mkdir -p /home/daytona/workspace/radiology-exam && ls /home/daytona/workspace/

~/radiology-exam/generate_answers.py

from reportlab.lib.pagesizes import A4
from reportlab.lib.styles import getSampleStyleSheet, ParagraphStyle
from reportlab.lib.units import cm
from reportlab.lib import colors
from reportlab.platypus import (SimpleDocTemplate, Paragraph, Spacer,
                                 HRFlowable, PageBreak, Table, TableStyle)
from reportlab.lib.enums import TA_CENTER, TA_LEFT, TA_JUSTIFY

# ── document ──────────────────────────────────────────────────────────────────
OUTPUT = "/home/daytona/workspace/radiology-exam/Radiodiagnosis_Exam_Answers.pdf"

doc = SimpleDocTemplate(
    OUTPUT, pagesize=A4,
    leftMargin=2.5*cm, rightMargin=2.5*cm,
    topMargin=2*cm, bottomMargin=2*cm,
    title="Head & Neck / CNS Radiology – Model Answers",
    author="Orris Medical AI"
)

# ── styles ────────────────────────────────────────────────────────────────────
styles = getSampleStyleSheet()

INST_BLUE = colors.HexColor("#003366")
SECTION_GOLD = colors.HexColor("#8B6914")
BODY_DARK = colors.HexColor("#1A1A1A")

title_style = ParagraphStyle("Title2", parent=styles["Normal"],
    fontSize=15, textColor=INST_BLUE, spaceAfter=4,
    alignment=TA_CENTER, fontName="Helvetica-Bold")

subtitle_style = ParagraphStyle("Sub", parent=styles["Normal"],
    fontSize=11, textColor=INST_BLUE, spaceAfter=2,
    alignment=TA_CENTER, fontName="Helvetica-Bold")

info_style = ParagraphStyle("Info", parent=styles["Normal"],
    fontSize=9, textColor=colors.grey, alignment=TA_CENTER, spaceAfter=10)

section_style = ParagraphStyle("Section", parent=styles["Normal"],
    fontSize=12, textColor=SECTION_GOLD, spaceBefore=14, spaceAfter=4,
    fontName="Helvetica-Bold", borderPad=3)

q_style = ParagraphStyle("Q", parent=styles["Normal"],
    fontSize=11, textColor=INST_BLUE, spaceBefore=10, spaceAfter=4,
    fontName="Helvetica-Bold")

h2_style = ParagraphStyle("H2", parent=styles["Normal"],
    fontSize=10, textColor=INST_BLUE, spaceBefore=8, spaceAfter=3,
    fontName="Helvetica-Bold")

body_style = ParagraphStyle("Body", parent=styles["Normal"],
    fontSize=9.5, textColor=BODY_DARK, leading=15, spaceAfter=4,
    alignment=TA_JUSTIFY)

bullet_style = ParagraphStyle("Bullet", parent=styles["Normal"],
    fontSize=9.5, textColor=BODY_DARK, leading=14, leftIndent=18,
    spaceAfter=2, bulletIndent=6)

key_style = ParagraphStyle("Key", parent=styles["Normal"],
    fontSize=9.5, textColor=colors.HexColor("#5C0000"),
    fontName="Helvetica-Bold", spaceAfter=2, leftIndent=18)

def HR(): return HRFlowable(width="100%", thickness=0.5,
                             color=colors.HexColor("#AAAAAA"), spaceAfter=4)

def B(text): return f"<b>{text}</b>"
def I(text): return f"<i>{text}</i>"

def h(text):       return Paragraph(text, h2_style)
def p(text):       return Paragraph(text, body_style)
def bp(text):      return Paragraph(f"• {text}", bullet_style)
def kp(text):      return Paragraph(f"▶ {text}", key_style)
def sp(n=6):       return Spacer(1, n)

# ── content ───────────────────────────────────────────────────────────────────
story = []

# Title block
story += [
    Paragraph("ZYDUS MEDICAL COLLEGE AND HOSPITAL, DAHOD", title_style),
    Paragraph("DEPARTMENT OF RADIODIAGNOSIS", subtitle_style),
    Paragraph("Internal Examination — Theory Paper", subtitle_style),
    Paragraph("Subject: Head &amp; Neck Radiology and CNS Radiology", subtitle_style),
    Paragraph("Model Answers — Prepared by Orris Medical AI", info_style),
    HR(), sp(4),
    Paragraph("SECTION A — LONG ESSAY QUESTIONS (2 × 20 = 40 Marks)", section_style),
    HR(), sp(2),
]

# ══════════════════════════════════════════════════════════════════════════════
# Q1 — Carcinoma of Oral Tongue
# ══════════════════════════════════════════════════════════════════════════════
story += [
    Paragraph("Q1. Role of Imaging in Carcinoma of the Oral Tongue (20 Marks)", q_style),
    HR(),
    h("Introduction"),
    p("Carcinoma of the oral tongue (COT) is the most common oral cavity malignancy, accounting for ~40% of all oral cancers. The vast majority are squamous cell carcinomas (SCC). Men are predominantly affected, usually in the 6th–7th decades, with tobacco and alcohol as primary risk factors. Imaging is central to locoregional staging (T and N), surgical planning, and surveillance."),
    sp(4),

    h("1. Imaging Modalities"),
    p(B("a) Intraoral Ultrasonography (US)")),
    bp("High-frequency probe (≥15 MHz) placed directly in the oral cavity."),
    bp("Tumor appears as an irregular hypoechoic mass within the hyperechoic tongue musculature."),
    bp("Gold standard for measuring " + B("depth of invasion (DOI)") + " — the single most important prognostic factor (correlates with nodal metastasis risk)."),
    bp("DOI ≥4 mm warrants elective neck dissection; ≥10 mm upstages to T3 (8th edition AJCC)."),
    bp("Superior to MRI for superficial lesions and minimally displaced tumors."),
    bp("Can guide fine needle aspiration cytology (FNAC) of suspicious neck nodes."),
    sp(4),

    p(B("b) Magnetic Resonance Imaging (MRI)")),
    bp("Preferred cross-sectional modality for soft-tissue characterization of the primary tumor."),
    bp(B("T1W:") + " Tumor isointense to hypointense relative to muscle."),
    bp(B("T2W / STIR:") + " Tumor hyperintense; useful for mapping infiltration into floor of mouth, extrinsic tongue muscles (genioglossus, hyoglossus), mandible, and midline crossing."),
    bp(B("T1 post-Gd:") + " Avid enhancement; delineates depth, neurovascular invasion, perineural spread."),
    bp(B("DWI:") + " Restricted diffusion (low ADC ~0.9–1.1 × 10⁻³ mm²/s); helps differentiate SCC from reactive/inflammatory tissue."),
    bp("Dynamic contrast-enhanced (DCE) MRI: time-intensity curves assess tumour vascularity."),
    bp("Coronal and axial planes best for inferior extension toward floor of mouth."),
    sp(4),

    p(B("c) CT (with IV contrast)")),
    bp("Axial and coronal reformats with soft-tissue and bone windows."),
    bp("Primary tumor: hypodense relative to enhancing muscle; mild-to-moderate enhancement."),
    bp("Best for assessing " + B("cortical bone erosion") + " of mandible (buccal cortex first involved — lingual/alveolar invasion upstages to T4a)."),
    bp("Excellent for evaluating " + B("cervical nodal metastases") + " — size, necrosis, extranodal extension (ENE)."),
    bp("CT chest for distant metastases / second primary."),
    sp(4),

