Utility of a skin marker-less setup procedure using surface-guided imaging: a comparison with the traditional laser-based setup in extremity irradiation.

This study aimed to assess the feasibility of a skin marker-less patient setup using a surface-guided radiotherapy (SGRT) system for extremity radiotherapy. Twenty-five patients who underwent radiotherapy to the extremities were included in this retrospective study. The first group consisted of 10 patients and underwent a traditional setup procedure using skin marks and lasers. The second group comprised 15 patients and had a skin marker-less setup procedure that used an SGRT system only. To compare the two setup procedures for setup accuracy, the mean 3D vector shift magnitude was 0.9 mm for the traditional setup procedure and 0.5 mm for the skin marker-less setup procedure (p < 0.01). In addition, SGRT systems have been suggested to improve the accuracy and reproducibility of patient setups and consistently reduce interfractional setup errors. These results indicate that a skin marker-less patient setup procedure using an SGRT system is useful for extremity irradiation.

A Japanese multi-institutional phase II study of moderate hypofractionated intensity-modulated radiotherapy with image-guided technique for prostate cancer.

BACKGROUND: The aim of this multi-institutional phase II study was to confirm the safety and the potential efficacy of moderately hypofractionated intensity-modulated radiotherapy (IMRT) with prostate-based image-guidance for Japanese patients. METHODS: Patients with low- or intermediate-risk localized prostate cancer were eligible. Patients with a part of high risk (having only one of the following factors, cT3a, 20 < PSA ≤ 30, or GS = 8 or 9) were also included. Hypofractionated IMRT using daily image-guided technique with prostate matching was performed with a total dose of 70 Gy in 28 fractions. Neoadjuvant hormonal therapy for 4-8 months was mandatory for patients with intermediate or high-risk prostate cancer. RESULTS: From 20 institutions, 134 patients enrolled. The median follow-up was 5.16 years (range, 1.43-6.47 years). The number of patients with low, intermediate, and high-risk prostate cancer was 20, 80, and 34, respectively. The 5-year overall, biochemical failure-free, and clinical failure-free survival was 94.5%, 96.0%, and 99.2%, respectively. The 5-year biochemical failure-free survival for patients with low-, intermediate-, and high-risk disease was 94.1%, 97.4%, and 93.9%, respectively. The incidences of grade 2 gastrointestinal (GI) and genitourinary (GU) late toxicities at 5 years were 5.3% and 5.3%, respectively. There are no acute or late toxicities ≥ grade 3. Of 124 patients who were followed for up to 5 years, the grade 2 late GU or GI toxicities were 10.5% (90% confidence intervals, 6.3-16.2%, p = 0.0958). CONCLUSION: The safety and efficacy of moderately hypofractionated IMRT with prostate-based image-guidance was confirmed among Japanese patients with prostate cancer.

Investigation of Halcyon multi-leaf collimator model in Eclipse treatment planning system: A focus on the VMAT dose calculation with the Acuros XB algorithm.

PURPOSE: The dual-layer multi-leaf collimator (MLC) in Halcyon involves further complexities in the dose calculation process, because the leaf-tip transmission varies according to the leaf trailing pattern. For the volumetric modulated arc therapy (VMAT) treatment, the prescribed dose for the target volume can be sensitive to the leaf-tip transmission change. This report evaluates the dosimetric consequence due to the uncertainty of the dual-layer MLC model in Eclipse through the dose verifications for clinical VMAT. Additionally, the Halcyon leaf-tip model is empirically adjusted for the VMAT dose calculation with the Acuros XB. MATERIALS AND METHODS: For this evaluation, an in-house program that analyzes the leaf position in each layer was developed. Thirty-two clinical VMAT plans were edited into three leaf sequences: dual layer (original), proximal single layer, or distal single layer. All leaf sequences were verified using Delta4 according to the dose difference (DD) and the global gamma index (GI). To improve the VMAT dose calculation accuracy, the dosimetric leaf gap (DLG) was adjusted to minimize the DD in single-layer leaf sequences. RESULTS: The mean of DD were -1.35%, -1.20%, and -1.34% in the dual-layer, proximal single-layer, and distal single-layer leaf sequences, respectively. The changes in the mean of DD between leaf sequences were within 0.2%. However, the calculated doses differed from the measured doses by approximately 1% in all leaf sequences. The tuned DLG was increased by 0.8 mm from the original DLG in Eclipse. When the tuned DLG was used in the dose calculation, the mean of DD neared 0% and GI with a criterion of 2%/2 mm yielded a pass rate of more than 98%. CONCLUSION: No significant change was confirmed in the dose calculation accuracy between the leaf sequences. Therefore, it is suggested that the dosimetric consequence due to the leaf trailing was negligibly small in clinical VMAT plans. The DLG tuning for Halcyon can be useful for reducing the dose calculation uncertainties in Eclipse VMAT and required in the commissioning for Acuros XB.

