Koilpillai Joseph Maria Das

Variations of intracavitary applicator geometry during multiple HDR brachytherapy insertions in carcinoma cervix and its influence on reporting as per ICRU report 38

PURPOSE This paper examines the extent of variation in the applicator geometry during multiple high dose rate (HDR) intracavitary brachytherapy (ICBT) applications and its impact on reporting as per ICRU report 38. MATERIALS AND METHODS Eighty orthogonal radiographs from 20 consecutive patients of carcinoma cervix (FIGO stages, IIA-IIIB) having four HDR ICBT applications of 6 Gy each at weekly intervals following teletherapy were evaluated. The applicator consisted of a flexible intrauterine tandem (IUT) independent of the ovoid assembly. The applicator geometry was evaluated in terms of: alpha angle, beta angle, intrauterine length (IUTL), interovoid (IOV), os to right ovoid (ORT) and os to left ovoid (OLT) distances along with vertical (VDL) and anteroposterior displacements (ADL) of the os with respect to the ovoids. The Cartesian co-ordinates (X, Y, and Z) of the IUT tip, centre of both ovoids and os were also measured. Doses to right point A (ARD), left point A (ALD), along with a reference volume of 6 Gy for ICRU height (IRH), width (IRW), thickness (IRT) and volume (IRV) were estimated for each application. RESULTS Highly significant differences (P<0.001) between four insertions in any given patient across 20 patients for alpha angle, beta angle, IUTL, IOV, ORT, VDL, co-ordinates of the IUT, ovoids and os were observed, except for ADL (P=0.041) and OLT (P=0.247). As a consequence, variations were observed in ARD (P=0.027), ALD (P=0.017); IRH, IRW, IRT and IRV (all P<0.001). Applicator factors which influenced the various dose specification parameters were: beta angle and ORT for both ARD and ALD; UTLN, VDL and ORT for IRH; UTLN and IOV for IRW; UTLN for IRT and VDL for the 6 Gy IRV. CONCLUSIONS A significant variation of the applicator geometry and its movement was observed in patients undergoing multiple HDR ICBT. This could have implications for reporting dose and volume specifications as required by ICRU report 38.

Serial diffusion tensor imaging to characterize radiation-induced changes in normal-appearing white matter following radiotherapy in patients with adult low-grade gliomas

PurposeThe aim of this study was to ascertain whether diffusion tensor imaging (DTI) metrics—fractional anisotropy (FA), mean diffusivity (MD), linear case (CL), planar case (CP), spherical case (CS)—can characterize a threshold dose and temporal evolution of changes in normal-appearing white matter (NAWM) of adults with low-grade gliomas (LGGs) treated with radiation therapy (RT).Methods and materialsConventional and DTI imaging were performed before RT in 5 patients and subsequently, on average, at 3 months (n = 5), 8 months (n = 3), and 14 months (n = 5) following RT for a total of 18 examinations. Isodose distribution at 5-Gy intervals were visualized in all the slices of fluid attenuated inversion recovery (FLAIR) and the corresponding DTI images without diffusion sensitization (b0DTI). The latter were exported for relative quantitative analysis.ResultsCompared to pre-RT values, FA and CL decreased, whereas CS increased at 3 and 8 months and recovered partially at 14 months for the dose bins > 55 Gy and 50–55 Gy. For the 45–50 Gy bin, the FA and CL decreased with an increase in CS at 3 months; no further change was seen at 8 or 14 months. For the >55 Gy and 50–55 Gy bins, CP decreased and MD increased at 3 months and returned to baseline at 8 months following RT.ConclusionRadiation-induced changes in NAWM can be detected at 3 months after RT, with changes in FA, CL, and CS (but not CP or MD) values seen at a thresh-old dose of 45–50 Gy. A partial recovery was evident by 14 months to regions that received doses of 50–55 Gy and >55 Gy, thus providing an objective measure of radiation effect on NAWM.