    p(B("d) PET-CT (18F-FDG)")),
    bp("Increasing role in advanced disease (T3/T4, N2/N3)."),
    bp("Superior to CT/MRI for detecting occult nodal disease and distant metastases."),
    bp("Post-treatment surveillance: detects residual/recurrent disease, with high negative predictive value ~95%."),
    sp(4),

    h("2. Key Imaging Findings"),

    p(B("Primary Tumor Staging (AJCC 8th Edition):")),

    # Table for T staging
    Table(
        [
            ["Stage", "Criteria"],
            ["T1", "DOI ≤5 mm, greatest dimension ≤2 cm"],
            ["T2", "DOI >5–10 mm, or greatest dimension >2–4 cm"],
            ["T3", "DOI >10 mm, or greatest dimension >4 cm"],
            ["T4a", "Invasion of mandible cortex, extrinsic tongue muscles, maxillary sinus, skin of face"],
            ["T4b", "Invasion of masticator space, pterygoid plates, skull base, or encasement of ICA"],
        ],
        colWidths=[2.5*cm, 12*cm],
        style=TableStyle([
            ("BACKGROUND", (0,0), (-1,0), INST_BLUE),
            ("TEXTCOLOR", (0,0), (-1,0), colors.white),
            ("FONTNAME", (0,0), (-1,0), "Helvetica-Bold"),
            ("FONTSIZE", (0,0), (-1,-1), 8.5),
            ("ROWBACKGROUNDS", (0,1), (-1,-1), [colors.HexColor("#EEF3FF"), colors.white]),
            ("GRID", (0,0), (-1,-1), 0.3, colors.grey),
            ("VALIGN", (0,0), (-1,-1), "MIDDLE"),
            ("LEFTPADDING", (0,0), (-1,-1), 5),
            ("RIGHTPADDING", (0,0), (-1,-1), 5),
            ("TOPPADDING", (0,0), (-1,-1), 3),
            ("BOTTOMPADDING", (0,0), (-1,-1), 3),
        ])
    ),
    sp(8),

    h("3. Levels of Cervical Lymph Node Involvement"),
    p("The oral tongue drains primarily to " + B("levels I–III") + " (especially levels IB and II). Contralateral or bilateral nodal spread occurs with midline crossing."),
    bp(B("Level IA") + " (submental): Tips of tongue, floor of mouth. Often first involved in anterior tongue lesions."),
    bp(B("Level IB") + " (submandibular): Main drainage for oral tongue; most commonly involved first echelon."),
    bp(B("Level II") + " (upper jugular): Second echelon. High-grade tumors skip to II directly."),
    bp(B("Level III") + " (mid-jugular): Involved with progressive nodal disease."),
    bp(B("Level IV/V") + ": Involved in advanced disease or skip metastases."),
    bp("Retropharyngeal nodes (Level VI): rare but documented."),
    p("Imaging criteria for malignant nodes: short axis >10 mm (>15 mm for level II), central necrosis, loss of fatty hilum, ENE (irregular capsule, infiltration of adjacent fat). ENE upstages to N3b regardless of number."),
    sp(4),

    h("Key Imaging Points (Summary)"),
    kp("Intraoral US is best for DOI measurement (most critical prognostic parameter)."),
    kp("MRI superior for soft-tissue extent, neurovascular invasion, and perineural spread."),
    kp("CT preferred for mandibular cortical involvement and nodal staging."),
    kp("PET-CT for occult distant metastases and post-treatment surveillance."),
    kp("Bilateral neck imaging mandatory — midline tumors have bilateral nodal spread."),
    sp(8),
    PageBreak(),
]

# ══════════════════════════════════════════════════════════════════════════════
# Q2 — MRI in Multiple Sclerosis
# ══════════════════════════════════════════════════════════════════════════════
story += [
    Paragraph("Q2. Role of MRI in Evaluation of Multiple Sclerosis; Differential Diagnosis of Multifocal White Matter Lesions (20 Marks)", q_style),
    HR(),
    h("Introduction"),
    p("Multiple sclerosis (MS) is the most common demyelinating disease of the CNS, affecting ~2.5 million people worldwide. It is an autoimmune T-cell mediated disorder causing focal demyelination and axonal loss. MRI is the cornerstone of diagnosis, monitoring, and treatment response assessment."),
    sp(4),

    h("1. MRI Sequences and Their Role"),
    bp(B("T2-weighted / FLAIR:") + " Most sensitive for MS plaques. Lesions appear hyperintense (bright). FLAIR suppresses CSF signal, making periventricular lesions more conspicuous."),
    bp(B("T1-weighted (non-contrast):") + " 'Black holes' — T1 hypointense lesions represent areas of permanent axonal loss and correlate with disability."),
    bp(B("T1 post-Gd:") + " Gadolinium-enhancing lesions = active inflammatory/demyelinating lesions (blood-brain barrier disruption). Detects activity 5–10× more than clinical relapse assessment."),
    bp(B("DWI:") + " Acutely demyelinating lesions may show restricted diffusion; helps distinguish from infarcts."),
    bp(B("MTR (Magnetisation Transfer Ratio):") + " Quantifies myelin loss; reduced in MS plaques."),
    bp(B("MR Spectroscopy:") + " Reduced NAA (neuronal loss), elevated Cho (membrane turnover), elevated Lac in acute lesions."),
    bp(B("Spinal Cord MRI (Sagittal STIR + T2 + post-Gd):") + " Short-segment (<2 vertebral levels) cord lesions, preferentially dorsal/lateral columns."),
    sp(4),

    h("2. Distribution of MS Lesions (McDonald 2017 Criteria Locations)"),
    bp(B("Periventricular:") + " Adjacent to lateral ventricles, particularly at calloso-septal interface. 'Dawson's fingers' — ovoid lesions oriented perpendicular to ventricles along medullary veins, best seen on sagittal FLAIR."),
    bp(B("Juxtacortical (cortical/subcortical):") + " At gray-white junction; U-fibers. Cortical lesions visible on DIR (double inversion recovery) sequences."),
    bp(B("Infratentorial:") + " Brainstem (outer margin of pons, floor of 4th ventricle), cerebellum, middle cerebellar peduncle."),
    bp(B("Spinal cord:") + " Cervical > thoracic; <2 vertebral segments; eccentric, posterior/lateral."),
    p(B("Dissemination in Space (DIS):") + " ≥1 T2 lesion in ≥2 of the 4 above locations. " + B("Dissemination in Time (DIT):") + " New T2 lesion on follow-up MRI or simultaneous Gd+ and Gd− lesions."),
    sp(4),

    h("3. Special MRI Signs in MS"),
    bp(B("Dawson's Fingers:") + " Periventricular ovoid lesions oriented along medullary veins, best on sagittal FLAIR."),
    bp(B("Central Vein Sign (CVS):") + " A thin vein running through the center of the lesion on susceptibility-weighted imaging (SWI); highly specific for MS (>97%). Differentiates MS from small vessel disease."),
    bp(B("Tumefactive MS:") + " Large (>2 cm) lesion with open ring enhancement (incomplete ring — open toward cortex), minimal mass effect, no surrounding vasogenic edema proportional to size."),
    bp(B("Brain Atrophy:") + " Whole-brain volume loss, particularly of gray matter; correlates with disability progression."),
    sp(4),

