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PURPOSE: to verify the possibility of using Helical Tomotherapy to safely escalate dose to single or multiple highly radioresistant dominant intra-prostatic lesions (DILs) as assessed by functional magnetic resonance imaging (MRI). MATERIAL: in seven intermediate/high risk patients, T2WI, T1WI and DWI MRI imaging showed evidence of one DIL in four patients and two DILs in three patients in the peripheral zone of the prostate. The planning strategy was to deliver median doses of 80, 90, 100 and 120 Gy to PTVDIL while delivering 71.4 Gy/28 fractions (EQD(2)=75 Gy) to the remaining portion of PTV. A higher priority was assigned to rectal constraints relative to DIL coverage. Rectal NTCP calculations were performed using the most recently available model data. RESULTS: the median dose to DIL could safely be escalated to at least 100 Gy (EQD(2,α/β=10)=113 Gy) without violating safe constraints for the organs at risk. Typical rectal NTCP values were around or below 1-3% for G3 toxicity and 5-7% for G2-G3 toxicity. For the 100 Gy DIL dose boost strategy, mean D95% of DIL and PTVDIL were 98.8 Gy and 86.7 Gy, respectively. The constraints for bladder, urethra and femoral heads were always respected. CONCLUSIONS: IGRT by Helical Tomotherapy may permit the safe escalation of EQD(2,α/β=10) to at least 113 Gy to DILs without significantly increasing rectal NTCP compared to plans without dose escalation. A Phase I-II clinical study is warranted

Aims and background: In the treatment of pancreatic carcinomas, one modality is intraoperative radiotherapy (IORT). A study was carried out to assess the feasibility of IORT alone or in a multimodality approach with postoperative adjuvant chemotherapy and external radiotherapy and to compare local control and survival of patients. Another objective of this retrospective study was to verify prognostic factors in resected patients treated with IORT. Methods: From January 1985 through September 1992, 54 adenocarcinomas of the pancreas (unresectable and resected patients) were treated with IORT by electron beam at the San Raffaele Hospital and then analyzed. Comparison was also carried out between IORT-treated resected patients and a non-randomized control group of resected patients treated without IORT in the same period. Results: In unresectable patients treated by laparotomy bypass and IORT, overall median survival was 6 months and 8 months in non-metastatic patients. Relief of severe pain present in 14 patients was observed in 85% within 12 days of IORT. As regards resected patients, the most important finding was that significantly better local control resulted from IORT. In fact, overall, local relapses were 25% in the IORT group and 55.8% in the non-IORT group (control group); instead, survival of the IORT group was not significantly longer than that of the control group. From a statistical analysis of resected patients treated with IORT and performed on prognostic factors on the basis of available data, survival was significantly influenced by tumor pathologic grading and diameter; postoperative adjuvant therapy was not a significant prognosis factor. Conclusions: IORT has a role in local control of unresectable pancreatic carcinomas and in control of resultant severe pain, In resected patients, IORT is effective in decreasing local recurrences but has little impact on survival. To obtain more satisfactory results, new and more effective adjuvant therapies and better abdominal prophylaxis should be tested.

PURPOSE: An adaptive concomitant boost (ACB) for the neo-adjuvant treatment of rectal cancer was clinically implemented. In this study population margins M(90,90) considering rectal deformation were derived for 10 consecutive patients treated at 18 × 2.3Gy with Helical Tomotherapy (HT) and prospectively validated on 20 additional patients treated with HT, delivering ACB in the last 6 fractions. METHODS: Sectorial margins M(90,90) of the whole and second treatment parts were assessed for 90% population through a method combining the 90% coverage probability maps of rectal positions (CPC90%) with 3D local distance measurements between the CPC90% and a reference rectal contour. M(90,90) were compared with the margins M(90,90)95%/99%, ensuring CPC90% coverage with 95%/99% confidence level. M(90,90) of the treatment second part were chosen as ACB margins which were clinically validated for each patient by means of %volume missing of CPC5/6 excluded by the ACB margins. RESULTS: The whole treatment M(90,90) ranged between 1.9 mm and 9 mm in the lower-posterior and upper-anterior sectors, respectively. Regarding ACB, M(90,90) were 7 mm in the anterior direction and