Gemcitabine plus nab-paclitaxel for locally advanced or borderline resectable pancreatic cancer.

Overall survival in a phase III study for metastatic pancreatic cancer has significantly improved with gemcitabine (GEM) plus nab-paclitaxel. However, to date, there is limited data on the efficacy and safety of its use for patients with locally advanced (LA) or borderline resectable pancreatic cancer (BRPC). Here, we investigated the efficacy and safety of first-line GEM plus nab-paclitaxel for LA or BRPC. We retrospectively analysed consecutive patients with pathologically confirmed, untreated LA or BRPC who started receiving first-line GEM plus nab-paclitaxel. A total of 30 patients (LA, n = 22; BRPC, n = 8) were analysed. Twelve patients (40%) without distant metastasis received additional chemoradiotherapy using S-1. Laparotomy was performed on 8 patients and 6 (20%; LA, n = 3; BR, n = 3) achieved R0 resection. Objective response rate was 44.8%. For all patients, median progression-free survival and overall survival were 14.8 and 29.9 months, respectively. Median overall survival for LA was 24.1 months with a 2-year survival rate of 50.8%. The most frequently observed grade 3 or 4 toxicities were neutropenia (73%) and biliary infection (13%). First-line GEM plus nab-paclitaxel was well-tolerated and feasible with an encouraging survival for LA or BRPC.

Effect of ICRU report 90 recommendations on Monte Carlo calculated kQ for ionization chambers listed in the Addendum to AAPM's TG-51 protocol.

PURPOSE: The ICRU has published new recommendations for ionizing radiation dosimetry. In this work, the effect of recommendations on the water-to-air and graphite-to-air restricted mass electronic stopping power ratios (sw, air and sg, air ) and the individual perturbation correction factors Pi was calculated. The effect on the beam quality conversion factors kQ for reference dosimetry of high-energy photon beams was estimated for all ionization chambers listed in the Addendum to AAPM's TG-51 protocol. METHODS: The sw, air , sg, air , individual Pi, and kQ were calculated using EGSnrc Monte Carlo code system and key data of both ICRU report 37 and ICRU report 90. First, the Pi and kQ were calculated using precise models of eight ionization chambers: NE2571 (Nuclear Enterprise), 30013, 31010, 31021 (PTW), Exradin A12, A12S, A1SL (Standard imaging), and FC-65P (IBA). In this simulation, the radiation sources were one 60 Co beam and ten photon beams with nominal energy between 4 MV and 25 MV. Then, the change in kQ for ionization chambers listed in the Addendum to AAPM's TG-51 protocol was calculated by changing the specification of the simple-model of ionization chamber. The simple-models were made with only cylindrical component modules. In this simulation, the radiation sources of 60 Co beam and 24 MV photon beam were used. RESULTS: The significant changes (p < 0.05) were observed for sw, air , sg, air , the wall correction factor Pwall , and the waterproofing sleeve correction factor Psleeve . The decrease in sw, air varied from -0.57% for a 60 Co beam to -0.36% for the highest beam quality. The decrease in sg, air varied from -0.72% to -1.12% in the same range. The changes in Pwall and Psleeve were up to 0.41% and 0.14% and those maximum changes were observed for the 60 Co beam. All changes in the central electrode correction factor Pcel , the stem correction factor Pstem , and the replacement correction factor Prepl were from -0.02% to 0.12%. Those changes were statistically insignificant (p = 0.07 or more) and were independent of photon energy. The change in kQ was mainly characterized by the change in sw, air , Pwall , and Psleeve . The relationship between the change in kQ and the beam quality index was linear approximately. The changes in kQ of the simple-models were agreed with those of the precise-models within 0.08%. CONCLUSION: The effects of ICRU-90 recommendations on kQ for the ionization chambers listed in the Addendum to AAPM's TG-51 protocol were from -0.15% to 0.30%. To remove the known systematic effect on the clinical reference dosimetry, the kQ based on ICRU-37 should be updated to the kQ based on ICRU-90.

