumor volume (GTV) in patients with stage I/II non-small cell lung cancer (NSCLC). METHODS AND MATERIALS: Included in the study were 114 consecutive patients with medically inoperable stage I/II NSCLC treated with three-dimensional conformal radiotherapy between 1992 and 2004. The median biologic equivalent dose (BED) was 79.2 Gy (range, 58.2-124.5 Gy). The median GTV was 51.8 cm(3) (range, 2.1-727.8 cm(3)). The primary endpoint was overall survival (OS). Kaplan-Meier estimation and Cox regression models were used for survival analyses. RESULTS: Multivariate analysis showed that there was a significant interaction between radiation dose and GTV (p < 0.001). In patients with BED < or = 79.2 Gy (n = 68), the OS medians for patients with GTV >51.8 cm(3) and < or = 51.8 cm(3) were 18.2 and 23.9 months, respectively (p = 0.015). If BED was >79.2 Gy (n = 46), no significant difference was found between GTV groups (p = 0.681). For patients with GTV >51.8 cm(3) (n = 45), the OS medians in those with BED >79.2 Gy and < or = 79.2 Gy were 30.4 and 18.2 months, respectively (p < 0.001). If GTV was < or = 51.8 cm(3) (n = 45), the difference was no longer significant (p = 0.577). CONCLUSION: High-dose radiation is more important for patients with larger tumors and may be effective in reducing the adverse outcome associated with large GTV. Further prospective studies are needed to confirm this finding.     

非小细胞肺癌自适应放疗剂量学研究

  目的  探索非小细胞肺癌实施自适应放疗后危及器官(肺、心脏、脊髓)受照剂量的变化, 及危及器官受照剂量降低后靶区处方剂量的变化。  方法  12例局部晚期非小细胞肺癌患者在放疗过程中均行两次定位CT扫描, 以实行自适应放疗。通过MIM软件, 将两次计划进行融合。比较实行自适应放疗后, 保证靶区剂量不变的情况下, 危及器官的受量有无降低; 以及在保证正常组织器官受照剂量与原计划相似的情况下靶区剂量提升的空间。  结果  自适应放疗后, 在保证靶区受照剂量不变的情况下, 肺部V20平均降低3.53%, V30降低2.55%, 而全肺平均受照剂量降低2.11 Gy; 心脏V30平均降低4.19%、V40降低3.72%;脊髓最大受量平均降低3.52 Gy。危及器官受量与不行自适应放疗时相似的情况下, 靶区(PGTV)照射剂量平均提高1.25 Gy。  结论  非小细胞肺癌放疗过程中, 适时行自适应放疗能够减少周围危及器官的受照剂量, 提高靶区(PGTV)的处方剂量。      

Reduction in radiation exposure to nursing personnel with the use of remote afterloading brachytherapy devices

The radiation exposure to nursing personnel from patients with brachytherapy implants on a large brachytherapy service were reviewed. Exposure to nurses, as determined by TLD monitors, indicates a 7-fold reduction in exposure after the implementation of the use of remote afterloading devices. Quarterly TLD monitor data for six quarters prior to the use of remote afterloading devices demonstrate an average projected annual dose equivalent to the nurses of 152 and 154 mrem (1.5 mSv). After the implementation of the remote afterloading devices, the quarterly TLD monitor data indicate an average dose equivalent per nurse of 23 and 19 mrem (0.2 mSv). This is an 87% reduction in exposure to nurses with the use of these devices (p less than 0.01).     

The use of a compensator library to reduce dose inhomogeneity in tangential radiotherapy of the breast.

BACKGROUND AND PURPOSE: The dose variation throughout the volume of the breast from tangential fields can exceed 20% for large breasts. This is postulated to result in poor cosmesis [Radiother Oncol 16 (1989) 253], particularly at the inframammary fold, where the dose is highest. Compensators may be used to reduce this variation, but at the cost of the time to manufacture each unique compensator for the individual patients. This paper outlines the implementation and routine use of a library of reusable compensators. MATERIALS AND METHODS: For the period of December 1999 to May 2001, 94 patients attending for breast radiotherapy received treatment using breast compensators calculated from multiple outlines measured using the Osiris system. The compensators manufactured for the early patients were added to a library for possible reuse by later patients. Of the 94 patients, 28 patients' compensators formed the library and 66 subsequent patients have been treated using compensators derived from the library. Selection of the most appropriate library compensator was determined from the analysis of the distribution of the calculated dose-volume histogram for the whole breast, excluding lung, penumbra and build-up regions. Once the library was complete, approximately 50% of all subsequent breast patients were treated with compensators (46% from the library and 4% with individual compensators). This represented a usage rate of 92% for the library compensators for those patients requiring compensation. RESULTS: In all cases the compensators reduced the variation in the dose distribution. For example, the group treated with a library compensator demonstrated a mean reduction from 29 to 9% for the volume of breast tissue receiving more than 5% greater than the reference dose. If the same patients had been treated using their own individual compensators, the corresponding value would have been 7%. There is a small systematic, but negligible, difference in the two populations of dose variation for individual versus library compensators, but this difference (P=0.20) did not reach the level of statistical significance of P=0.05). CONCLUSION: The method of creation and selection of library compensators has proved to be simple and reliable in practice. Every patient receiving radiotherapy for breast cancer is currently investigated under full software control to ascertain whether the use of a library compensator would be advantageous.