Background and purpose Gamma Knife Surgery (GKS) can be an adjunctive option to surgery in the case of pituitary adenomas. The effect of dosimetric variables on the incidence of new anterior pituitary deficits after GKS requires better definition. Materials and methods This retrospective study considered 130 patients with a follow up after GKS >6months. The diagnosis was nonfunctioning pituitary adenoma (NFPA) in 68 patients and secreting pituitary adenoma (SPA) in 62 patients. Median margin dose was 15/25Gy for NFPA and SPA, respectively. The endocrinological median follow-up was 60months. Hypopituitarism was defined as a new pituitary deficit in (at least) one of the three hormonal axes (hypogonadism, hypothyroidism and hypoadrenalism). The predictive value of clinical/dosimetric parameters was tested by univariate/multivariate analyses. Results Sixteen patients (12.3%) showed a new pituitary deficit in one or more axes. Multivariate analysis confirmed that the mean dose to the stalk/pituitary and the amount of healthy tissue within the high dose region were strong independent predictors of pituitary dysfunction; their best cut-off values were around 15.7Gy, 7.3Gy and 1.4cm 3 , respectively. Conclusions Our data showed a dose-dependent incidence of new hormonal deficits after GKS for pituitary adenoma. During planning definition, the risk of hypopituitarism could be reduced using the outlined safe dose–volume values.

Purpose To investigate the role of IMRT in reducing the risk of acute genito-urinary (GU), upper gastrointestinal (uGI) and lower gastrointestinal (lGI) toxicity following whole-pelvis irradiation (WPRT) after radical prostatectomy. Patients and methods 172 consecutive patients with prostate cancer were post-operatively irradiated to the prostatic bed (PB) and pelvic lymph-nodal area with adjuvant ( n =100) or salvage ( n =72) intent. Eighty-one patients underwent three-dimensional conformal (3DCRT) WPRT, while the remaining 91 underwent IMRT (54/91 with helical tomotherapy (HTT); 37/91 with Linac intensity-modulated RT (LinacIMRT)). Results Patients treated with IMRT experienced a decreased risk of acute toxicity. The crude incidence of grade ⩾2 toxicity was GU 12.3% vs. 6.6% ( p =0.19); lGI 8.6% vs. 3.2% ( p =0.14); uGI 22.2% vs. 6.6% ( p =0.004), for 3DCRT and IMRT, respectively. With respect to uGI and lGI, the acute toxicity profile of the HTT patients was even better when compared to that of 3DCRT patients (crude incidence:1.8% and 0.0%, respectively). Treatment interruptions due to uGI toxicity were 11/81 in the 3DCRT group vs. 2/91 in the IMRT group ( p =0.006). Conclusions The risk of acute toxicity following post-operative WPRT delivered by means of IMRT was reduced compared to that of 3DCRT. The most significant reduction concerned uGI, mainly owing to better bowel sparing with IMRT.

BACKGROUND AND PURPOSE:To assess the impact of using MRI and Helical Tomotherapy (HT) compared to 3DCRT and dynamic IMRT on the dose to the penile bulb (PB).MATERIALS AND METHODS:Eight patients diagnosed with prostate cancer entered a treatment protocol including CT and MRI simulation. The prostate apex was defined on both MRI and CT. Treatment plans (HT, Linac-IMRT, 3DCRT and conventional technique), were elaborated on both MRI and CT images. A dose of 71.4Gy (2.55Gy/fraction) was prescribed; it was requested that PTVs be covered by 95% isodose line. The mean dose and V50 of PB were evaluated.RESULTS:PTV-MRI plans reduced PB mean dose and V50 compared to PTV-CT plans. This improvement, deriving also from the treatment modality, was 89% for 3DCRT, 99% for Linac-IMRT and 97% for HT (p