Evaluation of gantry angle during respiratory-gated VMAT using triggered kilovoltage x-ray image.

Respiratory-gated volumetric modulated arc therapy (gated VMAT) involves further complexities to the dose delivery process because the gantry rotation must repeatedly stop and restart according to the gating signals. In previous studies, the gantry rotation performances were evaluated by the difference between the plan and the machine log. However, several reports pointed out that log analysis does not sufficiently replicate the machine performance. In this report, a measurement-based quality assurance of the relation between the gantry angle and gate-on or gate-off using triggered kilovoltage imaging and a cylinder phantom with 16 ball bearings is proposed. For the analysis, an in-house program that estimates and corrects the phantom offset was developed. The gantry angle in static and gated arc delivery was compared between the machine log and the proposed method. The gantry was set every 5 deg through its full motion range in static delivery, and rotated at three speeds (2, 4 and 6 deg s-1 ) with different gating intervals (1.5 or 3.0 s) in gated arc delivery. The mean and standard deviation of the angular differences between the log and the proposed method was -0.05 deg ± 0.12 deg in static delivery. The mean of the angular difference was within ±0.10 deg and the largest difference was 0.41 deg in gated arc delivery. The log records the output of the encoder so that miscalibration and mechanical sagging will be disregarded. However, the proposed method will help the users to detect the mechanical issues due to the repeated gantry stops and restarts in gated VMAT.

A multi-institutional observational study on the effects of three-dimensional radiotherapy and weekly 40-mg/m2 cisplatin on postoperative uterine cervical cancer patients with high-risk prognostic factors.

BACKGROUND: The aim of this study was to evaluate the effects of treatment with both three-dimensional radiotherapy (3DRT) and weekly 40-mg/m2 cisplatin on postoperative uterine cervical cancer patients with high-risk prognostic factors. METHODS: We conducted a retrospective multi-institutional chart review of postoperative uterine cervical cancer patients with high-risk prognostic factors who had been treated with both 3DRT and weekly 40-mg/m2 cisplatin from 2007 to 2012. Each participating hospital provided detailed information regarding patient characteristics, treatment outcomes, and treatment complications. RESULTS: The eligible 96 patients were analyzed. The median follow-up period was 61 months. The 3-year relapse-free survival, overall survival (OS), and locoregional relapse-free survival (LRFS) rates were 76%, 90%, and 88%, respectively. In multivariate analysis, the histological finding of either adenocarcinoma or adenosquamous carcinoma was a significant risk factor for both OS and LRFS. The percentage of patients with grade ≥ 3 acute hematologic toxicity, acute lower gastrointestinal toxicity (GIT), and late lower GIT were 45%, 19%, and 17%, respectively. CONCLUSIONS: The outcomes of concurrent chemoradiotherapy (CCRT) using weekly 40-mg/m2 cisplatin are similar to those in the previous studies that used several chemotherapy regimens. However, postoperative CCRT using 3DRT had a high level of late GIT.

Phase II study of induction gemcitabine and S-1 followed by chemoradiotherapy and systemic chemotherapy using S-1 for locally advanced pancreatic cancer.