    h("4. Differential Diagnosis of Multifocal White Matter Lesions"),

    Table(
        [
            ["Condition", "Key Distinguishing Features on MRI"],
            ["Small vessel / ischemic\n(Fazekas grade I–III)", "Subcortical/periventricular; NO calloso-septal interface, NO spinal lesions; lacunar infarcts; risk factors (HTN, DM)"],
            ["ADEM", "Bilateral, asymmetric, large confluent WM lesions; gray matter involvement; monophasic; post-infectious/vaccination; no CVS"],
            ["Neuromyelitis Optica\n(NMOSD)", "Long-segment cord (≥3 segments); area postrema lesion; bilateral optic nerve; AQP4-IgG+; no Dawson's fingers"],
            ["CNS Vasculitis", "Multiple infarcts in multiple vascular territories; can involve cortex/leptomeninges; vessel wall enhancement on MR angiography"],
            ["Susac Syndrome", "Snowball lesions in corpus callosum body (NOT calloso-septal); branch retinal artery occlusions; hearing loss"],
            ["CADASIL", "Anterior temporal pole WM (pathognomonic); external capsule; family history; NOTCH3 mutation"],
            ["Lyme Neuroborreliosis", "Periventricular WM; cranial nerve enhancement; clinical history of tick exposure"],
            ["HIV Encephalopathy", "Bilateral symmetrical periventricular WM; no enhancement; diffuse atrophy"],
            ["Migraine", "Small subcortical/deep WM lesions; fronto-parietal; no infratentorial/calloso-septal; clinical correlation essential"],
            ["Brain Metastases", "Gray-white junction; ring enhancement; vasogenic edema disproportionate to lesion; known primary malignancy"],
        ],
        colWidths=[4.5*cm, 10.5*cm],
        style=TableStyle([
            ("BACKGROUND", (0,0), (-1,0), INST_BLUE),
            ("TEXTCOLOR", (0,0), (-1,0), colors.white),
            ("FONTNAME", (0,0), (-1,0), "Helvetica-Bold"),
            ("FONTSIZE", (0,0), (-1,-1), 8),
            ("ROWBACKGROUNDS", (0,1), (-1,-1), [colors.HexColor("#EEF3FF"), colors.white]),
            ("GRID", (0,0), (-1,-1), 0.3, colors.grey),
            ("VALIGN", (0,0), (-1,-1), "MIDDLE"),
            ("LEFTPADDING", (0,0), (-1,-1), 5),
            ("RIGHTPADDING", (0,0), (-1,-1), 5),
            ("TOPPADDING", (0,0), (-1,-1), 3),
            ("BOTTOMPADDING", (0,0), (-1,-1), 3),
        ])
    ),
    sp(8),

    h("5. MS Variants (MRI Features)"),
    bp(B("Marburg (Malignant) MS:") + " Multiple large T2 lesions; mass effect; perilesional edema; extensive enhancement. Rapidly progressive."),
    bp(B("Baló Concentric Sclerosis:") + " Concentric alternating rings of demyelination and preserved myelin — 'onion skin' or 'tree ring' appearance on T2/FLAIR. Pathognomonic."),
    bp(B("Schilder Disease:") + " Large (>2 cm) bilateral parieto-occipital ring-enhancing lesions. Responds to steroids."),
    sp(4),

    h("Key Points (Summary)"),
    kp("MRI detects MS lesions 5–10× more than clinical relapse evaluation."),
    kp("Dawson's fingers on sagittal FLAIR is the most characteristic pattern."),
    kp("Central Vein Sign on SWI is highly specific (>97%) for MS."),
    kp("McDonald 2017 criteria require DIS and DIT — both assessed by MRI."),
    kp("Spinal cord MRI mandatory — short-segment eccentric lesions confirm diagnosis."),
    sp(8),

    Paragraph("SECTION B — SHORT NOTES (6 × 10 = 60 Marks)", section_style),
    HR(), sp(2),
    PageBreak(),
]

# ══════════════════════════════════════════════════════════════════════════════
# Q3 — Pleomorphic Adenoma Parotid
# ══════════════════════════════════════════════════════════════════════════════
story += [
    Paragraph("Q3. Imaging Features of Pleomorphic Adenoma of the Parotid Gland (10 Marks)", q_style),
    HR(),
    h("Introduction"),
    p("Pleomorphic adenoma (PA) — also known as mixed parotid tumor — is the most common salivary gland tumor (~70–80% of all parotid neoplasms). It arises most commonly in the superficial lobe of the parotid gland. Histologically it contains epithelial, myoepithelial, and stromal (chondromyxoid) components. It is benign but carries a 5–10% risk of malignant transformation (carcinoma ex-pleomorphic adenoma) if left untreated."),
    sp(4),

    h("Ultrasound (First-Line)"),
    bp("Well-defined, " + B("oval or lobulated") + " hypoechoic mass with posterior acoustic enhancement."),
    bp("Homogeneous echogenicity in small tumors; heterogeneous in large tumors (due to myxoid/chondroid areas)."),
    bp("Smooth, clearly defined margins — pseudocapsule."),
    bp("On Doppler: internal vascularity present; peripheral and central flow."),
    bp("Cannot reliably differentiate PA from Warthin's tumor on US alone."),
    sp(4),

    h("CT Findings"),
    bp("Well-circumscribed, oval/lobulated mass in superficial or deep lobe of parotid."),
    bp("Homogeneous on non-contrast CT; " + B("heterogeneous after contrast") + " in larger tumors."),
    bp("Mild-to-moderate enhancement (less than Warthin's tumor)."),
    bp("No evidence of cortical bone destruction (unlike malignant tumors)."),
    bp("Deep lobe tumors cause medial displacement of the parapharyngeal fat — 'dumbbell' shape through stylomandibular tunnel."),
    sp(4),

    h("MRI Findings (Most Diagnostic)"),
    bp(B("T1W:") + " Hypointense to isointense relative to muscle."),
    bp(B("T2W:") + " " + B("Markedly hyperintense (bright white)") + " — cardinal feature. Due to high myxoid/chondroid stroma content and free water. T2 hyperintensity > Warthin's tumor."),
    bp(B("T1 post-Gd:") + " Slow, progressive, persistent enhancement — 'late washout' pattern on DCE. This distinguishes PA from malignant tumors which show rapid washout."),
    bp(B("DWI:") + " High ADC value (>1.5 × 10⁻³ mm²/s) — useful in differentiating from malignant tumors (low ADC) and Warthin's tumor (low ADC)."),
    bp(B("Capsule:") + " Hypointense fibrous capsule on all sequences. " + B("Capsular irregularity or satellite nodules") + " suggest malignant transformation."),
    sp(4),