Purpose: Characterizing the changes of PET-positive lymphnodes (PNs) of head-neck cancer patients during image-guided Tomotherapy in order to verify if our clinical margin for PTV boost are adequate. Material and methods: Weekly MVCTs of 30 patients were matched with the planning kVCT (kVCT_pl) on bony anatomy: 42 visible PNs were contoured on kVCT_pl/MVCTs. Intra/inter-observer and inter-modality variability in contouring PNs was evaluated by blind re-delineation. Shrinkage of PNs and center-of-mass (CM) shifts were measured and Van Herk margins for the residual error were estimated. In addition, due to the PNs' shrinkage during therapy, probability coverage maps were considered to estimate the fraction of the high probability contours missed by the clinical PTV (5mm margin); larger margins were tried for PNs showing some missing. Results: MVCTs were adequate for PNs' delineation (DICE=0.85; range=0.79–0.91). Twenty-seven PNs showed a significant volume shrinkage at the end of therapy (median: 71%, range: 27–94%, ρ =−0.93). Time–trend of 3D-CM shift was significant for 38% of PNs (median: 5.1mm at the end of treatment, range: 1.0–8.9). The clinical PTV included 95% of the 90%/100% probability contours in 40/36 (95%/86%) PNs respectively. Van Herk margins (not considering shrinkage) were approximately 7mm for all three main axes. The clinical PTV included 95% of the 90%/100% probability contours in 40/36 (95%/86%) PNs respectively. Conclusions: The residual error relative to PNs after bone match is relatively small; the impact of CM shifts is partially counterbalanced by shrinkage. Our results do not seem to support an extensive use of adaptive re-planning to avoid the missing of PNs in dose-escalated protocols, although more information about the dosimetry impact of the reported changes is warranted.

We investigated the possibility to early identify non-responding patients based on FDG-PET positive lymph nodes (PNs) volume variation assessed with in-room images.Twenty-seven head and neck cancer patients with at least one pre-treatment PNs were retrospectively analyzed; they received 54 Gy, 66 Gy, 69 Gy in 30 fractions on precautionary lymph nodal (N), primary (T) and PET positive (BTV) planning target volumes (PTVs), respectively with Helical TomoTherapy (SIB approach). PNs volume changes during treatment were assessed based on megavoltage computed tomography (MVCT) used for image guidance as ratio between volumes at fractions 10/20/30 and at first fraction. Data on T, N and M relapses (rT, rN, rM) were collected for all patients. The difference of PNs volume changes, during treatment, between patients with versus without relapses was tested (Mann-Whitney test). The impact of shrinkage on the corresponding survival curves (Cox proportional-hazard regression), dividing between no/moderate versus large shrinkage (based on ROC curve best cut-off value) was also investigated.Median follow-up was 27.4 m (3.7-108.9). The numbers for rT, rN, rM were 5, 4, 6, respectively. Differences in PNs shrinkage were found between patients with and without rT/rN at all considered timing [fr 20, rT: 0.56 vs. 1.07 (median), p = 0.06; rN: 0.57 vs. 1.25, p = 0.07]. Differences were lower for rM. Survival curves provide high hazard ratios (HR) between PNs changes and rT/rN at all considered timing [fr 20, rT: best cut-off = 0.58, HR 5.1 (95% CI 0.5-49.4), p = 0.12; rN: best cut-off = 0.98, HR 14.9 (1.6-142.9), p = 0.01].A limited shrinkage of PNs during treatment is associated with poorer outcome in terms of T/N relapses. The early variation of PNs observed on in-room images may provide useful information about the individual response with potential application in guiding an early adaptation of the treatment.