PURPOSE: S-1 has systemic activity for locally advanced pancreatic cancer (LAPC). Here, the efficacy and safety of induction gemcitabine (GEM) and S-1 (GS) followed by chemoradiotherapy (CRT) and systemic chemotherapy using S-1 for LAPC were assessed. METHODS: The treatment consisted of four cycles of induction GS (S-1 60, 80, or 100 mg/day based on body surface area for 14 days every 3 weeks plus GEM 1000 mg/m2 on days 8 and 15), followed by S-1 (80, 100, or 120 mg/day based on body surface area on days 1-14 and 22-35) and concurrent radiotherapy (50.4 Gy in 28 fractions). Maintenance chemotherapy with S-1 was started 1-4 weeks after CRT until disease progression or unacceptable toxicity was observed. The primary endpoint was 1-year survival. RESULTS: A total of 30 patients with LAPC were enrolled. The median survival and progression-free survival were 21.3 and 12.7 months, respectively. Overall survival rates at 1, 2, 3, and 4 years were 73.3, 36.7, 23.3, and 16.7%, respectively. The median survival of 23 patients who received CRT was 22.9 months, with a 3-year survival rate of 30.4%. The two most common grade 3 or 4 adverse events during induction GS were neutropenia (63.3%) and biliary tract infection (20%). Toxicities during CRT or maintenance chemotherapy were generally mild. CONCLUSIONS: This regimen was feasible and highly active resulting in encouraging survival in patients with LAPC. Further investigations are warranted to elucidate the effectiveness of this treatment strategy in future studies. Clinical trials information: UMIN000006332.

Methionine Uptake and Required Radiation Dose to Control Glioblastoma.

PURPOSE: The purpose of this study was to retrospectively assess the feasibility of radiation therapy planning for glioblastoma multiforme (GBM) based on the use of methionine (MET) positron emission tomography (PET), and the correlation among MET uptake, radiation dose, and tumor control. METHODS AND MATERIALS: Twenty-two patients with GBM who underwent MET-PET prior to radiation therapy were enrolled. MET uptake in 30 regions of interest (ROIs) from 22 GBMs, biologically effective doses (BEDs) for the ROIs and their ratios (MET uptake:BED) were compared in terms of whether the ROIs were controlled for >12 months. RESULTS: MET uptake was significantly correlated with tumor control (odds ratio [OR], 10.0; P = .005); however, there was a higher level of correlation between MET uptake:BED ratio and tumor control (OR, 40.0; P < .0001). These data indicated that the required BEDs for controlling the ROIs could be predicted in terms of MET uptake; BED could be calculated as [34.0 × MET uptake] Gy from the optimal threshold of the MET uptake:BED ratio for tumor control. CONCLUSIONS: Target delineation based on MET-PET was demonstrated to be feasible for radiation therapy treatment planning. MET-PET could not only provide precise visualization of infiltrating tumor cells but also predict the required radiation doses to control target regions.

Therapeutic outcomes of neoadjuvant and concurrent androgen-deprivation therapy and intensity-modulated radiation therapy with gold marker implantation for intermediate-risk and high-risk prostate cancer.

OBJECTIVES: To investigate the therapeutic outcomes of neoadjuvant and concurrent androgen-deprivation therapy and intensity-modulated radiation therapy with gold marker implantation for intermediate- and high-risk prostate cancer. METHODS: This was a retrospective study of 325 patients with intermediate- or high-risk prostate cancer according to the National Comprehensive Cancer Network guidelines who underwent androgen-deprivation therapy and intensity-modulated radiation therapy (76 Gy) after gold marker implantation between 2001 and 2010. RESULTS: The 5-year distant metastasis-free survival rate was significantly lower for very high-risk patients than for intermediate- and high-risk patients (82.6% vs 99.4% and 96.5%, respectively; P < 0.01). The 5-year biochemical relapse-free survival rates significantly declined with increasing prostate cancer risk (P < 0.01), and were 95.9%, 87.2%, and 73.1% for the intermediate-risk, high-risk and very high-risk patients, respectively. Acute genitourinary and gastrointestinal toxicity grade ≥3 were not observed in any of the patients. Late grade 3 genitourinary toxicity occurred in 0.3% of patients. CONCLUSION: Combination androgen-deprivation therapy and 76-Gy intensity-modulated radiation therapy with gold marker implantation offers good therapeutic outcomes with few serious complications in patients with intermediate- and high-risk prostate cancer.