    h("Key Differentiating Features from Other Parotid Tumors"),
    Table(
        [
            ["Feature", "Pleomorphic Adenoma", "Warthin's Tumor", "Malignant Tumor"],
            ["T2 signal", "Very bright (hyperintense)", "Intermediate", "Low-intermediate"],
            ["ADC value", "High (>1.5)", "Low (<1.0)", "Low (<1.0)"],
            ["Enhancement", "Progressive, late", "Early, rapid", "Rapid washout"],
            ["Margins", "Well-defined", "Well-defined", "Ill-defined, invasive"],
            ["Bilaterality", "Rare", "20% bilateral", "Rare"],
            ["Bone/nerve", "Absent", "Absent", "Present (VII palsy)"],
        ],
        colWidths=[3.5*cm, 4*cm, 3.5*cm, 4*cm],
        style=TableStyle([
            ("BACKGROUND", (0,0), (-1,0), INST_BLUE),
            ("TEXTCOLOR", (0,0), (-1,0), colors.white),
            ("FONTNAME", (0,0), (-1,0), "Helvetica-Bold"),
            ("FONTSIZE", (0,0), (-1,-1), 8),
            ("ROWBACKGROUNDS", (0,1), (-1,-1), [colors.HexColor("#EEF3FF"), colors.white]),
            ("GRID", (0,0), (-1,-1), 0.3, colors.grey),
            ("VALIGN", (0,0), (-1,-1), "MIDDLE"),
            ("LEFTPADDING", (0,0), (-1,-1), 4),
            ("TOPPADDING", (0,0), (-1,-1), 3),
            ("BOTTOMPADDING", (0,0), (-1,-1), 3),
        ])
    ),
    sp(6),
    kp("T2 hyperintensity + high ADC + progressive enhancement = hallmarks of pleomorphic adenoma on MRI."),
    kp("Satellite nodules or capsular breach → suspect malignant transformation (carcinoma ex-PA)."),
    sp(8),
]

# ══════════════════════════════════════════════════════════════════════════════
# Q4 — OMU and Paranasal Sinuses
# ══════════════════════════════════════════════════════════════════════════════
story += [
    Paragraph("Q4. Imaging Anatomy of the Osteomeatal Unit (OMU) and Paranasal Sinuses (10 Marks)", q_style),
    HR(),
    h("Introduction"),
    p("The osteomeatal unit (OMU) is a functional anatomical complex in the lateral nasal wall that represents the common drainage pathway for the anterior group of paranasal sinuses (frontal, anterior ethmoid, maxillary). CT of the paranasal sinuses — particularly coronal HRCT — is the gold standard for evaluating the OMU and planning functional endoscopic sinus surgery (FESS)."),
    sp(4),

    h("Components of the Osteomeatal Unit"),
    bp(B("Maxillary ostium:") + " Primary opening of the maxillary sinus into the ethmoid infundibulum. Located in the posterosuperior medial wall of the maxillary sinus."),
    bp(B("Ethmoid infundibulum:") + " A 3D cleft lateral to the uncinate process; receives drainage from maxillary sinus and anterior ethmoid cells."),
    bp(B("Uncinate process:") + " Thin, sickle-shaped projection of the ethmoid bone; key landmark. Medial wall of the infundibulum. Paradoxical curvature, pneumatization, and hypertrophy are common anatomical variants that cause OMU obstruction."),
    bp(B("Hiatus semilunaris:") + " Crescentic gap between the uncinate process and the bulla ethmoidalis through which the infundibulum opens into the middle meatus."),
    bp(B("Ethmoidal bulla:") + " Largest anterior ethmoid air cell; its lateral surface forms the medial wall of the orbit (lamina papyracea)."),
    bp(B("Middle meatus:") + " Space lateral to the middle turbinate; receives drainage from frontal, maxillary, and anterior ethmoid sinuses."),
    sp(4),

    h("Paranasal Sinuses — Anatomy and Imaging"),
    bp(B("Maxillary sinuses:") + " Largest sinuses. Pyramid-shaped, with apex toward zygomatic process. Floor is the hard palate. Drain via OMU into middle meatus. On CT: seen at level of nasal floor to orbit. Normally air-filled."),
    bp(B("Frontal sinuses:") + " Lie in the frontal bone above the orbits. Drain via frontonasal duct/recess → anterior ethmoid → middle meatus."),
    bp(B("Ethmoid sinuses:") + " Multiple small air cells between orbits. Anterior group drains to middle meatus (via OMU); posterior group drains to superior meatus."),
    bp(B("Sphenoid sinuses:") + " In the sphenoid bone; drain via sphenoethmoidal recess into superior meatus/nasopharynx (posterior group, independent of OMU)."),
    sp(4),

    h("HRCT Protocol for OMU"),
    bp("Coronal plane (primary) — best for OMU anatomy."),
    bp("Axial plane — frontal sinus drainage, sphenoid sinus."),
    bp("Bone algorithm reconstruction; slice thickness 1–2 mm."),
    bp("No IV contrast required for routine sinusitis evaluation."),
    sp(4),

    h("Anatomical Variants Predisposing to Sinusitis"),
    bp(B("Concha bullosa:") + " Pneumatization of the middle turbinate (most common anatomical variant — 20–40%); narrows middle meatus."),
    bp(B("Haller cell (infraorbital ethmoid cell):") + " Narrows maxillary sinus ostium."),
    bp(B("Onodi cell:") + " Posterior ethmoid cell that pneumatizes posteriorly toward optic canal — important surgical hazard."),
    bp(B("Deviated nasal septum (DNS):") + " Causes asymmetric pressure on OMU."),
    bp(B("Paradoxical middle turbinate curvature:") + " Curves laterally instead of medially."),
    sp(4),
    kp("HRCT paranasal sinuses in coronal plane is mandatory pre-FESS to map OMU anatomy."),
    kp("Opacification of the infundibulum is the earliest sign of OMU complex disease."),
    sp(8),
    PageBreak(),
]

# ══════════════════════════════════════════════════════════════════════════════
# Q5 — HRCT Temporal Bone / Cholesteatoma
# ══════════════════════════════════════════════════════════════════════════════
story += [
    Paragraph("Q5. Role of HRCT Temporal Bone in Cholesteatoma (10 Marks)", q_style),
    HR(),
    h("Definition"),
    p("Cholesteatoma is an accumulation of keratinizing squamous epithelium within the middle ear or mastoid, creating an expanding mass that causes progressive bone erosion. It may be congenital (2%) or acquired (primary — Shrapnell's membrane retraction; secondary — following perforation)."),
    sp(4),

    h("HRCT Technique"),
    bp("High-resolution CT (HRCT) of temporal bone: slice thickness 0.5–1 mm, bone algorithm, no IV contrast."),
    bp("Both axial and coronal planes mandatory."),
    bp("Protocol: helical acquisition with MPR in axial, coronal, and Pöschl/Stenvers planes."),
    bp("MDCT allows multiplanar reconstruction of ossicular chain, tegmen, facial nerve canal, and semicircular canals."),
    sp(4),