Images taken during and after RT for head and neck cancer have the potential to quantitatively assess xerostomia. Image information may be used as biomarkers of RT effects on parotid glands with significant potential to support adaptive treatment strategies. We investigated the possibility to extract information based on in-room CT images (kVCT, MVCT), acquired for daily image-guided radiotherapy treatment of head-and-neck cancer patients, in order to predict individual response in terms of toxicity. Follow-up MRI images were also used in order to investigate long term parotid gland deformation.

Purpose To compare helical Tomotherapy (HT), two volumetric-modulated arc techniques and conventional fixed-field intensity modulated techniques (S-IMRT) for head-neck (HN) cancers. Methods and materials Eighteen HN patients were considered. Four treatment plans were generated for each patient: HT, S-IMRT optimised with Eclipse treatment planning system and two volumetric techniques using Elekta–Oncentra approach (VMAT) and Varian-RapidArc (RA), using two full arcs. All techniques were optimised to simultaneously deliver 66Gy to PTV1 (GTV and enlarged nodes) and 54Gy to PTV2 (subclinical and electively treated nodes). Comparisons were assessed on several dosimetric parameters and, secondarily, on planned MUs and delivery time. Results Concerning PTV coverage, significantly better results were found for HT and RA. HT significantly improved the target coverage both compared to S-IMRT and VMAT. No significant differences were found between S-IMRT and volumetric techniques in terms of dose homogeneity. For OARs, all the techniques were able to satisfy all hard constraints; significantly better results were found for HT, especially in the intermediate dose range (15–30 Gy). S-IMRT reached a significantly better OARs sparing with respect to VMAT and RA. No significant differences were found for body mean dose, excepting higher values of V5–V10 for HT. A reduction of planned MUs and delivery treatment time was found with volumetric techniques. Conclusions The objectives of satisfying target coverage and sparing of critical structures were reached with all techniques. S-IMRT techniques were found more advantageous compared to RA and VMAT for OARs sparing. HT reached the best overall treatment plan quality.

Background and purpose: Comparing some isocentric coplanar techniques for conformal irradiation of prostate and seminal vesicles. Materials and methods: Five conformal techniques have been considered: (A) a 3-fields technique with an antero-posterior (AP) field and two lateral (LAT-LAT) 30 degrees wedged fields; (B) a 3-fields technique with an AP field and two oblique posterior (OBL) 15 degrees wedged fields with relative weights of 0.8, 1 and 1, respectively; (C) a 4-fields technique (AP-PA and LAT-LAT); (D) a 6-fields technique (LAT-LAT and four OBL at gantry angles 45 degrees, 135 degrees, 235 degrees and 315 degrees) with all the fields having the same weight; (E) the same 6-fields technique with lateral fields double-weighted with respect to the oblique fields. The conformal plans have been simulated on 12 consecutive patients (stages B and C) by using our 3D treatment planning system (Cadplan 2.7). The contours of the rectum, the bladder and the left femoral head were outlined together with the clinical target volume (CTV) which included the prostate and the seminal vesicles. A margin of 10 mm was added to define the planning target volume (PTV) through automatic volume expansion. Then a 7 mm margin between the PTV and block edges was added to take the beam penumbra into account. Dose distributions were normalised to the isocentre and the reference dose was considered to be 95% of the isocentre dose. Dose-volume histograms and dose statistics of the rectum, the bladder and the left femoral head were collected for all plans. For the rectum and the bladder the mean dose (Dm) and the fraction of volume receiving a dose higher than the reference dose (V95) were compared. For the femoral head, the mean dose together with the fraction of volume receiving a dose higher than 50% (V50) were compared. Results: Differences among the techniques have been found for all three considered organs at risk. When considering the rectum, technique A is better than the others both when considering Dm and V95 (P = 0.002), while technique D is the worst when considering Dm (P < 0.002) and is also worse than techniques A, E (P = 0.002) and C (P = 0.003) when considering V95. Technique E is the best when considering the bladder mean dose (P = 0.002 against A and D, P < 0.01 against B and C) and technique C is the worst (P < 0.012). No relevant differences were found for the bladder V95. in the femoral heads, techniques A and E are worse than B, C and D (P < 0.003) when considering Dm and V50. Moreover, techniques B and D are better than C (P < 0.004) when considering V50. Conclusions: There is no technique that is absolutely better than the others. Technique A gives the best sparing of the rectum; the bladder is better spared with technique E. These results are reached with a worse sparing of the femoral heads which should be carefully taken into account. (C) 1997 Elsevier Science Ireland Ltd.