Phase 2 trial of hypofractionated high-dose intensity modulated radiation therapy with concurrent and adjuvant temozolomide for newly diagnosed glioblastoma.

PURPOSE/OBJECTIVES: To assess the effect and toxicity of hypofractionated high-dose intensity modulated radiation therapy (IMRT) with concurrent and adjuvant temozolomide (TMZ) in 46 patients with newly diagnosed glioblastoma multiforme (GBM). METHODS AND MATERIALS: All patients underwent postsurgical hypofractionated high-dose IMRT. Three layered planning target volumes (PTVs) were contoured. PTV1 was the surgical cavity and residual tumor on T1-weighted magnetic resonance images with 5-mm margins, PTV2 was the area with 15-mm margins surrounding the PTV1, and PTV3 was the high-intensity area on fluid-attenuated inversion recovery images. Irradiation was performed in 8 fractions at total doses of 68, 40, and 32 Gy for PTV1, PTV2, and PTV3, respectively. Concurrent TMZ was given at 75 mg/m(2)/day for 42 consecutive days. Adjuvant TMZ was given at 150 to 200 mg/m(2)/day for 5 days every 28 days. Overall and progression-free survivals were evaluated. RESULTS: No acute IMRT-related toxicity was observed. The dominant posttreatment failure pattern was dissemination. During a median follow-up time of 16.3 months (range, 4.3-80.8 months) for all patients and 23.7 months (range, 12.4-80.8 months) for living patients, the median overall survival was 20.0 months after treatment. Radiation necrosis was diagnosed in 20 patients and was observed not only in the high-dose field but also in the subventricular zone (SVZ). Necrosis in the SVZ was significantly correlated with prolonged survival (hazard ratio, 4.08; P=.007) but caused deterioration in the performance status of long-term survivors. CONCLUSIONS: Hypofractionated high-dose IMRT with concurrent and adjuvant TMZ altered the dominant failure pattern from localized to disseminated and prolonged the survival of patients with GBM. Necrosis in the SVZ was associated with better patient survival, but the benefit of radiation to this area remains controversial.

Stereotactic body radiotherapy (SBRT) for operable stage I non-small-cell lung cancer: can SBRT be comparable to surgery?

PURPOSE: To review treatment outcomes for stereotactic body radiotherapy (SBRT) in medically operable patients with Stage I non-small-cell lung cancer (NSCLC), using a Japanese multi-institutional database. PATIENTS AND METHODS: Between 1995 and 2004, a total of 87 patients with Stage I NSCLC (median age, 74 years; T1N0M0, n=65; T2N0M0, n=22) who were medically operable but refused surgery were treated using SBRT alone in 14 institutions. Stereotactic three-dimensional treatment was performed using noncoplanar dynamic arcs or multiple static ports. Total dose was 45-72.5 Gy at the isocenter, administered in 3-10 fractions. Median calculated biological effective dose was 116 Gy (range, 100-141 Gy). Data were collected and analyzed retrospectively. RESULTS: During follow-up (median, 55 months), cumulative local control rates for T1 and T2 tumors at 5 years after SBRT were 92% and 73%, respectively. Pulmonary complications above Grade 2 arose in 1 patient (1.1%). Five-year overall survival rates for Stage IA and IB subgroups were 72% and 62%, respectively. One patient who developed local recurrences safely underwent salvage surgery. CONCLUSION: Stereotactic body radiotherapy is safe and promising as a radical treatment for operable Stage I NSCLC. The survival rate for SBRT is potentially comparable to that for surgery.