    h("HRCT Findings in Cholesteatoma"),
    p(B("Location (determines type):")),
    bp(B("Pars flaccida (Shrapnell's membrane) cholesteatoma:") + " Most common (~80%). Erosion of scutum (lateral epitympanic wall — the most sensitive sign). Soft-tissue mass in Prussak's space (superior recess of tympanic membrane)."),
    bp(B("Pars tensa cholesteatoma:") + " Less common; posterior superior retraction pocket."),
    bp(B("Congenital cholesteatoma:") + " Pearl-like mass anterior to malleus handle; intact TM."),
    sp(4),
    p(B("Key CT Findings:")),
    bp(B("Soft-tissue attenuation mass") + " (non-enhancing) in the middle ear cleft and/or mastoid antrum."),
    bp(B("Blunting/erosion of scutum") + " — earliest and most specific sign of pars flaccida cholesteatoma."),
    bp(B("Ossicular chain erosion:") + " Long process of incus (most commonly affected first), followed by malleus head and stapes suprastructure."),
    bp(B("Lateral semicircular canal (LSCC) fistula:") + " Erosion of bone over LSCC — important surgical finding (risk of perilymph fistula)."),
    bp(B("Tegmen tympani erosion:") + " Intracranial extension risk (meningitis, abscess)."),
    bp(B("Facial nerve canal erosion:") + " Tympanic segment most common; risk of iatrogenic VII nerve injury."),
    bp(B("Mastoid opacification") + " with confluent air cell destruction."),
    bp(B("Sinus plate erosion:") + " Sigmoid sinus thrombophlebitis risk."),
    sp(4),

    h("Limitations of HRCT"),
    bp("Cannot differentiate cholesteatoma from granulation tissue, cholesterol granuloma, or effusion on HRCT alone."),
    bp(B("MRI (non-echo-planar DWI or PROPELLER DWI)") + " is gold standard for this differentiation — cholesteatoma shows restricted diffusion (bright on DWI, dark on ADC)."),
    bp("MRI also detects recurrent/residual cholesteatoma post-surgery (avoids second-look surgery)."),
    sp(4),
    kp("Scutum erosion is the hallmark HRCT sign of acquired pars flaccida cholesteatoma."),
    kp("LSCC and tegmen erosion are critical surgical danger signs."),
    kp("DWI MRI (non-EPI) differentiates cholesteatoma from other middle ear masses."),
    sp(8),
]

# ══════════════════════════════════════════════════════════════════════════════
# Q6 — ACR TI-RADS
# ══════════════════════════════════════════════════════════════════════════════
story += [
    Paragraph("Q6. ACR TI-RADS Classification of Thyroid Nodules on Ultrasound (10 Marks)", q_style),
    HR(),
    h("Introduction"),
    p("The American College of Radiology Thyroid Imaging Reporting and Data System (ACR TI-RADS) was introduced in 2017 to standardize thyroid nodule reporting and guide management decisions — particularly whether to recommend FNA biopsy or surveillance."),
    sp(4),

    h("Five Ultrasound Categories — Point-Based Scoring"),
    p("Five sonographic features are evaluated. Points are assigned and summed to determine the TI-RADS category:"),

    Table(
        [
            ["Feature", "Category", "Points"],
            ["Composition", "Cystic/almost cystic", "0"],
            ["", "Spongiform", "0"],
            ["", "Mixed cystic/solid", "1"],
            ["", "Solid or almost solid", "2"],
            ["Echogenicity", "Anechoic", "0"],
            ["", "Hyperechoic / isoechoic", "1"],
            ["", "Hypoechoic", "2"],
            ["", "Very hypoechoic", "3"],
            ["Shape", "Wider-than-tall", "0"],
            ["", "Taller-than-wide", "3"],
            ["Margin", "Smooth / ill-defined", "0"],
            ["", "Lobulated / irregular", "2"],
            ["", "Extra-thyroidal extension", "3"],
            ["Echogenic foci", "None / large comet-tail", "0"],
            ["", "Macrocalcifications", "1"],
            ["", "Peripheral (rim) calcification", "2"],
            ["", "Punctate echogenic foci", "3"],
        ],
        colWidths=[4.5*cm, 7*cm, 3.5*cm],
        style=TableStyle([
            ("BACKGROUND", (0,0), (-1,0), INST_BLUE),
            ("TEXTCOLOR", (0,0), (-1,0), colors.white),
            ("FONTNAME", (0,0), (-1,0), "Helvetica-Bold"),
            ("FONTSIZE", (0,0), (-1,-1), 8),
            ("SPAN", (0,1), (0,3)), ("SPAN", (0,4), (0,7)),
            ("SPAN", (0,8), (0,9)), ("SPAN", (0,10), (0,12)),
            ("SPAN", (0,13), (0,17)),
            ("ROWBACKGROUNDS", (0,1), (-1,-1), [colors.HexColor("#EEF3FF"), colors.white]),
            ("GRID", (0,0), (-1,-1), 0.3, colors.grey),
            ("VALIGN", (0,0), (-1,-1), "MIDDLE"),
            ("LEFTPADDING", (0,0), (-1,-1), 5),
            ("TOPPADDING", (0,0), (-1,-1), 3),
            ("BOTTOMPADDING", (0,0), (-1,-1), 3),
        ])
    ),
    sp(8),

    h("TI-RADS Categories and Management"),
    Table(
        [
            ["Category", "Points", "Risk", "Management"],
            ["TR1 — Benign", "0", "<2%", "No FNA; no follow-up"],
            ["TR2 — Not suspicious", "2", "<2%", "No FNA; no follow-up"],
            ["TR3 — Mildly suspicious", "3", "~5%", "FNA if ≥2.5 cm; US follow-up if ≥1.5 cm"],
            ["TR4 — Moderately suspicious", "4–6", "~5–20%", "FNA if ≥1.5 cm; US follow-up if ≥1 cm"],
            ["TR5 — Highly suspicious", "≥7", ">20%", "FNA if ≥1 cm; US follow-up if ≥0.5 cm"],
        ],
        colWidths=[4.5*cm, 2*cm, 2.5*cm, 6*cm],
        style=TableStyle([
            ("BACKGROUND", (0,0), (-1,0), INST_BLUE),
            ("TEXTCOLOR", (0,0), (-1,0), colors.white),
            ("FONTNAME", (0,0), (-1,0), "Helvetica-Bold"),
            ("FONTSIZE", (0,0), (-1,-1), 8.5),
            ("ROWBACKGROUNDS", (0,1), (-1,-1), [colors.HexColor("#EEF3FF"), colors.white]),
            ("GRID", (0,0), (-1,-1), 0.3, colors.grey),
            ("VALIGN", (0,0), (-1,-1), "MIDDLE"),
            ("LEFTPADDING", (0,0), (-1,-1), 5),
            ("TOPPADDING", (0,0), (-1,-1), 3),
            ("BOTTOMPADDING", (0,0), (-1,-1), 3),
        ])
    ),
    sp(6),
    h("High-Risk Features (Warrant Lower Threshold for FNA)"),
    bp("Family history of medullary thyroid carcinoma or MEN2."),
    bp("Prior radiation to neck."),
    bp("Elevated serum calcitonin."),
    bp("Rapid growth on surveillance (>20% in 2 axes in <1 year)."),
    kp("TI-RADS uses a 5-feature point system; TR5 (≥7 points) requires FNA if ≥1 cm."),
    kp("Punctate echogenic foci (microcalcifications) and taller-than-wide shape are highest-risk features."),
    sp(8),
    PageBreak(),
]