The Jacobian of the deformation field of the registration between images taken during Radiotherapy is a measure of compression/expansion of the voxels within an organ. The Jacobian mean value was applied to investigate possible correlations between parotid deformation and anatomical, clinical and dosimetric parameters. Data of 84 patients were analyzed. Parotid deformation was evaluated through Jacobian maps of images taken at the start and at the end of the treatment. Several clinical, geometrical and dosimetric factors were considered. Correlation between Jacobian mean value and these parameters was assessed through Spearman’s test. Univariate and multivariate logistic analyses were performed by considering as the end point the first quartile value of the Jacobian mean value. Parotid dose volume histograms were stratified according to gland deformation, assessing the most predictive dose-volume combination. At multivariate analysis, age ( p = 0.02), overlap between tumor volume and parotid gland ( p = 0.0006) and the parotid volume receiving more than 10 Gy ( p = 0.02) were found as the best independent predictors, by considering Jacobian mean value fist quartile, the parotid volume receiving more than 10 Gy and 40 Gy were found as the most predictive dosimetric parameters. Parotid glands were divided in three different sub-groups (bad-, medium- and good dose volume histogram). The risk to have Jacobian means value lower than first quartile was 39.6% versus 19.6% versus 11.3% in these three groups. By including in the multivariate analysis this “dose volume grouping” parameter, age and bad dose volume histogram were found as the most predictive parameters for large shrinkage. The pattern of parotid deformation may be well predicted by some pre-treatment variables; a bad dose volume histogram seems the most important predictor.

Background and purpose Hypofractionated radiotherapy (RT) of pancreatic adenocarcinoma is limited by the tolerance of adjacent normal tissues. A better understanding of the influence of dosimetric variables on the rate of toxicity after RT must be considered an important goal. Methods and materials Sixty-one patients with histologically proven locally advanced disease (LAPD) were analyzed. The therapeutic strategy consisted of induction chemotherapy (ChT) followed by concurrent chemoradiotherapy (CRT). In 39 out of 61 patients the target volume was based on a four-dimensional CT (4D-CT) procedure. Delivered dose was 44.25Gy in 15 fractions to PTV 2 , which consisted of pancreatic tumor and regional lymph nodes considered radiologically involved; 23 out of 61 patients received a simultaneous integrated boost (SIB) to a tumor sub-volume infiltrating the great abdominal vessels (PTV 1 ) with dose in the range of 48–58Gy. RT was delivered with Helical Tomotherapy. Dose–volume histograms (DVHs) of target volumes and organs at risk (OARs) were collected for analysis. The predictive value of clinical/dosimetric parameters was tested by univariate/multivariate analyses. Results The crude incidence of acute gastrointestinal (GI) grade 2 toxicity was 33%. The 12-month actuarial rate of "anatomical" (gastro-duodenal mucosa damage) toxicity was 13% (95% CI: 4–22%). On univariate analysis, several stomach and duodenum DVH endpoints are predictive of toxicity after moderately hypofractionated radiotherapy. Multivariate analysis confirmed that baseline performance status and the stomach V 20 [%] were strong independent predictors of acute GI grade ⩾2 toxicity. The high-dose region of duodenum DVH ( V 45 [%]; V 40 [%]) was strongly correlated with grade ⩾2 "anatomical" toxicity; the best V 40 [%] and V 45 [%] cut-off values were 16% and 2.6% respectively. Conclusion Regarding dosimetric indices, stomach V 20 [%] correlates with a higher rate of acute toxicity; more severe acute and late anatomical toxicities are related to the high dose region of duodenum DVH.