Stereotactic body radiotherapy for lung tumors at the pulmonary hilum.

BACKGROUND AND PURPOSE: High-dose irradiation to the pulmonary hilar region is generally considered to be of high risk in causing bronchial injury. The aim of this retrospective study is to investigate the safety and efficacy of stereotactic body radiotherapy (SBRT) for patients with lung tumors in the pulmonary hilum. PATIENTS AND METHODS: 21 patients who underwent SBRT for lung tumors within 2 cm from a major bronchus were retrospectively analyzed. The total biologically effective doses ranging from 50.7 to 157.5 Gy (median, 100 Gy) were given to the tumors by SBRT. RESULTS: The overall survival rates at 1 and 2 years after SBRT were 90.0% and 62.2%, respectively. Nine patients were alive and 15 irradiated tumors were controlled during the follow-up period of 10-54 months (median, 20 months). Nine patients died of tumor progression and one patient each died of hemoptysis, infectious pneumonia, and epidural hemorrhage. Severe late toxicity (>or= grade 3) was seen in three patients of whom two had previously received repeated radiotherapy. CONCLUSION: SBRT for lung tumors located in the pulmonary hilar region may be tolerable and acceptable, if multiple treatments to the same major bronchus are avoided, and irradiated volumes are carefully taken into consideration.

Compensatory enlargement of the liver after treatment of hepatocellular carcinoma with carbon ion radiotherapy - relation to prognosis and liver function.

BACKGROUND AND PURPOSE: To examine whether liver volume changes affect prognosis and hepatic function in patients treated with carbon ion radiotherapy (CIRT) for hepatocellular carcinoma (HCC). MATERIAL AND METHODS: Between April 1995 and March 2003, among the cases treated with CIRT, 43 patients with HCC limited to the right hepatic lobe were considered eligible for the study. The left lateral segment was defined as the non-irradiated region. Liver volume was measured using contrast CT at 0, 3, 6, and 12 months after CIRT. We examined serum albumin, prothrombin activity, and total bilirubin level as hepatic functional reserve. RESULTS: After CIRT, the non-irradiated region showed significant enlargement, and enlarged volume of this region 3 months after CIRT 50 cm(3) was a prognostic factor. The 5-year overall survival rates were 48.9% in the larger enlargement group (enlarged volume of non-irradiated region 3 months after CIRT > or =50 cm(3)) and 29.4% in the smaller enlargement group (as above, <50 cm(3)). The larger enlargement group showed better hepatic functional reserve than the smaller enlargement group 12 months after CIRT. CONCLUSIONS: This study suggests that compensatory enlargement in the non-irradiated liver after CIRT contributes to the improvement of prognosis.

Comparison of respiratory-gated and respiratory-ungated planning in scattered carbon ion beam treatment of the pancreas using four-dimensional computed tomography.

PURPOSE: We compared respiratory-gated and respiratory-ungated treatment strategies using four-dimensional (4D) scattered carbon ion beam distribution in pancreatic 4D computed tomography (CT) datasets. METHODS AND MATERIALS: Seven inpatients with pancreatic tumors underwent 4DCT scanning under free-breathing conditions using a rapidly rotating cone-beam CT, which was integrated with a 256-slice detector, in cine mode. Two types of bolus for gated and ungated treatment were designed to cover the planning target volume (PTV) using 4DCT datasets in a 30% duty cycle around exhalation and a single respiratory cycle, respectively. Carbon ion beam distribution for each strategy was calculated as a function of respiratory phase by applying the compensating bolus to 4DCT at the respective phases. Smearing was not applied to the bolus, but consideration was given to drill diameter. The accumulated dose distributions were calculated by applying deformable registration and calculating the dose-volume histogram. RESULTS: Doses to normal tissues in gated treatment were minimized mainly on the inferior aspect, which thereby minimized excessive doses to normal tissues. Over 95% of the dose, however, was delivered to the clinical target volume at all phases for both treatment strategies. Maximum doses to the duodenum and pancreas averaged across all patients were 43.1/43.1 GyE (ungated/gated) and 43.2/43.2 GyE (ungated/gated), respectively. CONCLUSIONS: Although gated treatment minimized excessive dosing to normal tissue, the difference between treatment strategies was small. Respiratory gating may not always be required in pancreatic treatment as long as dose distribution is assessed. Any application of our results to clinical use should be undertaken only after discussion with oncologists, particularly with regard to radiotherapy combined with chemotherapy.