# ══════════════════════════════════════════════════════════════════════════════
# Q7 — Imaging in Child with Proptosis
# ══════════════════════════════════════════════════════════════════════════════
story += [
    Paragraph("Q7. Imaging Approach to a Child with Proptosis (10 Marks)", q_style),
    HR(),
    h("Introduction"),
    p("Proptosis (exophthalmos) in a child is defined as protrusion of the eyeball beyond the orbital rim. It is a clinical emergency requiring systematic evaluation to distinguish benign from malignant, inflammatory from neoplastic, and unilateral from bilateral causes."),
    sp(4),

    h("Causes in Children — Age-Based Approach"),
    Table(
        [
            ["Age Group", "Common Causes"],
            ["Neonates", "Rhabdomyosarcoma, teratoma, dermoid/epidermoid, capillary hemangioma"],
            ["Infants/Toddlers", "Capillary hemangioma (most common benign orbital tumor in childhood), retinoblastoma, metastatic neuroblastoma, LCH"],
            ["Older children", "Rhabdomyosarcoma (most common primary malignant orbital tumor), lymphoma, orbital cellulitis, dermoid cyst, lymphangioma"],
        ],
        colWidths=[3.5*cm, 11.5*cm],
        style=TableStyle([
            ("BACKGROUND", (0,0), (-1,0), INST_BLUE),
            ("TEXTCOLOR", (0,0), (-1,0), colors.white),
            ("FONTNAME", (0,0), (-1,0), "Helvetica-Bold"),
            ("FONTSIZE", (0,0), (-1,-1), 8.5),
            ("ROWBACKGROUNDS", (0,1), (-1,-1), [colors.HexColor("#EEF3FF"), colors.white]),
            ("GRID", (0,0), (-1,-1), 0.3, colors.grey),
            ("VALIGN", (0,0), (-1,-1), "MIDDLE"),
            ("LEFTPADDING", (0,0), (-1,-1), 5),
            ("TOPPADDING", (0,0), (-1,-1), 3),
            ("BOTTOMPADDING", (0,0), (-1,-1), 3),
        ])
    ),
    sp(6),

    h("Imaging Protocol"),
    p(B("1. Ultrasound (First-Line)")),
    bp("High-frequency (7.5–15 MHz) B-mode + Doppler."),
    bp("Rapidly identifies cystic vs solid lesion, internal vascularity."),
    bp(B("Capillary hemangioma:") + " Well-defined, heterogeneous, hypervascullar mass; increases with crying/Valsalva."),
    bp(B("Lymphangioma:") + " Multiloculated cystic mass, fluid-fluid levels (hemorrhage), no flow on Doppler."),
    bp(B("Dermoid cyst:") + " Well-defined cystic lesion, usually at superotemporal orbit, no internal vascularity."),
    bp(B("Rhabdomyosarcoma:") + " Solid, heterogeneous, hypervascular, rapid growth."),
    sp(4),

    p(B("2. CT Scan (Bone Detail + Surgical Planning)")),
    bp("MDCT with MPR; axial and coronal planes."),
    bp("Best for: subperiosteal abscess (orbital cellulitis), bony destruction/remodeling, optic canal, and foreign body."),
    bp(B("Neuroblastoma metastases:") + " Permeative/lytic bone destruction of orbital walls; 'hair-on-end' periosteal reaction; bilateral 'raccoon eyes'."),
    bp(B("Langerhans Cell Histiocytosis:") + " Geographic lytic lesion with beveled edges in orbital roof."),
    bp(B("Dermoid:") + " Bone scalloping at superotemporal orbital wall."),
    sp(4),

    p(B("3. MRI (Gold Standard for Soft-Tissue Lesions)")),
    bp("T1, T2, STIR, T1 fat-sat post-Gd; axial and coronal planes."),
    bp(B("Rhabdomyosarcoma:") + " T1 iso, T2 hyperintense solid mass with avid enhancement; involvement of orbital apex or intracranial extension."),
    bp(B("Capillary hemangioma:") + " T1 iso, T2 markedly hyperintense with 'multiple flow voids'; avid enhancement."),
    bp(B("Retinoblastoma:") + " T2 hypointense (due to calcification); avid enhancement; may show optic nerve involvement or choroidal invasion."),
    bp(B("Optic nerve glioma:") + " Fusiform enlargement of optic nerve; T2 bright; associated with NF1."),
    bp(B("Orbital cellulitis / subperiosteal abscess:") + " Rim-enhancing collection displacing orbital fat."),
    sp(4),
    kp("MRI is preferred in children to avoid radiation — use only when MRI cannot characterize."),
    kp("Raccoon eyes + bone destruction = metastatic neuroblastoma until proven otherwise."),
    kp("Rhabdomyosarcoma: most common malignant orbital tumor in childhood; urgent evaluation."),
    sp(8),
]

# ══════════════════════════════════════════════════════════════════════════════
# Q8 — Carcinoma Larynx CT/MRI
# ══════════════════════════════════════════════════════════════════════════════
story += [
    Paragraph("Q8. CT/MRI Features of Carcinoma Larynx and Laryngeal Compartments (10 Marks)", q_style),
    HR(),
    h("Laryngeal Compartments"),
    p("The larynx is divided into three compartments that determine patterns of spread and treatment:"),
    bp(B("Supraglottic:") + " Epiglottis, aryepiglottic folds, arytenoids, false vocal cords, laryngeal ventricles. Above the lateral margin of the ventricle."),
    bp(B("Glottic:") + " True vocal cords, anterior commissure, posterior commissure. 5 mm above/below free edge of cord."),
    bp(B("Subglottic:") + " From inferior glottic boundary to inferior border of cricoid cartilage."),
    sp(4),

    h("CT Imaging Protocol"),
    bp("MDCT with IV contrast; 1.5–3 mm slices; axial + coronal + sagittal MPR."),
    bp("Scan during quiet breathing (not Valsalva) to keep cords in neutral position."),
    bp("Include neck (base of skull to carina) for nodal assessment."),
    sp(4),

    h("CT Features of Laryngeal Carcinoma"),
    bp(B("Soft tissue:") + " Asymmetric, enhancing soft-tissue mass arising from any compartment. Glottic SCC most common (~60–65%)."),
    bp(B("Cartilage invasion:") + " " + B("Most important prognostic indicator (T4a)") + ". CT findings: sclerosis of cartilage (early, non-specific), erosion, lysis, or frank destruction. Inner cortex erosion is most reliable sign."),
    bp(B("Pre-epiglottic space (PES) invasion:") + " Fat stranding/obliteration in the hypodense pre-epiglottic fat; seen on sagittal/axial CT."),
    bp(B("Paraglottic space invasion:") + " Fat in the paraglottic space replaced by tumor; crosses compartments."),
    bp(B("Anterior commissure involvement:") + " Critical; extends to contralateral cord, increases local failure risk."),
    bp(B("Subglottic extension:") + " Subglottic soft tissue >5 mm (anterior) or >10 mm (posterior) is T3."),
    sp(4),

    h("MRI Features"),
    bp(B("T1W:") + " Tumor isointense to muscle."),
    bp(B("T2W:") + " Moderately hyperintense; best for PES and paraglottic space invasion."),
    bp(B("T1 post-Gd:") + " Enhancement; best for perineural spread and cartilage marrow replacement."),
    bp(B("Cartilage invasion on MRI:") + " T1 low signal replacing normal T1-bright fatty marrow; T2 high signal in cartilage."),
    bp("MRI superior to CT for cartilage marrow invasion and soft-tissue extent; CT better for cartilage cortical erosion and calcification."),
    sp(4),