PURPOSE: Measuring parotid density changes in patients treated with IMRT for head-neck cancer (HNC) and assessing correlation with treatment-related parameters. PATIENTS AND MATERIALS: Data of 84 patients treated with IMRT for different HNC were pooled from three institutions. Parotid deformation and average Hounsfield number changes (?HU) were evaluated through MVCT (with Helical Tomotherapy) or diagnostic kVCT images taken at the treatment start/end. Parotids were delineated in the first image and propagated to the last using a previously validated algorithm based on elastic registration. The correlation between ?HU and several treatment-related parameters was tested; then, logistic uni- and multi-variate analyses taking "large" ?HU as end-point were carried out. Due to the better image quality, analyses were repeated considering only kVCT data. RESULTS: ?HU was negative in 116/168 parotids (69%; for kVCT patients: 72/92, 78%). The average ?HU was significantly different from zero (-7.3, 0.20-0.25HU/fraction, p

Purpose To compare helical tomotherapy (HT) and intensity modulated proton therapy (IMPT) on early stage prostate cancer treatments delivered with simultaneous integrated boost (SIB) in moderate hypofractionation. Material/methods Eight patients treated with HT were replanned with two-field IMPT (2fIMPT) and five-field IMPT (5fIMPT), using a small pencil beam size (3 mm sigma). The prescribed dose was 74.3 Gy in 28 fractions on PTV1 (prostate) and PTV2 (proximal seminal vesicles), 65.5 Gy on PTV3 (distal seminal vesicles) and on the overlap between rectum and PTVs. Results IMPT and HT achieved similar target coverage and dose homogeneity, with 5fIMPT providing the best results. The conformity indexes of IMPT were significantly lower for PTV1+2 and PTV3. Above 65 Gy, HT and IMPT were equivalent in the rectum, while IMPT spared the bladder and the penile bulb from 0 to 70 Gy. From 0 up to 60 Gy, IMPT dosimetric values were (much) lower for all OARs except the femur heads, where HT was better than 2fIMPT in the 25–35 Gy dose range. OARs mean doses were typically reduced by 30–50% by IMPT. NTCPs for the rectum were within 1% between the two techniques, except when the endpoint was stool frequency, where IMPT showed a small (though statistically significant) benefit. Conclusions HT and IMPT produce similar dose distributions in the target volume. The current knowledge on dose–effect relations does not allow to quantify the clinical impact of the large sparing of IMPT at medium-to-low doses.

Purpose To assess anatomical, clinical and dosimetric pre-treatment parameters, possibly predictors of parotid shrinkage during radiotherapy of head and neck cancer (HNC). Materials Data of 174 parotids from four institutions were analysed; patients were treated with IMRT, with radical and adjuvant intent. Parotid shrinkage was evaluated by the volumetric difference (Δ V ) between parotid volumes at the end and those at the start of the therapy, as assessed by CT images (MVCT for 40 patients, KVCT for 47 patients). Correlation between Δ V cc/% and a number of dosimetric, clinical and geometrical parameters was assessed. Univariate as well as stepwise logistic multivariate (MVA) analyses were performed by considering as an end-point a Δ V cc/% larger than the median value. Linear models of Δ V (continuous variable) based on the most predictive variables found at the MVA were developed. Results Median Δ V cc/% were 6.95cc and 26%, respectively. The most predictive independent variables of Δ V cc at MVA were the initial parotid volume (IPV, OR: 1.100; p =0.0002) and D mean (OR: 1.059; p =0.038). The main independent predictors of Δ V % at MVA were age (OR: 0.968; p =0.041) and V 40 (OR: 1.0338; p =0.013). Δ V cc and Δ V % may be well described by the equations: Δ V cc=−2.44+0.076 D mean (Gy)+0.279 IPV (cc) and Δ V %=34.23+0.192 V 40 (%)−0.2203 age (year). The predictive power of the Δ V cc model is higher than that of the Δ V % model. Conclusions IPV/age and D mean/ V 40 are the major dosimetric and clinical/anatomic predictors of Δ V cc and Δ V %. Δ V cc and Δ V % may be well described by bi-linear models including the above-mentioned variables.