Problems in reporting doses and volumes during multiple high-dose-rate intracavitary brachytherapy for carcinoma cervix as per ICRU Report 38: a comparative study using flexible and rigid applicators

OBJECTIVE The objective was to evaluate the extent of geometric and positional variations of two different applicators during multiple high-dose-rate (HDR) intracavitary brachytherapy (ICBT) in carcinoma cervix and its implication on reporting as per International Commission on Radiation Units and Measurement (ICRU) Report 38. METHODS Fifty patients, following teletherapy, were randomly allocated to two groups of 25 each. They received a dose of 6 Gy to point A during each of the three HDR ICBT applications by either a flexible Ralstron or a rigid geometry Rotterdam applicator. The various applicator components related to its geometry and their Cartesian coordinates were evaluated from orthogonal films. The doses to ICRU bladder, rectal, pelvic, lymphatic trapezoid points, and dimensions of 6-Gy ICRU height, width, thickness, and volume were estimated for each application. RESULTS Significant variation was observed with the three HDR ICBT applications for each group, for all components and for both applicators, although it was relatively more with the flexible Ralstron applicator. The average shift in each of the coordinates of os, uterine tip, and ovoids was around 10 mm for both groups. These resulted in significant variations in all the ICRU Report 38 reporting parameters for three insertions in any given patient and across 25 patients of both groups. CONCLUSIONS Multiple HDR ICBT applications led to significant variation in the applicator geometry and its positions in pelvis, irrespective of the applicator rigidity. This results in uncertainties in reporting as per ICRU Report 38 guidelines, and thus calls for its revision.

Total reference air kerma: To what extent can it predict intracavitary volume enclosed by isodose surfaces during multiple high-dose rate brachytherapy?

BACKGROUND The International Commission on Radiation Units and Measurements (ICRU) report 38 recommends reporting of total reference air kerma (TRAK) and reference ICRU isodose volumes during intracavitary brachytherapy (ICBT) in cancer of the cervix. The present study attempts to estimate the volumes enclosed by isodose surfaces from TRAK and evaluate its utility to represent doses to organs of interest. MATERIAL AND METHODS Volumes encompassed by isodose surfaces of 3 Gy, 6 Gy, 9 Gy, and 12 Gy were obtained for 90 high-dose rate (HDR) ICBT procedures. These were used to derive a relation between isodose volumes, TRAK/dose (K/D), and rectal and bladder doses. RESULTS Actual volumes (V) encompassed by isodose surfaces were reflected as a quadratic function of K/D (r(2)=0.998) and the expression, V=-23.09+1295.99(K/D)+5661.65(K/D)(2) gave the best estimates for various volumes. No correlation was observed between TRAK and bladder (r(2)=0.086) or rectal doses (r(2)=0.082). CONCLUSIONS Estimates of volumes encompassed by different dose levels from TRAK could be derived with reasonable certainty. However, TRAK fails to correlate with rectal and bladder doses.

Safety and Efficacy of Concurrent Cisplatin and Radiotherapy in Inoperable or Metastatic Squamous Cell Esophageal Cancer

Between August 1996 and May 1999, 50 consecutive, previously untreated patients with carcinoma of the esophagus and who were inoperable for various reasons were treated with weekly doses of cisplatin (35 mg/m 2 , maximum 7 cycles) concurrent with either 66 Gy/33 fractions external beam radiotherapy (EBRT) (n=42) or 50 Gy/25 fractions EBRT and two insertions of high-dose-rate intraluminal radiotherapy of 6 Gy each, spaced a week apart (n=8). Eighty-two percent (41/50) of the patients received the stipulated radiotherapy (RT) dose. Seventy-six percent (38/50) received at least 6 cycles of chemotherapy. Neutropenia in the form of WHO grade II-12% (6/50) and grade III-2% (1/50) was observed. Grade III emesis was seen in 8% (4/50). Improvement in the swallowing status was seen in 84% (42/50). Median duration of dysphagia relief was 6 months. The median overall survival was 9 months with 17% estimated to be alive after 4 years. Combined treatment with single agent cisplatin and definitive radiotherapy for inoperable cancer of the esophagus is safe, well tolerated and reasonably efficacious.