Impact of intrafractional bowel gas movement on carbon ion beam dose distribution in pancreatic radiotherapy.

PURPOSE: To assess carbon ion beam dose variation due to bowel gas movement in pancreatic radiotherapy. METHODS AND MATERIALS: Ten pancreatic cancer inpatients were subject to diagnostic contrast-enhanced dynamic helical CT examination under breath-holding conditions, which included multiple-phase dynamic CT with arterial, venous, and delayed phases. The arterial-venous phase and arterial-delayed phase intervals were 35 and 145 s, respectively. A compensating bolus was designed to cover the target obtained at the arterial phase. Carbon ion dose distribution was calculated by applying the bolus to the CT data sets at the other two phases. RESULTS: Dose conformation to the clinical target volume was degraded by beam overshoot/undershoot due to bowel gas movement. The D95 for clinical target volume was degraded from 98.2% (range, 98.0-99.1%) of the prescribed dose to 94.7% (range, 88.0-99.0%) at 145 s. Excessive dosing to normal tissues varied among tissues and was, for example, 12.2 GyE/13.1 GyE (0 s/145 s) for the cord and 38.8 GyE/39.8 GyE (0 s/145 s) for the duodenum. The magnitude of beam overshoot/undershoot was particularly exacerbated from the anterior and left directions. CONCLUSIONS: Bowel gas movement causes dosimetric variation to the target during treatment for radiotherapy. The effect of bowel gas movement varies with beam angle, with greatest influence on the anterior-posterior and left-right beams.

Four-dimensional measurement of intrafractional respiratory motion of pancreatic tumors using a 256 multi-slice CT scanner.

PURPOSE: To quantify pancreas and pancreatic tumor movement due to respiratory motion using volumetric cine CT images. MATERIALS AND METHODS: Six patients with pancreatic tumors were scanned in cine mode with a 256 multi-slice CT scanner under free breathing conditions. Gross tumor volume (GTV) and pancreas were manually contoured on the CT data set by a radiation oncologist. Intrafractional respiratory movement of the GTV and pancreas was calculated, and the results were compared between the respiratory ungated and gated phases, which is a 30% duty cycle around exhalation. RESULTS: Respiratory-induced organ motion was observed mainly in the anterior abdominal side than the posterior side. Average GTV displacement (ungated/gated phases) was 0.7 mm/0.2mm in both the left and right directions, and 2.5mm/0.9 mm in the anterior, 0.1 mm/0mm in the posterior, and 8.9 mm/2.6mm in the inferior directions. Average pancreas center of mass displacement relative to that at peak exhalation was mainly in the inferior direction, at 9.6mm in the ungated phase and 2.3mm in the gated phase. CONCLUSIONS: By allowing accurate determination of the margin, quantitative analysis of tumor and pancreas displacement provides useful information in treatment planning in all radiation approaches for pancreatic tumors.

Long-term control of disseminated pleomorphic xanthoastrocytoma with anaplastic features by means of stereotactic irradiation.