    h("T-Staging (AJCC 8th)"),
    Table(
        [
            ["Stage", "Description"],
            ["T1", "Glottis: limited to vocal cords, normal mobility; Supraglottis: limited to 1 subsite"],
            ["T2", "Glottis: supra/subglottic extension, normal/impaired mobility; Supraglottis: mucosa of >1 subsite"],
            ["T3", "Cord fixation; PES/paraglottic space involvement; inner cortex erosion of thyroid cartilage"],
            ["T4a", "Thyroid cartilage outer cortex or trachea, deep tongue, strap muscles, thyroid, esophagus"],
            ["T4b", "Prevertebral space, mediastinal structures, ICA encasement"],
        ],
        colWidths=[2.5*cm, 12.5*cm],
        style=TableStyle([
            ("BACKGROUND", (0,0), (-1,0), INST_BLUE),
            ("TEXTCOLOR", (0,0), (-1,0), colors.white),
            ("FONTNAME", (0,0), (-1,0), "Helvetica-Bold"),
            ("FONTSIZE", (0,0), (-1,-1), 8.5),
            ("ROWBACKGROUNDS", (0,1), (-1,-1), [colors.HexColor("#EEF3FF"), colors.white]),
            ("GRID", (0,0), (-1,-1), 0.3, colors.grey),
            ("VALIGN", (0,0), (-1,-1), "MIDDLE"),
            ("LEFTPADDING", (0,0), (-1,-1), 5),
            ("TOPPADDING", (0,0), (-1,-1), 3),
            ("BOTTOMPADDING", (0,0), (-1,-1), 3),
        ])
    ),
    sp(6),
    kp("Cartilage invasion = T4a; indicates surgery over organ-preservation protocol."),
    kp("PES and paraglottic space fat obliteration are critical findings on CT/MRI."),
    kp("MRI superior for marrow invasion; CT superior for cortical erosion."),
    sp(8),
    PageBreak(),
]

# ══════════════════════════════════════════════════════════════════════════════
# Q9 — Medulloblastoma CT/MRI
# ══════════════════════════════════════════════════════════════════════════════
story += [
    Paragraph("Q9. Imaging Features of Medulloblastoma on CT and MRI (10 Marks)", q_style),
    HR(),
    h("Introduction"),
    p("Medulloblastoma is the most common malignant brain tumor of childhood (~20% of pediatric CNS tumors) and the most common pediatric posterior fossa tumor. It is a WHO Grade 4 embryonal tumor, arising from pluripotent cells of the cerebellar vermis. Peak age: 3–8 years; second peak in adolescents/young adults (lateral hemisphere variant). Male predominance (M:F = 2:1)."),
    sp(4),

    h("CT Findings"),
    bp(B("Location:") + " Midline cerebellar vermis in children; lateral cerebellar hemisphere in older adolescents/adults (desmoplastic variant)."),
    bp(B("Density:") + " " + B("Hyperdense") + " on NCCT (due to high nuclear-to-cytoplasmic ratio, dense cellularity). This is the classic hallmark."),
    bp(B("Calcification:") + " Present in ~15–20% of cases; punctate or nodular."),
    bp(B("Cystic change:") + " In ~15–40%; heterogeneous areas."),
    bp(B("Enhancement:") + " Avid, heterogeneous enhancement post-contrast; may be irregular."),
    bp(B("4th ventricle compression:") + " Tumor grows from vermis to fill/compress the 4th ventricle → obstructive hydrocephalus (almost always present at diagnosis)."),
    bp(B("Leptomeningeal spread:") + " 'Drop metastases' — nodular enhancement along spinal cord surface (check spinal CT/MRI)."),
    sp(4),

    h("MRI Findings (Definitive Characterization)"),
    bp(B("T1W:") + " Hypointense to isointense relative to gray matter."),
    bp(B("T2W:") + " Variable — may be iso to mildly hyperintense; heterogeneous with cystic/necrotic foci."),
    bp(B("FLAIR:") + " Hyperintense; perilesional edema. Surrounding vasogenic edema typically mild."),
    bp(B("DWI:") + " " + B("Restricted diffusion (bright on DWI, dark on ADC)") + " — ADC typically <0.6–0.8 × 10⁻³ mm²/s. Reflects dense cellularity. Highly characteristic and differentiates from ependymoma (higher ADC) and ATRT."),
    bp(B("T1 post-Gd:") + " Avid, heterogeneous enhancement. Leptomeningeal ('sugar-coating') enhancement indicates CSF dissemination."),
    bp(B("MR Spectroscopy:") + " High Cho/NAA ratio, elevated Tau (taurine) peak — relatively specific for medulloblastoma."),
    bp(B("Perfusion MRI (rCBV):") + " Elevated relative CBV reflecting high vascularity."),
    sp(4),

    h("Staging — Chang Classification (Modified)"),
    bp(B("M0:") + " No metastases."),
    bp(B("M1:") + " Microscopic tumor cells in CSF."),
    bp(B("M2:") + " Gross seeding in cerebellum/cerebrum/3rd–4th ventricle."),
    bp(B("M3:") + " Gross seeding in spinal subarachnoid space."),
    bp(B("M4:") + " Metastases outside CNS."),
    p("Mandatory staging MRI: post-contrast brain MRI + " + B("whole-spine MRI") + " (ideally preoperative, or within 2–4 weeks post-op before reactive enhancement confounds). Spine MRI shows drop metastases as linear/nodular enhancement along cord."),
    sp(4),

    h("Differential Diagnosis of Posterior Fossa Mass in Children"),
    Table(
        [
            ["Tumor", "Key Differentiating Feature"],
            ["Medulloblastoma", "Hyperdense NCCT; restricted DWI; midline; <10 yr"],
            ["Ependymoma", "Arises from floor of 4th ventricle; 'plastic' through foramina; calcification common; less restricted DWI"],
            ["Pilocytic astrocytoma", "Cystic + mural nodule; T2 very bright; enhancing mural nodule; NO restricted DWI"],
            ["ATRT", "<3 yr; DWI restriction but less intense; associated with SMARCB1/INI1 deletion"],
            ["Brainstem glioma (DIPG)", "Diffuse intrinsic expansion of pons; T2 bright; no/minimal enhancement; Histone H3 K27M"],
        ],
        colWidths=[4.5*cm, 10.5*cm],
        style=TableStyle([
            ("BACKGROUND", (0,0), (-1,0), INST_BLUE),
            ("TEXTCOLOR", (0,0), (-1,0), colors.white),
            ("FONTNAME", (0,0), (-1,0), "Helvetica-Bold"),
            ("FONTSIZE", (0,0), (-1,-1), 8.5),
            ("ROWBACKGROUNDS", (0,1), (-1,-1), [colors.HexColor("#EEF3FF"), colors.white]),
            ("GRID", (0,0), (-1,-1), 0.3, colors.grey),
            ("VALIGN", (0,0), (-1,-1), "MIDDLE"),
            ("LEFTPADDING", (0,0), (-1,-1), 5),
            ("TOPPADDING", (0,0), (-1,-1), 3),
            ("BOTTOMPADDING", (0,0), (-1,-1), 3),
        ])
    ),
    sp(6),
    kp("Hyperdense on NCCT + restricted DWI + midline posterior fossa = medulloblastoma."),
    kp("Mandatory whole-spine MRI for leptomeningeal staging (preoperative preferred)."),
    kp("Taurine peak on MRS is relatively specific for medulloblastoma."),
    sp(8),
]