Purpose To find correlation between dose-volume histograms (DVHs) of the intestinal cavity (IC) and moderate-severe acute bowel toxicity in men with prostate cancer treated with pelvic nodal irradiation. Methods and Materials The study group consisted of 191 patients with localized prostate cancer who underwent whole-pelvis radiotherapy with radical or adjuvant/salvage intent during January 2004 to November 2007. Complete planning/clinical data were available in 175 of these men, 91 of whom were treated with a conventional four-field technique (50.4 Gy, 1.8 Gy/fraction) and 84 of whom were treated with IMRT using conventional Linac ( n = 26, 50.4 Gy, 1.8 Gy/fraction) or Helical TomoTherapy ( n = 58, 50–54 Gy, 1.8–2 Gy/fraction). The IC outside the planning target volume (PTV) was contoured and the DVH for the first 6 weeks of treatment was recovered in all patients. The correlation between a number of clinical and DVH (V10–V55) variables and toxicity was investigated in univariate and multivariate analyses. The correlation between DVHs for the IC outside the PTV and DVHs for the whole IC was also assessed. Results Twenty-two patients experienced toxicity (3/22 in the IMRT/tomotherapy group). Univariate analyses showed a significant correlation between V20–V50 and toxicity ( p = 0.0002–0.001), with a higher predictive value observed for V40–V50. Previous prostatectomy ( p = 0.066) and abdominal/pelvic surgery ( p = 0.12) also correlated with toxicity. Multivariate analysis that included V45, abdominal/pelvic surgery, and prostatectomy showed that the most predictive parameters were V45 ( p = 0.002) and abdominal/pelvic surgery ( p = 0.05, HR=2.4) Conclusions Our avoidance IMRT approach drastically reduces the incidence of acute bowel toxicity. V40–V50 of IC and, secondarily, previous abdominal/pelvic surgery were the main predictors of acute bowel toxicity.

To optimise image-guided radiotherapy (IGRT) approaches in set-up error correction for hypofractionated adjuvant treatment of prostate cancer using helical tomotherapy (HT).HT unit provides megavoltage - CT (MVCT) imaging capability for daily patient set-up. The intrinsic uncertainty of the available image registration techniques was first investigated on a pelvic phantom. To optimise different set-up correction strategies, MVCT data of 37 patients treated with 58 Gy delivered in 20 fractions were analyzed. 620 MVCT images were globally available for the analysis. Daily on-line set-up correction without any action level was applied for 27/37 patients. The residual and the effective set-up error were assessed. For 10/37 patients an off-line correction strategy with an action level was applied.Phantom measurements showed an intrinsic uncertainty in MVCT imaging and registration around 0.6 mm (+/-0.5 mm) for each of the three main axes. The minimum value of the residual systematic error was found at 7th-10th session, with values between 0.7 and 1.1 mm (1 SD); a systematic residual error2 mm for all directions was in any case found at 3rd-4th session. This result was also confirmed by the effective systematic set-up error analysis, with a minimum value within 1.5mm nearly at the 4th or 5th fraction.Although the minimum systematic residual error is reached at 7th-10th treatment session, the effective systematic set-up error analysis confirmed that an off-line correction at the 4th fraction without any action level may be a robust compromise with a large sparing of time and resources compared to on-line correction.