Pleomorphic xanthoastrocytoma (PXA) is a rare astrocytic neoplasm of the brain. Some PXAs are accompanied by anaplastic features and are difficult to manage because of frequent recurrences that lead to early death. No previous reports have demonstrated consistent efficacy of adjuvant radiotherapy or chemotherapy for this disease. We report a case of PXA with anaplastic features treated with stereotactic irradiation (STI) that resulted in long-term control of repeatedly recurring nodules throughout the neuraxis. A 47-year-old woman presented with an epileptic seizure due to a large tumor in the right frontal lobe. The tumor was resected and diagnosed as PXA with anaplastic features. Sixteen months later, a relapse at the primary site was noted and treated with stereotactic radiosurgery using Gamma Knife. Two years later, the patient developed a tumor nodule in the cervical spinal cord that histologically corresponded to a small-cell glioma with high cellularity and prominent MIB-1 (mindbomb homolog 1) labeling. In the following months, multiple nodular lesions appeared throughout the CNS, and STI was performed six times for eight intracranial lesions using Gamma Knife and twice using a linear accelerator, for three spinal cord lesions in total. All lesions treated with STI were well controlled, and the patient was free from symptomatic progression for 50 months. However, diffuse dissemination along the craniospinal axis eventually progressed, and she died 66 months after initial diagnosis. Autopsy showed that the nodules remained well demarcated from the surrounding nervous system tissue. STI may be an effective therapeutic tool for controlling nodular dissemination of PXA with anaplastic features.

Water-equivalent pathlength reproducibility due to respiratory pattern variation in charged-particle pancreatic radiotherapy.

We evaluated the water-equivalent length (WEL) reproducibility due to variation in the external respiratory marker position when using a 4DCT scan in respiratory-gated charged-particle treatment. Two sets of pancreatic 4DCT data from two patients were acquired under free breathing conditions with 256-slice CT. The 4DCT data included two exhalation phases and the respiratory patterns in each patient differed, one being regular and the other irregular. The WEL calculation region is defined in the first respiratory cycle by two planes, one at the patient entrance surface and the other behind the target in the anterior-posterior (AP) and posterior-anterior (PA) directions. In the regular respiratory pattern, the WEL variation within the target region was less than 1.7 mm between the first and second exhalations in both AP and PA calculation directions. However, in the irregular breathing pattern, the respiratory amplitude at the second exhalation was 20% lower than that at the first exhalation; therefore, WEL variations from 8.1 to -9.1 mm and from 3.1 to -3.4 mm were observed within the target region in the AP and PA calculation directions, respectively. The WEL variation in the PA direction was smaller than that in the AP direction because the abdominal thickness is affected more in the AP direction. Respiratory pattern variation even affects WEL values in the respiratory-gated phase. This variation should be considered in treatment planning, and necessary improvements in respiratory reproducibility should be made.

11C-methionine-PET for evaluation of carbon ion radiotherapy in patients with pelvic recurrence of rectal cancer.

PURPOSE: Progress of the novel carbon ion radiotherapy (CIRT) in the treatment of cancers has created the need for a method to accurately evaluate the response. We investigated whether L-[11C]methyl-methionine (11C-methionine) uptake at pre- and post-CIRT could be an early response predictor in patients with pelvic recurrence of rectal cancer. PROCEDURES: 11C-Methionine-positron emission tomography (PET) was performed prospectively in 53 patients with pelvic recurrence of rectal cancer before CIRT, and 48 patients were performed 11C-methionine PET at 1 month after CIRT. 11C-Methionine tumor uptake was measured by the tumor to muscle ratio (T/M ratio). The T/M ratios were evaluated in relation to clinical outcomes such as local re-recurrence, distant metastasis, and survival. The response to CIRT was also judged by computed tomography (CT) and magnetic resonance imaging (MRI). 11C-Methionine PET judgment was compared with CT/MRI judgment regarding the relevance to clinical outcome. RESULTS: Baseline T/M ratio was 5.27+/-1.90 (mean+/-SD) in patients without developing local re-recurrence and 7.66+/-3.17 in patients with local re-recurrence (p=0.023, Mann-Whitney U test). Post-CIRT T/M ratios were 3.10+/-1.28 in patients without local re-recurrence and 6.15+/-2.98 in patients with local re-recurrence (p=0.006, Mann-Whitney U test). By Kaplan-Meier analysis with log-rank test, patients with a baseline T/M ratio of