# ══════════════════════════════════════════════════════════════════════════════
# Q10 — NCCT / CT Angiography Acute Ischemic Stroke
# ══════════════════════════════════════════════════════════════════════════════
story += [
    Paragraph("Q10. Role of NCCT and CT Angiography in Acute Ischemic Stroke (10 Marks)", q_style),
    HR(),
    h("Introduction"),
    p("Acute ischemic stroke (AIS) is a medical emergency. The imaging algorithm must be completed within minutes as 'time is brain' (~1.9 million neurons die per minute). Non-contrast CT (NCCT) is the universal first-line study; CT angiography (CTA) is performed concurrently to identify large vessel occlusion (LVO) — the target for mechanical thrombectomy."),
    sp(4),

    h("1. Non-Contrast CT (NCCT)"),
    p(B("Primary role: Exclude hemorrhage.")),
    p("NCCT cannot reliably identify early ischemia (<6 hours) but has specific early signs:"),
    sp(4),

    p(B("Early CT Signs of Ischemia (within 0–6 hours):")),
    bp(B("Hyperdense Middle Cerebral Artery (HMCA) Sign:") + " Focal hyperdensity in the MCA trunk or branch = intraluminal thrombus. Present in ~30–50% of acute MCA occlusions. Highly specific (~90%) for LVO."),
    bp(B("'Dot sign':") + " Hyperdense dot in sylvian fissure branches of MCA = distal thrombus."),
    bp(B("Sulcal effacement:") + " Loss of normal cortical sulci due to cytotoxic edema in the territory."),
    bp(B("Loss of gray-white differentiation:") + " Lenticulostriate territory: loss of insular ribbon (insular ribbon sign), blurring of basal ganglia/caudate."),
    bp(B("Insular ribbon sign:") + " Loss of insular cortex gray-white interface — early sign of MCA territory infarct."),
    bp(B("ASPECTS (Alberta Stroke Program Early CT Score):") + " 10-point score for MCA territory ischemia. Regions: caudate, lentiform nucleus, internal capsule (IC), insular ribbon (I), M1–M6 (cortical regions). Score ≤6 predicts poor outcomes; score ≥7 favors intervention."),
    sp(4),

    p(B("Role of NCCT in Thrombolysis Decision:")),
    bp("Exclude intracranial hemorrhage (absolute contraindication to tPA)."),
    bp("Identify established large territory infarct (>1/3 MCA territory) — relative contraindication."),
    bp("ASPECTS ≥6 supports IV tPA eligibility within 4.5 hours."),
    sp(4),

    h("2. CT Angiography (CTA)"),
    p(B("Performed immediately after NCCT (within the same session).")),
    bp(B("Coverage:") + " Aortic arch to vertex (whole-head CTA) — evaluates entire cervicocranial vasculature."),
    bp(B("Identifies LVO:") + " Site, extent of occlusion (ICA terminus, MCA-M1/M2, basilar artery, PCA)."),
    bp(B("Thrombus length:") + " CTA can measure thrombus length. >8 mm thrombus = poor recanalization with tPA alone → favors thrombectomy."),
    bp(B("Collateral status:") + " Pial collateral grading on CTA (Tan score, rLMC score) predicts penumbra viability and outcome with thrombectomy."),
    bp(B("Tandem occlusion:") + " Cervical ICA stenosis/occlusion + ipsilateral intracranial LVO — impacts intervention strategy."),
    bp(B("CT Angiography Source Images (CTA-SI):") + " Regions of low density = poor perfusion / infarct core. Correlates with DWI on MRI."),
    sp(4),

    p(B("CT Perfusion (CTP) — Complementary:")),
    bp(B("CBF:") + " Cerebral blood flow map — low in infarct core and penumbra."),
    bp(B("CBV:") + " Cerebral blood volume — low in infarct core (dead tissue); maintained in penumbra."),
    bp(B("Tmax:") + " Time to maximum of residue function — best marker of penumbra (>6 sec threshold)."),
    bp(B("MTT:") + " Mean transit time — prolonged in both core and penumbra."),
    bp("Target mismatch (penumbra > core): guides extended-window thrombectomy (6–24 hr — DAWN and DEFUSE-3 criteria)."),
    sp(4),

    h("Imaging Paradigm in Acute Stroke (Time-Based)"),
    Table(
        [
            ["Time Window", "Imaging", "Treatment"],
            ["0–4.5 hr", "NCCT + CTA", "IV tPA if eligible; Thrombectomy for LVO"],
            ["0–6 hr", "NCCT + CTA + CTP (if needed)", "Thrombectomy for LVO (DAWN/DEFUSE)"],
            ["6–24 hr", "NCCT + CTA + CTP (mandatory mismatch)", "Thrombectomy if mismatch criteria met"],
            [">24 hr", "MRI/CT perfusion", "No reperfusion; supportive care"],
        ],
        colWidths=[3*cm, 5.5*cm, 6.5*cm],
        style=TableStyle([
            ("BACKGROUND", (0,0), (-1,0), INST_BLUE),
            ("TEXTCOLOR", (0,0), (-1,0), colors.white),
            ("FONTNAME", (0,0), (-1,0), "Helvetica-Bold"),
            ("FONTSIZE", (0,0), (-1,-1), 8.5),
            ("ROWBACKGROUNDS", (0,1), (-1,-1), [colors.HexColor("#EEF3FF"), colors.white]),
            ("GRID", (0,0), (-1,-1), 0.3, colors.grey),
            ("VALIGN", (0,0), (-1,-1), "MIDDLE"),
            ("LEFTPADDING", (0,0), (-1,-1), 5),
            ("TOPPADDING", (0,0), (-1,-1), 3),
            ("BOTTOMPADDING", (0,0), (-1,-1), 3),
        ])
    ),
    sp(6),
    kp("NCCT: rule out hemorrhage, identify HMCA sign and ASPECTS score."),
    kp("CTA: identify LVO site and collateral status — determines thrombectomy eligibility."),
    kp("ASPECTS ≤6 predicts poor outcomes; ≥7 favors intervention."),
    kp("Hyperdense MCA sign is the most important early CT sign of LVO."),
    sp(10),

    HR(),
    Paragraph("END OF MODEL ANSWERS", ParagraphStyle("End", parent=styles["Normal"],
        fontSize=10, textColor=INST_BLUE, alignment=TA_CENTER,
        fontName="Helvetica-Bold", spaceBefore=6, spaceAfter=4)),
    Paragraph(
        "Zydus Medical College and Hospital, Dahod — Department of Radiodiagnosis | "
        "Prepared by Orris Medical AI | May 2026",
        ParagraphStyle("Footer", parent=styles["Normal"],
            fontSize=8, textColor=colors.grey, alignment=TA_CENTER)),
]

# ── build ─────────────────────────────────────────────────────────────────────
doc.build(story)
print(f"PDF generated: {OUTPUT}")

cd /home/daytona/workspace/radiology-exam && python generate_answers.py 2>&1

ls -lh /home/daytona/workspace/radiology-exam/Radiodiagnosis_Exam_Answers.pdf