A procedure to improve target volume definition in pancreatic ductal adenocarcinoma by contrast enhanced 4D-CT imaging has been implemented for radiotherapy planning. The procedure allows good quality images to be obtained over the whole patient's breathing cycle in terms of anatomical details, pancreatic enhancement and vessel definition.

Background and Purpose To investigate the impact of Helical Tomotherapy (HT) upon the dose distribution when compared to our routinely delivered 3D conformal radiotherapy (CRT) in the case of patients affected by stage III non-small-cell lung cancer (NSCLC). Material and methods Thirteen stage III inoperable NSCLC patients were scheduled to receive 61.2–70.2 Gy, 1.8 Gy/fraction. Two treatment techniques (HT and CRT) were considered, and in the case of CRT the dose calculation was performed using both the pencil beam (PB) and Anisotropic Analytical Algorithm (AAA) available on the Varian Eclipse planning system. Dose volume constraints for PTV coverage and OAR sparing were assessed for the HT inverse planning with the highest priority upon PTV coverage and spinal cord sparing. The three plans were compared in terms of dose–volume histograms (DVHs) and normal tissue complication probability (NTCP). A statistical analysis was performed using non-parametric Wilcoxon matched pairs tests. Results In CRT the use of a less accurate algorithm (PB) decreased the monitor unit number by 2.4%. HT significantly improved dose homogeneity within PTV compared with CRT_AAA. For lung parenchyma V20–V40 were lower with HT, corresponding to a decrease of 7% in the risk of radiation pneumonitis. The volume of the heart and esophagus irradiated to >45–60 Gy were reduced using HT plans. For eight PTs with an esophagus–PTV overlap >5%, HT significantly reduced both late and acute esophageal complication probability. Conclusions Our findings obtained in stage III NSCLC patients underline that HT guarantees an important sparing of lungs and esophagus, thus HT has the potential to improve therapeutic ratio, when compared with CRT, by means of dose escalation and/or combined treatment strategy. In CRT of locally advanced lung cancers, the use of a more advanced algorithm would give significantly better modeling of target dose and coverage.

PURPOSE: To compare intensity-modulated proton therapy (IMPT) and helical tomotherapy (HT) treatment plans for nasopharynx cancer using a simultaneous integrated boost approach. METHODS AND MATERIALS: The data from 6 patients who had previously been treated with HT were used. A three-beam IMPT technique was optimized in the Hyperion treatment planning system, simulating a "beam scanning" technique. HT was planned using the tomotherapy treatment planning system. Both techniques were optimized to simultaneously deliver 66 Gy in 30 fractions to planning target volume (PTV1; GTV and enlarged nodes) and 54 Gy to PTV2 subclinical, electively treated nodes. Normal tissue complication probability calculation was performed for the parotids and larynx. RESULTS: Very similar PTVs coverage and homogeneity of the target dose distribution for IMPT and HT were found. The conformity index was significantly lower for protons than for photons (1.19 vs. 1.42, respectively). The mean dose to the ipsilateral and contralateral parotid glands decreased by 6.4 Gy and 5.6 Gy, respectively, with IMPT. The volume of mucosa and esophagus receiving > or =20 Gy and > or =30 Gy with IMPT was significantly lower than with HT. The average volume of larynx receiving > or =50 Gy was significantly lower with HT, while for thyroid, it was comparable. The volume receiving > or =30, > or =20, and > or =10 Gy in total body volume decreased with IMPT by 14.5%, 19.4%, and 23.1%, respectively. The normal tissue complication probability for the parotid glands was significantly lower with IMPT for all sets of parameters; however, we also estimated an almost full recovery of the contralateral parotid with HT. The normal tissue complication probability for the larynx was not significantly different between the two irradiation techniques. CONCLUSION: Excellent target coverage, homogeneity within the PTVs, and sparing of the organs at risk were reached with both modalities. IMPT allows for better sparing of most organs at risk at medium-to-low doses.