Role of videofluorography in assessing functional abnormalities in patients of head and neck cancer treated with chemoradiotherapy

Aim:  The major toxicity following treatment for head neck cancer is swallowing dysfunction which can be easily assessed by videofluorography (VFG), allowing documentation of the site and extent of abnormality thereby facilitating directed management.

Is aspiration as detected on pretreatment video fluorography, a harbinger of poor quality of life and early mortality in cancers of the upper aerodigestive tract treated with radiotherapy?

Background: Patients with cancers of the upper aerodigestive tract (head and neck cancer (HNC)) tend to aspirate, either due to disease or treatment. The association of aspiration (documented on video fluorography (VFG)) with quality of life (QOL) and unexpected mortality was studied prospectively in patients treated with simultaneous integrated boost technique of intensity-modulated radiotherapy (SIB-IMRT). Materials and Methods: Moderately advanced (stage III/IV) HNC were treated by SIB-IMRT delivering 66 Gy/30 fr, 60 Gy/30 fr, and 54 Gy/30 fr to high, intermediate, and low risk volumes, respectively. They underwent serial VFG and QOL assessments (Quality of Life Questionnaire-Core 30 (QLQ-C30) and head and neck-35 (HN35) European Organisation for Research and Treatment of Cancer (EORTC) tools) at 0, 3, and 6 months. Pharyngeal musculature (PM) was additionally delineated on planning computed tomography (CT) scans as potential organs at risk (OARs). Results: Between November 2009 and May 2011, 20 HNC were treated as per protocol. All patients were fit (Karnofsky performance status (KPS) ≥ 80). Based on VFG findings, seven patients (4/9 oropharynx and 3/11 laryngopharynx) were grouped as aspirators (A) and remaining 13 as non-aspirators (NA). The QOL study showed that pretreatment coughing and swallowing difficulties were greater in group A versus NA and remained persistently higher. In group A, deaths attributable to aspiration were seen in 3/7 patients, while none occurred in the NA group (Fishers exact P = 0.03). The mean PM dose was 60 Gy in both the groups and mean V60 was similar at 69 and 67% in A and NA groups, respectively. Conclusions: VFG helps identify patients who aspirate and are at risk of premature death due to its complications, alerting caregivers to direct attention appropriately.

Biological integral dose: an alternate method for numerical scoring of rival plans.

Numerical scoring of rival plans (NSRP) are usually based either on basis of dose-volume histograms (DVH) or the relative values of corresponding normal tissue complication probabilities (NTCP) and tumor control probabilities (TCP). An alternative method for NSRP based on biological integral dose (BID) is being proposed, which is illustrated using a case of pituitary tumor planned to receive a dose of 50 Gy in 25 fractions over 5 weeks. BID for the various alternate plans -2-field (2F), 3-field (3F), 220 degrees arc (ARC) and 3-field static multileaf collimator (MLC) were calculated using the integration of the product of extrapolated response dose and the corresponding mass of the tissue enclosed separately for tumor and the normal brain in the entire planned target volume or a selected range of dose (approximately 90% and above of the normalized dose). Ratios of the BID for the brain versus the tumor were obtained and the plans were ranked on the basis of the least value of this ratio. In all of these plans, although the DVHs for normal brain were different, the DVHs for tumor were almost identical. However, the BID values for brain for 2F, 3F, ARC, and MLC were 22.53 Joules (J), 21.176 J, 21.991 J, and 10.608 J, respectively, and for tumor 0.561 J, 0.552 J, 0.555 J, and 0.556 J, respectively. The corresponding brain/tumor values were 40.16 (2F), 38.36 (3F), 39.62 (ARC), and 19.08 (MLC), thus ranking the plans in order of merit as MLC, 3F, ARC, and 2F. The BID for volumes encompassed by 90% and more of the normalized dose magnified the differences between the plans, with 2F being 29.99, compared to 3.82 for MLC. Rankings of rival plans could be based on the concept of BID. It requires a lesser number of uncertain variables and therefore could be used as an alternative technique in evaluation of the different plans in routine clinical practice.